Key up signature ?
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Key up signature ?
I have a repeater that is getting a very brief keying several times a day. It is a PL receiver and sometimes I can hear the signal on monitor receiver on input frequency. Because of the random nature and number of times keyed, I am thinking there might be a defective radio. I have heard of transmitter key up signatures. Is this software still available and does it work? Do you have any other ideas on finding a signal that is too quick to hunt?
"The world runs on radio."
Re: Key up signature ?
You need a very good receiver to do transmitter fingerprinting. You are measuring the instability of the transmitter's oscillators, and how they vary in frequency when they come up, so you need a very good receiver, preferably DC coupled so that the receiver isn't introducing any variables, that is wide enough bandwidth to capture the transmitter's wanderings in those milliseconds of keying up. The detector on the receiver has to be fairly wide bandwidth as well - you want to be able to get tens of kilohertz of demod bandwidth (normal radios are only about 5kHz at best, usually less than 3kHz).
And when all is said and done, you STILL need to be able to have a suspect radio to compare against the fingerprint - this is real life, not CSI: Crummy Science for Idiots; you cannot plug the waveform into a magical comparison machine and out pops a suspect.
One thing you might try is a directional antenna at the site. Pick a direction, put a monitor receiver on it, set the squelch to be just a scosh tighter than your repeater's squelch, and see if it breaks squelch when the event happens. Move the antenna a bit and try again. You may be able to get a bearing after a bit.
And when all is said and done, you STILL need to be able to have a suspect radio to compare against the fingerprint - this is real life, not CSI: Crummy Science for Idiots; you cannot plug the waveform into a magical comparison machine and out pops a suspect.
One thing you might try is a directional antenna at the site. Pick a direction, put a monitor receiver on it, set the squelch to be just a scosh tighter than your repeater's squelch, and see if it breaks squelch when the event happens. Move the antenna a bit and try again. You may be able to get a bearing after a bit.
This is my opinion, not Aeroflex's.
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I AM NOT the Service department: You want official info, manuals, service info, parts, calibration, etc., contact Aeroflex directly, please.
I WILL NOT give you proprietary information. I make too much money to jeopardize my job.
I AM NOT the Service department: You want official info, manuals, service info, parts, calibration, etc., contact Aeroflex directly, please.
Re: Key up signature ?
Hello:
You didnt say what freq band it was on but for some info input ill add this below:
I have a CSI 32 comunity repeater tone panel rigged up for GM300 mobiles.
It has the ability to count / display / repeat / DPL or PL tones.
You can disable repeat and actualy count the key up number of any DPL or PL .
By putting it in line or adding another antenae you can at least verify the PL in qestion by the count of key ups.
There was at one time two CSI compnanies and the one that made the CSI 22 / CSI 32 / CSI 32 Plus repeater tone panels has sice gone under and was located in Seattle Washington back in 1987 on Harrison Street.
I have several 32 and 32 plus panels i still use and think quite highly of for there abilities and operational dependability.
If there are any old timers such as myself that remember these panels you more than likely remember the troubles with
PL and DPL decode falseing ect.
I was one of the several companies selected for the BETA tests being done to solve the panels troubles when they first came out.
And ill admit they had there troubles then.
Since i and with the help of the CSI techs and others in the BETA testing did get it solved and it works very well now.
But the tone panel didnt catch enough attention and the compnay went under.
I still have the eproms and chips that i can burn on a eprom burner to duplicate to maintain the 32 and 32 plus panels yet today.
Whats neat about the 32 panels is that the owner can from a mobile or at the site manualy add or delete any PL / DPL tones even non standard PLs and as long as its not closer tha 2.5 hz of another standard pl it WILL work perfectly if setup corectly.
Yes they were that good and mine will do that as well.
Id consider getting something of this type of setup ( Not necesarialy a CSI32 ) if you were really in the need to know what tone it was.
satelite
You didnt say what freq band it was on but for some info input ill add this below:
I have a CSI 32 comunity repeater tone panel rigged up for GM300 mobiles.
It has the ability to count / display / repeat / DPL or PL tones.
You can disable repeat and actualy count the key up number of any DPL or PL .
By putting it in line or adding another antenae you can at least verify the PL in qestion by the count of key ups.
There was at one time two CSI compnanies and the one that made the CSI 22 / CSI 32 / CSI 32 Plus repeater tone panels has sice gone under and was located in Seattle Washington back in 1987 on Harrison Street.
I have several 32 and 32 plus panels i still use and think quite highly of for there abilities and operational dependability.
If there are any old timers such as myself that remember these panels you more than likely remember the troubles with
PL and DPL decode falseing ect.
I was one of the several companies selected for the BETA tests being done to solve the panels troubles when they first came out.
And ill admit they had there troubles then.
Since i and with the help of the CSI techs and others in the BETA testing did get it solved and it works very well now.
But the tone panel didnt catch enough attention and the compnay went under.
I still have the eproms and chips that i can burn on a eprom burner to duplicate to maintain the 32 and 32 plus panels yet today.
Whats neat about the 32 panels is that the owner can from a mobile or at the site manualy add or delete any PL / DPL tones even non standard PLs and as long as its not closer tha 2.5 hz of another standard pl it WILL work perfectly if setup corectly.
Yes they were that good and mine will do that as well.
Id consider getting something of this type of setup ( Not necesarialy a CSI32 ) if you were really in the need to know what tone it was.
satelite
Re: Key up signature ?
Zetron M38's do that too. That is what we use.
Re: Key up signature ?
Why not use an RDF and go to the source?
Re: Key up signature ?
It is a single user with one PL and over one hundred programmed units. A quick key up blip is too fast to zero in on. A user with a CDM1250 came by yesterday and thought it might be his unit. We changed mics and are waiting to see if the keyups happen again. The problem radio could be a moving unit or a HT in a charger at someone's house or office.
"The world runs on radio."
Re: Key up signature ?
Realy? The blip is shorter than 50ms? A good commercial Doppler DF can lock on ANYTHING at 50ms.
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Tom in D.C.
- Posts: 3859
- Joined: Tue Sep 04, 2001 4:00 pm
- What radios do you own?: Progreso soup can with CRT
Re: Key up signature ?
Or, take a political approach and announce to the users that you're about to put a "radio identifier" into use to
see who is kerchunking the system. If it's one of the guys doing it you should notice an immediate change or,
hopefully, cessation of the problem. If it keeps up the same way you'll know it's not a people problem. Just a
thought. Assuming that the users are not radio techies this might just work.
see who is kerchunking the system. If it's one of the guys doing it you should notice an immediate change or,
hopefully, cessation of the problem. If it keeps up the same way you'll know it's not a people problem. Just a
thought. Assuming that the users are not radio techies this might just work.
Tom in D.C.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.