Official wiki: https://wiki.amsat-dl.org/doku.php?id=en:hsmodem:start

Official Windows setup instructions: https://wiki.amsat-dl.org/doku.php?id=en:hsmodem:installwin

The official download has no PTT support, use M0LTE's fork with PTT support: https://github.com/M0LTE/AMSAT-DL-QO-100-Modem/releases

If a message about missing DLLs appears when the program starts (msvcp140.dll and others), the Microsoft package: vc_redist.x86.exe must be installed. Please only use the original from Microsoft, this is located here: https://support.microsoft.com/de-de/help/2977003/the-latest-supported-visual-c-downloads

ATTENTION: ALWAYS select the x86 version (vc_redist.x86.exe) even if you have a 64bit PC!

Download and extract the ZIP somewhere if using M0LTE's fork, otherwise run the installer

Run oscardata.exe (you might need to install .NET Framework if you don't have it already)

After the first start, Windows 10 shows two dialogs to obtain permission for network access. You have to confirm both, otherwise the program won't run.

Go to Rig Control tab

Install Hamlib if it says it is necessary, link is in the tab

Choose your radio, enter your COM port into the Device box, e.g. COM12, choose your speed if needed

Click Save

Go to the Setup tab, set your callsign, name, location and locator.

Type some text in the Info box to overlay on images you send, e.g. CQ OARC

Select Insert Callsign into Picture, Insert Info into Picture

Do as you please with announcement before TX - it transmits a voice description of the mode - I have turned this off

Select your transceiver audio interfaces and levels, similar to WSJT-X etc.

Successful installation and functioning network access can be recognized in the status line by the network address of the modem being displayed.

This tab sends digital SSTV. The quality is pleasingly good.

Go to the Image tab, select a quality (approx. transmission duration) and an image resolution.

Click Load Image, select an image.

Select a speed in bits/sec. The modulation and audio bandwidth is also listed. The selection will need to be the same at both ends.

Click Send to key up and start sending the image. You'll need to tweak audio levels to not over / under-drive the rig- use the same techniques as any other data mode. Don't drive the rig hard.

Reception

I'll write more about reception when someone sends me something!

Use the FFT tuning window to align your radio tuning to the transmitting station. The cluster diagram to the left should show e.g. 4 clusters for QPSK when correctly tuned. When you are receiving frames successfully, RX Sync and RX Signal will be green.

The line at 100Hz in the tuning window is a tuning aid. This makes it very easy to find the exact frequency. In the spectrum display there is a red line at 100 Hz. You bring the 100 Hz peak to this line and the modem will synchronize immediately. A drift “after” locking is not a problem, it is not necessary to always follow the line.

The received, yellow 100 Hz peak should lie reasonably on the red 100 Hz line.