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LabVIEW software powers innovative hardware to forever change instrumentation.
Much like every child’s first LEGO® set changes the way they imagine the world, 26 years ago National Instruments redefined the way we think about instrumentation with NI LabVIEW system design software. This year, NI is doing it again. The company is announcing a new class of instrumentation that frees test engineers from the limitations of vendor-defined instruments.
For many years, the basic model of instrumentation has remained largely unchanged. Engineers and scientists who want to make measurements first purchase fixed-function hardware from test and measurement suppliers. Then they use software, such as LabVIEW, on a standard desktop PC to extend the functionality of the hardware with signal processing, decision making, automation, and so on. Modular instruments have made a huge leap forward to become the de-facto standard for automated test systems. Yet even modular instruments have much of their functionality defined in the embedded firmware by the vendor; there are no means for you to change this firmware to suit your specific application.
However, across many other applications, the notion of fixed-function hardware is a legacy idea. Just ask the traditional cellphone providers struggling to rapidly adapt to software-based smartphones. Customers are demanding the ability to tailor their phones to match specific, individual needs using software running within these devices for more control. So why should test equipment be any different?
You can now take advantage of the most flexible, customizable test instrument ever created with the first software-designed instrument, theNI PXIe-5644R vector signal transceiver (VST).
Software-designed instruments feature three defining characteristics:
- Instrumentation hardware designed with open-source firmware based on FPGAs with out-of-the-box capabilities and rich sample code
- Well-built system design software to simplify the complexity of designing a custom hardware instrument
- A fundamental change in mindset from integrating a fixed-function device to designing exactly the instrument you need
Hardware With Open-Source, FPGA-Based Firmware
The new NI PXIe-5644R VST is designed to be smaller, lower cost, and more software-centric from the ground up. Based on industry-leading FPGA technology and the principle of open-source software and firmware completely written in LabVIEW, the VST hardware design pushes software as close as possible to the point where RF is converted to bits. By replacing fixed, vendor-defined hardware with a flexible, software-designed approach, the VST empowers test engineers to design exactly the instrument functionality they need.
The VST also helps RF engineers integrate up to five RF channels (each with RF generation and acquisition) into a single PXI chassis to address parallel testing needs and multiple input, multiple output (MIMO) applications. And while most legacy instrumentation solutions either provide a stimulus or measure a response, the VST combines an RF generator and analyzer in a single piece of hardware. Since both instruments are connected to a single FPGA and you have the ability to design the firmware in that FPGA, you can take advantage of closed-loop, system-level testing for the first time in RF test applications.
By combining a vector signal generator (VSG) and vector signal analyzer (VSA) with LabVIEW programmable real-time signal processing and control, the VST has the following features:
- A user-programmable FPGA
- Up to 85 MHz to 6 GHz frequency coverage
- 80 MHz real-time RF bandwidth
- Combined RF generator and analyzer plus a high-speed digital I/O port
- Low-cost, small footprint with three PXI Express slots
- Support for the latest wireless standards (802.11ac and LTE)
The design of the new NI PXIe-5644R VST connects a vector signal generator and analyzer to a single FPGA, so you can conduct closed-loop, system-level testing for the first time in RF test applications.
The Software That Powers the Vector Signal Transceiver
LabVIEW software combined with this new class of RF instrumentation empowers any engineer or scientist with RF knowledge to successfully design new features or enhance existing ones within the instrument. The software should first give you a way to design the software in the instrument at a system level, simplifying the complexity of the instrument into basic blocks for visualization and programming. Then the software should abstract the complexity of the software and firmware of an RF instrument at a fundamental level so that you can quickly understand the signal flow and know when and how to make additions and modifications. This helps you dig into each abstraction in a hierarchical way to access every function in the instrument.
The software should also be written in a language that can target both microprocessors and FPGAs so you can implement custom functionality in either location to use the inherent parallelism of these two processor architectures. Finally, the software should provide well-written reference designs that help customers familiar with more traditional instruments get immediate measurement results.
LabVIEW is uniquely suited to each of these requirements. It is equally adept at optimizing parallel programming for FPGAs on instruments, real-time processors, and software on the PC. The native dataflow programming model also provides an intuitive way to represent the movement of data from the I/O pin to your application. In this way, it helps solve the visualization problem and the implementation in the same diagram.
Field-proven LabVIEW has been used to program real-time systems since 1998 and to program FPGAs directly since 2003. In fact, LabVIEW has been meeting high-performance, mission-critical system design challenges for many years with products built on the LabVIEW reconfigurable I/O (RIO) architecture. Managing the collimators in the Large Hadron Collider at CERN, controlling laser cataract surgery in doctors’ offices around the globe, and defining future renewable energy source capture and distribution systems are all examples of LabVIEW use in critical, high-performance applications. The release of the NI PXIe-5644R VST now delivers this powerful capability to engineers in the RF space.
LabVIEW 2012 provides new templates and sample projects for most NI hardware devices, including the VST. The sample projects are designed to ensure the quality and scalability of a system and give you a powerful starting point for test applications by including software that enables the VST to work as a VSA plus a VSG for streaming embedded RF applications. All of the templates and sample projects are completely open source and include documentation that clearly shows how they work and the best practices for adding or modifying functionality.
To program the FPGA on the VST, you can use the LabVIEW FPGA Module, which also includes new capabilities for Version 2012. Features like the integration of floating-point math and analysis give you more options for code portability and reuse, and a new optimization technique helps you generate high-performance FPGA IP.
This LabVIEW 2012 diagram shows each part of the VST signal chain from signal acquisition to calibration to digital signal processing (DSP) and storage in memory.
A New Way to Think About Instrumentation
After years of learning to program vendor-defined instruments, you can now use the NI PXIe-5644R VST and LabVIEW to design your instrumentation.
With a software-designed approach, you no longer have to ask, “How do I make this box do what the vendor intended?” Instead, you can start asking, “If I can make this instrument do what I want, what will I do and how will I do it?”
Early access VST users are customizing the device in applications like these:
- Embedded protocols inside the instrument to build protocol-aware RF testers
- Integrated, real-time channel models to emulate RF device testing in the field
- Hardware-in-the-loop techniques to servo the nonlinearity of RF power amplifiers
- Software defined radios to prototype future RF standards
For some, the applications and potential are obvious; others will take a while to embrace this new approach. It’s similar to the advance of user-empowered smartphones. Looking back, you cannot imagine life without the diversity of applications solved through this single device, but when the first smartphone came to market, most of the world still viewed it as a simple telephone. How will your perceptions of instrumentation change once software-designed instruments become mainstream?
You can use the LabVIEW FPGA Module to program the FPGA on the VST with features like the integration of floating-point math and analysis.
—Charles Schroeder charles.schroeder@ni.com
Charles Schroeder is the director of test marketing at National Instruments.
This article first appeared in the Q3 2012 issue of Instrumentation Newsletter.
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