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Communications Modes

FBSAT59 includes a full suite of digital communication decoders and encoders for amateur satellite modes.

Overview

Open each decoder from the Communications menu (between Radio and Autotrack/Record). Each opens as its own tab with a × to close it.

Menu item Purpose Input
APRS Position beacons & messaging (Bell 202 AFSK, incl. 9k6 G3RUH) SDR or rig audio
Telemetry Satellite housekeeping frames SDR or rig audio
SSTV / SSDV Image reception SDR or rig audio
FT4 Weak-signal digital QSOs SDR or rig audio
Q65 EME / weak-signal QSOs SDR or rig audio
CW Decoder Morse decoding (ML model) SDR or rig audio
AX100 Digi AX.100 / Mobitex digipeater telemetry SDR or rig audio
METEOR / HRPT Weather-satellite imagery via SatDump SDR

APRS (Automatic Packet Reporting System)

Receive amateur radio position reports and telemetry from satellites.

Receiving APRS

  1. Communications → APRS
  2. Select a satellite (ISS, JO-97, etc.)
  3. View received packets in real-time
  4. Received positions appear as cyan ▲ pins on the Dashboard map

APRS Data Captured

  • Callsign and SSID
  • Latitude / Longitude
  • Altitude, speed, heading
  • Comment text

Transmitting APRS

Send position beacons or messages:

  1. Set your callsign in File → Set QTH… (the Station field)
  2. Click [Transmit Position]
  3. Radio PTT activates automatically
  4. Position beacon sent via AFSK modulation

Telemetry

Decode binary telemetry frames from amateur satellites.

Two Receive Modes

Bell 202 AFSK (Built-in)

1200 baud Bell 202 demodulator: - Works with SDR or rig audio - Supports 12+ satellites with built-in format definitions (ISS, JO-97, RS-44, etc.) - Raw hex display for unlisted satellites

gr-satellites (Optional)

Advanced demodulator supporting 300+ satellites: - Install via Help → gr-satellites Installation… - Automatic format detection - Full telemetry parsing

Satellite Telemetry

Typical decoded data: - Battery voltage - Temperature readings - Solar panel current - Transmitter status - Beacon counter

SSTV / SSDV (Image Reception)

Receive images transmitted by amateur satellites.

Supported formats

  • SSTV: Robot36 and PD120 (auto-detected from the line timing) — the two modes used for amateur-satellite SSTV
  • SSDV: packetised image transmission

How to receive

  1. Communications → SSTV / SSDV
  2. Tune to the satellite's image transmitter (e.g. ISS SSTV events on 145.800 MHz FM)
  3. The image builds line by line as it is received

FT4 (Weak-Signal Digital)

Encode/decode FT4, a digital mode for satellite QSOs.

Decoding

  1. Tune radio to satellite FT4 downlink frequency
  2. Communications → FT4
  3. Decoded messages appear in real-time

Transmitting FT4

  1. Set radio to uplink frequency
  2. Select your callsign and message
  3. Click [Transmit]
  4. Radio PTT activates automatically
  5. QSO logged (ADIF export available)

Supported satellites: RS-44, JO-97, MO-122, others

Q65 (EME / Moonbounce)

Earth-Moon-Earth weak-signal mode for long-distance satellite QSOs.

Unique Features

  • Ultra-weak-signal reception capability
  • Doppler freeze during transmission (prevents frequency drift)
  • QSO state machine (IDLE → CALLING → EXCHANGE → CONFIRM → LOGGED)
  • Submodes A–E with periods 15/30/60 seconds

Operation

  1. Communications → Q65
  2. Tune to satellite EME downlink
  3. Select submode and period
  4. Monitor signal strength & status
  5. Transmit when ready

Note: Q65 requires significant antenna gain and clear path to moon. Research EME before attempting.

CW Decoder (AI-Powered)

Automatic Morse code detection using deep learning.

Features

  • Recognizes CW/CW-R transmissions automatically
  • Works with both SDR and rig audio
  • Real-time decoding (20-second rolling buffer)
  • Supports typical satellite CW speeds (10–30 WPM)

How to Use

  1. Communications → CW Decoder
  2. Tune radio to CW downlink
  3. Watch decoded text appear in real-time

Installation: - First use downloads ONNX model automatically - ~15 MB download (one-time)

Optional libraries

Some modes need a helper the installer doesn't bundle. Each has an entry in the Help menu that detects, downloads and installs it:

Help menu item Needed for
Direwolf Installation… APRS / telemetry via rig audio (external AFSK modem)
gr-satellites Installation… Advanced telemetry (300+ formats)
ft8lib Installation… FT4 decoding
FT4 Enhanced Decoder Installation… WSJT-X-based FT4 decoder
Q65 Library Installation… Q65 decoding (the TX encoder is pure Python and needs nothing)
CW Model Installation… CW Decoder ML model
SatDump… METEOR / HRPT imagery
SDR Device Installation… SoapySDR drivers for your SDR

UDP log broadcast

FBSAT59 can send every confirmed digital-mode contact to another logger as an ADIF record over UDP:

  1. File → General Settings → Logging
  2. Tick Broadcast logged QSOs via UDP (ADIF)
  3. Set Host and Port (default 2333) — e.g. Wavelog or GridTracker on your LAN

See Configuration — Logging.

Next Steps