Measuring error in signal under test (SUT) using multiple channel measurement device

A system for measuring a characteristic of a signal under test (SUT) output by a device under test (DUT), the system comprising:

• a first analog to digital converter (ADC) configured to receive a first copy of the SUT via a first input channel, and to digitize the first copy of the SUT to obtain first digitized waveforms;
• a second ADC configured to receive a second copy of the SUT via a second input channel, and to digitize the second copy of the SUT to obtain second digitized waveforms;
• at least one processor;
• and
• at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the at least one processor to:
• repeatedly determine a first measurement trend to obtain a plurality of first measurement trends, each first measurement trend corresponding to measurements of the SUT characteristic in the first digitized waveforms, respectively;
• repeatedly determine a second measurement trend to obtain a plurality of second measurement trends, each second measurement trend corresponding to measurements of the SUT characteristic in the second digitized waveforms, respectively, each second measurement trend being paired with a first measurement trend, respectively, to obtain a plurality of measurement trend pairs;
• cross-correlate the first measurement trend and the second measurement trend in each of the measurement trend pairs to obtain a plurality of cross-correlation vectors;
• extract a plurality of zero-displacement values from the plurality of cross-correlation vectors, respectively;
• sum the plurality of zero-displacement values of the plurality of cross-correlation vectors to obtain a sum of measurement products for the plurality measurement trend pairs;
• divide the sum of zero-displacement values by a total number of measurement products of the plurality of cross-correlation vectors to obtain an average value of the measurement products, which corresponds to a mean-squared value (MSV) of the measured SUT characteristic;
• and
• determine a square root of the average value of the MSV to obtain a root-mean-squared (RMS) value of the measured SUT characteristic,
• wherein the RMS value includes variations in the SUT, which are in both the first and second input channels, and substantially omits un-correlated variations not in the SUT, which are introduced by only one of the first input channel or the second input channel.

A non-transitory computer readable medium storing instructions for measuring a characteristic of a signal under test (SUT) output by a device under test (DUT), that when executed by at least one processor, cause the at least one processor to:

• receive first digitized waveforms of a digitized first copy of the SUT from a first input channel;
• receive second digitized waveforms of a digitized second copy of the SUT from a second input channel;
• repeatedly determine a first measurement trend to obtain a plurality of first measurement trends, each first measurement trend corresponding to measurements of the SUT characteristic in the first digitized waveforms, respectively;
• repeatedly determine a second measurement trend to obtain a plurality of second measurement trends, each second measurement trend corresponding to measurements of the SUT characteristic in the second digitized waveforms, respectively, each second measurement trend being paired with a first measurement trend, respectively, to obtain a plurality of measurement trend pairs;
• cross-correlate the first measurement trend and the second measurement trend in each of the measurement trend pairs to obtain a plurality of cross-correlation vectors;
• extract a plurality of zero-displacement values from the plurality of cross-correlation vectors, respectively;
• sum the zero-displacement values of the plurality of cross-correlation vectors to obtain a sum of measurement products for the plurality measurement trend pairs;
• divide the sum of zero-displacement values by a total number of measurement products of the plurality of cross-correlation vectors to obtain an average value of the measurement products, which corresponds to a mean-squared value (MSV) of the measured SUT characteristic;
• and
• determine a square root of the average value of the MSV to obtain a root-mean-squared (RMS) value of the measured SUT characteristic,
• wherein the RMS value includes variations in the SUT, which are in both the first and second input channels, and substantially omits un-correlated variations not in the SUT, which are introduced by only one of the first input channel or the second input channel.