California Microwave, Inc.

John E Altstatt

Drew R Lance

John A Bush

A double-balanced mixer device including a planar substrate selectively plated on both sides to form certain mixer component parts and including a pair of quarter wavelength narrow strips extending from the component parts which form one of the balanced lines, such strips having their distal ends shorted together to provide an output terminal at which an IF signal may be taken. The quarter wavelength strips provide a low impedance path for IF signals but effectively block RF signals.

Double-balanced mixer

A low noise discriminator circuit having particular utility for use in determining the spectral purity characteristics of an rf signal source and comprising, in addition to standard discriminator components, a down-locked reference signal source including a voltage-controlled signal generator for developing a reference signal and a corresponding train of signal pulses, a stabilizing voltage-controlled oscillator which responds to the discriminator error signal and generates a stabilizing signal having a frequency at least an order of magnitude greater than the frequency of the reference signal, and a sampling phase detector which samples the stabilizing signal at the signal pulse frequency and develops a control signal which is fed through a feed-back loop to stabilize the reference signal generator.

FM discriminator having low noise characteristics

A threshold extension device for use in a frequency modulation demodulator circuit to minimize effects of impulse noise, usually referred to as 'clicks', which normaly appear in the demodulated output signal, and including a delay line for delaying the demodulated signal, a follow and hold circuit for selectively omitting the click impulses from the delayed signal, a detector for detecting the occurrence of an event which will give rise to a click impulse in the demodulated signal, and a detector driven control signal generator for controlling operation of the follow and hold circuit.

Frequency-modulation demodulator threshold extension device

An improved squelch circuit for FM demodulators including a low pass filter for filtering out-of-band noise from the demodulator output signals, a delay line for time delaying the filtered signals, a gate for selectively passing the filtered demodulated output signals to an output terminal, and a control circuit for controlling the gate. The control circuit includes a high pass filter for passing the out-of-band noise in the demodulated signals, a detector for detecting the noise level of the noise passed by the high pass filter, and a comparator for comparing the detected out-of-band noise level to a reference to develop a gate control signal which causes the gate to be opened when the out-of-band noise level is relatively low and to be closed when the out-of-band noise level is relatively high.

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Palo Alto, CA, United States of America

John E Altstatt