DSD+: LCN "S1/S2"?

Hey all,

Posting this here because the terms that one would use to search for this are too short for the search field. Apologies if it's been asked and answered before.

One of the frequencies on a Cap+ system I'm monitoring (with DSD+ 1.101pt) comes up consistently with the channel numbers S1 and S2. Everything else in this system comes up with "normal" channel numbers (1, 2, etc thru 10). I've asked around and the belief is that these indicate that DSD+ doesn't know what the channel numbers are for this frequency yet. Is that the case? Is there another means of identifying what they are?

Thanks in advance...

That is exactly the reason. If DSDPlus does not intercept the part of the datastream that gives the channel number assignment, then it only knows which slot is in use. If the conversation goes on long enough, eventually it will repeat the channel assignment.

I would try sitting on the frequency in question for a while to catch the channel info instead of scanning.

Thanks. Odd, though, I've been parked on that channel for a couple hours with plenty of traffic thru them, both rest and voice, and they're still showing up S1/S2.

Interestingly enough, I have channels 1 thru 4 and 7 thru 10 on this system, and no 5/6. I wonder if the freq is 5/6 and I'm just somehow not receiving the proper channel ID at all for them.

I'll keep monitoring...

Could be. I see the system has RAS enabled, which should only affect "real" TRBO radios, but it might be affecting DSDPlus' ability to decode properly.

DaveNF2G said:

Could be. I see the system has RAS enabled, which should only affect "real" TRBO radios, but it might be affecting DSDPlus' ability to decode properly.

Click to expand...

In my experience, RAS makes a relatively weak signal more difficult to decode in DSD+.

Hi folks,

Got two (and a half) questions on this topic.

(1) Could the presence of S1/S2 be possible if I have two (or more) unique systems mixed together? I've got DSD+ running on an SDR dongle and my 436 holding on the same frequency with its debug mode enabled. DSD+ is reporting Ch S1 is active with a call on tg 105 with RID 10223. The 436 is playing the audio and displaying tg 105 on its screen. The USB debug log shows TG 105 active with RID 10223 (though it shows both these data in hex) on LCN 10.

I've attached the DSD+ log (as 'CC.log') and the Uniden USB debug log (as 'putty.log') in case anybody wants to take a peek and see if they can help me out. The two logs definitely contain only data occurring during the same period in time (made sure there was a 'quiet period' before and after); fair disclosure, the SDR appears to have some errors in the signal (the two radios are not using the same antenna).

(1a) Would two different frequencies simultaneously providing data indicating a rest channel be an indication that I have two systems, or is it possible for a Cap+ system to have two frequencies announcing the rest channel at one time?

Question (2):

DaveNF2G said:

Could be. I see the system has RAS enabled, which should only affect "real" TRBO radios, but it might be affecting DSDPlus' ability to decode properly.

Click to expand...

How did you identify that the system has RAS enabled from what I mentioned in the above/original post?

Jay911 said:

Hey all,

Posting this here because the terms that one would use to search for this are too short for the search field. Apologies if it's been asked and answered before.

One of the frequencies on a Cap+ system I'm monitoring (with DSD+ 1.101pt) comes up consistently with the channel numbers S1 and S2. Everything else in this system comes up with "normal" channel numbers (1, 2, etc thru 10). I've asked around and the belief is that these indicate that DSD+ doesn't know what the channel numbers are for this frequency yet. Is that the case? Is there another means of identifying what they are?

Click to expand...

Good question, I've got at least two Cap+ systems here doing the same thing. One person in another forum has stated that it's a conventional repeater not part of the trunked system.

Problems with that theory are 1) if it's a conventional repeater not part of the trunked system, why is it showing up as part of the trunked system, and 2) on the Cap+ system closest to me which I've monitored the most, talkgroup conversations (same radios, same conversation confirmed by listening) on the S1/S2 repeater jump to other repeaters with normal channel numbers. So, it would stand to reason that the S1/S2 repeater is somehow part of the trunking rotation.

The other part of Problem #2 is that I've confirmed all frequencies at the location by monitoring and confirming which is which. Even with a spectrum analyzer no additional frequencies have shown up.

I'm wondering if it's a question of slight data corruption being caused by noise on the active channel; both of these systems are on the edge of my reliable reception area so sometimes have noise.

Hello,

I wonder if it is a bug in DSDPlus? The channel information gets split into two messages when dealing with 8 or more channels.
http://forums.radioreference.com/vo...g-thread-plus-raw-recordings.html#post2486983

It might be useful for the DSDPlus developers (and I am interested as well) to do a raw audio recording of the frequency when this situation occurs and upload it to a file site.

73 Eric

The console log shows that Jay was monitoring the rest channel on channel 9 (fifth repeater, slot 1). A voice call starts on channel 9 and the rest channel moves to channel 10 (slot 2). The DSD+ output does not show DSD+ picking up the changes in the rest channel's announcements.

