Overview

Numerically-controlled oscillator

Discussion

Implements a discrete-time oscillator by using the input signal to adjust the nominal frequency driving a sinusoid generator. The output is $y[n] = \sin (omega_o nT + \sum_{k=0}^n x[k] + \phi)$ where $\omega_o$ is the nominal frequency in radians/s, T is the sample period and $\phi$ is the starting phase in radians (default is 0).

The internal variable freq caches the nominal frequency in units of radians/second. phase maintains the current phase in radians between blocks

Type Definition

typedef struct _ModuleOscillator
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    FLOAT32 freqhz;                               // Nominal oscillator frequency in Hz
    FLOAT32 startPhase;                           // Starting phase oscillator in multiples of pi radians
    FLOAT32 freq;                                 // Current oscillator frequency
    FLOAT32* phase;                               // Current oscillator phase
} ModuleOscillatorClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
freqhz	float	parameter	0	0	0:5000	Hz
startPhase	float	parameter	0	0	-1:1	x pi radians
freq	float	state	1	0	Unrestricted	radians/s
phase	float*	state	1	[1 x 1]	Unrestricted	radians

Pins

Input Pins

Name: control

Description: Frequency control input

Data type: float

Channel range: 1

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: Oscillator output

Data type: float

MATLAB Usage

File Name: oscillator_module.m

 This module implements a sinusiodal oscillator whose output frequency is
 determined by the input signal. It is derived from the sine generator.
 Arguments:
   NAME - name of the module.
   QUAD - true means the output is 2 channels in quadrature