Parallel IF Filter Synchronization Detection for Frequency Offset Tracking
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Solution Overview
Problem
Existing systems take time to set the local frequency and pull the intermediate frequency into the frequency band of the filter, especially when dealing with varying receiving frequencies across different communication terminals.
Innovation Solution
A synchronization detection apparatus that uses a band limitation unit with multiple filters having different center frequencies, a detection and demodulation unit, a synchronization detection unit, and a synchronization evaluation unit to quickly adjust to frequency deviations by selecting the optimal filter based on correlation values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the local frequency is varied to follow frequency deviation of received signals, then the intermediate frequency can be aligned with the filter center frequency, but it takes time to set the local frequency and pull the intermediate frequency into the filter band
Solution Approach 1:
The patent divides the frequency tracking function into multiple parallel filter paths, each tuned to a different center frequency. Instead of varying a single local oscillator frequency, the system segments the frequency range and uses multiple fixed-frequency filters to simultaneously cover possible frequency deviations, eliminating the time-consuming frequency adjustment process.
Solution Approach 2:
The patent pre-configures multiple filters with different center frequencies before signal reception. This preliminary setup allows the system to immediately handle frequency deviations without needing to adjust frequencies in real-time, as the appropriate filter is already in place to receive signals at any expected frequency offset.
2Adaptability or versatility
If the local frequency is varied for each terminal with different receiving frequencies, then frequency alignment can be achieved, but it causes additional time delay in frequency setting
Solution Approach 1:
The patent creates a universal frequency handling mechanism where multiple filters with different center frequencies work together to serve all terminal types. This multi-functional filter bank can simultaneously accommodate signals from terminals with various receiving frequencies without requiring individual frequency adjustment for each terminal, achieving both adaptability and speed.
3Productivity
If a single filter is used for frequency selection, then the circuit configuration is simple, but it cannot quickly follow frequency deviations of intermediate frequencies
Solution Approach 1:
The patent segments the frequency selection function across multiple parallel filter paths. Each filter handles a specific frequency range, and the system switches between or combines these segmented paths based on the received signal's frequency. This segmentation enables rapid frequency tracking by simply activating the appropriate pre-configured filter segment rather than dynamically adjusting a single filter.
Data Source
AI summary
Provided are a synchronization detection apparatus, a synchronization detection method, and a synchronization detection program that make it possible to follow, in a short time, a frequency deviation of an intermediate frequency after a radio frequency is down-converted. A synchronization detection apparatus according to the present invention includes: a band limitation unit in which, for an externally received signal, each of a plurality of filters each having a different center frequency limits a band of the received signal to output a plurality of band-limited signals; a detection and demodulation unit that detects and demodulates each of the plurality of band-limited signals to output a plurality of detected signals; and a synchronization detection unit that performs synchronization detection of each of the plurality of detected signals to output a plurality of correlation values.