Modulation Parameters

• Center frequency: 434MHz

• Bandwidth: 62.5kHz

• Spreading factor: 12

• Coding Rate: 4/5

• Sync word: 0x12

Locations

FN20QN67 -13M HAAT 100mW

FN20SM45 43M HAAT 100mW

Packet Contents

General Format

All packets follow the general format with identical headers. The payload format is dependant on the packet type.

[callsign] [flags][pkt_counter][payload]

callsign: ASCII text (7-bit) for transmitter callsign (SSID supported)

flags: 1 byte (see mapping below))

pkt_counter: 8 bit unsigned integer

payload: type specific data

Flags

Bit 7: MUST be set to 1 (signals end of callsign)

Bit 6: ACK requested

Bit 5-0: packet type

Packet types:

0x00: beacon

0x01: positional telemetry report

0x02-0x3d: reserved

0x3e: APRS encapsulated

0x3f: reserved

Beacon

Send a simple beacon

Payload format:

Any ASCII text (suggest 8 character maidenhead grid location, HAAT, and power level)

Positional telemetry report

Send current position of the transmitter

Payload format:

[latitude][longitude]

Fields:

latitude: Degrees North * 10e7 as signed 32 bit integer sent in network byte order

longitude: Degrees East * 10e7 as signed 32 bit integer sent in network byte order