The Boonton PMX40 RF Power Meter Offers the Ultimate Combination of Performance and Flexibility

August 25, 2020

For decades, RF power measurements were made with benchtop power meters, which historically utilized analog sensors connected via an analog cable. Featuring knobs, buttons, and a digital display, these durable instruments are still widely used by many engineers today. However, several years ago USB power meters were introduced which incorporated the majority of the benchtop’s functionality within the USB RF power sensor itself. These sensors ushered in a new methodology for RF power measurements, delivering a more compact and portable solution that erased the tried-and-tested knobs, buttons, and digital display with a graphical user interface displayed on a user-supplied computer. Control of the sensors is through either software supplied by the vendor or directly, with software developed by the user.

Figure 1: The PMX40 RF power meter with a series of USB RF power sensors

Although offering benefits in performance and portability, USB RF power meters left various concessions in their wake. Leading the charge in high-performance RF and microwave test equipment, Boonton sought to deliver the best of both worlds, removing the tradeoffs between traditional benchtop instruments and computer-connected USB RF power sensors. In comes the PMX40 RF power meter, which merges the utility of a traditional benchtop instrument, the flexibility and performance of USB RF power sensors, and the simplicity of a modern multi-touch display, all built with Boonton award-winning technology (see Figure 1).

The PMX40 RF Power Meter

The PMX40 retains the physical user interface of traditional benchtop meters, but with a modern, sleek design and streamlined functionality, as shown in Figure 2. Its multi-touch display with an intuitive user interface enables fast sensor configuration as well as speedy access to analysis tools that together deliver a standalone RF power measurement solution for capturing, displaying, and analyzing peak and average RF power in the time and statistical domains. The meter can utilize up to four sensors either independently or for synchronized multi-channel measurements of continuous wave (CW), modulated, and pulsed signals.

Figure 2: The front panel of the PMX40 RF power meter

Users can easily switch between three measurement modes while navigating the user interface. For starters, “Continuous Mode” displays a numerical value for a repetitive signal’s average, maximum, and minimum power measurements. Providing up to 16 automatic pulsed parameters, “Pulsed Mode” delivers the triggering and data acquisition capabilities needed to capture pulses with quick rise times or short pulse repetition intervals (PRIs). Lastly, the PMX40 enables statistical measurements of modulated signals that often have a noise-like appearance by plotting the Complementary Cumulative Distribution Function (CCDF) while in “Statistical Mode.” A CCDF curve is a statistical representation of how frequently a specific crest factor occurs for modulated signals, such as those used in 5G, 4G/LTE, and Wi-Fi applications.

The front panel also incorporates a test source to verify sensor operation, as well as the ability to sync ports to source or receiver triggers for optimal timing and synchronization. To further increase ease of use, users can access preset and favorite functions with the simple push of a front panel button.

The PMX40 benchtop power meter adorned with its simple, multi-touch display is not complete without the high performance and versatile RTP and CPS families of USB RF power sensors (see Figure 3). While the PMX40’s front panel display brings back the utility of benchtop instruments, the USB RF power sensors continue to deliver their flexibility and functionality to effectively eradicate RF power meter design compromises. Covering a frequency range from 4 kHz to 40 GHz, the PMX40 and associated sensors provide industry-leading performance, including the widest video bandwidth of 195 MHz, quickest 3-nanosecond (ns) rise time, fastest measurement rate at 100,000 measurements per second, and finest 100-picosecond (ps) time resolution.

Figure 3: The PMX40 with the RTP and CPS families of USB RF power sensors

Providing superior performance and automatic pulse measurements, Boonton RTP5000 series Real-Time Peak Power Sensors are the ideal solution for fast, accurate, and reliable RF and microwave peak power measurements. Providing the lowest frequency measurements with diode-based average power sensors, the RTP4000 series Real-Time True Average Power Sensors produce accurate measurements that are virtually independent of signal modulation bandwidths. The CPS2000 True Average Connected Power Sensors, on the other hand, provide USB and LAN with Power over Ethernet (PoE), capabilities to enable RF power measurement of modulated and CW signals ranging from 50 MHz to 8 GHz—all with a low price point.

Boonton’s range of sensors and new RF power meter are not eternally linked to one another, but rather share a relationship with flexibility at its core. As a result, the PMX40 sensors can be disconnected and used on their own to provide versatility as test and measurement needs change.  

The PMX40 along with its USB RF power sensors are able to deliver unmatched measurement speeds and performance through harnessing Boonton’s Real-Time Power Processing™ (RTPP) technology. All RTP Real-Time Power Sensors incorporate Boonton’s powerful RTPP technology, which virtually ensures no gaps in signal acquisition and zero measurement latency. Instead of waiting the full duration of the acquisition cycle, RTPP uses an optimized parallel processing methodology to perform the majority of sweep processing steps all at once at the start of a pre-defined trigger event. Therefore, RTPP eliminates computational overhead and guarantees gap-free signal acquisition, reliably capturing and analyzing important signal phenomena such as transients or dropouts (see Figure 4).

