T&M VSG vs VSA: Understanding Vector Signal Generators and Analyzers
This article explores the differences between Vector Signal Generators (VSG) and Vector Signal Analyzers (VSA), crucial tools in modern wireless communication system testing. The rise of complex modulation schemes like QPSK, 16QAM, and 64QAM, along with multi-antenna and multi-carrier systems (OFDM, OFDMA) in technologies such as Mobile WiMAX, WLAN, LTE, and LTE-Advanced, has made sophisticated waveform analysis essential. This need has driven the development of both vector signal generation and analysis techniques.
Types of Vector Signal Generation and Analysis Tools
There are two main types of VSGs and VSAs:
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Offline Version: This is essentially a software application that generates In-phase and Quadrature (IQ) data. This data is typically in text files, formatted as floating-point, fixed-point, or integer values. This version operates without any radio frequency (RF) components. Offline VSGs and VSAs are particularly useful in the initial stages of development before integrating with RF hardware.
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Online Version: This version combines both baseband and RF components. It produces real-time modulated signals based on the complex vector data dictated by the respective wireless standards.
The following table provides a detailed comparison of VSG and VSA equipment: ""
VSG vs VSA: Key Differences
| Feature | VSG (Vector Signal Generator) | VSA (Vector Signal Analyzer) |
|---|---|---|
| Full Name | Vector Signal Generator | Vector Signal Analyzer |
| Function | Generates complex IQ vectors or modulated IQ vectors at the required RF carrier frequency. | Analyzes complex IQ vectors or modulated IQ vectors at the respective RF carrier frequency. |
| Use Case | Used to test the receiver functionality of a Device Under Test (DUT) with or without RF. | Used to test the transmitter functionality of a Device Under Test (DUT) with or without RF. |
| Hardware Components | Waveform Generator and RF Up Converter. | RF Down Converter and Digitizer. |
| Offline Version Input/Output | Input: Binary data; Output: Complex IQ vector. | Input: Complex IQ vector; Output: Binary data. |
| Typical Measurements | Transmit power, power spectrum, spectral flatness, CCDF, constellation diagram, etc. | Error Vector Magnitude (EVM), channel response, etc. |
Leading Manufacturers of VSGs and VSAs
Here are some of the leading test and measurement companies and their respective models for Vector Signal Generators and Analyzers:
Vector Signal Generators (VSG)
- National Instruments:
- Models: PXI-5670/5671
- Keysight:
- Models: N5182A MXG / M9381A PXIe
- Anritsu:
- Model: MG3710A
- Rohde & Schwarz (R&S):
- Model: SMU200A
Vector Signal Analyzers (VSA)
- National Instruments:
- Models: PXI-5660/5661
- Keysight:
- Model: M9392A PXI with 89600 VSA Software
- Anritsu:
- Models: MT8870A/MS2830A
- Rohde & Schwarz (R&S):
- Model: CMW500
This information provides a solid understanding of the functionalities and key differences between Vector Signal Generators and Vector Signal Analyzers, along with examples of available products from leading manufacturers.
