JPS6188623A - Wide-range broadcast system using weak radio wave - Google Patents

Abstract

PURPOSE:To improve the flexibility an the efficiency of a wide-range broadcast system by setting the small-scale and inexpensive broadcast equipments at necessary areas in links. CONSTITUTION:A master station 10 is set at a place near the center of its service area, and the TV signals of the broadcast counters produced at a broadcast center 11 undergo the FM modulation through a transmitter 12. Then the weak radio waves are produced through a non-directional antenna 13. The transmitter 12 produces radio waves A and B of two channels of different frequencies which are FM-modulated by the modulation signal of the same broadcast program through the antenna 13. The repeater stations 20 and 30 are set within a service area using the weak radio waves of the station 10. The station 20 receives and demodulates the wave B and then modulates it again to produce the wave A. While the station 30 receives and demodulates the wave A and modulates it again to produce the wave B.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wide area broadcasting system using weak radio waves that can be implemented with small-scale equipment.

(Blue version of the invention) The current previsicon broadcasting network is constructed by a collection of extremely large-scale broadcasting equipment, and can provide good reception over an extremely wide area. This broadcasting network is made possible by high-power transmission equipment and high-quality equipment. It takes.

Self-produced information services centered on local communities and school education in densely populated urban areas over a fairly wide area? If you want to independently broadcast broadcast programs such as I'Silk or other programs that are not covered by traditional television broadcasting networks, it is easy to realize this economically and physically with the current high-power broadcasting system. I can't.

(Purpose of the Invention) The purpose of the invention is, for example, to make it possible to perform television broadcasting over a relatively wide area using weak radio waves using a small power transmitter that is not subject to strong legal regulations. In particular, we want to make sure that each piece of equipment that makes up the system is small and inexpensive, that it can be flexibly adapted to the size of the service area, and that it is easy to implement physically and economically. The aim is to provide a wide area broadcasting system using weak radio waves.

(Structure of the Invention) The system of the present invention that achieves the above object has a micropower transmitter and an omnidirectional transmitting antenna, and has a plurality of channels with different frequency bands that are FM modulated with a modulated signal of the same broadcast program. It has a master station that generates weak radio waves, a directional receiving antenna, a receiver, a micropower transmitter, and a transmitting antenna, and receives and demodulates radio waves from one of the multiple channels, and uses the frequencies of other channels. Again, it is composed of a relay station that generates M-modulated weak radio waves, a plurality of the relay stations are arranged within the service area of the master station, and further the relay stations are arranged within the service area of each relay station. Chain-shaped ribs--characterized by expanding the bis area.

(Embodiment) FIGS. 1 and 2 show a system configuration of an embodiment of the present invention. The master station 10 is installed near the center of the service area to be covered. In the master station 10, the television signal (video signal and audio signal) of the broadcast content produced by the broadcast center 11 is FM-modulated by the transmitter 12, and weak radio waves are generated from the omnidirectional antenna 13. The transmitter 12 has two systems, and generates two channels of weak radio waves with different frequency bands from the antenna 13, which are FM-modulated using modulated signals of the same broadcast program. Here, the two-channel radio waves are referred to as A waves and B waves. It is better that the frequency bands of A wave and B wave are close to each other.

The scale of the transmitter 12 and antenna 13 described above shall satisfy the condition that "the electric field strength of the emitted radio wave is 15 μV/m or less at a distance of 100"n+ from the radio equipment." Under Japan's current Radio Law, it would be possible to open a network without obtaining a license from the Minister of Posts and Telecommunications or the local radio management bureau chief. A plurality of relay stations 20 and 30 are arranged within the service area of the base station 10 using weak radio waves as described above. The relay station 20 receives the B wave, demodulates it, re-modulates it, and generates an A wave radio wave. The relay pole 30 receives the A-wave radio wave, demodulates it, re-modulates it, and generates a B-wave radio wave.

The receiving antenna 21 (31) of the relay station 20 (30) is a directional antenna, and is a transmitting antenna for the radio waves to be received (in the explanation so far, the transmitting antenna 13 of the master station 10).
Set up towards. The B wave (A wave) captured by the directional receiving antenna 21 is received by the receiver 22 (32), amplified and demodulated, and the demodulated signal is sent to the transmitter 23 (33).
).

The transmitter 23 (33) is a low power transmitter similar to the transmitter 12 of the master station 10. The transmitter 23 generates an A wave and transmits l! 1lI33 generates a B wave. Relay station 20.30
The transmitting antennas 24 and 34 are basically omnidirectional antennas. However, it is not necessary to have complete omnidirectionality, but may have appropriate directivity.

The above-mentioned relay stations 20.30 are installed not only in the service area of the master station 10 but also in the relay station 20.30's own service area, and a large number of relay stations 20.30 are installed as shown in FIG. They are combined in a chain so that either the A wave or the B wave can cover the required broadcast area.

Here, only one of the A wave and the B wave needs to reach the target area with a predetermined electric field strength. In other words, the receiver only has to catch and receive either the A wave or the B wave, whichever one can be received better.

In this way, even if each broadcasting facility is extremely small and simple, by extending the chain of service areas in the necessary direction, it is possible to cover a very wide area. In other words, since there is no need to supply radio waves to areas where they are not needed, the service area can be expanded in a narrow line.

In the above embodiment, the master station 10 generates two channels of radio waves, A wave and B wave, but the present invention is not limited to this. 'rM may be formed. In that case, it is easier to prevent radio wave interference. Further, although the above embodiment has been explained as television broadcasting, it is of course possible to use it for other radio wave broadcasting services as well.

(Effects of the Invention) According to the invention described in detail above, extremely small-scale and inexpensive broadcasting equipment can be installed in a chain at the necessary locations to spread radio waves to the necessary areas. The high-efficiency system it supplies enables the realization of a broadcasting system that covers a wide area. Therefore, compared to conventional broadcasting systems using large amounts of power, it becomes possible to realize a wide area broadcasting system much more economically and physically.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a wide area broadcasting system according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a chain of service areas in the same system. 10... Parent station 12...) Transmitter 13... Omnidirectional transmitting antenna 20.30
...Relay station 21.31 ...Directional receiving antenna 22.32
...Receiver 23.33 ...Transmitter 24.34 ...Transmission antenna Patent applicant Tokyo Music Television Co., Ltd.

Claims (1)

[Claims] (1) A master station that has a low power transmitter and an omnidirectional transmitting antenna and generates multiple channels of weak radio waves with different frequency bands that are FM modulated with a modulated signal of the same broadcast program; and a directional receiving antenna. It has a receiver, a low-power transmitter, and a transmitting antenna, receives and demodulates radio waves from one of the plurality of channels, and then re-fs the radio waves at the frequencies of other channels.
A relay station that generates M-modulated weak radio waves; multiple relay stations are placed within the service area of the master station, and further relay stations are placed within the service area of each relay station to form a chain. A wide-area broadcasting system using weak radio waves that expands the service area.