Developing Dynamic Frequency Selection (DFS) Certification Tests
Using PXI
By Dana Redington
Redwolf Technology LLC
Submitted by NI
"The speed of generation and measurement of RF signals using PXI 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 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.
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 NI 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.
PXI tools used in this system ensured modularity and flexibility such that customers did not have to
purchase additional, unneeded hardware for the system requirements. NI 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 NI 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 PXI
Using PXI RF modular instruments and NI 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 RF modular instruments increased testing
throughput at a very cost-effective price point compared to alternative solutions. The flexibility of NI
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.
Author Information:
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.
Our DFS testing and reporting solution, based on NI LabVIEW and RF modular instruments, is designed
to aid in testing wireless products for the various international radar band requirements.
Our DFS solution is an integrated cost-effective and low-component solution with integrated test and data
capture for reporting.