Abstract: An interference signal canceling system for communications protection is described for canceling interference signals from earth station received signals using a two input adaptive cancellation network. The present invention addresses terrestrial, co-channel and adjacent satellite interference sources resulting from emitting, isolated, frequency re-use and polarized sources. Main and auxiliary signals are derived directly or by coherent conversion to intermediate frequency using an auxiliary antenna, cross-polarized feed, or auxiliary squinted feed. Filters set receive and canceling bands. Cancellation combines the main signal with a phase, amplitude and time modulated sample of the auxiliary signal. A receiver correlates the auxiliary signal with a sample of the combined output to minimize interference. A control drives the modulator from internal measurements, or satellite receiver measurements, i.e., BER, C/No, SNR, etc., or both.

Abstract: An interference signal canceling system for communications protection is described for canceling interference signals from earth station received signals using a two input adaptive cancellation network. The present invention addresses terrestrial, co-channel and adjacent satellite interference sources resulting from emitting, isolated, frequency re-use and polarized sources. Main and auxiliary signals are derived directly or by coherent conversion to intermediate frequency using an auxiliary antenna, cross-polarized feed, or auxiliary squinted feed. Filters set receive and canceling bands. Cancellation combines the main signal with a phase, amplitude and time modulated sample of the auxiliary signal. A receiver correlates the auxiliary signal with a sample of the combined output to minimize interference. A control drives the modulator from internal measurements, or satellite receiver measurements, i.e., BER, C/No, SNR, etc., or both.

Abstract: A digital signal processing system that produces an adaptive cancellation arrangement which nulls out all types of concurrent interference and/or jamming signals received by a Global Positioning System (GPS) or spread spectrum receiver from diverse antennas. The present invention uses a unique adaptive interference suppression technique to convert and digitize the analog input signals, and numerically modulate the data to produce effective cancellation of interference signals by nulling while preserving the multiple underlying spread spectrum signals. The invention generates digital and analog output signals which contain a reduced amount of interference. In the present arrangement, orthogonal components of the composite received signal are separated by the receive antenna arrangement and adjusted in the digital network between the antenna and receiver in phase and amplitude to optimally cancel components.

Abstract: A selective or tailored system for denying global positioning satellite (GPS) signal reception to unauthorized GPS receivers yet enabling authorized receivers to maintain access to the GPS system. The invention includes two basic units, the first being a tailored jamming unit which radiates an encoded denial or jamming waveform and the second being one or more receiver units including an interference or jamming signal suppression system which allows GPS user equipments to decode and suppress the jamming signal and receive the GPS satellite signal in the denial environment. The receiver unit decodes the encoded jamming signals. The jamming or denial signals, in its simplest form, employs a bi-polarization keying (BPK) defined as synchronously switching and radiating between two (or more) polarization states (or radiators) at a near 100-percent denial duty-cycle.

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.