Parallel Analog and Digital Trigger Paths for Low Latency
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Solution Overview
Problem
The long latency of digital trigger systems in test and measurement instruments, such as oscilloscopes, causes issues when cascaded instruments rely on the trigger out signal, leading to missed events of interest due to increased processing time, especially for events with short capture times.
Innovation Solution
Implementing a low-latency analog trigger processing path in parallel to the standard digital trigger processing path, allowing users to select between digital and analog trigger outputs, with the analog path providing significantly faster trigger signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a digital trigger processing path is used, then processing reliability is improved, but trigger latency increases significantly
Solution Approach 1:
The trigger processing system is segmented into two separate paths: a digital trigger processing path for reliable processing and an analog trigger processing path for low-latency operation. The segmentation allows each path to be optimized for its specific function, resolving the contradiction between reliability and speed by providing both capabilities through dedicated processing channels.
Solution Approach 2:
A trigger selector acts as an intermediary component that chooses between the digital trigger output and the analog trigger output based on the specific application requirements. This mediator enables the system to dynamically switch between reliability-oriented and latency-oriented processing modes, effectively managing the trade-off between these two conflicting parameters.
2Adaptability or versatility
If multiple oscilloscopes are chained together with digital trigger processing, then measurement capability is improved, but cumulative latency causes events to be missed
Solution Approach 1:
By segmenting the trigger processing into separate digital and analog paths, cascaded oscilloscopes can selectively use the analog path for time-critical triggering while maintaining the ability to use digital processing for non-critical applications, thus preserving measurement capability without suffering from cumulative digital latency.
Solution Approach 2:
The system changes the processing parameter (digital vs. analog) based on the specific measurement requirements. For cascaded systems capturing fast events, the parameter shifts to analog processing to minimize latency, while for slower events, digital processing provides sufficient reliability without the need for analog hardware.
3Loss of time
If analog trigger processing is used, then trigger latency is reduced, but processing precision may be compromised
Solution Approach 1:
The segmentation into separate analog and digital paths allows the system to use analog processing only when low latency is critical, while relying on digital processing for applications requiring high precision. This resolves the contradiction by providing both processing modes rather than forcing a compromise in either direction.
Solution Approach 2:
The trigger processing mode becomes dynamic rather than static, allowing the system to adaptively select between analog and digital processing based on real-time requirements. This dynamic selection enables the system to optimize for latency when needed and for precision when needed, eliminating the need to permanently compromise either parameter.
Data Source
AI summary
A test and measurement instrument includes an auxiliary trigger input port for receiving an auxiliary trigger signal, a digital trigger processor for generating a digital trigger signal from the auxiliary trigger signal, an analog trigger processor for generating an analog trigger signal from the auxiliary trigger signal, a user-configurable selector coupled to the digital trigger processor and to the analog trigger processor, the user-configurable selector configured to output either the digital trigger signal or the analog trigger signal as a selected trigger output signal of the instrument. Methods of creating parallel triggers are also described.