Thomas Eugene Donahue

US Patent:

40400557, Aug 2, 1977

Filed:

Jul 15, 1974

Appl. No.:

5/488726

Inventors:

Thomas H. Donahue - Los Angeles CA
David E. Hammers - Los Angeles CA

Assignee:

International Telephone and Telegraph Corporation - New York NY

International Classification:

G01S 942

US Classification:

343 77

Abstract:

A digital compensator for radar transmitter instabilities for use in a digital MTI system. The I and Q coherent phase detector outputs are continuously monitored for phase, amplitude and timing instabilities and arithmetic correction signals are generated and applied to the digitized received signal values to compensate for these instabilities which are particularly characteristic of pulsed magnetron transmitters, for example.

US Patent:

39493989, Apr 6, 1976

Filed:

Dec 16, 1974

Appl. No.:

5/532842

Inventors:

Thomas H. Donahue - Los Angeles CA

Assignee:

International Telephone and Telegraph Corporation - New York NY

International Classification:

G01S 942

US Classification:

343 77

Abstract:

An instantaneous gain controlling system particularly for coherent (MTI) radar systems. A gain controllable intermediate frequency amplifier, a COHO, and a phase detector are shown along with an MTI canceller which itself includes a delay device and a differencer are shown. The delay device provides a full pulse repetition period of delay, and the differencer operates to subtract the coherent video at the phase detector output from the same signal train, one pulse repetition interval earlier, to provide MTI cancellation. The delayed video train is full wave rectified, passed through a threshold circuit and an adjustable gain video amplifier and used as a pulse-by-pulse gain controlling signal for the intermediate frequency amplifier. Large signal blocks are thus prevented from overloading the receiver channel with consequent spectral spreading and MTI cancellation degradation.