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Thread: Sweeping

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    Banned advanceMan's Avatar
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    Default Sweeping

    Can anyone explain the process and theory behind sweeping/scanning or the three way pass system?( I got dissed by the rottie when I said most of you are one call, but you are aren't you)

    Does anyoneknow how to get PROPER depths through inductive location?

    Can anyone explain telephone routing systems?

    C'mon smart guys, save the dissing and let's hear it.

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    Default Re: Sweeping

    Hmmmm.....Sweeping.....Inductive Locates.....Wonder what would be the best instrument for that

    Chime in gang!

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    Senior Member headcipher's Avatar
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    Default Re: Sweeping

    Quote Originally Posted by advanceMan View Post
    Can anyone explain the process and theory behind sweeping/scanning or the three way pass system?( I got dissed by the rottie when I said most of you are one call, but you are aren't you)

    Does anyoneknow how to get PROPER depths through inductive location?

    Can anyone explain telephone routing systems?

    C'mon smart guys, save the dissing and let's hear it.
    Induction is tricky at first, I have to say.

    As for depth, it all depends on your scope, and if you know the 45 degree rule. But depending on how distorted your signal is that can be off too.

    At my company we use the term "hinging" for setting the transmitter on it's side. It's called that because on the old 810 that's the hinge side.

    But here's how I do it most of the time:

    If I don't know what's out there I put my transmitter on it's side(hinging) pointing out into the target area. Depending on how many facilities are there, how close they are to each other, and what they're made of I may get a few signals. Then I sit my box right on each signal see where they go, while checking each point where the signal steps down for T's. If 2 facilities are too close I might off set the box, or Hinge the box to either side of the signal I'm most sure of.

    Usually using lots of practice and trying different placements of the transmitter, you can find even more than you were looking for.

    Type of locator, experience, and material all play a major role.

    I use a 810 for most of my inductive locates. The Vivax, Rd, and Ridgid can all induce well.

    Hope to try a pipehorn some day though.

    Pipehorns web-site has very useful techniques that work with most locators check it out.

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    Senior Member yahoo's Avatar
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    Default Re: Sweeping

    there is nothing more important in this industry......sweeping...in the end this technique will save you or break you for lack thereof!!! i'm probably off key here on his subject.if so ....sorry
    wise men talk because they have something to say and fools because they have to say something....plato

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    Senior Member GPGrasshopper's Avatar
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    Default Re: Sweeping

    I wanna try...

    Accurately calculating depth while inducing can be done a couple of different ways. First, pinpoint the peak signal reading (Peak A), then position the receiver in a 45 degree angle and move the receiver away from the line until you get a second peak (Peak B), and the distance between the two is the depth.
    You could also try pinpointing peak signal and set the receiver on the ground. Adjust gain to 50% and then lift the receiver off the ground until the meter reads 0. The distance is depth.
    If you are lucky, and your locator is calibrated well, and the stars are aligned, and soil conditions are good, and you found a four leaf clover, and you crap horseshoes and rabbit's feet, the depth button on the device might do it.
    The depth of an induced siganl can also be found by using a pair of evenly spaced orthogonal induction antennas. You measure the signal you are inducing onto the line (one reading from each antenna), and then measure the signal that radiates from the target (one reading from each antenna). The four resulting signal amplitude readings can be used to triangulate the depth.
    Or, you could use a high power, multiple frequency combination of inductive coplanar transmitting and receiving coils with electromagnetic responses of 400Hz, 1500Hz, 6400Hz, 25kHz, 100kHz, and a coaxial coil pair running at 3300Hz if you want survey quality results.
    I have always just potholed the lines and verified it if I wasn’t sure, and then used a tape measure, but there is always an option.

    Telephone routing systems (I am guessing you are talking about the mobile ones) is really just a system that the telephone service provider uses to make routing more efficient. Say you get hammered with your budies, and have to get a cab home. You call the cab service and they have a system for dispatch that uses a technique called Time Of Arrival that goes out and finds all of the cabbies working and calculates how lonng it takes for a signal to reach that mobile asset from three known base stations. It will return and can route the dispatch information to the closest mobile asset. Of course, lately this is all been switched over to GPS based systems but the concept works the same.

    As for the sweeping, are you talking about conductive, inductive, and passive? I am not sure what mean.
    I seek not to know the answers, but to understand the questions.

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    Senior Member headcipher's Avatar
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    Default Re: Sweeping

    Quote Originally Posted by GPGrasshopper View Post
    If you are lucky, and your locator is calibrated well, and the stars are aligned, and soil conditions are good, and you found a four leaf clover, and you crap horseshoes and rabbit's feet, the depth button on the device might do it.
    LOL

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    Banned advanceMan's Avatar
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    Default Re: Sweeping

    Good stuff, keep it up, GP, maybe i should have said pedestal routing/numbering systems ie: a-16 Ther's really a simpler way to explain explain getting good depths, soon. Yahoo, not at all. You obviously know something of it. Three way pass inductive scanning, surely ther's some of those guys here.

