RF test vendors prepare for billions of IoT devices

Billons of Internet of Things devices are presenting significant test-and-measurement challenges. Instrumentation makers are expanding their portfolios to meet the multi-standard testing requirements of devices that might connect via Bluetooth, Wi-Fi, ZigBee, cellular, or other wireless communications links, as described by a special report in our May issue.

As quoted in that article, David Hall, principal product manager for RF test systems at National Instruments, said, “It is widely understood that the IoT is literally introducing billions of wireless devices that use technologies ranging from Bluetooth to Wi-Fi to LTE, and of course ZigBee. Given the rising number and complexity of today’s wireless standards, IoT devices must support an increasing number of wireless interfaces in order to be commercially viable.”

Hall said that the flexibility and modularity of NI’s products enables customers to test a range of devices using a single platform. “For example,” he said, “customers use PXI to test everything from discreet power amplifiers (PA) to mobile devices to even the very sensor that enables the IoT device in the first place. Although many of these devices can require various instruments and test techniques, our customers can test any of these devices using a common hardware and software instrumentation platform.”

NI offers several specific products suitable for testing IoT technologies, including the Semiconductor Test System (STS) and Wireless Test System (WTS), as described in the May special report. “It is important to note that although NI’s manufacturing test solutions such as STS and WTS offer unique software and physical ruggedness, each of these solutions harnesses PXI instruments at their core,” Hall said. “Thus, our customers can use the same PXI instruments in manufacturing that they can use in R&D. Not only does this allow us to provide customers with R&D-grade instruments in manufacturing, but it also allows our customers more easily correlate measurement data from the R&D lab to data gathered on the manufacturing floor.”

Hall concluded, “One of the unique attributes of NI’s Vector Signal Transceiver (VST)—which is often used for wireless transceiver testing—is its user programmable FPGA. Customers are able to use the FPGA to more tightly synchronize signal generation and RF measurements with digital DUT control. As a result, many of our customers experience dramatic test time reductions.” In fact, he said, Qualcomm Atheros improved its test speeds by a factor of more than 200 by using the FPGA.

According to Dorine Gurney, Tektronix’s source and analyzer product planner, the company has “…been at the forefront of innovation and of understanding the new challenges designers face as IoT products incorporate various analog signals, high-speed and low-speed serial digital communication, microprocessor buses, and now RF circuitry.”

She cited some specific products. Tektronix mixed-domain oscilloscopes in the MDO3000 and MDO4000B Series add a dedicated RF input to the mixed-signal oscilloscope platform and provide a built-in spectrum analyzer combined with the basic functionality of a 16-channel logic analyzer. “In addition,” she said, “the MDO4000B can represent a timing relationship among its inputs—that is, the analog, digital, and RF signals. This feature can help locate the source of transient EMI, analyze the impact of a power supply voltage dip on an RF signal, or measure the time between symbols in a wireless bit stream, for example.”

RSA306 spectrum analyzer (Courtesy of Tektronix)

She added that Tektronix products are typically used in the forefront of the design, debug, and development process of IoT products, including characterization and qualification. “Because of the versatility, portability and attractive cost of the RSA306,” she said, referring to the company’s modular spectrum analyzer, “they are now also being used by software developers, validation engineers, and application engineers.”

Craig Hendricks, senior wireless business development manager at Anritsu, said “Anritsu provides test solutions for all stages of IoT. Our portfolio includes instruments that can test devices, final products, and infrastructure systems.” He added, “Anritsu has products for all stages of development, validation, characterization, debug, certification, and production.”

He elaborated on some instruments, including MS2830A spectrum/signal analyzer, which can be used as a spectrum analyzer, a signal generator, or a vector signal analyzer for RF testing of all major wireless standards, including cellular, Bluetooth, and Wi-Fi. The MS2830A, he explained has a unique one-button capture and playback feature that can be useful for testing IoT devices—it enables the user to transfer data acquired by the signal analyzer to the integrated signal generator, where it can be reproduced.

“For IoT designs utilizing Bluetooth,” he continued, Anritsu offers the MT8852B Bluetooth Test Set that can test Bluetooth in both network mode (with signaling) and in direct mode (non-signaling). It supports the Data Length Extension associated with Bluetooth Low Energy (BLE) as part of Bluetooth Core Specification version 4.2 and meets the extension of the data packet length in BLE from 37 octets to 255 octets. With the Data Length Extension option, designers and manufacturers can verify their Bluetooth Smart and Bluetooth Smart Ready devices for IoT applications.”

He then described the MT8860C WLAN test set, an integrated one-box instrument that can test 802.11a/b/g WiFi RF TX and RX in signaling mode without the need for chipset specific control as well non-signaling testing of 802.11a/b/g/n. “It provides a high-speed measurement solution that is suitable for both production testing and design proving,” he said.

Other instruments for IoT design and production test, he said, include the MT8820C radio communication analyzer for RF testing of cellular functions in signaling mode or non-signaling mode; it can test two devices fully independently simultaneously. In addition, Anritsu offers MG3710A vector signal generator for receiver and/or interference testing and the MS24106A USB power sensor, a tool for measuring RF power from 50 MHz to 6 GHz over a range of -40 dBm to +23 dBm.

“Anritsu also offers handheld, battery operated analyzers, such as the Spectrum Master MS2720T and MS2711E handheld spectrum analyzers and VNA Master MS202xC/3xC handheld vector network analyzers,” he said. “These instruments can be used for evaluating signals, finding interference and testing cables and antennas in RF devices and systems.”

Keysight also offers a broad range of solutions focused on components, chipsets, and complete products. Jan Whitacre, mainstream wireless technology lead at the company, said, “Keysight provides a broad range of RF and mmWave design and test solutions: network analysis, signal generation, signal analysis, one-box manufacturing testers, arbitrary waveform generation, EMI testing, interference testing, conformance test systems, and handhelds for deployment and maintenance.”

The development of IoT devices, she said, “…will follow the same steps as any wireless device with evaluation of the following characteristics: coverage range or sensitivity, power, radio spectrum/frequency, modulation quality, and interoperability.”

In addition, she said, “Battery drain is a major issue for IoT. There is high need to maximize battery life, minimizing the replacement of batteries in the field or on a person, as in a medical device. The other issue is dealing with long periods of standby operation between bursts of intense RF activity.”

She added, “Another area of unique capability for Keysight is in mmWave test.” The industry is looking to mmWave for IoT to get the needed spectrum and bandwidth, she said, noting that 802.11ad technology is being utilized fast in-room streaming. Further, 5G exploration is occurring at mWave frequencies. “Keysight has many years of experience in mmWave from its work in 802.11ad and aerospace/defense applications,” she concluded.

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