JPH07143083A - Data transmitter - Google Patents

Abstract

PURPOSE:To make it possible to realize the increase of the number of channels corresponding to the kind of music at low cost in a data transmitter which is used for the broadcasting device broadcasting music to each seat within the passenger rooms of an airplane or a train. CONSTITUTION:The sound signals from plural sound signal sources T1 to Tn are subjected to digital conversion and transmitted in a time division multiplex form from a transmitter 23. The channels of desired sound signal sources are extracted on the side of each of plural receivers 24 and are made soundible. In this broadcasting device 22, a changeover switch S is provided for only one sound signal source T1 and the sound signal from a microphone T0 is selectively outputted. When the interruption is performed from the microphone, a discrimination signal showing the interruption is also multiplexed and transmitted and the channel separation circuit 32 on the side of the receiver 24 is forcedly switched to the channel of the sound signal source T1. Thus, the increase of the number of channels can be efficiently coped with by one changeover switch S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission apparatus preferably used for a multi-channel music broadcast using headphones or the like in a cabin of an airplane or a train.

[0002]

2. Description of the Related Art In recent years, in a passenger compartment such as an airplane or a train, a broadcasting apparatus is installed which allows users to enjoy music by inserting a plug such as an earphone or a headphone into a jack provided in each seat. In such a device, a passenger selects a desired channel from a broadcast performed on a plurality of channels corresponding to a genre of music, for example, by operating a button.

In such a broadcasting apparatus, the signal lines of the respective channels must be routed in parallel to the respective seats. Therefore, when the number of channels increases, the number of wiring lines also increases. In order to eliminate such problems and improve the sound quality, the audio signals of each channel are converted to digital,
A configuration has been proposed in which time division multiplexing is performed and transmission is performed.

FIG. 5 is a block diagram showing an electrical configuration of a broadcasting device 2 having such a conventional data transmission device 1. The data transmission device 1 generally includes a transmitter 3, a plurality of receivers 4 provided in each seat, and a transmission line 5 connecting the transmitters 3 and the plurality of receivers 4. It is equipped with.

The transmitter 3 is provided for each channel such as a music genre, and is transmitted from acoustic signal sources t1, t2, ..., Tn realized by a magnetic tape reproducing device or a compact disc reproducing device. An analog audio signal is being input. The analog audio signals are provided with changeover switches s1, s2, which are individually provided for each channel.
, Sn each of which is applied to one of the input terminals of the analog / digital converters ad1, ad2 ,.
Is input to the multiplexing circuit 6 via each of.

The multiplexing circuit 6 time-divisionally multiplexes the input n-channel digital audio signal to generate a frame synchronization signal, a data signal, and a clock signal, which are sent to the encoder 8 via the line 7. input. Encoder 8
Generates a code signal obtained by multiplexing an acoustic signal from the input signal, and outputs the code signal to the decoder 11 of the receiver 4 via the transmission line 5.

The decoder 11 restores the code signal into the frame synchronization signal, the data signal and the clock signal, and outputs the code signal to the channel separation circuit 13 via the line 12. The channel separation circuit 13 extracts only the digital audio signal of the channel corresponding to the selection operation from the selection circuit 14 realized by an up / down switch or the like, and outputs it to the digital / analog converter 15. The acoustic signal that has been analog-converted by the digital / analog converter 15 is applied to the headphone 19 from the power amplifier 16 via the jack 17 and the plug 18 to be sonicated.

The transmitter 3 is also provided with a switching control circuit 9 to which the voice signal from the microphone t0 is input. The voice signal from the microphone t0 also receives the changeover switches s1.
To sn are commonly applied to the other input terminals. When the switching control circuit 9 detects a voice signal from the microphone t0, the switching control circuit 9 outputs a switching signal to each of the switching switches s1 to sn via the control signal line 10. When the changeover signal is input, the changeover switches s1 to sn cut off the acoustic signals from the corresponding acoustic signal sources t1 to tn,
Instead, the audio signal from the microphone t0 is output to the analog / digital converters ad1 to adn.

In this way, it is possible to broadcast music on a plurality of channels, and also to broadcast, for example, arrival guidance, by interrupting all channels so that each passenger does not overlook.

[0010]

In the above-mentioned prior art,
The switching circuits s1 to sn require only the number of channels. Therefore, if the number of channels is increased to provide a more advanced music broadcasting service, there is a problem that the circuit scale becomes large and the cost increases.

An object of the present invention is to provide a data transmission device which can efficiently cope with an increase in the number of channels.

