JPH05122177A - Method of multiplex transmission - Google Patents

Abstract

PURPOSE:To transmit a digital signal through a broadcasting analog line by modulating a digital signal to an analog signal, dividing the analog signal into frequency bands different from the frequency band of a sound signal, multiplexing the frequency-divided analog signal with the sound signal to send the multiplexed signal, and on the receiving side, separating the received signal into the analog signal and the sound signal, and demodulating the analog signal. CONSTITUTION:On the transmitting side 1, a digital signal including a receiving side specification signal obtained from a computer terminal 1b is modulated to an analog signal and the frequency band of the analog signal is limited to a band different from the frequency band of a sound signal. A sound signal from a microphone (a) is also band-limited to a band different from that band and both the signals are multiplexed and outputted to a broadcasting analog line 2. The sound signal receiving side 3 extracts the sound signal and outputs the sound signal from a speaker or the like and a sign board 4a and a CRT 4b on the receiving side extract and demodulate the modulated digital signal, and after judging the receiving side specification signal, display the demodulated data. Thus the digital signal can be transmitted through an existing line without newly preparing an exclusive line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplexing transmission method for transmitting data to be displayed on a display such as an electronic display board or a computer display through a broadcasting analog line of an existing broadcasting facility.

[0002]

2. Description of the Related Art Conventionally, when a plurality of indicators such as electronic signboards are installed in a building or factory, data such as characters and figures displayed on these indicators are digitized and converted into digital signals. Although it is transmitted, it has been common to newly install a dedicated line (digital line) for digital signal transmission in order to transmit such digital signals.

[0003]

However, laying a new digital line requires enormous cost, and the laying work also takes time and labor. The present invention has been made to solve the above problems, and an object thereof is also to use a broadcasting analog line of an existing broadcasting facility normally laid in a building or factory as a data transmission line to a display unit. The purpose of the present invention is to realize a multiplex transmission method which can reduce the cost and labor required for laying a digital line.

[0004]

In order to solve the above-mentioned problems, in the multiplex transmission method of the present invention, a digital signal is input at the transmitting side together with a voice signal, the digital signal is modulated into an analog signal, and the modulation is performed. The multiplexed analog signal and the audio signal are multiplexed by dividing them into bands of different frequencies, and the multiplexed signal is output to the analog line for broadcasting and transmitted to the audio signal receiving side and the digital signal receiving side, The voice signal receiving side extracts the voice signal from the multiplexed signal through the first filter and outputs the voice signal, and the digital signal receiving side outputs the voice signal from the multiplexed signal through the second filter. The modulated analog signal is extracted, and the modulated analog signal is demodulated into a digital signal and output.

At the transmitting side, a signal for designating the digital signal receiving side to be output is inserted into the digital signal, and at the digital signal receiving side, the signal for designating itself is included in the demodulated digital signal. The digital signal may be output only when it is recognized.

[0006]

According to the multiplex transmission method of the present invention, the input side digital signal is first modulated into an analog signal on the transmitting side, and further divided into a frequency band different from that of the voice signal. By multiplexing with, the data converted into digital signals can also be transmitted through the analog line for broadcasting.

On the audio signal receiving side, the first filter extracts only the audio signal from the multiplexed signal transmitted through the analog broadcasting line and outputs it.

On the other hand, on the digital signal receiving side, only the analog signal modulated from the multiplexed signal is extracted by the second filter, and the extracted analog signal is demodulated again into a digital signal before being output.

In addition, a signal for designating the digital signal receiving side to which the digital signal is to be output is inserted in the digital signal input at the transmitting side, and the digital signal receiving side designates itself in the demodulated digital signal. By configuring such that the digital signal is output only when the signal is recognized, it becomes possible to output the digital signal from the desired digital signal receiving side when there are a plurality of digital signal receiving sides.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the multiplex transmission method of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of the multiplex transmission method of the present embodiment, FIG. 2 is an explanatory diagram of a transmitting side, and FIG. 3 is an explanatory diagram of a voice signal receiving side and a digital signal receiving side.

According to the multiplex transmission method of this embodiment, as shown in FIG. 1, a voice signal is input from a microphone 1a and a digital signal is input from a computer terminal 1b. The digital signal is modulated into an analog signal and then multiplexed with the voice signal. A transmitting side 1, a broadcasting analog line 2 for outputting a multiplexed signal, an audio signal receiving side 3 including a speaker for extracting and outputting an audio signal, an electronic bulletin board 4a for outputting a digital signal, It is composed of a digital signal receiving side 4 composed of a CRT 4b.

As shown in FIG. 2, the transmitting side 1 is provided with a voice signal input section 5 into which a voice signal is input and a digital signal input section 6 from which a digital signal is input.

Information to be transmitted to the digital signal receiving side 4 is converted into a digital signal and input from the digital signal input section 6. At this time, the digital signal receiving side 4
When there are a plurality of addresses, for example, an address such as 01 is assigned to the electronic bulletin board 4a in FIG. 1 and an address such as 02 is assigned to the CRT 4b in advance, and the address for specifying the digital signal receiving side 4 that should receive the digital signal is also digital. Signal and input at the same time.

The digital signal input from the digital signal input section 6 is converted into an analog signal by the modulator 7.

