Channelizer Filter Coefficient Modulation for Spectrum Gap Coverage
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Solution Overview
Problem
Conventional channelizers suffer from spectrum gaps that lead to data loss, particularly in critically sampled systems, and oversampling increases processing complexity and resource requirements.
Innovation Solution
Modulating filter coefficients in a frequency channelizer using a modulation scheme to sweep the center frequency of each channel, thereby masking spectrum gaps and ensuring full spectrum coverage, with optional down-sampling and frequency offset compensation for accurate data recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oversampling is used to fill spectrum gaps, then signal detection accuracy is improved, but processing complexity and resource requirements increase
Solution Approach 1:
The patent applies dynamics by making the filter coefficients time-varying through modulation. The coefficients are dynamically adjusted according to a modulation scheme (e.g., PN sequence) to sweep the channelizer spectrum over time, allowing critical sampling to effectively cover the full bandwidth without requiring oversampling, thus reducing processing complexity while maintaining detection accuracy
Solution Approach 2:
The patent changes the parameters of the filter bank by modulating the center frequencies and bandwidths of individual channels over time. This parameter modulation allows the system to use critical sampling rates while still achieving full spectrum coverage through time-varying filter characteristics, avoiding the need for higher sampling rates
2Device complexity
If critically sampled channelizer is used to reduce resources, then processing complexity decreases, but spectrum gaps cause data loss
Solution Approach 1:
The patent makes the filter bank dynamic by modulating coefficients according to a known sequence. This allows critically sampled channels to sweep through different frequency positions over time, ensuring that signals falling into spectrum gaps at one moment are captured by adjacent channels at other moments, thereby eliminating data loss while maintaining low processing complexity
Solution Approach 2:
The patent employs periodic modulation of filter coefficients using sequences such as PN sequences. This periodic action causes the channelizer spectrum to sweep through the full bandwidth in a systematic manner, ensuring complete signal detection without gaps while using only critical sampling rates
3Area of stationary object
If filter coefficients are modulated to sweep center frequencies, then spectrum coverage is improved, but frequency offset compensation is required
Solution Approach 1:
The patent incorporates feedback mechanisms where the modulated channelizer outputs are processed with frequency offset compensation. The known modulation sequence enables estimation and correction of frequency offsets, allowing the system to achieve full spectrum coverage through coefficient modulation while compensating for the introduced frequency errors in the signal path
Data Source
AI summary
Circuit and method for modulating filter coefficients of a frequency channelizer having a filter bank include: receiving a wide spectrum input signal; modulating the filter coefficients of the filter bank to sweep a center frequency of each channel of the frequency channelizer, using a modulation scheme; and inputting frequency offset compensation caused by the modulation, and output signals of the frequency channelizer to an application processing circuit to convert the output signals to their original center frequencies.