Bi-Directional Amplifier Isolation Using Adaptive Digital Filtering
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Solution Overview
Problem
Bi-directional amplifiers using directional couplers face limited isolation, leading to downstream signal leakage into the upstream signal path and vice versa, especially when downstream and upstream frequencies adjoin, which degrades signal quality.
Innovation Solution
A bi-directional amplifier device with a digital processor-based isolator unit that digitally filters upstream signals to remove downstream frequencies before amplification, and optionally filters downstream signals to remove reflected upstream frequencies, thereby improving signal isolation and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If directional couplers are used to separate upstream and downstream signal paths, then signal path separation is achieved, but signal isolation is limited causing downstream signals to leak into upstream path and vice versa
Solution Approach 1:
A digital signal processor is introduced as an intermediary component between the directional coupler and the amplifier. The DSP receives the upstream signal, digitally filters out downstream frequencies using adaptive filtering algorithms, and outputs the cleaned upstream signal. This intermediary processing stage effectively blocks signal leakage that the passive directional coupler cannot prevent.
Solution Approach 2:
The patent replaces traditional passive mechanical filtering methods (such as diplex filters) with active digital signal processing. Instead of using physical filter components with fixed frequency responses, the system uses a DSP with adaptive digital filtering algorithms that can dynamically adjust to frequency changes and provide superior signal isolation.
2Productivity
If frequency ranges are altered to provide faster upstream signals, then broadband performance is improved, but signal isolation becomes more difficult when downstream and upstream frequencies are interleaved
Solution Approach 1:
The system employs adaptive digital filtering in the DSP that can dynamically adjust to changing frequency allocations. When frequency ranges are altered for faster broadband performance, the DSP automatically adapts its filtering parameters to maintain effective signal isolation between upstream and downstream paths, enabling flexible frequency planning without compromising isolation.
Solution Approach 2:
The patent utilizes programmable frequency parameters in the DSP that can be changed to match different frequency allocations. By changing the digital filter parameters adaptively, the system maintains effective signal isolation even when frequency ranges are reconfigured for improved broadband performance, allowing flexible network optimization.
3Adaptability or versatility
If downstream signal spectrum and upstream signal spectrum adjoin, then frequency utilization is maximized, but signal quality degrades due to mutual interference and reflections
Solution Approach 1:
The system uses feedback from the actual signal conditions to adjust the digital filtering parameters in real-time. The DSP monitors the upstream and downstream signals and adapts its filtering characteristics to maintain signal quality even when frequency spectra adjoin, enabling maximum frequency utilization without degradation from mutual interference and reflections.
Data Source
AI summary
There is provided a bi-directional amplifier device (10) configured for use in a broadband network comprising a first directional coupler (12) and a second directional coupler (14) connected together so as to create separate upstream and downstream paths (16, 18), an upstream amplifier element (24) located in the upstream signal path (16) and a downstream amplifier element (24′) located in the downstream signal path (18), wherein an isolator unit (40) comprising a digital processor element (56) is connected to an input (45) of the upstream amplifier element (24) and the isolator unit (40) is adapted to digitally filter the upstream signal to remove all downstream signal frequencies before amplification of the upstream signal takes place in the upstream amplifier element (24). The isolator unit (40) further comprises signal converters (58, 60) to convert analogue downstream and upstream signals into digital signals for processing by the digital processor element (56).