Testing SSB USB signal source

Testing on Windows

Using recored IQ wav file + SDR# with USB demodulator

In this option your radio with SSB-USB demodulator will be mocked (replaced) with SDR# software. It has an option to play IQ file saved in wav file. Then, IQ signal can be demodulated using its SSB-USB demodulator - demodulated signal is pointed to your system sound card and should be similar to the output of your radio receiver. Then, audio stream from SDR# can be captured by SSB-USB signal source in HAM Desktop Software.

Step-by step instruction:

1. Download and install SRD# (SDRSharp) software - https://airspy.com/download/
2. Install VB-Cable (https://www.vb-audio.com/Cable/) - it's a virtual cable that connects your sound card output and input - so the audio form SDR# can be directed to virtual line in.
3. In Windows sound settings set virtual cable as playing and recording devices:
4. Download test IQ wav file
5. Open the file in SDR# using IQ File (*.wav) option and click play button:
6. PW-Sat2 frequency (435.275 MHz) is at -30 kHz frequency. Since typical SSB radio has a filter of about 4 kHz (or a bit wider) width, to catch all signal within the band we have to set center frequency of SDR#/radio about 2-3 kHz below PW-Sat2 center frequency. In this case we have to set SDR# center frequency at -33 kHz, because PW-Sat2 center frequency is at -30 kHz. Adjust window bandwidth to about 4 kHz.

7. Run PW-Sat2 HAM Desktop Software and choose SSB-USB audio in source - set proper frequency offset - in our case 3 kHz. Accept popup window by clicking OK.

8. Run Demodulator in HAM Desktop Software - you should be able to see decoded frames in Main window of the application. You can tune parameter in case of problems (offset, bandwidth).

Using demodulated (SSB-USB) audio file

Another option is to play attached audio file that should be similar to a signal from your TRX with SSB-USB demodulator enabled. Baud rate of the PW-Sat2 downlink was set to 1200 bps.

How we've created the audio file

Signal was demodulated using SDR# built-in USB demodulator (center frequency 3 kHz below PW-Sat2 center frequency, bandwidth 4 kHz). Settings are shown below:

Download audio file: 1200_bps_audio_ssb_usb_demodulated.wav

Parameters for Audio USB-SSB source (offset 3000 Hz):

Step-by-step instruction:

1. Install VB-Cable (https://www.vb-audio.com/Cable/) - it's a virtual cable that connects your sound card output and input - so the audio form SDR# can be directed to virtual line in. Of course you can use physical cable connecting your audio output and line-in in a sound card.
2. In Windows sound settings set virtual cable as playing and recording devices:
3. Download 1200_bps_audio_ssb_usb_demodulated.wav
4. Play the file by your favorite media player.
5. Run PW-Sat2 HAM Desktop Software and choose SSB-USB audio in source - set proper frequency offset - in our case 3 kHz. Accept popup window by clicking OK.

6. Run Demodulator in HAM Desktop Software - you should be able to see decoded frames in Main window of the application.

7. You should receive periodic message frames: