Abstract: A pulse rate monitor comprises first and second units coupled by a cable. The first unit has a microwave ocillator that provides a pulsating DC signal in accordance with the pulse rate to the second unit which amplifies the signal. Since the first unit does not comprise microwave components other than the oscillator, it can be miniturized. The second unit also supplies power to the first unit.

Abstract: A calibration instrument for calibrating a continuous wave microwave doppler radar includes a piezoelectric sounder and means to energize the sounder to produce an acoustic signal to simulate motion of a body to the radar.

Abstract: An identification system comprising one or more tags and an interrogator. A tag is responsive to a radio frequency signal transmitted from the interrogator for phase modulating the signal alternately with a first frequency and a second frequency depending on a preselected code and for re-radiating the phase modulated signal back to the interrogator.

Abstract: A tag is receptive of two radio frequencies (RF signals) for mixing the two frequencies and radiating a signal which is either or both the sum and difference of the two RF frequencies. A uniquely identifiable tag includes, in addition to the mixer one or more filters for radiating a signal only when the sum or difference of the two signals is a pre-specified value or only when the RF signals are each of pre-selected values.

Abstract: A signal component separating circuit is responsive to a signal having a pulsing component and a reciprocating component for providing a signal corresponding to the pulsing component. The circuit includes first and second channels the outputs of which are coupled to respective inputs of a comparator circuit which produces the signal corresponding to the pulsing component of the input signal.Each of the channels includes a peak detection and holding circuit which includes a charging and discharging circuit. The second channel peak detection and holding circuit has a faster charging and discharging time than the first channel peak detection and holding circuit. The second channel peak detection and holding circuit attenuates the input signal more than the first channel peak detection and holding circuit. As a result the signal in the first channel is greater in amplitude than the signal in the second channel except when the pulses are present.

Abstract: A microwave cavity oscillator comprises a waveguide blocked at both ends, an active device enclosed in the waveguide and a dielectric powder or other fluid filling the remaining space in the waveguide. The microwave cavity oscillator is useful, for example, as in a discontinuity detector system.

Abstract: A frequency generator or filter which includes a signal source of simultaneous multiple frequencies, a voltage controlled oscillator (VCO), a circulator coupled between the signal source and frequency terminal of the VCO and a source of control voltage signals coupled to the control voltage terminal of the VCO. A control voltage corresponding to a desired one of the frequencies produced by the signal source is applied to the VCO causing it to produce a frequency approximating the desired frequency. Then the signal from the frequency source injection locks the VCO to exactly the desired frequency.

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 monolithic voltage controlled oscillator is fabricated on a single semiconductor body. The oscillator includes an FET and a varactor diode interconnected such that a voltage applied across the varactor modulates the oscillating frequency of the FET output.

Abstract: A signal of frequency value F.sub.IN is coupled to a discriminator and to one terminal of a voltage controlled oscillator (VCO) tuned to operate at a range of frequencies about F.sub.IN .div.N where N is a nonunity positive integer. The discriminator produces a voltage proportional to frequency F.sub.IN which is scaled and applied to a control terminal of the VCO to cause it to be tuned to approximately F.sub.IN .div.N. The signal of frequency F.sub.IN applied to the VCO causes it to be injection locked to frequency F.sub.IN .div.N.

Abstract: A vehicle identification system includes apparatus located on the vehicle for transmitting a continuous wave RF probe signal, a remote interrogator unit responsive to the probe signal for transmitting back thereto an interrogation signal. The apparatus on the vehicle transmits in response to the interrogation signal an identifying code. The probe signal may be further utilized in determining the speed of the vehicle.

Abstract: A doppler type speed sensor produces a doppler signal having a spectrum of frequencies including a frequency of peak amplitude corresponding to the actual speed of an object. The frequencies are supplied to a narrowband voltage tunable filter, the frequency bandwidth of which is continuously adjusted by a periodically reoccurring sweep signal applied thereto. The output of the filter is coupled to a peak detecting circuit which produces a pulse when the maximum amplitude signal is received thereat. The sweep signal and pulse are applied to the inputs of a sample-and-hold circuit to cause the sample-and-hold circuit to hold and produce a signal corresponding to the value of the peak frequency and therefore the speed of the object.

Abstract: A frequency memory system having a smart noise component is receptive of an RF burst signal of a given frequency and of relatively short duration for determining the frequency and storing a signal of amplitude indicative of the given frequency and for producing by means of a voltage controlled oscillator (VCO) a signal at the given frequency of relatively long duration. The stored signal and a signal for amplitude corresponding to the actual frequency produced by VCO are utilized to produce an error signal to correct any error in the frequency of the signal produced by the VCO relative to the given frequency. Since the VCO is not capable of immediately accurately tracking the input frequency, a smart noise generator produces a signal of random amplitude which is added to the error signal to cause the VCO to produce at least a frequency component of its output signal which is equal to that of the input RF burst signal.

Abstract: A radio frequency pulse generator for use in a pulsed radar transmitter includes a reference oscillator of one radio frequency, a second oscillator producing a different second radio frequency which differs from a multiple M of the first frequency by a given amount and a third oscillator which is injection locked by the second oscillator to produce a subharmonic frequency of the second frequency and, when not transmitting, is injection locked by the first oscillator to thereby produce its frequency.

Abstract: A microwave power limiter for generating an output RF signal of substantially constant power level in response to an input RF signal of varying power level comprises a single gate field effect transistor (FET). The FET is biased such that the RF power output variation is small compared to the input power variation in the saturation region. A number of FET cascaded stages may be utilized to reduce this power output variation. A small signal amplifier including a number of FET cascaded stages may be employed in the limiter to increase the power level to that gain or drive level compatible with the saturated FET stages.