393 lines
12 KiB
C++
393 lines
12 KiB
C++
/*
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* Copyright 2008 Free Software Foundation, Inc.
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*
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* This software is distributed under the terms of the GNU Affero Public License.
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* See the COPYING file in the main directory for details.
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*
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* This use of this software may be subject to additional restrictions.
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* See the LEGAL file in the main directory for details.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "Vector.h"
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#include "Complex.h"
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#include "GSMTransfer.h"
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using namespace GSM;
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/** Indicated signalVector symmetry */
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enum Symmetry {
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NONE = 0,
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ABSSYM = 1
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};
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/** Convolution type indicator */
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enum ConvType {
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FULL_SPAN = 0,
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OVERLAP_ONLY = 1,
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START_ONLY = 2,
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WITH_TAIL = 3,
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NO_DELAY = 4,
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CUSTOM = 5,
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UNDEFINED = 255
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};
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/** the core data structure of the Transceiver */
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class signalVector: public Vector<complex>
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{
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private:
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Symmetry symmetry; ///< the symmetry of the vector
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bool realOnly; ///< true if vector is real-valued, not complex-valued
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public:
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/** Constructors */
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signalVector(int dSize=0, Symmetry wSymmetry = NONE):
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Vector<complex>(dSize),
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realOnly(false)
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{
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symmetry = wSymmetry;
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};
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signalVector(complex* wData, size_t start,
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size_t span, Symmetry wSymmetry = NONE):
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Vector<complex>(NULL,wData+start,wData+start+span),
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realOnly(false)
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{
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symmetry = wSymmetry;
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};
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signalVector(const signalVector &vec1, const signalVector &vec2):
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Vector<complex>(vec1,vec2),
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realOnly(false)
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{
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symmetry = vec1.symmetry;
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};
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signalVector(const signalVector &wVector):
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Vector<complex>(wVector.size()),
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realOnly(false)
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{
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wVector.copyTo(*this);
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symmetry = wVector.getSymmetry();
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};
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/** symmetry operators */
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Symmetry getSymmetry() const { return symmetry;};
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void setSymmetry(Symmetry wSymmetry) { symmetry = wSymmetry;};
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/** real-valued operators */
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bool isRealOnly() const { return realOnly;};
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void isRealOnly(bool wOnly) { realOnly = wOnly;};
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};
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/** Convert a linear number to a dB value */
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float dB(float x);
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/** Convert a dB value into a linear value */
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float dBinv(float x);
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/** Compute the energy of a vector */
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float vectorNorm2(const signalVector &x);
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/** Compute the average power of a vector */
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float vectorPower(const signalVector &x);
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/** Setup the signal processing library */
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void sigProcLibSetup(int samplesPerSymbol);
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/** Destroy the signal processing library */
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void sigProcLibDestroy(void);
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/**
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Convolve two vectors.
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@param a,b The vectors to be convolved.
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@param c, A preallocated vector to hold the convolution result.
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@param spanType The type/span of the convolution.
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@return The convolution result.
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*/
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signalVector* convolve(const signalVector *a,
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const signalVector *b,
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signalVector *c,
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ConvType spanType,
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unsigned startIx = 0,
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unsigned len = 0);
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/**
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Generate the GSM pulse.
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@param samplesPerSymbol The number of samples per GSM symbol.
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@param symbolLength The size of the pulse.
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@return The GSM pulse.
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*/
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signalVector* generateGSMPulse(int samplesPerSymbol,
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int symbolLength);
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/**
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Frequency shift a vector.
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@param y The frequency shifted vector.
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@param x The vector to-be-shifted.
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@param freq The digital frequency shift
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@param startPhase The starting phase of the oscillator
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@param finalPhase The final phase of the oscillator
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@return The frequency shifted vector.
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*/
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signalVector* frequencyShift(signalVector *y,
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signalVector *x,
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float freq = 0.0,
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float startPhase = 0.0,
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float *finalPhase=NULL);
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/**
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Correlate two vectors.
