FFT Spectrum Analyzer Video Bandwidth Emulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
FFT-based spectrum analyzers cannot replicate the video bandwidth settings of swept spectrum analyzers due to the absence of a video filter, leading to incompatibility in measurement conditions.
Innovation Solution
The signal analyzer processes FFT-calculated spectrum data by establishing a linear relationship between frequency and time changes, allowing for the application of video filter characteristics, which enables the emulation of a swept spectrum analyzer's video filter functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FFT calculation is used in spectrum analyzer, then processing speed and productivity are improved, but the ability to apply video bandwidth settings and measurement compatibility with swept spectrum analyzers deteriorates
Solution Approach 1:
The patent applies a digital filter to FFT-calculated spectrum data to replicate the noise reduction effect of an analog video filter in swept spectrum analyzers. By copying the filter characteristics and applying them digitally to the spectrum data, the system maintains measurement compatibility while using faster FFT processing, thus resolving the contradiction between processing speed and measurement compatibility
Solution Approach 2:
The patent replaces the mechanical/analog video filter system with a digital filtering approach. Instead of using an analog video filter after the IF filter, the system applies digital filtering to the FFT-calculated spectrum data, substituting the analog mechanism with a digital processing equivalent that achieves the same noise reduction effect while maintaining compatibility
2Object-affected harmful factors
If video filter is applied to reduce noise in swept spectrum analyzer, then noise reduction effectiveness is improved, but device complexity increases due to additional filter components
Solution Approach 1:
The patent extracts the essential function of the video filter (noise reduction through bandwidth limiting) and applies it digitally to the spectrum data. By separating the noise reduction function from the physical analog filter hardware and implementing it through digital signal processing, the system achieves noise reduction without adding complex analog filter components
Solution Approach 2:
The patent substitutes the analog video filter mechanism with a digital filtering approach. The digital filter is applied to FFT-calculated spectrum data to achieve the same noise reduction effect as an analog video filter would provide in a swept spectrum analyzer, eliminating the need for additional analog filter hardware while maintaining noise reduction effectiveness
Data Source
AI summary
A data processing method is provided to enable a calculation based signal analyzer, such as an FFT based spectrum analyzer, to produce results corresponding to a swept spectrum analyzer employing a video bandwidth (VBW) filter. Once a spectrum is produced the frequency axis is replace by a corresponding time axis, so that a time domain filter, such as a video bandwidth (VBW) filter can be applied. The filter characteristics are applied by performing an FFT to produce frequency domain data, multiplying by the frequency response to produce a filtered version, performing an inverse FFT and replacing the time axis with the original frequency axis to produce a filtered version of the display spectrum data.