JPH02159144A - Method and device for transmission of data with use of broadcast wiring - Google Patents

Abstract

PURPOSE:To perform the proper transmission of data without increasing a necessary band by converting the data signal to be transmitted into a DC balance code to superpose it on a sound signal for transmission after eliminating the voice band signal component via a transmission filter and therefore suppressing the interference caused between the transmitted code and the sound signal or between the transmitted codes with each other. CONSTITUTION:The digital data signal received from a communication terminal 6 is applied to a code converter 5a of a transmission/reception circuit 5 via a data output terminal 6a and converted into a DC balance code. This code is applied to an HPF 5b where the voice frequency component is eliminated. The signal free from the voice frequency component is applied to a transformer 4a of superposition circuit 4 of the next stage. The signal received from the HPF 5b is transmitted to a PA line 2 via the transformer 4a, and the DC balance code is transmitted to another terminal 6 via the line 2 as a superposition signal superposed on the sound signal. In such a way, the data can be properly transmitted without spreading a necessary band by using a wiring of the broadcast equipment as a data transmission line.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Separation) The present invention relates to a data transmission method and apparatus using broadcast wiring.

(Prior art) For example, in order to broadcast music, audio, etc. to a specific campus, the audio signal from a tape deck or microphone is amplified by a PA amplifier, and then transmitted to multiple PAs via a PA line (broadcast wiring). A PA system is known in which information is transmitted to speakers and broadcast from those speakers.

On the other hand, in order to transmit data between a plurality of communication terminals, a dedicated data line for data transmission was provided in addition to the above-mentioned PA.

(Problem to be Solved by the Invention) In this way, it is uneconomical to provide a PA line and a data line separately, and if a PA line is already provided,
If this PA line is used for data transmission, it is extremely economical. However, when a transmission code is superimposed on a PA line, the transmission code and the audio signal may interfere with each other because the transmission code has a spectrum up to the DC region, although it varies depending on the type. To prevent this, it is conceivable to apply a band limit to the transmission code by cutting the low frequency band.

However, due to this band 1.1 limit, interference between transmission symbols may increase.

The present invention has been made in view of the above, and its purpose is to:
To provide a method and device that can suppress interference between transmission codes and audio signals and between transmission codes, and perform proper data transmission without expanding the required bandwidth, even when broadcasting wiring is used to transmit data. It's about doing.

(Means for Solving the Problems) A data transmission method using broadcasting wiring according to the present invention converts a data signal to be transmitted into a DC balanced code using a converter in a transmitting IJ machine of a data transmitting/receiving device. After the audio band signal component is removed by a filter, it is sent to the wiring as a superimposed signal superimposed on the audio signal in the broadcasting wiring, and the receiver of another data transmitting/receiving device receives the signal sent through the wiring. The receiving filter removes voice band signal components from the superimposed signal to extract a DC balanced code, and an inverse converter reproduces the original data signal from this DC balanced code.

The data transmission device using the broadcast wiring of the present invention has a sound output of 1
The data transmitting/receiving device includes a broadcast wiring for transmitting a signal, and a plurality of data transmitting/receiving devices connected to the wiring and transmitting/receiving a data signal as a superimposed signal superimposed on the audio signal via the wiring. a transmitter having a converter that converts a data signal into a DC balanced code; a transmission filter that removes a voice band signal component from the DC balanced code; The receiver is configured to include a receiving filter that removes signal components and outputs a DC balanced code, and an inverse converter that inversely converts the DC balanced code into the original data signal.

(Operation) The data signal to be transmitted is converted into a DC balanced code by the converter in the transmitter of the data transmitting/receiving device. The voice band signal component is removed from the DC balanced code by a transmission filter. The output from this filter is sent into the broadcast wiring and is superimposed on the audio signal in the wiring to form a superimposed signal.

This superimposed signal is transmitted to receivers of other data transmitting/receiving devices via broadcast wiring. The receiving filter of the receiver removes the voice band signal component from the superimposed signal,
A DC balanced symbol is extracted. The original data signal is regenerated from this DC signal by an inverse converter.

(Example) FIG. 1 is a block diagram of one embodiment of the present invention.

In the figure, 1 is a PA amplifier, and this amplifier 1
Then, the signals from the tape deck and microphone (not shown) are amplified and sent to the PA speaker (SPK) via the PA line 2.
3,3. It can be conveyed to... This causes those speakers 3, 3 . Music and audio will be broadcast from... This PA line 2 has superimposed circuits 4.4. . . via the transmitting/receiving circuits 5, 5 . ... and (data) communication terminals 6, 6.・
... is connected.

