KR101073664B1 - A Pre-Compensation Technique for Synchronization between Wireless Speakers in Multichannel Wireless Speaker Systems - Google Patents

Abstract

The present invention relates to the transmission of sound data between a wireless sound transmitter for transmitting multi-channel sound data and a wireless sound speaker for receiving and outputting sound data. More particularly, the present invention relates to a plurality of wireless sounds. The present invention relates to a method for compensating for a difference in reproduction time between wireless sound speakers generated when distributed to a speaker.

To this end, the present invention receives a plurality of data having the same reproduction time information, delays and outputs a delay length set for each channel, and wirelessly transmits a transmission packet modulating the output data to the outside through a corresponding transmission channel. The present invention proposes a TDMA based multi-channel wireless transmission system including a sound transmitter and a plurality of wireless sound speakers for receiving and reproducing a transmission packet received from the wireless sound transmitter.

TDMA, multichannel sound data, wireless sound transmitter, wireless sound speakers, time-difference compensation, null data

Description

Pre-Compensation Technique for Synchronization between Wireless Speakers in Multichannel Wireless Speaker Systems}

The present invention relates to the transmission of sound data between a wireless sound transmitter for transmitting multi-channel sound data and a wireless sound speaker for receiving and outputting sound data. More particularly, the present invention relates to a plurality of wireless sounds. The present invention relates to a method for compensating for a difference in reproduction time between wireless sound speakers generated when distributed to a speaker.

Recently, home theaters are becoming popular. A home theater literally means a movie theater that is decorated at home. It is also called a home theater. Home theater was used before DVD (Digatal Versatile Disk) was introduced, but generalized as DVD system became popular. The DVD system is excellent, providing users with picture quality and realistic sound. In particular, DVD has an advantage of providing a very realistic sound compared to conventional methods such as LD (Lager Disk), VHS (Video Home System) or VCD (Video Compact Disk). For example, in the case of Saving Private Ryan, the sound transmitted through the actual speakers in the scene of the bullet flying forward from the back is forward to back. In the Matrix, the sound transmitted through the speakers as the helicopter rolls over the head of the protagonist feels as if the helicopter is actually spinning around the head. It is multichannel digital sound that enables such stereoscopic sound. The multichannel digital sound currently used mainly is a digital channel sound known as a 5.1 channel digital sound or a six channel digital sound.

The 5.1 channel is 5.1 channels including two channels of the front left and right front, two channels of the rear left and right rear of the user, five channels of the center center channel and 0.1 channel of the subwoofer with the bass. The front channel speakers are also referred to as the main speakers, which are located in front of the viewer. The role of the main speaker is mainly responsible for the background music and the effect sound connected from the front to the left and right. In fact, the main speaker is used larger than the other speakers, which are used for the sake of stereo channel reproduction, and need not necessarily be larger than the other speakers. The center channel speaker is called the center speaker and is mainly responsible for the dialogue part of the film or the human voice, or vocal, in music. Of course, some music or sound effects are also included and delivered to the user. Center speakers are usually placed on televisions, so that they sound like the actor is talking right on the screen. The rear channel speakers are called rear speakers or surround speakers and are placed on either side of the rear of the user. The rear speakers are mainly responsible for the surround effect. In the past, surround was mono, but stereo surround was used on the 5.1 channel. On the other hand, the subwoofer is a low frequency (Low Frequency) speaker, unlike other speakers are not significantly limited in position. The reason for this is that bass sounds are less directive than mid and high notes. Most subwoofers can play up to 20 to 30Hz, while a superior subwoofer can play down to lower sounds. This bass gives you a more realistic sound reproduction as well as sound. On the other hand, the subwoofer may or may not have its own amplifier. Recently, an active type that has its own amplifier in order to obtain its own volume control and powerful sound is widely used. Meanwhile, among the speakers, except for the subwoofer, the speakers may have different positions depending on their roles, but may not be physically different. In the case of the center speaker, there are only a few differences for the metabolism of the film.

Multi-channel digital sound reproduction system has various channels such as 4 channels and 4.1 channels as well as 5.1 channels. Recently, home theaters with 6.1 channels have been introduced. When installing a home theater with multi-channel digital sound reproduction, each speaker must be connected to its own terminal.

