Fed Encryption

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relicwr

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It's P25. Go do a manual scan and go around the licensee's frequencies and you'll hear it. Is this on a trunked or just a conventional P25 repeater?
 

mike_s104

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Conventional. On that freq., I have heard both P25 and analog traffic in the clear in the past. Also, its different from the other analog (analog signal) encryption I've heard on that freq. Tomorrow if I have time, I will try to dig up on older recording of the encryption sample. So far I have nothing more in length then I posted with that encryption.
 

SOFA_KING

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I have never heard that type of data from P25. I have heard a full time data channel on the USCG, and seen the NAC to confirm it being P25, and it sounds nothing like that at all.

My guess??? Telemetry of some sort...maybe for remote alarming. The FBI used to have all sorts of stuff like that in the old days, but slower data rates.

What scanner was used?
 

mike_s104

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I have never heard that type of data from P25. I have heard a full time data channel on the USCG, and seen the NAC to confirm it being P25, and it sounds nothing like that at all.

My guess??? Telemetry of some sort...maybe for remote alarming. The FBI used to have all sorts of stuff like that in the old days, but slower data rates.

What scanner was used?
Using a 396XT. It sounded like analog, so I set it to analog only and search for a tone...no CTCSS. Like I've said before, I'd heard both P25 and analog traffic in the past on the same freq.
 

Squad10

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From the transmitter's hang time at the end of your recording it seems to me that 167.4375 is a repeater output. So what is heard maybe getting in through the repeater's input frequency. If you know the input freq. you may want to monitor it. It's strange that no CTCSS is being encoded, in all the FBI repeater interefence cases I've heard, either the 167.9 or EOM tones were present.
 

ecps92

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I'm thinking Intermod

From the transmitter's hang time at the end of your recording it seems to me that 167.4375 is a repeater output. So what is heard maybe getting in through the repeater's input frequency. If you know the input freq. you may want to monitor it. It's strange that no CTCSS is being encoded, in all the FBI repeater interefence cases I've heard, either the 167.9 or EOM tones were present.
 

SOFA_KING

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But if it is getting into the repeater, it needs a PL of 167.9. And if it is coming from the repeater, he should see the 167.9 PL on the scanner.

I say it is either on frequency data (not common, but I have heard the FBI do it), or an image on his scanner.
 

ecps92

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So many variables, to make many assumptions.

Could be a Dual Mode Rptr [P25 and Analog]
Maybe someone left the PL of the RX side [happens routinely]

But if it is getting into the repeater, it needs a PL of 167.9. And if it is coming from the repeater, he should see the 167.9 PL on the scanner.

I say it is either on frequency data (not common, but I have heard the FBI do it), or an image on his scanner.
 

Squad10

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It could be intended data on a frequency12.5kHz either side of the repeater input resulting from poor or no frequency coordination.

This happened for years on an FBI repeater input of 165.9000 analog, ATF's channel 5 simplex 165.9125 analog CSQ would often interfere causing the three associated FBI repeater outputs to transmit semi intelligent voice with 167.9.

Anybody know the 167.4375 repeater input frequency?

Wondering if it might be FAA telemetry data audio.
 

mike_s104

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Again, in the past, I have heard P25 in-the-clear and encrypted traffic as well as analog in-the-clear and I believe encrypted (it sounds almost like static except for the squelch tail like in this sample). It is a repeater output.
 
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It could be intended data on a frequency12.5kHz either side of the repeater input resulting from poor or no frequency coordination.

This happened for years on an FBI repeater input of 165.9000 analog, ATF's channel 5 simplex 165.9125 analog CSQ would often interfere causing the three associated FBI repeater outputs to transmit semi intelligent voice with 167.9.

Anybody know the 167.4375 repeater input frequency?

Wondering if it might be FAA telemetry data audio.
telemetry,you mean this sort of deal-e-o..

http://www.philly.com/inquirer/busi..._new_satellite-surveillance_radio_system.html

the newly online sat system for aircraft?
 

n0nhj

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Could also be OTAR data.
(Over the air re-keying) Changing the encryption key on a radio.

They would send it without PL so the users wouldn't hear it.

Chuck
 

poltergeisty

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brandon

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I used to hear something similar (although not quite the same) on a US Customs frequency in San Diego back in the analog days. Not P25, Not OTAR, just some kind of digital noise and showed up with the 100.0 PL. Wish I had a recording of it still.

Speaking of federal encryption... this is my favorite type :D
 
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