Data transfer method and system for loudspeakers in a digital sound reproduction system

A data transfer system for a digital sound reproduction system, said data transfer system comprising;

• a host data source for generating a digital audio stream for multiple channels, the audio stream being formed by multiple consecutive samples,
• a transmission path for the host data source,
• multiple digital receivers capable to communicate over the transmission path with the host data source, the receivers including
• a means for receiving the digital audio stream sent by the host data source
• a microcontroller with a clock, and
• a means for generating an audio signal out of the digital audio stream,
• wherein the host data source has means for initiating synchronization of the receivers by sending repeatedly a synchronization sample to each of the receivers,
• wherein each receiver has means for replying to the synchronization sample by a return sample,
• wherein the host data source further includes means for
• calculating a latency (T) for each receiver based on the sending time (Th1) of the synchronization sample and the reception time (Th2) of the return sample and a processing time (Tt2-Tt1) of the receiver, which processing time (Tt2-Tt1) is the time the receiver spent between receipt of the synchronization sample and sending of return sample,
• sending to the each receiver information on an estimate of the clock of the host data source at the time the receiver received the synchronization sample,
• whereby based on this information each receiver includes means for adjusting the function of its clock,
• the system includes means for repeating the above synchronization steps continuously, and
• wherein the host data source includes means for comparing the calculated latency (T) with a reference latency and if the calculated latency (T) is larger than the reference latency, no adjustment information is sent to the receiver and the host data source starts a routine to redefine the reference latency.

A synchronization method in a digital sound reproduction system comprising the steps of;

• generating a digital audio stream in a host data source, the audio stream is formed by multiple consecutive samples,
• receiving the digital audio stream sent by the host data source through a digital data transmission network by several digital receivers each of which including a microcontroller with a clock, the receivers further including means for generating an audio signal out of the digital audio stream, whereby the receivers are grouped in a predetermined manner,
• initiating, by the host data source, synchronization of the receivers of a group by sending repeatedly a synchronization sample to all receivers of a group,
• replying, by the receivers of the group, to the synchronization samples by return samples,
• calculating, by the host data source, a latency time (T) for each sample and each receiver of the group based on sending time (Th1) of the synchronization sample and the reception time (Th2) of the return sample and a processing time (Tt2-Tt1) of the receiver, which processing time (Tt2-Tt1) is the time the receiver spent between receipt of the synchronization sample and sending of return sample,
• statistically forming a reference latency value, by the host data source, based on the calculated latency times (T) and
• comparing the calculated latency times (T) with the reference latency value and if the calculated latency (T) is larger than the reference latency value, the host data source starts a routine to redefine the reference latency value.