IQ Time-Domain Triggering for Frequency and Phase Event Capture
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Solution Overview
Problem
Conventional spectrum analyzers lack flexible triggering capabilities, particularly for frequency hopping and phase modulation applications, leading to inefficient data acquisition and false triggering issues due to granular time resolution and inability to isolate specific frequency or phase events.
Innovation Solution
A test and measurement instrument with enhanced triggering capabilities, including frequency and phase triggering, utilizing an RF/IF converter, analog-to-digital converter, digital downconverter, power detector, and trigger circuitry to produce IQ-based time-domain traces and enable demodulators only when a predefined power threshold is exceeded, allowing for user-definable triggering on specific events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency mask triggering approach is used, then frequency-based triggering is achieved, but time resolution becomes too granular and closely spaced frequency components cannot be resolved
Solution Approach 1:
The patent transitions from frequency-domain triggering (frequency mask) to time-domain triggering by producing IQ-based time-domain traces. This dimensional change allows the system to resolve events in the time domain with fine granularity while maintaining frequency analysis capabilities through the IQ trace representation, thereby resolving the contradiction between frequency resolution and time resolution.
Solution Approach 2:
The patent introduces IQ-based time-domain traces as an intermediary representation between the RF signal and the triggering mechanism. These traces serve as a mediator that provides high-time-resolution event detection while preserving frequency information, allowing the system to achieve both fine time resolution and accurate frequency measurement without the limitations of conventional frequency mask triggering.
2Ease of operation
If traditional power trigger is used, then simple triggering is achieved, but it becomes useless for frequency hopping applications where power remains constant
Solution Approach 1:
The patent changes the triggering parameter from power level (which remains constant in frequency hopping) to frequency and phase parameters extracted from IQ traces. This parameter transformation enables the trigger to detect frequency hops and phase changes while maintaining the simplicity of the triggering mechanism, as the system still uses threshold-based triggering on the transformed parameters rather than complex signal processing.
Solution Approach 2:
The patent makes the triggering system dynamic by continuously updating the IQ-based time-domain traces and frequency/phase measurements in real-time. This dynamic approach allows the trigger to adapt to frequency hopping and phase modulation patterns, providing versatile triggering capability for modern communication signals while maintaining ease of operation through automated parameter extraction and comparison.
3Productivity
If conventional triggering is used for rare events, then data acquisition is performed, but false triggering occurs and rare events cannot be reliably captured
Solution Approach 1:
The patent performs preliminary action by continuously acquiring and storing IQ-based time-domain traces and frequency/phase information in real-time, even before the rare event occurs. This preliminary data accumulation allows the system to reliably detect and trigger on rare events when they occur, while the continuous acquisition ensures that sufficient data is available for analysis. The preliminary action of continuous monitoring at high resolution prevents false triggering by establishing a baseline of normal signal behavior.
Solution Approach 2:
The patent replaces conventional mechanical triggering mechanisms with a digital signal processing-based system that uses IQ traces and frequency/phase analysis. This substitution eliminates false triggering caused by noise and signal artifacts, as the digital processing can distinguish between genuine rare events and false signals. The electronic/digital mechanism provides both high reliability for rare event detection and sufficient data acquisition rate through continuous digital monitoring.
Data Source
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.