Understand the development history of signal spectrum analyzers and enter the world of spectrum analyzers

A spectrum analyzer is a tool for studying the energy distribution of a given electrical signal on the frequency spectrum. It is basically a superheterodyne receiver with a swept local oscillator. The spectrum analyzer can decompose complex signals into single components and display the corresponding relationship between amplitude and frequency. It can measure the frequency and amplitude of the signal. In addition, the spectrum analyzer can also provide RF packets such as modulated signals. Measurement of various parameters such as network, signal distortion, intermodulation and noise sidebands.

Since the invention of the cathode ray tube in the late 1930s, engineers have used the first spectrum analyzers to observe the relationship between signal power and frequency, helping them achieve basic functions in radar development. The spectrum analyzers of the 1940s were laboratory creations based on swept-frequency radio frequency receivers. Desktop spectrum analyzers really appeared in the 1950s and 1960s. This analog swept frequency receiver had a large number of switches and control knobs, complicated operation, and completely manual control of sweep speed, frequency range, resolution and attenuation. Since the parameters interact with each other, the operator must carefully select the correct settings to make the measurement results valid. Since HP Company of the United States launched the first commercially available semi-automatic spectrum analyzer, the HP8551 Microwave Spectrum Analyzer, in 1964, HP Company has been in a leading position in the field of spectrum analyzers. Marcni and TEK are also manufacturers of high-performance analog spectrum analyzers and have made positive contributions to the development of spectrum analyzers.

In the 1970s, with the successful development of YIG boosters, integrated circuits, high-performance microwave transistors and fixed microwave devices, the development and application of sampling technology, frequency synthesis technology, microwave hybrid integration technology and digital technology, spectrum analyzers They have sprung up like mushrooms and developed rapidly. This achieves wide frequency band, high resolution, high sensitivity and large dynamic range, including multi-state frequency sweep of panoramic display, and absolute value calibration of amplitude and frequency, making it a high-performance and multi-functional measuring instrument. For example, in 1977 HP launched the first microprocessor-based HP8568A radio frequency harmonic analyzer, and in 1978 the HP8566A microwave spectrum analyzer came out.

Since the 1980s, with the development and widespread application of computers and microprocessors, spectrum analyzers have made great strides in the direction of intelligence and automation, and a large number of intelligent spectrum analyzers and automatic spectrum analyzers have appeared. For example, the HP8560E series spectrum analyzer recommended by HP is one of the best laboratory spectrum analyzers currently in use. Optimized for its high performance, the HP8560E series spectrum analyzers can meet the testing needs of various modern applications, such as: RF and microwave communications, military applications, satellite communications, radar, air observation and signal monitoring and EMC/EMI Measurements and more. Using digitally implemented 1IIz full 10z resolution bandwidth filter, I. engineers can significantly improve its resolution and obtain an excellent first-order dynamic range of 109dB. Users can also take advantage of this spectrum analyzer's exceptional phase noise and wide dynamic range spanning 50 GHz full span to measure even low-level signals.

In 1986, HP launched the HP8590A, a flexible and versatile spectrum analyzer that could change their test equipment as needed. Recently, HP8590E series spectrum analyzer engineers have provided a variety of application solutions, such as: RF wireless communications, cable TV, EMT pre-compliance, scanning noise figure, digital radio and broadcast television, etc.

Keysight Technologies N9040B-RT1 Real-Time Analyzer

Since the last century, the popularity of microprocessors and the application of digital technology have promoted the rapid development of spectrum analyzers. Recently, spectrum analyzers have achieved high resolution, large dynamic range, high sensitivity, CRT digital display, and even digital storage and high reliability. Modern computer technology and digital signal processing technology (DSP) are used in spectrum analyzers, which has become the development trend of modern spectrum analyzers. Foreign frequency harmonic analyzer technology is developing rapidly. For example, the American Agilent Company, Tektronix Company, German RS Company, and Japanese ANRITSU Company are constantly launching high-performance spectrum analyzers, and based on the spectrum analyzer, they are constantly expanding their functions. . The future development direction of spectrum analyzers is:

●Develop towards wider frequency band, high sensitivity, high resolution and large dynamic range

Modern spectrum analyzers have wider frequency ranges, higher sensitivity, high resolution, large dynamic range, high measurement accuracy, and faster measurement speeds. They can easily automate the measurement process and miniaturize the instrument. For example, a representative product is the 8565EC spectrum analyzer of the American Agilent Company. Its frequency range is 9kHz~50GHz, the resolution bandwidth is 1Hz~2MHz, the best sensitivity can reach -147dBm, and the noise sideband is -113dBc/Hz (10kHz frequency bias), it also has the functions of extending to higher frequencies, phase noise and digital radio testing, and is very flexible and convenient to use.

●Develop towards broadband, high speed and real-time direction

Real-time spectrum analysis can test signals in real time, and simultaneously conduct panoramic observation, monitoring and analysis of signal indicators in the time domain, frequency domain, modulation domain and code domain. Special signal analysis software can complete complex tasks. The measurement task is the development trend of modern communication analyzers.

The real-time spectrum analyzer can simultaneously obtain the functions of a broadband vector signal analyzer and a spectrum analyzer in one instrument, and has a unique trigger-capture-analysis capability. A typical representative product is the 3086 real-time spectrum analyzer of the American company Tektronix, which can collect the entire spectrum at one time and continuously analyze the full-frame signal. It also has a variety of flexible triggering methods for the analysis of burst signals, transient signals and time-controlled signals. Measure: It is very convenient to measure.