I have the need to identify which of 100 radios is transmitting on a repeater based system.
At one of our large customer sites they have a problem with individuals transmitting jokes who cannot be identified. They have asked us for a solution which will be able to tell who is transmitting at a given time. The customer put it simply… could we log the serial numbers of who is transmitting at any given time and log those details?
Since they have a TAIT 7100 repeater with 100 channels I had the idea of programming all of the radios with a different TX frequency, while all of them use the same RX frequency. The repeater would then be programmed to RX on all of the different channels and TX on the same channel. Then my idea would be to use something like the Kaltman Creations IW1800 PC Based Spectrum Analyzer, but I do not know if this will record/log timestamped transmissions on an ongoing basis.
Could anyone tell me if this is the right way to go about this or if there is some easier way. The only other thing that I can think of would be to programme the radios with different use DCS/CTCSS tones that could be logged using some special device that I am unaware of… this would be much easier to setup as programming a repeater when each individual handset is added to the system (which is often) could be a can of worms.
Unless you can get the system licensed to use all those channels (and you can’t, the Cypriot version of the FCC would not tolerate this kind of waste), no, you can’t do that.
Most likely, the system already uses CTCSS/DCS, and unless it happens to have no other systems on the same frequencies in the area, you can’t randomly fiddle with those, either.
Some radios do have the ability to transmit the radio’s internal ID number on each transmission, and that would be one way, if your system’s radios have that capability. (MDC1200, probably others)
Otherwise, you may be able to find someone offering a commercial version of Transmitter Fingerprinting, which allows detection of individual transmitters by the varying characteristics of how each one keys up.
Oh, searching around, I find he’s asked this elsewhere, and there mentions that the user involved is using non-type accepted ham radios, so, easy answer… call the Cypriot version of the FCC and have the system shut down. <grin> Most Euro countries are quite firm about that sort of thing.
The radios they have are Alinco DJ-V47 with 39 tones… as per spec
I have found the answer… we need radios with ANI / PTT ID which transmits a serial number at the start of each transmission.
Then we could use a logging system such as the ones provided by Midian Electronics …their “ANI System” appear to be designed exactly for the job and there is a PC based version which has full data logging capabilities.
The only problem is that in my situation our customer would have to replace all of their radios since they dont have PTT ID.
I have just read this thread that I started some time ago and want to clear up the fact the the user has a license for the currently used frequencies. Also, the Alinco V47’s are FCC type approved, contain CE markings and are ROHS compliant.
I dont know why people have the idea this is an illegal system. If I am missing something please let me know what it is so I can do something about it.
If so, you can mandate a policy change to require all users to change equipment to radios that transmit an ANI that you choose.
Also, each user, is required to transmit their call sign at the proper interval. Of course, the jokers would probably omit this… but if thay have a radio with an ANI, then the user could be identified. Each user would have to sign out their particular radio, which could be logged as “so and so”
If your comany does not own the repeater, then you are out of luck.