The use of virtual instrumentation technology in testing applications has become mainstream. The vast majority of the testing industry has accepted the concept of virtual instrumentation or is inclined to adopt it. For example, the representative U.S. military, while not a leader in technology trends, is also widely using virtual instrumentation technology. As the world's largest independent user of ATE (Automated Test Equipment), the U.S. Department of Defense has adopted software-based instrumentation concepts in its comprehensive instrumentation programs. Currently, thousands of large companies have begun using virtual instrumentation technology. In production testing alone, industry leaders such as Lexmark, Motorola, Delphi, ABB, and Phillips have used both hardware and software of virtual instrumentation technology in critical projects and large-scale product testing applications. In the industrial sector, virtual instrumentation technology has been used in automation, oil drilling and refining, machine control in production, and even nuclear reactor control. 1. The Innovator's Dilemma In the field of testing and measurement, traditional instruments have continuously innovated by improving measurement performance using existing architectures. In the early days of virtual instrumentation technology, due to its relatively low measurement performance, it did not pose much of a threat to traditional instrument manufacturers, so they largely ignored its existence. However, in the late 1980s and early 1990s, virtual instrumentation technology began to be applied to measurements requiring flexibility that was impossible to achieve through traditional methods. By the late 1990s and early 21st century, with further improvements in the performance and accuracy of PC processors and commercial semiconductors, the measurement performance of virtual instrumentation technology had increased significantly. Now, virtual instrumentation technology can match or even surpass the measurement performance of traditional instruments, while offering higher data transfer rates, greater flexibility, scalability, and lower system costs. Agilent Technologies, a leader in the test and measurement industry, has begun to adopt the concept of virtual instrumentation technology. For example, Agilent's recent product offerings include a suite of Ethernet-based "comprehensive instruments" and an arbitrary waveform generator compatible with PXI, the industry-standard virtual instrumentation technology platform. Recently, John Stratton of Agilent also expressed support for the concept of software-defined integrated instruments: "An alternative to the current standard rack-mount solutions is to use integrated instruments. Integrated instruments use software algorithms and hardware modules to replace separate test units." At a recent investor conference, Bill Sullivan, COO of Agilent, stated, "The shift to modular instruments based on software configuration, which allows users to easily reconfigure and reuse them, will be the future direction of test and measurement." 2. Keys to the Success of Virtual Instrument Technology Virtual instrument technology has provided a new way to build test systems, thus impacting the traditional instrument market. The key to the success of virtual instrument technology lies in leveraging the rapidly evolving PC architecture, improving engineers' technical capabilities, reducing costs, adopting high-performance semiconductor data converters, and introducing system design software, which enables users to build virtual instrument technology systems. 2.1 Continuous Innovation in PC Performance and Reduced Costs Over the past two decades, PC performance has increased 10,000 times, a performance increase unmatched by any other commercial technology. Because virtual instrumentation technology uses PC processors for measurement and analysis, the advent of new-generation PC processors has enabled new applications. For example, a current 3GHz PC can be used for complex frequency domain and modulation analysis for communication testing applications. Using a 1990 PC (Intel 386/16), a 65,000-point FFT (a basic measurement for spectrum analysis) took 1100 seconds. Now, using a 3.4GHz P4 computer, the same FFT takes only about 0.8 seconds. Simultaneously, hard drive, display, and bus bandwidth have seen similar performance improvements. The new-generation high-speed PC bus, PCI Express, offers bandwidths up to 3.2 GBytes/s, enabling ultra-high bandwidth measurements using the PC architecture. Some manufacturers claim that high-speed internal buses will give way to external buses such as Ethernet and USB. Undoubtedly, these external buses are suitable for certain specific application needs (e.g., Ethernet is suitable for distributed systems, while USB is easy for desktop connections), but they also have the requirement for high-speed data transfer rates. For example, a 14-bit IF digitizer with a speed of 100 MS/s can generate 200 MB/s of data, which is higher than the 80 MB/s bandwidth of Gigabit Ethernet. For this reason, you won't see any Ethernet video cards on the market; even