Tutorial-7: Vector Modulation Analysis

Summary

This tutorial demonstrates how to perform vector modulation analysis in SystemVue. It builds on the previous QPSK modulator tutorial and introduces the Digital D Mod tool for real-time demodulation analysis. Key features such as symbol rate settings, modulation formats, and receiver criteria are explored, allowing users to assess modulator performance. The video also explains how to visualize results like EVM and IQ offset, while illustrating how to save and plot data. The tutorial concludes by showing how to add imperfections like gain imbalance and phase distortion, emphasizing the accuracy of SystemVue’s analysis engine.

Takeaways

• 😀 The tutorial covers vector modulation analysis using SystemVue's Digital Demodulator tool.
• 😀 In Tutorial 6, a QPSK modulator was designed, and this tutorial focuses on evaluating its performance.
• 😀 The Digital Demodulator allows for real-time analysis of modulation quality, including key metrics like EVM and IQ offset.
• 😀 Key parameters for the Digital Demodulator include symbol rate, symbol length, modulation type, and reference receiver settings.
• 😀 The reference receiver settings include setting the measurement filter to root raised cosine and adjusting the roll-off factor to 0.35.
• 😀 The Continuous Mode setting ensures the analysis keeps running, displaying real-time results such as constellation diagrams and EVM.
• 😀 Simulation results show EVM (RMS) and IQ offset values that help evaluate the modulator's ideal performance.
• 😀 If real-time monitoring is not needed, Continuous Mode can be turned off, and simulation results can be saved for later analysis.
• 😀 Results like EVM can be plotted in tables for further analysis and comparison in the schematic.
• 😀 Distortions like gain imbalance and phase imbalance can be introduced to simulate imperfect designs and observe their effects on EVM and other metrics.
• 😀 SystemVue's built-in tools allow accurate analysis of modulation performance without requiring external software for quality checks.

Q & A

What is the main focus of this tutorial?

The tutorial focuses on performing vector modulation analysis in SystemVue, specifically checking the performance of a QPSK modulator.

Why is vector modulation analysis important in SystemVue?

Vector modulation analysis is essential to evaluate the quality and performance of a modulator, beyond just observing the spectrum.

What tool in SystemVue is used for vector modulation analysis?

The 'Digital D Mod' tool, located under the Syncs category in the Algorithm Design section, is used for vector modulation analysis.

What parameters can be defined in the 'Digital D Mod' settings?

In the 'Digital D Mod' settings, you can define the symbol rate, result length (number of symbols to average), modulation type (e.g., BPSK, QPSK), and reference receiver criteria.

What does the constellation diagram represent in this analysis?

The constellation diagram shows the received symbols in the IQ plane, helping to visually assess the quality of the modulation scheme.

What performance metrics are shown in the analysis results?

The performance metrics include EVM (Error Vector Magnitude), IQ offset, and other related parameters such as magnitude error per symbol.

What is the significance of the EVM value?

The EVM value indicates the accuracy of the received signal compared to the ideal signal. A lower EVM value generally signifies better modulator performance.

How can results be stored or displayed for later review?

Results can be stored in a data set and displayed in a table. You can plot parameters like EVM RMS by right-clicking and adding them to a table for easy viewing and analysis.

What happens when 'continuous mode' is enabled during simulation?

When 'continuous mode' is enabled, the measurement keeps running continuously, providing real-time updates unless the simulation is manually stopped.

How can you simulate imperfections in the modulator design?

You can simulate imperfections by introducing impairments such as gain imbalance or phase imbalance in the modulator. This allows for testing the system's performance under non-ideal conditions.