Frequency Mask Trigger Amplitude Discrimination
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Solution Overview
Problem
Conventional frequency mask triggers cannot detect RF signals with selected frequency components that fail to reach a desired power level due to the lack of amplitude range qualification, distinguishing between signals that are too low in amplitude and those that are not present at all.
Innovation Solution
A frequency mask trigger with frequency selective amplitude discrimination capability is implemented, where a frame of digital data representing an RF signal is transformed into a frequency spectrum, and power amplitude values are compared to upper and lower reference power levels to generate a trigger signal only when the signal remains within these specified levels for a specified time duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional frequency mask trigger is used, then the trigger can detect presence of frequency components, but it cannot distinguish between signals that are present but too low in amplitude from those that are not present at all
Solution Approach 1:
The trigger functionality is segmented into multiple independent comparison operations: one comparator checks if the signal exceeds a lower threshold, another checks if it falls below an upper threshold. This segmentation allows the system to detect amplitude violations without requiring a single complex comparison circuit, thereby improving measurement precision while controlling device complexity.
Solution Approach 2:
The invention transitions from single-threshold detection to dual-threshold detection, adding an amplitude dimension to the frequency-based triggering. By introducing both upper and lower reference power levels, the system creates a two-dimensional amplitude discrimination capability that distinguishes between absent signals and present-but-too-weak signals, resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If the frequency mask trigger waits for a single specific spectral event, then it can trigger on frequency presence, but it cannot qualify the trigger signal based on amplitude range
Solution Approach 1:
The system performs preliminary amplitude checks by comparing the signal against both upper and lower reference power levels before generating a trigger. This preliminary action of establishing amplitude boundaries in advance allows the trigger to qualify signals based on amplitude range without adding complex real-time decision logic, thereby improving measurement precision while keeping trigger logic complexity manageable.
3Reliability
If no amplitude discrimination is provided, then the trigger response is simple, but false triggers occur when signals are present but below desired power level
Solution Approach 1:
Reference power levels serve as intermediary values that mediate between the raw signal and the trigger decision. By introducing upper and lower reference power levels as intermediate comparison points, the system achieves reliable trigger accuracy that distinguishes between acceptable and unacceptable signal amplitudes, while the comparison circuit complexity remains manageable through the use of standard comparator components.
Data Source
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AI summary
A frequency mask trigger having frequency selective amplitude discrimination capability is provided for triggering when selected frequency components of an input signal fail to reach a desired power level. A frame of digital data representing an input signal is transformed (46) into a frequency spectrum having at least one frequency bin, each frequency bin having a power amplitude value. Each power amplitude value is compared to an upper reference power level (52) and a lower reference power level (48). A trigger signal is generated when the power amplitude value in any frequency bin is above the lower reference power level and below the upper reference power level for a specified time duration (56).