Batboard

We have been recieving, on a state mutual aid channel 154.2800, a data burst about every min to 1min 30 seconds.

It is thought to be some type of scata or other monitoring device.

It has become a problem and we need to track it down and try and get the owner to change freq's.

Any ideas how to track this down?

Thanks

A vhf yagi on a broom stick, and a spectrum analyzer. Its called fox hunting, I'm sure some of the hams can give you tips on it. I tracked a rogue msf5000 on our merci frequency once with this method, but mine was keying more often than that.

bjlf wrote:We have been recieving, on a state mutual aid channel 154.2800, a data burst about every min to 1min 30 seconds.

It is thought to be some type of scata or other monitoring device.

It has become a problem and we need to track it down and try and get the owner to change freq's.

Any ideas how to track this down?

Thanks

State White 1? Where you located?

Isn't that what you pay the FCC for?

If the FCC are anything like ACMA, they'll want you to do at least some of the legwork to figure out who it is first, before driving out on an expedition for a couple of days to find it themselves.

Have you tried looking at the FCC database for any new license
in your area on the frequency? Just a thought that might
save you some time and effort.

Jim

bjlf wrote:We have been recieving, on a state mutual aid channel 154.2800, a data burst about every min to 1min 30 seconds.

It is thought to be some type of scata or other monitoring device.

It has become a problem and we need to track it down and try and get the owner to change freq's.

Any ideas how to track this down?

Thanks

I highly doubt they are licensed for the transmission. Where are you located. I know that freq is statewide mutual aid in IL and IN is that a national freq? How long are the data bursts?

154.280 is NC state fire and 155.280 is NC state rescue as well.

That is GA and TX Fire mutual aid, as well.

154.280 is supposed to be nationwide mutual aid. does anyone know if it's supposed to be mandatory? half the departments i deal with are still vhf and the other half that have changed to 800, all of their new vehicles don't even have a vhf radio in them. same with pd, the new ones that have gone to 800 don't have a vhf radio in them for ileen.

oh and any way you can post a clip of the sounds you are hearing? most of us can at least tell you what the sound is, once you know what you are looking for it makes it easier to find.

The county I worked for in GA had an 800 talkgroup that patched back to the prime site and cross band transmitted on 154.28. I'm sure that not every agency did that, and it would be of no use if our equipment was out of range from our 800 trunking system, but it was a nice gesture; I thought...

Our 800 system is also patched at the console to 280. Do you guys use 155.340 for hospital call ins? NC law mandates that every ambulance in NC regardless of 800 system or not also have a VHF radio! I would check the FCC database for anything close to you with the freq.

Bruce1807 wrote:Isn't that what you pay the FCC for?

I can't speak for the FCC, but up here in Canada, Industry Canada won't lift a finger unless you can pretty much give them a name and address of who's doing it and have rock solid evidence.

I am in Mirrouri.

I know FCC won't do anything without some documentations, That is why we want to try and find the source.
If we ask nice we should not need to call FCC.

This is a state wide mutual aid freq.

I have looked at some of the Fox Hunt sites and am working on a direction ant to connect to a HT or scanner.

The data burst and key up is just 2 -3 seconds long.
The frequency of occurance is varied from every minute to 3 or 4 minutes.

bjlf wrote:I have looked at some of the Fox Hunt sites and am working on a direction ant to connect to a HT or scanner.

The data burst and key up is just 2 -3 seconds long.
The frequency of occurance is varied from every minute to 3 or 4 minutes.

You are going to want something a little more sensitive than an HT or a scanner, like a nice frequency analyzer...I wouldn't waste my time doing DF with a HT, they are too deaf....plus, you are not going to get accurate and definitive signal strength qualities.

I second that. It'll be an exercise in frustration, otherwise.

thebigphish wrote:

bjlf wrote:I have looked at some of the Fox Hunt sites and am working on a direction ant to connect to a HT or scanner.

The data burst and key up is just 2 -3 seconds long.
The frequency of occurance is varied from every minute to 3 or 4 minutes.

You are going to want something a little more sensitive than an HT or a scanner, like a nice frequency analyzer...I wouldn't waste my time doing DF with a HT, they are too deaf....plus, you are not going to get accurate and definitive signal strength qualities.

You might be suprised, as long as it has a fairly decent signal strength meter you can get it done. I also use an FT-817 with great results, coupled with a homebrew tape measure beam and homemade attenuator.

It helps to know a bit about map reading as well, but I get an initial bearing, then go at a 90 degree angle to it a few miles and get a second, then a few miles more and get a third. Now plot a line from each point in the direction you got on a map.... where they meet, your transmitter resides.

Do you need the atinuator with the ant?

