guides:apx
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APX
APX is an experimental binary packet format for transmitting location information from a payload.
Packet Format
| Offset | Name | Size | Description |
|---|---|---|---|
| 0 | Callsign | 6 | Callsign of the user / payload. The format is described below |
| 6 | Timestamp | 5 | UTC timestamp |
| 11 | Latitude | 4 | Latitude (-90 - 90 degrees) (0.000000042 degree accuracy, or ~0.46cm accuracy) |
| 15 | Longitude | 4 | Longitude (-180 - 180 degrees) (0.000000084 degree accuracy, or ~0.93cm accuracy at the equator) |
| 19 | Altitude | 3 | Altitude (-100000 - 100000 metres) |
| 22 | Fix Status | 1 | 0 = No Fix, 1 = Fix, >= 2 undefined |
| 23 | Satellites | 1 | Number of satellites visible |
| 24 | User data | 4 | 32-bit user data |
| 28 | CRC | 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.1321645946.txt.gz · Last modified: 2011/11/18 19:52 by fsphil