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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

Code Block
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

...

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: Oscillator output

Data type: float

MATLAB Usage

File Name: oscillator_module.m

...