Westinghouse Electric Corporation

Northrop Grumman Systems Corporation

Norman G Matthews

Michael M Driscoll

John L Nugent

Christopher R Vale

John P Muhlbaier

Grant H Watkins

Aldez C Hazzard

Karl M Metzger

George C Rush

A crystal oscillator having a crystal filter with multiple crystals in a ladder configuration, resonant at a desired operating frequency. An oscillatory signal loop feedback path includes a voltage controlled phase shifter operable to shift the phase of the signal in the feedback loop in response to an applied control voltage. The feedback loop also includes a loop phase shift circuit to ensure that the feedback signal is a multiple of 360&#xb0;, and a band pass mode selection circuit for eliminating unwanted frequencies.

Crystal oscillator with wide tuning range

A low cost direct frequency synthesizer is structured to operate with moderate bandwidth, good noise performance, superior spurious performance, and fast switching. The direct frequency synthesizer employs a starter frequency signal f.sub.o (33-1) and a set of LO frequency signals f.sub.1 through f.sub.n (35-1) spaced from each other by a frequency increment .delta.. A mixer circuit (34-1) generates a product of the starter frequency signal and the LO frequency signals. A divider (31-1) has a divider ratio equal to N. The number of LO frequency signals is equal to or less than N. The starter frequency f.sub.o has a value equal to .delta. times (N+x) where x is equal to 0 or a positive integer. The LO frequency f.sub.1 has a value equal to (N+1)f.sub.o. An intermediate nonswitchable band pass filter (36-1) passes a difference portion of the mixer product to the divider, and a nonswitchable output band pass filter (38-1) receives an output from the divider to generate a moderate bandwidth output.

Direct frequency synthesizer having moderate bandwidth

An arrangement of crystal resonators that provides significantly reduced net resonator vibration sensitivity by arranging the crystallographic axes of some of the resonators to have antiparallel relationship, without regard to the acceleration sensitivity vector of any of the crystal resonators.

Low vibration sensitivity crystal resonator arrangement

A crystal-controlled oscillator operable at a direct UHF frequency includes an amplifier having a feedback circuit formed from an SC-cut crystal and an impedance network. The impedance network provides an impedance load for the cyrstal, and the values of the individual components forming the impedance network are selected to provide an overall inductive load for the SC-cut crystal. Inductively loading the cyrstal permits the crystal to oscillate at the C mode or UHF frequency mode, and prevents unwanted crystal oscillation at the B mode or VHF mode.

UHF crystal oscillator

A signal generator for high level low noise signals in which the preferred embodiment of the invention utilizes the output signal of a low noise crystal oscillator as a fundamental reference signal. The fundamental reference signal is multiplied to generate a series of coherent reference signals. Additionally, one of the coherent reference signals is coupled as an input signal to a divide circuit to generate at the output of the divide circuit a plurality of coherent low frequency reference signals. The coherent reference signals and the low frequency coherent reference signals are utilized by a synthesizer to generate a plurality of coherent signals having a frequency determined by the synthesizer. The output signal of the synthesizer is combined with one or more of the reference signals to generate the microwave output signal which is stepped from a minimum to a maximum value in equal increments.

Growing community of inventors

Sparks, MD, United States of America

Norman G Matthews