The frequency of the input voice signal and the modulated analog signal (hereinafter referred to as the modulated analog signal) are limited by the frequency control unit 8 so that the frequency bands do not overlap. In this case, it is sufficient to understand the contents of the broadcast in the factory premises broadcasting, etc., and it is not necessary to identify the broadcaster. Therefore, for example, the frequency band of the audio signal to be transmitted is limited to approximately 100 Hz to 2 KHz. ,on the other hand,
The frequency band of the modulated analog signal is 10 KHz or more so as not to overlap with the frequency of the audio signal. In order to avoid duplication of the frequency of the audio signal and the modulated analog signal, for example, when an audio signal having a frequency higher than 5 KHz and a modulated analog signal having a frequency lower than 5 KHz are input, the frequency control unit 8 cuts them. It may be configured to do so. A low pass filter or a high pass filter may be used for the frequency control unit 8.

The audio signal and the modulated analog signal which have passed through the frequency control section 8 are multiplexed by the mixer 9 into a multiplexed signal which is output to the broadcast analog line 2 and transmitted to the receiving side.

As for the transmitted multiplexed signal, as shown in FIG. 3, only the audio signal is extracted by the low-pass filter (for example, a cutoff frequency of 5 kHz) 10 as the first filter on the audio signal receiving side 3 and the speaker is extracted. The sound is output through the output device 11 such as.

On the digital signal receiving side 4, the second
High-pass filter (for example, cutoff frequency 5
KHz) 12 to extract only the modulated analog signal from the multiplexed signal.

The demodulator 1 extracts the modulated analog signal.
It is converted by 3 into the original digital signal.

The demodulated digital signal is input to the signal determiner 14. The signal determiner 14 determines whether or not the digital signal input to the digital signal receiving side 4 includes a signal (hereinafter, referred to as a designated signal) related to the address for designating itself, and designates the signal. Only when the signal is included, it is output from the output device 15 such as an electronic bulletin board.

It is desirable to interpose an amplifier 16 in the middle of the line in order to prevent the power from being attenuated when the analog line 2 for broadcasting has a long distance.

As described above, in the present embodiment, the modulator 7 modulates a digital signal into an analog signal, and the frequency controller 8 divides the frequency band of the voice signal and the frequency band of the modulated analog signal so that they do not overlap each other. Since they are multiplexed and multiplexed, digital data can be transmitted through existing broadcasting analog lines without laying a dedicated line.

On the audio signal receiving side 3, the low-pass filter 10 can extract only the necessary audio signal from the multiplexed signal and output it. On the digital signal receiving side as well, only the required modulated analog signal can be extracted from the multiplexed signal by the high-pass filter 12, and the demodulator 13 demodulates the modulated analog signal to output a digital signal.

Further, there are a plurality of digital signal receiving sides 4
For example, 01 for the electronic display board 4a and 0 for the CRT 4b.
Addresses such as 2 are assigned in advance, and the address designating the digital signal receiving side 4 which should receive the digital signal is also converted into a digital signal and input. On the other hand, the digital signal receiving side 4 is demodulated by the signal judging device 14. Since the digital signal is output only when the designated signal is included in the digital signal, the transmitted digital signal can be output to the desired digital signal receiving side. Thus, for example, a plurality of digital signals are simultaneously input, one of the digital signals is output and displayed on the electronic display board 4a, and the other digital signal is CR.
Selective transmission of digital signals is possible, such as output display on T4b.

[0025]

According to the multiplex transmission method of the present invention, a digital signal is modulated into an analog signal, and the modulated analog signal and voice signal are divided into bands of different frequencies to be multiplexed for broadcasting. The signal output to the analog line, the audio signal receiving side extracts and outputs the audio signal from the signal multiplexed through the first filter, and the digital signal receiving side outputs the signal multiplexed through the second filter. Since the modulated analog signal is extracted from this signal and this modulated analog signal is demodulated into a digital signal and output, there is no need to newly install a dedicated line for digital signal transmission, and existing broadcast Digital signals can be transmitted using analog lines.

On the transmitting side, a signal for designating the digital signal receiving side to be output at the time of inputting the digital signal is inserted, and on the digital signal receiving side, the signal for designating itself is recognized in the demodulated digital signal. Only in this case, since the digital signal is output, the transmitted digital signal can be output to the desired digital signal receiving side.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a multiplex transmission method according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a transmitting side of a multiplex transmission method showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a voice signal receiving side and a digital signal receiving side of a multiplex transmission method according to an embodiment of the present invention.

[Explanation of symbols]

 1 transmitting side 2 analog line for broadcasting 3 audio signal receiving side 4 digital signal receiving side 5 audio signal input section 6 digital signal input section 7 modulator 8 frequency control section 9 mixer 10 low-pass filter 11 output unit (audio signal) 12 high Band filter 13 demodulator 14 signal determiner 15 output device (digital signal) 16 amplifier

Claims (2)

[Claims] 1. A transmission side inputs a digital signal together with a voice signal, modulates the digital signal into an analog signal, and multiplexes the modulated analog signal and the voice signal by dividing them into bands of different frequencies. , The multiplexed signal is output to the analog line for broadcasting and transmitted to the audio signal receiving side and the digital signal receiving side, and the audio signal receiving side passes the first signal through the multiplexed signal to the audio signal. The signal is extracted and output, and the digital signal receiving side extracts the modulated analog signal from the multiplexed signal through the second filter and demodulates the modulated analog signal into a digital signal. A multiplexed transmission method characterized in that the data is output as 2. The transmitting side inserts a signal for designating a digital signal receiving side to be output in the digital signal, and the digital signal receiving side inserts the signal for designating itself in the demodulated digital signal. The multiplexed transmission method according to claim 1, wherein the digital signal is output only when it is recognized.