TDR measurement capability added to cable analyser

4th February 2015

Keysight Technologies (formerly Agilent)

Mick Elliott

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Datasheet

Keysight Technologies has two cable test options for its FieldFox handheld analysers. Cables (e.g., waveguide, coaxial and twisted-pair) are the most widely used components in RF and microwave communication systems. They are also the leading cause of their failure. During maintenance of these systems, engineers and technicians need to measure cable performance (e.g., return loss and voltage standing wave ratio (VSWR)), while also identifying fault locations and their cause (e.g., bad insulation, kinks and water ingress).

Such testing requires a cable and antenna analyser, network analyser, signal generator and power meter; all of which must be transported and set up for testing in the field. The process is error prone and leaves the instruments subject to accidental damage.

The new Time Domain Reflectometry (TDR) cable measurement option enables TDR measurements for the cable and antenna analyser. The option complements the analysers’ return loss (RL) and distance-to-fault (DTF) measurements.

Furthermore, it measures impedance changes along the cable and helps identify specific faults, while the analyser’s RL measurement capability exposes mismatch of cable connections and DTF capability indicates faults and poor connections along the cable.

Measuring long microwave cables in the field proves to be a very challenging task and requires instruments to provide a high dynamic range and fast and reliable results. The new FieldFox Extended Range Transmission Analysis option addresses one of the major challenges to measuring cables in the field; measuring in-situ, long lossy microwave cables. Accessing both ends of the cables or waveguides at the same time is difficult.

Using a signal generator with a broadband detector or power sensor to measure cable loss can be a slow process, it also is prone to external interference and does not allow high levels of dynamic range. Deploying a benchtop solution in the field to make the measurement is also non-ideal due to its large size and cost.

With Extended Range Transmission Analysis, two FieldFox instruments are deployed at each end of the measured cable. One analyser acts as a source, while the other acts as a receiver. Both instruments are step synchronised with hardware triggers. By taking advantage of Keysight’s proprietary InstAlign spectrum analysis technique, engineers and technicians can use this configuration to make very accurate cable loss measurements without calibration and warm up. This option can also be configured with frequency-offset to measure devices such as mixers and converters.

In additional to the new TDR cable test and extended range transmission analysis capabilities, FieldFox offers a number of features that make it ideally suited for cable test. It has the ability to measure RL, VSWR, impedance, insertion loss, and S-parameters with magnitude and phase. FieldFox can also be used for spectrum analysis or vector voltmeter measurements.