Time-Synchronized Audio Reproduction via Wi-Fi TSF Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sound reproduction systems struggle to synchronize internal clocks across multiple devices for simultaneous audio stream reproduction in asynchronous network environments, as they require isochronous transmission which most networks do not provide.
Innovation Solution
The system synchronizes internal clocks of sound reproduction devices by receiving Time Synch Function (TSF) signals from a single Wi-Fi network with a shared BSSID address, using a phase-locked loop to control the clock output signal, allowing for synchronized audio sample reproduction even in asynchronous networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If isochronous transmission is used to synchronize audio samples, then synchronized reproduction is achieved, but network compatibility is limited since most networks do not provide isochronous transmission
Solution Approach 1:
The patent introduces TSF signals from Wi-Fi beacons as an intermediary time reference. Instead of requiring direct isochronous transmission between devices, each device independently receives TSF signals from the access point and uses them to synchronize its internal clock, enabling synchronized audio reproduction over asynchronous networks.
Solution Approach 2:
The patent replaces the mechanical/isochronous transmission system with an electronic/software-based solution using TSF signal processing. A phase-locked loop (PLL) is used to lock the internal clock to the TSF signal, substituting complex transmission timing requirements with a software-based time reference system.
2Manufacturing precision
If internal clocks are synchronized using external time references, then simultaneous audio reproduction is achieved, but additional synchronization infrastructure is required
Solution Approach 1:
Each audio device independently receives and processes TSF signals from the Wi-Fi access point to synchronize its own internal clock. Devices do not need to exchange synchronization information with each other; they independently reference the common TSF signal, eliminating the need for complex peer-to-peer synchronization infrastructure.
Solution Approach 2:
The Wi-Fi access point's beacon function, which already transmits TSF signals for network timing purposes, is leveraged for audio synchronization as well. This multi-functional use of the existing beacon infrastructure avoids adding dedicated synchronization hardware or protocols.
3Manufacturing precision
If devices exchange time offset information to synchronize clocks, then initial synchronization is achieved, but ongoing synchronization drift cannot be corrected
Solution Approach 1:
The phase-locked loop continuously monitors the phase difference between the internal clock and the TSF signal, and automatically adjusts the internal clock frequency to eliminate drift. This continuous feedback mechanism ensures long-term synchronization accuracy without requiring periodic re-synchronization exchanges between devices.
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
This approach ensures perfect and permanent synchronization of audio stream reproduction across devices, enabling synchronized playback in networks that do not support isochronous transmission.
Implementation Method 1
the means of controlling the internal clock includes a phase-locked loop to obtain a clock output signal synchronized with the TSF signal
Data Source
AI summary
The sound reproduction installation (10) includes sound reproduction equipment (12, 14), each comprising:an internal clock (22);means (20) for receiving synchronization time information;means (30) for receiving an audio stream to be reproduced, including time reproduction information; andmeans (52) for audio reproduction of the audio stream on the basis of the internal clock (22).The means (20) for receiving time synchronization information are able to receive the TSF signals from a single Wi-Fi network (16) having a single BSSID address for all the equipment (12, 14), and each piece of equipment (12, 14) includes means (26) for slaving the internal clock (22) to the TSF signal received.