A controller is configured to control the adaptive notch filter and to execute a search technique (e.g., artificial intelligence (AI) search technique) to converge on filter coefficients and to recursively adjust the filter coefficients of the adaptive notch filter in real time to adaptively adjust one or more filter characteristics (e.g., maximum notch depth or attenuation, bandwidth of notch, or general magnitude versus frequency response of notch).

A round-trip, spread-spectrum navigation and locating system achieves high capacity and large processing gains in one-to-many and many-to-one configurations using round-trip signaling with frequency division based upon precise responding device carrier frequency offsets. Reduced cross-correlation is achieved by assigning these very small disparate frequency offsets to replies from interrogated devices so that the long-term correlation between disparate reply sequences is reduced almost to that of random noise of equivalent energy. The invention supports simultaneous interrogation of multiple responding devices, which responding devices respond essentially simultaneously at a fixed delay after receiving the query. The originating and/or responding devices may be fixed or mobile, permanently or temporarily deployed, terrestrial, airbourne or space-based with any source of power including batteries and solar without limitation. The signaling may be electromagnetic or acoustic with the potential for under-water use.

Method of reducing multipath effects on phase measurements, including receiving radio signals with different pseudo-random codes transmitted by at least four base stations, each at particular frequency received by one channel; measuring delay difference and phase difference from different pairs of base stations; calculating a current position of the receiver based on the measured phase differences and delay differences, wherein the base stations differ in pseudo-random codes at same frequencies or differ in carrier frequency or polarization type if using the same pseudo-random codes, and wherein a number of channels in the receiver exceeds a number of channels needed for the calculating of the current position; detecting anomalous jumps in phase of one or more channels, based on first or second derivative of the phase, as being indicative of multipath signal reception; removing those channels from calculation of current position; and calculating current position based on remaining channels.

Sets of digital samples associated with received wireless signals are received, each of the sets of digital samples corresponding to a particular RF path. The sets of digital samples are provided to a plurality of pipelines, each of the plurality of pipelines including a plurality of stages, each of the plurality of stages including one or more digital logic circuits. Sets of interconnect data are generated by the plurality of pipelines based on the sets of digital samples, the sets of interconnect data including at least one accumulating value. The sets of interconnect data are passed between adjacent pipelines of the plurality of pipelines along a direction. A result is generated by a last pipeline of the plurality of pipelines based on the at least one accumulating value.

The present disclosure relates to a method for synchronizing an encoded signal, in particular a GNSS signal. The method comprises receiving an input signal comprising a first signal component and a second signal component, wherein a sequence of N bits of the first signal component and a sequence of M bits of the second signal component are known a priori. The method further comprises determining a first logical sequence based on a plurality of cross-product operations formed between pairs of vectors obtained from a plurality of received symbols of the first signal component and the second signal component of the received input signal. The method also comprises identifying a position of a second logical sequence within the first logical sequence, the second logical sequence resulting from logical operations performed between at least a part of the known sequence of N bits of the first signal component and a corresponding number of bits of the known sequence of M bits of the second signal component in order to synchronize to a frame of the received input signal.

A round-trip, spread-spectrum navigation and locating system achieves high capacity and large processing gains in one-to-many and many-to-one configurations using round-trip signaling with frequency division based upon precise responding device carrier frequency offsets. Reduced cross-correlation is achieved by assigning these very small disparate frequency offsets to replies from interrogated devices so that the long-term correlation between disparate reply sequences is reduced almost to that of random noise of equivalent energy. The invention supports simultaneous interrogation of multiple responding devices, which responding devices respond essentially simultaneously at a fixed delay after receiving the query. The originating and/or responding devices may be fixed or mobile, permanently or temporarily deployed, terrestrial, airbourne or space-based with any source of power including batteries and solar without limitation. The signaling may be electromagnetic or acoustic with the potential for under-water use.

Embodiments of the present disclosure are directed to a jam resistant signal. The signal is transmitted from a terminal to a satellite. The signal may include two waveform components. The first waveform component includes a Frequency Division Duplex (FDD) wideband Direct Spread Spectrum (DSSS) waveform. The FDD wideband DSSS waveform may include one or more spectrally notched portions. At least one of the spectrally notched portions may be for the second waveform component. The second waveform component includes an FDD narrowband waveform.

A time transfer modem includes a radio frequency integrated circuit (RFIC), a radio frequency (RF) front end, and processing circuitry. The RF front end is configured to receive and up-convert an input for time transfer with a remote station to generate an up-converted timing signal centered at a select frequency that is outside of a frequency range of interest but within an operational frequency range of the RFIC. The RF front end may also be configured to attenuate, via a pre-selection filter, up-converted adjacent signals to generate a filtered timing signal at the select frequency. The RFIC may be configured to down-convert and digitize the filtered timing signal to generate a digitized timing signal for signal processing by the processing circuitry to determine a clock difference between a local clock signal and the digitized timing signal that originated from the remote station.

A time transfer modem includes a radio frequency integrated circuit (RFIC), a radio frequency (RF) front end, and processing circuitry. The RF front end is configured to receive and up-convert an input for time transfer with a remote station to generate an up-converted timing signal centered at a select frequency that is outside of a frequency range of interest but within an operational frequency range of the RFIC. The RF front end may also be configured to attenuate, via a pre-selection filter, up-converted adjacent signals to generate a filtered timing signal at the select frequency. The RFIC may be configured to down-convert and digitize the filtered timing signal to generate a digitized timing signal for signal processing by the processing circuitry to determine a clock difference between a local clock signal and the digitized timing signal that originated from the remote station.

A controller is configured to control the adaptive notch filter and to execute a search technique (e.g., artificial intelligence (AI) search technique) to converge on filter coefficients and to recursively adjust the filter coefficients of the adaptive notch filter in real time to adaptively adjust one or more filter characteristics (e.g., maximum notch depth or attenuation, bandwidth of notch, or general magnitude versus frequency response of notch).