Accession Number : ADD017398

Title :   Method and Apparatus for Maintaining Linearity and Frequency Accuracy of an FM Chirp Waveform.

Descriptive Note : Patent, Filed 4 Apr 94, patented 27 Dec 94,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Martinez, Roger I ; Sanders, Michael L ; Ashton, John H

Report Date : 27 Dec 1994

Pagination or Media Count : 13

Abstract : A homodyne radar apparatus and method for performing radar cross-section measurement by maintaining the linearity and compensating for frequency drift of an FM chirp waveform produced by a YIG tuned oscillator. A digital computer uses a predetermined data look-up table of each YIG oscillator frequency characteristic in conjunction with a digital to analog converter to provide a compensating sweep signal to linearize the frequency output of the oscillator. The computer uses an analog to digital converter in conjunction with a reference circuit output to compare the actual YIG signal nulls resulting from the reference circuit to the nulls in a signal produced by a lab standard oscillator in the reference circuit to adjust start sample delay of the ADC and to correct any frequency drift evidenced by the difference in the null of the signal. (AN)

Descriptors :   *RADAR CROSS SECTIONS, *PATENTS, SIGNAL PROCESSING, LINEAR SYSTEMS, FREQUENCY MODULATION, WAVEFORMS, ACCURACY, VOLTAGE, DRIFT, RADAR EQUIPMENT, FAST FOURIER TRANSFORMS, RADAR SIGNALS, RADAR ANTENNAS, ANALOG TO DIGITAL CONVERTERS, CHIRP RADAR, FREQUENCY RESPONSE, DIGITAL COMPUTERS, RADIOFREQUENCY OSCILLATORS, YTTRIUM IRON GARNET, HOMODYNE RADIO RECEIVERS

Subject Categories : Active & Passive Radar Detection & Equipment
      Electrical and Electronic Equipment
      Computer Hardware

Distribution Statement : APPROVED FOR PUBLIC RELEASE