guides:apx
APX
APX is an experimental binary packet format for transmitting location information from a payload.
Packet Format
| Offset | Name | Size | Description |
|---|---|---|---|
| 0 | Packet Type | 1 | 0x76 - Position |
| 1 | Callsign | 6 | Callsign of the user / payload. The format is described below |
| 7 | Timestamp | 5 | UTC timestamp |
| 12 | Latitude | 4 | Latitude (-90 - 90 degrees, 0.000000042 degree accuracy, or ~0.46cm accuracy) |
| 16 | Longitude | 4 | Longitude (-180 - 180 degrees, 0.000000084 degree accuracy, or ~0.93cm accuracy at the equator) |
| 20 | Altitude | 3 | Altitude (-8388608 - 8388607 cm, or -83.8 - 83.8 km, two's compliment) |
| 23 | Fix Status | 1 | 0 = No Fix, 1 = Fix, >= 2 undefined |
| 24 | PDOP | 1 | Positional dilution of precision |
| 25 | Heading | 1 | Heading (0 - 360 degrees, 1.4 degree accuracy) |
| 26 | Ground Speed | 1 | Ground speed (0-100 m/s, 0.39 m/s accuracy) |
| 27 | Vertical Speed | 1 | Vertical speed (0-100 m/s, 0.39 m/s accuracy) |
| 28 | Checksum | 4 | 32-bit CRC |
| 32 | FEC | 32 | Reed-Solomon forward error correction data. This may be omitted for storage, or if the mode already provides FEC |
Sizes and offsets are in bytes, with each packet being 64 bytes in total (or 32 bytes with no FEC data).
guides/apx.txt · Last modified: 2011/11/19 00:38 by fsphil