Building a new type of instrument: software-defined instrumentation

Just as every child's first set of LEGO® toys changed their understanding of the world, 26 years ago, National Instruments changed people's understanding of instruments through NI Labview system design software . This year, NI will repeat history again and release a new instrument to help test engineers break free from the constraints of manufacturer-defined instruments .

For many years, the basic model of instrumentation has not changed much. Engineers and scientists who need to perform test work must first purchase fixed-function hardware from test and measurement vendors, and then use software such as LabVIEW on a standard desktop computer to expand the functionality of the hardware through signal processing, decision making, automation, etc. The emergence of modular instruments is a huge leap forward and has become the established standard for automated test systems. However, many functions in modular instruments have been defined by the manufacturer in embedded firmware, and users cannot change the firmware to meet specific application requirements.

However, for many other applications, the fixed-function hardware philosophy is outdated. Traditional mobile phone manufacturers are working hard to quickly move to software-based smartphones. Customers want more control over the software running on their devices, so that their phones have features that meet their specific personal needs. Test equipment is no exception.

You can now experience the most flexible custom test instrumentation available today with the first software-defined instrument , the NI PXIe-5644R vector signal transceiver ( VST ) .

Software-designed instruments have three essential characteristics:

 Instrument hardware designed using FPGA-based open source firmware , ready to use, and includes rich example code

Excellent  system design software can reduce the complexity of custom hardware instrument design.

 It is a fundamental change of concept from integrating a fixed-function device to designing the instrument that the user really needs.

Use open source FPGA firmware based hardware

The new NI PXIe-5644R VST is smaller, lower cost, and more software-centric. Based on industry-leading FPGA technology and open source software and firmware written entirely in LabVIEW , the VST hardware design can convert RF into bits as much as possible. Using flexible software design to replace fixed, factory-defined hardware, the VST helps test engineers design the instrument functions they really need .

Figure 1 : The NI PXIe-5644R VST design connects a vector signal generator and analyzer to an FPGA , allowing users to perform closed-loop system-level testing tasks in their first RF test applications.

VST can also help RF engineers integrate up to five RF channels (each with RF generation and acquisition functions) into a PXI chassis to meet parallel test requirements and multiple-input multiple-output ( MIMO ) application requirements. Most traditional instrument solutions provide a stimulus or measure a response; while VST combines the RF generator and analyzer on a single hardware. Because both instruments are connected to an FPGA , users can design firmware in this FPGA , allowing them to use closed-loop system-level test functions in their first RF test application.

By combining a vector signal generator ( VSG ) and vector signal analyzer ( VSA ) with LabVIEW programmable real-time signal processing and control, the VST provides the following features:

A  user-programmable FPGA

Covers  frequency range from 85 MHz to 6 GHz

 80 MHz real -time RF bandwidth

Combines  an RF generator and analyzer, and a high-speed digital I/O port

Use  three PXI Express slots to reduce cost and footprint

Supports  the latest wireless standards ( 802.11ac and LTE )

Software makes vector signal transceivers more powerful

Figure 2 : This LabVIEW 2012 block diagram shows each part of the VST signal chain, from signal acquisition to calibration to digital signal processing ( DSP ) and storage in memory.

LabVIEW software combined with this new RF instrument can help all engineers and scientists with RF knowledge successfully design new features or improve the performance of existing instruments . The software should first allow customers to design software at the system level in the instrument , complete graphics and programming with basic modules to simplify the complexity of the instrument . Next, the software should abstract the complexity of RF instrument software and firmware at the bottom level, allowing users to quickly understand the signal flow and know when to make additions or modifications. This can help customers gain a deep understanding of each abstract process in a hierarchical manner and access every function in the instrument .

The language in which the software is written should be compatible with both microprocessors and FPGAs , allowing users to implement custom functions anywhere they want by taking advantage of the inherent parallelism of both processor architectures. Finally, the software should provide good reference designs to help customers who are more familiar with traditional instrumentation to immediately obtain measurement results.

LabVIEW can meet all the above requirements. It can optimize the parallel programming of FPGA , real-time processor and PC software on the instrument . Its natural data flow programming model can also provide an intuitive way to display the process of data input from I/O pins to the application. This method can solve the problem of visualization and can be implemented in the same flowchart.

Since 1998 , LabVIEW has been proven to be used for real-time system programming, and since 2003 , LabVIEW has been able to program FPGAs directly . In fact, LabVIEW has been able to meet the challenges of high-performance, deterministic system design through products based on LabVIEW 's reconfigurable I/O ( RIO ) architecture for many years. Managing collimators in CERN 's Large Hadron Collider, controlling lasers for cataract surgery in doctors' offices around the world, and building future renewable energy acquisition and distribution systems are all examples of LabVIEW used in deterministic, high-performance applications. The release of the NI PXIe-5644R VST also brings these powerful features to engineers in the RF field.

LabVIEW 2012 provides new templates and example projects that can be applied to most NI hardware devices, including VST . Example projects can ensure the quality and scalability of the system and include software that enables VST to work as VSA and VSG in embedded RF streaming applications, giving users a powerful starting point for test applications. All templates and example projects are open source and include relevant documentation that clearly explains how to apply them and best practices for adding or modifying functionality.

Figure 3 : Users can use the LabVIEW FPGA Module to program the FPGA on the VST , which features integrated floating-point calculations and analysis.

Users can use the LabVIEW FPGA module ( which has added many new features in the latest 2012 version) to program the FPGA on the VST . Features such as integrated floating-point calculations and analysis can provide users with more options for code porting and reuse, and provide a new optimization technology to generate high-performance FPGA IP cores.

A new understanding of instruments

After decades of learning how to program factory-defined instruments , users can now design their own instruments using the NI PXIe-5644R VST and LabVIEW .

With a software design approach, users no longer have to ask, “How can I make this box do what the manufacturer pre-designed it to do?” Instead, users begin to ask, “If I could make this instrument do what I want it to do, what would I ask it to do, and how would I do it?”

Early adopters of VST used their devices for the following applications:

Embed  protocols into instruments to build protocol-aware RF testers

Simulate on-site RF device testing through  integrated real-time channel models

Use hardware - in-the-loop technology to servo the nonlinearity of RF power amplifiers

Software  -defined radio for prototyping with future RF standards

For some, the applications and future developments are obvious; for others, it will take a while to accept this new approach. Think of it like the advent of user-enabled smartphones. Looking back now, we can’t imagine life without smartphones to enable countless applications, but when the first smartphone came out, most people just thought of it as a regular phone. How will your view of instrumentation change once software-defined instrumentation becomes mainstream?