Novariant, Inc.

Leland Stanford Junior University

Frank N Bauregger

Kurt R Zimmerman

Jamal Izadian

Per Kristian Enge

H Stewart Cobb

Dennis M Akos

Todd F Walter

In a local positioning system, a receiver is adapted for receiving signals from a land-based transmitter. The receiver includes an analog decorrelator for decorrelating the transmitted spread spectrum signals. A down converter connected with an antenna may be spaced away from other portions of the receiver. The down converter down converts received ranging signals and provides them to the remotely spaced receiver portions. A signal line connecting the down converter to the receiver may be operable to transmit any two or more of a reference signal provided to the down converter, the down converted intermediate frequency signals provided to the receiver, and power provided to the down converter. The receiver may be positioned adjacent to or as part of a land-based transmitter. By determining positions of two or more antennas, the location of the associated transmitter is determined.

Distributed radio frequency ranging signal receiver for navigation or position determination

In a local positioning system, augmentation of the land-based system is provided by receiving signals from a GNSS. The signals from the land-based positioning system have a code phase accuracy better than one wavelength of a carrier of the signals from the GNSS. Different decorrelation may be used for signals from a satellite than from a land-based transmitter, such as using a digital decorrelator for signals from the satellite and an analog decorrelator for signals from a land-based transmitter. The receivers may include both a GNSS antenna and a local antenna. The phase centers of the two antennas are within one wavelength of the GNSS signals from each other. The local antenna is sized for operation in the X or ISM-bands of frequencies. The GNSS antenna is a patch antenna where the microwave antenna extends away from the patch antenna in at least one dimension.

Multiple frequency antenna structures and methods for receiving navigation or ranging signals

Method and apparatus for reducing radio frequency interference (RFI) using a dual-element patch antenna [The antenna possesses two antenna elements [having distinct radiation patterns. Either element may be independently selected using a DC bias voltage. Diodes [connected to the elements serve to disable one element when the other is selected. In one selected mode, a nominal radiation pattern provides a broad, hemispherical shaped sensitivity that is designed for acquiring and tracking all navigation satellites above the horizon. This nominal radiation pattern, however, is susceptible to interference that is present near or below the horizon. The second selectable radiation pattern of the dual-element antenna has comparatively higher gain toward zenith, and lower gain at and below the horizon to mitigate interference. This combination of features is packaged in a single antenna unit that can be a direct replacement for existing antennas. The dual-element antenna unit has a low vertical profile and is suitable for mounting on high-speed moving vehicles.

Dual-element microstrip patch antenna for mitigating radio frequency interference

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Mountain View, CA, United States of America

Frank N Bauregger