Full-Duplex Daisy-Chain Timing Alignment for Synchronized Audio Links
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Solution Overview
Problem
Current daisy-chain communication systems face challenges with timing adjustments due to flexible node numbers and unknown cable lengths, leading to issues with frame schedule synchronization and phase alignment, particularly in A2B systems, which do not automatically adjust response times and phase align nodes.
Innovation Solution
A daisy-chain communication system utilizing carrier-based modulation and full duplex communication with a novel mechanism that aligns audio-sample phases across nodes by measuring and adjusting response times, enabling synchronized communication within a fixed time window and supporting flexible payloads for both synchronous and asynchronous data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional one-directional ring topology is used for digital audio communication, then electromagnetic compatibility is improved, but bandwidth is limited and latency increases due to store-and-forward between nodes
Solution Approach 1:
The patent inverts the traditional one-directional ring topology by implementing full-duplex bidirectional communication on the same wire. Each node can simultaneously transmit and receive audio streams in both directions, effectively doubling the usable bandwidth while maintaining the daisy-chain physical topology that provides electromagnetic compatibility.
Solution Approach 2:
The patent adds a temporal dimension to the communication by implementing time-division multiplexing with precise timing control. Different audio streams are transmitted in different time slots within the same frequency band, increasing bandwidth capacity without requiring additional physical wires or compromising electromagnetic compatibility.
2Loss of time
If A2B line coding with time division multiplexing is used, then low latency is achieved without store-and-forward, but bandwidth is limited and improvements are needed for future applications
Solution Approach 1:
The patent changes the modulation parameter from traditional line coding to carrier-based modulation schemes. This allows for higher data rates and increased bandwidth while maintaining the low-latency characteristic of direct transmission without store-and-forward operations at intermediate nodes.
Solution Approach 2:
The patent implements periodic carrier waves with different frequencies for upstream and downstream communication. This periodic modulation enables full-duplex operation by separating transmit and receive signals in the frequency domain, increasing bandwidth while preserving the direct transmission path that ensures low latency.
3Loss of time
If daisy-chain topology is used for digital audio communication, then low latency is achieved, but timing synchronization becomes challenging with unknown cable lengths and flexible node configurations
Solution Approach 1:
The patent implements a timing synchronization protocol where each node measures the delay from its predecessor's transmission and communicates this delay information to upstream nodes. This feedback mechanism allows the network to automatically adjust timing offsets and achieve precise synchronization without requiring knowledge of cable lengths or node configurations.
Solution Approach 2:
The patent performs preliminary timing calibration during network initialization by measuring delays and calculating appropriate timing offsets for each node before actual audio transmission begins. This preliminary action ensures that all nodes are synchronized and ready for low-latency communication without requiring complex real-time adjustments.
4Productivity
If full duplex carrier-based modulation is implemented, then bandwidth increases 4 times and electromagnetic compatibility improves, but timing synchronization and phase alignment become more challenging
Solution Approach 1:
The patent uses feedback from delay measurements to automatically adjust the phase of carrier waves at each node. Each node measures the round-trip delay and uses this information to calculate the precise phase offset needed to align its transmissions with the network timing, achieving accurate phase alignment despite the complexity of full-duplex carrier-based modulation.
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 system achieves 4 times more bandwidth and improved electromagnetic compatibility, allowing all nodes to communicate within the same time window with synchronized audio sampling and supports both clock-synchronous and asynchronous data streams with low latency.
Implementation Method 1
synchronized communication via a carrier-based modulation scheme over the bus links
Data Source
AI summary
A communication system includes a plurality of nodes connected in a daisy-chain via respective bus links, wherein the plurality of nodes are configured for full duplex, synchronized communication via a carrier-based modulation scheme over the bus links. A node is configured to: transmit a downstream synchronization control header (DnSCH) to a downstream node; receive an upstream synchronization response header (UpSRH) from the downstream node; measure a delay between the DnSCH and the UpSRH; send delay information to the downstream node in a DnSCH; receive a time adjusted UpSRH; and communicate with the downstream node and any upstream node over frames based on the delay information. The frames may include a header; a flexible payload defined by a stream mapping that assigns a byte location within the flexible payload to a stream; and a footer.