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/*
* Copyright 2008 Free Software Foundation, Inc.
*
* This software is distributed under multiple licenses; see the COPYING file in the main directory for licensing information for this specific distribuion.
*
* This use of this software may be subject to additional restrictions.
* See the LEGAL file in the main directory for details.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef SIGPROCLIB_H
#define SIGPROCLIB_H
#include "Vector.h"
#include "Complex.h"
#include "BitVector.h"
#include "signalVector.h"
/* Burst lengths */
#define NORMAL_BURST_NBITS 148
#define EDGE_BURST_NBITS 444
#define EDGE_BURST_NSYMS (EDGE_BURST_NBITS / 3)
/** Codes for burst types of received bursts*/
enum CorrType{
OFF, ///< timeslot is off
TSC, ///< timeslot should contain a normal burst
RACH, ///< timeslot should contain an access burst
EDGE, ///< timeslot should contain an EDGE burst
IDLE ///< timeslot is an idle (or dummy) burst
};
enum SignalError {
SIGERR_NONE,
SIGERR_BOUNDS,
SIGERR_CLIP,
SIGERR_UNSUPPORTED,
SIGERR_INTERNAL,
};
/*
* Burst detection threshold
*
* Decision threshold value for burst gating on peak-to-average value of
* correlated synchronization sequences. Lower values pass more bursts up
* to upper layers but will increase the false detection rate.
*/
#define BURST_THRESH 4.0
/** Setup the signal processing library */
bool sigProcLibSetup();
/** Destroy the signal processing library */
void sigProcLibDestroy(void);
/** Operate soft slicer on a soft-bit vector */
bool vectorSlicer(SoftVector *x);
/** GMSK modulate a GSM burst of bits */
signalVector *modulateBurst(const BitVector &wBurst,
int guardPeriodLength,
int sps, bool emptyPulse = false);
/** 8-PSK modulate a burst of bits */
signalVector *modulateEdgeBurst(const BitVector &bits,
int sps, bool emptyPulse = false);
/** Generate a EDGE burst with random payload - 4 SPS (625 samples) only */
signalVector *generateEdgeBurst(int tsc);
/** Generate an empty burst - 4 or 1 SPS */
signalVector *generateEmptyBurst(int sps, int tn);
/** Generate a normal GSM burst with random payload - 4 or 1 SPS */
signalVector *genRandNormalBurst(int tsc, int sps, int tn);
/** Generate an access GSM burst with random payload - 4 or 1 SPS */
signalVector *genRandAccessBurst(int delay, int sps, int tn);
/** Generate a dummy GSM burst - 4 or 1 SPS */
signalVector *generateDummyBurst(int sps, int tn);
/**
Apply a scalar to a vector.
@param x The vector of interest.
@param scale The scalar.
*/
void scaleVector(signalVector &x,
complex scale);
/**
Rough energy estimator.
@param rxBurst A GSM burst.
@param windowLength The number of burst samples used to compute burst energy
@return The average power of the received burst.
*/
float energyDetect(const signalVector &rxBurst,
unsigned windowLength);
/**
8-PSK/GMSK/RACH burst detector
@param burst The received GSM burst of interest
@param tsc Midamble type (0..7) also known as TSC
@param threshold The threshold that the received burst's post-correlator SNR is compared against to determine validity.
@param sps The number of samples per GSM symbol.
@param amplitude The estimated amplitude of received TSC burst.
@param toa The estimate time-of-arrival of received TSC burst (in symbols).
@param max_toa The maximum expected time-of-arrival (in symbols).
@return positive value (CorrType) if threshold value is reached,
negative value (-SignalError) on error,
zero (SIGERR_NONE) if no burst is detected
*/
int detectAnyBurst(const signalVector &burst,
unsigned tsc,
float threshold,
int sps,
CorrType type,
complex &,
float &toa,
unsigned max_toa);
/** Demodulate burst basde on type and output soft bits */
SoftVector *demodAnyBurst(const signalVector &burst, int sps,
complex amp, float toa, CorrType type);
#endif /* SIGPROCLIB_H */
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