Time-Domain Triggering in Test and Measurement Instruments
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Solution Overview
Problem
Conventional spectrum analyzers lack flexible triggering capabilities for frequency and phase information, particularly in applications involving frequency hopping and phase modulation, leading to false triggers and inadequate data capture due to granular time resolution and limitations in resolving closely spaced frequency components.
Innovation Solution
A test and measurement instrument, such as a Real-Time Spectrum Analyzer, is equipped with an RF input terminal, analog-to-digital converter, digital downconverter, power detector, and demodulators to produce IQ-based time-domain traces, enabling user-definable power threshold comparison and triggering on frequency or phase events, with optional delay to prevent false triggers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional power trigger is used in spectrum analyzer, then triggering is simple to implement, but it cannot trigger on frequency hopping or phase modulation signals where power remains constant
Solution Approach 1:
The patent changes the triggering parameter from power level to frequency and phase information. By monitoring frequency deviations and phase changes instead of power levels, the system can reliably trigger on frequency hopping and phase modulation signals where power remains constant, thus resolving the contradiction between adaptability and reliability.
2Adaptability or versatility
If frequency mask triggering is used, then frequency-based triggering is achieved, but time resolution is too granular and closely spaced frequency components cannot be resolved
Solution Approach 1:
The patent transitions from time-domain frequency mask triggering to frequency-domain spectral analysis. By performing FFT on captured time-domain data and analyzing frequency spectra, the system achieves both flexible frequency-based triggering and high time resolution, as well as the ability to resolve closely spaced frequency components that were impossible with traditional frequency mask methods.
3Quantity of substance
If conventional triggering is used on pulsed RF signals, then all activity including noise is captured, but false triggers occur and rare events are lost in excessive data
Solution Approach 1:
The patent extracts only the relevant frequency and phase information from the captured signal data, separating it from unnecessary noise and irrelevant spectral content. By triggering specifically on frequency deviations and phase changes rather than capturing all signal activity, the system reduces data volume while improving trigger accuracy and enabling the detection of rare events without being overwhelmed by excessive data.
4Reliability
If more acquisition data is stored to capture rare events, then event detection capability improves, but data storage requirements and processing burden increase significantly
Solution Approach 1:
The patent performs preliminary spectral analysis and trigger condition evaluation on captured data before full storage or detailed processing. By using FFT and frequency/phase analysis to identify and trigger on events of interest, the system can detect rare events with minimal data storage requirements, as triggering occurs based on analytical results rather than brute-force examination of all captured data.
Data Source
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AI summary
Embodiments of this invention provide enhanced triggering capabilities such as frequency and phase triggering in a test and measurement instrument, such as a Real-Time Spectrum Analyzer (RTSA) or oscilloscope. A test and measurement instrument can include input terminals to receive RF signals, an ADC to digitize the RF signals, a digital downconverter to produce I and Q baseband component information, and a power detector to determine a power level using the I and Q information. A comparator compares the power level received from the power detector with a user-definable power threshold, and produces a logic signal for enabling one or more phase or frequency demodulators. The one or more demodulators produce IQ-based time-domain traces derived from the I and Q component information when the power level determined by the power detector exceeds the power threshold. Trigger circuitry is configured to trigger on an event responsive to a delayed trigger enable signal.