tinymodem::QPSKCode Class Reference

Rate 1/2 convolutional code with K=5 (polynomials 0x17 and 0x19) of QPSK31 (fldigi) and a soft decision Viterbi decoder. More...

#include <PSK.h>

Public Member Functions
int	encode (int bit)
	Encodes one bit: returns the 2 bit symbol.
void	reset ()
	Resets the encoder and decoder state.
int	decode (const float metric[4])
template<class F>
void	flush (F on_bit)
	Provides the bits which are still in the decoder (oldest first).

Static Public Member Functions
static int	output (int reg)
	encoder output (2 bits) for the register of the last K input bits

Static Public Attributes
static constexpr int	K = 5
static constexpr int	STATES = 1 << (K - 1)
static constexpr int	DEPTH = 32
	decisions which are kept for the trace back (decoding delay in bits)

Protected Member Functions
int	traceBack (int depth)
	Input bit of depth steps ago on the best path.

Static Protected Member Functions
static int	parity (int v)

Protected Attributes
int	shreg = 0
float	metrics [STATES] = {0}
uint16_t	history [DEPTH]
int	pos = 0
int	count = 0

Detailed Description

Rate 1/2 convolutional code with K=5 (polynomials 0x17 and 0x19) of QPSK31 (fldigi) and a soft decision Viterbi decoder.

Copyright

GPLv3

Member Function Documentation

decode()

int tinymodem::QPSKCode::decode ( const float metric[4] )

inline

Adds the metrics of the 4 possible symbols (higher = more likely): returns the decoded bit of DEPTH steps ago or -1

encode()

int tinymodem::QPSKCode::encode ( int bit )

inline

Encodes one bit: returns the 2 bit symbol.

flush()

template<class F>

void tinymodem::QPSKCode::flush ( F on_bit )

inline

Provides the bits which are still in the decoder (oldest first).

output()

int tinymodem::QPSKCode::output ( int reg )

inlinestatic

encoder output (2 bits) for the register of the last K input bits

parity()

int tinymodem::QPSKCode::parity ( int v )

inlinestaticprotected

reset()

void tinymodem::QPSKCode::reset ( )

inline

Resets the encoder and decoder state.

traceBack()

int tinymodem::QPSKCode::traceBack ( int depth )

inlineprotected

Input bit of depth steps ago on the best path.

Member Data Documentation

count

int tinymodem::QPSKCode::count = 0

protected

DEPTH

int tinymodem::QPSKCode::DEPTH = 32

staticconstexpr

decisions which are kept for the trace back (decoding delay in bits)

history

uint16_t tinymodem::QPSKCode::history[DEPTH]

protected

K

int tinymodem::QPSKCode::K = 5

staticconstexpr

metrics

float tinymodem::QPSKCode::metrics[STATES] = {0}

protected

pos

int tinymodem::QPSKCode::pos = 0

protected

shreg

int tinymodem::QPSKCode::shreg = 0

protected

STATES

int tinymodem::QPSKCode::STATES = 1 << (K - 1)

staticconstexpr

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The documentation for this class was generated from the following file:

• src/modem/PSK.h