Phase Coherent Waveform Playback in Arbitrary Waveform Generators
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Solution Overview
Problem
Current arbitrary waveform generators (AWGs) fail to achieve phase coherent playback when switching between stored waveforms, as they typically start from the beginning of each new waveform, disrupting the phase synchronization necessary for simulating continuous signals like wireless communication signals.
Innovation Solution
The AWG incorporates a sequencer with a waveform starting position indicator and a mechanism to track the phase of previously output waveforms, using a clock generator and counter to maintain the conceptual sample position, allowing seamless phase-coherent playback by starting at an offset position within the waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the waveform playout system starts from the beginning of each new waveform when switching, then the waveform switching is simple and straightforward, but phase coherence is lost and the signal appears discontinuous
Solution Approach 1:
The system performs preliminary actions by tracking the phase position of waveforms before switching occurs. The phase tracker continuously monitors and records the phase state of each waveform in advance, so when a switch is needed, the system can immediately resume from the correct phase position rather than restarting from the beginning, thus maintaining phase coherence without complex real-time adjustments
Solution Approach 2:
The patent implements a feedback mechanism where the phase tracker continuously monitors the phase position of played waveforms and feeds this information back to the waveform selection and playback control. This feedback loop ensures that when switching between waveforms, the system knows exactly where each waveform left off and can resume playback at the correct phase position, maintaining continuous phase coherence across waveform transitions
2Adaptability or versatility
If the AWG switches between stored waveforms using traditional methods, then the operation is simple, but the ability to simulate continuous signals like wireless communication signals is compromised
Solution Approach 1:
The patent introduces a phase tracker as an intermediary component between the waveform memory and the D/A converter. This phase tracker mediates the waveform switching process by tracking and recording phase information, allowing the system to switch between waveforms while maintaining phase coherence. The intermediary handles the complexity of phase management, enabling simple waveform switching operations that preserve signal continuity for realistic communication signal simulation
3Reliability
If the waveform playout system always starts from the first sample of each waveform, then the playback control is straightforward, but phase discontinuity occurs during waveform switching
Solution Approach 1:
The system performs preliminary phase tracking and position recording before waveform switching occurs. The phase tracker continuously monitors and stores the phase position of each waveform in advance, enabling the playback system to resume from the correct position rather than always starting from the first sample. This preliminary action maintains phase continuity while keeping the playback control mechanism relatively simple
Solution Approach 2:
The patent implements a feedback mechanism where phase position information is continuously monitored and fed back to control waveform playback. This feedback loop ensures that when switching between waveforms, the system knows exactly where each waveform left off and can resume playback at the correct phase position, maintaining continuous phase coherence across waveform transitions without complex real-time adjustments
Data Source
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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.