[0012]

According to the present invention, data signals from a data signal source of a plurality of channels are time-division multiplexed in a transmitting means, serially transmitted via a transmission line, and a receiving means and a selecting means. In a data transmission device adapted to extract the data signal of the selected channel,
An interrupt data signal source for generating an interrupt data signal prioritizing each of the data signals, and a data signal source of a predetermined channel and the transmitting means are interposed between the data signal and the interrupt data signal. A switching means for preferentially inputting an interrupt data signal from a power source to the transmitting means; and a control signal for controlling the switching means and multiplexing an identification signal indicating that the interrupt data signal is being transmitted to the transmitting means. When the identification signal is received by the identification signal source that is transmitted in the form of a transmission signal and is received in response to the identification signal, the receiving unit is caused to select the predetermined channel regardless of the selection output from the selection unit. And a control means for extracting an interrupt data signal.

Further, the identification signal of the present invention is transmitted in place of the least significant bit of the data signal of the predetermined channel.

[0014]

According to the present invention, the data signals from the data signal sources of a plurality of channels such as acoustic signals are time-division multiplexed in the transmitting means and serially transmitted via the transmission line,
When the data signal of an arbitrary channel is extracted by the receiving means and the acoustic signal is reproduced, for example, the switching means is interposed between the data signal source of one predetermined channel and the transmitting means.

An interrupt data signal such as a voice signal of a guidance broadcast is input to the switching means from an interrupt data signal source. The interrupt data signal should be transmitted prior to the data signal from the data signal source. Therefore, the transmission means is provided with an identification signal source for determining whether or not the interrupt data signal is transmitted.

The identification signal source switches the switching means in response to the input of the interrupt data signal or the like, and replaces the data signal from the data signal source of the predetermined channel with the transmitting means and interrupts the interrupt signal. The interrupt data signal from the data signal source is input, and at the same time, the transmitting means multiplexes and transmits the identification signal indicating that the interrupt data signal is being transmitted.

Correspondingly, on the receiving means side, a control means is provided in association with the transmission line. Upon receiving the identification signal, the control means causes the receiving means to select the predetermined channel regardless of the selection output from the selecting means. Therefore, even if the data signal of the predetermined channel is not received by the receiving means, when the transmission of the interrupt data signal is started, the receiving means side automatically switches the channel and outputs the interrupt data signal. Extract.

Therefore, even if the number of channels to be transmitted is increased, only one switching means for switching between the data signal from the data signal source and the interrupt data signal from the interrupt data signal source may be provided. It is possible to efficiently cope with the increase in the number.

Further preferably, the identification signal is transmitted in place of the least significant bit of the data signal of the predetermined channel. That is, whether or not the interrupt data signal is transmitted can be represented by 1 bit, whereby the data signal transmitted as described above is an acoustic signal, and the number of bits thereof is, for example, 16 bits or 14 bits. Then, the identification signal can be transmitted without increasing the total number of transmission bits by using the least significant bit that hardly affects the reproduced sound.

[0020]

FIG. 1 is a block diagram showing the electrical configuration of a broadcasting device 22 including a data transmission device 21 according to an embodiment of the present invention. The broadcasting device 22 is used in a cabin of an airplane or a train, and a headphone 40 is used to reproduce sound of an arbitrary channel for each seat through a plug 39 connected to a jack 38 provided for each seat. It is possible.

The data transmission device 21 generally includes a transmitter 23 and a plurality of receivers 24 provided for each seat.
And a transmission line 25 that connects the transmitter 23 and each receiver 24. Acoustic signals from acoustic signal sources T1, T2, ..., Tn of a plurality of channels which are data signal sources and are classified according to music genres are input to the transmitter 23.

In the transmitter 23, the analog / digital converters AD1 and AD are individually associated with the respective channels.
, ..., ADn are provided, and the acoustic signals from the corresponding acoustic signal sources T2 to Tn are directly input to the analog / digital converters AD2 to ADn. On the other hand, the acoustic signal from the acoustic signal source T1 is input to one terminal of the analog / digital converter AD1 via the changeover switch S. The other terminal of the changeover switch S has a microphone T0 which is an interrupt data signal source.
The audio signal which is the interrupt data signal is input from the.

The voice signal is also input to the switching control circuit 30 which is the identification signal source. This switching control circuit 3
0 transmits an identification signal to the changeover switch S and the multiplexing circuit 26 while the voice signal is being input. In response to the identification signal, the changeover switch S replaces the acoustic signal from the acoustic signal source T1 with the analog / digital converter A for converting the audio signal from the microphone T0.
Output to D1.

Each analog / digital converter AD1 to AD
The audio signal and the audio signal digitally converted by n are time-division multiplexed in the multiplexing circuit 26. Each of the analog / digital converters AD1 to ADn
Converts the input acoustic signal or audio signal into a data signal of 32 bits in total, for example, 16 bits for each of the left and right channels. Therefore, from the multiplexing circuit 26,
When the number of channels n is 4, the signals shown in FIGS. 2 (1) to 2 (3) are output to the lines L1 to L3, respectively.

