High End EM Locators: RD8000, RD8100 and vLocPro2

0:56Oh, morning guys. I didn't realize you just jumped in the room. Sorry. I was a little bit distracted there.

1:01Well, we're just waiting for everyone to get in, guys, and um we'll make a start. I'm going to turn my video off for a second, just while I do a few bits.

2:20Morning guys, welcome to the room. Just waiting for everyone to get in. Don't worry if you can't see anything just yet.

2:35Francisco, where are you? 5:28 AM here. Good morning, and thank you for making the effort.

3:11How's everything in Paraguay, Francisco? Good of you to join us this morning.

3:30Morning Shane. Morning Jason. Where are you, Jason? 7:29 PM. Oh, yeah. I'm guessing Oz.

3:50Morning guys. You can see us now. Yeah, I'm I'm on as well.

4:01Can you see us guys? Give us a shout. Hello. Morning Martin, Bill. Tito. I'm going to say, this is going to get tedious, isn't it?

4:23There is a a poll there, guys, if you could answer that poll. That'd be fantastic, please. Just give us an idea of uh the audience that we've got today.

4:39And I think everyone's in the room who's coming. So, so welcome. I recognize some of the names, guys, so I think some of you have joined us before.

5:01Everyone else got sound, guys? You can hear us okay? Not sure what the problem is there, but can everyone else hear us? I'm assuming so.

5:28Okay, so, so welcome, guys, for our um online session this morning. This session is um high-end RD locators.

5:37So, we're going to talk about um RD8000, 8100s, PLT Pros, um all all the high-end stuff. We've got some um good information to share with you guys, we hope, anyway. Um I'm I'm at Sygma HQ in in Wigan,

5:51um here all on my own, and and Steve's at home down south somewhere. Bristol. Bristol.

6:01So, quick intro, guys. Um my name's Pete Ashcroft. Um Sygma, we're we're a specialist training provider in utility location. I'm sure most of you here are are aware of us, guys.

6:12Um we do um uh the five-day course at the survey school, the utility mapping survey course. We do like one-day courses, just on RD8000, CAT and Genny, but we're all geared around utility location.

6:24Uh my personal background, very quickly, I I guess most of you have heard this by now. Um I started with Radiodetection when I was um about 20 years old. Um interestingly, guys, Steve Mellor, who's with us,

6:37uh was my boss. He gave me the job all them years ago, so he was um and we're still working together all this time later.

6:47Um so, you've um you've got a good um a good um experience here, guys, I guess today. Uh lots of experience from both both both Steve and I. Uh Steve's going to be doing most of the session, I'll be jumping in with a few bits I've got for you as well,

7:02um guys. So, um I'll let Steve introduce himself shortly. A little bit on the software, guys. We want to keep these sessions interactive, so ask questions. We will be asking you questions. If you're not sure of something, chuck it in the chat box, and and we'll expand on it.

7:19Um um there's a bit of a delay on the software, guys. It's about 7 to 10 seconds, so what you're hearing through your speakers now, I said 10 seconds ago. Um so, it makes it a little bit tricky...

7:39Pete: So, I'll hand you over to Steve now. He'll give you a quick intro, and then we'll crack on.

8:03Steve: Morning, folks. Thanks for attending. Very, very brief background for those of you guys who don't know me. I started in this business 40-something-odd years ago. My dad bought a franchise for the North of England through a company called Electrolocation. Electrolocation was a small Bristol-based company manufacturing some fairly Heath Robinson-type kit and selling off franchises. So, my dad bought a North of England franchise, and I was bored with school, so I started working with him as a teenager back in the 1970s.

8:24Steve: Electrolocation became Radiodetection, and they stopped running the franchises and started manufacturing, producing equipment, and selling it. So, we then went on to do a combination of surveying. I mean, initially, my job was surveyor's assistant and then surveyor. And then we started actually promoting the products around the North of England, and then eventually, I moved to the States, worked for the company.

8:50Steve: Moved back to the UK in the late '80s, and did a whole variety of jobs within Radiodetection: power products, pipelines, product development, training. Sad admission, I know, but this is all I've ever done, and I'm getting too old to do anything else anyway. So, 40-something-odd years of using locators.

9:15Steve: I keep saying I'll get a proper job one day, but I'm getting a bit old for that now, so this is it, guys. As Pete said, chuck your thoughts, messages, comments in as we're going through, and we'll get started. Pete will be jumping in and out, and then he's got to shoot off somewhere, so if I can get this thing working...

9:50Pete: I've been monitoring the chat, guys, so any questions, throw it in there. I'll keep an eye on the chat, and I'll and I'll put them to Steve. There is a few in today, guys. So, if you look at the chat box, when you do type a comment in, you can mark it as a question, and that just makes it easier for me to see when you're when you're using the chat box.

10:11Steve: So, hopefully, I've gone into a tiny little thumbnail-type image, which is probably a lot more easy on your eyes. As Pete said, we're covering the 8000, 8100, vLocPro3. You guys might be using other kit out there. Whatever kit you're using, it's going to be very, very similar to this, so... And my laptop is going very, very slowly at the moment.

10:39Steve: So, we're going to cover aspects of things like how to apply signals, the best way of doing it, frequencies, aerials, CD, that kind of stuff. And as Pete said, if there's anything as we're going through you guys want to add in, you know, thoughts, comments... You're saying you're having playback problems, Stefan. I don't know about... Well, Jeff's saying about being hard to log in today. I don't know if that's just web traffic or... I'm no expert on...

11:15Pete: We've had a few issues this week with the login system. I'm still playing around with it with the notifications and and and login and stuff. I'll I'll sort that, don't worry. You carry on.

11:24Steve: What we what we have to assume on these courses, guys, is that you've used the kit quite comprehensively. You've probably had training before. So, we have to make some assumptions. Obviously, once we start doing this as a proper online platform replacing some of the traditional methods of training, we'll have a much better feel for everybody's experience, but...

11:50Steve: So, with any of this kit, and you'll notice quite predominantly there's some RD transmitters, but as I said to you a minute ago, a transmitter is pretty much the same as any other transmitter. Frequencies, power outputs, and things like that may vary, but the methodology is exactly the same. So...

12:06Steve: With a Tx-10 or a vLoc transmitter, whichever you guys are using, you've got generally four different ways of doing it. I suppose technically there's five, but for most people, you're probably familiar with the first or number one, two, and four. So, number one is direct connection, obviously just taking your red and black leads, connecting it to whatever you're trying to locate. Number two is signal clamp, which is very useful, common way of tracing things.

12:35Steve: Number three, you guys might not have come across it. Some of you guys might have done. Plug connector is useful in places like military sites, big industrial sites. Most of us aren't particular, aren't particularly overly happy with the plug connector because of some of its issues, but it can be useful at times.

12:50Steve: It just allows you to plug the transmitter into a plug socket in a building, switch both the transmitter and the plug socket on, and that will put a signal into the live LV supply. There are some issues with using those things, but they can be useful. And then induction is induction. Every transmitter is capable of producing an induction signal. If we get time, we'll cover some stuff on induction and nulling out. We'll see how we get on.

13:11Steve: So, I'm guessing you guys are familiar with how to use connection. Connection, your red lead to what you're trying to find, black lead to an earth. It's always considered best practice, even though the transmitter produces an AC signal. The reason being is we're going to cover CD later, and that is very important that you do get those leads in that orientation.

13:50Steve: Probably one of the biggest issues when you're out there is trying to get an earth, and this tried-and-tested technique has been around for years. It's never been very well documented. We've started doing some booklets which go along with the training course, which show you these little tips and tricks. But water's been, or any kind of fluid has been, a technique for getting earth. So, where you can't get the earth pin in the ground, in this scenario here, we've clipped onto a steel gas riser, and we're getting an earth. Just any old water will do, or Coke, or tea, coffee. Just lay down next to the brickwork so the water soaks away. The obvious thing to say, on a wet, sorry, on a hot summer's day, you're going to need quite a lot of water. On a wet day like it is in Bristol today, just find a puddle. That'll do.

21:30...transmitters like we used to. Um, yeah, exactly, guys. And also, guys, going back to pipes, think about high-pressure gas pipes. If you want to trace a high-pressure gas pipe, you can trace them for great distances. Again, it's insulated. It's traveling down it further, yeah. Okay, because it's an insulated... So, when we talk about earth position, though, it does have a more of an effect, I would say, on on on pipes. So, if we're if we look at again at that gas pipe scenario here,

21:58just give me a sec, guys. So, this is our pipe. If on the gas pipe we clip on and earth it close, we're actually encouraging more of our signal to jump off early, if you like. So, we don't trace as far. If we extend the earth out like this, you know, further away, we've we've potentially get more signal running down the pipe. Now, a lot of you said 90 degrees, but just think about this. When the earth's at 90 degrees like this, half my signal will run that way and half will run that way.

22:28You're effectively wasting half your signal because it's going in the wrong direction. So, instead, think about putting the earth at an angle like this, 45, we'd now get maybe 70 going that way. So, can you see we can angle the signal depending on the angle of the earth, basically, we can direct it. Also, think about other things as well. Which way do you want to trace? If I've got a house up here with a pipe going to it, if I put the earth down here,

22:52it doesn't really want to take that turn. It wants to carry on down the main. But if I put the earth up this way, it now wants to take that turn, but I probably won't get as much going down the main. Okay? So, all these factors are things you need to consider when you're putting that earth position in, guys. Does does that make sense to everyone, guys? Do you accept that? You you okay with that? So, we normally go into this on a obviously a lot more detail on on on the courses that we do. Now, the other thing to consider, though, guys, and we're going to talk about this later, the downside of doing this, and we've got a classic example of this

23:19outside our office here. If if we have a metal water pipe like this, and we hook the Genny onto it and earth it down here, what happens outside here is we've got a parallel utility. So, the signal now goes down here, and it returns along here, yeah. Now, in reality, this should have a stronger signal on it because it's the one we're hooked up to. However, in the real world, this is a meter deep,

23:49this is 300 mil deep. So, what we end up tracing is the wrong service. But if we get the earth and earth it close, as Steve said, to the rim of the box here, we now get a completely different result. We've minimized the signal coming back down here, and we locate this one. So, so there's there's pros and cons to it, yeah. If I extend it, I might get more signal, but I'm running the risk of it coming back down other utilities. The I guess the important message with the earth is understanding what it does and and playing around with it, guys.

24:19Okay? Is everyone okay with that, guys, yeah? Makes sense? Any questions on that? And if not, I will hand you back over to Steve. That section was from the Genny bit that we normally do, guys, but I just I just thought I'd throw a little bit in there. So,

24:47The other thing you may find is, like I said earlier on about earthing, you're struggling to get your earth pin in, maybe got no water. Another metal structure, drainage, anything in the ground that's not related to other services that are detectable, basically. So, I wouldn't use a comms lid or electric lid, but you can certainly use drainage lids

25:14or an old road sign, anything that's um in the ground that's going to give you an earth, gully, something like that. And as Pete was just saying about forcing signal in certain directions, if you know or you've got an idea of where you want to trace, although we were saying keep your earth close, and a lot of you guys made some good comments there about um it does vary, and that's very true. But if you want to make your earth, sorry, make your signal go in a certain direction, move your earth in that direction.

