John A Higbee

US Patent:

55215556, May 28, 1996

Filed:

Jul 25, 1994

Appl. No.:

8/279509

Inventors:

Daniel A. Tazartes - West Hills CA
John E. Higbee - Simi Valley CA
Jacque A. Tazartes - Beverly Hills CA
Juergen K. P. Flamm - Tarzana CA
John G. Mark - Pasadena CA

Assignee:

Litton Systems, Inc. - Woodland Hills CA

International Classification:

H03F 308

US Classification:

330308

Abstract:

An amplifier topology for receiving signals output from a fiber optic rotation sensor and producing voltages that may be processed to determine the rotation rate includes a photodiode for receiving an optical signal and producing a corresponding electrical photodiode output signal. An ultra low noise and ultra low capacitance differential input stage is connected to receive the photodiode output signal. An operational amplifier having low noise and ultra-wide bandwidth is connected to the ultra low capacitance differential input stage to receive the output signal therefrom as a driving signal and to produce a low noise output signal. The differential input stage comprises a first amplifier circuit that includes a first transistor connected to the photodetector to act as a first buffer having low noise, low capacitance and unity gain. The first amplifier circuit also includes a second transistor configured as a first voltage follower connected between the output of the first buffer and the operational amplifier to isolate the output of the first buffer from parasitic capacitive loading from a biasing network. The differential input stage further comprises a second a second amplifier circuit that includes a third transistor having an input connected to a reference potential, the third transistor acting as a second buffer having low noise, low capacitance and unity gain.

US Patent:

39433390, Mar 9, 1976

Filed:

Apr 29, 1974

Appl. No.:

5/465031

Inventors:

Ralph J. Koerner - Canoga Park CA
Milton G. Bienhoff - Canoga Park CA
Martin C. Henderson - Canoga Park CA
John E. Higbee - Santa Susana CA
Steve J. Koerner - Van Nuys CA

Assignee:

Canoga Controls Corporation - Canoga Park CA

International Classification:

G08G 1065
G08G 108

US Classification:

235 92TC

Abstract:

Apparatus for use in combination with multiple inductive loops for detecting metal objects, e. g. vehicles, in the immediate vicinity of each of said loops. Each loop may, for example, be a coil of wire buried in a roadway in a plane parallel to the roadway surface. A common oscillator circuit is operatively connected to each loop on a time shared basis with the frequency of oscillation at any time being determined by the inductance of the connected loop. The inductance in turn is dependent on whether or not a vehicle is over the loop. Successive scan cycles are defined with multiple loop phases occurring during each scan cycle. During each loop phase, a different one of the multiple loops is connected to the oscillator circuitry and during a "period measurement" portion of each loop phase, the loop frequency is monitored by digital circuitry including a loop counter which counts loop oscillator cycles and a duration counter which measures the time duration or period of a certain number of such loop oscillator cycles. The measured time duration (period) is then compared with an historical reference duration (accumulated over prior scan cycles) during a "calculation and storage" portion of each loop phase to ascertain whether the loop oscillator frequency has increased or decreased. The presence of a vehicle over the loop decreases loop inductance, increases loop frequency, and thus reduces the measured period.