If you do not want to mess arround with PPM settings, buy a high quality dongle with fix PPM of 1.
- Start SDR Touch app and go to 162.025 MHz ( AIS Vessel Freq Chan B )
- Switch to Spectrum view and zoom in
- PPM setting is in SDR Touch not where you expect it.
Setting is under menu >>Gain<<
- Now see the result in the spectrum. So my dongle has got about 44 ppm
Use this PPM value in the AIS Share app.