That is, as shown in FIG. 2A, the frame synchronization signal is transmitted to the line L1 at every data transmission period W1 of all channels. Therefore, the frequency of this frame synchronization signal is the same as the sampling frequency of each of the analog / digital converters AD1 to ADn, for example, 44.1 kHz.

A data signal as shown in FIG. 2B is transmitted to the line L2. This data signal is approximately 16 signals corresponding to the left and right sounds for each channel.
Each bit consists of 32 bits of data,
First-channel data indicated by reference numeral D1, followed by 1-bit identification data D0 indicated by reference numeral D0 in response to the identification signal from the switching control circuit 30, and 32 bits for each of the remaining three channels. Data D2
And D4.

Further, as shown in FIG. 2C, the line L3 is output with 32.times.4 + 1 = 129 pulses per period W1 and therefore a clock signal of about 5.69 MHz. An encoder 28, which constitutes a transmitting means together with the multiplexing circuit 26, creates a code signal based on the signals transmitted through these lines L1 to L3, and transmits it to the receiver 24 through the transmission line 25.

In the receiver 24, the code signal is restored in the decoder 31 into the frame synchronization signal, the data signal and the clock signal, and the lines L11 and L11, respectively.
It is input to the channel separation circuit 32 via ~ L13.
The decoder 31 and the channel separation circuit 32 constitute a receiving means. The respective signals restored by the decoder 31 are also input to the interrupt detection circuit 33 via the lines L31 to L33, respectively. The interrupt detection circuit 33 reads the identification data D0 output subsequently to the data D1 of the first channel in the data signal in response to the frame synchronization signal and the clock signal, and when an interrupt is detected. A low level output is derived to the control circuit 34.

The control circuit 34 also receives a channel selection signal from a selection circuit 35 realized by an up / down switch or the like. The control circuit 34 uses the interrupt detection circuit 33.
When the output from is at a high level, the selection circuit 35
A channel selection signal representing the desired channel of the passenger selected in (3) is derived to the channel separation circuit 32. On the other hand, when the output from the interrupt detection circuit 33 is low level, the control circuit 34 should select the first channel to the channel separation circuit 32 regardless of the selection output from the selection circuit 35. A channel selection signal indicating that is output.

That is, for example, when the four-channel acoustic signal sources T1 to T4 are provided as described above, the channel selection signal input from the selection circuit 35 to the channel separation circuit 32 can be 2 bits. The specific configuration of the control circuit 34 in this case is shown in FIG.

That is, the control circuit 34 comprises an AND gate 41 and an OR gate 42. AN
The upper bit of the channel selection signal from the selection circuit 35 is given to one input of the D gate 41, and the OR gate 4
The lower bit of the channel selection signal from the selection circuit 35 is applied to one of the two inputs. The other input of the AND gate 41 is given the output from the interrupt detection circuit 33, and the other input of the OR gate 42 is inverted and inputted to the output of the interrupt detection circuit 33. . A
The high-order bit and the low-order bit of the channel selection signal are output from the ND gate 41 and the OR gate 42, respectively, and are input to the channel separation circuit 32.

Therefore, when the interrupt detection circuit 33 determines that the identification signal is transmitted, a low level output is derived from the interrupt detection circuit 33, and in response to this, the AND gate 41. Outputs a low level output regardless of the channel selection signal from the selection circuit 35, while the OR gate 42 outputs a high level output regardless of the channel selection signal from the selection circuit 35. In this way, the channel separation circuit 32 can recognize that the channel to be selected is the first channel.

When the identification signal is not detected by the interrupt detection circuit 33 and a high level output is being derived, the other input of the AND gate 41 becomes high level, and the other input of the OR gate 42. The input becomes low level, and the channel selection signal from the selection circuit 35 is output to the channel separation circuit 32 as it is.

The channel separation circuit 32 extracts a sound signal or a sound signal of a channel corresponding to the channel selection signal input as described above, and the sound signal or the sound signal is converted into an analog sound by the digital / analog converter 36. After being converted into a signal and further amplified by the power amplifier 37, it is given to the headphone 40 through the jack 38 and the plug 39 to be sonicated.

As described above, in the data transmission device 21 according to the present invention, when performing n-channel music broadcasting using the acoustic signal sources T1 to Tn, priority voice such as guide broadcasting picked up by the microphone T0. Signal the first
Of the remaining acoustic signal sources T2 to Tn and the interrupt signal. It is multiplexed with an identification signal indicating the presence or absence and transmitted. On the other hand, on the receiver 24 side, in extracting only the acoustic signal of the desired channel, the presence or absence of an interrupt is judged from the identification signal, and when an interrupt is detected, the channel to be selected is switched to the first channel. , Play the audio signal.