What do you mean by tape measure ant?

bjlf wrote:Do you need the atinuator with the ant?

What do you mean by tape measure ant?

Yes, for best results...

It's a beam made from a tape measure...Cheap, easy, like my last date

But really, it's a lightweight, easy to store portable beam...


http://www.google.com/search?hl=en&q=ta ... re+antenna

BJLF, Where are you located in Missouri? I am in North Central Missouri and i hear the same thing up here on the State Fire Aid also.

Mikey

W4WTF wrote:You might be suprised, as long as it has a fairly decent signal strength meter you can get it done. I also use an FT-817 with great results, coupled with a homebrew tape measure beam and homemade attenuator.

It helps to know a bit about map reading as well, but I get an initial bearing, then go at a 90 degree angle to it a few miles and get a second, then a few miles more and get a third. Now plot a line from each point in the direction you got on a map.... where they meet, your transmitter resides.

I will not be suprised about the unit that you said, as it is a HAM unit, with a decent RSSI setup on it, both of his suggestions were FAR FAR less suitable for his plan...as an HT series has a downright miserable RSSI display, and most scanners don't even offer such!

i'd start my tracking by making some phone calls, call other local departmenst in different directions and see which ones are also hearing it and that will tell you how far it is reaching in each direction then find the center area from there.

I'm in South Central MO and havent heard anything, but could go over to one of our tower sites and dial it up there... Curious to see where the OP is from...

I am in Hannibal.

I will try this weekend to capture and recrd the burst.

Would there be any way of decoding what it is.
I have contacted a local ham and he said he would bring it up at there next meeting.

It seems to happen more frequently in the early afternoon. And like he said it doesn't last but about 2-3 seconds at a time.

The "data" burst could be being generated by two different transmitters signal mixing together. Finding the problem might turn out more difficult than you think. Remember pager transmitters in the vhf band are at least 100 watts, some as high as 500 watts. Mix these signals with even a 1 watt transmitter close in vicinity, and the sum or difference of these two signals could be generating the interfering signal your getting.

I'd use a spectrum analyzer. For one you can see the whole band, and some SA's can receive down to -150 dBm (thats +30 dB better than most scanners or most other two-way gear can rx).

Don't most jammers just dead-key or say crap over the freq rather than take the time to set something up to send a data burst every few minutes?

It might not be MI, but interferience is still bad....

I don't recall the exact details but a law enforcement agency in Southern California was having interference of an almost identical nature about three years ago which eventually was traced to a large construction site which had some kind of surveying instrument on a slight hill which sent out data packets. The instrument was some kind of illegal import without type acceptance, but it was on UHF, unlike this case. There may be something similar on VHF.

Then too, consider a possible volunteer fireman or a paid staffer who wants their own radio to keep track of calls. The databurst signal could be one of those man-down types that has been activated and just happens to dump out on mutual aid or whatever channel has been selected at the moment.

That's the same frequency, for those interested, as used in the Maryland, DC, Pennsylvania, Virginia area too.

Friend of mine, years ago, had a ham transceiver, a Standard SRC-145, that transmitted a spur on the same frequency whenever he would key on the local repeater. Mixing product we thought, since he was nearby the local county RECEIVE site for that frequency.

Nope, it was dirt from the transmitter, that the receive site correctly picked up.

Paul/VJB

WA3VJB wrote:The databurst signal could be one of those man-down types that has been activated and just happens to dump out on mutual aid or whatever channel has been selected at the moment.

Especially since 154.28 is usually simplex, I don't think anyone sane would try to run a rogue data network on that frequency. (I really doubt it's malicious interference of any sort.)

Decoding it might give you some information, especially since it's digital: maybe there's identifying information in it.

That's the same frequency, for those interested, as used in the Maryland, DC, Pennsylvania, Virginia area too.

And New Hampshire. I'm pretty sure it's nationwide.

Getting a ham club involved (as you mention looking into) could serve you well. I've always wanted to go on a foxhunt; if the local FD came to my club and asked for our assistance, I'd love to join in the hunt.

Keep us posted!

Believe it or not you may want to try checking with some of the local government agencies. We had a dealer in our area who for testing puposes installed a data netrwork for the state police on the national PD channel 155.475. It was there for about 3 years before somewone complained and they removed it.

If I can get this recorded, How would I get it decoded?

Thanks

bjlf wrote:If I can get this recorded, How would I get it decoded?

It depends on the format. If you can't identify it, you might be best off posting it (or a link to it) here to help identify it.

I could be somebodys fire department using the new motorola fire ground system. It sends data bursts to the mobile radio in the commanders car. I only think theirs 2 fire departments in the states actually using it. One is in IL.