JPH0744546B2 - Data transmission method and apparatus using broadcasting wiring - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a data transmission method and apparatus using broadcast wiring.

(Prior art) For example, in order to broadcast music, voice, etc. on a specific premises, after amplifying audio signals from a tape deck or microphone with a PA amplifier, multiple PAs are sent via PA lines (broadcast wiring). There is known a PA system in which information is transmitted to speakers and broadcast from those speakers.

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

(Problems to be solved by the invention) Thus, it is uneconomical to provide the PA line and the data line separately, and if the PA line is already provided, this
It is extremely economical to use PA lines for data transmission. However, when the transmission code is superposed on the PA line, the transmission code and the voice 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. In order to prevent this, it can be considered that the transmission code is band-limited to cut the low frequency band. However, due to this band limitation, interference between transmission codes may increase.

The present invention has been made in view of the above, and its purpose is to:
To provide a method and an apparatus capable of performing proper data transmission without widening a required band while suppressing interference between a transmission code and a voice signal or between transmission codes even if a broadcasting wiring is used for transmitting data. Especially.

(Means for Solving the Problems) In the data transmission method using the broadcasting wiring of the present invention, in the transmitter of the data transmission / reception device, the data signal to be transmitted is converted into a DC balanced code by the converter, and the transmission filter is used. After removing the voice band signal component by the above, it is sent to the wiring as a superimposed signal superimposed on the audio signal in the broadcasting wiring, and the superimposition transmitted via the wiring in the receiver of another data transceiver. A voice filter signal component is removed from a signal by a reception filter to extract a DC balanced code, and an inverse converter is used to reproduce the original data signal from the DC balanced code.

A data transmission device using a broadcasting wiring of the present invention includes a broadcasting wiring for transmitting an audio signal, a plurality of data transmission / reception devices connected to the wiring, and transmitting and receiving the data signal as a superposed signal superposed on the audio signal via the wiring. And a data transmission / reception device of
The data transmission / reception device includes a converter that converts the data signal into a DC balanced code, a transmitter that has a transmission filter that removes a voice band signal component from the DC balanced code, and a signal transmitted via the wiring. A receiver having a receiving filter for removing a voice band signal component from the superposed signal and outputting a DC balanced code, and an inverse converter for inversely converting the DC balanced code into an original data signal. Composed.

(Operation) The converter in the transmitter of the data transmitter / receiver converts the data signal to be transmitted into a DC balanced code. A voice band signal component is removed from the DC balanced code by a transmission filter. The output from this filter is sent to the broadcasting wiring and is superimposed on the audio signal in the wiring to become a superimposed signal.

This superimposed signal is transmitted to the receiver of another data transmitting / receiving device through the broadcasting wiring. The reception filter of the receiver removes the voice band signal component from the superimposed signal,
The DC balance code is retrieved. The original data signal is reproduced from the DC balanced code by the inverse converter.

(Embodiment) FIG. 1 is a block diagram of an embodiment of the present invention. In the figure, reference numeral 1 denotes a PA amplifier. In this amplifier 1, a signal from a tape deck or a microphone (not shown) is amplified and transmitted to a PA speaker (SPK) 3, 3, ... Via a PA line 2. . As a result, music and voice are broadcast from those speakers 3, 3. .. and (data) communication terminals 6, 6, .. are connected to the PA line 2 via superimposing circuits 4, 4 ,.

FIG. 2 is a circuit diagram showing details of the superposition circuit 4, the transmission / reception circuit 5 and the communication terminal 6 of FIG. As can be seen from FIG. 2, the digital data signal from the (data) communication terminal 6 is applied to the code converter 5a of the transmission / reception circuit 5 from the data output terminal 6a. In the code converter 5a, the digital data signal is converted into a DC balanced code and added to the HPF 5b. In this HPF 5b, the signal obtained by removing the voice frequency component from the DC balanced code is the transformer 4a of the superimposing circuit 4 in the next stage.
Added to. 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 voice signal.