Therefore, the passengers in each seat can reliably listen to the guide broadcast or the like regardless of which channel the music is listened to. Therefore, even if the number of channels n increases, it is not necessary to increase the number of switching circuits S unnecessarily, and it is possible to efficiently cope with the increase in the number of channels.

Note that, for example, the number of channels of the acoustic signal source n
Is 8, the channel selection signal output from the selection circuit 35 is 3 bits, and in this case, the control circuit 3
In the gate of No. 4, the upper bits and the middle bits are composed of AND gates, and only the lower bits are composed of OR gates. Similarly, as the number of bits increases, only the least significant bit is composed of an OR gate, and the gates of the remaining bits are composed of AND gates. Alternatively, the audio signal may be interrupted in the nth channel.

FIG. 4 is a waveform diagram for explaining a data transmission method according to another embodiment of the present invention.
Are similar to the above-described FIGS. 2A to 2C, and corresponding parts are designated by the same reference numerals. In this embodiment, in the data signal shown in FIG. 4B, the least significant bit (LSB) of the data D1 of the first channel is deleted and the identification data D0 is inserted instead.

When the left and right components of the acoustic signal are composed of 16 bits as described above, the dynamic range thereof is 1.76 + 6.02 × 16 = 98 (dB). On the other hand, as described above, When the least significant bit is deleted, the total number of bits becomes 15 bits, so the dynamic range in that case is 1.76 + 6.02 × 15 = 92.
(DB). However, in the broadcasting device 22 as described above, the analog / digital converters AD1 to AD are used.
n, digital / analog converter 36 and power amplifier 3
The dynamic range of analog circuits such as 7 is 80
Since it is about (dB), even if the data number of the acoustic signal is reduced by 1 bit as described above, there is almost no problem in hearing. In this way, the identification signal can be transmitted without impairing the sound quality.

[0040]

As described above, according to the present invention, the data signal such as the acoustic signal is time-division multiplexed in the transmission means and serially transmitted, and the data signal of an arbitrary channel is extracted in the reception means. In order to transmit the interrupt data signal that should be extracted with priority over the data signal,
Switching means is provided in association with a predetermined data signal source, and when the interrupt data signal is to be transmitted, this switching means is switched so that the interrupt data signal is transmitted to the receiving means in time division, and When receiving the identification signal indicating that the interrupt data signal is being transmitted, the receiving means switches to select the predetermined channel regardless of the selected channel and is multiplexed and transmitted. Since the received interrupt data signal is extracted, it is possible to reliably extract the interrupt data signal only by providing the switching means only on the predetermined channel even if the receiving means selects an arbitrary channel. . Therefore, an increase in the number of channels can be efficiently dealt with without the number of switching means increasing unnecessarily.

Preferably, the identification signal indicating that the interrupt data signal is transmitted is transmitted instead of the least significant bit of the data signal of the predetermined channel, so that it is transmitted with 16 bits or 14 bits, for example. Audio signals, etc., are practical problems, that is, when the data signals are the audio signals, the influence of narrowing the dynamic range is minimized and the increase in the number of data to be transmitted is suppressed. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a broadcasting device 22 including a data transmission device 21 according to an embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining an operation of the broadcasting device 22 according to an embodiment of the present invention.

3 is a block diagram showing a specific configuration of a control circuit 34 in the receiver 24 of the data transmission device 21. FIG.

FIG. 4 is a waveform diagram for explaining the operation of another embodiment of the present invention.

FIG. 5 is a block diagram showing an electrical configuration of a broadcasting device 2 including a typical prior art data transmission device 1.

[Explanation of symbols]

 21 data transmission device 22 broadcasting device 23 transmitter 24 receiver 25 transmission line 26 multiplexing circuit 28 encoder 30 switching control circuit 31 decoder 32 channel separation circuit 33 interrupt detection circuit 34 control circuit 35 selection circuit 40 headphone T0 microphone T1 to Tn Acoustic signal source S selector switch

Claims (2)

[Claims] 1. A data signal from a data signal source of a plurality of channels is time-division multiplexed in a transmitting means, serially transmitted via a transmission line, and a receiving means outputs a data signal of a channel selected by a selecting means. In the data transmission device configured to extract, an interrupt data signal source that generates an interrupt data signal prioritizing each of the data signals, is interposed between a data signal source of a predetermined channel and the transmitting means, and Switching means for giving priority to the interrupt data signal from the interrupt data signal source to the transmitting means with respect to the data signal, and controlling the switching means while transmitting the interrupt data signal to the transmitting means. And an identification signal source for multiplexing and transmitting an identification signal indicating that the selection signal is provided when the identification signal is received. A data transmission device, comprising: a control unit that causes the reception unit to select the predetermined channel and extract the interrupt data signal regardless of the selection output from the. 2. The data transmission device according to claim 1, wherein the identification signal is transmitted in place of the least significant bit of the data signal of the predetermined channel.