25:46Obviously, you'd need to move your cable away because your your earth lead cable is going to give you a big signal, or just accept the fact that in that area, you're not going to get a very clear signal. I have used fences for earth. I don't recommend it. If it's a short bit of fence, uh it may well be okay. If it's a long bit of fence, you got to bear in mind these are always double-headed.

26:15So, by clipping onto a fence, you're also generating a huge amount of signal, and that fence becomes a very big induction antenna. So, that could also cause other issues. And on the right-hand side, feeder pillars, cabinets, anything at all with cables going in and out of it, don't use for earth. And don't use system earths. Always stick with the old earth pin. We always talk about independent earths, anything that's not related to other services.

26:45Most surveyors have probably lost the earth pin within the first week, and they've probably got an old screwdriver in there now, but... The other thing, these slides show the earth being um in the ground that way round. Most earth pins are like an L-shape. The reason for that is you stick it in the ground that way round so it's just underneath the surface, or even just laid on the ground and pour water on it.

27:12That's the only downside to a screwdriver. The um the rubber bit stops it from touching the ground quite as clearly, but... Yeah, ab- absolutely, Luke. And we actually talked about the last session about using a tree as an earth. Luke just said he's used foliage as an earth, which is, remember on the last one we talked about that, using a tree, branches as an as an earth, Steve, yeah. Yeah, well, um it was on a surveyor course once. We were struggling to get an earth, and there was a tree branch nearby, so I said to the guys, "We'll just use the tree." And they looked at me like I was mad.

27:43The thing you got to remember is a live tree has got a lot of moisture in it, and that gives deep into the ground. So, yeah, you can do that. Um you're going to probably need to use higher frequency. The lower frequency might struggle, but yeah, you can use a tree, tree root, branch, something like that. So, as Pete said, keep your earth nice and close if you want to trace close in. So, in this scenario now, you can do a full 360 around that lamp column

28:11and work out which way that cable's going. As a generalization, the signal will travel from a lamp column, and you got to bear in mind that this is predominantly aimed at how the um systems connected up in the UK. And in the UK, in most residential, city centers, you're going to have a cable feeding a street light column which is fed directly off a main supply. That main supply is coming from a substation, so you can in theory, and I've done it, not always, but you can clip onto a street light column. That will put a signal into the service. It will go down the service to a main's LV supply into a substation. And if you had an HV coming down here,

28:40supply is coming from a substation, so you can in theory, and I've done it, not always, but you can clip onto a street light column. That will put a signal into service. It will go down the service to a mains LV supply into a substation. And if you had an HV coming down here, that will go back through the earthing, and you'll be able to trace the HV. That slide kind of implies that you'll trace everything, which is not true.

29:10But it is a handy way sometimes of tracing other things when you're really struggling. When I was a teenager, we were allowed access, we were given keys. I mean, health and safety's changed a hell of a lot in the last 40 years, but I worked in a 33 kV substation and was told not to touch anything. I guess you wouldn't get away with that nowadays, but...

29:35Spring's here, guys. We've got there a graphical representation of quite a wide range of frequencies. And the one thing that when Radiodetection started producing multi-frequency machines, we said to the software engineer, well, they were hardware engineers in those days, but analog engineers, but nowadays software engineers. We told the engineers just to stick to one or the other, hertz or kilohertz. I'm guessing most of you guys understand this, but when we talk about low frequency, 640, 320, 512, whichever you use, is actually 0.6 kilohertz.

30:18Or if we're talking about 8, we're talking about 8,192 hertz. So you can kind of see the confusion when people look at the numbers and they think, well, 640 is a bigger number than 8, not realizing that it's not actually 8, it's 8,000. This is something which I'm assuming most of you guys understand anyway, but that slide there shows, and the easiest one to count is the, um, the number of peaks or troughs. So, the 8 kilohertz one, there's 8 peaks and 8 troughs there. So if you multiplied that by roughly a thousand, you're looking at 8,000 cycles per second. And before we became European in this country, and, um, probably in the States still have quite a lot of, um, frequencies listed as CPS, and that's exactly how we used to measure it in this country, cycles per second.

31:11So basically, if you look at that on an oscilloscope, you'd have your center line, if I could draw a straight line, which obviously I can't because I'm as bad at drawing as Pete. Um, so 8,000 times per second, or 8,192 if you want to be precise, it alternates from a positive to a negative. I'm assuming you guys are still there because my screen just went blank for a second. Are you still there, Pete?

31:46Yeah, I'm still here. Okay. Um, we've never counted the others. If anybody's really bored, you can if you want, but it kind of gives you a graphical representation of, over the same period of time, how much of a cycle has actually occurred. So if you look down at the 640 hertz, it's not even part of a cycle in that same period of time. So, up at the 131, or obviously if we had 200k up there, you'd have lots and lots of cycles occurring over the same period of time. So what happens is when you start using different frequencies, you end up with, at the high frequency, lots and lots of energy initially. So that means you've got lots and lots of signal. You don't need a lot of current, you've got lots of signal, but because there is so much energy initially, it dissipates very quickly.

32:38At the other end of the spectrum, at the low frequency, 256, 512, if you guys work in the States, we tend to use 320, 640 in this country, or one of the, um, CD frequencies, basically that doesn't divide by 50. Just jump in there, Steve, um, to add to that. One of the problems that we often find in the UK is that we find a lot of surveyors aren't making use of the lower frequencies. They tend to stick to the higher ones, and as, and as Steve said, what you tend to find with the higher frequencies, they seem to be working better because at the beginning, you tend to get a higher signal, if you like. It seems stronger, um, than the low frequency signal does, but as Steve said, it dies off very, very quickly. Um, the low frequency might not seem as good at the beginning, but it will certainly travel, travel, travel further, further down there. And, um, I think on the last one we did, we did a bit of a poll on what frequencies people use, and it was interesting how many people just use 33 or above. They don't tend to use the, the, the lower range of the frequencies. Back to you, Steve.

33:43Yeah, I'm just seeing what Luke's put there. Sorry, I'm going to lean forward, I can't see it on my screen. Yeah, the thing, Luke, if you've, if you're using a comms frame lid for an earth, you've got a very good chance you're going to put a signal into that lid and then possibly into the cables below, because obviously with comms pits, both in this country, Virgin Media predominantly, um, their stuff's very shallow, so you've got cables just below the lid, so you're going to get induction into those, um. Getting back to our frequencies and, um, what we've got on screen here, the best analogy that I can come with is sound. If any of you guys have ever, I don't know, where I live, we often have, um, festivals down at the rugby club. It's about a mile away, and you can hear the music coming from the festival, but the only thing you can hear is the bass. So the low frequency, and if you've been to a gig or a concert, you can feel the low frequency move in the air because it's, it's a much lower frequency, much longer wavelength. The high frequencies dissipate very rapidly. It's exactly the same with a locator. It might sound very loud, very clear to start with, but it will dissipate a lot more quickly. The other downside to high frequencies, and don't get me wrong, they are very useful at times, but the other downside is the fact that they will transfer and cross-induce onto other things a lot more easily.

35:31So this symbol here is the symbol for no earth or capacitive earth. Pete covers on the HSG47 course, and we're not covering it today because I don't think we've got time, but he talks about PME in this country, which is the modern earthing system in the UK, where you don't technically have an earth at the end of a cable, it's on the network somewhere. So if you put a low frequency onto a cable which is jointed and feeding a load of buildings, and it's PME, you won't get a signal traveling down. If you do, then there's a big solid earth. When I started in the 1970s, every house in this country

35:50don't technically have an earth at the end of a cable, it's on the network somewhere. So, if you put a low frequency onto a cable which is jointed and feeding a load of buildings, and it's PME, you won't get a signal travelling down. If you do, then there's a big solid earth. When I started in the 1970s, every house in this country, every building had a big solid earth. You put a signal onto an LV cable, and the signal would go down the cable, and it would go off down to the nearest big earth, which may be at the first property, maybe the middle property.

36:25But you don't get that effect anymore. But what does happen with the lower frequencies, and we're talking we look at 8 and 9.8, those sort of frequencies, around about a 10 kilohertz range as being kind of a a low to medium frequency. There's no actual definition unless you're looking at Wikipedia. But those frequencies should continue down the main and not down services, and very unlikely to transfer onto other things. If you start using higher frequencies, you get the bonus the fact you can actually trace a service to a building.

37:00The downside of that is it's going to jump across onto adjacent services, as people were saying before. You can affect that somewhat by placing your earth away from it if you know there's something else there. But this is the downside. This is the main reason why avoidance devices like the CAT and Genny tend to have high frequencies. This is something Pete covers on his CAT and Genny course, but you've got in a CAT and Genny, the Genny itself is actually transmitting 33 and 131 kilohertz simultaneously, and the CAT's picking them up in the Genny mode simultaneously.

37:30With the V-Scan receiver and transmitter, the V-Scan, which is the vLoc equivalent, simultaneously transmitting 33 and 131, the receiver, you switch between the two. And other manufacturers do the same thing. But those devices are more designed as avoidance devices rather than surveying devices.

38:00Steve, just jump in. I think it's Rowas was saying, it all depends on the area, how congested it is, to not forget to try multiple frequencies. Luke was just saying we use different frequencies depending on the utility we're trying to locate. Absolutely spot on, guys. And that's the thing with where the, you know, the training comes in, if you like. It's not, it's just teaching people what the different frequencies do, which ones might work, which ones might not work, understanding when to change frequencies and that kind of stuff, which you guys get. And that's the idea of having this high-end kit, is you have all these frequencies at your disposal, and you can use any one of them.

38:30So, when I started in the 1970s, the location equipment that we used back then for surveying had one frequency, 3.4 kilohertz. Was it 3.142? I can't remember. Anyway, it was around about the 3 kilohertz range. We didn't have another option. And if I'm being honest, I think I probably located more things deeper with that old analogue stuff than I've ever done with more digital stuff.

39:00The upside of the digital stuff is you can have a whole load of different options and frequencies. And when Pete was in the office the other day, he had the old RD600 on the shelf behind him. That was the first proper multi-frequency machine that Radiodetection produced in the 1980s. It had seven frequencies, from 1 kilohertz up to 130 kilohertz on the active range.

39:30Nowadays, I don't know how many there are on the 8100, I've not counted them, or the vLocPro3, but you've got 30 to 40 different frequencies. You don't need all those frequencies, but a range of low, medium, and high is useful to have, and then you probably switch off the ones you don't use, or you just scroll past them what you don't need. So, as a general rule of thumb, don't forget this is just a generalization, low frequencies will give you a longer range, you get less cross-induction, it's more of a locating frequency.

