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Folks,

I have today tried using FT8 CN on my Google Pixel 6A with QMX. Having had the same problem as others with USB C to C cables, I reverted to USB C to A and then an adapter to C in my phone. That worked and the app decodes very well and seems to have full CAT control. The app is very impressive!

The problem comes with TX. The very first TX you make gets correct power output, and contacts! BUT, the second and subsequent transmissions do not appear to have enough audio for the rig - I get a solid bar TX indicator on QMX on first TX but only two dots for TX on transmissions 2+.

The only way to correct this is to power cycle QMX, but then the same problem appears all over again - first transmission OK, subsequent ones not. I have read the manual concerning the two dots indicating insufficient audio from the computer (phone in my case). I have:

1. Set FT8CN to max volume out
2. Turned up the volume switches on the side of the phone to max
3. Set all the audio sliders in the Android settings audio window to max.
4. Assured myself there is nowhere else on the phone I can adjust volume output

But the problem persists.

The QMX manual says this:

"TX status is two dots: This means that QMX has been put into transmit mode via an appropriate CAT command, and that it is receiving audio from the PC; however the audio level is too low, so there is no RF.

Remember that there is a “Rise Threshold” setting in the QDX Configuration terminal application, which defaults to 80% of maximum value. If the amplitude of the audio sinewave coming from the PC is less than 80%, key-down will never be triggered."

I am tempted to adjust this rise threshold figure on the rig via Putty to below 80% and see what happens, but I am loving the rig and don't want to have an unfortunate unintended consequence!!

Anyone seen this issue and solved it, before I try that, or know of a reason why trying that is a bad idea?!

Cheers,

Daimon.
G4USI

Hello Daimon

I had exactly the same with my Oppo Reno 4, I already posted it in other FT8CN topic.

I think it might be something with hearing protection functions of the phone.

Anyway the solution was to reduce rise threshold to 70%. I reduced also falling threshold by 10% just to have the same difference between them.
I was too lazy to test other values, the first checked works so I did not bother.

73
Pawe? SO8FM?

I forgot to mention, it was QDX in my case.

73 Pawe? SO8FM?

Thanks Pawel. Well since the post I have reduced the threshold as low as 50% with no joy. I also tried transmitting from the app disconnected from the QMX and the audio blew my head off on every transmission, so that works, although the QMX was off. So I am left scratching my head currently. Will try to reduce threshold further still but not convinced I should need to. It must be a phone issue but the question is can it be fixed? I will try my Samsung tablet on Android and see if that works, but I really want the mobile phone solution!

Thanks for taking the time to reply.

Hi Daimon,

I also have a Google Pixel 6A and I see exactly the same behavior.
The strange thing is that just a few days ago it was working fine and I completed a QSO.
Now only the first transmission is actually sent.
I hope we (or the FT8CN author) can figure out a solution.

73, Mike KK7ER

OK Mike, let us keep each other (and others) posted here. I am away for a few days now but gonna try my android tablet when I get back. I have even been into develop options on the pixel but no luck

Cross posting from the FT8CN Issues forum:

I tested FT8CN 0.90 on a Google Pixel 6A and a QDX transceiver and it works fine.
I tested FT8CN 0.90 on a Google Pixel 6a and a QMX transceiver and it exhibits the problem.
I tested FT8CN 0.90 on a Samsung Galaxy A03s and a QDX transceiver and it works fine.
I tested FT8CN 0.90 on a Samsung Galaxy A03s and a QMX transceiver and it exhibits the problem.

So... it looks like a QMX issue.

73, Mike KK7ER

BTW, here's the link:??

73, Mike KK7ER

I just upgraded my QDX from 1.09 to 1.10 version and I have noticed I need to further reduce rise level below 70% (I set 60%) to have proper transmission.

So on the one side QDX/QMX behaviour may differ but also the radio SW version may have impact here. Unless my observation was some kind of weird coincidence...

