Noise suppression techniques in high precision long-term frequency/timing measurements

A method to reduce correlated noise comprising the steps of:

• providing a reference source that generates a reference source signal and at least one target source that generates a target source signal, said reference source and said target source configured to establish a correlation of phase noise between said reference source signal and said at least one target source signal;
• providing a measurement block configured to measure a selected one of said reference source signal and said target source signal;
• counting N times differentially at least one of said at least one target source signal and said reference signal to provide N differential measurements;
• computing a reduced correlated noise measurement of each of said at least one target sources based on an average of said N differential measurements;
• and
• recording each of said reduced correlated noise measurements.

A frequency/timing measurement apparatus comprising:

• a reference source having a reference source terminal;
• at least one target source having a target source terminal;
• at least one active core having at least two active core inputs, and an active core output terminal, said active core configured to generate a frequency representative of a selected one of an inductance of said at least one target source and an inductance of said reference source;
• a switching circuit configured to electrically couple to said active core in a selected one of a time multiplexed manner and a simultaneous manner to a selected one of said reference source terminal and said at least one target source terminal;
• and
• a frequency timing measurement block having a frequency timing measurement block input terminal electrically coupled to said active core output terminal, and at least one frequency timing measurement block output terminal, said frequency timing measurement block configured to perform a noise shaping technique to reduce measurement error attributable to a phase noise that is correlated between said reference source and said target source, and to provide a reduced correlated noise measurement at said at least one frequency timing measurement block output terminal.