Have you ever heard these Sheriff talkgroups used?

[Gamefreak88]

Have you ever heard these?

Sheriff Bomb/Arson
Sheriff Homicide 1
Sheriff Homicide 2
Sheriff Off Road Enforcement

I have heard the Off Road Enforcement a few times, but it was difficult to understand. I believe it relates to desert incidents, and is probably on the RCS East only.

I'm tempted to remove the first 3 just on the basis of clutter. In 2 years of scanning 24/7, I have NEVER seen their hit count go above 0.

 

[K6CDO]

The first three are used when the units are active.
ORET is a detail that usually operates on holiday weekends in the remote areas. If there isn't a unit on that TG in your area, you will not know that TG is in use.

 

[Gamefreak88]

Ok well that explains the Off Road Enforcement, but the first three have NEVER been active in 2 years as far as I can tell? I have 5 scanners, with at least 1 or 2 on at any given moment, all capable of receiving those talkgroups. I've been to dozens of bomb/arson incidents with them on scene, and they never talk on those talkgroups. Either they're unused or encrypted.

 

[disp10]

Over several years of using Unitrunker to monitor the RCS I have 0 hits on the Bomb/Arson talkgroup. The Homicide talkgroups have been used, but infrequently.

 

[Gamefreak88]

What happens if you have an encrypted talkgroup programmed in? Will it just be heard? Will it play scrambled audio? I'm just wondering if it is encrypted? I've never heard bomb-related radio traffic other than SWAT, on their own talkgroups, saying "they" (bomb tech's) are moving the robot in to position. It would make sense to me that bomb/arson be encrypted. You don't need a wackjob listening in knowing when and where the responding units are.

 

[inigo88]

The scanners you list in your signature automatically mute any trunked talkgroups carrying encrypted audio. Narcotics, Homicide and Bomb/Arson all have radios capable of encryption (at the flip of a switch). I would bet that's why you've never gotten any hits.

 

[puzzleriddle]

I've had the psr 500 & PRo197 for about 3 years .. THEY DO NOT mute enc Frequencies or Talk groups

 

[W6KRU]

I've had the psr 500 & PRo197 for about 3 years .. THEY DO NOT mute enc Frequencies or Talk groups

The San Diego RCS is a Moto Type II Smartzone with a 3600 bps CC. If an initial channel grant is for an encrypted subscriber on an encrypted TG, a PSR-500/600 or a PRO-106/197 will ignore it and will not follow that TG. If the initial CG is for an unencrypted subscriber, the scanners will switch to the TG.

On a true P25 system with a 9600bps CC, things are done differently and your statement is true.

 

[inigo88]

I've had the psr 500 & PRo197 for about 3 years .. THEY DO NOT mute enc Frequencies or Talk groups

Like DDan said, you aren't entirely correct. Motorola trunking encrypted talkgroups are muted. Encrypted conventional frequencies (i.e. Border Patrol using a local example) are NOT muted.

The reason for this is because Motorola trunking systems use something called a "Status Bit", which is a number added to the base talkgroup ID to create a different talkgroup ID. This used to play havoc on scanner listeners before scanners were created with the ability to "ignore status bit," because the same talkgroup would show up as different numbers depending on special features that were being used.

A few examples are Multi-Select (MSEL) patches, or encryption. So GRE decided with their PSR scanners (and their Pro-96 before it - which they built for radioshack) would automatically ignore the encrypted status bit. Since conventional P25 has no status bit, there was no obvious way for them to tell the scanner to ignore when it was encrypted (at least not without spending R&D money to figure out a new way).

Thus, your scanners don't ignore conventional P25 encryption, but they DO ignore Motorola trunking encryption (both analog & P25). Unless you scan all the trunking frequencies in conventional mode (or use decoding software), you would never know those encrypted talkgroups were in use.

 

[WayneH]

Since conventional P25 has no status bit, there was no obvious way for them to tell the scanner to ignore when it was encrypted (at least not without spending R&D money to figure out a new way).

P25 conventional does specify when the transmission is encrypted it's just that the earlier GRE scanners only looked at a certain amount of the P25 data. And unfortunately it's a limitation of the device as it cannot be added with a DSP or firmware upgrade (same with P25 RID and TG info).