A time division multiple access (TDMA) scheme is used for a typical radio distribution and transmission scheme for multichannel sound transmission. The TDMA-based multi-channel wireless speaker system of FIG. 1 is a technique of avoiding interference for each channel by transmitting respective sound data in a designated time slot for each speaker.

In the TDMA method, M multi-channel sound data extracted from a sound source is packetized into a section suitable for output from a wireless sound speaker (hereinafter referred to as 'WSS'), and then a speaker ID and playback information are added to the modulator. Through the radio channel to each speaker for the entire transmission time. Each WSS demodulates a radio signal received during its time slot, extracts sound data, and outputs it through a speaker. In the TDMA method, since multichannel sound data is continuously transmitted in time, in order to reproduce sound at the same time in all WSSs, after receiving signals of all channels, synchronization between speakers should be performed based on current time information and playback time information. .

For synchronization between WSSs, the current time information should be periodically transmitted from the Wireless Sound Distributor and Transmitter (hereinafter referred to as "WSDT"), and the play time information should be added to all sound packets. Each WSS receives the current time information, sets a reference time, and reproduces the data according to the reproduction time information of each packet based on the set reference time. In this structure, since the received packet must be stored in the buffer until the playback time, a storage space must be added, and a timer and a playback time control unit are required to increase the hardware complexity, and additional information for synchronization between speakers is added to every packet every time. Since it must be added, there is a disadvantage that the transmission efficiency is reduced.

The problem to be solved by the present invention is a structure that is simpler than the conventional method of the control method of the receiver by precompensating and transmitting the difference in reproduction time between the speakers, which is a problem of the conventional TDMA-based multi-channel wireless speaker system, through the delay of sound data at the transmitter. It is intended to provide a transmitter compensation scheme with

In the TDMA-based multi-channel wireless transmission system for achieving the above object, the method for transmitting data includes the step of transmitting a plurality of data having the same play time information to the corresponding delay unit, the data input to the delay unit for each channel Delaying and outputting the set delay length, generating transmission packets in which the output data is modulated, and transmitting the generated transmission packets to the outside through corresponding wireless channels in a set order.

An apparatus for transmitting data in a TDMA based multi-channel wireless transmission system for achieving the above object is a delay unit for receiving a plurality of data having the same play time information delayed by a delay length set for each channel, outputting the Modem unit for generating a transmission packet modulated with data, Communication unit for transmitting the modulated transmission packet to the outside through a corresponding transmission channel.

In order to achieve the above object, the present invention receives a plurality of data having the same reproduction time information, delays and outputs a delay length set for each channel, and outputs a transport packet modulating the output data through a corresponding transport channel. The present invention proposes a TDMA based multi-channel wireless transmission system including a wireless sound transmitter for transmitting to the outside and a plurality of wireless sound speakers for receiving and reproducing a transmission packet received from the wireless sound transmitter.

The present invention is to compensate for the transmission time error occurring between the speakers in the multi-channel wireless speaker system using TDMA in advance through the delay of the sound data in the WSDT to transmit the same playback time in all WSS without additional structure for synchronization in the WSS The sound can be reproduced, simplifying the structure of the WSS, which can be implemented with a small complexity.

In addition, the pre-compensation technique and apparatus for inter-speaker synchronization of the multi-channel wireless speaker system of the present invention does not require additional data such as current time information and playback time information for inter-speaker synchronization, thereby improving the efficiency of sound data transmission. Can provide high quality sound.

The foregoing and further aspects of the present invention will become more apparent through the preferred embodiments described with reference to the accompanying drawings. Hereinafter will be described in detail to enable those skilled in the art to easily understand and reproduce through this embodiment of the present invention.

The present invention based on TDMA proposes a method of acquiring M sound data from a WSDT, sequentially assigning the respective sound slots to each time slot, and transmitting the delayed data from the WSDT.

2 is a layout view of a speaker of a general 5.1 channel sound system.

