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Path.cpp
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Path.cpp
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#include "Path.h"
#define K_2PI ( 8.0 * atan(1.0) ) // 2 Pi
#define OFFSET_FREQ_CONST (K_2PI/8000.0) //2Pi/8000
#define KGNB 0.62665707 //equivalent Noise BW of Gaussian shaped filter
#define RATE_12_8 0 //Used for 0.1 > Spread >= 0.4
#define RATE_64 1 //Used for 0.4 > Spread >= 2.0
#define RATE_320 2 //Used for 2.0 > Spread >= 10.0
namespace PathSim {
Path::Path()
{
m_Indx = 0;
m_NoiseSampRate = RATE_320;
}
void Path::InitPath( double Spread, double Offset, int blocksize, int numpaths, bool active)
{
m_BlockSize = blocksize;
m_Offset = Offset;
m_Spread = Spread;
m_PathActive = active;
m_FirState0 = INTP_QUE_SIZE-1;
m_FirState1 = INTP_QUE_SIZE-1;
m_FirState2 = INTP_QUE_SIZE-1;
m_FirState3 = INTP_QUE_SIZE-1;
m_Indx = 0;
m_inc = 0;
m_Timeinc = 0.0;
if( (m_Spread > 2.0) && (m_Spread <= 30.0) )
{
m_NoiseSampRate = RATE_320;
m_lpfir.Init( 320.0, m_Spread );
m_LPGain = sqrt(320.0/(4.0*m_Spread*KGNB) );
}
else if( (m_Spread > 0.4) && (m_Spread <= 2.0) )
{
m_NoiseSampRate = RATE_64;
m_lpfir.Init( 64.0, m_Spread );
m_LPGain = sqrt(64.0/(4.0*m_Spread*KGNB) );
}
else if( (m_Spread >= 0.1) && (m_Spread <= 0.4) )
{
m_NoiseSampRate = RATE_12_8;
m_lpfir.Init( 12.8, m_Spread );
m_LPGain = sqrt(12.8/(4.0*m_Spread*KGNB) );
}
else if( (m_Spread >= 0.0) && (m_Spread < 0.1) )
{ //here if spread<.1 so will not use any spread just offset
m_NoiseSampRate = RATE_320;
m_LPGain = 1.0;
}
for(int i=0; i<INTP_QUE_SIZE; i++)
{
m_pQue0[i].x = 0.0; m_pQue0[i].y = 0.0;
m_pQue1[i].x = 0.0; m_pQue1[i].y = 0.0;
m_pQue2[i].x = 0.0; m_pQue2[i].y = 0.0;
m_pQue3[i].x = 0.0; m_pQue3[i].y = 0.0;
}
m_LPGain = m_LPGain/ sqrt((double)numpaths);
for(int i=0; i<250; i++)
MakeGaussianDelaySample(); //pre load filter
}
//////////////////////////////////////////////////////////////////////
// Performs a path calculation on pIn and puts it in pOut
//
// Two Low Pass filtered Gaussian random numbers are created at
// 12.8, 64 Hz, or 320 Hz rate. These form the input to a complex
// interpolation filter that bumps the sample rate up to 8000Hz.
//
// Two, three, or four stages of X5 upsampling/interpolation are used.
// The complex noise is then multiplied by the input I/Q signal
// to produce the spreading/fading simulation.
//
// Finally a complex NCO is multiplied by the signal to produce a
// Frequency offset.
//////////////////////////////////////////////////////////////////////
void Path::CalcPath(cmplx *pIn, cmplx *pOut)
{
int i,j;
cmplx acc;
cmplx tmp;
const double* Kptr;
cmplx* Firptr;
cmplx offset;
if(m_PathActive) // if this path is active
{
for(i=0; i<m_BlockSize; i++)
{
if( m_NoiseSampRate == RATE_12_8)
{
if( m_Indx%(5*5*5*5) == 0 )
{ //generate noise samples at 12.8Hz rate
acc = MakeGaussianDelaySample();
//SweepGenCpx( &acc, 12.8, 0.0, 6.4, 0.016 );
j = m_FirState0/INTP_VALUE;
m_pQue0[j].x = acc.x;
m_pQue0[j].y = acc.y;
}
}
if( m_NoiseSampRate <= RATE_64)
{
if( m_Indx%(5*5*5) == 0 )
{
if( m_NoiseSampRate == RATE_64)
{ //generate noise samples at 64Hz rate
acc = MakeGaussianDelaySample();
}
else
{
acc.x = 0.0; acc.y = 0.0;
