Mode-S CRC Checker

A CRC implementation for ADS-B Mode-S messages

Installation

$ npm install --save modes-crc

Documentation

Checker

• checksum
• crc

Fixer

• fix

Checker

### checksum(data, [bits])

Calculates the checksum of the data frame passed to it, based on the parity table provided.

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### crc(data, [bits])

Extracts the CRC value from a data frame last 3 bytes.

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Fixer

### fix(data, [bits])

Tries to fix a single bit on a message by transversing it and xor'ing each bit and comparing that new message checksum with the original CRC value.

Quick Examples

Pass it a buffer to the actual ADSB packet and the number of bits in the packet.

var checker = require('modes-crc')

var data = [93, 77, 32, 35, 122, 85, 166]

var packetChecksum = checker.checksum(data, checker.MODES_SHORT_MSG)

It will do a parity check and output a checksum that should be equal to the result of the packet CRC obtained by

var checker = require('modes-crc')

var data = [93, 77, 32, 35, 122, 85, 166]

var packetCrc = checker.crc(data, checker.MODES_SHORT_MSG)

Credits

A port of antirez's dump1090, but in Node.js: https://github.com/antirez/dump1090/

License

Keeps the 3-Clause BSD License from the "parent" repository