What type of signal?

**nop's** · October 20th, 2009, 09:17 PM

What Type Of Signal Are You Using When You Use Induction To Locate An Underground Utility? What Type When You Direct Connect?

**Mke** · October 21st, 2009, 09:07 AM

you mean frequency?

What type of Equipment you using?

My 810 is a set frequency so the two signals would be the same, and if memory serves me right its right about the 83.0775kHz area.

Other equipment may have a range of frequencies, and your question could be answered better by someone who's more familiar with that piece of equipment

or something like that.

mke

**BabyGirl** · October 21st, 2009, 06:23 PM

Not quite understanding what you are asking.... The signal on both Conductive and inductive very on what equiptment you are using, what utility you are trying to locate, and how congested the area is (with other utilities).
What equiptment do you use?

**FiosKing** · October 21st, 2009, 08:16 PM

i use 65 ... my personal fav

**ifinditunderground** · October 21st, 2009, 08:48 PM

Originally Posted by nop's

What Type Of Signal Are You Using When You Use Induction To Locate An Underground Utility? What Type When You Direct Connect?

Someone here can answer your question if you clarify what question you need answered.

**yahoo** · October 21st, 2009, 10:16 PM

mostly.........i use 29khz for both locates!!!!

**Dave72** · October 22nd, 2009, 12:01 AM

Originally Posted by nop's

What Type Of Signal Are You Using When You Use Induction To Locate An Underground Utility? What Type When You Direct Connect?

Ill take a shot at it too..

By "type" of signal.. are you curious as to how the signal gets there (as in "what type of signal am I using when I...") ?

When you 'drop' the box or use the inductive clamp, you are creating an EM/RF field. This field will generate a/c current flow on anything conductive (either within the field in a 'drop', or directly onto whatever you're clamped to). This a/c flow will in-turn generate its own em/rf field in the conductor.. which is what we detect with the receiver wand.

Direct connection is much the same, the a/c signal is applied directly to the conductor.. it's a 'more pure' way of doing it.. less chance of error.

**sprayandpray** · October 23rd, 2009, 11:05 PM

That question got me to thinking - Are we 'broadcasting' a signal similar to AM or FM or is it more akin to a CB or Short wave transmission?

**Goldenboy** · November 6th, 2009, 06:28 PM

You are still using a radio frequency the same as you would if you have a direct connect hook up. The only difference is you are using different principle to get that signal onto the target line.

Here is a good "training manual" that explains alot about using induction.

Rigid Training Manual

**[HAF]Foxtrot** · December 7th, 2009, 06:56 PM

Its all sent via Radio Frequency. That is the part of the wave spectrum used for utility locating. I keep mine on 8 KhZ, even when inducing. Only difference is when you induce via Pipehorn, Metrotech, Ect. The KhZ frequency is alot higher then direct connect. Most people that direct connect use 8 or 33 KhZ, along with some that use 66 KhZ or 512 Hz (Based off the RD). Direct connecting or inducing with pipehorn for instance would yield you a far higher KhZ signal.

**RD_Wrangler** · December 7th, 2009, 07:24 PM

Originally Posted by [HAF]Foxtrot

Its all sent via Radio Frequency. That is the part of the wave spectrum used for utility locating. I keep mine on 8 KhZ, even when inducing. Only difference is when you induce via Pipehorn, Metrotech, Ect. The KhZ frequency is alot higher then direct connect. Most people that direct connect use 8 or 33 KhZ, along with some that use 66 KhZ or 512 Hz (Based off the RD). Direct connecting or inducing with pipehorn for instance would yield you a far higher KhZ signal.

*blink* ... *sigh*...

**Dave72** · December 7th, 2009, 11:58 PM

AM/Fm, CB, Shortwave, Direct Connect, Clamp, Dropped.. its all just fields.

AM radio has a center freq, the music/voice modulates the power (the A for Amplitude) of the signal, and an AM radio is made to demodulate it. FM has a center freq, but the music/voice modulates the signal freq instead of its strength.. same sorta idea tho. CB and Shortwave are AM class signals (but in different freq ranges.. and then some tricks like sidebands etc).

Locating puts a center freq , but no modulation, onto some conductive thing. With direct connection, the transmission antenna is the thing you hook up to.. with clamp or drop, you're making a field that in turn makes a field on the conductive thing.

The receiver is just an antenna, tuned to the freq signal that you're transmitting (peak and null are just methods of finding the centerline of the conductor when field distortions are of issue)

So, to Spray's question, yes.. we're broadcasting.. low power, crappy antenna design, and no actual 'information' in the broadcast. If someone in the area had a sensitive radio/antenna system, and were tuned to 33khz for some reason .. and you dropped the box, their radio would spark to life with a signal indicator, but there would be no voice/music/etc.

**TMO** · March 21st, 2010, 08:56 AM

Originally Posted by Dave72

AM/Fm, CB, Shortwave, Direct Connect, Clamp, Dropped.. its all just fields.

AM radio has a center freq, the music/voice modulates the power (the A for Amplitude) of the signal, and an AM radio is made to demodulate it. FM has a center freq, but the music/voice modulates the signal freq instead of its strength.. same sorta idea tho. CB and Shortwave are AM class signals (but in different freq ranges.. and then some tricks like sidebands etc).

Locating puts a center freq , but no modulation, onto some conductive thing. With direct connection, the transmission antenna is the thing you hook up to.. with clamp or drop, you're making a field that in turn makes a field on the conductive thing.

The receiver is just an antenna, tuned to the freq signal that you're transmitting (peak and null are just methods of finding the centerline of the conductor when field distortions are of issue)

So, to Spray's question, yes.. we're broadcasting.. low power, crappy antenna design, and no actual 'information' in the broadcast. If someone in the area had a sensitive radio/antenna system, and were tuned to 33khz for some reason .. and you dropped the box, their radio would spark to life with a signal indicator, but there would be no voice/music/etc.

Good answer. Looks like someone is using more than the standard 13% brainpower!lol!

**1idejim** · March 31st, 2010, 01:15 AM

this comes at a good time, i'm giving a class this summer for a group of irrigation tech's that have very little background in locating valves. most of the tech's won't have used multimeters much less locators.

i'll be giving the class using irrigation valve and wire locators designed for these purpose's.

in order to quickly explain how locators work i was intending to use the radio scenario.

the radio station transmits music that travels up an antenna, the music travels through the air untill a radio is tuned to the station and you then hear the music.......

the transmitter is the radio station, the wire in the ground is the antenna and the receiver is the radio.

does this sound like a good low entry level explaination of how locators work?

**Dave72** · March 31st, 2010, 07:21 AM

I think it would be close enough maybe, Jim .
Might need something to show how you could accidentally tune to the wrong station (but based on antenna instead of frequency)..

Like, you have the transmitter, then a bunch of antennas in some antenna farm (ie, the underground pipes, lines, etc).. and you're trying to
use your radio to determine which of the antennas in the farm is being used.