EDNE October 2012 - (Page 57)

need to choose between measurements of interest. With software designed instruments, functionality such as real-time spectral masking can be achieved at a fraction of the cost as with traditional “boxed” instruments. In addition, the low latency associated with performing measurements in hardware means that in the same time a standard test system may have required to take a single measurement, tens or hundreds of live measurements can be taken and averaged together. This means improved quality of test results and increased confidence in RF measurements. The concept can also be used to reach optimal test conditions quickly with closed-loop feedback. Certain classes of RF test require that DUT settings or environmental quantities are varied according to the measurements received; this requires a closed-loop system that is often limited by the latency of the software stack. In many cases, the loop can be closed directly in hardware, eliminating the need for subsequent setpoints to be computed using the CPU. This can reduce closed-loop test times from minutes to seconds. CusTom-DEFiNED TriGGErs sHarpEN FoCus Options for low-latency trigger behaviour are traditionally fixed according to the instrumentation hardware being used. However, with software-designed instrumentation, you can incorporate custom triggering functionality into your device to quickly zero-in on situations of interest. Flexible hardware-based triggering means that you can implement custom spectral masks or other complex conditions as criteria for either capturing important measurement data or activating additional instrumentation equipment. You may also reduce CPU processing loads with digital data reduction; processing large amounts of RF data can be taxing for even the most capable commercial CPUs, resulting in systems that have multiple controllers or that produce extended test times. With software-designed instrumentation, you can preprocess data in hardware, potentially reducing the CPU load significantly. Computations such as fast Fourier transforms (FFTs), filtering and modulation/demodulation can be implemented in hardware, reducing the amount of data that must be passed to and processed by the CPU. There is no doubt that vendor-defined instruments will remain available for years to come, since they are well suited to interactive, bench-top measurements. However, just as increasingly complex RF devices and pressure on time to market has lead to the rise of software-based instrumentation systems, the continuation of these trends means that softwaredesigned instruments will play an increasingly important role in test in the near future. RF is just one area that can benefit from the flexibility and performance of FPGA-based hardware, and it is only a matter of time before more instruments follow its lead in redefining the way test and measurement is performed.EDN Author’s biogrAphy Jeremy Twaits is Regional Marketing Engineer – Automated Test, for National Instruments’ UK & Ireland operation. www.edn-europe.com OCTOBER 2012 | EDN EuropE 57 http://www.digikey.com/europe http://www.edn-europe.com

Table of Contents for the Digital Edition of EDNE October 2012

Cover
Contents
International Rectifier
Microchip
RS Components
Masthead
Microchip
EDN Comment
Pulse
Analog Devices
Farnell
Baker's best
Omicron
Test & Measurement World
Agilent Technologies
Maxim Integrated Products
Maxim Integrated Products
Digi-Key
Mixed-signal SOC verification using analog behavioral models
Messe München
Bergquist
The future of connected-device security
Silicon Laboratories
Digi-Key
Coilcraft
Messe München
Image sensors evolve to meet emerging embedded vision needs
Digi-Key
Chip Expo
National Instruments
Supply chain
Introducing software-designed instrumentation to test-and-measurement
Digi-Key
Mechatronics in design
Design ideas
Product Roundup
Tales from the cube

EDNE October 2012