New concepts and trends in electronic measuring instruments and automatic test systems

Preface

Since the beginning of the 21st century, the development of science and technology has been difficult to describe as changing with each passing day. New processes, new materials, and new manufacturing technologies have given birth to a new generation of electronic components, and at the same time have also prompted new concepts and new development trends in electronic measurement technology and electronic measuring instruments. This article intends to start with the three obvious characteristics of the development of modern electronic measuring instruments, and then introduce the concepts and basic technologies of the next generation of automatic test systems, and introduce the concept of synthetic instruments for readers' reference.

The development trend of modern electronic measuring instruments is that

the performance of the instrument is better

, the performance of the instrument is better, the measurement function is more powerful, and the measurement accuracy, test sensitivity, and dynamic range of the instrument have reached unprecedented heights. For example, the measurement sensitivity of Agilent's PSA spectrum analyzer is as high as -169dBm (close to the thermal noise in the physical world -174dBm), the dynamic range of PNA network analyzer is as high as 143dB, the resolution bandwidth of Agilent 83453A high-resolution spectrometer is 0.0001nm (sub-picometer) (breaking the barrier of picometer resolution bandwidth), the jitter of Agilent 86107A precision time base reference module is 1.7ps RMS for delays less than 100ns (breaking the bottleneck of picosecond jitter), and the DSO80000 series oscilloscope
has a single A/D chip with a real-time high sampling rate of 20GSa/s, making it the fastest sampling oscilloscope in the world (40GSa/s real-time sampling rate, 13GHz bandwidth). In addition, more powerful measurement functions are given to a single instrument, such as Agilent's 8960 series wireless integrated tester (integrating RF test and protocol test for mobile phones and base stations); ESG/PSG vector signal source can flexibly generate continuous wave/amplitude modulation/frequency modulation/phase modulation/pulse modulation, full-standard communication protocols (GSM/EDGE/WCDMA/TD2SCDMA/CDMAOne/CDMA2000/CDMA20001X2EV/Bluetooth/WLAN/PHS/PDC/NADC/DECT/TETRA, etc.), arbitrary waveforms and other signals for the future; MSO mixed signal oscilloscope (2/4 analog measurement channels + 16 logic analysis channels) enables a single instrument to have the functions of oscilloscope and logic analyzer at the same time; Infiniium oscilloscope with built-in VSA vector signal analysis software has also become the world's widest measurement and analysis bandwidth vector signal analyzer.

Instrument and computer integration

unprecedented integration of instrument and computer technology. First, more and more instruments are using Windows software and Intel chips as platforms, using Windows GUI and software based on military standards, using Windows software to replace the internal operating software of the instrument, and are easy to connect with MS office application software to give full play to its effectiveness. For example, Agilent's instruments can capture screen images with Word language, waveform data drawn with Excel language, and measurement data with Excel language. It is easy to freely download and upgrade the latest software version from the Internet, and use Windows Help to improve the convenience of instrument operation and learning. At the same time, touch screens are widely used, and voice control can solve the problem of operating instruments when both hands are occupied at the same time. Instrument operation can be controlled through the network, and test automation can be achieved based on MS Windows and MS Visual Studio. In addition, the VBA software inside the instrument can effectively help realize test automation in the production process.

Secondly, as computer technology is widely used in instruments, the instruments have more advanced connectivity. For example, most of Agilent's instruments have USB interfaces, LAN interfaces, and GPIB interfaces. At the same time, standard cursor indicators (mouse, tracking ball, touch keys, joystick, etc.) and other components (keyboard, CD RW drive, parallel interface for direct connection to printer, VGA output for external monitor, internal hard disk drive, etc.) are also installed. It is particularly worth mentioning that in special industries such as military industry, the security and confidentiality of test data are particularly important. For this reason, Agilent has designed a removable hard disk on the instrument (such as PNA vector network analyzer and Infiniium oscilloscope), so that after the staff completes the test task in the laboratory, they can remove the hard disk and transport the instrument to the test site (such as the battlefield) separately. The operator then takes out the hard disk carried with him and installs it into the instrument, and then conducts on-site measurements, thereby ensuring the security and confidentiality of the data.

Test and simulation software are widely used in instruments.