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    Banned advanceMan's Avatar
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    Default Re: Sweeping

    Just noticed something on your post cipher, I've never heard of Vivax. I also noticed no ones ever mentioned Fuji's

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    Senior Member headcipher's Avatar
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    Default Re: Sweeping

    Quote Originally Posted by advanceMan View Post
    Just noticed something on your post cipher, I've never heard of Vivax. I also noticed no ones ever mentioned Fuji's
    While I'm waiting on a meet I'll trade ya. Never heard of Fuji locators. Hook me up with the site or full name.

    Here's the link to vivax vlocpro, made by the same engineers as the rd4000.

    http://www.vivax.biz/new/product/vlocpro.htm

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    Senior Member GPGrasshopper's Avatar
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    Default Re: Sweeping

    Quote Originally Posted by advanceMan View Post
    Good stuff, keep it up, GP, maybe i should have said pedestal routing/numbering systems ie: a-16 Ther's really a simpler way to explain explain getting good depths, soon. Yahoo, not at all. You obviously know something of it. Three way pass inductive scanning, surely ther's some of those guys here.
    OK, Let's revisit the ped numbering system. It really does vary form one phone company to another. Nowadays, some of them are have transitioned to a GPS pedestal numbering system.
    Most of the existing infrastructure out there uses a route/lead numbering systems based out of the old C/O systems. The style of route/lead numbering had resulted in mass confusion, as the telcos added new C/O and made various routing changes over the years. Unfortunately, most telco companies have changes several time over the years and now have a couple of different systems in the same infrastructure and opted not to restencil because it was cost and labor intensive.
    The "A-1234. B-5678" is from the route/lead systems. Some companies then switched to a R-1234MS/F-1234MS (Rear of address 1234 Main Street/ Front of 1234 Main Street) way of numbering and are now again switching to a GPS or fixed location numbering system.
    It really depends on the telco company and what system they are using in your area.

    I have never used a three way inductive sweep, so I can't comment to that.
    I seek not to know the answers, but to understand the questions.

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    Banned advanceMan's Avatar
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    Default Re: Sweeping

    Sorry I took a bit to get back, I was at the SLAYER/Megadeth show Friday. It fukin' rocked!



    http://www.detectionsolutions.com.au...e-locators.php

    try that one cipher, I googled it. I don't have much knowledge of them either, I think i used one once. They are supposed to be really good for deep induction so they are popular in the pipeline community.

    Though all your answers were scientific, the farther back you transmitter from the point you want to locate, the more accurate your depths within 6".
    We used this method on the crew many times, then I would see the line hydrovacced, I was right 9 out of 10 times
    For instance, we need to cross a line in the ditch, find the pipe in the field(find it accurately), move you transmitter back far enough from where they went under the road. Set on 65/75%(on the rd 433, comparable settings wil work on other locators.) Good 50 m sometimes. Go to the ditch, locate one point at roadside, one at fence side, one in the middle at bottom, fill in your space, make sure the line is straight(Locating stuff at a raod crossing as you know can be difficult due to the change in depth, I see so many crooked locates at those points from 'experienced" locators) You basically have to be farther from your transmitter than the field it is emanating so that the signal is uncorrupted by the machines power setting. Try it. I have no real use for induction these days.

    Three way pass. this takes two people.
    An easy for insatnce.
    You have two lease sites within a mile of eachother. There is a new pipeline being built between the two All the actual locating has been done and you are there to safety sweep for anything that has been missed.
    One guy holds the box, the other the wand. They stand directly accross the are to bescanned within 30 m of eachother. They walk together from one site to the next down the r/w . When they get to thet other site, they turn back in the direction they just came. This time one guy walks farther ahead of the other so that any utilities coming in at an angle wil be caught. When they reach the first lease site again, they turn around again, and whover was forward remains back, and whoever was bak is now forward and they walk walk the r/w again accounting for angles in the oposite direction. If you left your truck at one site, you gotta walk that last mile. So one mile of scaning turns into 4. When you have finished sacnning the r/w horizontally, then you start the thre way vertically down the r/w. Once the r/w is done, then you scan the lease site and perimeter in the same fashion. This work is all in how you look at it. esentially it's just walking, but to me it's SO tedious and boring. Thse guys generally are paid well, and some of them are very god locators, but I wouldn't do it again.

    You're right about ped routing GP, I'll explain what I know later, no more time.

