San Francisco APCO25 issues

[rustyhodge]

I just got a Uniden 996XT and loaded the San Francisco Police Department from Radio Reference. For the most part, it works fine. However, the scanner tends to stop for long periods of time on channels that have carrier but no audio. (Well, it does seem like there is a digital PL tone or something quietly in the background, under 150hz or so.)

This causes the scanning to hang for long periods of time, or until I hit the scan button again.

Any idea why this is happening and how I can avoid it?

 

[trooperdude]

San Francisco 800 trunked system is conventional
Motorola 800, not P25.

The paramedics are encrypted, so perhaps the scanner is muting
the audio when it finds encryption on the channel and it hangs on
that muted channel ?

I know this happens to me occasionally on my 996T with
Onizuka AFS encryption.

Other options are local interference and inadequate signal strength
to track the control channel.

 

[rustyhodge]

What should I hear when the 996XT stops on encrypted traffic? I thought I had it set to ignore encrypted traffic. But this is happening on the SFPD dispatch channels, A4 and A6 groups seem to do it the most. There is some audio there, like a dead carrier with a subtone underneath it.

It could be local interference, I do live pretty close to the Bernal Hill radio site (2 blocks away from it), so it could be something there that's getting into the IF. I'll experiment with that a bit.

 

[rustyhodge]

Here it says: San Francisco County, California (CA) Scanner Frequencies and Radio Frequency Reference

"All San Franscisco City and County operations operate on this Motorola APCO-25 Smartzone system."

Things are working fine most of the time for the public safety channels / talkgroups with the exception of these dead carrier issues I'm having. So I don't think it's due to it being programed as P25 rather than conventional trunked.

 

[rustyhodge]

Found the fix. The "Mot End Code" needs to be set to Analog and Digital, rather than "ignore". That solves the problem.

 

[dougr1252]

Several of San Francisco's repeaters are hanging up or maybe they're testing something, so end code detection is the only way to get the scanner to go back to the control channel. They have this problem from time to time. It is an analog system, but they can also run P25 traffic which is mostly encrypted.