OpenGD77

Hi,

My first brand new Radioddity GD77 arrived last week. I installed OpenGD77 custom firmware in it yesterday.

I got audio reports from other DMR users that the signal has pulsed interference. The DMR receive is Ok but the transmitted really has pulsed noise. Also the audio in FM mode has interference both in receive and transmit. Level of the back light has only minor influence to the audio interference. I am not using external microphone, only the radio it self.

Is this related to new hardware or not, I don't know. Ari OH7FES has similar problems, mine seems to be even worse. I try to record the audio and publish those files later today.

The serial number of my radio is: S/N 1911A00744

I like to participate the project, is there any instructions how to setup building environment and build the firmware? I have already downloaded and installed the MCUXpresso IDE.

73 de VA

oh4va wrote: ↑

Thu Apr 02, 2020 8:17 am

...
Is this related to new hardware or not, I don't know. Ari OH7FES has similar problems, mine seems to be even worse.
...

It is. Many friends, who have GD-77 from few years ago, don't have such issues, but those who bought it sooner, cause of OpenGD77 project, have same problems as you do, I heard it personally. So, it's just worse quality control, or cheaper parts more likely. Maybe replacing mic would help...

This is normally caused by using an external mic

I have 5 GD-77 radios and none have this problem with the internal mic

Please try to use this modification for external microphone:

https://owenduffy.net/blog/?p=9219

https://owenduffy.net/blog/?p=9326

https://owenduffy.net/blog/?p=9313

https://owenduffy.net/blog/?p=9537

https://twitter.com/axelko/status/1027334519509135361


I have used an external microphone from UVR5 with my GD-77 and where added 10µH choke and works very well.

VK3KYY wrote: ↑

Thu Apr 02, 2020 10:27 am

This is normally caused by using an external mic

I have 5 GD-77 radios and none have this problem with the internal mic

I know. As I wrote before "I am NOT using external microphone, only the radio it self."

My question again. Is there instructions how to build the firmware by myself? I would like to fiddle with the code and try to solve the problem.

73 de VA

Here is one audio sample recorded today, FM mode transmission received with a Kenwood TM-V71E mobile radio and recorded trough the speaker with TASCAM DR-05.

Link to the audio clip http://li1426-150.members.linode.com/au ... _fm_tx.mp3

And here is the same clip with FT-70D and DM380 as a reference, http://li1426-150.members.linode.com/au ... _fm_tx.mp3

73 de VA

oh4va wrote: ↑

Thu Apr 02, 2020 10:49 am

My question again. Is there instructions how to build the firmware by myself? I would like to fiddle with the code and try to solve the problem.

The building instructions were too close, just behind a corner waiting me to find, https://github.com/rogerclarkmelbourne/ ... evelopment

73 de VA

Maybe someone want to take a look to this one and confirm this please.

i can confirm this audio distortions(as receiving station), have been talked to OH7FES and OH4VA, it seems this issue comes only this year radio models, it is somehow tied to background lighting because oh7fes was able to get rid of it when put certain setting.

Im guessing it is something to do with pwm driver of background led, OR the cpu cycles count there what was an issue some time ago on baofeng(and code was changed). This going to be hard to replicate because it is only on very new radios. My radios is from Q4 last year and a couple year old has no issues.

Want to remind, the issue comes only without a microphone plugged(just bare radio without anything connected) and only with opengd77 (on factory firmware no problem)

riku OH1E

Exact same issue here. Just bought the rig earlier this week from Amazon. It shipped with the current official firmware, v4.2.8.

If the backlight is on, I get the same hum/motorboating as the others have demonstrated in their sound files. Both FM and DMR. Internal or external mic, doesn't matter. Turn the backlight off and the noise goes away.

And as mentioned, the problem doesn't exist in the stock firmware. I was going to try older versions of OpenGD77 to see if there was a specific version in which it started to happen, but I could only find the two releases at https://github.com/rogerclarkmelbourne/ ... /releases/ .

Hopefully I'm not piling on here, but thought I would mention it since only a few others have.

Thanks,

Brad N8QQ

The backlight PWM noise problem has been logged as an issue.

https://github.com/rogerclarkmelbourne/ ... issues/521

I don't personally have time to fix it.