Method of calculating transmitter and dispersion penalty for predicting optical data link and signal quality
AssigneeMellanox Technologies Denmark Aps
InventorPiers James Geoffrey DAWE
Life of this patent
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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.
Claims26
A method of calculating a transmitter and dispersion penalty for predicting optical link signal quality, said method comprising:
- 0) provide an optical link comprising an optical transmitter, an optical fiber, and an optical oscilloscope receiver linked together;
- 1) 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;
- 2) capture a non-averaged eye using an optical test signal sequence to drive the transmitter, and from the non-averaged eye, capturing histograms B1;
- 3) de-convolve histograms A1 from histograms B1, giving an estimate of the noise on the signal and the noise stemming from the oscilloscope;
- 4) filter waveform from 1), i.e. the waveform that gave the averaged eye, as if in a bandwidth representative of the dispersion of the fiber link and the expected bandwidth of a data receiver in service,
- 5) convolve the filtered waveform from 4) with the estimate of the noise from 3);
- proving an eye and capturing the histogram of said eye providing a probability distribution function;
- 6) calculate “soft” TDP based on said probability distribution function.
A method of calculating transmitter and dispersion penalty for predicting optical link signal quality, said method comprising the following steps:
- 0. Provide a 100 Gb/s optical link comprising an optical transmitter, an optical fiber enabled for 100 Gb/s transmission, and an optical oscilloscope receiver;
- A. Capture an averaged eye and the waveform that gave the averaged eye using a test pattern, with the oscilloscope receiver having an oscilloscope bandwidth as available, such as 19 GHz;
- A1. Capture histograms from averaged eye;
- B. From non-averaged eye, e.g. using PRBS9 pattern, capture histograms;
- C. Deconvolve A1 from B, giving an estimate of the wideband noise;
- D. From non-averaged eye, e.g. using PRBS31 pattern, capture histograms;
- E. Deconvolve B from D, giving an estimate of the low frequency noise and patterning;
- F. Filter the waveform i.e. the waveform that gave the averaged eye A as if in a bandwidth representative of the dispersion of the fiber link and the expected bandwidth of a data receiver in service, e.g. 12.6 GHz for a 26 GBd signal in 100GBASE-SR4, e.g. using a processor;
- G. Convolve with about 80% of noise C and all of noise E;
- H. Calculate the TDP.
A method of calculating a transmitter and dispersion penalty for predicting optical link signal quality, said method comprising providing an optical link comprising an optical fiber, an optical transmitter and an optical oscilloscope receiver;
- TDP1—Measure scope noise S with no input;
- TDP2—Calculate the largest expected amount of Gaussian noise G, preferably comprising that of the optical oscilloscope receiver and optionally other noises, that could be tolerated for a predetermined target bit error ratio;
- TDP2A—Estimate largest expected modal noise M;
- TDP2B—Estimate largest expected mode partition noise N from worst case transmitter and channel spectral properties, using established formulas, such as in the 10 Gigabit Ethernet link model;
- TDP2C—Root sum square the noises from one or more of TDP2A and TDP2B and TDP2 and TDP1 giving the required maximum receiver noise R in order to reach target BER;
- TDP3—resulting in a TDP which is proportional to the result of TDP2C.
Dependencies are inferred from the claim text.