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: A vehicle velocity sensing system is disclosed which includes a doppler velocity sensor (10, 12) and means for reducing spurious signal components in the output of the sensor. An accelerometer (30, 32) is mounted so as to sense vehicle accelerations along the boresight of the doppler velocity sensor. A processor (34, 36) processes the output of the accelerometer to provide a signal which corresponds essentially to the spurious components of the output of the doppler radar velocity sensor. A signal combiner (38, 40) combines the output of the processor with the output of the doppler velocity sensor to derive a corrected output signal which is more closely indicative of the velocity of the vehicle.

Abstract: A Doppler radar is adapted to respond only to walking human targets by prding means to detect the frequency modulation of the Doppler signals caused by the oscillatory body movements of such walking targets. A frequency locked loop frequency modulation detector is provided for efficient detection of this so-called step frequency modulation, and the detected step frequencies are split into several bands representing targets walking at different step rates. Circuitry is shown for adapting this technique to continuous wave radars or range gated radars.

Abstract: Optical detection apparatus is provided which includes a coherent light sce for generating a beam of coherent light. The apparatus further includes a unitized or discrete optical component which receives the generated beam, and projects light thereof which has a particular polarization characteristic into a specified environment. The optical component also functions to receive or absorb light from the environment which has the particular polarization characteristic, and to directably reflect light from the environment which does not have the polarization characteristic. A lens or other light collecting device focuses light reflected by the discrete optical component upon a light detection element. A light conducting path is provided between the coherent light source and the light detecting element to enable generated coherent light to be mixed with the reflected light upon the light detecting element to provide data signals which indicate the presence of an object in the environment.