New owner/user - initial impressions

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g0hww
Posts: 19
Joined: Mon Aug 31, 2020 7:56 pm

New owner/user - initial impressions

Post by g0hww » Fri Sep 11, 2020 1:14 pm

Greetings,

I am a new owner of a GD-77, which I have had for 5 days now. As a Windows hater and dedicated Linux user, I have had to overcome my loathing of Microsoft, bite the bullet and setup a Win10 VM in Virtualbox in order to wrangle this new radio.

Thanks to Scott, AF6MQ and Dale, VK5FSCK who both responded to my calls for clues on TG98977 and convinced me to borrow a physical Windows machine in order to perform the initial FW upload of OpenGD77 into the radio. I have subsequently been able to wrangle it via the CPS in the Win10 VM relatively painlessly.

I am not new to DMR, having had an MD390G for a couple of years, which I have had running Travis Goodspeed's MD380Tools firmware. I have always found this to be a little flaky, with many unexplained reboots of the radio occurring every day. I found that reboots happened more frequently when the radio was scanning, and attempted to mitigate those reboots by configuring a channel for auto-scan, such that after a reboot whilst scanning, the radio resumed scanning as the channel selection via the rotary switch made the selection of scan mode persist, unlike the outcome of a reboot if scanning had been initiated via the menu or a soft-key function. The MD390G also seemed to have issues with some DMR transmissions causing it to latch up in a loop repeatedly decoding and outputting the same syllable of speech until I twiddled the channel selector/encoder which would clear the issue.

Initially I uploaded the latest stable OpenGD77 FW, and after a couple of hours of operation, updated to the latest unstable version using the CPS.

Whilst I am generally pleased with the capabilities and features of the OpenGD77 firmware, I have noticed some issues and would appreciate any comments on them.

1) Sometimes, received DMR audio seems to have a squealing noise added. The squealing noise is not present on the same signal being received on my MD390G.
2) Sometimes, received DMR audio seems to have a motor-boating noise added. The motor-boating noise is not present on the same signal being received on my MD390G.

These artefacts of the received DMR audio on the GD-77 seem to usually go away If I power cycle the GD77 (I am sure that this is the case for the motor-boating noise, less sure about the squealing, will try and confirm). The GD-77 is equipped with a better antenna than the MD390G, so it seems unlikely that this is caused by poor SNR on the DMR signal.

3) Also, unfortunately, I find that the GD-77 now reboots spuriously at least as often as the MD390G, perhaps as much as 9 times in an 8 hour period.

4) There seems to be no way to ensure that after a spurious reboot, scanning is resumed. If I have wandered out of the room when the radio reboots, I would have to check the display of the radio to determine whether or not it is still scanning.

It would be useful if anyone could confirm whether they experience any of these issues, whether they think the issue may be hardware or firmware related and whether the issues may be related to the current use of latest unstable FW as opposed to latest stable FW.

Cheers, 73

Darren, G0HWW

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kd2lh
Posts: 312
Joined: Mon Dec 02, 2019 2:44 pm

Re: New owner/user - initial impressions

Post by kd2lh » Fri Sep 11, 2020 4:39 pm

Hi Darrin, and welcome to the project.

I cannot confirm those problems. No spontaneous reboots have occurred on any of my GD77 radios. I'm using a recent version of the unstable firmware.

You might double check how close your unit is to the frequency your MD390 is on. If you have a hotspot that doesn't have AFC (Like the JumboSpot) you might double check to see how close you are to it's frequency (the RXOffset and TXOffset settings may be setup for your MD390 radio).

If you find the GD77 is slightly off frequency, you have the option of altering the hotspot, or altering the GD77's tuning. i would only do it if a precise frequency standard is available...

Marc

W9YA
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Re: New owner/user - initial impressions

Post by W9YA » Fri Sep 11, 2020 8:59 pm

Hi Darrin;

I'm also new to the project, this week in fact.

