Waveform Synthesizer Jitter Insertion for Real-Time Signal Testing
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Solution Overview
Problem
Conventional test and measurement instruments lack the necessary baud rate range and flexible impairment generation capabilities to effectively simulate various communication standards' jitter requirements for stress testing devices under test (DUTs).
Innovation Solution
The implementation of digital signal processing (DSP) or analog methods to modulate the signal source DAC sample clock in real-time, adding impairments like jitter and spread spectrum clocking to data waveforms, using FPGA or ASICs, or pre-computation with waveform pattern memory, to generate waveforms with desired impairments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional test and measurement instruments are used, then device simplicity is maintained, but baud rate range and impairment generation capabilities are insufficient
Solution Approach 1:
The patent combines the signal source and impairment generation functions into a single integrated instrument. The arbitrary waveform generator is merged with impairment generation capabilities, allowing multiple functions (signal generation, jitter insertion, ISI simulation) to be performed by one device rather than requiring separate instruments.
Solution Approach 2:
The instrument is designed to support multiple communication standards and impairment types through a universal architecture. The arbitrary waveform generator can generate different waveform types (PAM4, NRZ, etc.) and insert various impairments (jitter, ISI, noise) using a common signal processing path, making the device adaptable to diverse testing requirements.
2Measurement precision
If real-time DSP or analog modulation methods are used, then accurate jitter simulation is achieved, but processing complexity increases
Solution Approach 1:
The patent replaces traditional mechanical or analog jitter insertion methods with digital signal processing. Instead of using physical modulation hardware, the system uses DSP algorithms to generate and insert jitter impairments digitally, achieving high precision while reducing mechanical complexity.
Solution Approach 2:
The system changes the approach from fixed analog jitter parameters to dynamically adjustable digital parameters. The jitter characteristics (magnitude, frequency, type) are controlled through software-configurable parameters, allowing precise control and easy adjustment without hardware reconfiguration.
3Productivity
If pre-computation with waveform pattern memory is used, then real-time generation capability is improved, but memory requirements increase
Solution Approach 1:
The patent uses pre-computed waveform patterns stored in memory to enable fast real-time generation. Complex waveforms and impairment patterns are calculated in advance and stored, allowing the instrument to rapidly reproduce them during testing without performing complex calculations in real-time.
Solution Approach 2:
The system creates digital copies of waveform patterns and impairment sequences in memory. Instead of generating waveforms from scratch during each test, the pre-computed patterns are copied and reproduced, significantly speeding up the test execution while requiring memory storage for the pattern copies.
Data Source
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AI summary
A test and measurement device having a signal source, including an impairment generator configured to output an impairment and a waveform synthesizer. The waveform synthesizer receives an input digital signal to be synthesized, receives the impairment, and synthesizes a synthesized digital signal based on the input digital signal and the impairment. The test and measurement instrument also includes a fixed sample rate digital-to-analog converter configured to receive a clock signal and the synthesized digital signal and output an analog signal.