It goes from no active calls:

10 111110 00010000 11 0 01001 00000000 00000000 00000000 00000000000000000000000000000000

To active call, TG 105 on channel 9:

10 111110 00010000 11 1 01010 00000000 10000000 01101001 00000000000000000000000000000000

But DSD+ decodes this as:

slot2 BS DATA DCC=1 CSBK Cap+ RestCh=10

There is no acknowledgement of the active call on channel 9.


However, Jay is using DSD+ 1.101 and the change log for 1.112 includes:

DSD+ 1.112 New Features
-----------------------

DSD+: Added detection and audio synthesis of MotoTRBO Dual Capacity Direct Mode (DCDM) signals

DSD+: Improved MotoTRBO Capacity Plus decoding/reporting

DSD+: Improved Restricted Access to Systen (RAS) detection


Is anyone out there running the latest DSD+ and monitoring a Cap+ system that has more than four RF channels? If so, does it properly display activity on channels 9-16?

Or, if Jay uploads a raw audio sample from the same channel, anyone with the latest DSD+ can test if it handles this.

I may not be in a position to make a raw recording for the remainder of the week, but we'll see.

I am unfortunately not in a position to get into the FastLane program right now... maybe later this summer.

Thanks for the analysis so far!

S1/S2 is not a separate repeater. DSDPlus uses that part of the display to indicate the slot(s) in use on the current channel when the number of the current channel has not been received yet. When/if the software receives a channel number indication in the datastream, it will place the data onto the corresponding channel number on its display.

Note also that this has nothing to do with whether any frequencies have been associated with particular channels in the software's files. All DSDPlus gets from the datastream are color code, slot, talkgroup, radio ID and channel number. The latest Fast Lane release also uses the Rest channel assignment in a Capacity Plus system.

Jay911 said:

Hey all,

Posting this here because the terms that one would use to search for this are too short for the search field. Apologies if it's been asked and answered before.

One of the frequencies on a Cap+ system I'm monitoring (with DSD+ 1.101pt) comes up consistently with the channel numbers S1 and S2. Everything else in this system comes up with "normal" channel numbers (1, 2, etc thru 10). I've asked around and the belief is that these indicate that DSD+ doesn't know what the channel numbers are for this frequency yet. Is that the case? Is there another means of identifying what they are?

Thanks in advance...

Click to expand...

Since DMR utilizes two talk SLOTS per channel DSD+ moves the display information to S1 or S2 when two talk groups are using that same channel. This denotes which talk group is on which slot. You'll only see that display if there is simultaneous talk group activity.

Hello,

Each slot is associated with a Channel on a Capacity+ system. To avoid confusion there are two slots per frequency as Channel has different meanings. The S1/S2 is likely the result of a bug in the channel handling and maybe corrected in later versions of DSD+. The raw audio is useful to check if DSD+ is decoding things properly.

73 Eric

I managed to free up some $ for FastLane and the 2p10 version is performing much better on this system. Very few occurrences of S1/S2, if any.

Of the frequencies I thought were in the system, I've now figured out the LCNs for four of the six. The other two are behaving differently from the main group.

One frequency occasionally broadcasts "idle bursts"/rest channel data, but seemingly never voice. As the identified freqs in the system are LCN 1, 2, 4, and 5 (LSNs 1/2, 3/4, 7/8, and 9/10), I presume this may be LCN 3/LSN 5/6 which is not being used for some reason. (I have never seen LCN3/LSN5/6 identified or used on this system.)

The other frequency seems to have "rest channel" data being broadcast continuously, including the all the other LCNs/LSNs as described above and their activity, as if it was a standard trunk system's "control channel". It identifies as Cap+ so it's not a Con+ CC. Curious - is this perhaps a better candidate for LCN3 (as per my guess for the other freq above) or is this by chance a single-freq Cap+ "system" linked to the other (four-frequency) system?

EDIT: I should mention that this second frequency (the one with the constant "rest channel" data) is possibly identifying itself as LCN 1. I had set up my dsdplus.frequencies file so that it would identify LCN 1 as 860.8125 (the one it identified as LCN 1/LSN 1/2), and when I tune FMP24 to 860.5625 (the "constant rest channel"), DSD+ seems to automatically retune FMP24 back to 860.8125. Removing that line from dsdplus.frequencies got rid of that particular problem.

Jay911 said:

The other frequency seems to have "rest channel" data being broadcast continuously, including the all the other LCNs/LSNs as described above and their activity, as if it was a standard trunk system's "control channel". It identifies as Cap+ so it's not a Con+ CC. Curious - is this perhaps a better candidate for LCN3 (as per my guess for the other freq above) or is this by chance a single-freq Cap+ "system" linked to the other (four-frequency) system?

Click to expand...

Hello,

That is likely a Cap+ data channel. I received a Cap+ system up in Montreal that had a frequency like that.

73 Eric

Okay, that makes sense, thanks!

DSDPlus does not always remove the Rest indication from the channel activity indicator when the Rest channel is reassigned. I have seen as many as four channels with the Rest indication at one time.

I haven't seen recent releases do that.