SDS100/SDS200: Conventional Channel DMR vs DMR One Frequency Reception

[Ubbe]

What is happening?

Uniden should look at it. When you scan conventionally it stays on the channel as long as the transmitter are on and there will be plenty of time for the scanner to properly decode the data. When you scan in trunked mode it looks at the control channel data on the time slot for a short time and if it doesn't see any active TG, or the wrong kind of data like bit error or encryption, it will continue to scan other systems.

There is some kind of issue with Uniden's DMR control channel decode process, as when I tried different firmwares it seems to have happened when they introduced RAS compatibility. DMR data uses forward error correction to improve reception during weak signals but that error correction are disabled when decoding a RAS system, making it receive much worse. I believe Unidens RAS mode are false triggered when receiving too many bit errors, the level when to switch to RAS mode are set incorrectly to a very low level of bit errors. Maybe Uniden needs to pay more license money if they want to detect RAS mode the proper way in the data frames but have instead done a simple bit error threshold trigger.

TRX scanners doesn't use the control channel and scans trunked DMR pretty much like a conventional system in their decode process and my experience are that Whistlers DMR decode quality are superior to Unidens.

SDS scanners filter can be set individually for each site and are used to filter out interference from other transmitters, that could introduce bit errors or reduce receive sensitivity. The IFX setting and the attenuator can also be used to reduce interferences.

/Ubbe

 

[dave3825]

Another update: Lankenau Hospital security will only append to a favorite as a conventional channel in Sentinel. In both Sentinel and ProScan, I cannot convert it to an OFT.

What version of @ProScan are you running? I just navigated to Lankenau Hospital security in Proscan and told it to append. It detected it as DMR and offered to enter it as OFT.

 

[garys]

Filters can and do affect reception.

As to the rest, I wouldn't wait for any firmware updates from Uniden.

I don't think trunking versus conventional affects sensitivity, but it might affect latency and dwell time. I'm not an engineer, so that's just a guess.

 

[rgchristy]

I used Sentinel. I was under the impression that ProScan didn't do database imports or updates. Thanks for the info.

What version of @ProScan are you running? I just navigated to Lankenau Hospital security in Proscan and told it to append. It detected it as DMR and offered to enter it as OFT.

 

[rgchristy]

More good info. I'll have to try the other filters, especially Invert. Thanks.

Filters can and do affect reception.

As to the rest, I wouldn't wait for any firmware updates from Uniden.

I don't think trunking versus conventional affects sensitivity, but it might affect latency and dwell time. I'm not an engineer, so that's just a guess.

 

[dave3825]

I used Sentinel. I was under the impression that ProScan didn't do database imports or updates. Thanks for the info.

It does as long as one is a Premium Subscriber to Radio Reference and you are.

If I see a new system pop up in the rr database, or am looking to create a favorites list, Proscan will import exactly what you see on rr database as opposed to Sentinel where it has to update every Monday updates. The minute you see something show up green, Proscan can grab it. Proscan can also import trunked systems that do not have any known / identified talk groups, unlike Sentinel. You just have to create 1 dummy tg and set the system to ID search.

 

[takheng]

I might have the similar issue. When I previously listen to a DMRT3 system and then switch to and hold on a DMR One Frequency system, SDS100 still identified this system as a DMRT3 system, and it stop RX even there are activities on that frequency. My solution is to HOLD on that system and then reboot SDS100, it display as DMR and RX returns normally.

 

[PE1MJG]

Good day,

i have also same issue with my SDS100E, when using conventional programming , it decodes DMR fine, stops scanning while receiving DMR.

When programmed as DMR One Frequency it continue whith scanning when a DMR signal is present.
However, when i put it manually on a DMR One Frequency , like my own DMR hotspot on 438.8 Mhz, it starts decoding DMR when a new transmission is starting. So it works , but it needs to receive the DMR signal from the beginning.

I have tested this like this, when the SDS is receiving the signal in DMR One Frequency, and it gives audio , i switch manually to another frequency and then direct switch it back to the DMR One Frequency , the same transmission of the DMR signal is still present.
What i then see is that the DMR signal is received, but not decoded, DMR is flashing in the display.
When the DMR transmission stops and a new DMR transmission begins, it is decoded again and audio is heard.

So in DMR One Frequency it needs some kind of synchronisation which is present during the beginning of the DMR signal.

If you are scanning within DMR One Frequency, it almost never happens that your scanner is starting listening on a frequency when a transmission starts. Therefore almost never receives DMR.

I know that every 360ms a voice synchronisation signal is send out.

Maybe it is possible to change the synchronisation part within the software so that DMR One Frequency is working.

Maybe after a new firmware update ?

Could anyone check this theory also ?

Thanks.

 

[Ubbe]

What i then see is that the DMR signal is received, but not decoded, DMR is flashing in the display.

I've never seen a blinking DMR text. What does that indicate?
Does it happen with firmware 1.22 for the SDS100E? I mapped out a new CAP+ system this summer but can't remember if it was prior to 1.22 or after, but at that time I ran all channels as OFT and had no problem to start monitoring in the middle of a conversation. So it might be a problem in 1.22 when programming a conventional channel as OFT?

But I have had similar issues for ages with DT3 and CAP+ systems that it sometimes skips over ongoing calls but usually improves when using extra long hold times.

/Ubbe

 

[PE1MJG]

Hi Ubbe,

DMR text which is flashing is the text which appears on the right side of the volume and squelch settings in your display.
During a good decode it is steady.
When receiving CAP it shows CAP+ , when receiving dPMR it shows dPMR.
It is indeed sw version 1.22 for SDS100E, forgot to mention.
I had program hold time of 5 sec. but it does not stop when it is scanning DMR one frequency.

unfortunately not many strong DMR stations in my area.
Only receive them with an external antenna, live in a small town.

