Differential Two-Wire Communication Line Impedance Reducer
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Solution Overview
Problem
In vehicle communication systems using differential two-wire communication lines, reflected waves caused by impedance mismatches at branch points lead to signal distortion and erroneous data reception, particularly after the completion of data transmission, which existing impedance matching techniques fail to adequately address.
Innovation Solution
A communication system with nodes equipped with a reducer that temporarily reduces the impedance of the communication lines or the impedance between them immediately after data transmission is completed, using switches and resistors to absorb reflected waves and prevent erroneous data reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impedance matching resistors and capacitors are interposed between the main transmission path and each branch wiring to suppress reflected waves during data transmission, then reflected waves during transmission are suppressed, but reflected waves occurring immediately after completion of sending-out operation cannot be reduced
Solution Approach 1:
The impedance reduction is performed in advance before the reflected waves can cause erroneous data reception. By reducing the impedance immediately after data transmission completion, the system prepares the communication line in advance to absorb reflected waves before they affect subsequent reception operations.
Solution Approach 2:
The impedance of the communication line is made dynamic rather than static. The impedance reduction is temporarily activated only during the specified period after data transmission completion, allowing the system to adapt the impedance characteristics based on the operational state (transmission vs. reception phase).
2Reliability
If impedance matching is focused on the state where communication lines are not subjected to transmission of frame data, then reflected waves after transmission are reduced, but the degree of freedom for designing lengths of communication lines and topology is limited
Solution Approach 1:
The impedance reduction is temporarily activated only during the specified period after data transmission completion, allowing the system to adapt the impedance characteristics based on the operational state (transmission vs. reception phase).
Solution Approach 2:
The impedance parameter is changed dynamically based on the operational state. During data transmission, the impedance remains at its normal value allowing design freedom, while after transmission completion, the impedance is reduced to suppress reflected waves, achieving both design flexibility and reliability.
3Object-generated harmful factors
If conventional impedance matching techniques are used, then reflected waves during data transmission are suppressed, but erroneous data reception cannot be sufficiently avoided in large-size networks
Solution Approach 1:
The impedance reduction is performed in advance before the reflected waves can cause erroneous data reception. By reducing the impedance immediately after data transmission completion, the system prepares the communication line in advance to absorb reflected waves before they affect subsequent reception operations.
Solution Approach 2:
The impedance reduction action continues for a specified period after data transmission completion to ensure that all reflected waves are absorbed before the system transitions to reception mode, maintaining continuous protection against erroneous data reception.
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
Effectively suppresses reflected waves and prevents erroneous data reception by quickly stabilizing the communication line impedances to their idle state after data transmission, improving the design freedom for communication line lengths and topology in large networks.
Implementation Method 1
a reducer arranged to at least one of the nodes to reduce either an impedance of each of the first and second communication lines or an impedance between the first and second communication lines during a specified period of time starting at a time instant when, of the plurality of nodes, a node completes sending out the frames of data to be transmitted
Data Source
AI summary
A communication system includes a network, plural nodes, and a reducer. The network includes a main line and a plurality of branch lines branched from the main line respectively, the main line and each of the branch lines being respectively formed into a differential two-wire type of communication line consisting of a first communication line and a second communication line. The plural nodes are connected to two or more branch lines of the plurality of branch lines to communicate frames of data among the branches with each other. The reducer is connected to each node to reduce either an impedance of each of the first and second communication lines or an impedance between the first and second communication lines during a specified period of time starting at a time instant when a node completes sending out frames of data to be transmitted.