The 5.1 channel sound system includes a left stereo channel 110, a right stereo channel 120, a left surround channel 130, a right surround channel ( 140, a single center channel 150, and a low frequency enhancement channel (LFE) 160.

3 is a diagram illustrating a transmission structure of a WSDT according to an embodiment of the present invention. Hereinafter, a transmission structure of a WSDT according to an embodiment of the present invention will be described in detail with reference to FIG. 3.

Referring to FIG. 3, when M multi-channel sounds obtained from a sound source are packetized into a section N suitable for playback in a WSS, and then subjected to modulation in a form necessary for wireless transmission, a Tx packet is generated. The time at which the transport packet is transmitted becomes T. In the M multi-channel wireless speaker system, the wireless transmission modem used in the present invention is possible because real-time transmission of sound data is possible when the time (M × T) of wireless transmission of data of all channels is smaller than the reproduction time (N) of the sound data. It is assumed that this condition is satisfied.

According to FIG. 3, the data stream of channel 1 to the data stream of channel M are transferred to the delay unit. The WSDT of the TDMA method transmits the data streams in the order of the data stream of the channel 1 and the data stream of the channel 2. The WSDT transmits the data stream of the channel 1 again after the last transmission of the data stream of the channel M in the above-described manner. do.

When the data stream of the channel 1 to the data stream of the channel M are simultaneously input, the delay unit delays and outputs the data stream of the channel 1 for a predetermined time according to a control instruction of a controller (not shown). As described above, the time for delaying the data stream of channel 1 in the delay unit is related to the number of data streams and the time required to transmit one packet among the packets obtained by dividing the data stream into a predetermined size.

The delay length delayed by the delay unit is different for each data stream of each channel. The delay unit outputs the data stream of channel 1 by delaying (M-1) x T. The delay unit delays and outputs the data stream of channel 2 by (M-2) x T, and immediately outputs the data stream of channel M, which is the last data stream, without delay.

The delay unit can be easily implemented using a buffer, and the size of the buffer can be adjusted according to the delay length. When the data stream is input to the buffer, the delayed data packet is output. However, when the data stream is smaller than the delay length of the input data stream, null data is inserted and output.

3 shows the data stream of channel 1 to the data stream of channel M output from the delay unit. The WSDT divides the data stream output from the delay unit into time units necessary for reproduction. Referring to FIG. 2, it can be seen that the WSDT divides the data stream into packets having an N size. The size of dividing the data stream in the WSDT may vary depending on the size of the user or the WSS specification.

The WSDT transmits the first packet of channel 1 for T time and then the first packet of channel 2 for T time. By repeating this process, the WSDT finally transmits the first packet of channel M, and then transmits the second packet of channel 1 again. As shown in FIG. 3, in the initial transmission, all channels except the channel M include null data, but only sound data is transmitted from the second transmission.

Referring to FIG. 3, the WSDT generates a Tx packet that can be transmitted for a T time through a modulation process of a data packet having a reproduction time of N. FIG. That is, although not shown in Figure 3, the data packet is modulated into a transmission packet (Tx packet) through a modulation process in the modulator.

4 illustrates a process of receiving a packet in a WSS according to an embodiment of the present invention. Hereinafter, a process of receiving a packet in a WSS according to an embodiment of the present invention will be described with reference to FIG. 4.

Referring to FIG. 4, when data of all channels are sequentially transmitted wirelessly, each WSS receives a transport packet corresponding to its time slot and demodulates the data packet through a demodulation process. The WSS extracts sound data from the demodulated data packet. When all of one transport packet is received, the WSS reproduces the sound data using the data packet generated through the demodulation process.

The first WSS 400 receives transport packets partitioning the first data stream, and the second WSS 402 receives transport packets partitioning the second data stream. The Mth WSS 404 receives the transport packets obtained by dividing the Mth data stream.

When the reception of the first transport packet is completed, the first WSS 400 starts playback immediately after demodulating the transport packet that has been received. Since the first part of the first packet contains null data, the actual sound is not output even if playback is started immediately. That is, since the first WSS 400 is reproduced after the time T required for packet reception and the time delayed by (M-1) x T delayed by the WSDT, the first WSS 400 is delayed by the total M x T time to output the actual sound.

