Multi-System Receiver Filtering for Adjacent Channel Synchronization
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Solution Overview
Problem
Conventional multi-system digital broadcast signal receiving devices require high-order digital low pass filters to accurately receive DAB signals, leading to increased costs and potential interference from adjacent channel signals, which complicates synchronization and FFT operations.
Innovation Solution
The implementation of a receiving device with two low pass filters of different bandwidths, where a lower order first low pass filter processes DAB signals and a second low pass filter filters out adjacent channel signals, allowing for correct synchronization and demodulation without the need for high-order filters, thereby reducing overall costs and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-order digital low pass filter is used to receive DAB signals, then signal reception accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The patent divides the filtering function into two separate filters: a first low pass filter for DAB signal reception and a second low pass filter for ACS interference removal. This segmentation allows each filter to operate at a lower order than a single high-order filter would require, reducing overall device complexity while maintaining signal reception accuracy.
Solution Approach 2:
The patent introduces an intermediary signal processing stage where the output of the first low pass filter is processed by a second low pass filter to remove ACS interference. This intermediary step enables the system to achieve high signal reception accuracy without requiring a single high-order filter, thus reducing device complexity.
2Object-affected harmful factors
If a high-order digital low pass filter is used to filter DAB signals, then adjacent channel signal interference is reduced, but device cost increases
Solution Approach 1:
The patent segments the interference filtering function into two parts: the first low pass filter handles DAB signal bandwidth limiting, and the second low pass filter specifically targets ACS interference removal. This segmentation allows effective interference reduction without requiring a single high-order filter, thereby reducing device cost.
Solution Approach 2:
The patent extracts the ACS interference removal function as a separate second low pass filter stage, distinct from the main DAB signal filtering performed by the first low pass filter. This extraction allows targeted interference reduction with lower-order filters, reducing overall device cost.
3Device complexity
If a lower order digital low pass filter is used, then device cost is reduced, but synchronization detection accuracy deteriorates
Solution Approach 1:
The patent segments the signal processing into two filtering stages, where the first low pass filter uses a relaxed bandwidth to reduce order and cost, while the second low pass filter provides the necessary sharp cutoff to protect synchronization detection accuracy. This segmentation allows lower-order filters to be used without sacrificing detection accuracy.
Solution Approach 2:
The patent introduces an intermediary second low pass filter stage that processes the output of the first filter. This intermediary filter provides the additional frequency selectivity needed to protect synchronization detection, allowing the first filter to operate at a lower order for cost reduction.
4Device complexity
If a single filter is used for both DAB and DVB signals, then device complexity is reduced, but adaptability to different bandwidth requirements deteriorates
Solution Approach 1:
The patent implements a dynamic filtering architecture where the first low pass filter bandwidth is adaptively configured based on the received signal type (DAB or DVB). For DAB signals, a wider bandwidth (e.g., 1.8 MHz) is used, while for DVB signals, a narrower bandwidth (e.g., 7 MHz) is applied. This dynamic adaptation maintains versatility without requiring separate dedicated filters for each standard.
Solution Approach 2:
The patent changes the bandwidth parameter of the first low pass filter according to the signal standard being received. By dynamically adjusting the filter bandwidth parameter, the system achieves adaptability to different DAB and DVB bandwidth requirements while using a unified filter architecture, reducing overall device complexity.
Data Source
AI summary
A receiving device includes: a first signal processor, for receiving a radio frequency signal, and converting the radio frequency signal to generate a first signal, where the radio frequency signal includes a plurality of frames; a second signal processor, coupled to the first signal processor, for performing a Fourier transform operation on the first signal according to a synchronization signal to generate an output signal; a first filter, coupled to the first signal processor, for filtering the first signal to generate a second signal; and a synchronization detection circuit, coupled to the first filter, for detecting the second signal to generate the synchronization signal. The first signal includes a channel signal and at least a portion of neighboring channel signals from neighboring channels, and the output signal corresponds to the channel signal.