sar_chirp

Capsim Block Documentation

Short Description

Generate chirp for SAR

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Output Connections
Port Type Name
0 float outSample
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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 MHz
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 Point Range rp, kM float rp 840.0
14 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 tp
4 int done 0
5 int maxIndex
6 int k
7 float lamda
8 float t0
9 int maxRangeIndex
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Declarations


 

	int no_samples;
	int i,j;
	float taz;
	float range;
	float arg;
	float a,b,c;
	float rx;
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Initialization Code



 

dt=(1.0/fs)*.000001;
maxRangeIndex=(int)tau*0.000001/dt;
tp=tpi*(1.0/prf);
done=0;
maxIndex=(int)total*prf;
t=0;
k=0;
lamda=C/(fc*1000000.0);
t0=2.0*840.0*1000.0/C;
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Main Code



 


if(done)return(0);

for(i=0; i< maxRangeIndex; i++) {

        t=dt*i+t0;
//          t=dt*i;
;
        
 //       taz=(1.0/prf)*i;
        taz=tazs;
        range=rp+(v*v*0.5/rp)*(tc+tp-taz)*(tc+tp-taz);
		a=t-2.0*range*1000.0/C;
		b=a*a;
		b=PI*Kr*b*1e12;
		c=fIF*t*1000000.0-(2.0*range*1000.0/lamda);
		rx=cos(c+b);


//		fprintf(stderr,"%d %f\n",k,range); 

		if(IT_OUT(0) ) {
			KrnOverflow("sar_chirp",0);
			return(99);
		}
		outSample(0)=rx;
}
done=1;

return(0);
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Wrapup Code
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License



/*  Capsim (r) Text Mode Kernel (TMK) Star Library (Blocks)
    Copyright (C) 1989-2017  Silicon DSP 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://www.silicondsp.com
    Silicon DSP  Corporation
    Las Vegas, Nevada
*/
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Description



 

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


Generate chirp for SAR


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