Figure 4: The PMX40 and USB RF power sensors can capture critical events, such as dropouts, which are often missed by conventional instruments

Additional software features include the ability to measure and calculate up to 16 common power and timing parameters, as well as statistical analysis tools for calculating crest factor and plotting CCDF for characterizing device-under-test (DUT) performance.

The Boonton RTP Series Measurement Buffer Mode Application channels the power of RTPP in a complementary software package. While using the RTP Series Measurement Buffer Mode Application, users can capture only relevant burst information, such as peak, average, and minimum power during each pulse period, as well as the start time and measurement duration. Therefore, extraneous information is discarded during non-relevant intervals, which reduces the amount of storage required for the acquired data points. As a result, measurements can be sustained for extremely long periods of time—making this an ideal device characterization and monitoring tool.  

PMX40 Applications: RF Communications, Radar, and More

The PMX40 streamlines RF testing and increases instrument versatility for broad use in the semiconductor, military, aerospace, medical, and communications industries. Although the RF power meter can add value for design engineers and technicians in numerous applications, the PMX40 is especially equipped to address RF communications and radar measurement challenges.  

Characterization and compliance testing of Wi-Fi chipsets and devices is complex considering multiple-input, multiple-output (MIMO) architectures and channel bandwidths up to 160 MHz, which often require compromises when measuring RF power per channel and time alignment between channels. The PMX40 and associated RTP5000 USB peak power sensors can enable the proper characterization of today’s advanced Wi-Fi chipsets and devices with its 195 MHz of VBW. This makes Boonton the only power measurement company that can measure the peak (envelope) power of Wi-Fi 6 signals that utilize 80 MHz channels and 160 MHz channels, as well as the 100 MHz channels of 5G new radio (NR) devices. In addition, the PMX40’s intuitive, multi-touch display enables fast configuration of up to four sensors, which makes it great for measuring MIMO devices. It is also essential to measure the time alignment between transmitted packets across channels when characterizing MIMO Wi-Fi chipsets. To address this, the PMX40 enables packet power measurements to be performed independently on multiple synchronous or asynchronous transmit chains with a common time base shared among sensors.

In addition to RF communications, the PMX40 can introduce a new approach to the installation, maintenance, and troubleshooting of complex radar systems. Secondary Surveillance Radar (SSR) is used to gather information about an aircraft, and relies on coded reply signals generated from an aircraft’s transponder in response to ground station interrogations. Safeguarding SSR design and operation remains essential for upholding the integrity and security of aviation, and therefore, SSR design, verification, troubleshooting, and maintenance are of the utmost importance in the commercial and military radar sector. Historically, SSR systems use different instrumentation on a task-specific basis, or the same equipment has been utilized throughout testing, but requires users to accept various compromises. The PMX40, however, can deliver superior performance within one instrument to meet the test challenges of SSR signals—without accepting performance tradeoffs.

The PMX40 can provide the precise timing and power measurements required for the accurately placed and shaped pulse trains of SSR systems. For example, the PMX40’s industry-leading, 3-ns rise time displays clean leading pulse edges within the SSR pulse train. The 5-ns time base and 100-ps cursor resolution enable acutely precise measurement timing, which facilitates the deliberate placement of pulses with a waveform that are integral to the coded SSR message. In addition, Boonton’s acquisition speed of 100,000 measurements per second makes the PMX40 a perfect choice to seamlessly capture SSR waveforms, uncovering crisp signal details and characteristics as well as more accurate power readings. In the end, Boonton provides more accurate pulse measurements and exceptional waveform fidelity with its class-leading rise time, time resolution, and acquisition speed on complex SSR signals.

Beyond the numerous applications that can benefit from Boonton’s uniquely capable RF power meter, the PMX40 also lends its flexibility to the broader lifecycle of product testing. Due to its ability to provide the benefits of traditional benchtop instruments, designers can use the PMX40 on their benchtop to complete test and measurement requirements and focus on the finalization of product development. As products move past R&D and into production, designers can disconnect the USB RF power sensors from the PMX40 and use them as standalone instruments to support production-level needs. As a result, the PMX40 and associated sensors provide the ultimate flexibility by delivering the continuity of test throughout the entire product lifecycle.

The Future of RF Power Measurement

Traditional benchtop meters have long been a mainstay for engineers, however, the introduction of USB power meters enhanced performance and portability, but replaced the traditional graphical user interface with a computer display. The Boonton PMX40 RF power meter and its associated sensors provide the ultimate combination by offering benchtop capability, touchscreen simplicity, and USB sensor performance and flexibility, realizing the future of RF power measurement.