Abstract: A microwave radar signal is generated (16) and split by a circular (20). A phase shifter (24) introduces a plurality of phase shifts into a first part of the split signal which is then transmitted (36) by antenna (34). A like plurality of phase shifts are introduced by the phase shifter into the return signal (40) from the target. The circulator delivers the phase shifted return signal and the leakage signal from the circulator to a mixer (44) which generates an i.f. signal output at the doppler frequency. The i.f. signal is amplified (46l ), filtered (54), counted (58) per unit of time and the result displayed (62) to provide indications of target sense and range rate. An oscillator (50) controls rate of phase shift in the transmitted and received signals and provides a time base for the counter. The phase shift magnitude increases may be continuous and linear or discrete functions of time.

Abstract: A system for deriving direct digital indications of frequency and phase difference between two incoming pulse trains adaptable for collision avoidance systems or the like.A pair of radar beams 152 and 152A are directed toward a target 153 and corresponding beams 154 and 154A returning therefrom are detected. A digital difference circuit 110 forms a pulse train 66 from the Doppler shift frequencies of each beam pair having a repetition rate functionally related to the difference in magnitude of the shift frequencies. Pulses from the pulse train are counted as a function of time. Visual indications thereof on display 144 are correlative to target position relative to beams 152 and 152A.

Abstract: A signal is transmitted from a first location to a remote second location where a target carrying a transponder is positioned. The transponder re-radiates the signal to the first location where it is received. A phase comparator generates from the transmitted and received signals a measurement of their phase difference which is functionally related to the distance between the first and second locations. In one embodiment, the transponder is a passive parametric oscillator, being powered by energy received from the transmitted signal, which generates and transmits a subharmonic of the transmitted signal.

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.

Abstract: Disclosed is a system for an orbital antenna means which is operated at a synchronous altitude to scan an area of a celestial body. The antenna means comprises modules which are operated by a steering signal in a repetitive function for providing a scanning beam over the area. The scanning covers the entire area in a pattern and the azimuth of the scanning beam is transmitted to a control station on the celestial body simultaneous with signals from an activated ground beacon on the celestial body. The azimuth of the control station relative to the antenna means is known and the location of the ground beacon is readily determined from the azimuth determinations.