EPIRB RX (Emergency Position‐Indicating Radio Beacon Receiver)

EPIRB RX decodes 406 MHz distress beacon transmissions from EPIRBs (Emergency Position-Indicating Radio Beacons), PLBs (Personal Locator Beacons), and ELTs (Emergency Locator Transmitters). Received beacons are displayed in a scrolling console with beacon type, location (if encoded), and packet status. Up to 50 beacons are kept in memory at a time.

Received beacons are decoded using BCH error detection and single-bit correction. Each entry in the console is colour-coded: green = valid packet, yellow = corrected (1-bit error fixed), red = uncorrectable error.

Settings

• Freq: Selectable from a fixed list:
  • 406.028 MHz (default — primary Cospas-Sarsat frequency)
  • 406.025 MHz
  • 406.037 MHz
  • 433.025 MHz
  • 144.875 MHz
• RF Amp (0 or 1): Enabled by default on launch.
• LNA gain (0–40): Default 32.
• VGA gain (0–62): Default 32.

Decoded Beacon Fields

Tapping a beacon entry in the console opens a detail view showing:

• Beacon ID: Hexadecimal identifier encoded in the frame.
• Type: Beacon category — OLB (Orbiting Location Beacon), PLB (Personal Locator Beacon), ELT (Emergency Locator Transmitter), S-ELT (Serial ELT), N-ELT (National ELT), or Other.
• Emergency: Distress reason encoded in the message — Fire, Flooding, Collision, Grounding, Sinking, Disabled, Abandoning, Piracy, MOB (Man Overboard), or Other.
• Latitude / Longitude: GPS coordinates decoded from the frame, in decimal degrees. Shown as "Unknown" if no location data is present in the frame.
• Country: ITU country code (numeric) extracted from bits 1–10 of the frame.
• Time: RTC timestamp of when the packet was received.
• Status: Packet integrity result — OK, CORR (corrected, with error count), or ERR.

A See on map button in the detail view opens the map centred on the beacon's coordinates. The Map button on the main screen plots all received beacons that have valid location data.

Buttons

• Map: Opens the map view and plots all beacons with valid location data as markers. If no beacons with location data have been received, a dialog is shown.
• Clear: Clears the beacon list and resets all packet statistics (OK / CORR / ERR counters) to zero.
• Log / Stop: Toggles logging. When active, each decoded beacon is appended to LOGS/epirb_rx.txt as a CSV entry with timestamp, beacon ID, type, emergency type, coordinates, country code, packet status, and error count. Logging is active by default on launch.

Settings Persistence

App settings (frequency selection, gain) are saved to rx_epirb.ini when App Settings is enabled in the global Settings menu.