Have also tried this with my Tytera portable HH, same outcome, decode was good from beginning, no decode when transmission has already been started.


I have made a movie of it, but that movie is 555 MB, so a little to big to attach.
I will try to make it a bit smaller, so you can see what i mean, a picture explains more then a page of text.

 

[Ubbe]

Have also tried this with my Tytera portable HH, same outcome, decode was good from beginning, no decode when transmission has already been started.

So blinking DMR text indicates a DMR signal but cannot decode any activity? But if you got the same problem with a Tytera then it has to be a system issue if scanner and HT behave the same?

I have 5-6 conventional channels programmed in one OFT system in the BCD536 and where active just now and when I force scan it decodes properly in the middle of conversations. I will program the same in the SDS100E and see if it behaves differently.

edit: My SDS100E works as it should and starts to monitor in the middle of conversations from conventional DMR channels programmed as OFT.

/Ubbe

 

[PE1MJG]

The test with the tytera was that i used the tytera to transmit a DMR signal instead of using my hot spot to transmit a DMR signal.
to test if the problem was not caused by my hot spot.

With both different transmitters i had same outcome.

I have programmed also conventional channels for DMR reception , and then i don't have this problem, then it will monitor in the middle of a DMR conversation.
But not in One Frequency DMR, it only starts to monitor when the DMR signal is received from the beginning of its transmission.

 

[TongSlinger]

I have experienced the same issues with OFT programming vs Conventional programed DMR. Conventional programming results in being able to receive the same DMR frequencies/TG's that i cant receive while OFT. Frequencies in focus are the 155.000's. Frequencies closer than 25 miles have no problem and receive fine in both programed setups, Frequencies farther away have issues receiving the OFT programming. I'm scanning DMR using a SDS200 and BCD996P2 and both scanner behave the same way with DMR. Is there any advantage to conventional vs OFT programmed frequencies. Other than being able to receive them (In this case)?
Thanks

 

[werinshades]

I have experienced the same issues with OFT programming vs Conventional programed DMR. Conventional programming results in being able to receive the same DMR frequencies/TG's that i cant receive while OFT. Frequencies in focus are the 155.000's. Frequencies closer than 25 miles have no problem and receive fine in both programed setups, Frequencies farther away have issues receiving the OFT programming. I'm scanning DMR using a SDS200 and BCD996P2 and both scanner behave the same way with DMR. Is there any advantage to conventional vs OFT programmed frequencies. Other than being able to receive them (In this case)?
Thanks

If you log Radio ID's (Uniden calls them UID's), you would need to set up OFT. If the system you monitor might use 2 separate slots for the same talkgroup (I have one system set up like this by me), you could text tag each TGID with the corresponding slot. Example is I have a DMR OFT with talkgroup 169 slot 1 is the hotel shuttle bus, while talkgroup 169 slot 2 is parking lot security.

 

[Ubbe]

Conventional programming results in being able to receive the same DMR frequencies/TG's that i cant receive while OFT. Frequencies in focus are the 155.000's. Frequencies closer than 25 miles have no problem and receive fine in both programed setups, Frequencies farther away have issues receiving the OFT programming.

Can you test by having those problematic frequencies programmed as both conventional and OFT and on the SDS200 make one field show D-Error and on the 996 you probably push Function and then Volume to display bit error. Then compare if there's any difference in bit error between conventional and OFT, you probably need to make a hold on OFT to make it start to decode.

Uniden could need that type of analyze info to find the problem in their firmware code. It seems to happen only in some specific systems, maybe a specific brand of DMR system. If it is range dependent then it might be that error correction issue that it doesn't use that feature under certain circumstances. I would like Uniden to change that RAS function from automatic to instead be user selectable and indicate on the display when it thinks it receives RAS.

/Ubbe

 

[PE1MJG]

Good day all, it has been a while since my last message.

i have informed the guy where i have bought the SDS100 with my problem with DMR One frequency reception.
he contacted Uniden and i had to do several test and i had to send logfiles to them.
I got a new firmware version from them to test, and that was even worse.
Send again logfiles to them, then they found that there was something wrong.
last week i received new firmware and have installed it and tested it.
DMR One Frequecy mode is now good working, when a transmission is received it stops scanning and starts to decode within a second.
before it was skipping it several times and decoding took sometimes at least 6 to 8 seconds before audio was coming out.

i am now able to receive my HotSpot in One frequency DMR mode while scanning, it stops now in the middle of a transmission and starts to decode it.

New software version i have is V1_22_02.bin, will ask them if it is ok to distribute it , as soon as i have an answer i will post it here, otherwise we have to wait until next upgrade is available for all.

 

[n1chu]

Good to hear. A F/W update should be expected… maybe then I will be able to program a ham DMR repeater, which, to date has been an unsuccessful endeavor…

 

[PE1MJG]

Hi Bill,

that should be possible even with the current firmware, you should program it as conventional , see below an example of how i did it for my hotspot.

 

[n1chu]

Hi Bill,

that should be possible even with the current firmware, you should program it as conventional , see below an example of how i did it for my hotspot.



View attachment 135100

OK, thanks. I’ll give that a try.

 

[PE1MJG]

Good day all,

just to inform you that i am not allowed to share the new firmware as it is not a commercial version ,
probably the changes for DMR One Frequency will be submitted into the latest firmware update. Not known when it will come out.