RECE-232

Recommended Error Correction Encoding (232)

RECE-232 is a data encoding scheme that encodes binary data to ASCII while maximizing error detection and correctability. It's intended for use in ASCII RS-232 streams where bitflips and dropped characters may be common.

Format

By default, the encoder will output bytes in ASCII range 32 through 127. This range consists of all printable characters, except for the non-printable DEL (127) character, which may be replaced with TAB (9). Newlines are recommended as a delimiter between messages.

A message contains a 6-bit header followed by one or more longwords (i.e. uint32 or float). The resultant ASCII length is equal to 3 + 8*N where N is the number of encoded longwords.

Example Encoder Output

Header	Longword 0	Longword 1	Longword 2	Length	Message Output
0x00	0x00000000	-	-	11 bytes	@ @ @ »2E2
0x1F	0x01234567	0x89ABCDEF	-	19 bytes	'k(_#I N/o9»+M1n1L'
0x3F	0xFFFFFFFF	0xFFFFFFFF	0xFFFFFFFF	27 bytes	?»?»?»?@?»?J?»?u?»?J?»?u y4

Performance

Example benchmark:

• 1-7 random longwords per message
• 0.1% chance of bit error per bit
• 0.25% chance of dropped byte per byte

Messages with generated errors:  29788492 / 100000000 (29.78849%)
Average message length: 35.00 bytes

Flipped bits:  27930063
Dropped bytes: 8753389

Recovered errors:     26708257 / 29788492 (89.65965%)
Unrecoverable errors:  3080234 / 29788492 (10.34035%)
Undetected errors:           1 / 29788492 (0.000003%)

Versions

• 0.1.0: Initial release with Java encoder/decoder and C encoder

• 0.1.1: Improved decoder success rates

• 0.2.0: Modified trailing checksum for better error detection rates (breaks compatibility)