Bus Collision Avoidance via Sensing Current Threshold
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In single cable satellite antenna systems, data collisions occur due to multiple masters transmitting data simultaneously, leading to data loss, and existing standards like DiSEqC do not effectively detect or prevent collisions, especially during blind channel searches where transport stream information is unknown.
Innovation Solution
A method and controller that measure the sensing current or test voltage drop on the bus to determine signal activity, applying a transmission voltage only when the current or voltage drop is above a threshold, with a delay time interval shorter than 10 ms to quickly recognize and avoid collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple masters transmit data simultaneously on the bus, then data transmission efficiency is improved, but data collision occurs leading to data loss
Solution Approach 1:
The controller performs preliminary sensing of the bus state before transmitting data by measuring voltage or current levels. This preliminary detection of signal activity allows the controller to determine whether the bus is free for transmission, preventing collisions before they occur.
Solution Approach 2:
The controller continuously monitors the bus for signal activity during and after transmission attempts. When a collision is detected through feedback from the bus state, the controller adjusts its transmission behavior by implementing random backoff delays and retrying transmission, thereby resolving the contradiction between maintaining high transmission efficiency and preventing data loss.
2Reliability
If a long random delay time is applied before retransmission after collision detection, then collision avoidance is improved, but transmission latency increases
Solution Approach 1:
Instead of using a single long random delay, the controller employs periodic sensing of the bus state at regular intervals during the backoff period. This allows the controller to detect when the bus becomes free and transmit immediately, reducing average latency while maintaining collision avoidance through the periodic check mechanism.
Solution Approach 2:
The delay time before retransmission is made dynamic rather than fixed. The controller adjusts the backoff delay based on the detected bus state and collision history, implementing shorter delays when the bus is quickly freed and longer delays when collisions are frequent, thereby optimizing both reliability and latency.
3Adaptability or versatility
If traditional DiSEqC collision detection methods are used, then standard compatibility is maintained, but collision detection capability is insufficient especially during blind channel search
Solution Approach 1:
The controller performs preliminary sensing of the bus state before transmitting DiSEqC commands during blind channel search. By measuring voltage or current levels on the bus beforehand, the controller can detect the presence of other signals and avoid collisions even when transport stream information is unavailable, enhancing collision detection capability while maintaining DiSEqC standard compatibility.
Solution Approach 2:
The patent introduces an intermediary sensing mechanism that measures voltage or current levels on the bus as an intermediate step between traditional DiSEqC command transmission and collision detection. This intermediary measurement provides additional collision detection information that enhances reliability during blind channel search without compromising standard compatibility.
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3A~3B
AI summary
A method for transmitting data over a bus, to which a plurality of receivers and/or controllers are connected comprises measuring a sensing current on the bus, and, if the sensing current is measured to be at or below a predetermined current threshold, repeating the step of measuring the sensing current after a delay time interval starting after the sensing current is measured to be at or below the predetermined current threshold, said delay time interval being shorter than 20 ms.