Trying to decode Cap+ system

[Matt Foster]

Apologies for the cross-post. I also put this in a Github issue before I found this group.

I'm trying to decode a MotoTRBO Capacity+ system. I've entered the three frequencies given by RR and assigned the LSNs to the appropriate channels. I never hear any audio. I have tested the audio output from User Preferences and confirmed it is working. I have observed the following...

• "Status" will show one of IDLE, ACTIVE, CALL or FADE
• The "To" TGID and Alias sometimes populate with expected TGIS info. I don't think I've ever seen "From" populated
• The "Channel Name" will show either Control or TRAFFIC

I've looked at the Messages pane, and it appears that sdrtrunk is at least "sort of" decoding the system, but I also see a fair number of "CRC Error" and "SYNC LOSS" messages.

From everything I've read, it seems that sdrtrunk should support Cap+, so maybe I just have something misconfigured.

Oh...I'm on v0.5.2 Final. I'm using a single RTL-SDR dongle.

Matt

[Matt Foster]

UPDATE - I am getting some audio, but not a lot. I can see on the waterfall that there is a lot more activity than what I'm hearing, but I am getting something anyway!

[Matt Foster]

UPDATE 2 - I have twice had sdrtrunk stop scanning the frequencies. I can stop/start and it will resume scanning for a while. If the frequency that it has stopped on becomes active, the status doesn't change.

[Michael Cadiere]

Link too the system on RR?

[Matt Foster]

https://www.radioreference.com/db/sid/11895

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[Matt Foster]

I got a screenshot with the site active. I feel like I have a pretty solid signal. The site is about 11 miles away, and it's VHF (151 MHz). I'm using an outdoor antenna. It's actually a 2m ham antenna, but it should be close enough to receive decently.

I also captured the messages pane while a voice call was going on that I was not getting any audio. I will attach both of those.

One question...what is an appropriate scan speed for a Cap+ system? I slowed mine from 200 ms to 500 ms, and subjectively it seems like I'm hearing a bit more.

Matt

[Matt Foster]

Another question...

Is there a way I can tell from the decoded messages what LSNs are paired to a particular frequency? It's my understanding that each frequency in a Cap+ system has two LSNs mapped to it, however, when I monitor a single frequency I see more than two (sometimes 5 or 6) LSNs in the decoded messages. It's confusing.

Any help is appreciated!

Matt

[DaveNF2G]

The Rest channel in a Cap+ system tells subscriber units where their activity is, so you might see references to channels other than the one you are monitoring.

[Matt Foster]

I'm still struggling with this Cap+ system. I have tried it as both a single, multi-frequency channel (i.e. with frequency rotation) and with the site's three frequencies each in their own channel. I rarely (perhaps 5% of the time) get decoded audio, even when the Messages tab is showing a continual stream of "BS VOICE" messages. Also, I have never seen anything on the Events tab. The Details tab always shows "Activity Summary - Decoder: DMR" and "Brand: Standard".

This morning, I captured a baseband recording (see link below) that should contain at least a couple of voice calls that produced no audio while BS VOICE messages were showing.. I'm hopeful that perhaps Denny or someone can inspect it to see what might be going on.

Matt

Baseband Recording

[DaveNF2G]

I would recommend monitoring the system with DSDPlus to make sure that it is in fact a Cap+ system and that you have the right channels.

[Matt Foster]

DSD+-FL does say that it's Cap+, and it tracks and decodes the system. My only issue with DSD+ is that its decoded audio is not nearly as good as sdrtrunk. sdrtrunk also says it's Cap+ in the Messages tab.