40:00High frequencies, they are very useful, I keep on saying that. You get much more signal induction, you're more likely to pick up small cables. In the UK, most small comms cables, Virgin Media's an exception, but BT, they're not usually earthed at property. I know in the States that's different. In this country, you don't generally get earths on the end of small cables. So, that means you're going to have to use high frequency to get a signal to travel down them.

40:30And it's back to Pete again. He's going to go a little bit on signals and aerials. You can turn your screen share off, Steve. I should have done that, shouldn't I? Yeah. Sorry. Hi, guys. Welcome to me. So, we're going to cover a little bit now on on antenna settings, in particular, distorted fields and and peak and null, and then Steve's going to carry on covering some of the lower frequencies and and current direction.

41:00Before I start with my slides, guys, I just want to ask you a question. Can anybody tell me the physical differences between a peak aerial and a null aerial? Not what they pick up or what they detect, but the physical differences, if you looked at them both, what difference would you see? Anybody tell me that? I'm just looking at Neil's comment, "sewering", yeah, god, that's an old one.

41:30Maybe should have been a bit clearer with my question. But, um, I'm going to run through it with you anyway, guys. When you when you have your locator on peak, and this is the same way that a CAT works, it's basically using, um, a ho- exactly, yeah. That's what I was trying to get at. Sorry, that's a question badly put, but yeah, it's the actual it's the actual orientation. So, a peak aerial is horizontal and a null aerial is is is vertical. Some locators might be might be a little bit different.

42:00When you're locating a signal, you've got your, I'm I'm used to the old stuff like Steve, so I call it a needle, but you've got the you've got the you've got the signal strength meter, should we call it, but you'll hear me calling it a needle anyway. And as you walk across that that signal, that magnetic field, it peaks, you get the highest point, and then it drops again when you go past it. So, I'm sure you guys all understand that you're looking for the highest signal, and that should equate to where the utility is.

42:30So, what what the what the aerial's actually doing is it the signal response you get from your locator is actually based on the angle of the magnetic field passing through the antenna. Okay? So, I'm just going to turn my screen share off so you can see me a little bit here, but just just imagine that coil there, that's what the aerial is at the bottom of the locator, just so you can see me bigger. If you imagine my my knuckles as being that coil, and I place that, it's all reversed on here, so it's the wrong way. If I place that in the magnetic field, it passes through it.

43:00And and that's why, guys, I'm sure you're aware that if you put your blade of your receiver in in line with the utility, typically, you'll get

43:25And and the way that it works is this, guys. When the magnetic field, the angle is horizontal, the maximum amount of signal can pass through that aerial. So, that's why we'll get the highest reading, where it's horizontal. If the angle of the magnetic field was on a 45-degree angle like this, let's say we'd get 50% passing through. And if the angle of the magnetic field was vertical like this, none of it would pass through. Okay?

43:52Does that make sense, guys? Just just want to get some input into this, so each section I move on to will only make sense if we understand each each part leading up to it, okay? So, that's how a how a peak antenna is effectively working. That's how a CAT works. So, if I just put my my my screen back on with you again here, what you can see here is the um the the peak antenna, the horizontal antenna, and here, it's, oops, get my pen going. Can you see horizontal? 100%. Over here, it's on a slight angle, so it's a weaker signal. Yeah, cool, guys.

44:27So, so let's let's effectively put that in the real world. This is a magnetic field coming off a cable. If I put the aerial here, I'm going to get 100%. If I put the aerial here, can you see it's 45 degrees? I'm going to get 50%. If I put the aerial here, again, 50%. So, that's why I get that peak response. What I also wanted you to see from that diagram, guys, is the highest reading, yeah, the 100%, which relates to the horizontal band, on this situation is directly in line with that cable, okay?

45:03Let's now look at distorted field, guys. So, in an ideal world, the magnetic field coming off an underground utility should be a cylindrical, just like you can see there. However, quite often, it gets distorted. Distortion is caused by many things: bends, T-junctions, multiple utilities, there's a whole host of things that can cause distortion, guys. And a distorted signal would look like this. Now, once again, using our peak antenna, if we look if we put the most horizontal part is probably about here. So, that's going to give me my 100.

45:36If I put the receiver directly over the cable, as you can see here, the angle's kind of 45 degrees, so 50. And over here, 50. So, my response now is like this. So, I'm going to mismark the cable. Anybody ever had that before, guys? I'm sure you have, where you've you've marked something up and it's in the wrong place. You get a mislocate, and it can vary. Does it make sense so far, guys? I will keep asking you for a bit of feedback during this so we can keep moving on to the next section. Okay, so that's how we can get an inaccurate locate from a distorted magnetic field.

46:09That's how a CAT works. That's why we do a lot of training with the guys on site who are who are doing excavations, and they'll often complain that they've mismarked things. Okay, now the difference between a null aerial, guys, is a null aerial is actually vertical. Now, if anybody knows with a null aerial, what you actually if we if we forget the arrows for now, because I know we've got arrows on there to make our life easier, but if we go back to the old-fashioned locators like the old RD400s, the null basically is where you get the minimum response. So, the idea of a null antenna is that you get signal when you're away from the cable, and then as you come over it, the signal drops to its minimum. So, we get no signal where the cable is. And the reason for that, I I hope you can relate to this, can you see the null aerial is vertical?

46:53Okay, so once again, I'm just going to turn my screen share off so I can use my knuckles to to show you this. Imagine the null aerial being like that. If the signal was now vertical, the magnetic field angle was vertical, I'd get 100% reading, wouldn't I, from the null antenna? But when this magnetic field is horizontal like this, how much will pass through? Zero, yeah? Any other angle, like that or like that, I would get a response from the aerial, but when it's completely horizontal, I get a complete zero. And that's what your null antenna is referring to. So, here again, where the magnetic field, oh, I've done it again with my pen. Hang on, let me turn screen share back on.

47:32So, let's go back to here again now and look at the null antenna. Here we go. So, again, the antenna's here, the magnetic field's horizontal, zero. But if I put it over here, it's not um it's passing through it, makes sense? So, let's look at the real world again. If I put the null antenna here, because it's horizontal, I get zero. But if I put it over here, because it's now angled, I kind of maybe get 50, and then over here, um again, sorry, I misdrew it, get 50. So, the null response is more like that. Okay?

48:13So, does everyone understand how a peak and null antenna works? Okay? And do you also see, guys, that the peak and null antenna is going to point to the same place? It's in in effect, it's picking up the same thing. A peak antenna is giving you the strongest response where the magnetic field is horizontal, okay? And a null antenna is giving you the minimum response when the magnetic field is horizontal. Okay? Have we all got that, guys?

48:45Okay, so let me ask you a question then, guys, and forgive the delay. When we have a distorted signal then, if the peak and null antenna are effectively pointing to the same place, why do they give different positions? Yeah, what's the answer to that, guys? Why, if they're actually pointing to the same place, do they give different positions on a distorted signal? Can anybody tell me?

49:20See if anyone can get that one. I'm not sure if you don't know or you're just not answering yet or it's a delay on there, guys, so I'm going to I'm going to carry on and see if any answers come in.

49:41And the reason for it is the position of the antenna. So, if we look at a typical locator, we're going to ignore the top aerial for now. Your peak antenna, which is horizontal, is here, and the null antenna is here. Okay? Okay, got that, guys? So, in other words, the null antenna is higher, all right? So, let's have a look at this magnetic field again. On this one, which is undistorted, the peak antenna is detecting this band, if you like. That's our 100%.

50:10is higher, all right? So let's have a look at this magnetic field again. On this one, which is undistorted, the peak antenna is detecting this band, if you like. That's our 100%. The null antenna, which is higher up, is giving the same position. Even though it's higher up, the angle is still horizontal passing through it.

50:41But let's look at a distorted field. Look at the difference. The peak antenna is here, but the null antenna is higher up, so it would equate to here. Does that make sense, guys? If you look at it, the deeper something is, the further away those horizontal bands come. And because the peak and null antenna are at different heights, that's what gives us that offset. Does that make sense to everybody? And this is also, guys, me and Steve spoke about this last week. This is also why sometimes the peak and null response from different locators is slightly different. It depends on the distance between the antennas. Some are closer than others on it.

51:17Okay. So, does everyone, is everyone okay with that, guys? It's obviously quite technical, this bit, but um, I hope you understood that. So, that's why when we have a distorted signal, guys, what we actually get is this. We get the true position, the peak position, and the null position.

51:35Okay. And one of the, one of the interesting things is, guys, you know, we get this with beginners quite a lot, is if peak says it's here, and null says it's here, a lot of people think it's in between. And it's not. It's on this side of the peak. So, you kind of get cable, peak, null, or cable, peak, null.

51:54One thing that you will always notice, guys, is which is always furthest away? Null. And the problem with that is that because we use these little left-right arrows on null, people often think it's more accurate, and it's not. Okay, it's not. It always goes further away. There was a rule basically saying that you could kind of work out this position by some, some theories say half this distance, some say a third of this distance. I would not bank on that, guys. There's been many a situation where that's not been true. You'll, you'll usually get that layout, but this to this, I would honestly say, have a very cautious about putting any exact figures on that distance.

52:28Um, I hope that was useful, guys. I hope that, that, that made sense. Um, and now you understand about the different, um, peak and null antennas in the machine. Some of the locators work slightly differently, guys, but that's in effect what we get from distorted signals. So, just to summarize, if peak and null are in the same place, it generally means we have an undistorted signal, generally means we're going to be accurate. And that's why we do that peak and null test before we take a depth reading. If peak and null are separated, we've got distorted field.

52:57And then we need to look at correcting that, guys. This is the other thing that we find, is that people kind of accept that and start guessing where it might be. Let's look at changing frequency, changing earth position, uh, changing connection points, but the first thing we must do is try and correct that signal, not just locate with a distorted signal, if possible. Hopefully that makes sense, guys.

53:17Just before you go back, go back to your, um, one where you drew your triangle, Pete, on your, um, distorted field, because

53:26Yeah.

53:28So, you, as I'm looking at it, the one to the right-hand side would actually be narrower than the one on the left-hand side. You remember

53:38Absolutely. And this is another point, guys, that we talk about in more detail, because there's multiple ways of, of looking at distorted, um, signals coming off it. We use peak and null as one. But what you tend to find with an undistorted signal, you get an equilateral triangle. I'm crap at drawing triangles. With a distorted signal, you might get more kind of like that, if that makes sense, guys. And we can do this with a basic CAT as well. We can look at the, the angle of drop-off.

54:02Uh, just before I pass you back to Steve, Steve's going to talk, start talking now about current direction and current measurement. Um, I'm not sure if you guys have used these before. Um, so, anyone used current direction out there? And I want, and we want to talk about the importance of, of these high-end features on your locators, because again, we feel that they're underutilized.

