US 5,712,641 AGranted

Interference cancellation system for global positioning satellite receivers

AssigneeElectro-Radiation Incorporated

InventorsMario M. Casabona, Murray W. Rosen, George A. Silverman

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Abstract

An adaptive polarization cancellation arrangement which nulls out all types of concurrent interference signals received by a Global Positioning System (GPS) receiver from antenna mainlobe and sidelobe situated sources. The orthogonally polarized components of the composite received signal are separated by the receive antenna arrangement and adjusted in the polarization feed adapter network between the antenna and GPS receiver to optimally cancel components. The antenna and installation arrangement creates a polarization filter relative to interference sources which changes their apparent polarization orientation and supports adaptive discrimination based on dissimilar polarization characteristics relative to the desired signals. The orthogonal received signal components from the GPS satellite constellation and from interference sources are combined to adaptively create cross-polarization nulls that adequately attenuate interference sources while slightly modifying the GPS received signals. The present network can also improve GPS signal levels and signal to noise ratio by polarization optimization or matching in noninterference environments.

Claims15

Dependent claims

A system for suppressing interference and jamming signals for a global positioning satellite system (GPS) receiver for receiving GPS transmissions in at least one of two L-band frequencies L1 and L2, the system comprising,

antenna means for receiving at least one of the GPS L1 and L2 signals and any inband interference or jamming signals and dividing the received signals into two orthogonally polarized antenna output signal components for each of the L1 and L2 frequencies;
polarimeter circuitry connected to said antenna means for receiving the orthogonally polarized antenna output signal components and for shifting the phase of the two orthogonally polarized antenna output signal components to obtain a polarimeter output signal wherein said polarimeter circuitry comprises,
a first variable phase shifting stage for receiving the two orthogonally polarized antenna output signal components and for shifting the phase of said orthogonally polarized antenna output signal components in accordance with first phase shift control signals from an adaptive phase control means,
a first hybrid junction for receiving the phase-shifted components from said first variable phase shifting stage and for combining the phase-shifted components to produce a pair of first hybrid junction output signals,
a second variable phase shifting stage for receiving said pair of first hybrid junction output signals and for shifting the phase of said pair of first hybrid junction output signals in accordance with second phase shift control signals from said adaptive phase control means, and
a second hybrid junction for receiving the phase-shifted components from said second variable phase shifting stage and for combining the phase-shifted components to obtain said polarimeter output signal;
adaptive phase control means connected with said first and second variable phase shifting stages for providing first and second phase shift control signals for repetitively adjusting the phase shifting in accordance with the polarimeter output signal until the polarimeter output signal is at a minimum representing at least one of the received L1 and L2 signals with any interference or jamming signals suppressed.

4 more elements

antenna means for receiving at least one of the GPS L1 and L2 signals and any inband interference or jamming signals and dividing the received signals into two orthogonally polarized antenna output signal components for each of the L1 and L2 frequencies;
polarimeter circuitry connected to said antenna means for receiving the orthogonally polarized antenna output signal components and for shifting the phase of the two orthogonally polarized antenna output signal components to obtain a polarimeter output signal,
wherein said polarimeter circuitry comprises a first pair of phase shifters for receiving and phase shifting the orthogonally polarized antenna output signal components, a first 90-degree hybrid junction coupled to said first pair of phase shifters, a second pair of phase shifters for receiving and phase shifting the outputs of said first hybrid junction, a second 90-degree hybrid junction coupled to said second pair of phase shifters, wherein said polarimeter output signal is provided at a difference (A) port of said second hybrid junction;
adaptive phase control means connected with said first and second pair of phase shifters for repetitively adjusting the phase shifting in accordance with the polarimeter output signal until the polarimeter output signal is at a minimum representing at least one of the received n1 and L2 signals with any interference or jamming signals suppressed.

1 more element

antenna means for receiving at least one of the GPS L1 and L2 signals and any inband interference or jamming signals and dividing the received signals into two orthogonally polarized antenna output signal components for each of the L1 and L2 frequencies, wherein said antenna means comprises a pair of patch antennas, each patch antenna a conductive portion of rectangular shape and having one length greater than its other length (D2), each patch antenna positioned in non-overlying adjacent relationship and oriented orthogonally with respect to each other such that said one length (D1) of one patch electrode is substantially perpendicular to said one length (D1) of said other patch electrode, each patch antenna having a pair of output leads, wherein each of the orthogonally polarized antenna output signal components of one of the L1 and L2 frequencies is provided on a first output lead from one of the patch antennas and a first output lead from the other patch antenna;
polarimeter circuitry connected to said antenna means for receiving the orthogonally polarized antenna output signal components and for shifting the phase of the antenna output signal components to obtain a polarimeter output signal;
adaptive phase control means connected with said polarimeter circuitry for repetitively adjusting the phase shifting of said polarimeter circuitry in accordance with the polarimeter output signal until the polarimeter output signal is at a minimum representing at least one of the received L1 and L2 signals with the interference or jamming signal suppressed.

Dependencies are inferred from the claim text.

Facts

Application: 08/608,493Filed 28 Feb 1996
Granted: 27 Jan 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01S 19/21
Receivers: interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
G01S 19/32
Receivers: multimode operation in a single same satellite system, e.g. GPS L1/L2
H04B 7/10
Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas: polarisation diversity; Directional diversity
H04B 7/18513
Systems using a satellite or space-based relay: transmission in a satellite or space-based system