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141 lines
4.7 KiB
C
141 lines
4.7 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 multiple licenses; see the COPYING file in the main directory for licensing information for this specific distribution.
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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 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.
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*/
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#ifndef SIGPROCLIB_H
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#define SIGPROCLIB_H
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#include "Vector.h"
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#include "Complex.h"
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#include "BitVector.h"
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#include "signalVector.h"
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/* Burst lengths */
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#define NORMAL_BURST_NBITS 148
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#define EDGE_BURST_NBITS 444
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#define EDGE_BURST_NSYMS (EDGE_BURST_NBITS / 3)
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/** Codes for burst types of received bursts*/
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enum CorrType{
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OFF, ///< timeslot is off
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TSC, ///< timeslot should contain a normal burst
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EXT_RACH, ///< timeslot should contain an extended access burst
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RACH, ///< timeslot should contain an access burst
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EDGE, ///< timeslot should contain an EDGE burst
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IDLE ///< timeslot is an idle (or dummy) burst
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};
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enum SignalError {
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SIGERR_NONE,
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SIGERR_BOUNDS,
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SIGERR_CLIP,
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SIGERR_UNSUPPORTED,
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SIGERR_INTERNAL,
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};
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/*
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* Burst detection threshold
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*
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* Decision threshold value for burst gating on peak-to-average value of
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* correlated synchronization sequences. Lower values pass more bursts up
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* to upper layers but will increase the false detection rate.
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*/
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#define BURST_THRESH 4.0
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/** Setup the signal processing library */
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bool sigProcLibSetup();
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/** Destroy the signal processing library */
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void sigProcLibDestroy(void);
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/** Operate soft slicer on a soft-bit vector */
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void vectorSlicer(float *dest, const float *src, size_t len);
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/** GMSK modulate a GSM burst of bits */
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signalVector *modulateBurst(const BitVector &wBurst,
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int guardPeriodLength,
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int sps, bool emptyPulse = false);
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/** 8-PSK modulate a burst of bits */
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signalVector *modulateEdgeBurst(const BitVector &bits,
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int sps, bool emptyPulse = false);
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/** Generate a EDGE burst with random payload - 4 SPS (625 samples) only */
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signalVector *generateEdgeBurst(int tsc);
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/** Generate an empty burst - 4 or 1 SPS */
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signalVector *generateEmptyBurst(int sps, int tn);
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/** Generate a normal GSM burst with random payload - 4 or 1 SPS */
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signalVector *genRandNormalBurst(int tsc, int sps, int tn);
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/** Generate an access GSM burst with random payload - 4 or 1 SPS */
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signalVector *genRandAccessBurst(int delay, int sps, int tn);
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/** Generate a dummy GSM burst - 4 or 1 SPS */
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signalVector *generateDummyBurst(int sps, int tn);
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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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Rough energy estimator.
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@param rxBurst A GSM burst.
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@param windowLength The number of burst samples used to compute burst energy
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@return The average power of the received burst.
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*/
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float energyDetect(const signalVector &rxBurst,
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unsigned windowLength);
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/** Struct used to fill out parameters in detectAnyBurst(): estimated burst parameters
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@param amplitude The estimated amplitude of received TSC burst.
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@param toa The estimated time-of-arrival of received TSC burst (in symbols).
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@param tsc The TSC used to detect the burst.
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*/
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struct estim_burst_params {
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complex amp;
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float toa;
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uint8_t tsc;
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float ci;
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};
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/**
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8-PSK/GMSK/RACH burst detector
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@param burst The received GSM burst of interest
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@param tsc Midamble type (0..7) also known as TSC
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@param threshold The threshold that the received burst's post-correlator SNR is compared against to determine validity.
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@param sps The number of samples per GSM symbol.
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@param max_toa The maximum expected time-of-arrival (in symbols).
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@param ebp The estimated parameters of the detected burst.
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@return positive value (CorrType) if threshold value is reached,
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negative value (-SignalError) on error,
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zero (SIGERR_NONE) if no burst is detected
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*/
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int detectAnyBurst(const signalVector &burst,
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unsigned tsc,
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float threshold,
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int sps,
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CorrType type,
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unsigned max_toa,
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struct estim_burst_params *ebp);
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/** Demodulate burst basde on type and output soft bits */
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SoftVector *demodAnyBurst(const signalVector &burst, int sps,
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complex amp, float toa, CorrType type);
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#endif /* SIGPROCLIB_H */
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