p25p1_hdu.h File Reference

#include "p25p1_heuristics.h"

Go to the source code of this file.

Functions
int	read_dibit (dsd_opts *opts, dsd_state *state, char *output, int *status_count, int *analog_signal, int *did_read_status)
void	read_dibit_update_analog_data (dsd_opts *opts, dsd_state *state, char *buffer, unsigned int count, int *status_count, AnalogSignal *analog_signal_array, int *analog_signal_index)
void	read_word (dsd_opts *opts, dsd_state *state, char *word, unsigned int length, int *status_count, AnalogSignal *analog_signal_array, int *analog_signal_index)
void	read_hamm_parity (dsd_opts *opts, dsd_state *state, char *parity, int *status_count, AnalogSignal *analog_signal_array, int *analog_signal_index)
void	read_golay24_parity (dsd_opts *opts, dsd_state *state, char *parity, int *status_count, AnalogSignal *analog_signal_array, int *analog_signal_index)
void	read_zeros (dsd_opts *opts, dsd_state *state, AnalogSignal *analog_signal_array, unsigned int length, int *status_count, int new_sequence)

Function Documentation

read_dibit()

int read_dibit	(	dsd_opts *	opts,
		dsd_state *	state,
		char *	output,
		int *	status_count,
		int *	analog_signal,
		int *	did_read_status )

Reads a dibit (two bits) from the stream of data. Takes into account the periodic occurrence of status bits that show up every 36 dibits. Status bits are discarded.

Parameters

opts	A pointer the the DSD options.
state	A pointer the the DSD state structure.
output	A pointer to be filled with the dibit read. Two bytes used for each dibit.
status_count	Variable used to keep track of the status symbols in the dibit stream. There is one status every 36 dibits. With this counter we can skip the status.
analog_signal	A pointer with the actual analog value read from the input signal and that has been interpreted as the dibit we are returning in output.
did_read_status	Address were a boolean is returned. This is set to true when one status symbol was read (and skipped). This indicates that the sequence on dibits has been broken and is used by the P25 heuristics.

read_dibit_update_analog_data()

void read_dibit_update_analog_data	(	dsd_opts *	opts,
		dsd_state *	state,
		char *	buffer,
		unsigned int	count,
		int *	status_count,
		AnalogSignal *	analog_signal_array,
		int *	analog_signal_index )

Reads a number of dibits and stores its value together with the actual analog value that has been intrepreted as the dibit into an AnalogSignal structure. This is used later in the P25 heuristics module to improve the accuracy of the digitizer.

Parameters

opts	A pointer the the DSD options.
state	A pointer the the DSD state structure.
output	A pointer to be filled with the dibits read.
count	The number of bits to read (remember: 1 dibit = 2 bits).
status_count	Variable used to keep track of the status symbols in the dibit stream. There is one status every 36 dibits. With this counter we can skip the status.
analog_signal_array	The pointer to the start of a sequence of AnalogSignal structures. The information is updated for each dibit read.
analog_signal_index	The actual index into the AnalogSignal array. This is increased here wich each dibit read.

read_golay24_parity()

void read_golay24_parity	(	dsd_opts *	opts,
		dsd_state *	state,
		char *	parity,
		int *	status_count,
		AnalogSignal *	analog_signal_array,
		int *	analog_signal_index )

Reads 12 bits from the stream of data. Those are the extended Golay parity bits that follow a word of data.

read_hamm_parity()

void read_hamm_parity	(	dsd_opts *	opts,
		dsd_state *	state,
		char *	parity,
		int *	status_count,
		AnalogSignal *	analog_signal_array,
		int *	analog_signal_index )

Reads 4 bits from the stream of data. Those are the parity bits that follow each hex word.

read_word()

void read_word	(	dsd_opts *	opts,
		dsd_state *	state,
		char *	word,
		unsigned int	length,
		int *	status_count,
		AnalogSignal *	analog_signal_array,
		int *	analog_signal_index )

Reads a word, made up of length bits or length/2 dibits. Also keeps track of the status dibits.

read_zeros()

void read_zeros	(	dsd_opts *	opts,
		dsd_state *	state,
		AnalogSignal *	analog_signal_array,
		unsigned int	length,
		int *	status_count,
		int	new_sequence )

Reads bits from the data stream that should all be zeros. This is valuable information for the heuristics module and we update it.

Parameters

opts	A pointer the the DSD options.
state	A pointer the the DSD state structure.
analog_signal_array	The pointer to the start of a sequence of AnalogSignal structures.
length	Number of bits to read.
status_count	Variable used to keep track of the status symbols in the dibit stream.
new_sequence	Bool used to update the sequence_broken value of the first AnalogSignal element.