Abstract: Disclosed is a technique that can provide one or more countermeasures against spoofers. An antenna, movable in space, is used to receive space vehicle (SV) signals that appear to be associated with a plurality of space vehicles of a global navigation satellite system (GNSS). SV signals are identified that have similar signal power and/or phase signatures that respectively appear to be associated with at least a first space vehicle and a second space vehicle of the GNSS. An existence of a spoofer is identified based at least in part on the identification of SV signals that have similar signal power and/or phase signatures that respectively appear to be associated with at least the first space vehicle and the second space vehicle of the GNSS.

Abstract: Disclosed is a technique that can provide one or more countermeasures against spoofers. A beamformer can control an antenna pattern of a CRPA to generate a survey beam. The survey beam is swept across space to determine a characteristic signature based on carrier-to-noise ratios (C/No) for particular space vehicle signals. Matching C/No signatures can be used to identify the existence of spoofers and invoke a countermeasure, such as nulling.

Abstract: Disclosed is a technique that can provide one or more countermeasures against spoofers. A direction from which a spoofing attack occurs is identified. A beamformer can control an antenna pattern of a CRPA to null out signals from that direction, which can assist a GNSS receiver to avoid error induced by the spoofing attack. Further, after two or more observations, the location of the spoofer can be identified.

Abstract: Disclosed is a technique that can provide one or more countermeasures against spoofers. A beamformer can control an antenna pattern of a CRPA to generate a survey beam. The survey beam is swept across space to determine a characteristic signature based on carrier-to-noise ratios (C/No) for particular space vehicle signals. Matching C/No signatures can be used to identify the existence of spoofers and invoke a countermeasure, such as nulling.

Abstract: Disclosed is a technique that can provide one or more countermeasures against spoofers. A direction from which a spoofing attack occurs is identified. A beamformer can control an antenna pattern of a CRPA to null out signals from that direction, which can assist a GNSS receiver to avoid error induced by the spoofing attack. Further, after two or more observations, the location of the spoofer can be identified.

Abstract: Disclosed is a technique that can provide one or more countermeasures against spoofers. A beamformer can control an antenna pattern of a CRPA to generate a survey beam. The survey beam is swept across space to determine a characteristic signature based on carrier-to-noise ratios (C/No) for particular space vehicle signals. Matching C/No signatures can be used to identify the existence of spoofers and invoke a countermeasure, such as nulling.

Abstract: Disclosed is a technique that can provide one or more countermeasures against spoofers. A direction from which a spoofing attack occurs is identified. A beamformer can control an antenna pattern of a CRPA to null out signals from that direction, which can assist a GNSS receiver to avoid error induced by the spoofing attack. Further, after two or more observations, the location of the spoofer can be identified.

Abstract: Apparatus and methods spread input symbols for transmission in multiple dimensions. When input symbols are spread over time, frequency, and code space, the resulting symbols exhibit good immunity to interference. In one embodiment, a system with a multi-tone outer code/modulation and a direct sequence spread spectrum (DSSS) inner code/modulation provides good communications performance characteristics and can be efficiently implemented.

Abstract: A method and system for performing sequence time domain reflectometry over a communication channel to determine the location of line anomalies in the communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over an optical channel. The system receives one or more reflection signals over the optical channel and performs reflection signal processing on the reflection signal. In one embodiment, the optical reflection is transformed to an electrical signal and correlated with the original sequence signal to generate a correlated signal. The time between the start of the reflection signal and a subsequent point of correlation and the rate of propagation reveals a line anomaly location. In one or more embodiments sequence signal time domain reflectometry occurs during data transmission.

Abstract: A method and system for performing sequence time domain reflectometry over a communication channel to determine the location of line anomalies in the communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over an optical channel. The system receives one or more reflection signals over the optical channel and performs reflection signal processing on the reflection signal. In one embodiment, the optical reflection is transformed to an electrical signal and correlated with the original sequence signal to generate a correlated signal. The time between the start of the reflection signal and a subsequent point of correlation and the rate of propagation reveals a line anomaly location. A circulator, beam splitter, or any other similar device may direct the reflection signal to the apparatus configured to perform reflection signal processing.

