DP4801 does not hear all transmissions...

[dk5ras]

Hi,

I have a strange effect here in the German ham radio DMR networks...

Some certain transmissions coming from a DMR "hotspot" (one of those tiny boxes linking DMR with an integrated 10mW transceiver over the internet) can not be received by all radios. The crappy TYT MD-380 radios do receive it fine, while for example my beloved Motorolas (DP4801 and SL1600) just show a busy channel, with no audio at all. CC/TS/TG settings are fine, and the transmission appears in the correct TS/TG. It just does not unmute some radios. And even stranger, in our funny "linkage cloud" the DMR-MARC/Motorola repeaters transmit it correctly, the issue only shows on a BrandMeister/Hytera-repeater.

For sure it is some flag that is set wrong on the path through all the different networks.

What I hope to get through this post, what kind of flag in the DMR protocol could cause this? Maybe we could trace it down a bit easier if we get an idea WTF can cause such a behavior. We do not have access to a professional DMR tester, but we know how to use stuff like a SDR with DSD or gnuradio, wireshark, and the other normal debugging stuff an advanced hobbyist usually has around

Ralph, dk5ras.

 

[techman]

I have seen similar issues with dp4801 with emea firmware connected to private Motorola repeater network. For me it seems to have become more of an issue with 2.6 firmware.

The issues describe are almost exactly the same but I have not had time to experiment further to see if the other radios I also have experience the same issue.

If I have a chance over the weekend I will try and replicate the issue locally.


Sent from my iPhone using Tapatalk

 

[dk5ras]

Hmm, at least it does not happen in the Motorola repeater system, and the other guy who does not hear me should have a Hytera radio - but I will check this. Strange things do happen, this is for sure

Ralph.

 

[dk5ras]

It appears that it is solved. Has to do with a flag in the transmitting radio that get messed up somehow. See here the CPS info text:

Allow Interruption
This feature enables the radio to be interrupted during voice transmissions by radios that are Transmit Interrupt capable. After the radio has been dekeyed, a voice, emergency, or data transmission can follow. In order to configure a radio to be Transmit Interrupt capable, see the TX Interrupt Remote Dekey programmable button option, the TX Interrupt option under In Call Criteria, and Emergency TX Interrupt.


TX Interruptible Frequencies
This feature needs to be enabled if the frequency supports interruptible voice transmissions. For frequencies supporting direct mode (talkaround) interruptible transmissions, there is no over the air definition of slotting. Therefore this is a frequency and not a channel (slot) consideration. Enabling this parameter adds a slight increase to channel access times in certain situations but reduces the probability of collisions on the frequency. Since GPS and Data Revert Channels do not support voice calls, this feature should not be enabled on those channels. This is a channel-wide feature.

Somehow this got enabled when I started creating my codeplug years ago, and as I created all new channels by copying older ones, it spread through the whole codeplug.

In normal operation those flags do nothing bad, just through the DMR hotspot something gets mixed up in some certain situations. So until further notice, please see the issue as closed. Sorry for bothering you

Ralph, dk5ras.

 

[techman]

You bring up a good point which has been discussed here before with codeplugs which I think from memory has been tracked back to firmware updated over time not always cleanly upgrading code plug correctly and/or cloned from other radios and interesting events occurring with in the radio.

I will check mine just in case as well

Sometimes it is good to stop, create a fresh one with current cps and apply to radio

 

[dk5ras]

Yep, but in this case it was not a software error inside the radio or its CP, just a strange side effect.

I take this as a reminder being careful with enabling things I do not really need - thought it would be a good, polite idea allowing interruption, but I never needed it, and it did cost me a few hours of investigation

Ralph, dk5ras.