Re: Release 3rd May
Posted: Mon May 04, 2020 5:41 pm
Thanks for the clarification. Certainly, such a system is very bothersome, especially as many radios use one hotspot.
OpenGD77
Amateur radio firmware for the GD-77, GD-77S, DM-1801, DM-1801A, RD-5R, MD-9600/RT-90, MD-UV380/RT-3S, DM-1701/RT-84 and MD2017/RT-82 radios
https://www.opengd77.com/
Release 3rd May
Page 6 of 6
Re: Release 3rd May
Posted: Mon May 04, 2020 6:49 pm
The ADF7021 AFC only works with constant carrier transmissions. It is not able to cope with TDMA pulsing transmissions as used by DMR. The bursts of noise in the unused timeslot cause it to loose lock.
Re: Release 3rd May
Posted: Mon May 04, 2020 8:34 pm
Is AFC functional and in use in MMDVM with the MMDVMHat boards on the other protocols (YSF, etc...)?
Marc
Marc
Re: Release 3rd May
Posted: Mon May 04, 2020 9:09 pm
I have no idea. However DStar and YSF are not TDMA modes so it may be.
Even without AFC a constant transmission is easier to demodulate as the detector can filter and average out the signal to determine a good threshold point. DMR is difficult to decode because the noise bursts in the unused timeslot upset any averaging circuit. Likewise any coupling capacitors will distort a TDMA waveform. This is a weak point of the MMDVM approach. DMR Chips such as the HRC-6000 in the GD-77 have specially designed decoders that do a much better job of recovering the data.
Even without AFC a constant transmission is easier to demodulate as the detector can filter and average out the signal to determine a good threshold point. DMR is difficult to decode because the noise bursts in the unused timeslot upset any averaging circuit. Likewise any coupling capacitors will distort a TDMA waveform. This is a weak point of the MMDVM approach. DMR Chips such as the HRC-6000 in the GD-77 have specially designed decoders that do a much better job of recovering the data.
Re: Release 3rd May
Posted: Tue May 05, 2020 12:37 pm
Thanks !!!
'73 de IU3MCP Giovanni
'73 de IU3MCP Giovanni
Re: Release 3rd May
Posted: Tue May 05, 2020 2:37 pm
Merci 
Re: Release 3rd May
Posted: Tue May 05, 2020 4:28 pm
There are often such situations (about which I wrote earlier) that there is such a trembling sound as in the attached recording. This appears on both GD77 and RD5R. From what I observed, this happens just like I listen to the correspondents for longer, but I did not notice it occur when I am a participant in the conversation.
https://drive.google.com/file/d/1yOstI0 ... sp=sharing
https://drive.google.com/file/d/1yOstI0 ... sp=sharing
Re: Release 3rd May
Posted: Tue May 05, 2020 6:05 pm
Yes, we have been observing this phenomenon in audio from time to time for a few days (or months).SO5AJG wrote: ↑Tue May 05, 2020 4:28 pmThere are often such situations (about which I wrote earlier) that there is such a trembling sound as in the attached recording. This appears on both GD77 and RD5R. From what I observed, this happens just like I listen to the correspondents for longer, but I did not notice it occur when I am a participant in the conversation.
https://drive.google.com/file/d/1yOstI0 ... sp=sharing
If when you listen to this audio, you turn off the phone and turn it on, the audio sounds right again. We have also been able to observe that with another receiver (md380) the audio is not distorted at the same time as the Opengd77 firmware does.
I thought it might be a DMR timeout issue, which is now at 13, and it's an odd number, and I did some testing with that number set to 14, but there's no difference.
What seems clear is that it is a firmware issue. It is also not very annoying, as it does not last too long and tends to recover well.
Re: Release 3rd May
Posted: Wed May 06, 2020 6:48 am
This topic has been going on for some time. The recording was made by a colleague who recorded my conversation and this effect also appears on his radio GD77 from time to time.
Re: Release 3rd May
Posted: Sun May 10, 2020 9:43 pm
Thank you for all your work and for the DCS support it is a much needed addition
Mike
Mike
VK3KYY wrote: ↑Sun May 03, 2020 10:21 amBecause of a major problem with the Tx Power level on the RD-5R, I have released a new version for all radios.
See
https://github.com/rogerclarkmelbourne/ ... /R20200503
The other major update is the inclusion of DCS support, thanks to KC7RBW, as well as some other GUI enhancements (by Daniel F1RMB), and also some bug fixes by me.
See the release change log on the Github page.
Note.
The power output on the RD-5R version is still far from correct, but it should no longer be overdriving the PA.
As things currently stand, I don't think there is any likelihood of the Tx power calibration being fixed on the RD-5R.
I simply don't have the time to take my RD-5R to pieces, and solder wires to the C6000 and AT1846S in order to reverse engineer the data being sent to these chips, in order to understand why the power output is so wrong.
And the last time I was in contact with Dzmitry EW1ADG, who ported the OpenGD77 to the RD-5R, he was in lockdown, and didn't have any access to anything like a logic analyser or a scope etc
I will contact Dzmitry again, and alert him to this major problem with the Tx power level, but I think it could be many months before he is able to investigate the problem.