JPS5856542A - Wire broadcasting system - Google Patents

Abstract

PURPOSE:To receive a two-frequency signal with a receiver for 1-frequency reception, by converting the 1st broadcasting wave for a plurality of areas and the 2nd broadcasting wave for a specific area in the areas into the same frequency signal. CONSTITUTION:In a wire broadcasting using carrier waves, a signal of frequency fA of a broadcast 1 of (a) for all areas passes through a BPF 21 of a converter 2, and is branched at a branching filter 23 and led to synthesizers 24 and 25. To the synthesizer 24, a signal of frequency fB of a broadcast 200 of (b) for a specific area A applied via branching filters 20 and 26 and the signal of the fA or fB is applied to a frequency converter 22, where the frequencies are converted as fC=f0-fA=fB-f0 by using a local frequency f0 and the signals of the fA and fC are synthesized at a synthesizer 25 and the result is transmitted to the area A via wires. In the area A, the signal of fC is branched at a branching filter 201 and the signal is received at a receiver receiving the frequency fC. The signal of fA is broadcast to other areas through a BPF31 of a converter 3. Thus, the broadcast of fA and fB can be received in the specific area A at the receiver of the same frequency fC.

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, in a cable broadcasting facility that utilizes a carrier wave and uses a nine-wire broadcasting system carrier wave, the broadcast of IIl is broadcast to a large number of areas, and the broadcast of t42 is broadcast to only a specific area among them. One possible method for broadcasting is to use different frequencies a'.

This method requires listeners in a specific area to select the program they want to receive on their 16 receivers. If it is an announcement broadcast from I1 Group V B, it is necessary to select and receive each broadcast if there is one, and the method of automatically selecting it requires an expensive receiver. There is a drawback that.

On the other hand, an example of a method in which the transmitting side selects one is to stop broadcasting when Party A is broadcasting, and only one of Party A and Party B is required to broadcast. In this case, the broadcast frequencies of Party A and Party B can be the same, but in this case Party B's broadcasts will also be broadcast to other areas.

In this case, Party A is broadcasting an announcement aimed at the entire area,
If Party B is an announcement broadcast aimed at a specific area, if there is a difference in the wave number t between Party A and Party B, all of Party A's frequencies for Party B's broadcast to the I#I designated area will be It is necessary to convert to the frequency of the area, or to demodulate the content of Party A's announcement broadcast and re-fX it and broadcast it again in the same way as Party B's announcement broadcast.

Also, in any case, the lines used for broadcasting equipment are generally directional.

With the assumption that signals will be inserted upstream, except in the case of very short lines, the locations of relays, etc. are determined, and these operations ( I-In short, it would actually be necessary to install a line or use another frequency band for transmission in the reverse direction.

This invention has been developed to eliminate the above-mentioned conventional drawbacks, and by converting the carrier waves of the Wkl and second broadcast waves into broadcast waves of the same frequency, a simple system configuration can be used for both A and B. One object of the present invention is to provide a cable broadcasting system in which broadcasts from two points can be received by a receiver with a single receiving frequency.

Hereinafter, embodiments of the cable broadcasting system of the present invention will be described based on the drawings. FIG. 1 is a system diagram showing a simplified configuration of one embodiment, and FIG. 2 shows the configuration of frequencies applied to the present invention.

In Fig. 1, J is the transmission point where all of A's broadcasts occur, and now if the broadcasts from A to P cover the entire area, the carrier wave (frequency f, ) sent out from A will change. I! fA bandpass filter 211 splitter 23 in the 8 unit 2,
The transmission field is transmitted to the bandpass filter J1 of the converter 3 via the combiner 25, the branching device 26, and the branching devices 20, 201 of the service area group B.

These converters 2 and 3 are installed upstream of the % foot area of the transmission line) and have the same configuration.
I will be describing the entire structure of . In this converter 2, the splitters 23 and 26 are connected to a combiner 24, and the combiner 24 is connected to a frequency converter 22. This frequency converter 221 splitter 23 is connected to the combiner 25
M: 1 combiner 25 connects via branch 2# to Converter 3 (
The bandpass filter 31 of D f is folded.

The carrier wave (frequency f, ) branches from the broadcasting point 200 of O.
a20) 1) From the branch 201, the frequency fc<fc
=f0-f, =fl-io) are sent. The signal resulting from the reverse coupling of this branch 2# is transmitted to the branch 201.
The signal is transmitted to the next-stage converter 3, but is blocked by the loss of the splitter 20 and the bandpass filter 31 of the converter 3, and the amount converted by the frequency converter of the converter 30 becomes extremely small.

Next, the operation of the v1m broadcast system of the present invention will be explained. The first broadcast wave that has passed through the bandpass filter 21 of the t converter 2 is branched by a splitter 2J and guided to a combiner 24.

10,000, the splitter 26 is installed to split the signal of the opposite flow to the signal of f, and its branched output is applied to the other end of the combiner 24. The synthesizer 24 converts the signals f, t, or fl from the transmission point 200 to the frequency converter 2.
j, and a signal with a frequency component shown in the m2 diagram is generated.

Here f. is the four-cal frequency of frequency converter 22. Now, here f. -fA-f, determine the local frequency such that -fo, that is, f. t-f□ and! If the intermediate value of , is selected, a signal of the same frequency (assumed to be IC) is obtained for both the input of f and the input of f. This signal is separated by a filter at the output of the frequency converter 22, combined with the signal fA in the combiner 25, and transmitted. This signal is transmitted to the converter 3 via the splitter 26, 2θ, 201t.

However, as described above, the ac signal is cut off in the converter 3 and only the fA signal is applied to the next stage. Converter 3 also operates in the same manner as converter 2. The section between these converters 2 and 3 is Party B's service area A. For example, if the receiver installed at the terminal of branch 201 receives FC (No. 1), broadcasts of Party A or Party B can be received.

Here, considering the return of fc inside the converter 2, the splitter 23.16 is sufficiently reduced by reverse coupling, but due to its characteristics, the line splitter 2J has a bandpass of f, , f, You can also add filters and check safety.

There is also a method of using a filter/rectifier in one synthesizer to reduce insertion loss. Of course, it is also possible to quantify the configuration of the splitter 23% combiner 24.15 and the splitter 25 while being aware of some loss.

Note that as a modification of the above embodiment, there may be a method in which the frequency obtained by fc is not changed as is, but is further converted and transmitted.These are common methods, and their explanation will be omitted.

As described above, in the cable broadcasting system of the present invention, in cable broadcasting equipment that uses carrier waves, the first and second broadcast waves are transmitted at the same frequency by frequency conversion.

Signals of two frequencies can be received by a receiver having the same reception frequency. Along with this, by setting on a simple one frequency array, one place is for the whole area, and one place is for a specific area (2
It becomes possible to construct a broadcasting system with unique characteristics from place to place.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the 411 configuration of an embodiment of the cable broadcasting system of the present invention, and FIG. 2 is a frequency distribution diagram applied to the same cable broadcasting system. 1・I20... Transmission point, 2.3... Converter, 21°31... Bandpass filter, 20, 23 I J 6
, 201... Turnout, 24, 25... Combined hX device,
A: Party B's service area.

Claims (1)

[Claims] Targets multiple areas! In a cable broadcasting system in which a first broadcast wave using a carrier wave of @1 and a broadcast wave of W42 using a second carrier wave targeting a specific area within the area are broadcast via the same transmission path, The broadcast waves of Wi2 are frequency-converted using the same CAL frequency so that they have the same frequency, and the broadcast waves are transmitted to 5! A cable broadcasting system that takes value as a percent image.