dds.c File Reference

#include <inttypes.h>
#include <math.h>
#include "spandsp/telephony.h"
#include "spandsp/dds.h"

Defines
#define	M_PI   3.14159265358979323846
#define	SLENK   7
#define	DDS_STEPS   (1 << SLENK)
#define	DDS_SHIFT   (32 - 2 - SLENK)
Functions
int32_t	dds_phase_step (float frequency)
	Find the phase step value to achieve a particular frequency.
int	dds_scaling_dbm0 (float level)
	Find the scaling factor needed to achieve a specified level in dBm0.
int	dds_scaling_dbov (float level)
int16_t	dds_lookup (uint32_t phase)
	Find the amplitude for a particular phase.
int16_t	dds_offset (uint32_t phase_acc, int32_t phase_offset)
	Find the amplitude for a particular phase offset from an accumulated phase.
int16_t	dds (uint32_t *phase_acc, int32_t phase_rate)
	Generate an integer tone sample.
int16_t	dds_mod (uint32_t *phase_acc, int32_t phase_rate, int scale, int32_t phase)
	Generate an integer tone sample, with modulation.
icomplex_t	dds_complex (uint32_t *phase_acc, int32_t phase_rate)
	Generate a complex integer tone sample.
icomplex_t	dds_mod_complex (uint32_t *phase_acc, int32_t phase_rate, int scale, int32_t phase)

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Detailed Description

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Function Documentation

int16_t dds	(	uint32_t *	phase_acc,
		int32_t	phase_rate
	)

Generate an integer tone sample.

Parameters:

	phase_acc	A pointer to a phase accumulator value.
	phase_rate	The phase increment to be applied.

Returns:

The signal amplitude, between -32767 and 32767.

icomplex_t dds_complex	(	uint32_t *	phase_acc,
		int32_t	phase_rate
	)

Generate a complex integer tone sample.

Parameters:

	phase_acc	A pointer to a phase accumulator value.
	phase_rate	The phase increment to be applied.

Returns:

The complex signal amplitude, between -32767 and 32767.

int16_t dds_lookup

(

uint32_t

phase

)

Find the amplitude for a particular phase.

Parameters:

phase

The desired phase 32 bit phase.

Returns:

The signal amplitude.

int16_t dds_mod	(	uint32_t *	phase_acc,
		int32_t	phase_rate,
		int	scale,
		int32_t	phase
	)

Generate an integer tone sample, with modulation.

Parameters:

	phase_acc	A pointer to a phase accumulator value.
	phase_rate	The phase increment to be applied.
	scale	The scaling factor.
	phase	The phase offset.

Returns:

The signal amplitude.

int16_t dds_offset	(	uint32_t	phase_acc,
		int32_t	phase_offset
	)

Find the amplitude for a particular phase offset from an accumulated phase.

Parameters:

	phase_acc	The accumulated phase.
	phase_offset	The phase offset.

Returns:

The signal amplitude.

int32_t dds_phase_step

(

float

frequency

)

Find the phase step value to achieve a particular frequency.

Parameters:

frequency

The desired frequency, in Hertz.

Returns:

The phase rate which while achieve the desired frequency.

int dds_scaling_dbm0

(

float

level

)

Find the scaling factor needed to achieve a specified level in dBm0.

Parameters:

level

The desired signal level, in dBm0.

Returns:

The scaling factor.

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