sar_range_compress

Capsim Block Documentation

Short Description

Compress SAR image in range

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Input Connections
Port Type Name
0 float x
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Parameters
Num Description Type Name Default Value
0 Carrier Frequency, MHz float fc 1275
1 Pulse Chirp Rate, MHz/microsecond float Kr 0.5621
2 Pulse Duration Microseconds float tau 33.8
3 Pulse Bandwidth, MHz float Br 19.0
4 Center Frequency (IF) MHz float fIF 11.38
5 Pulse Repition Rate, Hz float prf 1645.0
6 Sampling Rate, MHz float fs 45.03
7 Doppler Frequency, Hz float fDc 1150.0
8 Doppler Rate of Change , Hz float Kaz 501.27
9 Platform Velocity, Km/s float v 7.0
10 Integration Time, s float total 2.0
11 Azimuth Sample Time float tazs 0.0
12 tc seconds float tc 1.0
13 Reference Point Range rp, kM float rp 840.0
14 Reference Point Azimuth tp in index units int tpi 1000
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States
Num Type Name Initial Value Description
0 float phase 0.
1 float t 0.
2 float dt
3 float dtaz
4 float tp
5 int done 0
6 int maxRangeIndex
7 int k
8 float lamda
9 float t0
10 int obufs
11 cap_fft_cpx* ref_P
12 cap_fft_cpx* range_P
13 cap_fft_cpx* refFFT_P
14 cap_fft_cpx* rangeFFT_P
15 cap_fft_cfg cfg
16 cap_fft_cfg cfgi
17 int rangeFFTLength
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Declarations


 

	int no_samples;
	int i,j,jj;
	float taz;
	float range;
	float arg;
	float a,b,c;
	float rx;
	image_t		img;
	int order,pts;
	cap_fft_cpx x,y;
	float fmax,fmin;
	float sample;
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Initialization Code



 

	if( (obufs = NO_OUTPUT_BUFFERS()) < 1 ) {
		fprintf(stderr,"sar_range_compress: no output buffers\n");
		CsInfo("sar_range_compress: no output buffers");
		return(2);
	}
    dt=(1.0/fs)*0.000001;
	t0=2.0*rp*1000.0/C;
    maxRangeIndex=(int)tau*0.000001/dt;
	dtaz=(1.0/prf);
    tp=tpi*(1.0/prf);
    done=0;
    t=0;
    k=0;
    lamda=C/(fc*1000000.0);
// 	fprintf(stderr,"sar_range_compress: width=%d height=%d\n",maxRangeIndex,maxAzimuthIndex); 
	/*
	 * round maxRangeIndex to next power of 2
	 */
	order = (int) (log((float)maxRangeIndex)/log(2.0)+0.5);
	pts = 1 << order;
	if (pts < maxRangeIndex ) {
        	pts = pts*2;
        	order += 1;
	}
	rangeFFTLength=pts;
//	fprintf(stderr,"sar_range_compress: width=%d height=%d FFTWidth=%d\n",width,height,rangeFFTLength); 
	ref_P=(cap_fft_cpx *)calloc(rangeFFTLength,sizeof(cap_fft_cpx));
	range_P=(cap_fft_cpx *)calloc(rangeFFTLength,sizeof(cap_fft_cpx));
	refFFT_P=(cap_fft_cpx *)calloc(rangeFFTLength,sizeof(cap_fft_cpx));
	rangeFFT_P=(cap_fft_cpx *)calloc(rangeFFTLength,sizeof(cap_fft_cpx));
	if(ref_P == NULL || range_P== NULL || rangeFFT_P== NULL || refFFT_P== NULL) {
		fprintf(stderr,"sar_range_compress: could not allocate space \n");
		CsInfo("sar_range_compress: could not allocate space");
		return(7);
	}
        cfgi=cap_fft_alloc(rangeFFTLength,1,NULL,NULL);
        cfg=cap_fft_alloc(rangeFFTLength,0,NULL,NULL);
	/*
	 * generate reference
	 */
    for(j=0; j
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Main Code



 


for (no_samples = MIN_AVAIL(); no_samples > 0; --no_samples) {
	IT_IN(0);
	sample=x(0);
	range_P[k].r=sample;
	range_P[k].i=0.0;
	k++;
	if(k==maxRangeIndex) {
	    for(j=maxRangeIndex; j
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Wrapup Code



 

if(range_P) free(range_P);
if(rangeFFT_P) free(rangeFFT_P);
if(refFFT_P) free(refFFT_P);
if(ref_P) free(ref_P);
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License



/*  Capsim (r) Text Mode Kernel (TMK) Star Library (Blocks)
    Copyright (C) 1989-2002  XCAD Corporation 

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    http://capsimtmk.sourceforge.net
    XCAD Corporation
    Raleigh, North Carolina */
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Description



 

/************************************************************************
 *									
 *	
(c) 1989-2002 XCAD Corporation

sar_range_compress


Compress SAR image in range


Sasan Ardalan
								
 ************************************************************************/