Virtual instrument technology has become the mainstream technology in the testing industry

Nowadays, the use of virtual instrument technology in test applications has become mainstream. Most of the test industry has accepted the concept of virtual instrument technology or tends to adopt virtual instrument technology. For example, the representative US military, although not a leader in technology trends, is also widely using virtual instrument technology. As the world's largest independent user of ATE (automated test equipment), the US Department of Defense has adopted the concept of software-based instruments in the comprehensive instruments they promote. At present, thousands of large companies have begun to use virtual instrument technology. In production testing alone, industry leaders such as Lexmark, Motorola, Delphi, ABB and Phillips have used virtual instrument technology hardware and software in critical projects and large-scale product testing applications. In the industrial field, virtual instrument 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 test and measurement, traditional instruments have been continuously innovating in this direction by using existing architectures to improve measurement performance. In the early days of virtual instrument technology, due to its relatively low measurement performance, it did not pose much threat to traditional instrument manufacturers, so they largely ignored the existence of virtual instrument technology. However, in the late 1980s and early 1990s, virtual instrumentation began to be applied to measurements that required flexibility, which could not be achieved through traditional methods. In the late 1990s and 2000s, as the performance and accuracy of PC processors and commercial semiconductors continued to improve, the measurement performance of virtual instrumentation was much higher than before. Now, virtual instrumentation can match or even exceed the measurement performance of traditional instruments, but also has higher data transfer rates, flexibility, scalability and lower system costs.

Agilent, a leader in the test and measurement industry, has begun to adopt the concept of virtual instrumentation. For example, Agilent's recently launched products include a set of Ethernet-based "comprehensive instruments" and arbitrary waveform generators compatible with PXI, an industry-standard virtual instrumentation platform. Recently, John Stratton of Agilent Technologies also expressed support for the concept of software-defined integrated instruments: "An alternative to the current standard rack-based solution 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, Agilent's COO, said, "The shift to modular instruments based on software configuration, which allows users to easily reconfigure and reuse, will be the future development direction of test and measurement." 2

The key to the success of virtual instrument technology

Virtual instrument technology provides a new way to build test systems, thereby affecting the traditional instrument market. The key to the success of virtual instrument technology is to take advantage of the rapidly developing PC architecture, improve the technical capabilities of engineers, reduce costs, use high-performance semiconductor data converters, and introduce system design software, which enables users to build virtual instrument technology systems.
2.1 PC performance continues to innovate and reduce costs

In the past two decades, the performance of PCs has increased by 10,000 times, and no other commercial technology has ever achieved such a high performance growth. Because virtual instrumentation uses PC processors to perform measurements and analysis, new applications can be realized with the emergence of new generations of PC processors. For example, today's 3GHz PCs can be used to perform complex frequency domain and modulation analysis for communication test applications. Using a 1990 PC (Intel 386/16), a 65,000-point FFT (a basic measurement for spectrum analysis) took 1100 seconds. Today, using a 3.4GHz P4 computer to perform the same FFT takes only about 0.8 seconds. At the same time, hard disks, displays, and bus bandwidths have similar performance improvements. The new generation of high-speed PC buses, PCI Express, can provide bandwidths of up to 3.2GBytes/s, allowing ultra-high bandwidth measurements to be made 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 application requirements (such as Ethernet for distributed systems and USB for easy desktop connections), but there is also a demand for high-speed data transfer rates. For example, a 100MS/s 14-bit IF digitizer can generate 200MB/s of data, which is higher than the 80MB/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, the Gigabit Ethernet interface and other peripherals are connected to the CPU through PCI Express. The software-based approach of virtual instrument technology can abstract the bus in the application software to take advantage of all of these buses - PCI, PCI Express, USB and Ethernet. Many traditional instrument vendors have adopted the approach of embedding PCs in instruments to solve this problem. These instruments usually have an embedded instrument processor and a standard PC motherboard connected to the instrument box through an internal bus. However, this approach loses two key advantages of PC technology - the economies of scale of desktop PC vendors such as Dell, and the ability to easily upgrade the PC to significantly improve measurement performance. In addition, as shown in Figure 1, the functions of these devices are defined by the manufacturer, and users cannot use the firmware in the device to customize the measurement function. [page]

2.2 Enable engineers and researchers to acquire more technical skills

Technical skills have become the basic ability for individuals to gain a foothold in society. Generally speaking, our professional skills and computer knowledge are initially acquired in school. In a recent survey conducted by Lason L. Watai of Vanderbilt University, students all agreed with the statement that "Compared with traditional desktop instruments, computer-based instruments are more friendly and easier to use." The sample size N=77 students (rating scale: 1=strongly disagree; 2=disagree; 3=partially agree; 4=agree; 5=strongly agree), the average student answer was 4.05. Overall, the use of computer-based virtual instrument technology can gain more technical knowledge and programming skills.

2.3 Continuously improving commercial A/D and D/A converters

Another driving force for 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 continue to promote the development of these technologies. Virtual instrument technology hardware can use mass-produced chips as front-end components for measurement. These commercial technologies develop according to Moore's Law-performance doubles every 18 months-while dedicated converter technology develops very slowly. Commercial semiconductor technology ensures the rapid improvement of the digital capabilities of virtual instrument technology.

2.4 Graphical system

System design software has also promoted the development of virtual instrument technology. In the traditional framework, experts are needed to develop closed instrument functions and algorithms; for virtual instrument technology, the algorithms are open to users, and users can define their own instruments. LabVIEW is such software. LabVIEW uses a graphical data flow language, which can provide engineers and researchers with a very familiar interface - the program flowchart. LabVIEW works like using a spreadsheet for financial analysis - it allows every computer user to build a powerful financial model. The environment provided by LabVIEW can make all engineers and researchers become measurement system design experts.

3 Prospects of system design using virtual instrument technology

Virtual instrument technology continues to expand its functions 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 eventually provide such an independent environment that allows users to design test systems from defining hardware functions, as shown in Figure 2. Test engineers will be able to use appropriate functions for system-level design. When they need to define specialized measurement functions, they can use the same software tools to "fine-tune" to the appropriate level to define the measurement functions. For example, LabVIEW programs can be developed to use modular instruments to perform certain measurements, such as DC voltage and rise time. When they need to develop specialized measurements, they can also use LabVIEW to analyze the raw measurement data to develop specialized measurements, such as peak detection. If in some cases they need to use some new hardware functions to implement measurements, such as customized triggers, they can use LabVIEW to define a trigger and filtering scheme and embed it in the FPGA on the instrument card.

The functions and performance of virtual instrument technology have been continuously improved, and now it has become the main alternative to traditional instruments in many applications. With the further update of PC, semiconductor and software functions, the future development of virtual instrument technology will provide an excellent model for the design of test systems and enable engineers to obtain unparalleled power and flexibility in measurement and control.