54:21So, I'm going to show you an example, which I've already touched on, and then Steve's going to relate to this as he talks about the next section. A very simple example, um, plan view looking from above. I've got my pipe, if you remember. Okay. And I've, and I've hooked my transmitter up to the pipe and put the earth here. Okay. And then I've got a, a parallel utility.

54:49Now, in theory, with a locator, whatever we hook up to should give us the strongest signal. If we've got a return signal that's bled onto something else or coming back down something else, in theory, that signal should be weaker. Okay? So, what we've got here is we've got signal traveling down here, and we've got it kind of coming back down here. Going to keep it nice and simple, guys, yeah. If both those utilities were at the same depth, we would generally get a stronger signal on this one. However, that's not always the case, is it? So, like I said before, let's imagine that this is a meter deep, and this one is only 300 mil deep.

55:23What could effectively happen now is that this one from the surface is giving us the strongest signal. So, we end up tracing the wrong line. Okay. This is a problem that we have. This is where current direction and current measurement come in to help us figure this out. And I'm going to pass you back to Steve, who will expand on current direction and current measurement. So, I hope that section was useful for you guys, that I've just covered. You ready, Steve?

55:52Yeah, sorry about that.

55:55Your screen share back on, mate, and it's back over to you.

56:01Yeah.

56:19I don't know if you guys can still hear me, but, um, it's hanging at the moment. Apologies for this. It's just suddenly gone, um, grayed out. Are you still there, Pete?

56:30Yeah, mate, still here. Still here.

56:33Yeah, mine's just hung for some reason. Sorry about this.

56:51We can see your slideshow, mate, so we can see you.

56:55I can't see anything.

57:03Do you want to jump back in? Hang on a sec. I'll just see if it works. It's just, I can't get rid of the, um, here we go.

57:13Yeah, it's working, mate.

57:15Yeah, okay. My second screen's just hung for some reason, but never mind. We'll carry on, guys. Current direction, signal direction, or signal select. So, RD, Radiodetection, developed current direction. It was originally in the old RD400 range, so 20-plus years ago. And one of the main issues we always had, and

57:20We'll carry on, guys. Current direction, signal direction, or signal select. So, RD, Radiodetection, developed current direction. It was originally the old RD400 range, so 20-plus years ago. And one of the main issues we always had, and this mostly came about through working with AT&T in the US, was trying to actually make sure you were tracing the right thing.

57:52And over distance, even the lower frequencies, you did get to a point where you started to get return signal, and it was sometimes very difficult to determine which was the right one. So, RD engineers developed current direction, and it was a methodology where you could actually trace out normal, but you had a separate identifier. I don't know if you guys... my second screen's locked, so I'm not sure I'm getting any responses, but, um,

58:20I don't know how much you guys use CD, SD. CD and SD is pretty much the same thing. SD is Vivax's version of current direction, they call it signal direction. And SIS is signal select, which is a much wider range of frequencies doing pretty much the same thing. Very useful in congested areas or for long-distance tracing, and you want to make sure you're on the right thing.

58:45Aside line, one of the things I do in my business just to keep, um, keep the bills paid and keep the grey matter working is that I do cable fault detection, and I would never consider taking a machine out to do a cable fault without CD or SD or SIS. And the main reason for that, the first and number one rule of cable fault detection is that you locate the cable.

59:09And you've got to be on the right cable. I've had pretty much stand-up arguments with people who are convinced they know where the cable goes, and when you've got a CD or an SD or an SIS signal on it, you can categorically say, "You're wrong. The cable doesn't go there. It goes where I'm telling you it goes." So,

59:28you can only apply current direction or signal direction using direct connection leads or a clamp. SIS on the Vivax, you can, and they probably won't like me for saying this because they they do actually sell an SIS clamp, but you can actually get the SIS frequency to, um, work using a standard clamp. You can't with the RD kit. It's got to be a dedicated CD clamp. And that's it.

59:55Here you go, Steve. Just going to jump in a second, guys. Just to be clear for anyone that doesn't know, CD's a frequency, in effect, and it's a low frequency. So, the same limitations apply. You have to be able to get that frequency onto the utility. And to do that with a clamp, you need that big whacking clamp. Um, even with connection, you know, it's treat it as a low frequency. You need that good connection.

60:27Just keep talking, mate. I'm just going to have to, um, close down the browser because it's gone off my screen altogether now. Oh, we can still see you a little bit. Can you? Yeah. I can't, um... You might have to re-log in if you leave. Sorry about this, guys. I can't screen share. It's just gone off. Yeah. Just re-log in, Steve. I'll hang on till you log back in. Guys, just

60:50bear with us for two secs. If you want a quick toilet break, um, just run to the toilet. Yeah, my browser's hung. We can still see you, Steve, but, um, you might want to leave the room and just reconnect. I can't leave it now. I'm going to have to close it down manually. And he's gone.

61:31There we go. You've just have me now, guys. Any Any questions, guys, while Steve's just just reconnecting? He's going to run through, um, current direction with you when he when he gets back. As I just mentioned before, um, we have to understand that it is a it is a frequency.

61:54You are still there, guys, yeah? I'm just hoping nobody else has disconnected. We've got 62 on, and when there's 62 on, the delay's a bit worse. So, when we're when we're running these for real, if you like, there's a paid course, we'll be limiting it to kind of four or five people, which makes it a little bit easier.

62:17He's back in the room. Hello. The problem we have is that Steve doesn't mix very well with technology anyway. Did you hear that, Steve? Sorry.

62:39It's nothing to do with me. It's the system. Bring back Windows 95, that's what I say.

62:58Okay, that's... Sorry about that, guys.

63:17So, you have the RD kit, and you're going to use, um, CD on cables. You're going to need one of those things. The downside to that thing is it's only 3-inch diameter. So, if you're working in areas where you've got larger cables, um, Vivax make a larger 4-inch, um, 100-mil CD clamp. The only downside to any of this is it's all very expensive accessories. None of these manufacturers send it as standard bit of kit, but...

63:51So, on the RD kit, 8000, 8100, you're going to scroll down to the frequency, um, you're going to choose. They tend to use in the US, um, 512, um, 256. And we started talking about that when, um, when Pete jumped in with some of the, um, observations. One of the main issues with any low-frequency machine

64:24in this country or anywhere in Europe, I'm guessing you guys know this, electricity is generated at 50 Hz. So, if you get any multiple of that, it's called a harmonic. So, any multiple of 50 is kind of easy to work out: 100, 150, 200, 250. So, if you get a multiple of...

64:30anywhere in Europe. I'm guessing you guys know this. Electricity is generated at 50 Hz. So if you get any multiple of that, it's called a harmonic. So any multiple of 50 is kind of easy to work out. 100, 150, 200, 250. So if you get a multiple of that, then you're going to get a harmonic. So around about the 512 or let's say 256 region, if I can get my pen working again.

65:10So fairly simple math, you multiply that by five, you've got 250. It doesn't take a huge amount of frequency shift to get that up to close to 256. You shouldn't really be getting 51 Hz, but you're probably not getting true 50 Hz in this country.

65:34So what we tend to find is around about the 256 frequency in this country in Europe, we get a huge amount of interference from cables. Just standard power interference. And it's not really interference, it's just picking up the harmonic. And conversely in the States, because of electricity being generated at 60,

66:01you start multiplying that by 10, 11, 660, 600. So you're getting close to the 640 range. So in the US, we tend to not use anything that's close to being divisible by 60, and the same in the UK and Europe, or anywhere where it's a 50 Hz system, it's a multiple of 50. Yes, Pete.

66:27Yeah, I was just going to say, so that's why, guys, um, when we when you talk when you hear low frequency being used in the States, they generally use 512, um, and 256, um, for the CD. And in the UK, we use 640 and 320. Hope that makes sense. That's why we have different low frequencies for the US and the UK.

66:47Yeah, yeah, um, is it worth So, the the the clamp basically would go around an insulated cable when it's exposed. So, um, easy example is imagine a a trial hole with a cable exposed in it. They don't work on lamp posts. Um, there was a big thing that went round about this with the bloody gas industry. They started calling them bloody column clamps and putting them around columns, and they and they don't work. You The only way you'd use it on a lamp column is is by going into the column, taking the door off, and then clamping around the cable inside it, which most people aren't qualified to to do out there. So, it's got to go around the cable. Generally speaking, that cable has to have an earth both ends, again, to create that that that circuit. Um, you can sometimes get round that using using high frequency. Uh, back to Steve again, who'll carry on with the CD.

67:33So, the the key thing with um with CD or SD or S-A-S is ensuring you are actually getting the signal in the right direction. I know it's a a bit of a contradiction in terms because you don't have a directional signal. Um, basically, you've got um two signals being transmitted simultaneously. So, this is why we're talking about 512

68:00and 256. The carrier frequency is the higher of the two, and the identifying frequency is the lower. So, you'll always find it's half the carrier frequency. So, 640 in the UK or Europe, if you're using that one, half of that's 320. On the 8000, if you guys are using that one nowadays. And the other thing is you've got to make sure you've got the right model. Um,

68:26I would go to full screen, but I'll probably mess it up. So, RD8000 PDL. In the 8000 range, there's only two machines that have CD. That's the PDL and the PTL. There's quite a lot of different um models of 8000, but there's only two can actually um receive CD. The TX-10 transmitter is the only transmitter you need.

68:56Um, I know again there's a wide range of transmitters, but stick with the high-powered transmitters. A TX-1 and a TX-5 look exactly the same as a TX-10. The 1, 5, and 10 is the power output. And if you've got a TX-1, you don't have CD. So, and you've only got 1 watt of output.

69:20If we've got time, we'll talk about transmitters and how to get more power out of them, as well as messing around with earth earth placement. There are ways of getting more power out of a transmitter if you're struggling. So, you choose your CD frequency, and you've got to make sure that your current direction is in the right direction. If this is working,

69:44What? What? What? What?

69:51Actually, I'm going to skip to that slide, and we'll come back to this one in a second. The next one's a a video from RD just explaining a little bit about it. I'll turn up the volume as well so you can actually hear a little bit more clearly.

70:03Current direction allows you to identify your target line amongst a number of parallel utilities by applying a specialized current direction signal from the TX transmitter. A directional arrow is displayed on the locator screen, confirming that you are tracing your target line. An icon on the locator screen shows which frequencies support current direction. It is always good practice to reset current direction before use.

70:26This can be done by a sustained press on the F key for any of the current direction frequencies. To verify current direction, you can build a small circuit using the red and black direct connection leads from the TX transmitter. Set a CD frequency on the transmitter, and point the receiver toward the red clip. The CD arrow should be showing current flowing toward the red clip.