Abstract: A method and apparatus is disclosed for adaptively determining threshold values in a decision device, such as a decision slicer. In one embodiment, a slicer receives one or more updated threshold values during operation to adaptively accommodate changes in the received signal or the channel that may occur over time. The updated threshold value is based on a MIN value and a MAX value. The MIN values represent a value related to a recently received input that was determined to qualify for a particular slicer output and was less than the particular slicer output value. The MAX values represent a value related to a recently received input that was determined to qualify for a particular slicer output and was greater than the particular slicer output value. In one embodiment, the MAX and MIN value computation is based on scaling factors that dampen the rate of change of the threshold value.

Abstract: A method and apparatus is disclosed for adaptively determining threshold values in a decision device, such as a decision slicer. In one embodiment, a slicer receives one or more updated threshold values during operation to adaptively accommodate changes in the received signal or the channel that may occur over time. The updated threshold value is based on a MIN value and a MAX value. The MIN values represent a-value related to a recently received input that was determined to qualify for a particular slicer output and was less than the particular slicer output value. The MAX values represent a value related to a recently received input that was determined to qualify for a particular slicer output and was greater than the particular slicer output value. In one embodiment, the MAX and MIN value computation is based on scaling factors that dampen the rate of change of the threshold value.

Abstract: A method and system for performing sequence time domain reflectometry over a communication channel to determine the location of line anomalies in the communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over an optical channel. The system receives one or more reflection signals over the optical channel and performs reflection signal processing on the reflection signal. In one embodiment, the optical reflection is transformed to an electrical signal and correlated with the original sequence signal to generate a correlated signal. The time between the start of the reflection signal and a subsequent point of correlation and the rate of propagation reveals a line anomaly location. In one or more embodiments sequence signal time domain reflectometry occurs during data transmission.

Abstract: A method and system for performing sequence time domain reflectometry to determine the location of line anomalies in a communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over a channel. The system receives one or more reflection signals, and performs reflection signal processing on the reflection. In one embodiment, the reflection signal is correlated with the original sequence signal to generate a correlated signal. The system determines a time value between the start of the reflection signal and the subsequent points of correlation to determine a location of a line anomaly. In one embodiment preprocessing and post-processing occurs to counter the effects of a communication device, such as a DMT modulator/demodulator. In one embodiment sampling of the sequence and reflection signal may occur at different times or at a different phase to provide greater resolution of the line anomaly location.

Abstract: A method and system for performing sequence time domain reflectometry over a communication channel to determine the location of line anomalies in the communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over an optical channel. The system receives one or more reflection signals over the optical channel and performs reflection signal processing on the reflection signal. In one embodiment, the optical reflection is transformed to an electrical signal and correlated with the original sequence signal to generate a correlated signal. The time between the start of the reflection signal and a subsequent point of correlation and the rate of propagation reveals a line anomaly location. A circulator, beam splitter, or any other similar device may direct the reflection signal to the apparatus configured to perform reflection signal processing.

Abstract: A method and apparatus is provided for processing a signal to remove or reduce the unwanted effects of transmission through the transmission line. To reverse, negate or counter the attenuating properties of transmission through a transmission line the method and apparatus described herein determines the amount of amplification or a gain value required to restore one or more aspect of the signal to a desired or a pre-transmission level. Characterization of the line, based on the gain value, determines one or more filter coefficients. Based on the one or more coefficients, a filtered modifies the signal to reverse the effects of the channel. In one embodiment the peak value or an average magnitude of the received signal is detected to determine the gain value. Dampening may optionally be included to limit the amount of filter modification that may occur on the signal in a clock cycle.

Abstract: A method and system for performing sequence time domain reflectometry to determine the location of line anomalies in a communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over a channel. The system receives one or more reflection signals, and performs reflection signal processing on the reflection. In one embodiment, the reflection signal is correlated with the original sequence signal to generate a correlated signal. The system determines a time value between the start of the reflection signal and the subsequent points of correlation to determine a location of a line anomaly. In one embodiment preprocessing and post-processing occurs to counter the effects of a communication device, such as a DMT modulator/demodulator. In one embodiment sampling of the sequence and reflection signal may occur at different times or at a different phase to provide greater resolution of the line anomaly location.