frequency stability of the SR105U

[pacrunner]

I have noticed that when I look at the signals on webSDR on FIAB4, they are all about 434.8840 kHz. this could be why I can see a carrier, but no audio and QSSTV can hear the RF but does not display anything.

How is the radio unit tuned, i have looked at the software and it is set to 434.9000 kHz.
Is there any offset in the programming?
Anyone any ideas, what i have noticed is the 5v rail is at 4.3v. The voltage leaving the battery board is 4.6v.

[alanbjohnston]

Can you post the output of this command (or a screenshot photo)

CubeSatSim/config

When you run QSSTV, one of the options is to choose another frequency. You could type in 4348840 and see if it decides.

Alan

[pacrunner]

had another very close look at the main board, and found a few dry joints on the SMD components. I have soldered these.
I have now run the main board test again, and when I do the 'complete Payload Test' I am not seeing any data in APRS mode, there is plenty of RF and it appears to be on 434.900KHz. When I switch to DUV/FSK mode the system reboots, after the reboot I can see all the payload data ok. The only fail is the I2C bus 3. I get the same results using BPSK.
It appears to me to be software related, as there is no modulation on the FM carrier.
Could you tell me which software version should be on the card. I have 2 cards on with an image and the other programmed using the 'Installation Script Option Steps' Only mine does not prompt me for my callsign. I am using 32Gb micro sd cards. The image is downloaded from the URL, so as to take out the download step.
Any help will be appreciated.

[alanbjohnston]

Can you post the results of this command:

CubeSatSim/config

And

CubeSatSim/log

And

CubeSatSim/log -t

I’ll take a look and see what the logs show.

Alan

[pacrunner]

Attached are the printouts you asked for.
Below are the actions/commands/results:

• Start up - Morse Id ok
• 2 bursts of carrier then BSPK data all received and decoded by Foxtelem
• Changed mode using SSH to APRS
• Software rebooted, Morse id ok
• Carrier no modulation
• Changed to CW , software restarted.
• Carrie no modulation
• Closed down using button.

This may help.
log.txt
logt.txt

[alanbjohnston]

Thanks for sharing the log files.

I see the error messages relating to the I2C Bus 3. The I2C Bus 1 also doesn't seem to be working. I suspect that in FSK or BPSK mode, in FoxTelem, you get all zeros for all the solar panels and battery voltages and currents. To troubleshoot this, I'd suggest unplugging the Solar Board and see if FoxTelem shows at least the Battery voltage. You should inspect the Solar Board to make sure all the jumpers A0 and A1 are set correctly as shown in https://github.com/alanbjohnston/CubeSatSim/wiki/6.-Solar-Board You also might have some bridged solar joints or unsoldered pins as well.

You can try this command: CubeSatSim/config -S and you if everything was working on your I2C busses, you should see several I2C devices at addresses 40, 41, 44, and 45 on Bus 1 and 3 like this:

   CubeSatSim v2.2 configuration tool
    
   Scan both I2C buses on the Raspberry Pi
   
   I2C Bus 1
    
        0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
   00:                         -- -- -- -- -- -- -- -- 
   10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   40: 40 41 -- -- 44 -- -- -- -- -- -- -- -- -- -- -- 
   50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   70: -- -- -- -- -- -- -- --                         
    
   I2C Bus 1
    
        0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
   00:                         -- -- -- -- -- -- -- -- 
   10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   40: 40 41 -- -- 44 45 -- -- -- -- -- -- -- -- -- -- 
   50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
   70: -- -- -- -- -- -- -- --    

But I suspect that you will only see -- indicating no voltage and current sensors are available.

As for the APRS and CW modes, I don't see anything wrong in the logs. I think you are seeing a carrier signal at 434.9 and the blue LED lighting up at the right moment, but no signal. This is most likely due to a hardware problem in the Audio Low Pass Filter circuit on the Main board:

You could check to make sure the parts R20, R19, C5, and C6 are soldered in correctly and not bridged (the parts labeled DNI are the surface mount part that shouldn't be installed on your PCB).

There is also a chance that you have a bad Raspberry Pi Zero 2W. If you had another Pi Zero 2W, you could try swapping it. But it is most likely a problem on your Main board.

There is a possible workaround if you can't get your Audio Low Pass Filter working. You could use an extra audio jumper and install J14 and then make an edit to the transmit.py code to get it working - I can provide full details if we can't get this resolved.

Alan

[pacrunner]

Alan,I thought it was to do with the main board, so I was doing the testing in the main board 2 instructions.Found a dry/poor joint on the SR105U pin 8 the audio input.  It's the first time I have done any SMT work, and was using a stardard soldering iron.  It appears to be running ok.  I have run all the final tests all ok.Thanks for your help and patience.Tim Stanley G4TXK Sent from Outlook for AndroidFrom: Alan Johnston ***@***.***>Sent: Wednesday, July 15, 2026 1:30:55 amTo: alanbjohnston/CubeSatSim ***@***.***>Cc: pacrunner ***@***.***>; Author ***@***.***>Subject: Re: [alanbjohnston/CubeSatSim] frequency stability of the SR105U (Discussion #435)Thanks for sharing the log files.I see the error messages relating to the I2C Bus 3. The I2C Bus 1 also doesn't seem to be working. I suspect that in FSK or BPSK mode, in FoxTelem, you get all zeros for all the solar panels and battery voltages and currents. To troubleshoot this, I'd suggest unplugging the Solar Board and see if FoxTelem shows at least the Battery voltage. You should inspect the Solar Board to make sure all the jumpers A0 and A1 are set correctly as shown in https://github.com/alanbjohnston/CubeSatSim/wiki/6.-Solar-Board You also might have some bridged solar joints or unsoldered pins as well.You can try this command: CubeSatSim/config -S and you if everything was working on your I2C busses, you should see several I2C devices at addresses 40, 41, 44, and 45 on Bus 1 and 3 like this: CubeSatSim v2.2 configuration tool Scan both I2C buses on the Raspberry Pi I2C Bus 1 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: 40 41 -- -- 44 -- -- -- -- -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- -- I2C Bus 1 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: 40 41 -- -- 44 45 -- -- -- -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- -- But I suspect that you will only see -- indicating no voltage and current sensors are available.As for the APRS and CW modes, I don't see anything wrong in the logs. I think you are seeing a carrier signal at 434.9 and the blue LED lighting up at the right moment, but no signal. This is most likely due to a hardware problem in the Audio Low Pass Filter circuit on the Main board:image.png (view on web) You could check to make sure the parts R20, R21, C5, and C8 are soldered in correctly and not bridged (the parts labeled DNI are the surface mount part that shouldn't be installed on your PCB).There is also a chance that you have a bad Raspberry Pi Zero 2W. If you had another Pi Zero 2W, you could try swapping it. But it is most likely a problem on your Main board.There is a possible workaround if you can't get your Audio Low Pass Filter working. You could use an extra audio jumper and install J14 and then make an edit to the transmit.py code to get it working - I can provide full details if we can't get this resolved.Alan—Reply to this email directly, view it on GitHub, or unsubscribe.Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS and Android. Download it today! You are receiving this because you authored the thread.