Keysight 89600 VSA Application Note: A Deep Dive

This article explores the Keysight 89600 VSA application, a powerful tool for RF signal analysis. We’ll cover what a Vector Signal Analyzer (VSA) is, its key features, and how the 89600 VSA software works.

What is a Vector Signal Analyzer (VSA)?

A Vector Signal Analyzer is an instrument that measures RF signals in the frequency domain, using narrowband detection techniques. While they may not have the pinpoint accuracy of a power meter, their narrowband approach enables them to detect signals down to very low power levels, sometimes as low as -150 dBm.

Think of a VSA as a spectrum analyzer that has been enhanced with sophisticated signal processing capabilities. It doesn’t just measure the signal’s amplitude, but it also breaks the signal down into its in-phase (I) and quadrature (Q) components. This allows VSAs to do much more than traditional spectrum analyzers.

VSAs are indispensable for analyzing modulated signals, such as those generated by mobile phones, wireless LAN devices, and other devices using standards like WiMAX or LTE. They can display complex information, such as constellation diagrams and code domain plots. Plus, they can quantify modulation quality using metrics such as Error Vector Magnitude (EVM).

The Keysight 89600 VSA in Action

The image below shows the Keysight 89600 VSA in action, displaying a constellation diagram, power spectrum, instantaneous power and other relevant information for a complex signal coming from a WiMAX device.

The image illustrates the decoding of a downlink subframe transmitted by a WiMAX base station. You can see key system parameters like FCH, BSID, burst rates and lengths. The software also displays critical measurements like EVM, gain imbalance, and IQ offset.

Key Features of the Keysight 89600 VSA Software

The 89600 VSA software is a versatile tool, offering both offline and real-time analysis capabilities:

• Offline Analysis: The software can be used without any hardware, allowing you to analyze pre-recorded data stored in Keysight-compatible text files.

• Hardware Integration: It’s compatible with over 40 different Keysight hardware models, letting you analyze over-the-air modulated RF signals from devices using WiMAX, LTE, and WLAN technologies.

• Standards Support: The software supports a wide range of cellular standards, including GSM, LTE, LTE-Advanced, and WCDMA.

• IEEE Standards: It also supports IEEE standards like WLAN (802.11n, 802.11ac), WiMAX, Bluetooth, and Zigbee.

• Complex Modulation Analysis: The software can display constellation diagrams for a variety of modulation types, such as AM, PM, FM, BPSK, QPSK, QAM, and OFDM.

• Radar System Analysis: It’s also a useful tool for analyzing radar systems.

How the 89600 VSA Hardware Works

When an RF input signal is fed into the Keysight VSA hardware, it goes through several stages:

1. Signal Conditioning: This involves frequency translation to bring the signal to a usable range.
2. Analog-to-Digital Conversion (ADC): The signal is converted from analog to digital.
3. Quadrature Detection: The signal is separated into its in-phase (I) and quadrature (Q) components.
4. Digital Filtering and Re-sampling: Digital signal processing to remove unwanted components and adapt the sampling rate.
5. Data Windowing: A technique applied to minimize spectral leakage in the FFT process.
6. FFT Analysis or Demodulation: Finally, the signal is either analyzed using Fast Fourier Transform (FFT) or demodulated to extract the information it contains.

In conclusion, the Keysight 89600 VSA is a highly versatile tool for RF signal analysis, offering a range of features that make it suitable for both research and real-world applications. Whether you are analyzing complex modulated signals or working with emerging wireless technologies, the 89600 VSA provides the functionality you need.