Abstract: An enemy radar or transmitter transmits a signal at frequency f1. A tag on a friendly forces target receives frequency f1 and, in response thereto, transmits a signal at frequency f2.noteq.f1 modulated by a code unique to the tag. A friendly forces receiver, in response to receiving frequency f2 provides an indication that (a) the tag has received frequency f1, meaning the enemy is operating in the area, and (b) which specific tag has received a signal at frequency f1. The friendly forces can then take appropriate action.

Abstract: The totally passive object identification system and method involves the use of a radiometer to produce a signal corresponding to the radiation pattern generated by an object of interest in the frequency band to which the radiometer is sensitive, and involves comparing the produced signal with a signal corresponding to a given class of objects. The comparator produces a signal indicative of correspondence or a lack of correspondence between the object of interest and the given class of objects.

Abstract: A heart rate monitor for use where direct contact with a patient cannot be made utilizes two continuous radio frequency (RF) signals, one of relatively low frequency and one of relatively high frequency directed toward the patient whose heart is to be determined. Doppler shifted signals are reradiated by the patient back to the monitor. The reradiated low RF signal has doppler components due to bodily motion caused by respiration and heartbeat. The reradiated high RF signal has doppler components due to patient bodily movement caused by respiration. Doppler components due to heartbeat if any, are of substantially lower value than those associated with the low RF signal. The heart rate monitor includes a difference amplifier which effectively subtracts the doppler signal associated with the high RF frequency from the doppler signal associated with the low RF frequency to obtain a signal which contains only components due to the heartbeat of the patient.

Abstract: A frequency memory module responsive to an input relatively short duration RF burst signal of center frequency f for producing an output signal at center frequency f for a relatively long duration includes a narrow band filter tuned to pass frequency f which is receptive of the input signal, an amplifier connected to the output of the filter and feedback means connected from the output of the amplifier to the input of the filter. Because of the feedback the frequency memory module sustains oscillations at frequency f long after the input pulse is removed from the filter.

Abstract: A system for measuring wheel wear of a railroad vehicle includes a first speed measuring device, such as a microwave doppler speed sensor for measuring speed of the vehicle independent of wheel rotation rate, a second speed measuring device for measuring vehicle speed in terms of wheel rotation rate and a comparison device for measuring the difference of the two speed signals over time to therefore provide a signal indicative of wheel wear.

Abstract: A method and means for translating frequencies, as for example, to correct a frequency error .DELTA.f.sub.d introduced into a carrier signal of frequency f.sub.c, comprising means for dividing the resultant signal frequency (f.sub.c +.DELTA.f.sub.d) by N, resulting in a divided-down frequency (f.sub.c /N+.DELTA.f.sub.d /N), with .DELTA.f.sub.d being reduced to .DELTA.f.sub.d /N, and then heterodyning the divided-down frequency with signal of frequency (f.sub.c +f.sub.c /N) to produce a resultant signal of frequency (f.sub.c +.DELTA.f.sub.d /N), the frequency error remaining at its low, divided level .DELTA.f.sub.d /N.

Abstract: A doppler radar of the type normally used to measure relative speed between a transmitter and a reflector is mounted so that its antenna is directed toward the surface to be measured. The radar is coupled to a means for de-emphasizing the doppler shift frequencies of the return signal associated with the speed of the vehicle and emphasizing the lower frequency components of the back scattered signal. The energy contained in these components provides an indication of the roughness of the surface which is in relative motion to the radar.

Abstract: A reflector that reflects a microwave signal as a function of temperature is implanted within living tissue of a human. A microwave signal is transmitted to the reflector via an applicator in contact with the skin of the human. A portion of the signal reflected from the reflector is coupled via the applicator to a meter that provides an indication of the temperature of the reflector.

Abstract: A predetermined delay is provided for a microwave input signal by a delay line having a frequency divider circuit including a negative resistance semiconductor device responsive to the microwave input signal and a D.C. bias voltage. The frequency divider circuit converts the input signal at frequency f.sub.1, to a signal at a frequency, f.sub.2, within the operating range of an acoustic delay device coupled to the frequency divider circuit. A frequency multiplier circuit coupled to the acoustic delay device multiplies the frequency, f.sub.2, of the delayed signal from the acoustic device to the frequency, f.sub.1, of the input signal.