70:48If this is not the case, use the current direction reset option, and the arrow should then start pointing in the direction that the current is flowing. To verify, switch to the black lead. The directional arrow will now reverse.

71:06Turn that one slide, guys. That's an old Steve, can I just jump in for a second there? Yeah, yeah. Just turn your screen share off for a sec.

71:19So, guys, just to um jump in before Steve gets to the technical side of it, remember the example and the problem that I gave you before. Um, I'm just going to I'm just going to redraw it very, very quickly.

71:34Which will hopefully help anyone that's new to CD understand what it's doing. You remember the problem we had, we had this pipe here that was a meter deep, plan view, and then we had this other utility that was quite shallow, for example. And then we'd hooked up to this, and we had signal traveling up here and back here. Now, we're trying to locate that pipe. The problem we have is that we've got multiple signals, and we're not sure which is ours.

71:40And we had this pipe here that was a meter deep, plan view, and then we had this other utility that was quite shallow, for example. And then we'd hooked up to this, and we had signal traveling up here and back here.

71:54Now, we're trying to locate that pipe. The problem we have is that we've got multiple signals and we're not sure which is ours. Okay? So, whereas before this one had the strongest signal on it, what will happen now, the arrow you just saw on the locator will point away from the transmitter. So, when you put your locator over this one, it'll point away. Any return signal will have an arrow pointing back.

72:17So, even if I had multiple utilities, all with a return signal on it like this, every one of them would have an arrow pointing back. So, let's say we've got the four, four signals. One of them would point away, the rest would point back. And that's how we start identifying that we're on the right target line. Does, is everyone with us so far on this, guys? Are you understanding the benefits of, of CD? And Steve's going to again talk about it in a little bit more detail.

72:37Um, on that note, guys, I'm sorry, I have to leave you. Um, I have to go to a, to, to a rather important meeting. So, I'm going to leave you. Um, Steve will update you on the rest of the sessions that we've got, um, at the end. If you've got any feedback on today's, guys, drop me an email. I hope it's been useful so far, and I'm sure you'll enjoy the rest of it. Um, and I'll pass you back over to Steve, um, and I'll see you all later. Thanks, Pete. See you soon.

73:06[no speech] Just while you've got me in, um, large screen, you showed on the RD video...

73:25...pressing and holding the frequency key on the 8100 to reset CD. On the 8000, it doesn't do that. What you have to do is you have to go into the sub-menu. I'm seeing this backward, I'm guessing you guys are as well. Sub-menu, momentary press, and you scroll until you see CDR.

73:50That stands for current direction reset. The one thing I don't think it made clear on that video is whenever you do a current direction reset, you've got to make sure that your back is to the transmitter, and this bit, it did say point this towards the red lead, but you've got to make sure that this is always pointing in the direction you think the cable is going. So, what we tend to do is check it on the red lead initially, but you've got to make sure that that is pointing in the direction of the cable...

74:17...or the pipe, not back towards the transmitter. If you do a CD reset with it in the wrong direction, you're going to get the arrow the wrong way around. Pete's last little scenario, you kind of twig straight away that something's not right, because you'd have loads of away-facing arrows and one facing back, and that will kind of make you realize that CD's the wrong way around. But the easiest way is always on the red lead. The difficult thing with CD is when you get a signal clamp. The main reason for that...

74:52...a signal clamp can go that way around a cable, or that way around a cable, and it does make a difference. On my clamp, I've got a little arrow, which I've put on it using a permanent marker pen, which is fine so long as I don't change transmitters. But, so that way, with a signal clamp with an arrow on it, you always know to point arrow downwards as the cable goes into the ground or goes away from transmitter.

75:17If you're not sure, your best option is to put it round a cable where you can actually see where the cable's going and make sure the arrow is pointing in the right direction. Let's get the screen share back on again. So, the thing with the 8100, it's very quick to do a CD reset. With the 8000 PDL or PTL, you've got to go in the sub-menu to do it.

75:42On the vLocPro3 series, it's a momentary press, I think it's i-key and then momentary press of antenna key, if my memory serves me well. Having been in lockdown for a while, it's been a while since I've been using the kit, so. So, that little slide there, this is the universal symbol for a transmitter. Except I've lost, um, my drawing tools, here we go.

76:13So, that's the universal symbol for a transmitter. So, this would be a red lead connected to a cable. This would be a black lead connected to earth. And this is simulating an excavation, trial hole, cable pit, whatever, where you've actually got three utilities.

76:35Let's say they're all cables, they're all the same color, they're all the same size, and you want to know which is which. So, you walk across it with your receiver, you might be getting multiple signals. Usually, with CD and low frequency, you're going to have your strongest signal on this one, but possibly you're getting fairly similar signals. The benefit of CD is you're looking at your screen, and you're going to have your arrow pointing away on this one.

77:10And on the other two, your arrow points back. If you guys are using the vLoc2, you don't have an arrow, but you do still have the same thing. So, in your compass direction indicator, you've got two hemispheres around your compass direction.

77:27And basically, that equates to this hemisphere lighting up, and arrow back relates to this one. So, instead of an arrow, it's just the semicircle hemisphere, whatever you, whatever you want to call it, lighting up as your direction indicator. On the vLocPro3, you got a nice big arrow shows up on screen, so you can't miss it. I don't know if you guys, I'm assuming everything's back up and working again now. I don't know how much delay there is on there. How much do you guys, or do you guys use CD a lot, or at all, or never?

78:05One of the questions we, we asked at the first session we did last week was what frequency did most people use for tracing. And I guess it kind of depends on what you're doing, but do you guys have a preferred frequency? Do you use CD? While you're scribbling your answers down if you can, if you notice on this trial hole, excavation, cable pit now...

78:31...you've still got three cables. You would assume that the middle cable is still the right one. As you can see from that scenario there, they've now changed position. So, this is the one with the arrow pointing away, the other two cables, arrows pointing back. This is one of the benefits of CD, and this is why I always use it on cable fault detection. Um, only because...

78:50So, this is the one with the arrow pointing away. The other two cables, arrows pointing back. This is one of the benefits of CD, and this is why I always use it on cable fault detection. Um, only because every time you do a cable fault, and there's a very good book, if you hunt it down on the internet, it's written by an old...

79:20...CEGB engineer, Barry Clegg. And he opens up by saying there are only three types of cable fault: a complete open circuit, a complete short circuit, and everything in between. And 90% of what we trace is the third one, the ones that are in between. But the most important thing is you've got to know where that cable goes, and you've got to be 100%...

79:46...certain you know that cable is the right one, and it's the right route that you're tracing, otherwise it's a complete waste of time. So that's why I use CD a lot. It's also, it just takes away the confusion. There will be times when even CD causes problems, just because of other signals, mostly 50 Hz or 60 Hz in the US.

80:15So, Stefan, yeah, you've got a normal signal clamp, so if you're using RD kit, you can't apply CD. If you're using Vivax kit, you can apply SIS. Um, yeah, Martin, earlier... CD's not something you have to use all the time. It's one of those, like every other tool in your armory, it's just a useful thing to have. You may be on sites where you don't often need to use it.

80:48On the RD8100 and the TX10 with the latest version of software, you might notice that there's a 4 kHz and 8 kHz CD. That's very, very useful when you can't get the low frequencies to travel, or you're struggling with 50 Hz or 60 Hz interference. Um, if there's anybody from Vivax on here, they can tell me the highest frequency on the vLoc3 with SIS. I think it's around about the 35 kHz range. So they've, they've taken SIS beyond the normal frequencies up into the higher frequency range.

81:24And that's again down to one of the problems we tend to have with the low frequencies. When I was talking about frequencies earlier on, low frequencies are always preferable in identifying or tracing situations where you've got congestion. But the downside is 50 Hz or 60 Hz interference, and you need more power from your transmitter.

81:48So, you may find that you're trying to use low frequency or CD, and you're just not getting a clear enough signal. So, both RD and Vivax have now made receivers that can receive higher frequencies and still have the benefit of CD or SIS, which is the same thing.

82:10Current direction on. So this is very similar to the slide that Pete then drew in. To answer your question, Jason, um, will CD work on HV? Yeah, you're going to have to have a CD clamp, that's the only thing. Um, and some HV cables are too big.

82:35This is something that we said all along when RD produced the CD clamp initially, that the clamp was too small. So Vivax have got a 4-inch, I believe, 100 mil, um, CD clamp and an SIS clamp. Receiver clamp... you can get a CD receiver clamp, or you used to be able to, but I'm not sure you can anymore. You can certainly get a CD stethoscope.

83:04Um, in this country, although we've used it numerous times for cable identification, it's not an approved method. The main reason for that is there are, um, instances when you can get it wrong. Certainly with a signal clamp, you can get the clamp the wrong way round, that's the simplest way of getting it wrong.

83:21So in the UK, and different countries will have different, um, legislation, but in the UK there's only one approved method for cable identification, and that's, um, putting a transmitter across two cores which are shorted out at the far end, and using a very simple receiver with a small stethoscope-type aerial which you run along the cable and you pick up the twist of the cable, the lay effect as it's called. So we don't tend to use CD as an identifier, although you can.

83:51Marty saying yours is fro- frozen, I'm guessing you're talking about your screen, but, um... Stefan, to answer your question, I don't, I have got the, the RD price list, but I think you're looking around about the 6 to 700 pounds in the UK. So I'm guessing that's, um, if you're overseas, um, sort of exchange rate at the moment is probably around about the same, 6, 700 dollars or euros for a signal clamp.

84:30So the scenario we've got there up on screen now, your transmitter would have been applied down here somewhere to this one, with your earth pin, and you're getting return signals on underground services and on crash barriers. Any long metallic structure just acts like a normal cable or pipe, any conductor. So you do get signals from crash barriers, it's a known issue. If we get time, we'll talk about that a little bit later on, but...

85:07Pretty much every machine nowadays has got current measurement, and it was, um, initially sold as a, a method of identifying before current direction came out. If you guys have got any specific questions, I know I'm skipping around subjects, um, only because mindful of time, we ran out of time last time, so, um... If you've got any questions, by all means pop them up on screen, and I'll try and answer them as we're going through.

85:36So the idea of current measurement is you're looking at the signal that you've applied, and the machine's popping up on screen with an, an indication of which has got the most current. So in the scenario there, it's not the most accurate graphical scenario because it probably wouldn't be very accurate anyway, but the idea is you've got your target line down here, you applied your signal, this is not using CD now, this is just using CM, current measurement.

86:05And you've got a stronger signal here than on the one you think it is. And you've got a slightly weaker signal over here. So the idea with current measurement is you're actually looking at the current response...

86:31If those utilities were about double those distances apart, then that would probably be okay, but that close together, I certainly wouldn't rely on current measurement. It is a very useful function, though. Again, we use it on cable fault detection, pipeline monitoring, and just looking to see where signals split.

