Mobile Measurement Vehicle (MMV) Brings Signal Capture and Analysis on the Road
By Marty Mosier, Vice President of Business Development, X-COM Systems
Long-duration capture of RF and microwave signals “off the air” is an essential requirement in many applications, from surveillance to SIGINT, ELINT, spectrum monitoring and management, and testing of communications, radar, and EW systems. Most times these tasks can be performed in a fixed location, but some scenarios require them to be made at specific locations at specific times. To satisfy this requirement, X-COM Systems created its Mobile Measurement Vehicle (MMV), which integrates all required instruments and software as well as workstations and monitors, data link communications, and AC power generation within a standard utility van.
The MMV (Figure 1) is a fully-configured mobile platform that provides a diverse array of capabilities ranging from RF signal capture, storage, playback, and analysis, to spectrum monitoring, emitter direction-finding and geo-location, and on-site or mobile testing. It is a fully-integrated turnkey system built to meet specific customer requirements, and provides a comfortable working environment for two operators, a support team, and ample storage space (Figure 2). The MMV is available in multiple platforms including a diesel-powered two- or four-wheel-drive Mercedes-Benz Sprinter, diesel or gasoline powered two-or four-wheel-drive Chevrolet Series 350 cargo van, Nissan NV2500 van in standard or high-roof versions, and other vehicle options.
The instruments within the MMV can continuously capture RF spectrum with 100% probability of intercept for any signals of more than a few microseconds in duration for hours, days, or even weeks. Emitter direction-finding capabilities can be networked via data links to fixed-site spectrum monitoring systems in real time. The system can provide a permanent record of received RF signals, and geo-locate the source of signals of interest including GPS moving-map overlay capability.
For test range applications, the MMV can record the actual RF environment during exercises including both intentional and unintentional emitters for post-test analysis and anomaly troubleshooting. Unintentional emitters can be rapidly located using Angle of Arrival (AOA), Time Difference of Arrival (TDOA), and Power Difference of Arrival (PDOA) techniques. Onboard software can combine AOA, TDOA, and PDOA techniques in conjunction with other vehicles or fixed location monitoring receivers. Recorded signals can be recreated and retransmitted at their original or any other frequency with very high dynamic range and signal quality. Other applications include spectrum mapping, interference hunting, and providing detailed on-site analysis of spectrum capture files from operational exercises or surveillance activities.
In sensitive operational environments, the MMV can be configured using an unassuming rooftop luggage carrier in which antennas and other hardware are contained with no external markings. X-COM can also provide a team of measurement experts to work on site with customers to ensure that all activities are performed correctly and to act as an independent third party to certify results.
While X-COM has a variety of standard MMV measurement configurations, the van can accommodate nearly any measurement tools that a customer might require, including signal generators, spectrum analyzers, and other standard measurement equipment. However, the MMV’s core capabilities are based on X-COM’s instruments, including the IQC5000A RF spectrum capture and playback system, VSG5000A multi-channel, phase, coherent vector signal generator, Spectro-X signal analysis software, and RF Editor graphical signal and waveform editing software.
The IQC5000A is a compact, lightweight system for capturing and playing back RF and microwave signals over short durations or even very long time spans. The IQC5000A, which operates from either 120 VAC/240 VAC or a 12 VDC vehicle battery, is housed in an enclosure measuring only 12 x 3.5 x 10.5 in. and weighing less than 10 lb. It can record and play back one or two independent channels of RF signal activity over a bandwidth of 160 MHz that can be captured at frequencies from HF through millimeter wavelengths. The IQC5000A can internally store from 500 Gbytes to 2 Tbytes of signal capture data in removable solid-state drives, which provides dual-channel storage between 22 min. and 1.7 days depending on capture bandwidth. When configured using external storage up to 16 Tbytes, it can store from 2.7 hr. to 14 days of signal activity. All times are doubled for single-channel operation.
As the IQC5000A uses laboratory-grade signal analyzers from Agilent Technologies, Rohde & Schwarz, or Tektronix as its RF “front end”, it benefits from the instruments’ high spurious-free dynamic range and DSP-based amplitude and phase error correction. This allows the signal environment presented to the IQC5000A as I and Q signals to be a precise representation of what was actually recorded.
The VSG5000A has a frequency range of 50 MHz to 3 GHz and 6 to 18 GHz and can accurately simulate many types of systems using real-world signals. It combines four independent vector signal generators each with 110 MHz of bandwidth (440 MHz of total bandwidth) that can operate independently or together, along with solid-state storage for each channel that delivers 50 min. of recording time at maximum bandwidth, and measures only 21 x 17 x 7 in. Using the VSG5000A as a stimulus offers significant advantages over idealized signal files that cannot accurately depict the true nature of the electromagnetic environment that invariably includes noise, propagation effects, dense signal clusters, and interference.
X-COM’s Spectro-X software can simultaneously analyze four RF and microwave spectrum capture files and is the industry’s most comprehensive software designed to search for and analyze signals of interest within long-duration recordings of signal activity. New features in Spectro-X 4 .0 include simultaneous analysis of up to four recorded RF and microwave spectrum files with precise file alignment to plus or minus one sample, multi-domain correlated markers, and features that make the software more versatile and easier to use.
Spectro-X operates on files of signal activity captured over the air using a signal analyzer and X-COM’s IQC5000A or on custom spectrum files created in MATLAB or other software. It has four discrete search engines (carrier, wireless standard, arbitrary waveform, and pulse) that allow users to zoom in to specific sections of a file in frequency, time, or both, to find signals of interest. Results can be exported in a file format usable by vector signal analysis software for demodulation and detailed analysis. Pulsed waveforms can be characterized by their rise and fall times, pulse width, pulse repetition interval, peak and average power, and carrier frequency.
RF Editor is the only commercially-available Windows-based software that offers comprehensive editing capability for waveforms and waveform segments that have been captured over the air, offloaded from a signal analyzer, or created in programs such as MATLAB. Users can easily modify I&Q signals of any length, create entirely new ones, and build new signal files. RF Editor is an invaluable tool for modifying and building signal waveforms in the time and frequency domains and is integrated with Spectro-X.
Finally, the MMV typically incorporates X-COM’s high-performance SigAnalyst workstation that combines the performance of a fourth-generation Intel Core i7 quad-core processor with a high-speed backplane, DDR3 1333-MHz SDRAM, a wide range of storage options, enhanced graphics, and various communications interfaces. It typically includes Spectro-X as well as RF Editor and can be supplemented with other software tools. The workstation controls the entire measurement environment with an intuitive user interface that provides a breadth of capabilities. More information about the MMV is available by calling X-COM Systems at (571) 612-5475, by email at email@example.com, or by visiting the company’s website.
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