Signal and protocol guide ยท 2.0
Which signal is on the receiver?
A picture format, a radio waveform and an SDR connection describe different parts of the same receiving chain. Version 2.0 adds digital packet reception, radio facsimile and DRM alongside the existing analog SSTV library.
Signal family comparison
| Family | What carries the picture | Receiver input | Identification and recovery | Reference |
|---|---|---|---|---|
| Analog SSTV | Raster lines represented by audio-frequency tones | Radio audio, microphone, file replay, or demodulated SDR I/Q | VIS or family-specific start sequence; line synchronization, tone-to-pixel mapping and slant correction | Analog mode tables |
| SSDV | JPEG fragments in image packets | Supported AFSK/FSK/BPSK link or I/Q profile | Recover link frames first; validate packet identity and CRC/FEC; reconstruct JPEG MCUs | SSDV link profiles |
| Weather Fax | A continuous monochrome scan at a configured line rate | USB/LSB receiver audio or file replay | Choose LPM and IOC; align the scan and correct polarity/slant | Weather Fax reference |
| DRM A-D | Digital services in a DRM30 OFDM multiplex; MOT for images | Wide enough SDR channel, or 48 kHz real IF centred at 12 kHz | Synchronization, FAC, SDC, MSC, then application-object recovery | DRM A-D tables |
| DRM E | DRM+ VHF OFDM multiplex; MOT for images | 192 kHz complex I/Q, two independent channels | Mode E acquisition and control-channel decode before service/object recovery | DRM Mode E |
Supported SSDV receiving profiles
The 2.0 receiver offers automatic selection and manual profiles for 1200 AFSK/AX.25, 9600 FSK/AX.25, 9600 GFSK/AX.25, 1200 BPSK/AO-40, IL2P, Slow FSK/SSDV, SatNOGS IQ and Doppler search. The final two are input/search routes rather than new packet formats.
Read the profile table, framing details and limitations. KISS/AX.25 exists in the shared codec library but is not a selectable network input in the 2.0 app; do not confuse it with the app's SDR network sources.
Network protocols are receiver inputs
rtl_tcp, SoapyRemote and SDR++ move samples and tuner commands between a radio server and the app. They do not decide whether the received transmission is SSTV, SSDV, Weather Fax or DRM. Choose the source connection and then the signal family.
Compare platform support, ports and sample formats.
What the samples establish
The library contains complete SSDV image examples, separate transport/telemetry fixtures, DRM A-E image waveforms and six Weather Fax line-rate strips. Each download states what it carries. A generated clean waveform exercises a documented format; it does not establish reception of every transmitter or every propagation condition.