CAN Repeater Emulating ACK Bit to Reduce Signal Delay
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Solution Overview
Problem
State-of-the-art CAN repeaters introduce additional delay, limiting the maximum transmission distance and data rate in CAN networks due to signal propagation time issues, especially with increased cable length or delay-causing elements, necessitating reduced data rates for reliable communication.
Innovation Solution
A CAN repeater with a logic unit that emulates an ACK bit before or during data transmission, allowing for targeted manipulation of data telegrams and reducing signal delay by sending an acknowledgment before the actual receiver's response is received, thereby increasing information density and enabling longer transmission paths without sacrificing data rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a state-of-the-art CAN repeater is used to extend transmission distance, then cable length can be increased, but signal propagation delay increases and data rate must be reduced
Solution Approach 1:
The repeater performs preliminary action by sending an emulated ACK bit before the actual receiver response is received. This anticipatory acknowledgment allows the transmitter to continue communication without waiting for the delayed receiver response, effectively decoupling the transmission timing from the propagation delay and maintaining high data rates over extended cable lengths
Solution Approach 2:
The repeater acts as an intermediary by generating an emulated ACK bit that mediates between the transmitter and receiver. This intermediate signal allows the transmitter to perceive acknowledgment timing as if the receiver responded immediately, while the actual receiver response can arrive later without disrupting the communication flow
2Length of stationary object
If a CAN repeater is introduced to extend network range, then transmission distance increases, but maximum data rate decreases due to additional propagation time
Solution Approach 1:
The repeater sends the emulated ACK bit in advance, before the actual receiver response arrives. This preliminary acknowledgment allows the transmitter to maintain its data transmission rate without being forced to slow down to accommodate the repeater-induced propagation delay, thus preserving high data rates over extended transmission distances
3Length of stationary object
If cable length is increased beyond 30-40m at 1 Mbit/s, then transmission distance increases, but ACK bit arrival time exceeds acceptable limits
Solution Approach 1:
The repeater introduces an emulated ACK bit as an intermediary signal that provides immediate acknowledgment to the transmitter. This intermediary acknowledgment decouples the transmitter's timing requirements from the actual receiver response timing, allowing cable lengths to exceed 30-40m while maintaining reliable communication at 1 Mbit/s
Solution Approach 2:
The repeater performs preliminary acknowledgment by sending the emulated ACK bit before the actual receiver response arrives. This preliminary action ensures that the transmitter receives timely acknowledgment even when the physical cable length would normally cause the ACK bit to arrive too late, thereby maintaining communication reliability
Data Source
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AI summary
The invention relates to a repeater (2, 2') for a communication system with at least one network (1, 1') for forwarding a data telegram comprising a recessive ACK bit from a first participant (A) to a second participant (B) either within the network (1) or in order to connect two similar networks (1, 1'), said repeater being designed to forward data telegrams on bit transmission levels of the ISO-OSI reference model. The repeater comprises at least two transceivers (5A, 5B) for physically coupling the repeater (2, 2') to the at least one network (1, 1'), said repeater (2, 2') comprising a logic unit (6) which is designed to detect the determined structure of a data telegram to be forwarded from the first participant (A) to the second participant (B) and to emulate an ACK bit and transmit same to the first participant (A) at a determined point in time before or while the recessive ACK bit of the data telegram is received.