Capacitive Hybrid Transmission Arrangement for Echo Suppression
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Solution Overview
Problem
Full-duplex communication systems face challenges in echo suppression due to the simultaneous use of carriers for both transmission and reception, leading to interference and background noise, which existing hybrid designs struggle to address effectively, especially with the introduction of VDSL2 and its complex transmission profiles.
Innovation Solution
A new capacitive hybrid design is proposed, featuring two adders with opposite-polarity signal handling and low-capacitance capacitors to achieve low insertion loss and high isolation, along with a matching resistor and adjustment circuit to match the transmission medium's impedance, reducing thermal noise and improving Signal-to-Noise Ratio (SNR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional hybrid network with transformer-based or resistor-based design is used, then echo suppression is achieved, but the frequency range is limited and insertion loss is high
Solution Approach 1:
The patent changes the fundamental parameters of the hybrid network by replacing transformer-based or resistor-based designs with a capacitive hybrid architecture. This involves using capacitors with specific reactance values that can be adjusted to match different frequency ranges, thereby expanding the operational bandwidth while maintaining echo suppression performance through parameter optimization rather than structural redesign.
Solution Approach 2:
The patent employs a composite approach by combining capacitive elements with resistive components in a hybrid configuration. The capacitive hybrid network integrates capacitors with specific reactance characteristics alongside matching resistors to achieve both wide frequency response and effective echo cancellation, creating a composite structure that leverages the advantages of different component types.
2Reliability
If transformer-based hybrid design is used, then echo suppression is achieved, but device size and complexity increase
Solution Approach 1:
The patent substitutes the mechanical/physical transformer-based system with an electrical capacitive system. By replacing transformers (which are bulky mechanical components requiring magnetic cores and windings) with capacitive elements and resistors, the design achieves similar echo suppression functionality with significantly reduced physical size and structural complexity, while maintaining electrical performance.
3Reliability
If analog filtering is used to separate receive signal from echo signal, then echo suppression is achieved, but it is no longer viable with VDSL2 and intertwined frequency bands
Solution Approach 1:
The patent changes the operational parameters of the hybrid network to work with intertwined frequency bands by using capacitors with reactance values that can be tuned across the VDSL2 frequency spectrum. This allows the capacitive hybrid to effectively suppress echo signals even when downstream and upstream bands overlap, replacing the fixed-frequency analog filtering approach with an adaptable capacitive reactance-based solution.
4Reliability
If the hybrid network is designed to suppress immediate transmit voltage, then direct echo is reduced, but delayed reflections from impedance mismatches cannot be suppressed
Solution Approach 1:
The patent incorporates feedback mechanisms by designing the capacitive hybrid network with capacitors whose reactance can be dynamically adjusted or optimized to account for reflected signals. The feedback capability allows the system to adapt to impedance mismatches and suppressed delayed reflections by tuning the capacitive reactance values to counteract the effects of signal reflections from bridged taps and passive couplers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The capacitive hybrid design operates across a wider frequency range with low insertion loss, high isolation, and reduced noise, enhancing data throughput and achieving better echo suppression compared to traditional transformer-based or resistor-based hybrids.
Implementation Method 1
The first capacitors have a reactance value that matches the difference between the reactance values of the second and third capacitors
Implementation Method 2
The first impedances individually comprise a first resistor coupled in parallel with a first capacitor
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The present invention relates to a transmission arrangement (100) for coupling a pair of transmit output terminals (101, 102) to a pair of medium terminals (103, 104) coupled a transmission medium (40), and the pair of medium terminals to a pair of receive input terminals (105, 106), the pairs of transmit output terminals, receive input terminals and medium terminals carrying opposite-polarity signals (±VTX; ±VRX; ±VLINE) . In accordance with an embodiment of the invention, the transmission arrangement comprises a first adder (110) and a second adder (120) with respective first and second adder input terminals (111, 121; 112, 122) and respective adder output terminals (114; 124). The pair of transmit output terminals is coupled to the pair of first adder input terminals, and is further coupled through respective first impedances (Z1) to the pair of second adder input terminals and to the pair of medium terminals, with the first and second adder input terminals being respectively coupled to opposite-polarity transmit output terminals. The pair of receive input terminals is coupled to the pair of adder output terminals. The first impedances individually comprise a first resistor (R1) coupled in parallel with a first capacitor (C1). The first and second adders individually comprise second and third capacitors (C2, C3) between the respective first and second adder input terminals and a common terminal (115; 125), and a feedback network between the adder output terminal and the common terminal. The first capacitors have a reactance value that matches the difference between the reactance values of the second and third capacitors.