Overview

Converts sample rate of input wire and outputs data at new sample rate.

Discussion

Sample rate converter.\n The output sample rate is computed by L/D*SampleRateIn = SampleRateOut. If the ratio of the input sample rate to the desired output sample rate is irrational, the desired output sample rate will not equal the actual output sample rate. The input block size must be an interger multiple of D. The length of the filter must be > than L. L, D, and the optimal value for N can be calculated using the inspector.

Type Definition

typedef struct _ModuleUpFIRDnConverter
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    FLOAT32 gd;                                   // Group Delay or latency, calculated result
    INT32 KAISER;                                 // Filter type constant
    INT32 PARKS_MCCLELLAN;                        // Filter type constant
    INT32 CUSTOM;                                 // Filter type constant
    FLOAT32 fin;                                  // Input Sample Rate
    INT32 L;                                      // Interpolation factor
    INT32 D;                                      // Decimation factor
    INT32 filterType;                             // filter type of FIR
    INT32 ND;                                     // Integer multiplication factor
    INT32 N;                                      // length of FIR filter
    INT32 NQ;                                     // Size of QBUF, >= 2*Q, where Q = N/L (integer divide)
    INT32 IQ;                                     // QBUF index
    INT32 JQ;                                     // QBUF index, moving address index.
    INT32 NC;                                     // Size of array COFS
    INT32 NCOEF;                                  // Size of COEF array
    FLOAT32* QBUF;                                // Internal buffer for storage of state variables of FIR filter
    INT32* ICTR;                                  // Buffer for storing control data
    FLOAT32* COEF;                                // FIR symmetric filter coeffs
    FLOAT32* COFS;                                // scrambled coeffs for FIR filter
} ModuleUpFIRDnConverterClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
gd	float	const	0	0.1319	Unrestricted	msec
KAISER	int	const	1	1	Unrestricted
PARKS_MCCLELLAN	int	const	1	2	Unrestricted
CUSTOM	int	const	1	3	Unrestricted
fin	float	parameter	1	48000	Unrestricted
L	int	const	1	3	Unrestricted
D	int	const	1	4	Unrestricted
filterType	int	const	1	1	Unrestricted
ND	int	derived	1	8	Unrestricted
N	int	const	1	39	Unrestricted
NQ	int	const	1	26	Unrestricted
IQ	int	const	1	13	Unrestricted
JQ	int	derived	1	13	Unrestricted
NC	int	const	1	39	Unrestricted
NCOEF	int	const	1	20	Unrestricted
QBUF	float*	derived	1	[1 x 26]	Unrestricted
ICTR	int*	derived	1	[6 x 1]	Unrestricted
COEF	float*	derived	0	[20 x 1]	Unrestricted
COFS	float*	derived	1	[39 x 1]	Unrestricted

Pins

Input Pins

Name: in

Description: Input signal

Data type: float

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: Output signal

Data type: float

MATLAB Usage

File Name: up_fir_dn_converter_module.m

 M=up_fir_dn_converter_module(NAME, L, D, N, filterType)
 Performs rational sample rate conversion
 Arguments:
     NAME - Name of the module
     L - Interpolation factor
     D - Decimation factor
     N - length of FIR filter used in the conversion process
     filterType - Type of filter
 Author: Darrel Judd