Data Set Overview
    =================
      The Arecibo 12.6 cm radar data set for Venus consists of scaled
      radar backscatter cross section images generated from data
      obtained in 1983 and 1988.  The images are in raster format
      (one image per record, with no embedded labels).  The original
      images are in 16-bit, unsigned integer,
      most-significant-byte-first format.  Since the volume of the
      entire set of 16-bit images would have exceeded the capacity of
      the CD-ROM, some of the images have been scaled to 8-bit
      versions.  Specifically, the entire set of 1988 images are in
      the scaled 8-bit format, while all the 1983 images are in the
      original 16-bit format.  Both the 16-bit and the 8-bit images
      were provided by Don Campbell, Cornell University.
 
      The 1983 data (acquired in August) cover parts of the northern
      hemisphere of Venus and consist of 4 files.  The first is a
      mosaic in a Mercator projection with a pixel spacing of 0.12
      degrees in longitude.  A grid spaced at 10 degrees in both
      latitude and longitude is embedded in the data.  The remaining
      three files are sections of the mosaic.  The mosaic covers 18
      to 80 degrees north latitude and 250 (leftmost) to 40
      (rightmost) degrees east longitude.  The three sections of the
      1983 mosaic cover the following areas: (a) 18 to 70 north
      latitude, 320 to 40 east longitude; 0.02 degrees long pixel
      spacing; (b) 69 to 80 north latitude, 267 to 21 east longitude,
      0.04 degrees long pixel spacing; (c) 18 to 70 north latitude,
      250 to 331 east longitude, 0.02 degrees longitude pixel
      spacing.  The data correspond to incidence angle ranges of 44
      to 70 degrees, relative to the sub-Earth point.  Polarization
      is circular, with opposite sense receive, so the data consist
      of polarized returns.  For the mosaic, a theoretical antenna
      beam pattern has been removed and the echoes have been
      corrected for a diffuse scattering law by multiplying by the
      cosine of the incidence angle.  Data have been scaled to fit
      within a 16 bit interval.
 
      The 1988 data consist of two groups of images that cover the
      northern and southern hemispheres.  Twenty-five individual
      'looks' were averaged to make each northern hemisphere image,
      whereas 26 looks were averaged for the southern hemisphere
      images.  Incidence angles for most of the coverage are between
      20 and 60 degrees; the extreme range is from 8 to 67 degrees.
      Ground resolution is between 1.5 and 2 km.  The range
      resolution varies from 1.7 km at 20 degrees incidence to 0.8 km
      at 50 degrees; the Doppler resolution (approximately east-west)
      is about 1.3 km.
 
 
      Processing Level Id            : 4
      Software Flag                  : N
      Processing Start Time          : 1983
      Processing Stop Time           : 1990
 
 
    Parameters
    ==========
 
      Data Set Parameter 'RADAR SCALED BACKSCATTER CROSS SECTION'
      -----------------------------------------------------------
        Cross section values that are scaled by some procedure, such
        as dividing by theoretical or empirical scattering laws.
 
        Data Set Parameter Name        : RADAR SCALED BACKSCATTER
                                           CROSS SECTION
        Data Set Parameter Unit        : DIMENSIONLESS
        Sampling Parameter Name        : PIXEL
        Sampling Parameter Unit        : N/A
        Minimum Sampling Parameter     : N/A
        Maximum Sampling Parameter     : N/A
        Sampling Parameter Resolution  : N/A
        Sampling Parameter Interval    : N/A
        Minimum Available Sampling Int : N/A
        Noise Level                    : UNK
 
 
    Source Instrument Parameters
    ============================
      Instrument Host ID              : ARCB
      Data Set Parameter Name         : RADAR SCALED BACKSCATTER
                                          CROSS SECTION
      Instrument Parameter Name       : RADAR ECHO POWER
      Important Instrument Parameters : 1
 
 
    Measurement Information
    =======================
 
      Atmospheric Conditions
      ----------------------
        NOT APPLICABLE
 
 
      Source
      ------
        The observations used the 300 meter reflector at Arecibo for
        transmission.
 
 
      Calibration Standard
      --------------------
        NOT APPLICABLE
 
 
      Wavelength Calibration
      ----------------------
        Transmitter frequency calibrated with a hydrogen maser.
 
 
    Processing
    ==========
      N/A

Overview
    ========
      1988 data have several areas where the image is degraded due to
      cross coupling of power from high backscatter cross section
      features at the ambiguity location in the opposite hemisphere.