Editing Vector signal analyzer (section)

[[File:VSA screenshot.PNG|right|400px|thumb|A vector signal analyzer display featuring a constellation diagram, demodulation error data, signal spectrum, and the real-time measured signal]]
A '''vector signal analyzer''' is an instrument that measures the magnitude and phase of the input signal at a single frequency within the [[Intermediate frequency|IF]] [[Bandwidth (signal processing)|bandwidth]] of the instrument. The primary use is to make in-channel measurements, such as [[error vector magnitude]], code domain power, and [[spectral flatness]], on known signals.

Vector signal analyzers are useful in measuring and [[Demodulation|demodulating]] [[Modulation#Digital modulation methods|digitally modulated signals]] like [[W-CDMA (UMTS)|W-CDMA]], [[3GPP Long Term Evolution|LTE]], and [[Wireless LAN|WLAN]].<ref>National Institute of Standards and Technology [http://www.eeel.nist.gov/kate_papers/R13_NIST_TN1546_Modulated_Signal_(Web)1.pdf], ''Measurement to Support Modulated-Signal Radio Transmissions for the Public-Safety Sector'', p. 15, April, 2008, accessed July 19, 2011.</ref> These measurements are used to determine the quality of [[modulation]] and can be used for design validation and compliance testing of electronic devices.