Inventors:
Herbert S. Kobayashi - Webster TX
Paul W. Shores - Houston TX
Patrick Rozas - Houston TX
Assignee:
The United States of America as represented by the Administrator of the
National Aeronautics & Space Administration - Washington DC
International Classification:
G01S 944
Abstract:
A microwave radar signal is generated (12) for transmission through an antenna (20). Before transmission, the signal is phase modulated (18) by 0. degree. or 90. degree. amounts during each alternate half-cycles of an intermediate frequency (IF) clock signal (26). After transmission and return, the signal is again phase modulated (18) the same amounts during each alternate half-cycles. The return phase modulated signal is mixed (24) with a leakage signal component of the microwave signal, leaving an IF doppler. The IF doppler signal may then be amplified (30), removing any requirement that direct current level signals be amplified and also removing the effect of detector noise from the doppler signal.