Module convolutional 

Convolutional code (rate 1/2, K=7) with Viterbi decoding (CCSDS 131.0-B-5). CCSDS Convolutional Code (Rate 1/2, K=7) with Viterbi Decoding

Implements the convolutional code specified in CCSDS 131.0-B-5 (TM Synchronization and Channel Coding).

Parameters

• Constraint length: K = 7 (64 encoder states)
• Code rate: 1/2 (2 output symbols per input bit)
• Generator polynomials: G1 = 171₈ (0x79), G2 = 133₈ (0x5B)
• Tail: K−1 = 6 zero bits flush the encoder to state 0

Encoding

Each input bit plus the 6-bit shift register state produces two coded symbols (G1 first, then G2). After all data bits, six zero tail bits terminate the trellis at state 0.

Decoding

Soft-decision Viterbi algorithm with i16 LLR inputs (positive means bit 0 is more likely), matching the LDPC decoder convention. Uses a sliding-window traceback (depth 5K = 35) to bound stack usage regardless of frame length.

Structs

ConvolutionalEncoder

Convolutional encoder implementing FecEncoder.

ViterbiDecoder

Hard-decision Viterbi decoder implementing FecDecoder.

Enums

ConvError

Errors from convolutional coding operations.

Constants

K

Constraint length.

Functions

decode

Decodes a convolutionally coded frame using soft-decision Viterbi.

encode

Encodes data using the rate-1/2, K=7 convolutional code.

encoded_len

Returns the number of encoded bytes for data_len data bytes.

hard_to_llr

Converts hard bits (packed bytes, MSB-first) to LLR values.