With the continuous increase in computer computing speed and data processing capabilities, and the widespread application of computer simulation technology, the combination of instrument hardware and test and simulation software is becoming closer and closer. First, the modular design of hardware enables different hardware modules to be combined with different software to form instruments with different functions and different test solutions. For example, Agilent's DAC-J broadband oscilloscope 86100C can be used as a jitter analyzer, broadband oscilloscope, digital communication analyzer, and time domain reflectometer by inserting different modules and matching different software. In addition, the test instruments with VXI structure fully explain the flexible configuration and application of modular structure instruments. Secondly

, the concept of software radio has a new interpretation and practical application. Agilent's 89601A vector analysis software is the best example of this concept. It uses the powerful mathematical operation and data processing capabilities of computers to fully display a large number of digital signal processing functions and data analysis functions in computer software. By combining with different data acquisition front ends (such as VXI structure vector signal analyzers, spectrum analyzers, and Infiniium digital oscilloscopes), vector signal analyzers with different functions are combined.

At the same time, the captured signals and data analysis results can be used as data input sources for EDA simulation software (such as Agilent's ADS advanced design simulation software) to drive ADS advanced design simulation software to perform component and system-level simulation; and the simulation results of ADS advanced design simulation software can be sent to Agilent's ESG/PSG vector signal source to generate signals that are captured and analyzed by VSA vector signal analyzer, which in turn can be used to verify the data between product design and real products, that is, to achieve the organic combination of design, simulation, measurement and verification. EDA software represented by Agilent ADS advanced design simulation software achieves the organic combination of measurement domain and simulation domain through dynamic linking with Agilent's test instruments (including: spectrum analyzers, network analyzers, signal sources, oscilloscopes, logic analyzers, etc.), and builds a bridge between design, simulation and verification, thereby accelerating design, improving design quality, and improving semi-physical simulation methods for systems and components, so as to achieve the purpose of rapidly expanding measurement solutions that meet needs.

Development History and Current Status of Automatic Test Systems

With the continuous improvement and perfection of the functions of measuring instruments,
the establishment and development of related automatic test systems (especially military ATS test systems) have also experienced a development process from desktop instrument ATS systems to card instrument ATS systems, and from card instrument ATS systems to ATS systems that are a mixture of card instruments and desktop instruments. So far, the combination of VXI structure instruments (mainly for digital signal measurements with large channels) and GPIB standard desktop instruments (mainly for RF/microwave signal measurements with strict performance requirements) to form an ATS test system has become the mainstream principle and model generally followed by military ATS test systems. This has a lot to do with the use of COTS (Commercial Off-the-Shelf) popular commercial instruments to build military ATS test systems advocated by military users represented by the United States in the 1990s, which can greatly reduce the cost of the establishment, development, maintenance, replacement and upgrade of the entire test system. [page]

However, due to the relatively long system development and certification cycles in the military industry, the system maintenance and support cycles are usually 10 to 20 years, while the development of civilian technology is changing with each passing day, and the update speed of popular commercial instruments is getting faster and faster. Some COTS products have been obsolete and discontinued before they are used on a large scale in the military industry. The maintenance and support of the finalized test system has become the biggest problem faced by military customers, especially the maintenance, support and update of the test software (TPS) developed based on specific hardware. This is also a huge challenge. The same problem has been encountered in the Chinese customer base. How to achieve hardware interchangeability and software interoperability has become the key to ensuring the vitality and life cycle of the entire system. At the same time, the military ATS test system must meet its reliability, mobility and flexibility requirements, and reduce the cost of development and maintenance as much as possible, save human resources, improve the efficiency of hardware on-site replacement and maintenance center replacement, and improve the weapon system to quickly respond to the strategic requirements of regional and even global support.

Next-generation automatic test system

Next-generation test technology and test system standards

In the past year, users and instrument manufacturers led by the United States have proposed a new test instrument concept and technology to solve the problems caused by COTS instruments and meet the development requirements of future test systems. This technology is called NxTest, which is a modular synthetic instrument based on LAN. In September 2004, Agilent Technologies and VXI Technology launched the next-generation modular platform standardization based on LAN for automatic test systems - LXI.

