Editing Vector signal analyzer (section)

===Down-convert and digitize stage===
A vector signal analyzer operates by first down-converting the signal spectra by using [[superheterodyne receiver|superheterodyne techniques]].
A portion of the input signal spectrum is [[Superheterodyne receiver#High-side and low-side injection|down-converted]] (using a [[voltage-controlled oscillator]] and a [[Frequency mixer|mixer]]) to the center frequency of a [[band-pass filter]]. The use of a [[voltage-controlled oscillator]] allows consideration of different carrier frequencies.

After the conversion to an [[intermediate frequency]], the signal is [[electronic filter|filtered]] in order to band-limit the signal and prevent [[aliasing]]. The signal is then [[digitizing|digitized]] using an [[analog-to-digital converter]]. [[Sampling rate]] is often varied in relation to the frequency span under consideration.