So it's a problem with the SDS100 and SDS200 series. Given they're essentially the same radio and firmware, it makes sense. Or it may be a signal issue.
Using SDRTrunk with even crappier antennas I was able to pick up a lot of transmissions my SDS's seemed to be ignoring and treating like encrypted traffic. My favorite lists on my SDS's are set to monitor the control channels specifically for the sites I monitor. (A note about P25, P25 Phase 2 systems with TDMA enabled always broadcast their CC's in P25 Phase 1, non TDMA) They then "chase" to the frequency for the talk groups I follow when they transmit using the TrunkTracker function. However when it's a TDMA talk group its jumping to the SDS seems to have a like a maybe 20% chance of actually locking on the channel and not skipping over it. It could be a few things. My skipping over, my SDS scanners jump to the frequency, show the TG talking for like 0.2 seconds at best, then goes back to scanning, sometimes picking up the CC again, moving the the same frequency again, then skipping it again. This behavior is also how the SDS acts when it trunks to a encrypted channel, or signal it cant handle, I run into this a few times when I have ID search on and it finds a encrypted channel.
First possibility; Jumping from a P25 Phase I signal of the CC to a P25 Phase 2 TDMA TG may throw the firmware off, if there's a bug where it expects it to be the same type of signal. When it's not... it throws an error. I found out if I changed my favorites from scanning just the CC which had worked fine before, to scanning all of the sites frequencies instead, it had a much much better chance of locking onto the signal. It may also be because when it scans and finds a new frequency, as opposed to being directed to it by the CC, it may hold it longer analyzing it and not skipping over it like it does to me with just the CC.
Second possibility; I get about -95db to -99db on my SDS200 for all my sites using a small discone antenna in a window, which is fairly decent. It's 4 to 5 bars out of 5 on the SDS's signal meter. This hasn't changed with the TDMA being enabled. It could be the way TDMA works, how it "pulses" on and off for timeslots that may make it harder for the SDS's to lock on if the signal is any bit weak or anything shy of perfect. So people with stronger signal may not be having as many issues. They may just not have good firmware that enables it to lock onto weak signals on TDMA. Also, for all I know I could be in a area with Simulcast Distortion. On Phase 1 it may not have been an issue, but on TDMA Phase 2, that small small delay in the echo receptions signal may be enough to cause timing issues and thus decoding issues for the SDS series. I have tried with my normal global filter of "wide normal" that used to work just fine, as well as off. I'm testing "normal" filter as well to see where that gets me, but typically it never worked well for my environment.
This may be one some of the older x96 scanners are working on these sites better than the SDSx00 series scanners, firmware and reception issues and how they handle P25. Also why many SDR based solutions also work very well, as with my case using close to the scame setup with a SDR instead of a SDS Scanner.
... Bob.
