Vector Signal Analysis Basics
应用文章
This application note serves as a primer on the vector signal analyzer (VSA). This chapter discusses VSA measurement concepts and theory of operation; Chapter 2 discusses VSA vector-modulation analysis and, specifically, digital-modulation analysis.
Analog, swept-tuned spectrum analyzers use superheterodyne technology to cover wide frequency ranges; from audio, through microwave, to millimeter frequencies. Fast Fourier transform (FFT) analyzers use digital signal processing (DSP) to provide high-resolution spectrum and network analysis, but are limited to low frequencies due to the limits of analog-to-digital conversion (ADC) and signal processing technologies. Today’s widebandwidth, vector-modulated (also called complex or digitally modulated), time-varying signals benefit greatly from the capabilities of FFT analysis and other DSP techniques. VSAs combine superheterodyne technology with high speed ADCs and other DSP technologies to offer fast, high-resolution spectrum measurements, demodulation, and advanced time-domain analysis. A VSA is especially useful for characterizing complex signals such as burst, transient, or modulated signals used in communications, video, broadcast, sonar, and ultrasound imaging applications.