Space variant signal processor
AssigneeThe United States of America as represented by the Secretary of the Army
InventorsDavid P. Casasent, Demetri Psaltis
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Abstract
A correlation method and apparatus for electrical signal transmission and ception of coded waveforms are disclosed which makes use of a coordinate transformation of the original waveform prior to transmission, effecting an inverse coordinate transformation upon reception and then correlating the resultant waveform with the original waveform. More particularly, the coordinate transformation and its inverse comprises a non-linear transformation preferably of the logarithmic type which when utilized in an electro-optical signal processor of a radar system, for example, provides Doppler invariant output data, as well as additional noise immunity.
Claims19
A method for processing and correlating two signal waveforms, comprising the steps of:
- generating a reference signal waveform;
- applying a coordinate transformation to said reference signal waveform;
- generating a carrier signal;
- transmitting the carrier signal modulated by said transformed signal waveform to a remote location;
- receiving and demodulating the transmitted signal waveform returned from the remote location;
- applying an inverse coordinate transformation with respect to the above mentioned coordinate transformation to the received signal waveform;
- correlating the inversely transformed received signal waveform with said reference signal waveform to obtain an output signal;
- and
- generating a representation of said output signal.
A signal processing system of a correlation type including electrical signal transmitting and receiving means wherein the improvement comprises:
- signal generator means in said transmitter means providing a reference signal;
- first coordinate transformation means in said transmitter means coupled to said signal generator means and being responsive to said reference signal to generate a signal therefrom having a predetermined non-linear coordinate transformation of the reference signal;
- carrier signal generating means in said transmitter means coupled to said first coordinate transformation means and being responsive to said signal having said predetermined non-linear coordinate transformation to generate a carrier signal which is modulated thereby and which is subsequently transmitted to an external location;
- means for receiving and demodulating a reflected return signal from said external location;
- second coordinate transformation means in said receiver means and being responsive to the received signal from said external location, said received signal corresponding to the transmitted signal having said non-linear coordinate transformation and being operable to generate a signal having an inverse coordinate transformation relative to said non-linear coordinate transformation;
- signal correlation means coupled to said reference signal and said signal having said inverse coordinate transformation for providing a correlation peak indicative of a predetermined data parameter;
- and
- means coupled to said signal correlation means for generating a representation of said predetermined data parameter.
Dependencies are inferred from the claim text.