LiquidDSP

This Julia package is a wrapper for Joseph Gaeddert's excellent digital communications library, liquid-dsp.

Usage

This package follows liquid-dsp's calling conventions fairly closely, with a few exceptions. The biggest difference is the use of CamelCase for object names, and the lack of type signatures in function names.

liquid-dsp c code

// Create firdecim object with:
//      a decimation factor of 2
//      an already defined vector of taps named h
//      of length h_len

firdecim_rrrf myfilt = firdecim_rrrf_create(2, h, h_len);

// Execute filter on an array of float samples
//      myfilt is the firdecim object created above
//      x is holds the output samples
//      n_out is the number of output samples
//      y is the buffer to write the output samples to

firdecim_rrrf_execute_block(myfilt, x, n_out, y);

LiquidDSP.jl Equivalent Julia code

# Create firdecim object with:
#      a decimation factor of 2
#      an already defined vector of taps named h
#      an input type of Float32

myfilt = LiquidDSP.FIRDecim(Float32, 2, h)

# Execute myfilt on a vector of input samples named x

y = execute(myfilt, x)

Objects and methods implemented

Filter object constructors

Constructor	Description
obj = FIRFilt([eltype(x),] h)	Creates a FIRFilt
obj = FIRDecim([eltype(x),], M, h)	Create a FIRDecim object with integer decimation factor M
obj = FIRInterp([eltype(x),], L, h)	Create a FIRInterp object with integer interpolation factor L

Filter object methods

Constructor	Description	Valid obj types
y = execute(obj, x)	Filter vector x	FIRFilt, FIRDecim, FIRInterp
reset!(obj)	Reset obj to its initial state	FIRFilt, FIRDecim, FIRInterp
h = gettaps(obj)	Returns obj's internal coefficients	FIRFilt, FIRDecim
r = freqresponse(obj, ƒ)	Get the frequency response of obj where 0≤ƒ≤0.5	FIRFilt
d = groupdelay(obj, ƒ)	Get the group delay of obj where 0≤ƒ≤0.5	FIRFilt