Noise margin measurement of a repeating signal under test (SUT)

A test system implemented method of measuring the noise margin of a repeating signal under test (SUT), comprising:

• determining a digitizer noise of a digitizer channel of the test system;
• applying the repeating SUT to the digitizer channel of the test system;
• acquiring multiple real-time waveform representations of the repeating SUT, wherein the waveform representations are oversampled such that a Nyquist frequency of the waveform representation is greater than deterministic maximum frequency of the repeating SUT;
• averaging the multiple real-time waveform representations to obtain a new waveform;
• creating multiple noise sequences by subtracting the new waveform from each of the multiple real-time waveforms;
• and
• determining a noise margin om of the repeating SUT in accordance with the following equation,
• σ
• m
• =
• (
• σ
• c
• 2
• +
• σ
• i
• 2
• -
• σ
• d
• 2
• )
• 1
• /
• 2
• where σc, is a standard deviation of a maximum amount of gaussian noise that can added to the new waveform representation without its symbol error rate (SER) exceeding a target value;
• where σi is a standard deviation of the digitizer noise, and
• where σd is a standard deviation of the multiple noise sequences.

A non-transitory tangible computer readable medium having stored thereon executable instructions embodied in the computer readable medium that when executed by at least one processor of a test system cause the test system to execute a method of measuring the noise margin of a repeating signal under test (SUT), the method including:

• acquiring an equivalent-time waveform representation of the repeating SUT, wherein the waveform representation is oversampled such that a Nyquist frequency of the waveform representation is greater than deterministic maximum frequency of the repeating SUT;
• obtaining a filtered waveform representation in which noise components of the equivalent-time waveform representation outside of the deterministic maximum frequency are removed, and
• determining a noise margin σm of the repeating SUT in accordance with the following equation,
• σ
• m
• =
• (
• σ
• c
• 2
• +
• σ
• i
• 2
• -
• σ
• d
• 2
• )
• 1
• /
• 2
• where σc, is a standard deviation of a maximum amount of gaussian noise that can added to the filtered waveform representation without its symbol error rate (SER) exceeding a target value;
• where σi is a standard deviation of a digitizer noise of the test system, and
• where σd is a standard deviation of the noise components removed to obtain the filter waveform representation.