FIG. 2 is a circuit diagram showing details of the superimposing circuit 4, the transmitting/receiving circuit 5, and the communication terminal 6 shown in FIG. As can be seen from FIG. 2, the digital data signal from the (data) communication terminal 6 is transmitted from the data output terminal 6a to the code converter 5 of the transmitting/receiving circuit 5.
added to a. In this code converter 5a, the digital data signal is converted into a DC balanced code, and the HPF 5b
added to. In this HPF 5b, a signal obtained by removing the audio frequency component from the DC balanced code is applied to the transformer 4a of the superimposing circuit 4 at the next stage. The signal from the HPF 5b is transmitted to the PA line 2 via the transformer 4a, and is transmitted to another communication terminal 6 via the PA line 2 as a superimposed signal in which the DC balanced code is superimposed on the audio signal.

On the other hand, a superimposed signal from another communication terminal 6 is applied to the transformer 4b of the superimposing circuit 4 via the PA line 2, and is applied to the HPF 5c of the transmitting/receiving circuit 5 via the transformer 4b. The HPF 5c removes the tone band signal from the superimposed signal to obtain a DC balanced code. This DC balanced code is sent to the code inverter 5d and inversely converted to reproduce the original digital data. This digital data is applied to the communication terminal 6 at the next stage from the input terminal 6b of the communication terminal 6.

In this way, communication terminal 6.
Data transmission is performed between 6, .

Next, the reason why the DC balanced code is used in the above embodiment will be explained.

Examples of DC unbalanced and P-balanced codes include RZ codes and NRZ codes. In such a direct current useless quotient code, the cass vector is concentrated in a low frequency region including direct current. Therefore,
Such a DC unbalanced code passes through the HPF 5b during transmission and reception, as shown in FIG. 2 above.

It is not suitable for signal processing that passes through 5c.

On the other hand, as a DC balanced code, bipolar (AM
There are I) codes, bifus codes, etc.

When such a DC balanced code is used, the information utilization efficiency decreases and the required band increases, but the low frequency region component becomes small. Therefore, such a DC signal f'& can be used for signal processing as shown in FIG. 2 above.

FIGS. 3(a) and 3(b) show the spectral levels and waveforms of the NRZ code (DC balanced code) and AMI code (DC unbalanced code) with respect to normalized frequencies. From the same figure (a), the NRZ code is closer to the low frequency range, and the AMI
It can be seen that the code has few low frequency components.

FIG. 4 shows the spectrum level of the AMI code (DC low V-high code). When such an AMI code is used in Fig. 2, the components (voice band) cut by HPFs 5b and 5c are only a small part as shown in the figure, and have almost no effect on information transmission. Recognize.

(Effects of the Invention) According to the present invention, data can be properly transmitted without expanding the required band by using wiring in broadcasting equipment as a data transmission line. Therefore, it is not necessary to separately install wiring for broadcasting equipment and wiring for data transmission, which is economical. In particular, if there is existing wiring for broadcasting equipment, it is more effective to use this.

FIG. 3 is a diagram showing a cut component by HPF and a cut component by HPF.

2... PA line, 4... Superimposition circuit, 5... Transmission/reception circuit, 6... Communication terminal, 5a... Code converter, 5b,
5c... HPF, 5d... Code inverse converter.

Claims (1)

[Claims] 1. In the transmitter of the data transmitting/receiving device, the data signal to be transmitted is converted into a DC balanced code by the converter, the audio band signal component is removed by the transmission filter, and then the data signal in the broadcasting wiring is It is sent to the wiring as a superimposed signal superimposed on the audio signal, and in the receiver of another data transmitting/receiving device, the audio band signal component is removed by a receiving filter from the superimposed signal sent via the wiring, and the signal is converted into a direct current. A data transmission method using broadcasting wiring characterized in that a balanced code is extracted and the original data signal is reproduced from the DC balanced code using an inverse converter. 2. The data transmitting/receiving device comprises a broadcasting wiring for transmitting an audio signal, and a plurality of data transmitting/receiving devices connected to the wiring and transmitting/receiving a data signal as a superimposed signal superimposed on the audio signal via the wiring. a transmitter having a converter that converts the data signal into a DC balanced code, a transmission filter that removes an audio band signal component from the DC balanced code, and the superimposed signal sent via the wiring. Broadcasting characterized by comprising: a receiving filter that removes audio band signal components from a signal and outputs a DC balanced code, and a receiver that has an inverse converter that converts the DC balanced code inversely into the original data signal. Data transmission device using wiring.