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Ian Gulliver
2016-02-13 23:14:36 +00:00
parent 0b3deee0ca
commit bb657cf459
1 changed files with 10 additions and 10 deletions
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protocols/beast.md
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@@ -19,32 +19,32 @@ Escaping makes frame length for a given type variable, up to
## Frame structure
* `0x1a`
* Frame type (see types below)
* 1 byte frame type (see types below)
* 6 byte MLAT timestamp (see below)
## Frame types
* 0x31: Mode-AC frame
* `0x31`: Mode-AC frame
* 1 byte signal level (TODO: units?)
* 2 byte Mode-AC data
* 0x32: Mode-S short frame
* `0x32`: Mode-S short frame
* 1 byte signal level (TODO: units?)
* 7 byte Mode-S short data
* 0x33: Mode-S long frame
* `0x33`: Mode-S long frame
* 1 byte signal level (TODO: units?)
* 14 byte Mode-S long data
* 0x34: Status data
* `0x34`: Status data
* *Appears to only be used by Mode-S Beast hardware later versions*
* ?? byte status data
* ?? byte DIP switch configuration
## MLAT timestamp
The MLAT timestamp included in each frame is the value of a 12 MHz counter at
the of packet reception. This counter isn't calibrated to external time, but
receiving software can calculate its offset from other receiving stations
across multiple packets, and then use the differences between station receive
timing to calculate signal source position.
The MLAT timestamp included in each frame is the big-endian value of a 12 MHz
counter at the time of packet reception. This counter isn't calibrated to
external time, but receiving software can calculate its offset from other
receiving stations across multiple packets, and then use the differences between
station receive timing to calculate signal source position.
## Implementations