Automatic Frequency Prescaler With Adaptive Divide Ratio Switching
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Solution Overview
Problem
Traditional frequency counters require manual signal transfer between ports when frequency changes, leading to increased jitter and are not suitable for high-speed complex signals, as they employ a single conditioning circuit locked to a maximum value, causing over-adjustment of low-frequency signals and are not amenable to trigger level-based conditioning.
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, continuously retesting and swapping the signal to minimize jitter, and employs a frequency hysteresis process to reduce chatter by requiring a predetermined margin for divide ratio changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single conditioning circuit is locked to a maximum conditioning value to accommodate the highest frequency signal, then the highest frequency signal can be measured, but low frequency signals are over adjusted resulting in increased jitter
Solution Approach 1:
The patent divides the single conditioning circuit into multiple conditioning circuits, each with different conditioning values optimized for specific frequency ranges. This segmentation allows low frequency signals to be processed by circuits with appropriate conditioning values rather than being over-adjusted by a maximum-value circuit, thereby reducing jitter while maintaining the ability to measure high frequency signals.
Solution Approach 2:
The patent implements dynamic switching between multiple conditioning circuits based on the detected frequency range of the input signal. The system automatically selects the appropriate conditioning circuit for the current signal frequency, making the conditioning configuration adaptive rather than fixed. This dynamic approach ensures optimal conditioning for each frequency range without the jitter issues associated with static maximum-value conditioning.
2Adaptability or versatility
If manual transfer of input signal between ports is required when frequency changes, then different frequency bands can be measured, but the process is impractical for high speed complex signals that rapidly change frequencies
Solution Approach 1:
The patent implements an automatic frequency detection and routing system that self-adjusts the signal path based on the input signal's frequency characteristics. The system automatically detects the frequency range and routes the signal to the appropriate measurement circuit without requiring manual user intervention. This self-service mechanism makes the system practical for high-speed complex signals that rapidly change frequencies, as the automatic routing keeps pace with the signal variations.
Solution Approach 2:
The patent creates a dynamic signal routing system that automatically adapts to changing signal frequencies in real-time. Multiple input ports and conditioning circuits are dynamically selected based on the current signal characteristics, allowing the system to handle rapidly changing high-speed signals without manual reconfiguration. This dynamic adaptability maintains both frequency band coverage and operational ease.
3Adaptability or versatility
If multiple hardware circuits are used for analyzing a broad range of input signals, then different frequency signals can be measured, but the device complexity increases
Solution Approach 1:
The patent designs multiple conditioning circuits and input ports to share common measurement and control resources. Rather than having completely separate measurement systems for different frequency ranges, the system uses a unified measurement circuit that can process signals from multiple conditioning paths. This multi-functionality approach reduces overall device complexity while maintaining the capability to measure a broad range of input signal frequencies.
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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.