Gigabit networks are 30 times slower than PCI Express. In fact, Gigabit Ethernet interfaces and other peripherals are connected to the CPU via PCI Express. The software-based approach of virtual instrumentation technology abstracts the buses in the application software, thus utilizing all of these buses—PCI, PCI Express, USB, and Ethernet. Many traditional instrument manufacturers address this issue by embedding a PC within the instrument. These instruments typically have an embedded instrument processor and a standard PC motherboard connected to the instrument box via an internal bus. However, this approach loses two key advantages of PC technology—the economies of scale of desktop PC manufacturers like Dell, and the ease of upgrading the PC to significantly improve measurement performance. Furthermore, as shown in Figure 1, the functionality of these devices is manufacturer-defined, and users cannot customize the measurement functions using the firmware within the device. Figure 1. Comparison of Virtual Instrument Technology with Traditional Instruments as Defined by Manufacturers 2.2 Enabling Engineers and Researchers to Acquire More Technical Skills Technical skills have become a fundamental ability for individuals to establish themselves in society. Generally, our professional skills and computer knowledge are initially acquired in school. Recently, in a survey conducted by Lason L. Watai at Vanderbilt University, students agreed that "computer-based instruments are more user-friendly and easier to use than traditional desktop instruments." The sample size N=77 students (rating scale: 1=strongly disagree; 2=disagree; 3=partially agree; 4=agree; 5=strongly agree), and the students' average answer was 4.05. Overall, adopting computer-based virtual instrument technology can lead to more technical knowledge and programming skills. 2.3 Continuously Improving Commercial A/D and D/A Converters Another driving force behind the development of virtual instrument technology is the emergence of high-performance, low-cost A/D and D/A converters. Applications such as mobile phones and digital audio are constantly driving the development of these technologies. Virtual instrument technology hardware can utilize mass-produced chips as front-end components for measurement. These commercial technologies have developed according to Moore's Law—performance doubles every 18 months—while dedicated converter technologies have developed very slowly. Commercial semiconductor technology has ensured the rapid improvement of the digitization capabilities of virtual instrument technology. 2.4 Graphical system design software has also driven the development of virtual instrument technology. In traditional architectures, experts are needed to develop closed instrument functions and algorithms; however, for virtual instrument technology, the algorithms are open to users, who can define their own instruments. LabVIEW is such software. LabVIEW uses a graphical dataflow language, providing engineers and researchers with a very familiar interface—block diagrams. LabVIEW works like financial analysis using spreadsheets—it allows every computer user to build powerful financial models. The environment provided by LabVIEW allows all engineers and researchers to become measurement system design experts. 3. Prospects for System Design Using Virtual Instrument Technology Virtual instrument technology continues to expand its functionality and application scope. Now, LabVIEW can not only develop test programs on PCs, but also design hardware on embedded processors and FPGAs (Field Programmable Gate Arrays). This technology will ultimately provide a standalone environment that allows users to go from designing test systems to defining hardware functionality, as shown in Figure 2. Test engineers will be able to use appropriate functionalities for system-level design. When they need to define specific measurement functions, they can use the same software tools to "refine" to the appropriate level to define the measurement functionality. For example, they can develop LabVIEW programs to perform certain measurements, such as DC voltage and rise time, using modular instruments. When developing specialized measurements, they can also use LabVIEW to analyze raw measurement data to develop specialized measurements, such as peak detection. If, in some cases, they need to use new hardware functions to implement measurements, such as custom triggering, they can define a triggering and filtering scheme using LabVIEW and embed it into the FPGA on the instrument card. Figure 2 shows how the design of test systems is extended to hardware using simple system design tools. The functionality and performance of virtual instrument technology have been continuously improved, and it has now become a major alternative to traditional instruments in many applications. With further updates to PC, semiconductor, and software capabilities, the future development of virtual instrument technology will provide an excellent model for test system design and give engineers unparalleled power and flexibility in measurement and control.