73
Pawe? SO8FM

Hi Pawel,

I have never had to adjust the threshold on any of the QDX transceivers I have built (I only run FT8).
The one I was testing below was running 1.10 firmware.
This problem is very puzzling.
The audio stream is completely digital and gain is set to full scale (according to the slider positions).
For me, at least, it only occurs with the combination of QMX/FT8CN.
QMX/WSJT-X works fine.

73, Mike KK7ER

Hi Mike,

Same for me, happy WSJT-X user with two QDXes.
But I have started to use FT8CN with Oppo Reno 4 smartphone...
To have good TX I needed to reduce rise threshold to 70%. I made dozen of contact with that setting. Few days later I updated to 1.10 (it was 1.09 before) and to have proper TX I was forced to reduce the threshold by another 10%. Of course all system or app audio set to 100%.

I am not saying it is QDX, it may be the phone glitch. But the coincidence with software update is weird.

73
Pawe? SO8FM

Same issue here with QMX V 1.00.09 and FT8cn 0.90 running on Samsung XCover 4. I tried also older verion FT8CN 0.87 with the same result. The audio is there indicated with a solid line under A for the very first transmission and then there is no audio indicated with two dots below A when in transmit.

Same here too. The phone is a OnePlus 9 PRO. I tried several different audio settings, with the same result, first TX with RF out, second and subsequent periods no RF.?
A friend of mine has the same problem with his QMX. He tried his? with several different android phones and tablets with no luck. The only common factor being that I built both QMXs, at least that doesn't appear to be the issue.
Any ideas welcome.
73
Colin

I'm away from my QMX for a few days. I wonder if someone could try reverting to firmware 1.0.6 as mentioned here?/g/QRPLabs/topic/100771166?p=Created,,,20,2,0,0

The author of that thread claims that Fldigi worked until he updated the firmware from 1.0.6. Then it started losing audio on the second transmission. Sounds like our issue.?

73, Mike KK7ER?

Did anyone already find a solution for the problem with FT8CN?

Sometimes the first transmission works, often even not the first one.
The QMX just shows two Dots, as a sign of not enough signal and no tx signal at QMX.
Changing the Riese Threshold did not change the behaviour...

With WSJTx on Windows it is more reliable as long as you have the "Power Slider" on 100%, otherwise same situation with the two dots and no transmission

Hans, small update after upgrade to 1_00_010 that might help to debug the issue.

Transmitting to a dummy load, FT8CN connected via USB cable to QMX, SWR protection disabled.

1. The very first transmission works ok. QMX shows zero SWR bars and about 4W of output power. There is full bar under A indicating good audio level. The output power is confirmed by an external power meter.

2. All following transmissions: Two dots below A, no output power measured by external RF power meter and QMX indicates no output power as expected. However, what is very surprising, QMX show SWR bars! And the reading jumps between full scale (3 full bars) and about one half of the first bar. Very strange.

Then I have noticed, if I change teh QMX mode to CW and back do DiGi while the FT8CN is in receive period, the very next transmission goes out ok. So something internal to QMX code gets reset. Would you be able to investigate and fix this please?

While I had the same behavior on my first test about a week ago (with .9 fw), it worked just fine when I just retried with version .10 for two QSOs with FT8cn (ignoring that it constantly runs into protection with max SWR set to 3 and only showing SWR of about 1.2, also confirmed by the SWR meter in the tuner)
73 de OE6HKE

Harald, I turned ON SWR to repeat your test but with dummy load.

After each transmission the SWR protection kicked in (not sure why when SWR showed zero during the transmission) and I had to reset it by entering menu and exiting it. The next transmission went out ok though but the SWR kicked in again at the end.

To me, it looks like that clearing the SWR protection by entering menu and exiting it "resets" the same QMX software thing as changing mode to CW and back to Digi.?

I am being curious what this thing is.

@Peter right, I was entering and leaving the menu after each transmission to reset the "S" lock.

One more thing. If I don't clear the SWR protection and keep the S displayed, the next transmission from FT8cn show low audio (two dots under A).

I reckon the double dot in this very case is not an indication of a low audio coming from FT8cn but of a tripped PA protection.