Uniden SDS200 and BCD436HP Not stopping on DMR Cap + mid transmission

[MrCCTC]

I recently updated my SDS200 and BCD436HP to the latest firmware and have noticed less traffic on several Cap+ DMR systems I have entered as MOTO systems.

Upon closer inspection I was noticing that both scanners will not catch a transmission that is already in progress but instead will only pick up when a new transmission is being made. I have read a few others having similar issues but nothing suggested in those posts resolved it. I am starting to wonder if this has always been how it is and I just never noticed.
All NXDN systems I have entered are picking up mid transmission.

Do others have issues picking up DMR Cap+ systems when in mid transmission?

 

[Ubbe]

Uniden scanners needs to stop scan on the control channel slot and sync with its data, then decode the data and finally receive the data information that says what TG, if any, that are active on the site.

Try and set the system hold time to 5 sec and check if that solves it and if it actually stays 5 sec on the frequency. If it breaks out before the 5 sec have gone it means that something forced it to continue scan. That something can be that it though it was an encrypted transmission, a false decode of the data.

/Ubbe

 

[Bote]

I've noticed that Uniden scanners in general have trouble with Late Entry, going back 20 years or so.

 

[MrCCTC]

Uniden scanners needs to stop scan on the control channel slot and sync with its data, then decode the data and finally receive the data information that says what TG, if any, that are active on the site.

Try and set the system hold time to 5 sec and check if that solves it and if it actually stays 5 sec on the frequency. If it breaks out before the 5 sec have gone it means that something forced it to continue scan. That something can be that it though it was an encrypted transmission, a false decode of the data.

/Ubbe

I tried increasing the hold time but it just increases the likelihood of hearing the start of a transmission - does nothing to pick up late entry. Even when I am locked on the system I can see it blinking CAP+ and see the full signal bars but it will only pick up new transmissions. If I scan off the talkgroup mid transmission it will not stop back on the talkgroup until a new transmission is keyed up. The system I am testing it on is a 2 frequency Moto CAP+ system that is close by with strong signal. I know I have the LCN entered properly.

NXDN, DMR one channel and CON systems work fine - they will pick up mid transmission so it seems to be specific to Cap + systems. Maybe it is system specific (if the programmers didnt set up late entry on the system)? Can anybody else confirm if they are able to pick up a Cap+ system signal mid transmission?

 

[gary123]

This sounds like a late entry issue. As Bote mentioned Uniden is known for having issues capturing late entry transmissions. For now there is very little you can do to fix this aside from sitting on the system. Ubbes suggestion of holding on the CC for a longer period will alleviate the issue because your more likely to capture the initial key up.

Technically to identify the root cause you would have to know the CC data and know how often late entry or active channel data is broadcast. You would also need to know how often the MI is sent on the talk channel and slot. Obviously this is something way beyond the average user BUT if known its something Uniden would need should they decide again to update the firmware in the future.

 

[werinshades]

I tried increasing the hold time but it just increases the likelihood of hearing the start of a transmission - does nothing to pick up late entry. Even when I am locked on the system I can see it blinking CAP+ and see the full signal bars but it will only pick up new transmissions. If I scan off the talkgroup mid transmission it will not stop back on the talkgroup until a new transmission is keyed up. The system I am testing it on is a 2 frequency Moto CAP+ system that is close by with strong signal. I know I have the LCN entered properly.

NXDN, DMR one channel and CON systems work fine - they will pick up mid transmission so it seems to be specific to Cap + systems. Maybe it is system specific (if the programmers didnt set up late entry on the system)? Can anybody else confirm if they are able to pick up a Cap+ system signal mid transmission?

Similar situation on a couple CAP+ systems here and ended up utilizing a different filter for each system affected. Not changing the Global Filter setting, but changing the filter at the site level. Possibly using attentuator with/without a filter might be helpful too.

 

[Ubbe]

Maybe it is system specific (if the programmers didnt set up late entry on the system)? Can anybody else confirm if they are able to pick up a Cap+ system signal mid transmission?

I don't know if it can be programmed, it probably happens each 360mS in a superframe and Uniden scanners are supposed to alway stay 1.5sec minimum on a control channel, if it doesn't detect an encryption flag or receives too many bit errors. Come to think of it I've never found myself in mid sentence in a cap+ system, it's always the beginning of a PTT.

But my experience are that Uniden scanners miss too many calls when scanning control channels. Having a Whistler scanning in parallel that scans voice channels, or have another Uniden scan in conventional mode, shows how much that are missed in scan. But what I recall it worked fine in Uniden scanners until they added support for RAS mode in their firmware.

/Ubbe

 

[buddrousa]

Good catch Ubbe as is the case sometimes when you fix one thing in Firmware it breaks something somewhere else.