I managed to do the firmware install (FirmwareLoader-Linux.exe) under mono (archlinux conversion of an x86_64 chromebook), the codeplug creation et al in opengd77cps.exe under wine (same laptop), and moving codeplugs back and forth to the radio with gd77transfer.py (again on the same laptop).

i.e. NO WINDOWS !! - You can find some more details on my New owner/user thread on this same OpenGD77 forum area. The tools are all available via links from various forum threads herein.

(Only thing missing from opengd77-linux is a tool to replicate the opngd77 support section of the extras menu...et al. <- Dunno how critical this is though.)

es vy 73 om de "baab" w9ya

P.S... I also run the Travis Goodspeed code in both a md380 and a md-390. I am not experiencing the rebooting issues that you seem to be having. I am wondering if this isn't more of a "localized" issue of some sort ? That is to say "local-to-you". I also have yet to need a reboot on the "stable" version of the opengd77 firmware.

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Zl1XE
Posts: 110
Joined: Fri Jul 24, 2020 12:25 am

Re: New owner/user - initial impressions

Post by Zl1XE » Fri Sep 11, 2020 9:23 pm

Hi Darrin,
On this forum reboots have been associated with too much RF. Some people have had success with external aerials and chokes on the usb lead. YMMV

g0hww
Posts: 19
Joined: Mon Aug 31, 2020 7:56 pm

Re: New owner/user - initial impressions

Post by g0hww » Thu Feb 25, 2021 12:41 pm

Hi again.

I've picked up the FW versions that have been coming out and am now on FW from Jan 19 2021 on my GD77. I thought it would be worth posting my longer term impressions and experience.

I have learned that the squealing audio is instability in the audio amp when the battery is fully charged, and that this becomes less of a problem once the battery voltage drops a bit. I have learned to live with this, but I would be interested to learn whether this affects all GD77s, the majority or just a few.

I do still experience what I previously described as motor-boating DMR RX audio. This is fairly rare and can not be deliberately triggered. It typically happens when listening to the local DMR repeater on 70cm, which comes in at S9 when the GD77 is in one of its usual places on the window-sill near my desk. It doesn't seem to happen when listening to my pistar hotspot (end stop signal). The effect on DMR RX audio sounds to me as if TDMA frames are being missed, though this is purely a subjective notion. The issue can be resolved by power cycling the radio, or quickly switching to a different channel and back again. When the issue occurs, the same signal can be clearly received on a MD-390 sat next to the GD77, so I am fairly convinced that it is a quirk in the OpenGD77 firmware that is causing this. I have tried to trigger this deliberately by changing radio/antenna orientation, rapid movement of the radio/antenna, signal blocking with metallic obstacles, etc. but to no avail. My best theory at this time is that it might be triggered by multipath signal reception. I have a notion that when it occurs, it does so after I hear a vehicle drive past the house in a direction towards the DMR repeater. It also seems less prone to occurring in the evening/night when there is less vehicular traffic going past. I used to have 2 channels configured in the zone for TS1 and TS2 and would leave the GD77 scanning between them. I have recently changed this approach, now have a single channel for the repeater and use TS filtering instead. This has made no difference to this glitchy audio issue.

Also, the radio still seems to spuriously reboot fairly often (a few times per day), though I typically only notice when I hear the startup tones. Checking the length of the Last Heard list gives me a good idea whether or not it has rebooted when I haven't been paying close attention. I have been unable to ascertain any specific scenario in which this is happening.

I am fairly convinced that neither the glitchy DMR RX audio or the spurious reboots are caused by the local RF environment. Likely candidates for strong local signals not under explicit manual control are my 2m APRS digipeater running 5W into a co-linear mounted on a flagpole above the garden shed, and the Pistar hotspot here in the house. Deliberate exposure to these signals seems to have no effect.

I am very grateful for all of the effort that is going into this project and hope that I don't sound too much like like a whining pommie.

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