When the reception of the first transport packet is completed, the second WSS 402 starts reproduction immediately after demodulating the received transport packet. Since the first part of the first packet contains null data, the actual sound is not output even if playback is started immediately. As described above, the WSDT transmits the first transport packet of the first channel from 0 to T time and the first transport packet of the second channel from T time to 2T time. That is, since the second WSS 402 is reproduced after the time 2T necessary for transmission packet reception and the time delayed by (M-2) x T delayed by the WSDT, the second WSS 402 is delayed by the total M x T time to output the actual sound.

When the reception of the first transport packet is completed, the M-th WSS 404 starts reproduction immediately after demodulating the received transport packet. Unlike the transmission packet of the other channel, the first part of the first transport packet contains null data, so the actual sound is output when the playback starts immediately. That is, since there is no delay time other than the time M × T required for transmission packet reception, the M WSS 404 is delayed by M × T time to output the actual sound. Therefore, since all WSSs are actually reproduced after a time delay of M × T, there is no need to perform an additional operation for synchronization between speakers in the WSS. Of course, it is assumed that all WSS H / W structures are identical.

Since each WSS extracts a sound directly from data received during its time slot, it does not need any additional structure and device such as current time information and play time information for synchronization between WSSs. That is, the sound system of the present invention can efficiently transmit sound data, and there is an advantage that a buffer for storing the received sound data is not required for synchronization, thereby enabling simple WSS implementation.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

1 is a block diagram schematically showing a conventional TDMA based multi-channel wireless transmission system,

2 is a speaker layout diagram of a 5.1-channel sound system;

3 is a diagram illustrating a structure of a transmitting end of a TDMA based multi-channel wireless transmission system according to an embodiment of the present invention.

4 is a diagram illustrating a structure of a receiving end of a TDMA based multi-channel wireless transmission system according to an embodiment of the present invention.

Claims (9)

A method for transmitting data in a TDMA based multichannel wireless transmission system, Transferring a plurality of data having the same reproduction time information to a corresponding delay unit; Delaying and outputting the data inputted to the delay unit by a delay length set for each transmission channel; Generating transmission packets by modulating the outputted data, and transmitting the generated transmission packets using a corresponding transmission channel according to a set transmission order. If the number of channels is' M 'and the time required to transmit one transport packet through the wireless channel is' T', the delay length of data corresponding to the 'k'-th channel is' (Mk) T' Data transmission method characterized in that. delete The method of claim 1, wherein the delay of the data is performed only before the transmission of the first transport packet for each transport channel. The data transmission method according to claim 1, wherein the time required for sequentially transmitting the transport packets of all channels once is less than or equal to the reproduction time of the demodulated transport packets. An apparatus for transmitting data in a TDMA based multichannel wireless transmission system, A delay unit receiving a plurality of data having the same reproduction time information and delaying the delay data by a delay length set for each transmission channel; A modem unit generating a transmission packet modulated with the output data; It includes a communication unit for transmitting the modulated transport packet to the outside through a corresponding transmission channel in a set transmission order, If the number of channels is' M 'and the time required to transmit one transport packet through the wireless channel is' T', the delay length of data corresponding to the 'k'-th channel is' (Mk) T' Data transmission device characterized in that. delete Receives a plurality of data having the same reproduction time information and outputs the delayed delay set for each channel, and transmits the transmission packet modulated by the output data to the outside through the corresponding transmission channel according to the set transmission order Sound transmitter; It includes a plurality of wireless sound speakers for receiving and playing the transmission packet received from the wireless sound transmitter, The wireless sound transmitter includes a delay unit, and the delay unit If the number of channels is 'M' and the time required to transmit one transport packet through the wireless channel is 'T', the delay length of the data corresponding to the 'k' channel is '(Mk) T' TDMA-based multi-channel wireless transmission system characterized by. The wireless sound transmitter of claim 7, The delay unit receiving a plurality of data having the same reproduction time information and delaying the delay data by a delay length set for each channel; A modem unit generating a transmission packet modulated with the output data; And a communication unit for transmitting the modulated transport packet to the outside through a corresponding transport channel. delete

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