Developing Dynamic Frequency Selection (DFS) Certification Tests Using LabVIEW and NI RF Modular Instruments

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"The speed of generation and measurement of RF signals using NI RF modular instruments increased testing throughput at a very cost-effective price point when compared to alternative solutions."

- Dana Redington, Redwolf Technology LLC

The Challenge:
Replacing expensive, piecemeal, manual solutions for DFS testing with an integrated and automated lower-cost alternative.

The Solution:
Using NI PXI modular instruments and NI LabVIEW software to develop a fully integrated hardware and software solution for DFS testing that provides generation of DFS patterns, analyzes the response of the unit under test (UUT), and generates a sophisticated set of reports with all necessary data to ensure compliance.

Author(s):
Dana Redington - Redwolf Technology LLC

Redwolf is a Silicon Valley business specializing in prototyping smart, next-generation technology, and intelligent products. Since the late 1980s, previous projects have included next-generation consumer products, medical instruments and instrumentation, and automated methods for test and measurement in emissions testing, industrial lasers, and silicon wafer processing.

The Need for DFS Testing

The current trend of increasing use of wireless systems has introduced the potential conflict with licensed radar bands. DFS is the process of detecting radar signals that must be protected against Wi-Fi interference (802.11a, 802.11b, 802.11g, and 802.11n), and upon detection switching the Wi-Fi operating frequency to one that does not interfere with the radar systems. Transmit power control (TPC) is used to adapt the transmission power based on regulatory requirements and range information. 

The need to implement this process in all of today’s wireless devices has introduced additional compliance requirements. For example, a test report can include hundreds of pages with a large data set in tables and screen captures. In addition, the variation of implementing this process based on the geographical location has added an extra level of complexity required to properly test these devices. Global certification laboratories as well as global OEMs are scrambling to implement all testing to ensure compliance in different countries around the world. For example, in the United States, the DFS requirements are detailed in FCC Part 15 Subpart. In Europe, the ETSI EN 302 502 guidelines are followed. And in Japan, the Japanese Radio Law 5 GHz includes DFS-related guidelines. 

Different customers have different challenges implementing a DFS test solution. For example, certification labs are faced with having to quickly design a DFS test system using separate lab instruments such as vector signal generators (VSGs) with no automation software to keep track of all the different radar patterns needed to properly test any kind of wireless device that comes through the labs. OEMs, on the other hand, are faced with the challenge to design a similar system that can be used in house to perform precertification tests and avoid costly failure runs at the official certification labs. Several large global OEMs also have their own internal authorized certification labs that face the same challenge as the third-party independent labs. In addition, customers also need a fast and efficient way to automate the generation of all the proper reports to ensure compliance with the different global guidelines. 

Redwolf Solution

Our DFS testing and reporting application is designed to aid in testing of wireless products for the various international radar band requirements. We designed and implemented the DFS system to perform compliance testing according to the following standards:

-       FCC (06-96) 5.25 to 5.35 GHz and 5.47 to 5.725 GHz guidelines

-       ETSI EN 302 502 (2006-11) guidelines

-       Japanese Radio Law 5 GHz (802.11a)

The system hardware consists of an NI PXI chassis with an embedded controller, an NI PXIe-5673 RF VSG with an upconverter, and the NI PXIe-5663 RF vector signal analyzer (VSA). We wrote the custom DFS testing software in LabVIEW. The DFS solution from Redwolf is an integrated cost-effective and low-component solution. It has integrated test and data capture for reporting and is designed to minimize test time and increase test throughput.

Before this system existed, certification labs and OEMs were forced to build a custom system using existing lab equipment. Customers performed the tests by manually generating each radar pattern, monitor, and record responses from the UUT. This was a very time-consuming process, which did not even include the time required to develop extensive reports with massive amounts of data collected to ensure compliance. 

NI tools used in this system ensured modularity and flexibility such that customers did not have to purchase additional, unneeded hardware for the system requirements. LabVIEW was a perfect tool for automating the creation and generation of the different types of radar patterns required to test. The report generation tools available in LabVIEW are heavily used to automate the reporting of test results and create professional reports that adhere to the guidelines set by the different regulatory groups around the world.   

Advantage of Working with NI

Using NI PXI RF modular instruments and LabVIEW, we developed a DFS system that delivers higher testing efficiency, lower total test time, and superior reporting quality. The system is an integrated solution, which is smaller than other custom-built alternatives. The PXI platform enabled the implementation of test and data capture in a single-chassis solution. Also, the speed of generation and measurement of RF signals using NI RF modular instruments increased testing throughput at a very cost-effective price point compared to alternative solutions. The flexibility of LabVIEW programming will enable future improvements for precertification DFS testing, such as developing custom-scripted tests with smart interaction with UUTs and further automation of the report generation. The NI team including Ahmed Mahmoud and Conan McHugh from the Northern California sales team and Heath Noxon from the NI RF segment has been very supportive throughout the development of this integrated solution.

Author Information:
Dana Redington
Redwolf Technology LLC
Tel: 650-302-0505
dana@redwolf.com

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