Synthetic instrumentation advances with RF down converter

  • 05-Sep-2008 08:24 EDT
The five Phase Matrix PXI modules handle a range of high frequencies and convert them for use on mainstream equipment.

Military suppliers are moving toward synthetic instruments that replace existing test and measurement equipment with flexible modular architectures. BAE Systems and Phase Matrix have teamed up to develop a synthetic down converter that is far smaller and faster than existing boxes.

The two completed the down converter to handle RF capabilities in a small form factor. That is done by leveraging PCs and other consumer technologies to create modular instruments that can be upgraded and reconfigured by adding and removing modules or circuit boards.

This approach, called synthetic instrumentation by many in the military and virtual instrumentation industry, is slowly gaining acceptance in defense projects. The concept lets engineers leverage rapidly advancing PC technologies.

One is the PCI bus used in PCs, which has been upgraded to PXI for instrumentation. That lets engineers who develop test systems to mix and match PXI boards in CompactPCI boxes, which have similarly been ruggedized for embedded applications.

That provides significant size and cost benefits compared to older VME-based technologies such as the VXI architecture now used to build many instrumentation systems.

“PXI is what makes this viable. This system is two-thirds the size of the VXI systems, and we also get a significant reduction in power,” said Wade Lowdermilk, an Engineering Fellow at BAE Systems.

PXI also provides significant speed enhancements. “In an apples-to-apples comparison, the old system took about six to eight seconds, and the new system takes 200 milliseconds,” Lowdermilk said. “In switching speed, we’re now in the sub-millisecond range. The old way, our switching speeds were around 25 milliseconds.”

Phase Matrix boards address the very high end of signal measurement, acquiring signals that range up to 26.5 GHz. Cards from general-purpose test suppliers typically stop at about 2.7 GHz, though National Instruments recently unveiled a 6.6 GHz module.

Phase Matrix offers five modules: RF input, microwave, low bandwidth (below 2.9 GHz), a local oscillator, and an output module. The down converter is used to test electronic warfare systems, avionics, and communications hardware.

Phase Matrix works closely with National Instruments, a virtual instrumentation company that has done extensive work in the PXI field. Its systems are widely used in a number of test facilities.

“We convert inputs down to baseband signals that people can work with,” said Mike Granieri, Vice President, Advanced Programs, at Phase Matrix Inc. “We work closely with National Instruments so data can easily be handled by their digitizers.”

The modules also gain flexibility by utilizing FPGAs. They also provide more speed, partially because architectures can be tweaked for the demanding task of handling high-frequency signals.

“We’re using the parallel processing capability of the FPGA, using a Xilinx-based board we developed,” Lowdermilk said.

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