Abstract: A method of calculating a transmitter and dispersion penalty for predicting optical link signal quality includes providing an optical link; capturing an averaged eye, using an optical test signal sequence to drive the transmitter with an oscilloscope receiver having an oscilloscope bandwidth as available; and from the averaged eye, capturing histograms A1; capturing a non-averaged eye using an optical test signal sequence to drive the transmitter, and from the non-averaged eye, capturing histograms B1; de-convolving histograms A1 from histograms B1; filtering waveform from step 1), convolve the filtered waveform from step 4) with the estimate of the noise from 3); and calculating “soft” TDP based on the probability distribution function.

Abstract: A method of calculating a transmitter and dispersion penalty for predicting optical link signal quality, includes provide an optical link; capture an averaged eye, using an optical test signal sequence to drive the transmitter with the oscilloscope receiver having an oscilloscope bandwidth as available; and from the averaged eye, capturing histograms A1; capture a non-averaged eye using an optical test signal sequence to drive the transmitter, and from the non-averaged eye, capturing histograms B1; de-convolve histograms A1 from histograms B1; filter waveform from 1) convolve the filtered waveform from 4) with the estimate of the noise from 3); calculate “soft” TDP based on said probability distribution function.

Abstract: A digital signal phase detector comprising a first circuit arranged to provide a phase difference signal representative of both the clock period of a clock signal and the difference in phase between the clock and a data signal, and a second circuit arranged to provide a reference signal representative of the clock period of the clock signal. At least one of the first and second circuits is coupled to a set point control signal and the corresponding output signal is representative of that set point control signal. A comparison of the phase difference signal with the reference signal provides an indication of the difference between the desired set point of the circuit and the phase difference between the clock and the data signal. A corresponding method of digital signal phase detection is also provided.

Abstract: The invention seeks to provide an improved, bandwidth-efficient method and apparatus for acquiring and tracking bursts of data, or continuous data, of varying and unpredictable amplitude, extinction ratio, and phase.The system avoids the use of digital signal processing which is not practical at high data signal rates. The system also obviates encoding of the data signal using a line code, thereby extending the existing technology to give a significant increase in data throughput for the same available bandwidth.The system may treat acquisition of each data burst, comprising alternate synchronisation parts and data parts, ab initio.

Abstract: An electrical switch (116) is disclosed having multiple inputs (214) and binary switches (312) operable to switch a signal from an input (214) via respective amplifiers (310). Amplifiers (310) are continuously operable and are provided with an auxiliary switching circuit (412) which provides the amplifier with a fixed voltage input signal when the associated input (214) is not selected. Response time upon selection of an amplifier (310) and crosstalk from any non-selected amplifier is minimised.

Abstract: The invention seeks to provide an improved method and apparatus for detecting thresholding errors in a digital signal recovered from a transmitted signal, wherein a derived threshold error signal varies linearly with the threshold error. Extraction of a threshold error signal linearly related to the actual threshold error enables increased speed of reaction of a threshold control circuit.