Electrical test equipment mainly includes electronic measuring instruments and electronic application instruments, which refer to instruments, equipment, and systems that use electronic technology to measure and observe electric or non-electrical quantity, or light, electricity and measuring accessories supplied for measurement purposes. Measurements include data acquisition, storage, display, printing, drawing, processing, and transmission, and are information products.
Electrical test equipment has a wide range of application, therefore, can be classified into various instruments. Here we introduce two typical ones–digital multimeter and spectrum analyzer.
Digital multimeter (DMM), a modern multi-purpose electrical test equipment, generally includes functions such as ammeter, voltmeter, ohmmeter, etc., sometimes referred to as multimeter or triple-purpose meter. It has portable devices for basic troubleshooting, as well as devices placed on the workbench, with resolutions reaching seven or eight and are mainly used in physical, electrical, electronic and other measurement fields.
A spectrum analyzer is electrical test equipment that studies the spectral structure of an electrical signal, which is used to measure signal distortion, modulation, spectral purity, frequency stability, and intermodulation distortion. It is a versatile electronic measuring instrument used to measure parameters of certain circuits such as amplifiers and filters. It can also be called frequency domain oscilloscope, tracking oscilloscope, analytical oscilloscope, a harmonic analyzer, frequency characteristic analyzer or Fourier analyzer. Modern spectrum analyzers can display analysis results in an analog or digital manner and can analyze electrical signals in all radio frequency bands from very low frequency to sub-millimeter band below 1 Hz. The electrical test equipment has the functions of storage and calculation if the digital circuit and the microprocessor are used inside the instrument. When the standard interface is configured, it is easy to form an automatic test system.
Electrical test equipment and systems are in a chaotic period of coexistence of multiple buses and multiple interfaces: GPIB, VXI, MMS, PXI, PCI, CPCI, 1394, ISA, USB, SPI, SMB, I2C and other multi-bus coexist and the automatic test system has a distributed structure and a multi-bus structure, engulfing the computer and at the same time making itself a terminal product for a large computer network, and thus enabling long-distance control and long-distance transmission of test data, as well as sharing test hardware, software, technology and experience, and test information.
The widespread use of dedicated large-scale integrated circuits and programmable devices in the instrument not only protects their own technology patents but also changes the design ideas and design methods of digital circuits and computer systems. The use of DSP greatly simplifies the instrument IF circuit and improves the performance of the instrument.
What’s more, the use of computer systems and large-scale integrated circuits has completely changed people’s design ideas and has placed high demands on designers. More importantly, test instruments can directly use the latest computer results, so that the replacement speed of instrument synchronizes with the computer.
The overall technical level of domestic electrical test equipment is described as follows.
Universal benchtop instruments like microwave and millimeter-wave instruments are basically complete, the frequency of broadband coaxial instrument and millimeter wave guide instrument are up to 40GHz and 110GHz respectively and there is a whole range of fiber optic instruments with a communication instrument test rate of 2.4Gb/s; the digitizing rate of data acquisition instrument is 1GSa/s whose bandwidth is 500MHz.
VXI bus modular spectrum series has begun to take shape and can be used to build automatic test systems for RF, low frequency and data acquisition.
A batch of practical automatic test system and fault diagnosis has been developed and successfully applied to the development, production and maintenance testing of weapons and equipment with the circuit board fault diagnosis system achieving zero breakthroughs, indicating rapid growth in the technology of electrical test equipment.