National Research Council of Canada

Brent Carlson

A method for timing aperture synthesis arrays comprising the steps of: (a) coupling a plurality of independent crystal oscillators, each of the plurality of independent crystal oscillators having a unique output frequency; (b) digitally synchronizing the plurality of independent crystal oscillators in phase; (c) combining the unique output frequencies; and (d) obtaining a stable digital reference signal for timing at least one remote radio device of the aperture synthesis array.

Stable scalable digital frequency reference

Methods and systems for synchronizing at least one remote local oscillator with a central local oscillator, comprising receiving a remote local oscillator signal from at least one remote local oscillator and a master local oscillator signal from the central local oscillator and in response determining a round-trip phase measurement of temporal delay variability of the duplex real-time link between the remote station and central station, measuring frequency vs. time of the remote local oscillator signal relative to the master oscillator, adjusting the measured frequency vs. time according to the round-trip phase measurement to remove effects of temporal delay variability over the duplex real-time link telemetry, digitally filtering the measured frequency to remove variations in frequency on timescales<10× the round-trip delay and that are known not to be intrinsically due to the remote local oscillator, generating a phase increment signal from the filtered measured frequency, receiving and adjusting the local oscillator signal according to the phase increment signal and in response generating a derived digital domain clock signal that tracks the master local oscillator signal and converting the derived digital domain clock signal to an ultra-low phase-noise time domain voltage clock signal.

System and method for remote digital time transfer

A digital clean-up oscillator and associated method are provided for cleaning jitter from a noisy clock signal, comprising receiving a reference clock oscillator signal and the noisy clock signal to be cleaned: measuring the frequency of the reference clock signal in the time domain of the noisy clock signal: filtering any frequency variations from the measured frequency of the reference clock signal on timescales shorter than a phase change interval Tau_clean over which jitter in the noisy clock signal is to be cleaned; generating a phase increment signal DDS_pinc based on the measured and filtered frequency of the reference clock signal: clocking the phase increment signal DDS_pinc with the reference clock signal for generating an output digital phase ramp signal φ_DDS(t) that tracks the frequency of the noisy clock signal with phase wander removed on timescales less than the phase change interval Tau_clean; and converting the output digital phase ramp signal φ_DDS(t) to an output jitter-cleaned time domain clock signal frequency locked to the noisy clock signal.

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Penticton, Canada

Brent Carlson