sfft Class Reference

#include <fftfilt.h>

Collaboration diagram for sfft:

Classes
struct	vrot_bins_pair

Public Types
typedef std::complex< float >	cmplx

Public Member Functions
	sfft (int len)
	~sfft ()
void	run (const cmplx &input)
void	fetch (float *result)

Private Attributes
int	fftlen
int	first
int	last
int	ptr
vrot_bins_pair *	vrot_bins
cmplx *	delay
float	k2

Detailed Description

Definition at line 96 of file fftfilt.h.

Member Typedef Documentation

cmplx

typedef std::complex<float> sfft::cmplx

Definition at line 99 of file fftfilt.h.

Constructor & Destructor Documentation

sfft()

sfft::sfft

(

int

len

)

Definition at line 410 of file fftfilt.cpp.

References cos(), i, K1, M_PI, and sin().

{
    vrot_bins = new vrot_bins_pair[len];
    delay  = new cmplx[len];
    fftlen = len;
    first = 0;
    last = len - 1;
    ptr = 0;
    double phi = 0.0, tau = 2.0 * M_PI/ len;
    k2 = 1.0;
    for (int i = 0; i < len; i++) {
        vrot_bins[i].vrot = cmplx( K1 * cos (phi), K1 * sin (phi) );
        phi += tau;
        delay[i] = vrot_bins[i].bins = 0.0;
        k2 *= K1;
    }
}

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~sfft()

sfft::~sfft

(

)

Definition at line 428 of file fftfilt.cpp.

{
    delete [] vrot_bins;
    delete [] delay;
}

Member Function Documentation

fetch()

void sfft::fetch

(

float *

result

)

Definition at line 451 of file fftfilt.cpp.

Referenced by LoRaDemod::detect().

{
    for (vrot_bins_pair *itr = vrot_bins, *end = vrot_bins + last;  itr != end; ++itr, ++result)
        *result = itr->bins.real() * itr->bins.real()
                        + itr->bins.imag() * itr->bins.imag();
}

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run()

void sfft::run

(

const cmplx &

input

)

Definition at line 437 of file fftfilt.cpp.

Referenced by LoRaDemod::detect().

{
    cmplx & de = delay[ptr];
    const cmplx z( input.real() - k2 * de.real(), input.imag() - k2 * de.imag());
    de = input;

    if (++ptr >= fftlen)
        ptr = 0;

    for (vrot_bins_pair *itr = vrot_bins + first, *end = vrot_bins + last; itr != end ; ++itr)
        itr->bins = (itr->bins + z) * itr->vrot;
}

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Member Data Documentation

delay

cmplx* sfft::delay

private

Definition at line 111 of file fftfilt.h.

fftlen

int sfft::fftlen

private

Definition at line 105 of file fftfilt.h.

first

int sfft::first

private

Definition at line 106 of file fftfilt.h.

k2

float sfft::k2

private

Definition at line 112 of file fftfilt.h.

last

int sfft::last

private

Definition at line 107 of file fftfilt.h.

ptr

int sfft::ptr

private

Definition at line 108 of file fftfilt.h.

vrot_bins

vrot_bins_pair* sfft::vrot_bins

private

Definition at line 109 of file fftfilt.h.

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The documentation for this class was generated from the following files:

• sdrbase/dsp/fftfilt.h
• sdrbase/dsp/fftfilt.cpp