LXI (LAN extension for instruments) not only provides embedded measurement technology and PC standard I/O connectivity for rack and stacked instruments, but also realizes the modular characteristics of systems based on plug-in instruments and reduces the size. For R&D and manufacturing engineers who develop electronic products for the aviation/defense, automotive, industrial, medical and consumer electronics markets, LXI's compact and flexible packaging, high-speed input/output and reliable measurement functions effectively meet their needs. While the VXI bus provides an ideal standard for all high-density, high-speed applications, LXI combines the advantages of both VXI and Ethernet, providing users with a good high-performance instrument platform that meets application requirements that VXI does not usually meet. LXI, based on the LAN structure, for example, lays the foundation for the implementation of long-life instruments in the aerospace and defense industries. LXI has no bandwidth, software, or computer backplane structure limitations. It can take advantage of the increasing throughput of Ethernet and provide an ideal solution for engineers facing the challenges of the next generation of automatic test systems. The

LXI standard will be managed by the LXI Association. The LXI Association is a non-profit organization composed of major test and measurement companies. The group's goal is to develop, support, and promote the LXI standard. Agilent Technologies and VXI Technology have used their long history of modular instrument design to launch the LXI platform, which is an inevitable and feasible step in the development of open standard instruments used in test systems. Ethernet (LAN) has become a widely recognized communication interface in the industry because it is built into almost every computer. Internet hardware prices are constantly decreasing, speeds are constantly increasing, and local area networks provide peer-to-peer communication that is not provided in other point-to-point interface standards. Test and measurement engineers are increasingly aware of the benefits of using high-speed LANs to replace proprietary test and measurement interfaces (such as GPIB). The industry needs lower costs, higher bandwidth, and faster data transfer rates, which poses a challenge to proprietary test and measurement interfaces.

LXI test and measurement modules are optimized for use in design verification or manufacturing test systems. The ability to connect to a LAN allows each module to be installed anywhere in the world and accessed from anywhere in the world. Unlike modular components that use expensive power supplies, backplanes, controllers, MXI cards, and cables, LXI modules come with processors, LAN connections, power supplies, and trigger inputs. LXI modules can be full-width or half-width, with a height of one rack unit or two rack units, making it very easy to mix and match functions. Signal inputs and outputs are located on the front, and the LAN and input AC power are located on the back of each LXI module. LXI modules are controlled by computers and do not require displays, buttons, and dials that are equipped with traditional rack and stacked instruments. LXI modules use standard network browsers to diagnose problems and use IVI-COM drivers for communication, simplifying system integration.

Features of LXI Instruments

LXI instruments have the following five major features:

(1) Open industrial standards

LAN and AC power are the most stable and longest-lived open industrial standards in the industry. Due to their low development cost, manufacturers can easily migrate existing instrument products to the LAN-Based instrument platform
.

(2) Backward compatibility

Because LAN-Based modules only occupy 1/2 of the standard cabinet width, they are smaller in size than scalable (VXI/PXI) instruments. At the same time, upgrading existing ATS does not require reconfiguration and allows expansion to large card-based instrument (VXI/PXI) systems.

(3) Low cost

While meeting the requirements of military and civilian customers, the core technology of existing desktop instruments is retained and combined with the latest technology to ensure that the cost of new LAN-based modules is lower than that of corresponding desktop instruments and VXI/PXI instruments.

(4) Interoperability

As a synthetic instrument (Synthetic Instruments) module, only about 30 to 40 general modules are needed to meet the main test needs of military customers. Such a relatively small number of module types can be efficiently and flexibly combined into various test units for target services, thereby completely reducing the size of the ATS system and improving the mobility and flexibility of the system.

(5) Timely and convenient introduction of new technologies

Since these modules have complete I/O definition documents (defined by military standards), the upgrade of modules and systems only needs to verify whether the new technology covers all the functions of the products they replace. In this way, synthetic instruments (Synthetic Systems) will achieve the following five major goals: ① Very long product and system support cycle, application software will no longer rely on specific hardware. ② Very small system size, the instrument does not contain redundant display, input and other aesthetic design parts. ③ Clear and clear application, consistent instrument interface, quick and convenient upgrade. ④ The system life cycle is consistent with the product life cycle. ⑤ Supplier independence, there is no direct connection between measurement hardware and measurement technology.

Looking to the future

In summary, with the development of chip technology and DSP technology, electronic measurement instruments in the 21st century will achieve unprecedented high performance. With the further integration of computer technology and instruments, the instrument's ease of operation, upgradeability, measurement capability, data processing and analysis capabilities have all been greatly improved. At the same time, software radio is increasingly being applied to various fields, and simulation technology will provide users with more powerful and convenient tools for design and verification. The automatic test system has experienced a development process from GPIB system to VXI system, and from VXI system to VXI and GPIB hybrid system. More and more military users hope to have a long-life and high-performance system standard system to bear the pressure of increasingly complex testing pressure and maintenance costs. Facing future challenges, LXI instruments will inherit the existing test technology and bring new hope for the innovation of the next generation of test technology and test instruments, especially ATS test systems. (end)