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@param a,b The vectors to be correlated.
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@param c, A preallocated vector to hold the correlation result.
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@param spanType The type/span of the correlation.
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@return The correlation result.
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*/
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signalVector* correlate(signalVector *a,
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signalVector *b,
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signalVector *c,
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ConvType spanType,
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bool bReversedConjugated = false,
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unsigned startIx = 0,
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unsigned len = 0);
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/** Operate soft slicer on real-valued portion of vector */
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bool vectorSlicer(signalVector *x);
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/** GMSK modulate a GSM burst of bits */
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signalVector *modulateBurst(const BitVector &wBurst,
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const signalVector &gsmPulse,
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int guardPeriodLength,
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int samplesPerSymbol);
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/** Sinc function */
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float sinc(float x);
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/** Delay a vector */
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void delayVector(signalVector &wBurst,
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float delay);
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/** Add two vectors in-place */
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bool addVector(signalVector &x,
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signalVector &y);
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/** Generate a vector of gaussian noise */
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signalVector *gaussianNoise(int length,
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float variance = 1.0,
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complex mean = complex(0.0));
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/**
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Given a non-integer index, interpolate a sample.
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@param inSig The signal from which to interpolate.
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@param ix The index.
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@return The interpolated signal value.
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*/
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complex interpolatePoint(const signalVector &inSig,
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float ix);
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/**
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Given a correlator output, locate the correlation peak.
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@param rxBurst The correlator result.
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@param peakIndex Pointer to value to receive interpolated peak index.
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@param avgPower Power to value to receive mean power.
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@return Peak value.
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*/
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complex peakDetect(const signalVector &rxBurst,
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float *peakIndex,
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float *avgPwr);
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/**
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Apply a scalar to a vector.
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@param x The vector of interest.
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@param scale The scalar.
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*/
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void scaleVector(signalVector &x,
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complex scale);
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/**
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Add a constant offset to a vecotr.
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@param x The vector of interest.
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@param offset The offset.
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*/
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void offsetVector(signalVector &x,
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complex offset);
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/**
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Generate a modulated GSM midamble, stored within the library.
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@param gsmPulse The GSM pulse used for modulation.
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@param samplesPerSymbol The number of samples per GSM symbol.
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@param TSC The training sequence [0..7]
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@return Success.
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*/
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bool generateMidamble(signalVector &gsmPulse,
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int samplesPerSymbol,
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int TSC);
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/**
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Generate a modulated RACH sequence, stored within the library.
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@param gsmPulse The GSM pulse used for modulation.
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@param samplesPerSymbol The number of samples per GSM symbol.
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@return Success.
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*/
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bool generateRACHSequence(signalVector &gsmPulse,
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int samplesPerSymbol);
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/**
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Energy detector, checks to see if received burst energy is above a threshold.
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@param rxBurst The received GSM burst of interest.
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@param windowLength The number of burst samples used to compute burst energy
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@param detectThreshold The detection threshold, a linear value.
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@param avgPwr The average power of the received burst.
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@return True if burst energy is above threshold.
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*/
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bool energyDetect(signalVector &rxBurst,
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unsigned windowLength,
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float detectThreshold,
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float *avgPwr = NULL);
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/**
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RACH correlator/detector.
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@param rxBurst The received GSM burst of interest.
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@param detectThreshold The threshold that the received burst's post-correlator SNR is compared against to determine validity.
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@param samplesPerSymbol The number of samples per GSM symbol.
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@param amplitude The estimated amplitude of received RACH burst.
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@param TOA The estimate time-of-arrival of received RACH burst.
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@return True if burst SNR is larger that the detectThreshold value.
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*/
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bool detectRACHBurst(signalVector &rxBurst,
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float detectThreshold,
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int samplesPerSymbol,
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complex *amplitude,
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float* TOA);
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/**
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Normal burst correlator, detector, channel estimator.
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@param rxBurst The received GSM burst of interest.
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@param detectThreshold The threshold that the received burst's post-correlator SNR is compared against to determine validity.
