Adaptive Filter Mode Switching for Noise Reduction in Digital Receivers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional digital receiving devices face challenges in effectively reducing ambient noise without increasing the circuit size, particularly in radio communication systems.
Innovation Solution
A digital receiving device and radio communication system that employ an adaptive filter with both adaptive and non-adaptive modes, where the filter coefficient is updated during non-communication state periods to remove ambient noise, and the system controls the operation between these modes to optimize noise reduction without requiring additional circuitry for noise signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the adaptive filter continuously updates the filter coefficient to remove ambient noise, then the noise reduction effectiveness is improved, but the desired signal may be distorted when noise and signal are correlated
Solution Approach 1:
The adaptive filter dynamically switches between adaptive mode and non-adaptive mode based on the detection of specific codes. During non-communication state periods, the filter operates in adaptive mode to remove noise, while during signal reception, it switches to non-adaptive mode to preserve signal integrity. This dynamic operation resolves the contradiction by adapting the filter behavior to the current state.
Solution Approach 2:
The system utilizes periodic non-communication state periods (insertion periods) where specific codes are transmitted instead of communication signals. During these periodic intervals, the adaptive filter updates its coefficients to track noise characteristics, then applies these coefficients during communication periods to reduce noise without distorting the desired signal.
2Object-affected harmful factors
If additional antenna and circuit are added to receive and process noise signal separately, then the noise reduction capability is improved, but the circuit size and complexity increase
Solution Approach 1:
The single antenna and adaptive filter are designed to perform multiple functions: receiving both communication signals and noise, and operating in both adaptive and non-adaptive modes. This multi-functionality eliminates the need for separate noise-receiving antennas and dedicated noise processing circuits, thereby reducing circuit size while maintaining noise reduction capability.
Solution Approach 2:
The adaptive filter uses the received signal containing both desired signal and ambient noise to automatically adapt and remove noise during non-communication periods. The system serves itself by utilizing the existing received signal for both communication purposes and noise characterization, without requiring additional dedicated noise reception hardware.
3Duration of action of stationary object
If the filter coefficient is updated during signal reception, then the noise removal is continuous, but the signal processing time is lost and computation overhead increases
Solution Approach 1:
The adaptive filter updates coefficients periodically during non-communication state periods rather than continuously during signal reception. This periodic updating approach ensures noise removal effectiveness while preserving signal processing time, as the filter operates in non-adaptive mode during communication periods to avoid computation overhead.
Data Source
AI summary
A digital receiving device includes a detecting means for detecting a specific code under a signal receiving state capable of successively receiving a desired signal, a setting means for setting a period for detecting the specific code as a non-communication state period, an adaptive filter having an adaptive mode and a non-adaptive mode, the adaptive mode by which a filter coefficient is sequentially updated so as to remove an ambient noise during the non-communication state period, and the non-adaptive mode by which the filter coefficient is stopped from being updated during a period except for the non-communication state period under the signal receiving state and a filter controlling means for controlling an operation for switching the adaptive mode and the non-adaptive mode of the adaptive filter.