Philly/South Jersey area Federal frequencies

[ampulman]

I spend a lot of time at my computer w/ at least one scanner tuned to federal frequencies. It seems that for about a week or two (concurrent with my acquisition of a PRO-106, that the frequencies have been quiet by comparison.

Only seem to recall a couple of short (1 - 2 sentences) transmissions in the clear, with little encrypted comms.

There doesn't seem to be any of those (I'll call them data) transmissions; the ones that go: DAH.......DAH......DAH....ad inf., followed by brief pause, then: dah (reply). Anybody know what they are?

Funny thing about them. While holding on an ongoing conversation, sometimes I'll hear one of those ^ interspersed with the voice. It seems that they both could be transmitting at the same time. The voice as P25; the data, with CT/DCS?



Amp

 

[SOFA_KING]

I spend a lot of time at my computer w/ at least one scanner tuned to federal frequencies. It seems that for about a week or two (concurrent with my acquisition of a PRO-106, that the frequencies have been quiet by comparison.

Only seem to recall a couple of short (1 - 2 sentences) transmissions in the clear, with little encrypted comms.

There doesn't seem to be any of those (I'll call them data) transmissions; the ones that go: DAH.......DAH......DAH....ad inf., followed by brief pause, then: dah (reply). Anybody know what they are?

Funny thing about them. While holding on an ongoing conversation, sometimes I'll hear one of those ^ interspersed with the voice. It seems that they both could be transmitting at the same time. The voice as P25; the data, with CT/DCS?



Amp

That DAH...DAH...DAH noise (I really want a filter for that crap) is called OTAR, or Over The Air Rekeying. That is how CBP/ICE/BP/CIS/DEA change the encryption keys in the field radios. If some talks during the download, the system pauses until there is no traffic, then the KMS starts sending again until the final ACK from the target radio confirms the completion. You will not hear P25 OTAR. The data is masked by the vocoder in your radio (thank God for that).

 

[ampulman]

That DAH...DAH...DAH noise (I really want a filter for that crap) is called OTAR, or Over The Air Rekeying. That is how CBP/ICE/BP/CIS/DEA change the encryption keys in the field radios. If some talks during the download, the system pauses until there is no traffic, then the KMS starts sending again until the final ACK from the target radio confirms the completion. You will not hear P25 OTAR. The data is masked by the vocoder in your radio (thank God for that).

Thanks for that information. Are you saying that, if I hear it, it ISN'T P25? Relying on memory, it seemed that most of the active channels were digital, w/ or w/o partial encryption.

Now that I have a PRO-106, I can catch a NAC, but the voice transmissions are few, far between, and brief.

Amp

 

[SOFA_KING]

Yes, not digital. I'm listening to that noise right now. The ICE guy is trying to chase down a van right now and the dispatcher is saying "is your radio in need of a rekey? Because it keeps transmitting." I think they are going overboard on the update cycle...like every day. What a bunch of noise!

Always look for PL or NAC. Analog encryption is not the same as digital or P25. Analog encryption sounds like an open squelch with a high pitched squeel at the end of the transmission. P25 encryption sounds like a Nextel being flushed down a toilet.

 

[Squad10]

That DAH...DAH...DAH noise (I really want a filter for that crap) is called OTAR, or Over The Air Rekeying.

I always wondered if the Midian Electronics BTD-2 MOD 1972 MDC1200 ANI Packet Squelch Module would filter the OTAR (DAH...DAH...DAH noise) signaling packets. Chicago Customs and BATF once used/shared the Customs OTAR channel, both agencies have gone P25 a long time ago.

(Midian) DESCRIPTION
Significantly reduce having to listen to annoying ANI packets. The BTD-2 MOD 1272 is a specially modified BTD-2 designed to squelch ANI signaling packets, in particular MDC-1200® packets. It will also work with many other signaling protocols that have a known single-tone preamble of at least 20 ms. Upon detection of a signaling packet, the unit turns on a transistor for a preprogrammed amount of time. This transistor output can be routed to the squelch circuit of a radio, or be used to clamp the audio to ground.