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RF test is a battle between PXI and benchtop

Frank Berthaux from Agilent Technologies discusses the pros and cons of opting for benchtop or PXI-based modular instruments for testing RF systems

 Agilent PXI

There is a debate taking place in the test and measurement industry about which is the best instrument form factor for RF test. Typically, this question centres on three form factors: benchtop, PXI-based modular and handheld.

The first important parameter to take into account is the type of product that will be developed and need to be tested.

For example, in manufacturing, military radar equipment will require completely different test systems than consumer products like tablets and handsets.

The quantity of units that need to be produced will influence the choice of test equipment, but so will the performance requirements the product is required to meet and the confidence the engineer wants to have in the measurement.

It is probably not dramatic if a mobile phone is shipped without testing every aspect of its performance at each step of the manufacturing process, as it can always be replaced or repaired later.

For something like a satellite payload; however, which costs several million dollars and cannot be repaired in orbit, the highest quality of measurement will be required, even in manufacturing test.

In addition, the specifications regarding temperature, stability, repeatability, and accuracy will be much more demanding for the payload than for the mobile phone. There are many variations in performance and test requirements between these two extremes, which make each situation different.

As shown in the previous example, we cannot generally decide that modular is always the best solution for manufacturing. The same is true for the benchtop form factor. It is not always the best solution for R&D.

Debug and analysis capabilities are generally the main drivers to choosing a solution in R&D; however, special types of products require different tests.

For example, Multiple Input Multiple Output (MIMO) transceivers need to be tested with multiple channel solutions. The test system should therefore, be able to generate and analys several signals in parallel.

In this case, a modular solution could be the right choice in R&D.

Even more complex is the situation where multi-channel requirements are important, but also where performance is critical.

In several applications, like radar testing, the best solution is often a mix of modular and benchtop solutions. For example, the baseband section could be tested using modular and the microwave section could be tested using benchtop instruments.

Finally, it is important to emphasise that test needs evolve over time. Manufacturing of mature products may require fewer tests than manufacturing brand new products. It may be necessary to change and adapt the test strategy throughout the product lifecycle. The same is true in early R&D, where it is often necessary to look for the most powerful test solutions with the best performance to debug first prototypes. Here, benchtop solutions provide interactive, flexible test tools for the most in-depth analysis and test. Later, in the same R&D department, as the focus shifts to characterisation and validation, the number of tests will increase and speed will become more important.

There is something else to consider when optimising time and resources related to tests along the product lifecycle. Choosing different form factors brings advantages, but it can also bring disadvantages.

How will, for example, the R&D, validation and manufacturing teams work together if their test strategy is based on different platforms and form factors, with different levels of accuracy and measurement intellectual property (IP)?

Many measurement and test results are based on the processing of samples to give meaningful information to the test engineer. If the samples and the measurement IP used to process this data are not consistent throughout the product lifecycle, it may create inefficiencies.

The measurements may be inconsistent and not repeatable, with little opportunity to make use of test cases and systems across different stages of the product lifecycle, Moreover, communication between the various departments involved with test will be more difficult.

There is an approach to this problem and it can remove those negative effects. The availability of two form factors could create synergies if they share the same measurement science: same measurement IP, same algorithms, same measurement software, same programming commands, and the same user interface.

Frank Berthaux, RF and microwave marketing manager, Agilent Technologies


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