AIRSAR Synoptic Data Description

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AIRSAR Data Compression Formats


	For AIRSAR data, there are four possible formats :  

		1) compressed stokes matrix data 
			(multilook,quad-pol, low-res, 10 bytes/pixel)
		2) compressed scattering matrix (730 processor) data 
			(single look,quad-pol,10 bytes/pixel)
		3) compressed scattering matrix (3.5 processor) data 
			(single look,quad-pol, low-res, 10 bytes/pixel)
		4) uncompressed synoptic amplitude data 
			(vax real*4, single pol, low-res, 4 bytes/pixel)
	In the following descriptions:
	
		sign( ) will return the sign of the argument ( ± 1) 

		nint( ) will indicate that the nearest integer value is calculated of its 
argument.  

		int( ) will indicate that the truncation of the floating point value to integer 
is calculated of its argument, and that, if the floating point value is less than zero, 
subtraction by 1.0 is additionally required.  Note that this is not the same as FORTRAN 
int( ).

		gen_fac is the AIRSAR general scale factor whose value is recorded in the 
header of the oldheader, field 133.


Detected data products

	AIRSAR synoptic amplitude data - 4 bytes per pixel.  This data is not 
compressed.  Consists of one file for each scene, per channel processed (usually three).  
Each line of the file consists of 1279 range samples, in which range increases with sample 
number.  There are 5090 lines per file, in which each line corresponds to different 
azimuth or along track locations.  The azimuth pixel spacing is 12.1 meters for the pre-
1993 prf, and 8 meters for the 1993 and later prf.  The range pixel spacing is 6.66 meters 
(assumes 20 MHz data).  The first two lines in the file are header lines. The data has been 
multilooked by 16, and the pixels are amplitude rather than power values.  The format is 
that each pixel is a four byte DEC VAX floating point number.  There is no general scale 
factor that is used.