GD-77S Trouble with OpenGD77S Package

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WB5AGZ
Posts: 2
Joined: Mon Jun 14, 2021 3:47 pm

GD-77S Trouble with OpenGD77S Package

Post by WB5AGZ » Thu Jun 17, 2021 3:19 am

This posting is about the GD-77 S which is the radio without the
screen and keyboard. I recently purchased a GD-77 with a screen
and keyboard and it is running the OpenGd77 software and firmware
with no complaints at all.

I installed the GD-77 S version of OpenGD77 on the GD77 S
first and initially thought everything was wonderful. I could
now set the multiple power levels starting at 50 milliwatts, etc.

One, however, began to notice problems with the radio as
soon as I began to have conversations with other amateurs using a
Shark OpenSpot 3 hotspot.

What appears to happen is that the GD-77 S is having
difficulty transitioning from transmit to receive mode after the
PTT is released. This is kind of odd because by definition, DMR
requires switching from TX to RX at the end of each packet cycle
and a packet cycle is around 30 milliseconds, hence the
machine-gun-like popping sound one can hear when the radio is
transmitting near an audio system such as computer speakers.

Tests with a second receiver found that the GD77 S
frequently continues to transmit an unmodulated carrier at a low
level for up to 20 seconds after PTT release at least on 420-450
MHZ.

The LED also flashes 3 times at about 4 flashes per
second starting at 5 seconds after PTT release. There is a
5-second interval then another 3 quick flashes and so on for 3
loops.

After that, the radio fully goes in to receive mode and
all is well. My theory is that some part of the microprocessor
in the radio immediately detects an anomaly and the flashes are a
low-level alarm signal.

While in DMR mode, the receiver is also deaf during this
foul-up period. The deafness could be due to the transmitter's
continuing to transmit on the same frequency as the receiver is
receiving or the receiver may disable every time the transmitter
is active.

Sometimes, the lingering carrier is not heard but the
receiver still does not hear anything for up to 20 seconds.

Strangely enough, the radio works with external repeaters
or full duplex systems in which the transmit and receive
frequencies differ. The LED still gives the 3-flash distress
signal, however, but one's ears hear a working radio so all is
closer to well but still not.

Since this is really not an acceptable situation, I would
like to roll back the GD-77 S to Radioddity's firmware but after
the OpenGD upgrade, this apparently erased all of the identifying
information that Radioddity's firmware updater uses to re-flash
the most basic parts of the radio.

If one runs the stock Radioddity installer or CPS, the
radio does not show up at all even when in DFU mode which is
Radioddity's name for programming mode which is turning on power
while holding down both the black and blue buttons under the PTT
button.

The ideal solution would be some sort of reverse process
to reinstall enough of the right information in to the radio to
make the Radioddity installer see the radio again.

Second-best would be a process where by one can use the
OpenGD tools to rebuild the ability for Radioddity's installer to
communicate with the radio.

Right now, the hardware is perfectly good but basically
a rubbish scanner and I already have a hotspot so I would just
like to make the GD-77 S whole again. There has got to be a way.

I also want to make abundantly clear that I am not angry
at anybody involved. I would not at this point recommend that
anybody install the GD-77 S version on a working GD-77 S because
while many people have had no trouble, at least one other person
reported exactly the same issues but the OpenGD software works
exactly as hoped for on a GD-77, the one with the screen and
keyboard. I also have purposefully placed a space between the 77
and the S for the GD-77 S radio so that readers with speech
enabled hear it as the S kind of disappears when written properly.

Anyway, Had I known I could save all the memory in the
radio to have as a lifeline, I would have done so but I failed to
do so and that probably would have brought it back but this has
been an exercise in lost opportunities from the get go so I guess
that one is on me.

Thanks for any solutions to this problem since the radio
in question is about 18 months old and not otherwise broken.

Martin McCormick WB5AGZ

User avatar
F1RMB
Posts: 2488
Joined: Sat Nov 16, 2019 5:42 am
Location: Grenoble, France

Re: GD-77S Trouble with OpenGD77S Package

Post by F1RMB » Thu Jun 17, 2021 4:28 am

Hi Martin,
martin wrote:
Thu Jun 17, 2021 3:19 am
This posting is about the GD-77 S which is the radio without the
screen and keyboard. I recently purchased a GD-77 with a screen
and keyboard and it is running the OpenGd77 software and firmware
with no complaints at all.