86:52So, Pete does quite a lot of sessions on CAT and Genny throughout the week, basic type tracing stuff. And although you don't with the standard CAT, you do with the V-stand receiver, you do actually have current measurement on the V-stand receiver, but on the standard CAT, you're just looking at signal strength, and you're looking at where your signal's changing and splitting.

87:12So, the idea is you put a signal onto whatever you're trying to trace, you pick up a receiver response, and then you look at your current. When I was a teenager in the 1970s, we didn't have current measurement. We had the old-fashioned needle responses, with a big moving coil meter with a gauge on it from 0 to 100.

87:32And we were taught to religiously set the thing to 70%. So, you set your needle to 70% and you watched it. And if you got any change of signal when you went back over it, that indicates that something's happened to your current.

87:48So, it may drop down to half, it may drop down even further than that, it may go up. But once you saw that change of signal, you knew something was happening. On the modern receivers, you've got current measurement. All I've got is an 8100 with me. So, only got standard 8000.

88:09So, on the 8000, your current measurement is indicated down here where depth would normally be shown. And to switch between the two, you press and hold the aerial button. So, if you're not seeing current and you want to get current on screen, you hold the aerial button down and it switches over to current. If you've got an 8100, which Pete had in the background when he was with Sygma,

88:33on the 8100, you've got current and depth shown simultaneously. So, on this side, where you've got frequency on the 8100, it alternates between frequency and current, and on this side, you've got depth. And on the vLocPro3, you've got depth and current, again, simultaneously shown on screen.

88:53So, I said to you before, the idea is it shows you where your signal's going and what's happening to your current. I wouldn't use it, as that slide says, if they're close together, but if you've got a reasonable separation between multiple utilities and you're still getting signal on three of more of them, theoretically, the strongest amount, or the highest amount of current, will be the correct pipe or cable.

89:18Yeah, Bill, you put on there, you've used it for locating cable joints. Yeah, um, so you're following your signal, your signal will always change when you get some sort of connection on the cable, a joint. Sometimes it's very obvious, sometimes it's not.

89:38But this scenario, or this slide here, explains how current measurement works. So, you've got a 90% signal strength reading on your screen, you've got a depth of 0.6, and your current measurement is showing 25 milliamps. You've walked down the route of the cable and it's gone a lot deeper, it's gone down to a meter down, so your signal strength's dropped from 90 down to 30%.

90:02If all things are equal, your current doesn't change because that's how it does it. It's calculating, and don't forget, it's a made-up number. You're not actually picking up 25 milliamps because that's impossible to actually measure, but um, it's giving you an indication how much current is being given off by the pipe or cable. In that situation there, its signal strength dropped dramatically, but your current stayed the same.

90:28If, and this is maybe what um Bill's talking about, if this was a cable and we had a joint here, and we had a cable going off over there, your 25 milliamps, if all things are equal, could end up being 12 and a half going that way and 12 and a half going that way. It's again something we tend to use where cables are jointed and you're looking to see where your signal is and what's happening to your signal.

91:02So, in simple terms, your signal's coming down here, 25 milliamps. On a plastic insulated cable that Pete was talking about, you're going to get very minimal loss over distance, unless it's really long distances. So, 200 meters, you're not going to see a massive amount of loss of signal unless there's a joint or a connection or something's happened to it. So, you can monitor which way your signal's going by looking at current measurement.

91:30I'm hoping that makes sense to you guys. It's also something that we use on pipelines. I spent a lot of work, um, in the 1980s and '90s, um, with a guy who was the the guru in this country for pipeline corrosion control, guy called Graham Gedge, who worked for British Gas and, um, lectured all over the world on corrosion control.

91:55If you guys have ever done any, um, pipeline, um, monitoring, the old tried and trusted technique was what's known as a Pearson survey or CIPS, Close Interval Potential Survey, where you're putting probes in the ground and you're looking at, um, the earth soil potential, which, um, with a coated, protected pipeline,

92:25and I can't draw straight lines. So, you've got your pipe, which is like, just like a cable, insulated, and it's steel and it's welded, so electrically, it's as good as you're going to get. But let's say a farmer's put a fence post, because in this country, it may be the same in the US, but in this country, a lot of damages tend to happen on farmland, even though the farmers know they're there.

92:51So, he's stuffed a fence post in the ground and he's taken off a big chunk of the insulation here. So, let's say this was per kilometer. The old-fashioned technique would be that you'd walk along the tube with your ski poles, your probes in the ground, and you're looking at the potential measurement between the pipe and the ground around it.

93:23This was obviously very time-consuming, took a lot of man-hours to do this, especially on long-distance pipelines over distance.

93:24This was obviously very time-consuming, took a lot of man-hours to do this, especially on long-distance pipelines over distance. Um, so we learned very quickly that you could use low frequency and use current measurement to look at a linear loss of signal.

93:40So if you've got a chart of loss over distance, it tends to be reasonably linear.

93:52These numbers are a bit low, but let's say for simple maths we'll stick with them. 100 milliamps, 1 kilometer, 80 milliamps, 2 kilometers. So this is fairly linear, we're getting 20 milliamp loss per kilometer.

94:06And the other thing about this is you don't have to walk the entire route. You jump in your car, van, truck, and you drive to a road crossing or a point where you know roughly that you're another kilometer away, or, in the States, miles away.

94:21And you suddenly find that between three and four, at our 4 kilometer point, we've now only got 20 milliamps. So at this point here, we've lost 40 milliamps.

94:36So if you map this in loss, 20 milliamps, 20 milliamps, 20 milliamps, 40 milliamps.

94:46So you now know that between kilometers three and four we've got a significantly higher loss of current. These numbers would be higher anyway.

94:55What you can then do is you can then walk that kilometer looking for any obvious indications, farmers putting fence posts in, um, it could be another utility crossing it. You can use an A-frame, a PCM device, every manufacturer, most manufacturers anyway, make machines for picking up these contacts. Even just a standard locator will probably pick it up.

95:17So, that's where current measurement is very, very useful. I've done lots and lots of, um, tracing like that. I don't know if you guys do pipeline monitoring or anything like that, but that's where you'll find current measurement useful.

95:37We debated where to put this slide in, and it's been moved around a few times. Um,

95:43This was before the 8000 came about, so it was in the old RD4000 days. I went over to Scotland with a surveying company who were being tasked with remapping, um, Scottish Water's assets, and they'd had some issues with, um,

95:58where they'd marked, where they thought the pipe was, and it turned out not to be correct. So they, they decided it was a training issue. There was a combination of factors. I went out with this surveyor, a pretty experienced guy.

96:10In the UK and the US, um, Metrotech was a very common manufacturer. Metrotech are now owned by Vivax, big, big manufacturer, um, very well respected in this industry.

96:22In the US with big wide open spaces, the old Metrotech 810 was a great bit of kit. Um, very widely used. If my memory serves me well, it was 83 kHz. So quite high frequency.

96:36Auto gain.

96:40And in the UK, a lot of guys working in the water industry were using Metrotech equipment. In tight Glasgow streets, same as anywhere in the UK and Europe, the high frequency and the auto gain wasn't quite so good.

96:57So I took this guy to one of the sites he'd had an issue with, and he, um, I just left him to it. I said, "Show me what you're doing." So he connected his transmitter up as the slide shows there.

97:09He put his earth in the grass verge over here.

97:13So going back to what we'd said earlier on about earth position and what we cover on day two of my survey course, talking about electrical circuits, where's the electrical circuit there, and what's the issue with that?

97:26I'm assuming you guys are still there because I can see some numbers up on screen, so...

97:32Um, the other obvious thing to say about water pipes, and certainly in the northern part of the States, this is an issue that I found, and I'm guessing if any of you guys are from the northern part of the States, you'll know this, or Canada, because of the permafrost and, um,

97:50temperatures in winter, you can have, um, water pipes at significantly greater depths. So, I moved south when I lived in the States, I moved to Houston, so freezing up of, um, water pipes wasn't so much of an issue.

98:08Yeah, Joe, you're absolutely right.

98:14So, you clip onto a water pipe, and this is what this guy did, I think it was a hydrant or a valve, shoe line go, I can't remember.

98:22And it was close to the road edge.

98:25And the other thing to say about water pipes, um,

98:33in this country, there's a, a very common ductile type pipe, and it's called a Tyton connection. So, I'm a bit like Pete, not very good at drawing. So you've got like a male-female configuration, and inside the bell housing is a rubber O-ring.

98:49And your other bit of pipe sits inside it like that, and it sits on that rubber O-ring. So, you've got an issue with electrical continuity. Ductile's not a very good conductor.

99:01So, let's say these are 5-meter sections of pipe. The other issue, besides the fact, um, we've got these rubber O-rings, this pipe is bare metal anyway.

99:14So your signal travel...

99:17Yeah, Neil, you're right. You've got your earth near to other services. This is the major issue with this. Remember AC, alternating current, something we cover on the survey course, explaining about AC and DC, not the band.

99:32Probably find it more interesting than me rambling on, but anyway. So, we've got signal going in all different directions. We can't stop it doing that.

99:43And because this is a bare metal pipe, instantly we're getting loss. We're getting signal return going across here.

99:54There becomes a point where the path of least resistance for this current, whichever frequency we're using, is to actually travel down adjacent cables.

100:04So we've now got signal traveling in both directions on adjacent cables.

100:14Let's say for simple maths, we're getting 100 milliamps from our transmitter, and if all things are equal, that means we've got 50 milliamps going in both directions.

100:26And let's say, again for simple maths, at each joint we lose 10 milliamps. We've straight away lost 10 milliamps at the first joint. You can see what's going to happen, guys.

100:46And that's assuming we're getting no loss, which is also not true, but for the purposes of this, it just makes it a bit simple. Yeah, Michael, that's, that's the problem. Um, well, that was his initial problem. Combined with the fact he was using 83 kilohertz and auto gain.

101:10So, if you guys have ever seen the old Metrotech, you've got a centre-sprung needle. And it veers to one side and it's continuous to the other side. So, as you go across it, you're looking for that needle to center out.

101:30You have no gain control on that thing. The machine automatically adjusts the gain. So, as he was tracing on down here, he was getting the correct location, correct location. The machine's automatically adjusting the gain, so he's not noticing the fact that the signal's dropping. You get to about this point, and his signal starts to do this.

101:57Because what he's got over here is he's got about 5 milliamps returning, but it's not just returning, it's traveling in all directions on the other cables. In this case, let's say electric cable.

102:15So, as he started to gradually head across the pavement in this direction, I said to him, "You've got to stop now." He said, "Why?" I said, "Because you're no longer following the cable, the pipe." He said, "I am, because that's what I'm connected onto." I said, "Firstly, you've got another valve hydrant up here." He said

107:30My RD4000 on it was CD. We still had the same scenario where the signal eventually did transfer enough onto the cable that we got a stronger signal. The other thing you've got to remember is the cable's shallow, or shallower, than the pipe. So, a water pipe down around about 800 down, electric cable 400.

