Non-statistical method for compressing and decompressing complex SAR data

A non-statistical system for compressing and decompressing complex SAR data derived from a reflected energy, comprising:

• receiving means for receiving complex SAR data collected through an oversampling process;
• selecting means for selecting a first FFT to provide a target ration of pixel spacing to resolution and a second FFT smaller the size of the first FFT;
• first transforming means for zero-padding the data to fill the second FFT and transform the zero-padded data with the second FFT to provide at least one transfer frequency;
• transfer means for transferring the at least one transfer frequency to a remote location;
• inverting means for inverting the second FFT transformation at the remote location to restore the data from the transferred at least one transfer frequency as restored data;
• and
• second transforming means for zero-padding the restored data to fill the first FFT and transforming the zero-padded restored data to provide a data set of points with the target ratio of pixel spacing to resolution.

A non-statistical method for compressing and decompressing complex SAR data derived from a reflected energy, comprising:

• receiving SAR data in complex floating point form at sixty-four bits per sample, the data in a two dimensional table corresponding to Range and Azimuth, each sample corresponding to a Range and Azimuth location;
• selecting a first FFT to provide a target ratio of pixel spacing to resolution;
• selecting a second FFT smaller than the first FFT;
• zero-padding the SAR data to fill the second FFT;
• encoding the SAR data through the second FFT to provide a plurality of pixels, each pixel having a Range and Azimuth location set, for each Range and Azimuth location set there is an associate Phase and Magnitude of the reflected energy, each pixel having sixty-four bits, thirty-two bits for a logarithm of Magnitude and thirty-two bits for an arctangent of Phase;
• converting the thirty-two bit logarithm Magnitude to a first eight-bit fixed value and the thirty-two bit arctangent of Phase to a second eight-bit fixed value;
• transferring the first and second eight-bit fixed values to a remote location;
• converting the first and second eight-bit values back to the thirty-two bit logarithm Magnitude and thirty-two bit arctangent of Phase;
• inverting the second FFT transformation at the remote location to restore the SAR data from the Magnitude and Phase as restored SAR data;
• zero-padding the restored SAR data to fill the first FFT;
• and
• transforming the zero-padded restored SAR data to provide a data set of points with the target ratio of pixel spacing to resolution.

A computer-readable medium on which is stored a computer program for a non-statistical method for compressing and decompressing complex SAR data derived from a reflected energy, the computer program comprising instructions which, when executed by a computer, perform the steps of:

• selecting a first FFT to provide a target ratio of pixel spacing to resolution;
• selecting a second FFT smaller than the first FFT;
• zero-padding the data to fill the second FFT;
• transforming the zero-padded data with the second FFT to provide at least one transfer frequency;
• transferring the at least one transfer frequency to a remote location;
• inverting the second FFT transformation at the remote location to restore the data from the transferred at least one transfer frequency as restored data;
• zero-padding the restored data to fill the first FFT;
• and
• transforming the zero-padded restored data to provide a data set of points with the target ratio of pixel spacing to resolution.

A computer-readable medium on which is stored a computer program for a non-statistical method for compressing and decompressing complex SAR data derived from a reflected energy, the computer program comprising:

• a compression routine including;
• an input routine operatively associated with an input device for receiving complex SAR data in the form of Video Phase History (VPH) data and a user specified target ratio of pixel spacing to resolution;
• a selection routine for selecting a first FFT based on the user specified target ratio and a second FFT smaller than the first FFT;
• a transformation routine for zero-padding the VPH data to fill the second FFT, transforming the zero-padded VPH data to provide at least one transfer frequency;
• and
• an output routine operatively associated with an output device to provide at least the transfer frequency;
• a decompression routine including;
• an input routine operatively associated with an input device for receiving the at least one transfer frequency from the compression routine;
• an invert transformation routine for restoring the VPH data from the transferred transfer frequency as restored VPH data;
• and
• an image processing routine for processing the restored VPH data with the first FFT to provide a data set of points with the target ratio of pixel spacing to resolution.