Since the mid-1980s, virtual instrument technology has been combined with modular hardware, development software, and PC technology to enable users to create custom instruments using software. The software definition has greater flexibility than the vendor defines the capabilities of the bench instrument, and because of the PC-based technology, advanced functionality can be achieved at a faster rate.
Today, the use of virtual instrument technology in test applications has become mainstream. Most test industries have accepted the concept of virtual instrument technology, or prefer virtual instrument technology. For example, although the representative US military is not a leader in technology trends, it is also widely using virtual instrument technology. As the world's largest independent user of ATE (Automated Test Equipment), the U.S. Department of Defense has adopted a software-based instrument concept in the comprehensive instruments they are promoting. In a report submitted to Congress, the Ministry of National Defense pointed out: "In the development of comprehensive instruments, new commercial technologies can be used to configure the instrument in real time to achieve various test functions.... A single comprehensive instrument can replace multiple instruments. The function of an independent instrument, thereby reducing the size of logistics equipment and solving the problem of outdated equipment."[February 2002, the Department of Defense Technology Improvement Office submitted a report to Congress]. Comprehensive instrumentation and virtual instrumentation technologies have commercialized hardware and software processing features that combine the two to create user-definable instruments.
At present, thousands of large companies have begun to use virtual instrument technology. Many manufacturers only use hardware and software for virtual instrument technology in critical projects and large-scale product inspection applications. In the industrial field, virtual instrument technology has been used to automate oil drilling and refining, machine control in production, and even nuclear reactor control.
The problems of traditional instruments and innovators
As Clayton Christensen described in the book of the same name, traditional instruments will encounter “innovator problems†at the same time. Christensen describes this phenomenon as follows: The new breakthrough technology will change the market's prospects and eventually overturn the market leader's position. In fact, Christensen believes it is difficult to lead the market after the market leader’s position is overturned by new technology. In the field of test and measurement, traditional instruments use the existing architecture to improve the performance of measurements and continue to innovate in this direction. In the early days of virtual instrument technology, because of its low measurement performance, these breakthrough technologies did not pose much threat to traditional instrument manufacturers. Therefore, they largely ignored virtual instrument technology. The presence. However, by the late 1980s and early 1990s, virtual instrument technology began to be applied to measurements that required flexibility that could not be achieved through traditional methods. In the late 1990s and the 21st century, with the further improvement of the performance and accuracy of PC processors and commercial semiconductors, the measurement performance of virtual instrument technology has improved much more than before. Virtual instrument technology can now be comparable to, or even exceed, the measurement performance of traditional instruments, but it also has higher data rates, flexibility, scalability, and lower system costs.
In order to prove the principle of "innovators' dilemma" in the consumer goods market, we can compare the MP3 and traditional broadcast and test instrumentation media, such as CDs. At the beginning, traditional audio equipment manufacturers did not realize the threat of MP3 players - after all, MP3s reduced the quality of the sound, and you also needed PCs and specialized software to play them. On the other hand, CD players are easy to use and have dedicated operating interfaces (buttons and knobs). However, due to its advantages of easy sharing and portability, MP3 is still respected by some users in its early days despite its disadvantages. Over time, the quality of MP3 has been accepted and the software for playing MP3 has also been greatly developed. Now MP3 has become the mainstream and poses a great threat to the traditional audio recording and playback industry.
Although many traditional player makers eventually turned to adopt this breakthrough technology by developing players with MP3 capabilities (the Sony recently introduced the MP3W passband alkman), the new market has already been introduced by MP3 technology companies. leadership. For example, Apple has taken up 82% of sales of HDD music players [NPD, August 2004].
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 introduced products include an Ethernet-based "integrated instrument" and an arbitrary waveform generator compatible with PXI, which is an industry-standard virtual instrument technology platform. Recently, Agilent's John Stratton also expressed his support for a software-defined comprehensive instrument concept: “Compared to the current standard rack-based solutions, another option is to use comprehensive instruments. Comprehensive instruments use software algorithms and hardware modules instead of separation. Test Unit." [Military and Avionics, June 2004]. At the recent investor conference, Bill Sullivan, Agilent’s chief operating officer, stated that “turning to the use of modular software-based instruments allows users to easily configure and reuse, which will be the future direction of testing and measurement. ".
PC performance continues to innovate and reduce costs
Over the past two decades, the performance of PCs has increased 10,000 times. No other commercial technology has ever experienced such high performance growth. Since virtual instrument technology uses PC processors for measurement analysis, each time with the advent of a new generation of PC processors, virtual instrument technology can be used to realize new applications. For example, current 3 GHz PCs can be used to perform complex frequency domain and modulation analysis for communications test applications. Using the 1990 PC (Intel 386/16), a 65,000-point FFT (Fast Fourier Transform, a basic measurement for spectrum analysis) takes 1100 seconds. Now using a 3.4GHz P4 computer to achieve the same FFT takes only about 0.8 seconds [Ffbench, John Walker].
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 up to 3.2GBytes/s of bandwidth, enabling PC architecture to achieve ultra-high bandwidth measurements. Some vendors claim that high-speed internal buses will give way to external buses such as Ethernet and USB. Although there is no doubt that these external buses are suitable for specific application needs (such as Ethernet for distributed systems and USB for desktop connections), there are also high data transfer rate requirements. For example, a 100 MS/s 14-bit IF digitizer can generate 200 MB/s of data, which is higher than 80 MB/s of Gigabit Ethernet. For this reason, you will not see any Ethernet video cards in 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 via PCI Express. The software-based approach to virtual instrumentation can abstract the bus in application software to take advantage of all these buses—PCI, PCI Express, USB, and Ethernet.
Many traditional instrument manufacturers use the method of inserting test instruments into the 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 approach loses two key advantages of PC technology - one is the economies of scale of a desktop PC manufacturer like Dell, and the other is the ability to easily upgrade PCs to greatly improve measurement performance. Most oscilloscopes have a lifetime of 5 to 20 years, and a PC that has been in use for 20 years has no use value. In addition, as shown in Figure 1, the functionality of these devices is basically defined by the manufacturer - the user cannot use the firmware in the device to customize the measurement function.