107:55It doesn't take long for that signal to suddenly become stronger. But with CD, even though it's an AC signal, this is where you are looking at your arrows, and this is where you are getting this effect. So, your arrow indication is always going to be pointing away. Your return signal is always going to be pointing back.

108:16So, even though we ended up with stronger signal on the electric cable, we knew it was the wrong one because of the arrow direction. And this is, again, where current direction, signal direction, or CD is very, very useful.

108:29Um, there is an old tried and trusted technique, which I was taught as a kid. And when I worked at Radiodetection, when we, we had location in those days, um, when we had all our kit sent up, it was a surveyor kit with every conceivable accessory you can imagine. And one of the most useful bits of kit was a 300-meter extension cable. And what that allows you to do is that.

109:02So talking about my stage two surveyor course and electrical theory and electrical circuits, what's your electrical circuit now? On the previous two slides, the electrical circuit involved using the earth ground as part of your circuit. And this is the bit that people tend to forget about. You've put your red lead on what you're trying to find, you've put your black lead in the ground to the earth.

109:25That whole mass of ground is part of your electrical circuit, and anything else that happens to be in there also becomes part of it. So, if you're working where there's old tramlines, railway lines, that's part of your electrical circuit, fences, um, even a large vehicle parked alongside you will carry some of that signal and become, if not part of the circuit, certainly inducing some signal. But what happens in this scenario here, guys?

109:56Yeah, Bill. Total copper. Double-ended connection. It's the old-fashioned but probably best technique for tracing anything you could possibly ever want to trace. There's obvious downsides to it. Firstly, you need a 300-meter cable or longer. Secondly, you've got a long bit of cable with trip hazards.

110:20There's one very good reason why we run it across the road and down the other side, and that's to get it away from all the other services. Because that cable is generating a huge magnetic field. If we're using low frequency, as you know from experience or what we've been talking about, the lower frequencies are less likely to induce into things.

110:44In the old days of the analogue kit, they used to say, um, move the cable three times the depth. With digital kit, I would say make sure it's further away. That cable, within reason, could, can be as long as you want. I had a guy, um, got his own survey company, been on my course. He ran me up one day, he said he was trying to find a, a pumping main, rising main, uh, or in America, a force main.

111:10And I said to him, "Have you got two points of contact on the pipe?" He said, "Yeah, but they're about, um, 600 meters apart." I said, "Well, get yourself about a kilometer of reasonably good quality copper cable. Doesn't have to be very big. But you're not going to get much loss down that cable." So, in this scenario here,

111:34your circuit is down through your pipe and down through your return. And obviously, alternating 8,000 times per second if you're using 8 kHz. But this is the scenario now. You don't get as much loss through the joints. You will still get loss. But let's say our 50 milliamps,

112:03you might find now it's around about 45 milliamps, 40. You get to a midpoint, 35, and then your signal starts going back up again. As far as an AC circuit is concerned, that's pretty much connections at both ends. You might not always get all the way back to your full amount of current because of little bits of loss, but

112:31we'll end up with this scenario where your signal starts to increase as you get towards your next connection point. So, if you imagine this is now a kilometer apart, and you've got 1.2 kilometers of cable, I know it's time-consuming, and this is something a surveyor usually doesn't have a lot of. But if it's something you've got to find, and I did the same thing at GCHQ, um, down in Gloucester, tracing cables.

113:00If it's something that you've just absolutely got to find, this is by far the best way of doing it. You guys might not have tried it because you've probably haven't got the cable. I believe, um, I was told by Pete on the last course, RD stopped making that long cable. I mean, you can go out and get one yourself. I joke with guys on my course that, um, one day I'll start a web shop. I'm going to call it Steve's Surveyor Shop. And all these things you'll be able to find. Um, I've been saying that for about the last 15 years, and it's never happened, so probably won't in the future. But I believe Vivax are now selling a long, um, extension cable.

113:36Most bits of kit come with a 5 or 10-meter extension earth,

114:40And what happens then is your signal is a bit like, is a bit like a Genny signal, an old-fashioned Genny signal, it starts pulsing. And the problem with using two Gennys is you've still got the same amount of loss in both directions. So, this is still, albeit time-consuming, and you do need the cable, a much cheaper way of doing it.

115:03Locatable rod, yeah, you're talking about putting a locatable Cobra-type rod down a non-metallic pipe, I guess, and connecting on both ends. Yeah, that'd work great. The other thing is you can work a lot deeper with these type of techniques because you're not relying on earth. The earth is no longer part of your circuit, it's the cable. So, if you're struggling with things that are deep as well, this will help dramatically in that scenario.

115:32So, that is a double-ended connection, guys. Old-fashioned, tried and trusted technique. The only thing you need is a very long cable. So, look, maybe in the next 15 years, Steve's survey shop, I seriously doubt it'll ever exist, but go to the manufacturers and pester them for one, or just log online and get a long bit of cable on a drum. In this country, you can get empty drums from most hire stroke tool supply companies and just put a load of cable on it.

116:06A thing to say with doing that, this is something I noticed with the RD kit, you do need to uncoil all the cable because the RD kit struggles with the inductance of the cable wrapped up, so you've got to take it all off. It's a bit of a pain. The vLoc transmitter copes a lot better. What happens with the RD kit is you don't get, even though you've got basically as much as you can, a perfect circuit, with the RD kit, you don't get a lot of current. So, you've got to uncoil all the cable. I know that's a pain, but...

116:41Could I potentially make a long cable? Yep, absolutely, Luke. You can stick it on an old toilet roll. It'd have to be a very big one, but any old bit of wood, drum, anything, you can wrap a bit of cable round. So, most of these, in the UK, you can get from the likes of CPC, Toolstation, they sell empty drums and then you can just put your own cable on it.

117:22Uh, extra tracing wire, yeah. Um, what we do on these courses, and it's the same as the survey course, we kind of teach you the purest ways of doing it, and you, it's the sort of thing you don't need to use every single day. You might not use it more than once or twice a year. You guys might, same with CD, you might find that most of your tracing is done fine with 8, 9.8, 33, even higher frequencies.

117:51So, what we're trying to do is give you some pointers on how to, if things are not working out how you want them to, or you're struggling, or you're thinking, "How on earth am I going to find that?" So, any pipe where you've got two valves, a valve and a hydrant, two hydrants, 300-400 meters apart, this technique, obviously assuming it's metal, would work perfectly. You just need a big long cable, and hope people don't trip over it.

118:18Um, we're getting close to 2 hours, guys. We've got some slides to carry on with. It's entirely up to you guys. I'm happy to carry on. We've still got 53 in the room. I'm guessing most of you guys are still awake, hopefully. Um, if you want me to carry on, we'll do a little bit more. If numbers start dropping, or you guys have got to go off and do other things, then we'll wrap it up.

118:46Stick your comments down if you want me to do a few more bits on, we've got some stuff to do on sondes, capacitance. We don't have to do it, it's entirely up to you fellas, but if you're happy to carry on, we'll carry on. If, we, last session we did, we didn't realize, but there was a 2-hour limit on the software and it cut us off, but Pete's now upgraded the software, so if you guys are happy to stay, I'm happy to talk. Um, I have got another session, so I can't talk too long, but...

119:20I'll do a little bit more with you guys, and then we'll, in fact, let me just check because, my apologies, guys, I can't remember when my second session starts. Yeah, it does, it starts at 1:00. So, I'll do about another 10 to 15 minutes, guys, and then I'm doing utility networks at 1:00, so you guys are welcome to hop back in again and join me, or if you shoot off and enjoy the rain in Bristol, or hopefully you've got a bit of better weather, but...

119:49So, this slide you're looking at here, we cover on days 2 and 3 of my surveyor course, doing electrical circuits, so we get guys drawing out electrical circuits, and the good thing about some of them is that they don't always work because the circuits aren't great.

120:14I'm just reading Francisco's comments. Um, I don't know if you, you guys have got contact through Pete, so he would have sent you the, the joining instructions for this, so I guess your best option is to email Pete with your questions and what you want to know a little bit more about, and any comments as well, guys, send them off.

120:37So, you've got your transmitter, which is, in this scenario, your battery, and you've got your red and your black lead, but you've got no connection. So, it's not a completed electrical circuit. So, theoretically, there is no current flow.

120:54Well, this is a technique that's again been around for years. It's never been very well documented by the manufacturers. And it's something that we show people on even a standard CAT and Genny course, just guys out there every day working in the streets using a simple CAT and Genny. The symbol there that you're seeing, hopefully on screen, is the symbol for a capacitor, and that's where you've got two conductors separated by an insulator.

121:22And also, the higher the frequency, logically, the more often it does it. So, you've basically got your red lead, and in this scenario here, that is a satellite or aerial cable running down the wall of a building, plugged in the back of a TV or an aerial satellite receiver box. And underneath the insulation is a conductor. Underneath the red cable is a conductor. So, you've now got two conductors separated by insulators. So, you've now got a capacitor.

122:03Um, Stefan, to answer your question, I think we might be doing one more, but you'll have to, um, keep...

122:25So, as you can see from there, we're using water and earth. For this to work, you do need high frequency, so you're probably 33 kilohertz and above. And what's happening there is the signal is capacitively discharging from the red lead into the satellite or aerial cable, which is then going into the back of a TV or aerial receiver, which is plugged in the mains. So, that's a very simple way of tracing electric supplies.

122:50So, you find a cable on the outside of a building which is going into the building which is plugged into, that could be an outside light, it could be, um, an aerial cable like that. If you're in the middle of a city center, um, there could be an outside light on a building, and you wrap your red lead around that outside light. You've got inside the light, a conductor. You've got the gap between the red lead and the light as an insulator, so you create a capacitor. So, that's what we call capacitive coupling.

123:26And this is again where your high frequencies are very useful. In this country, we've got a lot of cables, BT cables, communication cables running down wooden poles. You can do it anywhere in the world where you've got a cable running down a pole that's got a guard, a shroud around it, so you can't get a clamp around it. The red lead, although you can't see it, up here would be just tied in a knot around there, just so that it hangs down close to the cable. You've got your earth pin in the ground down here somewhere.

124:04And as far as electrical circuit, you need two earths. So, there's one of your earths there. This cable goes off and eventually goes back to a cabinet somewhere. Because in this country, there's a BT cabinet or a comms cabinet, there's an earth there. That's the universal symbol for earth. And there's an earth here. And there's your two earths. And the signal is transferring from the red lead into the BT or comms cable through capacitive coupling.

124:41You may notice when you're looking at your, um, transmitter that you're only getting 2 or 3 milliamps. You don't need more than that. Um, couple of milliamps will suffice at high frequency. And the one thing with all these transmitters, if you press the arrow up button to increase the amount of current, although the bars increase, if you notice the current doesn't increase, then all you're doing is overdriving the transmitter and running your batteries down. It won't damage your transmitter, all it's doing is just eating your batteries.

