Log VHF Radio without Identifier

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Log VHF Radio without Identifier

Post by miknwv » Mon Apr 10, 2006 3:12 pm

There have been some recent issues come up about VHF radio abuse in our area. I've been blamed even though I have tons of proof I'm totally innocent, the only reason I was blamed is because I dont' have a DTMF identifier. At any rate, the "powers that be" took my radio away claiming that they have a logger at the dispatch center that can tell what radio was transmitting the wrongdoings even though the radio didn't have an identifier by using an electronic "fingerprint" that each radio leaves behind. This person has a long history of bluffing and a longer history of trying to pin things on me, and I think he is going to claim that this "logger" said it was my radio even though he really has no clue whose transmitted it. My question is....does this type of logger exist?

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Post by Alex » Mon Apr 10, 2006 3:47 pm

From what I understand, there is the ability to "fingerprint" radio waves. However, I don't see this as being something that the average lay person can do.

In order to do this, they would have to probably have some sort of spectrum analysis off the offending interfearence as well as your radio in order to make this comparison. Not knowing more, I would tend to doubt ones ability to do this unless they are a top notch RF engineer - who would notably have better things to do...

Also, if your being accused of something legally, and have the potential for legal action to come upon you for something you did or didn't do (innocent till proven guilty...) don't take advice from a message board. Hire a lawyer.


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Post by miknwv » Mon Apr 10, 2006 3:49 pm

True...I guess I figured there would be some top notch RF engineers hanging out around here before spending money on a lawyer.

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Post by ka7wnf » Fri Apr 14, 2006 7:36 pm

There is software that will log "transmitter fingerprints" It uses a tap off the discriminator of a receiver and feeds into a soundcard. xmit260 is one such program. Years ago a local ham repeater had it set up so it logged everyones fingerprint. Kerchunkers and other abusers soon found out that they could no longer key up up the repeater. So it could very well be true that he logged your fingerprint. pl

http://www.motron.com/cgi-bin/motronsto ... words=txid

look here also.

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Post by miknwv » Mon Apr 17, 2006 8:42 pm

LOL it wasn't my fingerprint he logged. Like I was sayin, it wasn't me that was doin it. I'm just thinkin he's gonna try to pin it on me anyway by claiming the fingerprint came from my radio. I'm 150% positive it wasn't me doin it and it wasn't my radio doin it either. That's not to say that I didn't find out eventually who or what radio was doin it but I'll never tell him.

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Re: Log VHF Radio without Identifier

Post by jim202 » Sat Apr 29, 2006 7:11 am

Unless the person is the FCC with a court order, they have no legal
claim to take your radio away. Many agencies try this move, but
it doesn't stand up to any legal test. Ask to see in writing where
they have the legal ability to take your radio.

As far as the radio finger printing goes, yes the technology does
exist. Problem is that it is not that widely available. If it is bought
off the commercial market, it is very expensive. I can't see any
Public Safety agency spend this kind of money on something that
has such a limited use.

I have also seen this finger print system used in the ham radio
service and be very effective. When there is a person or persons
that constantly cause problems, the individual radios are logged
and use rejected on the repeater. This is a very labor intesive
system as someone has to be able to tell the computer to reject
the signature as it is recorder. If your not at the keyboard when
the transmission is made, how would you tell the system the radio
needs to be rejected?

On the downside of this system, if the person that is being targeted
starts to use different radios, these other radios will also be put on
the reject list with time. If the person borrows a radio from
someone else, this borrowed radio may end up on the reject list.
I have seen it happen where a number of radios that were borrowed
were made unuseable by friendly owners. So be careful who you
loan a radio to.


[quote="miknwv"]At any rate, the "powers that be" took my radio away claiming that they have a logger at the dispatch center that can tell what radio was transmitting the wrongdoings even though the radio didn't have an identifier by using an electronic "fingerprint" that each radio leaves behind. [/quote]

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Post by wa2zdy » Thu Jul 13, 2006 3:35 pm

I know, old post being brought back to life . . .

I'm assuming the original poster had an agency issued radio and that the issuer has decided to take it back. Nothing illegal about that unless it can be construed as some sort of job discrimination. Of course if the radio is the personal property of the original poster, you're right, the agency has no legal authority to seize the radio. (There are of course exceptions, namely if the agency is a law enforcement agency and the radio has been legally seized as evidence of a crime . . . )

Makes me wonder why the powers that be are so intent on accusing the original poster of wrongdoing.

As for the fingerprinting, I've seen it used very effectively. I won't get too far into details, but essentially every oscillator is a few hertz off this way or that and each has its own start-up characteristics, etc.

The most common way we used it was to profile the transmitters being used to cause problems, then waiting until the same transmitter was later used legitimately. The transgressor would then get a phone call or a visit from folks who knew how to promote joy and harmony.
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The human race is proof that Darwin was wrong.

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Post by LarryB » Sun Aug 06, 2006 11:16 am

Yes it looks very much like a spectrum analyzer, make friends with a radio tech and ask what some of that expensive equipment is used for. No radio is perfectly aligned and it really shows, modulation characteristics are different for each radio, and some radios use different methods to acheive this. Has this problem been resolved. If I had an idea who was causing the problem I "would" tell some one who it was. Peoples lives rely on these radios , and sadly most of the interference I have seen comes with an agency supplied identifier. I did not intend to sound radical on this but it is a problem almost everywhere at one time or another. At least they did not threaten you with the "homeland defense" clause that everyone is using when they have nothing else to use. I repeat what has already been said "GET LEGAL COUNCIL".
broke it darn it

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