Real-time Spectrum Analyzer Frequency Mask Gate
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Solution Overview
Problem
Conventional real-time spectrum analyzers experience gaps in continuous visual displays due to the display of all FFTs in a slice, even if only one meets the trigger condition, which is problematic for input signals moving in and out of the trigger condition within a single slice, and is not compatible with gap-free density histograms.
Innovation Solution
A real-time spectrum analyzer with a frequency mask gate that selectively outputs only FFT spectra containing at least one point meeting the trigger condition, using gate control signals to gate the FFT spectra and store only relevant data for a continuous gap-free display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If all FFTs in a histogram slice are displayed regardless of trigger condition, then complete data coverage is achieved, but display accuracy and relevance deteriorate due to inclusion of irrelevant spectra
Solution Approach 1:
The patent extracts only the relevant FFT spectra that meet the trigger condition from the complete set of FFT spectra. The frequency mask gate selectively passes only those spectra containing at least one FFT point that satisfies the trigger condition, discarding irrelevant spectra. This extraction principle resolves the contradiction by maintaining data coverage for relevant signals while eliminating irrelevant data that reduces display accuracy.
Solution Approach 2:
The patent applies different quality criteria to different portions of the data stream. Instead of uniformly displaying all spectra or none, it applies a local quality filter (frequency mask trigger condition) to each individual FFT spectrum. Each spectrum is evaluated independently based on whether it contains relevant information, allowing high-quality relevant spectra to be displayed while filtering out low-quality irrelevant spectra.
2Reliability
If conventional frequency mask trigger is used, then triggered measurements are provided, but real-time gap free operation is lost during data transfer and display processes
Solution Approach 1:
The patent performs preliminary evaluation of each FFT spectrum against the trigger condition using the frequency mask detector before the spectrum reaches the display stage. The frequency mask gate makes gating decisions based on this preliminary evaluation, determining in advance which spectra should be displayed. This preliminary action ensures that only relevant spectra are transferred to display memory, maintaining continuous real-time operation without gaps while still providing reliable triggered measurements.
Solution Approach 2:
The frequency mask gate acts as an intermediary component between the FFT engine and the display system. It receives all FFT spectra from the FFT engine and selectively passes only those meeting the trigger condition to the display memory. This intermediary function resolves the contradiction by enabling triggered measurement capability while maintaining continuous real-time operation, as the gate operates continuously without stopping the data flow.
3Area of stationary object
If all FFT spectra are displayed in a slice, then comprehensive visualization is achieved, but display efficiency and relevance worsen due to inclusion of unnecessary data
Solution Approach 1:
The patent extracts only the necessary FFT spectra for display by using the frequency mask gate to filter out irrelevant spectra. Instead of displaying the complete set of FFT spectra that would occupy full display area, it extracts and displays only those spectra containing at least one FFT point meeting the trigger condition. This maintains effective display coverage with relevant information while improving display efficiency by reducing the amount of data processing and memory requirements.
Data Source
AI summary
A real-time spectrum analyzer for measuring time domain data sampled from an input signal includes a processing unit and a density histogram memory unit. The processing unit includes an FFT engine, a frequency mask detector and a frequency mask gate. The FFT engine performs FFTs on the sampled time domain data to provide FFT spectra, each FFT spectrum including multiple FFT points. The frequency mask detector determines whether each FFT point in each spectrum meets a trigger condition, and generates gate control signals corresponding to the FFT spectra based on the determinations. The frequency mask gate receives the FFT spectra and the gate control signals, and outputs only select FFT spectra that contain at least one FFT point that meets the trigger condition in response to the corresponding gate control signal. The density histogram memory unit stores the select FFT spectra for generating in a density histogram.