US 7,512,196 B2Granted

System and method of obtaining random jitter estimates from measured signal data

AssigneeGuideTech Inc.

InventorSassan Tabatabaei

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Abstract

A method of estimating random jitter from measured samples of a transmitted data signal includes a first step of obtaining a plurality of measurements (e.g., pulse widths) for selected signal edges within a transmitted data stream, where the data stream comprises a repeating data pattern having a known bit length and known number of rising edges, and wherein the time difference between adjacent measurements is determined by an event count increment equal to an integer multiple of the known number of rising edges. A time interval error (TIE) value is then computed for each measured signal edge and transformed into corresponding frequency components that are representative of both noise floor and multiple distinct frequency peaks. Noise floor is isolated and the power of the noise floor may be computed to provide an estimate of random jitter variance, from which the standard deviation may be calculated.

Claims27

Dependent claims

A method of estimating random jitter from measured samples of a transmitted data signal, said method comprising the following steps:

obtaining a plurality of measurements, using at least one measurement channels system, for a plurality of selected signal edges within a transmitted data stream, wherein the transmitted data stream comprises a repeating data pattern, wherein each iteration of the data pattern has a given number of multiple pulses, wherein each iteration of the data pattern does not correspond to uniform repetition of a single pulse, and wherein the time difference between adjacent measurements is determined by an event count increment equal to an integer multiple (M) of the given number of multiple pulses within the repeating data pattern;
computing a time interval error (TEI) value, using a processor circuit, for each measured signal edge in said obtaining step;
transforming TIE values, using the processor circuit, into corresponding TIE components for selected of the measured signal edges, wherein said TIE frequency components are representative of both noise floor as well as multiple distinct frequency peaks;
separating the noise floor from the multiple distinct frequency peaks, using the processor circuit;
computing the power of the noise floor within the TIE frequency components, using the processor circuit;
and
providing an output indicative of the computed power of the noise floor to obtain an estimate of the random jitter variance using the processor circuit.

4 more elements

A measurement system configured to obtain random jitter estimates for a transmitted signal, said measurement system comprising:

at least one measurement channel for obtaining multiple respective start and stop measurements for selected signal edges within the transmitted data signal, wherein the transmitted data signal comprises a repeating data pattern of multiple pulses having a known bit length and known number of multiple rising edges, wherein each iteration of the data pattern does not correspond to uniform repetition of a single pulse, and wherein the time difference between adjacent start measurements is determined by an event count increment equal to an integer multiple (M) of the known number of multiple rising edges within the repeating data pattern;
and
a processor circuit coupled to said at least one measurement channel, said processor circuit configured to determine the time interval error for each start and stop measurement, to transform selected of the time interval error values into corresponding TIE frequency components, to separate noise floor from multiple distinct frequency peaks in the TIE frequency components, and to compute the power of the noise floor within the TIE frequency components to obtain an estimate of random jitter variance.

Dependencies are inferred from the claim text.