I installed the GD-77 S version of OpenGD77 on the GD77 S
first and initially thought everything was wonderful. I could
now set the multiple power levels starting at 50 milliwatts, etc.

One, however, began to notice problems with the radio as
soon as I began to have conversations with other amateurs using a
Shark OpenSpot 3 hotspot.

What appears to happen is that the GD-77 S is having
difficulty transitioning from transmit to receive mode after the
PTT is released. This is kind of odd because by definition, DMR
requires switching from TX to RX at the end of each packet cycle
and a packet cycle is around 30 milliseconds, hence the
machine-gun-like popping sound one can hear when the radio is
transmitting near an audio system such as computer speakers.

Tests with a second receiver found that the GD77 S
frequently continues to transmit an unmodulated carrier at a low
level for up to 20 seconds after PTT release at least on 420-450
MHZ.

The LED also flashes 3 times at about 4 flashes per
second starting at 5 seconds after PTT release. There is a
5-second interval then another 3 quick flashes and so on for 3
loops.

After that, the radio fully goes in to receive mode and
all is well. My theory is that some part of the microprocessor
in the radio immediately detects an anomaly and the flashes are a
low-level alarm signal.

While in DMR mode, the receiver is also deaf during this
foul-up period. The deafness could be due to the transmitter's
continuing to transmit on the same frequency as the receiver is
receiving or the receiver may disable every time the transmitter
is active.

Sometimes, the lingering carrier is not heard but the
receiver still does not hear anything for up to 20 seconds.

Strangely enough, the radio works with external repeaters
or full duplex systems in which the transmit and receive
frequencies differ. The LED still gives the 3-flash distress
signal, however, but one's ears hear a working radio so all is
closer to well but still not.

Since this is really not an acceptable situation, I would
like to roll back the GD-77 S to Radioddity's firmware but after
the OpenGD upgrade, this apparently erased all of the identifying
information that Radioddity's firmware updater uses to re-flash
the most basic parts of the radio.

If one runs the stock Radioddity installer or CPS, the
radio does not show up at all even when in DFU mode which is
Radioddity's name for programming mode which is turning on power
while holding down both the black and blue buttons under the PTT
button.

The ideal solution would be some sort of reverse process
to reinstall enough of the right information in to the radio to
make the Radioddity installer see the radio again.

Second-best would be a process where by one can use the
OpenGD tools to rebuild the ability for Radioddity's installer to
communicate with the radio.

Right now, the hardware is perfectly good but basically
a rubbish scanner and I already have a hotspot so I would just
like to make the GD-77 S whole again. There has got to be a way.

I also want to make abundantly clear that I am not angry
at anybody involved. I would not at this point recommend that
anybody install the GD-77 S version on a working GD-77 S because
while many people have had no trouble, at least one other person
reported exactly the same issues but the OpenGD software works
exactly as hoped for on a GD-77, the one with the screen and
keyboard. I also have purposefully placed a space between the 77
and the S for the GD-77 S radio so that readers with speech
enabled hear it as the S kind of disappears when written properly.

Anyway, Had I known I could save all the memory in the
radio to have as a lifeline, I would have done so but I failed to
do so and that probably would have brought it back but this has
been an exercise in lost opportunities from the get go so I guess
that one is on me.

Thanks for any solutions to this problem since the radio
in question is about 18 months old and not otherwise broken.

Martin McCormick WB5AGZ
All the problem you're experiencing were fixed, hopefully, into the latest beta (released after last Sunday), you need to update your 77S again (I wrote a message about the 77S issues, https://www.opengd77.com/viewtopic.php? ... =80#p14950).

About the LED flashes, it's a normal behaviour of the OpenGD77 running on a 77S, but in the latest release, the color was messed up (red instead of yellow). There is no low level alarm stuff in any way, all of the problems were related to the same bug.

So, grab the latest beta firmware here https://www.opengd77.com/downloads/PublicBeta/firmware/, and report back (I tested it locally for the last days and it works as expected).

About reverting back to the official firmware, like other supported radios, using the official tools is the way to go. Nothing is "erased" from the radio, it's all about the PC softwares/drivers. Hence, you're better off uninstalling OpenGD77 related software/drivers, and install the Radioditty ones.



Cheers.
---
Daniel

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