125:12Another point to make, guys, and I'm sure you know this, pretty much all surveyors do, with any of these transmitters, always, always get rechargeable batteries. I'm not trying to sell the manufacturers, um, more expensive systems, it just saves you a whole load of hassle. With modern rechargeables, you get a lot more capacity than you can get out of alkaline batteries, and you'll find the batteries last a hell of a lot longer when you're on site. And for whatever reason, and none of them, none of the manufacturers seem to be able to tell us this, the battery indicators seem to be a lot more accurate with the rechargeables. If you've ever had the, um, misfortune of using NiCads, if you can remember that far back, NiCads were terrible. But modern lithium-ion or nickel-metal hydride batteries, rechargeables are brilliant, so I would strongly recommend you do that. And you don't need to drive lots of current when you're doing this because the high frequency does it for you.

126:11Pete covered quite a lot of, about peak and null aerials. The only thing to say is if you've got an 8100, I don't know what you guys are using, you've actually got five aerial settings. You really only need peak and null, or peak or null. This is very difficult to explain, and it's not easy to explain when you're actually on site, but that is the aerial, um, configuration for an 8100.

126:45A lot of guys like using peak and null because it shows that on screen. So, you're getting your peak indication using your bar indicator and your signal strength, so your bar indicator, numbers, and your null is indicated by the arrows. The thing you have to be aware of, and I've had a go at RD about this, is that with an 8100, you've got peak plus. When you get used to it, it's very, very good. But initially, if you swap from an 8000 to an 8100 and you press the aerial button, and you go from peak to what you think is peak and null, it might not be peak and null, it might be peak plus, where the arrows are actually mimicking the peak.

127:46So, what you've got to do when you've got an 8100 is make sure if you think you're in peak and null, you are actually in peak and null. And to verify that, when you're in the peak and null setting, so you've got both peak and null indications on screen, you hold down the aerial button for about a second, and in the bottom right-hand side here, it'll say null or guide. Because when it's in null, you then know you're in peak and null mode, and when it's in guide, it's in what they call peak plus mode, where the arrows mimic the peak.

128:24I know this probably, if you're used to it, makes perfect sense, and if you're not, it probably makes no sense at all, but basically, you can be confused by the fact you're getting peak and null in the same place when you're actually not because you're not in peak and null mode. My biggest complaint, and I've had a go at RD about this, is the box shows exactly the same symbol, whether it's in peak plus or peak and null mode. You can change that in the sub-menu, you can go in the sub-menu and change which one it defaults to, but just get used to the fact if you've just changed over from an 8000 to an 8100, you may not be in peak and null mode, you might be in peak plus. Um, guidance mode, which they also have in the peak and null mode just to confuse you even further, is basically MetroTech mode. If you guys have ever used a MetroTech, it's exactly the same display as a MetroTech. They obviously can't call it MetroTech mode, so they call it guidance mode, but it does exactly the same as a MetroTech. It's a center position

129:00Guidance mode, which they also have in the peak and null mode just to confuse you even further, is basically Metrotech mode. If you guys have ever used a Metrotech, it's exactly the same display as a Metrotech. They obviously can't call it Metrotech mode, so they call it guidance mode, but it does exactly the same as a Metrotech. It's a center position needle. If you go left, you get a constant signal, to go right, beeping all the way around, and it behaves exactly the same as a Metrotech. Auto gain. If I were you, I'd switch it off unless you like Metrotech mode and you're in a fairly interference-free area.

129:36Broad peak, I use it all the time for cable fault detection, but if you're not doing cable fault detection, I'd turn it off. It says there, used to detect and trace very weak signals, for example, deep utilities. This was true in the analog days, this is not true in the digital days.

129:56In the old days, the electrolocation kit used to press and hold the depth button and that used to switch it off the bottom aerial and keep it on that, so it went into single aerial mode. On the 8... sorry, 800, you used to be able to switch it into single aerial mode. So, with analog machines, it was very, very good. Unless you guys know different, I've never managed to get it working very well on a digital machine, but it is useful for cable fault detection. So, on my machines, it's usually left switched off, but you guys can switch it off.

130:28Some people prefer to look at the peak and null separately, so it's entirely up to you whether you have peak and null enabled together or you just have peak and then you have null, it's entirely up to you. The one thing that peak didn't explain with a null aerial, I'm going to use this mock-up scenario here. So, this is obviously directional. It can only detect a signal which is coming from this orientation or that way.

130:56But a null aerial is omnidirectional. The signal can be coming from any orientation flowing through the aerial. This is one of the other issues with a null aerial, the fact that it's omnidirectional, it has no direction. The way that you get the arrows on the screen is little sub-aerials either side which indicate the position with the arrows, but as Pete also said, a true null, and this is what a lot of people don't realize because they tend to just look at the arrows, a true null is where the signal response goes to zero and then rises up to a high setting.

131:29So, if you're not getting a true null, it's dropping down from maybe 80% down to 30%, it's not a true null, even though the arrows might seem to be pretty precise. You want to see that signal disappear completely and then rise back up again. But, as I said earlier on, this is all the purest stuff. This is not, you guys probably don't have a lot of time to do this, so.

131:52So, you've got your arrows, you've got the impression of a much greater accuracy, and the response is quicker. If you've got an 8100, you're going to get arrows on peak if you're in the guidance mode. If you've got an 8000, you've just got a single response which rises and then falls, hence the peak terminology. And the variation can be quite sluggish when it's deeper. The other thing is that's also a function of frequency. So, with low frequency, you're going to get a slower response than you are with a higher frequency.

132:34This is a classic example of distortion, and it's predominantly in power mode. In the background there, you can see a car. The power reading is giving me two indications about a foot, 300 mil, either side of the actual position. So, there is actually nothing out there apart from that's where the field is. Directly over the car, nothing.

133:03Signal again. This is not a fault of the machine, this is just where the magnetic fields are. Every machine will give you exactly the same indication. And that is where we were tracing. Two triplex 11kV cables and a low voltage side-by-side in a trench. Indications in the wrong place.

133:32This is one of the downsides of using power. Useful frequency to have, but very commonly nowadays, huge amounts of distortion. A lot of guys are getting this where you're getting readings in the wrong place. The interesting thing about that site is when we used radio and we induced onto those cables, the indications were spot on. So,

134:01Traditionally, we only switch between peak and null to verify depth. And when the peak and null responses weren't in the same position, we didn't bother with depth.

134:19That's probably a much better indication than what I tried to show you, um, holding the vLoc receiver up. So, you can see from the classic response, a red indication. So, if you guys have played around with this, it's very quick and simple. Although that's in null mode, you've got a red response indicating distortion. So, if that was green, you know you've got a good signal, clean indication. Blue, I've found it, it's very, very close to being spot on. The other thing I've noticed with the vLoc, and you guys, if you've switched around between different machines,

135:00and like I said earlier on, I have no allegiance to either company, but friends who work for both manufacturers, um, I would always recommend before anybody shells out the hard-earned cash on this equipment, borrow a bit of kit from either manufacturer and try them both side-by-side. That's always the best way. See which one you prefer. They probably won't like me to say that, but, um, that's the way I do it. Try both machines side-by-side. I do find that the vLoc Pro 3, just that color screen makes it so much quicker to look at distortion levels. So,

135:37Um, we are kind of running out of time, guys, and I need to have a quick break before I start my next session. Most of the manufacturers, certainly, um, the PDL, PXL range of RD kit and the, um, vLoc Pro series will do depth in power and CPS frequencies. If I were you, I'd ignore it. We spent a long time convincing the engineers to take depth off power. In the old days with the analog kit, the depth button just worked. So, you'd press the depth button and it would work in any mode, even though it was useless in power and radio, it did give an indication. So, we managed to get them to take it off in the digital days, and then they put it back on again. So, um, I would strongly recommend that you don't use depth in power. And if you guys have used CPS, um,

136:10So, you could press the depth button and it would work in any mode. Even though it was useless in power and radio, it did give an indication. So, we managed to get them to take it off in the digital days and then they put it back on again. So, um, I would strongly recommend that you don't use depth in power.

136:27And if you guys have used CPS, um, again, we're running out of time, but, um, CPS stands for cathodic protection system. It's basically just a power harmonic. So, its inaccuracies are going to be probably as bad as power inaccuracies.

136:44Every manufacturer sells it as a way of finding high-pressure pipelines, which in the middle of nowhere, it is. But having said that, in the middle of nowhere, a standard CAT would find a high-pressure pipeline in power or radio mode. So, CPS does not work well in congested areas because you'll just pick up power signals.

137:02So, in the UK, that's going to be 100 Hz, and in the US, it's going to be 120 Hz. And in the, um, congested area in the middle of a town center, city center, um, 120 Hz, you're going to pick up, um, power cables. So, active tracing of high-pressure pipelines is always your best option, using a transmitter and low frequency.

137:27And if any of you guys are remotely interested, that's how it calculates depth. So, obviously, the distance between the two aerials inside the machine are fixed, and the depth is proportional to that. So, as it gets deeper, that ratio is going to change. As it gets shallower, obviously, the converse happens. And you've still got to remember the size of your pipe.

137:49Small cable, it doesn't make a massive amount of difference between there and there. Large pipe, obviously, it does. Guys, I'm running out of time. Um, I appreciate you guys have stayed to the end. Still 44 people on there. Um, thanks very much for your attention.

138:08How do you check the distortion in power and radio? Um, in power, you've got to kind of accept the fact that there's always going to be distortion. What you can do, Jeff, is you can put it onto one of the harmonics. Um, so, with the vLoc Pro and the 8100, you can, um, switch to 150, 250.

138:30The machine then acts like it's picking up an active signal. So, you then get peak and null, um, you can get the color display on your vLocs. All you can say is generally expect to find distortion in power and radio. You can't really check in radio. Um, but certainly use the harmonics on the, um, 8100 and the vLoc Pro series machines if you want to see how really badly distorted it is. What I'd normally say is modern cables, it's going to be very badly distorted anyway, so.

139:03Thanks, guys. Any comments, please, um, stick them on, um, the feedback, which I don't know much about, um, because Pete's the expert on this, um. I'm going to have a quick five-minute break, grab a cup of coffee. Um, if you guys are staying for the, um, network session, um, you're a braver man than me, having to put up with me for that length of time. But thank you for, um, your attention.

139:31I think we're going to do one more of these, um, before, um, hopefully, everybody's out of lockdown. And, uh, stay safe, guys, out there.

141:32Oh. Yeah, I had to. I'm running out of time. I need a pee and I need to, um. Yeah, I think so. I ended up with, what, 44 at the end? I think so. And, um, I'm trying to find it.

142:06Right. The other one that says 'is on air'. And I'm still on air, yeah. How do I stop, how do I stop sharing this? Okay.