Since the mid-1980s, virtual instrument technology has combined modular hardware, development software, and PC technology, allowing users to build custom instruments through software. Software definition has greater flexibility than the way manufacturers define desktop instrument functions, and because it is based on PC technology, it can implement advanced functions at a faster rate.
--- Virtual instrument has become the mainstream technology in the current test application, most testing industries have accepted the concept of virtual instrument technology, or tend to adopt virtual instrument technology. Comprehensive instrument and virtual instrument technology have the characteristics of commercial hardware and software processing. Combining the two can create user-defined instruments.
Problems of traditional instruments and innovators
--- New breakthrough technologies will change the market's prospects and eventually overthrow the market leader's status. In other words, traditional technologies will encounter "innovator's problems." In the field of test and measurement, traditional instruments use existing frameworks to improve measurement performance and continue to innovate in this direction. 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 traditional manufacturers largely ignored the existence of virtual instrument technology. However, by the late 1980s and early 1990s, virtual instrument technology began to be used in measurements that required flexibility, and these applications could not be achieved by traditional means. By the end of the 1990s and the 21st century, with the further improvement of the performance and precision of PC processors and commercial semiconductor chips, the measurement performance of virtual instrument technology has been much improved than before. Now, the virtual instrument technology can match the measurement performance of traditional instruments, even exceed them, and it also has higher data transmission rate, flexibility, scalability and lower system cost.
--- In the test and measurement market, industry leader Agilent has also begun to adopt the concept of virtual instrument technology. For example, Agilent ’s recently launched products include a set of Ethernet-based "comprehensive instruments" and an arbitrary waveform generator that is compatible with PXI, which is an industry-standard virtual instrument technology platform. The shift to the use of modular instruments based on software configuration allows users to easily configure and reuse repeatedly, which will be the future development direction of test and measurement.
The key to the success of virtual instrument technology
--- Virtual instrument technology provides a new way to establish a test system, thus affecting the traditional instrument market. The key to the success of virtual instrument technology is to use the rapidly developing PC architecture, improve the technical capabilities of engineers, reduce costs, use high-performance semiconductor data converters, and introduce system design software. System design software can make the majority The user establishes a virtual instrument technology system.
PC performance continues to innovate and reduce costs
--- In the past 20 years, the performance of the PC has been improved by 10,000 times. No other commercial technology has ever had such a high performance growth. Because the virtual instrument technology uses a PC processor for measurement and analysis, each time with the emergence of a new generation of PC processors, new applications can be realized using virtual instrument technology. For example, the current 3GHz PC can be used for complex frequency domain and modulation analysis. In 1990, a 386-processor PC was used to perform 65 000-point FFT (Fast Fourier Transform, basic measurement for spectrum analysis) in 1100 seconds. But now it takes about 0.8s to achieve the same FFT using a 3.4GHz P4 computer.
--- At the same time, hard disk, display and bus bandwidth have similar performance improvements. The new generation of high-speed PC bus PCI Express can provide a bandwidth of up to 3.2GB / s, which can use the PC architecture to achieve ultra-high bandwidth measurement. Some manufacturers claim that the high-speed internal bus will give way to external buses such as Ethernet and USB. Although these external buses are suitable for some specific application requirements (such as Ethernet for distributed systems, and USB for easy desktop connection), there are also high-speed data transmission rate requirements. For example, a 100MSPS 14-bit IF digitizer can generate 200MB / s of data, which will be higher than the 80MB / s bandwidth of Gigabit Ethernet. For this reason, users will not see any Ethernet video cards in the market, and 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 utilize all these buses, including PCI, PCI Express, USB, and Ethernet.
--- Many traditional instrument manufacturers use embedded PC in the instrument to solve this problem. These instruments usually have an embedded instrument processor and a standard PC motherboard connected to the instrument box via an internal bus. However, this method loses two key advantages of PC technology. One is the economies of scale of desktop PC manufacturers like Dell. The other is that it can easily upgrade the PC to greatly improve the measurement performance. The service life of most oscilloscopes is 5 to 20 years, and a PC that has been used for 20 years is no longer useful. In addition, as shown in Figure 1, the functions of these devices are basically defined by the manufacturer, and users cannot use the firmware in the device to customize the measurement functions.
Enable users to acquire more technical talents
--- Technical talents have become the basic ability of individuals based on society. Compared with traditional desktop instruments, computer-based instruments are more friendly and easier to use. In the past 10 years, users have gained more technical talents. Using computer-based virtual instrument technology can enable them to obtain more technical knowledge and programming skills.
A / D and D / A converters with ever-increasing performance
--- Another driving force for the development of virtual instrument technology is the emergence of high-performance, low-cost A / D and D / A converters, and 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 are developed in accordance with Moore's Law, while dedicated converter technologies are developing very slowly, and their performance improvement is shown in Figure 2.
Graphical system design software
--- Finally, because it can provide an intuitive interface to design customized instrument systems, system design software also promotes the development of virtual instrument technology. New breakthrough innovations can make the process of developing equipment no longer require "experts." In the traditional framework, experts are required to develop closed instrument functions and algorithms; for virtual instrument technology, 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 a very familiar interface for engineers and researchers. LabVIEW works like financial analysis using spreadsheets. LabVIEW provides an environment that allows all engineers and researchers to become measurement system design experts.
Prospects of System Design with Virtual Instrument Technology
--- Virtual instrument technology continuously expands its functions and applications. Now LabVIEW can not only develop test programs on PCs, but also design hardware on embedded processors and FPGAs. This technology will eventually provide such an independent environment, allowing users to design the test system to define the function of the hardware, as shown in Figure 3. Test engineers will be able to use appropriate functions for system-level design. When they need to define specific measurement functions, they will also be able to use the same software tools to "refine" Korea Micco MCSCO | Japan Universal MULTI | Japan Sanwa SANWA | Japan Yokogawa YOKOGAWA | Japan Hioki | Kano Japan KANOMAX | Japan New Universe COSMOS | Japan Kai Shi KAISE | Japan Xin Bao SHIMPO | to the appropriate level to define the measurement function. For example, engineers can develop LabVIEW programs to use modular instruments to make certain measurements, such as DC voltage and rise time. When engineers need to develop specialized measurements, they can also use LabVIEW to analyze the original measurement data to develop specialized measurements, such as peak detection. If in some cases they need to use some new hardware features to implement the measurement, such as customized triggers, then they can use LabVIEW to define a trigger and filter scheme and embed it in the FPGA on the instrument card.
Virtual instrument technology has become mainstream
--- The function 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 powerful functions and flexibility in measurement and control.
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