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What is a Spectrum Analyzer?

The terms spectrum analyzer and signal analyzer are often used interchangeably, however there are some differences in function and capability. Signal analyzer is a more accurate term for modern day analyzers that provide more comprehensive signal analysis, not only in frequency-domain, but also time and modulation domains.

  • Spectrum analyzer: measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. Its primary use is to measure the power of the spectrum of known and unknown signals.
  • Vector signal analyzer: measures the magnitude and phase of an input signal at a single frequency within the IF bandwidth of the instrument. Its primary use is to make in-channel measurements, such as error vector magnitude, code domain power, and spectral flatness, on known signals.
  • Signal analyzer: performs the functions of a spectrum analyzer and a vector signal analyzer together.


Spectrum Analyzer FAQs

  • Are there different types of spectrum analyzers?
    There are two types of spectrum analyzers and the type is dictated by the method used to obtain the spectrum of a signal. A swept-tuned spectrum analyzer uses a superheterodyne receiver to down-convert a portion of the input signal spectrum (using a voltage-controlled oscillator and a mixer) to the center frequency of a band-pass filter. With a superheterodyne architecture, the voltage-controlled oscillator is swept through a range of frequencies, enabling the consideration of the full frequency range of the instrument. A fast Fourier transformation (FFT) analyzer computes the discrete Fourier transform (DFT), a mathematical process that transforms a waveform into the components of its frequency spectrum, of the input signal.
  • When would I use a benchtop rather than a handheld spectrum analyzer?
    Benchtop spectrum and signal analyzers offer superior specifications and measurement applications, while handheld spectrum analyzers are favored by those who spend more of their time in the field.
  • Can a spectrum analyzer produce real-time results?
    Yes, a real-time spectrum analyzer uses a hybrid technique where the incoming signal is first down-converted to a lower frequency using superheterodyne techniques and then it is analyzed using FFT techniques.  Keysight offers a real-time option for the PXA signal analyzer.
  • Can I demodulate signals with a spectrum analyzer?
    By using a spectrum or signal analyzer with Keysight’s 89600 VSA flexible modulation analysis software or measurement applications, you can demodulate a broad range of standard-based and general-purpose digital signals and formats.
  • What types of spectrum analyzers does Keysight offer?
    Keysight offers a broad range of signal analyzer products, including swept-tuned and FFT spectrum analyzers, spectrum analyzer software and spectrum analyzer measurement applications.
  • What frequency range does Keysight’s spectrum analyzer offering cover?
    Keysight offers an extensive selection of spectrum and signal analyzer products from DC to 50 GHz and extendable to 325 GHz with external mixers.