Arbitrary Waveform Generator Playback for Phase-Coherent Switching
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Solution Overview
Problem
Arbitrary waveform generators (AWGs) currently lack phase coherence when switching between stored waveforms, which is essential for simulating continuous signals in test environments, such as wireless communication signals, where phase synchronization is critical.
Innovation Solution
The AWG is modified to include a waveform starting position indication and a mechanism for tracking the phase of previously output waveforms, using a clock generator, counter, and modulus to ensure phase coherence by starting playback at a specific sample position within the waveform, rather than from the beginning, and utilizing an offset signal to maintain the conceptual sample position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the waveform playout system starts playback from the beginning of each new waveform, then the waveform switching is simple and straightforward, but phase coherence is lost when switching between waveforms
Solution Approach 1:
The system pre-calculates and stores the starting position information for each waveform in advance. When a waveform needs to be replayed, the pre-stored starting position is retrieved and applied, eliminating the need for complex real-time phase calculation while maintaining phase coherence.
Solution Approach 2:
A waveform starting position indicator is introduced as an intermediary element between the sequencer and the waveform playout system. This indicator carries the necessary phase information without requiring the sequencer to directly control the playout timing, simplifying the overall control architecture.
2Measurement precision
If the sequencer provides detailed control over waveform playback timing, then precise event alignment is achieved, but tracking the conceptual sample position becomes complex
Solution Approach 1:
The waveform playout system automatically tracks its own conceptual sample position and generates the appropriate starting position indicators without external intervention. This self-service mechanism eliminates the need for complex external tracking systems while maintaining precise event alignment.
Solution Approach 2:
Instead of directly tracking the continuous conceptual sample position, the system creates discrete copies of position information at specific event points. These position copies are stored and reused when waveforms need to be replayed, simplifying the tracking mechanism while preserving precision.
Data Source
AI summary
An improved arbitrary waveform generator has a waveform memory for storing digitized waveforms, a waveform playout for playing out desired ones of the digitized waveforms as analog waveforms and a sequencer for controlling the waveform playout, the sequencer providing indications of the desired waveform for playout and a desired starting sample position for the desired waveform. The sequencer includes a tracking mechanism for the desired waveform so that the desired waveform is phase coherent when playout is interrupted and restarted later according to programming of the sequencer.