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Waveform synthesis for imaging and ranging applications

United States Patent

December 28, 2004
View the Complete Patent at the US Patent & Trademark Office
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Frequency dependent corrections are provided for Local Oscillator (LO) feed-through. An operational procedure filters LO feed-through effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver, unwanted energies, such as LO feed-through energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of LO feed-through can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.
Dubbert; Dale F. (Cedar Crest, NM), Dudley; Peter A. (Albuquerque, NM), Doerry; Armin W. (Albuquerque, NM), Tise; Bertice L. (Albuquerque, NM)
Sandia Corporation (Albuquerque, MN)
10/ 437,329
May 13, 2003
STATEMENT OF GOVERNMENT INTEREST The United States Government has rights in this invention pursuant to Department of Energy Contract No. DE-AC04-94AL85000 with Sandia Corporation.