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@param samplesPerSymbol The number of samples per GSM symbol.
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@param amplitude The estimated amplitude of received TSC burst.
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@param TOA The estimate time-of-arrival of received TSC burst.
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@param maxTOA The maximum expected time-of-arrival
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@param requestChannel Set to true if channel estimation is desired.
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@param channelResponse The estimated channel.
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@param channelResponseOffset The time offset b/w the first sample of the channel response and the reported TOA.
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@return True if burst SNR is larger that the detectThreshold value.
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*/
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bool analyzeTrafficBurst(signalVector &rxBurst,
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unsigned TSC,
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float detectThreshold,
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int samplesPerSymbol,
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complex *amplitude,
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float *TOA,
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unsigned maxTOA,
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bool requestChannel = false,
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signalVector** channelResponse = NULL,
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float *channelResponseOffset = NULL);
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/**
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Decimate a vector.
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@param wVector The vector of interest.
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@param decimationFactor The amount of decimation, i.e. the decimation factor.
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@return The decimated signal vector.
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*/
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signalVector *decimateVector(signalVector &wVector,
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int decimationFactor);
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/**
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Demodulates a received burst using a soft-slicer.
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@param rxBurst The burst to be demodulated.
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@param gsmPulse The GSM pulse.
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@param samplesPerSymbol The number of samples per GSM symbol.
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@param channel The amplitude estimate of the received burst.
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@param TOA The time-of-arrival of the received burst.
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@return The demodulated bit sequence.
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*/
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SoftVector *demodulateBurst(signalVector &rxBurst,
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const signalVector &gsmPulse,
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int samplesPerSymbol,
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complex channel,
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float TOA);
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/**
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Creates a simple Kaiser-windowed low-pass FIR filter.
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@param cutoffFreq The digital 3dB bandwidth of the filter.
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@param filterLen The number of taps in the filter.
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@param gainDC The DC gain of the filter.
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@return The desired LPF
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*/
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signalVector *createLPF(float cutoffFreq,
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int filterLen,
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float gainDC = 1.0);
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/**
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Change sampling rate of a vector via polyphase resampling.
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@param wVector The vector to be resampled.
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@param P The numerator, i.e. the amount of upsampling.
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@param Q The denominator, i.e. the amount of downsampling.
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@param LPF An optional low-pass filter used in the resampling process.
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@return A vector resampled at P/Q of the original sampling rate.
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*/
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signalVector *polyphaseResampleVector(signalVector &wVector,
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int P, int Q,
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signalVector *LPF);
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/**
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Change the sampling rate of a vector via linear interpolation.
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@param wVector The vector to be resampled.
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@param expFactor Ratio of new sampling rate/original sampling rate.
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@param endPoint ???
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@return A vector resampled a expFactor*original sampling rate.
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*/
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signalVector *resampleVector(signalVector &wVector,
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float expFactor,
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complex endPoint);
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/**
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Design the necessary filters for a decision-feedback equalizer.
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@param channelResponse The multipath channel that we're mitigating.
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@param SNRestimate The signal-to-noise estimate of the channel, a linear value
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@param Nf The number of taps in the feedforward filter.
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@param feedForwardFilter The designed feed forward filter.
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@param feedbackFilter The designed feedback filter.
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@return True if DFE can be designed.
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*/
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bool designDFE(signalVector &channelResponse,
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float SNRestimate,
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int Nf,
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signalVector **feedForwardFilter,
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signalVector **feedbackFilter);
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/**
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Equalize/demodulate a received burst via a decision-feedback equalizer.
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@param rxBurst The received burst to be demodulated.
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@param TOA The time-of-arrival of the received burst.
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@param samplesPerSymbol The number of samples per GSM symbol.
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@param w The feed forward filter of the DFE.
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@param b The feedback filter of the DFE.
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@return The demodulated bit sequence.
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*/
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SoftVector *equalizeBurst(signalVector &rxBurst,
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float TOA,
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int samplesPerSymbol,
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signalVector &w,
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signalVector &b);
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