Automatic Frequency Prescaler With Adaptive Divide Ratio Selection
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Solution Overview
Problem
Traditional frequency counters require manual signal transfer between ports when frequency changes, leading to increased jitter and impracticality with high-speed complex signals, and are limited by a single conditioning circuit that over-adjusts low-frequency signals.
Innovation Solution
An oscilloscope configured with multiple circuit dividers and a control system that iteratively determines the signal frequency and selects an optimal divide ratio, reducing jitter by continuously retesting and adjusting the signal path, and employing frequency hysteresis to minimize chatter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single conditioning circuit is used to accommodate the highest frequency signal, then the device can handle high frequency signals, but low frequency signals are over adjusted resulting in increased jitter
Solution Approach 1:
The single conditioning circuit is segmented into multiple conditioning circuits, each optimized for specific frequency ranges. This allows low frequency signals to be processed by circuits designed for their range rather than being over-adjusted by high-frequency optimized circuits, reducing jitter while maintaining broad frequency coverage
Solution Approach 2:
The system dynamically selects which conditioning circuit to use based on the detected frequency of the input signal. This dynamic adaptation ensures that the appropriate circuit is always active, preventing over-adjustment of low frequency signals while maintaining capability across the full frequency spectrum
2Measurement precision
If manual transfer between ports is required for frequency band changes, then separate optimized ports can be used, but this is impractical for high speed complex signals that rapidly change frequencies
Solution Approach 1:
The frequency counter system performs self-service by automatically detecting the input signal frequency and routing it to the appropriate conditioning circuit without requiring manual user intervention. This eliminates the impracticality of manual port switching for high-speed complex signals while maintaining optimized signal conditioning
Solution Approach 2:
The system uses feedback from frequency detection to automatically control the routing of input signals to appropriate conditioning circuits. This closed-loop approach ensures optimal signal processing is maintained without user involvement, handling rapid frequency changes effectively
3Measurement precision
If multiple hardware circuits are used for different frequency bands, then each circuit can be optimized for its range, but the device complexity increases
Solution Approach 1:
Multiple conditioning circuits are designed with universal functionality to handle different frequency ranges, each circuit capable of adapting to various signal types. This reduces overall system complexity compared to dedicated circuits for each frequency band while maintaining frequency-specific optimization through software-controlled selection
Data Source
AI summary
A test and measurement instrument including an input port configured to receive an input signal. One or more divider circuits, coupled to the input port, employ a plurality of divide ratios such that each divide ratio scales an event signal indicating events in the input signal by a predetermined integer value. A control system is also included. The control system is configured to iteratively determine an estimated signal frequency of the event signal, and automatically select a divide ratio for the event signal based on the estimated signal frequency. The instrument may also include one or more counters to count triggers in the event signal subsequent to application of the divide ratio. The instrument may also employ frequency hysteresis to prevent chatter in divide ratio selection.