US 5,332,974 A · Network analyzer performance verification

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. Setting a range of allowable deviation (for measurement repeatability and normal system drift) between the initial and any later measurements establishes limits within which the integrity of the test and measurement system hardware performance is assured for subsequent measurements on an unknown device under test.

Claims18

Dependent claims

A verification method for monitoring hardware performance of a network analyzer system, used to perform electrical measurements, to detect deviations, or changes, over time as compared to the system status at the time of factory or other reference calibration, comprising the steps of:

providing an initial calibration for the system during a first time period;
connecting an RF cable between an RF signal output port and an RF signal input port during the first time period after the initial calibration of the system;
performing a measurement on the RF cable and an associated measurement path in the system during the first time period to produce first RF thru measurement data comprising an RF thru measurement trace of the system measured using the RF cable during the first time period;
storing the first RF thru measurement data;
disconnecting the RF cable;
reconnecting the RF cable between the RF signal output port and the RF signal input port during a second time period after the first time period;
repeating a measurement on the RF cable and the associated measurement path in the system during the second time period to produce second RF thru measurement data comprising an RF thru measurement trace of the system measured using the RF cable during the second time period;
and
comparing the first and second RF thru measurement data, without modifying the initial calibration for the system, to determine differences therebetween to indicate whether the system is reproducing the RF thru measurement conditions determined during the first time period when it is initially calibrated.

6 more elements

A verification method for monitoring hardware performance of a lightwave component analyzer system, used to perform electrical, electro-optical, opto-electrical, and optical measurements, to detect deviations, or changes, over time as compared to the system status at the time of factory or other reference calibration, comprising the steps of:

providing an initial calibration for the system during a first time period;
connecting an RF cable between an RF signal output port and an RF signal input port during the first time period after the initial calibration of the system;
connecting an optical cable between an optical signal output port and an optical signal input port during the first time period after the initial calibration of the system;
performing a measurement on the RF cable and an associated measurement path in the system during the first time period to produce first RF thru measurement data comprising an RF thru measurement trace of the system measured using the RF cable during the first time period;
performing a measurement on the optical cable and an associated measurement path in the system during the first time period to produce first optical thru measurement data comprising an optical thru measurement trace of the system measured using the optical cable during the first time period;
storing the first RF thru measurement data and first optical thru measurement data;
disconnecting the RF cable;
disconnecting the optical cable;
reconnecting the RF cable between the RF signal output port and the RF signal input port during a second time period after the first time period;
reconnecting the optical cable between the optical signal output port and the optical signal input port during a second time period after the first time period;
repeating a measurement on the RF cable and the associated measurement path in the system during the second time period to produce second RF thru measurement data comprising an RF thru measurement trace of the system measured using the RF cable during the second time period;
repeating a measurement on the optical cable and the associated measurement path in the system during the second time period to produce second optical thru measurement data comprising an optical thru measurement trace of the system measured using the optical cable during the second time period;
and
comparing the first and second RF thru measurement data and the first and second optical thru measurement data, without modifying the initial calibration of the system, to determine differences therebetween to indicate whether the system is reproducing the RF thru measurement conditions and optical thru measurement conditions determined during the first time period when it is initially calibrated.

11 more elements

A verification method for monitoring hardware performance of a test and measurement system, used to perform at least one of electrical, electro-optical, opto-electrical, and optical measurements, to detect deviations, or changes, over time as compared to the system status at the time of factory or other reference calibration, comprising the steps of:

providing an initial calibration for the system during a first time period;
connecting at least one of an RF connecting means between an RF signal output port and an RF signal input port and an optical connecting means between an optical signal output port and an optical signal input port during the first time period after the initial calibration of the system;
performing a measurement on at least one of the RF connecting means and an associated measurement path, to produce first RF thru measurement data comprising an RF thru measurement trace of the system measured using the RF connecting means, and a measurement on the optical connecting means and an associated measurement path, to produce first optical thru measurement data comprising an optical thru measurement trace of the system measured using the optical connecting means, during the first time period;
storing at least one of the first RF thru measurement data and first optical thru measurement data;
disconnecting any previously connected connecting means;
reconnecting the at least one RF connecting means between the RF signal output port and the RF signal input port and the optical connecting means between the optical signal output port and the optical signal input port during a second time period after the first time period;
repeating a measurement on the at least one of the RF connecting means and the associated measurement path in the system, to produce second RF thru measurement data comprising an RF thru measurement trace of the system measured using the RF connecting means, and the optical connecting means and the associated measurement path in the system, to produce second optical thru measurement data comprising an optical thru measurement trace of the system measured using the optical connecting means, during the second time period;
and
comparing at least one of the first and second RF thru measurement data and the first and second optical thru measurement data, without modifying the initial calibration for the system, to determine differences therebetween to indicate whether the system is reproducing at least one of the RF thru measurement conditions and the optical thru measurement conditions determined during the first time period when it is initially calibrated.

6 more elements

Dependencies are inferred from the claim text.

Network analyzer performance verification

Life of this patent

Network analyzer performance verification

Life of this patent

Abstract

Claims18