spectrum analyzer

spectrum analyzer

[′spek·trəm ′an·ə‚līz·ər]

(engineering)

Test instrument used to show the distribution of energy contained in the frequencies emitted by a pulse magnetron; also used to measure the Q of resonant cavities and lines, and to measure the cold impedance of a magnetron.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

spectrum analyzer

A hardware device or software used to examine the frequency and power components of a signal. It provides more information than an oscilloscope, because it can display the signals over a range of frequencies. For example, whereas an oscilloscope would show total noise level, a spectrum analyzer would show the noise as related to frequency. Available in both analog and digital models, digital analyzers sample the incoming waveforms and convert them to fast fourier transforms (FFTs).

Bandwidth Resolution
The range of frequencies being analyzed is the "bandwidth," while the width of the individual samples is the "bandwidth resolution." In the following example, the bandwidth is 86 Hz to 20 kHz, and the bandwidth resolution is 40 Hz. Each sample represents a 40 Hz section of the displayed 19,914 Hz band. See oscilloscope.

An Audio Analysis

This example shows the power levels and frequencies of an audio signal as displayed in a software-based spectrum analyzer.

Copyright © 1981-2025 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Spectrum Analyzer

 

a laboratory measuring instrument used for studying the frequency spectra observed on the screen of an electron-ray tube as well as the pulse- and amplitude-modulated oscillations in 3– and 10–cm wave bands. In order to obtain oscillographic patterns of the spectra of the oscillations under investigation in “power-frequency” coordinates, a superheterodyne radio receiver is used in the spectrum analyzer. In this receiver the incoming oscillations are weakened (if necessary) by attenuators, transformed according to frequency, and strengthened; then they enter on the vertically deflected plate of the electron-ray tube. The frequency of the receiver’s oscillator varies linearly by ±8 mHz (in a 10–cm band) or ±30 mHz (in a 3–cm band) in step with the saw-toothed tension sweep, which is simultaneously fed into the loops that change the heterodyne’s frequency and on the horizontal plates of the electron-ray tube. Frequency calibration is provided for in the analyzer by an oscillator with calibrated markers, having smooth control of amplitude and frequency ranging from 1 to 10 mHz. The spectrum analyzer can measure the oscillator’s frequency drift, minor differences in the frequency of two oscillators, and so forth.

REFERENCE

Shkurin, G. P. Spravochnik po elektroizmeritel’nym i radioizmeritel’nym priboram, 3rd ed., vol. 2. Moscow, 1960.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.