Daniel F Harkins

US Patent:

53329740, Jul 26, 1994

Filed:

May 1, 1990

Appl. No.:

7/518042

Inventors:

Daniel R. Harkins - Santa Rosa CA
Paul R. Hernday - Santa Rosa CA
Roger W. Wong - Santa Rosa CA
William T. Pike - Santa Rosa CA
Paul S. Stafford - Santa Rosa CA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

G01R 3500

US Classification:

324606

Abstract:

A method to verify that a test and measurement system continues to operate within a predetermined acceptable range with respect to a given calibrated state previously defined for that system without the need for conventional external reference components. In accordance with one embodiment, performance verification of a network analyzer used to perform electrical measurements is achieved by storing RF "thru" measurement data (an RF thru measurement trace of the system) at the time of calibration at the factory or later repair and/or recalibration at a field service site. In accordance with another embodiment, performance verification of a lightwave component analyzer, used to perform electrical, electro-optical, opto-electrical, and optical measurements, is achieved by storing RF and optical thru measurement data (both an RF thru measurement trace of the system and an optical thru measurement trace of the system) at the time of calibration at the factory or later repair and/or recalibration. In both cases, at the time of manufacture, the key measurement paths (with calibrated reference components in the loop) of the test and measurement system are measured and stored in system memory or, alternatively, on a disc that is shipped with the system. Repeating these measurements with the same thru connection(s) at a later time(s) indicates how well the test and measurement system is reproducing the conditions of its initial calibration.