On the other hand, the superimposed signal from the other communication terminal 6 is applied to the transformer 4b of the superimposing circuit 4 via the PA line 2, and the transformer 4b
Is added to the HPF 5c of the transmission / reception circuit 5 via. The HPF5c removes the voice band signal from the superposed signal to obtain a DC balanced code. This DC balanced code is sent to the code inverse conversion unit 5d and inversely converted to reproduce the original digital data. This digital data is added to the communication terminal 6 from the data input terminal 6b of the communication terminal 6 in the next stage.

In this way, using the PA line 2 as a transmission line, the communication terminals 6, 6, ...
Data is transmitted between them.

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

The DC unbalanced signals include RZ code and NRZ code. In such a DC unbalanced code, the power spectrum is concentrated in the low frequency region including DC. Therefore, such a DC unbalanced signal is not suitable for the signal processing such as shown in FIG. 2 which passes the HPFs 5b and 5c at the time of transmission and reception.

On the other hand, the DC balanced code is bipolar (AM
I) There are codes and bifuse codes. When such a DC balanced code is used, the utilization efficiency of information is reduced and the required band is increased, but the low frequency region component is reduced.
Therefore, such a DC unbalanced signal can be used for signal processing as shown in FIG.

FIGS. 3 (a) and 3 (b) show the spectrum level and waveform of the NRZ code (DC balanced code) and AMI code (DC unbalanced signal) with respect to the normalized frequency. It can be seen from FIG. 9A that the NRZ code is closer to the low frequency band and the AMI code has less low frequency components.

FIG. 4 shows the spectrum level of the AMI code (DC unbalanced code). When such an AMI code is used in FIG. 2, it can be seen that the component (voice band) cut by the HPFs 5b and 5c is only a part as shown in the figure and has almost no influence on information transmission. .

(Effect of the Invention) According to the present invention, it is possible to properly transmit data by using the wiring in the broadcasting facility as a data transmission line. Therefore, it is not necessary to separately lay the wiring for the broadcasting equipment and the wiring for the data transmission, which is economical. In particular, if there is existing broadcasting equipment wiring, it is more effective to use it.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a circuit diagram showing details of a part thereof, FIG. 3 is a diagram and a waveform diagram showing spectrum levels of NRZ code and AMI code, and FIG. The figure is a diagram showing the spectrum level of the AMI code and the cut component due to the HPF. 2 ... PA line, 4 ... superposition circuit, 5 ... transmission / reception circuit, 6 ...
… Communication terminal, 5a …… Code converter, 5b, 5c …… HPF, 5d ……
Sign reverse converter.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuaki Kumagai, 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Kanagawa Japan Victor Company of Japan, Ltd. (72) Kazuhiro Osugi, 3-12 Moriya-cho, Kanagawa-ku, Yokohama Address within Victor Company of Japan, Ltd. (56) Reference JP-A-57-207460 (JP, A) JP-A-57-180245 (JP, A)

Claims (2)

[Claims] 1. A transmitter of a data transmitter / receiver converts a data signal to be transmitted into a DC balanced code by a converter, removes a voice band signal component by a transmission filter, and then converts it into a voice signal in a wiring for broadcasting. The superimposed signal is sent to the wiring as a superimposed signal, and the receiver of another data transmitter / receiver removes the voice band signal component from the superimposed signal sent through the wiring by the reception filter to obtain a DC balanced code. A data transmission method using broadcasting wiring, which is characterized in that the original data signal is reproduced from the DC balanced code by an inverse converter. 2. A broadcasting wire for transmitting an audio signal, and a plurality of data transmission / reception devices which are connected to the wiring and which transmit and receive a data signal as a superposed signal superposed on the audio signal via the wiring. The data transmitter / receiver is transmitted via the wiring, and a transmitter having a converter for converting the data signal into a DC balanced code and a transmission filter for removing a voice band signal component from the DC balanced code. A receiver having a reception filter for removing a voice band signal component from the superposed signal and outputting a DC balanced code, and an inverse converter for inversely converting the DC balanced code into an original data signal. A data transmission device using broadcasting wiring.