Vector Signal Analyzer
Understanding VSAs
The VSA is the essential instrument for verifying digital signal quality. As modulation schemes become more complex (256-QAM, 1024-QAM), the ability to measure signal quality beyond simple power and spectrum is critical.
VSA Capabilities
- EVM measurement: Quantifies modulation quality. Required for 5G: < 3-8% depending on modulation order.
- Constellation diagram: Visual representation of IQ symbols. Shows compression, phase noise, IQ imbalance.
- Spectral emission: ACLR, SEM (Spectral Emission Mask) compliance testing.
- Code-domain analysis: Power per code for CDMA/WCDMA. Per-subcarrier analysis for OFDM.
Frequently Asked Questions
What is a VSA?
A VSA captures amplitude and phase of RF signals for modulation analysis. It measures EVM, displays constellation diagrams, and performs spectral emission testing. Essential for 5G, Wi-Fi, and satellite signal quality verification.
VSA vs spectrum analyzer?
Spectrum analyzer: amplitude vs frequency only. VSA: amplitude AND phase, enabling IQ demodulation, EVM, and constellation analysis. For modern digital signals, a VSA is essential. Many high-end spectrum analyzers include VSA capabilities.
What VSA bandwidth is needed for 5G?
5G NR FR1: 100 MHz component carrier bandwidth. FR2 (mmWave): 400 MHz. Including DPD observation: 3-5x = 300 MHz to 2 GHz analysis bandwidth. Modern VSAs offer 1-2 GHz instantaneous bandwidth.