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    Default Re: Sweeping

    I should also mention that once the r/w has been scanned in this fashion, then the lease site perimeter must also be scanned this way. Some will go even as afr as to employ the circular radius for extra protection by having the transmitter guy stand at the well head or what have you at the centre of the lease, then turn a circle sweep around it. I REALLY hate tht shit, but I have to admit it is the most effective way to scan an unknown area thoroughly. I would use the same method with my helper on the crew except not quite as meticulous for obvious reasons when looking for pipelines. Another thing, your transmitter does not have to be on high as a rule, however many of the lines we need to locate were in excess of 9' some times deeper at road crossings so a high frequency was most effective, and usually starting at 6. I was always told by the foreman if it reads over 12 feet your probably off or don't believe it. Thats why pinpointing it accurately on initial induction is important, if you believe your depth, check it incrementally by foot to depth at the middle, find the drill pit first from regular depth, then check both sides till you come to the middle. When you scan for the pipe, walk parrallel to your partner acrosss the area to be located(ie: facing north, walk horizontally across the vertical pipe with the transmitter furthest in the field, wand closest to fenceline), when you reach your peak, stop, have transmitter stay put, find peak again, tell transmitter to go either direction to peak, stop, check peak again, proceed til u have your highest peak, flag, now test by placing transmitter where wand was(reverse-mark first), fine tune til u have certain location, place transmitter back in fileld (flagged), locate from top of road , line up with flag in field, locate at fence , locate centre of ditch, fill in if you like, check depth, should be level in field and descend towards road xing at property. deepest in midle of road, best depth should be at ditch bottom. Pipeline locators always locate both side even if you don't need it. Even so, I've seen many a crroked line from "seasoned" locators.

    On that depth note, different companies do things....differently. The old crew set a standard by the phone company, my present company, they just hack it in whatever ways cheapest, we would always go around culverst, these guys go right underneath them, and many a time my depth has read on direct connect 25'. Since as long as whoever is digging over it doesn't find it within so many feet of their own depth, it may or may not be true. Kind of stupid, but quite possible. Cunt to dig up, but it's ONLY fibre. In the event a fibre cable is hit, they can move the ISP onto another fibre in a tube that hasn't been damaged briefly if possible this will happen, but in most cases a newline will be run.

    Okay, incidently, haven't done any locates first call in a month. Ben doing fibre overbuild design for a cable company.("assistant design engineering"lol) I think my companies jumping the gun on this one a little, but whatever. First time using a Trimble Recon...piece of shit. We didn't do that girly GPS stuff on the crew . Had to locate a ped out, was already first called for some cable guys doing some residential. Was nicely marked and colourful, all in the right place from what I could see. Gas power phone cable. I saw two orange line heading towards the mall together, and the rest of the ped semingly locate correctly(joint tv tel) After I disconected all the grounds from the bar, the first tel cable in a 4" I located on low frequency was at leaste one metre off. Everything looked so correct and colourful, anyone would have been fooled. If those guys had been diigging on the other side the mall would have been knockedout..maybe.What did that lazy ass (probably 4-6yr)locator do?

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    Senior Member Dave72's Avatar
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    Default Re: Sweeping

    a meter off ? thats a ways.. Was there something running parallel to it ? I wonder if he was locating in null mode. Some of our occasional guys locate in null and it drives me nuts. They like to hear the signal get stronger then fade out.. I dont get how thats easier that just listening for the peak.
    Remember.. always paint in peak. Use null just to verify (and if null and peak agree.. then your depth reading is correct).
    (May you live in interesting times)

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    Senior Member headcipher's Avatar
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    Default Re: Sweeping

    Quote Originally Posted by Dave72 View Post
    a meter off ? thats a ways.. Was there something running parallel to it ? I wonder if he was locating in null mode. Some of our occasional guys locate in null and it drives me nuts. They like to hear the signal get stronger then fade out.. I dont get how thats easier that just listening for the peak.
    Remember.. always paint in peak. Use null just to verify (and if null and peak agree.. then your depth reading is correct).
    He was probably assuming the 2 lines were together, or didn't bother to try seperating them.

    I see similar things all the time. Just yesterday the cable/telco locator marked, on the same job, the high pressure gas main as a fiber and a 34.5 kv electric as a 900 pair.

    Only thing I can figure is he was trying to powermode it. The high pressure gas was rectified and carries a signal of 120hz.

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    Mke
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    Default Re: Sweeping

    I got one for you. I was checking on the one-call locates for a job at a Marine terminal and the City locator marked the 18'' Force main about 2 feet off. This would of been fine, but for the fact that there was an asphalt patch right over the Force Main and his paint was just out side of the Patch.

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