BCD436HP/BCD536HP: Could firmware update cause hearing only the dispatcher now? (on P25)

[heytae]

I've been googling this for days to no avail so I'm hoping the Uniden experts here can shed some light on this. I'm near San Jose, CA and I've been listening for years (BCD436HP) to a local P25 (phase 2 I think) sheriff department (Santa Clara County Sheriff West division on 155.700MHz). All of a sudden, I now only hear the dispatch traffic and none of the traffic from the units, but the dispatcher is responding to them in conversation. This did not happen for years until now. The dispatcher's transmissions are fairly clear, but they do cut in/out occasionally so I've tried lowering the Digital Threshold to Manual, then 6 (was 8) with no benefit. I was on a 4 years old firmware version and I just updated it to 1.26.00 recently, so could that be causing it? Is there any setting that could be causing me to hear only one half of the conversations? I've tried other antennas including a base station one and that didn't help. I'm still hearing only the dispatcher. I thought there might be a simple setting but I'm pulling out my hair about this.

 

[u2brent]

Could be adding encryption to the mobiles, This usually follows with the dispatch side being encrypted too
If your scanner goes totally silent on the frequency yet you know it's still in use that would be the first thing I'd suspect.

Santa Clara County, California (CA) Scanner Frequencies and Radio Frequency Reference

Scanner Frequencies and Radio Frequency Reference for Santa Clara County, California (CA)

www.radioreference.com

It's highly unlikely that a firmware update would cause this all of the sudden..

 

[pb_lonny]

I doubt it, must be something else that has changed.

 

[RichardKramer]

I've been googling this for days to no avail so I'm hoping the Uniden experts here can shed some light on this. I'm near San Jose, CA and I've been listening for years (BCD436HP) to a local P25 (phase 2 I think) sheriff department (Santa Clara County Sheriff West division on 155.700MHz). All of a sudden, I now only hear the dispatch traffic and none of the traffic from the units, but the dispatcher is responding to them in conversation. This did not happen for years until now. The dispatcher's transmissions are fairly clear, but they do cut in/out occasionally so I've tried lowering the Digital Threshold to Manual, then 6 (was 8) with no benefit. I was on a 4 years old firmware version and I just updated it to 1.26.00 recently, so could that be causing it? Is there any setting that could be causing me to hear only one half of the conversations? I've tried other antennas including a base station one and that didn't help. I'm still hearing only the dispatcher. I thought there might be a simple setting but I'm pulling out my hair about this.

RR says the Phase 2 system is the Sheriff primary comms; it could be that they are on that system and the Sheriff dept is still simulcasting just the dispatch on the old 155.7 freq. Looks like they are using encryption on the Phase 2 system. Have you tried listening to the input to 155.7 (159.21)?

Rich - N3VMY - KAG0096

 

[buddrousa]

P25 Phase II is trunking you are listing a P25 Phase I conventional pair from the reading in the database

Santa Clara County, California (CA) Scanner Frequencies and Radio Frequency Reference

Scanner Frequencies and Radio Frequency Reference for Santa Clara County, California (CA)

www.radioreference.com

 

[heytae]

It's possible that they've started encrypting just their mobile units first but I haven't found anything online about them moving to encryption. I wish there was someone else local here in the South Bay Area who could try it on their P25-capable scanner to help isolate the cause. Hoping someone local reads this.

Looks like they are using encryption on the Phase 2 system. Have you tried listening to the input to 155.7 (159.21)?

Rich - N3VMY - KAG0096

Oh that's interesting....How can I see where it states that they're using encryption now?

I think I can figure out how to change that channel's frequency only via the front keypad, but are you thinking that I might hear a mobile unit's voice (or digital noise if encrypted), if it's not too far away via their input transmission? The city of Cupertino, where I live and where they patrol, is only several square miles so that might work.

 

[hiegtx]

It's possible that they've started encrypting just their mobile units first but I haven't found anything online about them moving to encryption. I wish there was someone else local here in the South Bay Area who could try it on their P25-capable scanner to help isolate the cause. Hoping someone local reads this.


Oh that's interesting....How can I see where it states that they're using encryption now?

I think I can figure out how to change that channel's frequency only via the front keypad, but are you thinking that I might hear a mobile unit's voice (or digital noise if encrypted), if it's not too far away via their input transmission? The city of Cupertino, where I live and where they patrol, is only several square miles so that might work.

I suspect that Richard's comment, that they may be using the Phase II system but also simulcasting only the dispatcher's side on the old conventional channel (155.700) is the most likely scenario.

On the new P25 system, the Sheriff's talkgroups are encrypted. You can tell that by the DE in the Mode column.

The D means that they are using P25 Phase I, and the E means the talkgroup is encrypted full-time. Had the E been, instead, a lower case e, then that indicates that encryption was in use part of the time, but not all of the time. Your 436HP ignores encrypted transmissions, so you would not hear any "digital noise", and would not see the scanner stop on the encrypted talkgroup.

 

[buddrousa]

Our local dispatch center has the console programmed to transmit on bot the VHF and 800 Trunking System at the sametime.
Our local listeners with out Trunking only hear the Dispatch side and they removed the Mobile VHF link from the trunking system.

 

[heytae]

I suspect that Richard's comment, that they may be using the Phase II system but also simulcasting only the dispatcher's side on the old conventional channel (155.700) is the most likely scenario.

On the new P25 system, the Sheriff's talkgroups are encrypted. You can tell that by the DE in the Mode column.
View attachment 91908
The D means that they are using P25 Phase I, and the E means the talkgroup is encrypted full-time. Had the E been, instead, a lower case e, then that indicates that encryption was in use part of the time, but not all of the time. Your 436HP ignores encrypted transmissions, so you would not hear any "digital noise", and would not see the scanner stop on the encrypted talkgroup.

I learned something new today from you @hiegtx so thank you for sharing your knowledge. I've also gotten confirmation that other local scanner enthusiasts also lost the mobile half of the traffic, so my scanner's value to me just dropped by 98% (that's the only channel I listen to nowadays). At least I no longer have to spend more hours troubleshooting and banging my head against the wall. =)

This is probably the $64,000 question, but is there ANY scanner that can decrypt those encrypted channels? Wondering if there's a way, since our hobby has the will.

Thanks again.

 

[doctordialtone]

is there ANY scanner that can decrypt those encrypted channels?

No

Not possible.

That's why they encrypt.

 

[Ubbe]

Enter that single frequency manually, CHAN+frequency+CHAN and it will let you hear the encrypted datasignal and not mute or continue to scan. Then you'll know if they use encryption.

/Ubbe

 

[buddrousa]

YES a radio that belongs on the system PROGRAMMED by the SYSTEM ADMINISTRATOR.

 

[pb_lonny]

This is probably the $64,000 question, but is there ANY scanner that can decrypt those encrypted channels? Wondering if there's a way, since our hobby has the will.
Thanks again.

Nope, the whole point of encryption is to stop people listening....