The Vector Signal Transceiver: What RF Engineers Need To Know
By Paul Kruczkowski, editor
During its NI Week conference earlier this month, National Instruments (NI) unveiled what it claims is the world’s first RF vector signal transceiver (VST), a unique combination of vector signal generator (VSG), vector signal analyzer (VSA), and 24-channel digital reconfigurable I/O (RIO) — all within a three-slot PXI module. I had the opportunity to review the new PXIe 5644R VST, and while the novel hardware configuration is certainly noteworthy, the real story here is the open, software-designed approach NI took to the instrumentation, which allows engineers to either select from predefined instrument models or configure the internal field-programmable gate array (FPGA) for their specific needs using NI’s LabVIEW FPGA programing module.
The software-designed instrument aspect of the VST provides tremendous flexibility to the user, through LabVIEW’s well-documented, easily modifiable source code. Using the LabVIEW system design software to modify the code on the fully programmable internal Xilinx Virtex-6 FPGA eliminates the need for users to be expert Very-high-speed integrated circuit Hardware Description Language (VHDL) programmers. The firmware is completely open to the user, so the instrument can be modified to function as required for the desired application. In addition, the user can program the FPGA to control data acquisition and signal generation, apply digital signal processing (DSP), and to control the device under test (DUT) through the digital I/O using the same LabVIEW interface.
Implementing software functions, often in parallel, on the FPGA hardware also reduces test time over processor-based instruments. This increase in measurement speed could allow for testing at every operating temperature or every gain setting of a device, or conduct other tests that previously were time prohibitive. The result is a better tested product with reduced time to market.
I asked Luke Schreier, senior group manager of NI’s Automated Test Group, if the NI PXIe-5644R signaled a shift toward more software-centric design of instrumentation. “The NI PXIe-5644R is just the first software-designed instrument developed by NI,” he replied. “We have plans to continue down this development path to add additional RF frequencies and bandwidths as well as other instrument categories. The empowering nature of a completely user-modifiable instrument is something that will prove useful in all areas of test and measurement.”
Empowering is a great way to describe the level of control the VST provides to engineers. In addition, users can also integrate the VHDL and LabVIEW FPGA Module code built on the NI LabVIEW RIO architecture directly into the VSS diagrams of AWR’s Microwave Office. This feature helps engineers use measurements in the design flow by executing LabVIEW code directly in the VSS environment, making their models even more accurate.
NI has taken modular test equipment to the next level by providing engineers with a tool that works out of the box using its preconfigured instrument profiles and offers the flexibility to configure the instrument and test environment to specific applications like 802.11ac testing or MIMO emulation. As NI expands this family of products, I’m sure the applications for software-designed instruments will be as diverse as the engineers using them. For more information on the performance specifications and possible applications of the VST, read NI’s tutorial or watch the video introduction (below).