Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

oh3erv
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Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by oh3erv » Fri Nov 08, 2019 6:52 pm

Hi all,

I'm having problems with Motorola DM4801e and DM4601e radios when using OpenSpot2 and Brandmeister. Basically, the radios are more often than not failing to do the ARS registration to Brandmeister. When the radio starts up, or when I change a memory channel with ARS active, the radio will initiate a data call to the ARS ID (which in my case is the Finnish BM master server's 244999) and the ARS service responds to the radio. However, the data call very often times out and the ARS registration fails.

The radios are both using FW 2.9.0 and the OpenSpot2 is using the latest stable firmware. I do not have SMS intercept enabled in OpenSpot. Also, I have "Send no in-band data to modem" selected.

On the Motorola side, the radio has an ARS init delay of 0 and data call preamble is set to 780 ms. CSBK data is not enabled on the memory channels. Data call confirmation is enabled.

For comparison, when I use the radios through a Chinese MMDVM hotspot, the ARS registration does work and the radios transmit their positions properly. Also, when using the radios with Motorola repeaters connected to Brandmeister using IPSC, the ARS registration also always works.

Any suggestions as to what I could try?

Br,
Tuomas OH3ERV

oh3erv
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Re: Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by oh3erv » Fri Nov 08, 2019 6:55 pm

Not sure if it's related, but both the OpenSpot2's own log and Brandmeister's lastheard are reporting a call originating from my hotspot with both source and target ID as 0. I don't recall this happening with older OSP2 firmware.

oh3erv
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Re: Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by oh3erv » Fri Nov 08, 2019 9:21 pm

Updating this as I keep debugging...

I changed "Location data delivery mode" to "Unconfirmed" in the memory channel settings. The problem with data calls having source/destination ID 0 just got a lot worse. About half of the location data calls fail with source/destination ID 0. They are also visible in BM lastheard.

I also noticed that when the radios fail the ARS registration, there are lines in the log with something along the lines of "got duplicate frame in tc0, dropping". After those, the data call times out.

I will try to get a log of a successful and a failed ARS registration.

I think this may be more of a timing than a frequency offset issue, but how can that be as both the radio and the hotspot are running in direct mode and there should be no TDMA stuff going on?

oh3erv
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Re: Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by oh3erv » Sat Nov 09, 2019 6:46 am

I'm attaching some logs from ARS registration and location data delivery attempts.

When an ARS registration fails, this line is present:

homebrew: got duplicated frame on tc0, dropping

...and when it succeeds, it is not. This is also suspicious:

homebrew: received seqnum diff 252

Then with location data delivery attempts, there are a lot of these:

dmrcalltracker[0]: cc mismatch (got 2 expected 5)
dmrcalltracker[0]: cc mismatch (got 1 expected 5)
dmrcalltracker[0]: cc mismatch (got 0 expected 5)
dmrcalltracker[0]: cc mismatch (got 13 expected 5)

Another scenario when location data delivery fails is that there is a data call with both source and destination id of 0. These are not present in my log excerpts, but I did observe them yesterday. These also get logged in BM lastheard.

I'm running out of ideas here.
Attachments
oh3erv-osp2-logs.zip
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HA2NON
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Re: Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by HA2NON » Sat Nov 09, 2019 9:23 am

Please first run DMR AutoCal, or manually adjust RX offset for the lowest BER.
Norbert "Nonoo" Varga, HA2NON
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oh3erv
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Re: Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by oh3erv » Sat Nov 09, 2019 11:31 am

Thanks for the reply!

I have run AutoCal, it gives offsets between 100 and 200 Hz (mostly 200 so I have that set). But otherwise it did not seem to make any difference.

What does seem to make a difference is setting "Compressed UDP Data Header" to "None" in the radio's memory channel settings. That makes the problem almost nonexistent. However, I have understood that OpenSpot2 should support UDP data header compression. Perhaps this only mitigates the real problem causing the issue?

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Re: Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by HA2NON » Sat Nov 09, 2019 1:23 pm

Please use standard DMR messaging and turn off compressed UDP data header. It is also the recommended way for BrandMeister, see https://wiki.brandmeister.network/index ... ola/Radios
Norbert "Nonoo" Varga, HA2NON
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Re: Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by oh3erv » Sat Nov 09, 2019 1:27 pm

Uhm actually the page you are referring to recommends the "Compressed UDP Data Header" should be set to "DMR Standard" instead of "None". If I do that then the problem gets worse. Now with the setting at "None", it seems to be better.

Text Message Type has been set to DMR Standard all along. The BM page recommends it be set to Proprietary, I have tested that also but it does not seem to have an effect.

Investigating this further, I have noticed that BER in data calls varies from anywhere between 0.8 and 3 %, while with audio calls BER remains between 0 and 0.8 % (which I consider to be normal).

I also tried setting the modulation mode to 4FSK instead of 4FSK-RC but that made no difference either.

Disabling UDP data header compression did certainly help to mitigate the issue, but having followed the OSP2 log during the day it seems the underlying cause is yet to be discovered.

oh3erv
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Re: Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by oh3erv » Mon Nov 11, 2019 4:27 pm

Hi,

Any more ideas as to what I could try? Should I drop an e-mail to SharkRF support if you guys want to take a look at my unit for possible defects? Still giving high BER in data calls and errors about duplicated frames.

I have done AutoCal and BER in voice calls is below 1 % at all times. AutoCal reports a recommended offset of 200 Hz.

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Re: Motorola DP4801e/DM4601e failing ARS registration with Brandmeister

Post by HA2NON » Mon Nov 11, 2019 4:52 pm

Please try using a different server, as the duplicated frame error refers to the server sending frames duplicated to your OS2.
Norbert "Nonoo" Varga, HA2NON
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