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As wireless technology continues to evolve, more wireless IC solutions are becoming available in the marketplace, making them nearly ubiquitous. Once a particular wireless technology is selected, wireless radio module OEMs face the challenging task of incorporating the radio IC into their application. Selection of the right wireless IC can reduce engineering demands and accelerate the time-to-market of the radio module. Beyond the technical specifications of competing IC solutions, the availability of the right development platform plays a big role in this selection process.
Every manufacturer of wireless electronic equipment must meet regulatory standards where the equipment will be sold or used. Radio compliance is one of the major hurdles for wireless OEMs and the sooner this is addressed in the design cycle, the faster the OEM can move towards product launch. Typically an OEM designs a module around a wireless IC and once the design nears completion, it has to develop test firmware and hardware to test the radio module. This approach adds to the total development time and cost and can yield catastrophic results. Thinking about radio compliance at the very end of the development cycle also increases the ROI risk considering the possibility of an unforeseen regulatory spec failure. Hence systematic designing for compliance is vital to reducing retesting costs required by non-compliance; in effect accelerating revenue realization from new products1.
Having an RF development platform available during the design and development phase with the necessary firmware to test radio transceiver parameters speeds up prototype development stages in a sequential and progressive manner. Modifications can be made in the design during prototyping stages itself to accommodate for performance issues if any. This approach also offloads the OEM's responsibility to develop the test platform for the specific radio module. Such an RF development platform which also covers the regulatory precertification tests before going to final compliance testing drops the OEM's ROI risk considerably.
RF development platform essentials
From the OEM's perspective the RF development platform should accomplish majority of the basic transceiver tests and double up as a pre-compliance test platform for specific regulatory tests. It should have a simple serial port interface to any readily available terminal program such as HyperTerminal or ProComm. This obviates the need to for purchasing expensive software and cuts down on the software learning curve considerably. The idea is to have part of the firmware running on the test platform and the other half running on the CPU which interfaces with the radio. In this manner multiple RF tests can be carried out in a single hardware set-up by issuing commands from the RF test platform to the OEM radio module over the wireless link itself.
RF Test platform in action
During the design cycle such an RF development platform provides a means of testing range with a limit-of operating condition. Packet data can be sent by the test kit to the DUT over the wireless link. The firmware running on the DUT simply echoes the data back to the test kit. ased on the data received, the RF test platform calculates the PER (packet error rate) for the transmit-receive sequence. Since the range for a wireless device doubles with every 6 dB of reduced path loss, a step attenuator can be connected in series with the test set and range testing can thus be simulated. This provides a very simple and reliable method for carrying out comparative evaluation of various prototype stages.
Additionally by varying the orientation of the DUT inside an anechoic chamber and conducting receiver tests, the radiation pattern performance of the designed antenna can be safely predicted. This provides a cheap and quick alternative to measuring antenna characteristics during prototype design stages.
Figure 1. Test set-up for range measurements
Pre-certification compliance testing
One of the bottlenecks that many product developers encounter in incorporating any radio communication IC is facing the legal aspect of qualifying the products and going to market without encountering legal problems. Manufacture and sale of wireless products intended for unlicensed operation in the 2.4GHz ISM band are governed in the United States under CFR 47 Part 15 and Industry Canada. These products must at the very least pass the following tests: spurious radiation emissions, spurious conducted emissions, power line conducted emissions, output power, occupied bandwidth, band edge compliance and power spectral density.
The RF development platform can issue commands to put the DUT in unmodulated or modulated carrier modes. This facilitates the measurement of maximum transmit power as well as the occupied bandwidth as shown in Figure 2.
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