Northern California services use P25 but with encryption turned off. They also have analogue repeaters. Presumably because that way they can still use old radios and don't have to worry about key rotation.
The audio quality on the analogue signal is a lot better than the P25 version, which is often harder to understand.
The P25 audio is digital, so it degrades worse than analog audio when signal quality is bad. You more quickly get to a point where it's not understandable at all, particularly if it's the signal coming from a handheld radio that's some distance away from the receiver.
The analog repeater is likely getting a high quality feed from the digital system, and then that's being broadcast at decent power from a tall antenna. It's starting with the best audio the system has to offer, has advantages in how it's broadcast, and degrades more gracefully.
I capture a lot of the P25 traffic in my area and there are times I can understand the dispatcher side of a conversation fine but the other end is too far away / too weak a signal and is unintelligible. The dispatcher's signal is coming from a fixed tower transmitting at higher power than a portable radio can manage.
Not like there’s not enough problems with P25… until the day they can deploy LLE (link-layer encryption) across all P25 systems, there will always be a way to gather some kind of intelligence about the system and its radio traffic.
(And the fact that it’s taking so long to implement link layer authorization, barely a scratch in the security dent…)