Firptr = m_pQue0;
Kptr = X5IntrpFIRCoef+INTP_FIR_SIZE-m_FirState0;
for(j=0; j<INTP_QUE_SIZE; j++)
{
acc.x += ( (Firptr->x)*(*Kptr) );
acc.y += ( (Firptr++->y)*(*Kptr) );
Kptr += INTP_VALUE;
}
if( --m_FirState0 < 0)
m_FirState0 = INTP_FIR_SIZE-1;
}
//SweepGenCpx( &acc, 64, 0.0, 32.0, 0.08 );
j = m_FirState1/INTP_VALUE;
m_pQue1[j].x = acc.x;
m_pQue1[j].y = acc.y;
}
}
if( m_Indx%(5*5) == 0 ) //interpolate/upsample x5
{
if( m_NoiseSampRate == RATE_320)
{
acc = MakeGaussianDelaySample();
}
else
{
acc.x = 0.0; acc.y = 0.0;
Firptr = m_pQue1;
Kptr = X5IntrpFIRCoef+INTP_FIR_SIZE-m_FirState1;
for(j=0; j<INTP_QUE_SIZE; j++)
{
acc.x += ( (Firptr->x)*(*Kptr) );
acc.y += ( (Firptr++->y)*(*Kptr) );
Kptr += INTP_VALUE;
}
if( --m_FirState1 < 0)
m_FirState1 = INTP_FIR_SIZE-1;
}
//SweepGenCpx( &acc, 320, 0.0, 160.0, 0.4 );
j = m_FirState2/INTP_VALUE;
m_pQue2[j].x = acc.x;
m_pQue2[j].y = acc.y;
}
if( m_Indx%(5) == 0 ) //interpolate/upsample x5
{
acc.x = 0.0; acc.y = 0.0;
Firptr = m_pQue2;
Kptr = X5IntrpFIRCoef+INTP_FIR_SIZE-m_FirState2;
for(j=0; j<INTP_QUE_SIZE; j++)
{
acc.x += ( (Firptr->x)*(*Kptr) );
acc.y += ( (Firptr++->y)*(*Kptr) );
Kptr += INTP_VALUE;
}
if( --m_FirState2 < 0)
m_FirState2 = INTP_FIR_SIZE-1;
//SweepGenCpx( &acc, 1600, 0.0, 800.0, 2 );
j = m_FirState3/INTP_VALUE;
m_pQue3[j].x = acc.x;
m_pQue3[j].y = acc.y;
}
acc.x = 0.0; acc.y = 0.0;
Firptr = m_pQue3;
Kptr = X5IntrpFIRCoef+INTP_FIR_SIZE-m_FirState3;
for(j=0; j<INTP_QUE_SIZE; j++)
{
acc.x += ( (Firptr->x)*(*Kptr) );
acc.y += ( (Firptr++->y)*(*Kptr) );
Kptr += INTP_VALUE;
}
if( --m_FirState3 < 0)
m_FirState3 = INTP_FIR_SIZE-1;
//CalcCpxSweepRMS( acc, 8000);
tmp.x = (acc.x*pIn[i].x - acc.y*pIn[i].y);
tmp.y = (acc.x*pIn[i].y + acc.y*pIn[i].x);
offset.x = cos(m_Timeinc); //Cpx multiply by offset frequency
offset.y = sin(m_Timeinc);
pOut[i].x = ((offset.x*tmp.x) - (offset.y*tmp.y));
pOut[i].y = ((offset.x*tmp.y) + (offset.y*tmp.x));
m_Timeinc += (OFFSET_FREQ_CONST*m_Offset);
m_Timeinc = fmod(m_Timeinc,K_2PI); //keep radian counter bounded
if( ++m_Indx > (INTP_VALUE*INTP_VALUE*INTP_VALUE*INTP_VALUE*m_BlockSize) )
m_Indx = 0;
}
}
else // if path is not active just zero the output
{
for(i=0; i<m_BlockSize; i++)
{
pOut[i].x = 0.0;
pOut[i].y = 0.0;
}
}
}
// Create the complex Rayleigh distributed samples by
// creating two Gaussian random distributed numbers for the I and Q
// terms and then passing them through a Gaussian shaped LP IIR.
// The 2 Sigma bandwidth of the LP filter determines the amount of spread.
cmplx Path::MakeGaussianDelaySample()
{
cmplx val;
if (m_Spread >= 0.1) {
// Generate two uniform random numbers between -1 and +1 that are inside the unit circle
double r2;
do {
val.x = 1.0 - 2.0 * (double)rand()/(double)RAND_MAX;
val.y = 1.0 - 2.0 * (double)rand()/(double)RAND_MAX;
r2 = val.x * val.x + val.y * val.y;
} while (r2 >= 1.0 || r2 == 0.0);
double scale = m_LPGain * sqrt(- 2.0 * log(r2) / r2);
val.x *= scale;
val.y *= scale;
//SweepGenCpx( &val, 320, 0.0, 30*5, 30*5/200.0);
// Now LP filter the Gaussian samples
val = m_lpfir.CalcFilter(val);
} else
{
// Not using any spread.
val.x = m_LPGain;
val.y = 0;
}
//gDebug1 = CalcCpxRMS( val, 288000);
//CalcCpxSweepRMS( val, 500);
return val;
}
} // namespace PathSim