JPS6262087B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a branching device used in wired communication equipment that allows for example UHF and VHF band television signals to coexist with mutual communication signals such as carrier intercom signals.

It is conceivable to share common television reception equipment as a communication line such as a carrier-type intercom. For example, using the wiring diagram of wired communication equipment shown in FIG. 1, a television receiver 3 is connected to branch terminals 2a and 2c of a branch 2, and
A transport type intercom 4 is connected to each of the terminals 2d. In such a wiring state, the receiving antenna 1
The TV signal received at the branch terminal 2 of the branch 2
The signals are supplied to the television receivers 3 connected to terminals a and 2c, respectively. On the other hand, communication signals between the carrier intercoms go back and forth between the branch terminals 2b and 2d of the branching device 2. However, as is well known, the branching device used for joint TV reception is designed to prevent spurious signals leaking from the local oscillator of the TV receiver from flowing back from the branch terminal and causing beat interference to other TV receivers. The branching characteristics have directionality. To explain this using Figure 2, the signal branched from the input terminal 5 to the branch terminal 7 will be attenuated by 10 dB in the case of a splitter with a coupling loss of 10 dB and a reverse coupling loss of 30 dB, Since the signal passing from the terminal 6 to the branch terminal 7 is attenuated by 30 dB, each bidirectional signal going back and forth between the branch terminals 2b and 2d of the branch 2 has an attenuation of 10 dB when the branch in the above example is used as the branch 2. and 30dB added
40 dB, which means that the signal from the other party's carrier intercom is reduced by a factor of 100, which poses the problem of significantly reducing the clarity of communication.

The present invention is suitable for use when common television reception equipment is shared as a communication line of a specific frequency band such as a carrier intercom, and only signals of a specific frequency have bidirectionality, and television signals have directional properties. The object of the present invention is to provide a turnout having the following features.

FIG. 3 shows the first embodiment of the branching device of the present invention, in which 8 is an input terminal, 9 is an output terminal, and 10 is an input terminal.
is a branch terminal, 11 is a transformer with a turns ratio of 1:n used as the first branch element,
L1 is a primary winding, L2 is a secondary winding, and these windings are sufficiently coupled to each other and wound around a cylindrical ferrite core, for example, to form a closed magnetic path. The a side of the primary winding L1 is connected to the input terminal 8, the b side is connected to the output terminal 9, and the
The c side of the next winding L2 is connected to the branch terminal 10, and the d
side is connected to the h side of the specific frequency bidirectional generation element 16. 12 is an autotransformer used as the second branch element, L3 is the primary winding, L4 is the
are the secondary windings, and they are wound in a sufficiently connected state to form a closed magnetic path around, for example, a cylindrical ferrite core, and the primary winding L3
The winding end side of the secondary winding L4 is connected to the winding start side of the secondary winding L4, and the intermediate tap f is taken out.
The e side of 4 is connected to the k side of the resistance element 13, and the other end j side is connected to the input terminal 8. The intermediate tap f is connected to the branch terminal 10. The g side of the primary winding L3 is grounded in terms of high frequency. Furthermore, resistance element 13
The resistor 14 is used to create the directionality of the branch, and the well-known resistor 14 shown in FIG. 4 is used, and as shown in FIG. A capacitor 15 having an extremely small reactance at high frequencies may be connected in series for the purpose of blocking high frequencies and passing only high frequencies. Reference numeral 16 denotes a specific frequency bidirectional generation element which is designed to give the splitter bidirectional characteristics at a specific frequency. For example, a parallel resonant circuit composed of a capacitor 17 and a coil 18 is used, and one end For example, if the i side is grounded, the other end h side is connected to the d side of the secondary winding L2 of the transformer 11. still,
As shown in FIG. 7, the specific frequency bidirectionality generating element 16 includes a parallel circuit of a capacitor 17 and a coil 18, and a high-frequency generator whose purpose is to block direct current or alternating current at the commercial power frequency and pass only high-frequency waves. A capacitor 19 having an extremely small reactance may be connected in series with the capacitor 19. FIG. 8 shows a second embodiment of the branching device of the present invention, in which one end of the specific frequency bidirectionality generating element 16 is connected to the c side of the secondary winding of the first transformer 11, for example, to the h side. and the other end i side is branch terminal 1.
0, and the d side is grounded in terms of high frequency, and the rest is the same as that described in the configuration of FIG.

Next, for the branch circuit having the above configuration, for example, the one shown in FIG. The constants of each part when the signal frequency is 20MHz will be explained.

The transformer 11 uses a cylindrical ferrite core, and has a primary winding L1 and a secondary winding L2 connected to it.
A cylindrical ferrite core is used for the autotransformer 12, and a primary winding L3 and a secondary winding L4 are wound thereon at a turns ratio of 2:1. The resistance value of the resistance element 13 is 250 to 300Ω, the capacitor 17 of the specific frequency bidirectional generation element 16 is 20PF, and the coil 18 is 3μH.

FIG. 9 shows a characteristic diagram of the branch circuit configured with the above numerical values, where A is the insertion loss and the output terminal 9 when a signal is input from the input terminal 8.
B is the coupling loss at the branch terminal 10 when the signal is input from the input terminal 8, C is the reverse coupling loss at the branch terminal when the signal is input from the output terminal 9. 10 shows the amount of signal loss. As shown in the figure, coupling loss occurs in the VHF band from 90 to 222MHz in the television frequency band.
10dB, reverse coupling loss 30-35dB, insertion loss 1dB, 470
In the UHF band ~770MHz, coupling loss is 11 dB, reverse coupling loss is 20 to 25 dB, insertion loss is 1.5 dB, and coupling loss is at 20 MHz, which is the frequency used by carrier intercoms.
Characteristics of 11 dB, reverse coupling loss of 12 dB, and insertion loss of 1.2 dB were obtained. If two of the above branches are connected in series and a carrier type intercom is connected to each branch terminal, the signal attenuation between the intercoms will be 23 dB, which is the sum of the reverse coupling loss of 12 dB and the coupling loss of 11 dB. The signal from the standard intercom only needs to be attenuated by a factor of about 14.

FIG. 10 shows a circuit in which a well-known two-way splitter 20 is connected to the branch terminal 10 of the turnout shown in FIG. shows.

Figure 11 is a wiring diagram of a branch common reception facility using the branch circuit shown in Figure 10, with two branch terminals 2
One branch terminal 21 of 1 and 22 is connected to the antenna terminal of the television receiver 3, and the other branch terminal 22 is connected to the transmitting/receiving terminal of the transport type intercom 4, respectively, via a feed line 23.

As described above, in the present invention, TV broadcast signals have directional properties, and signals in arbitrarily selected and determined frequency bands such as carrier intercoms have bidirectional properties. This prevents spurious leakage from the TV receiver's local oscillator from flowing backwards through the branch terminal and into the later stage of the receiving equipment, and also prevents negative effects on the image quality of the TV receiver connected to the branch terminal of the front branch. Moreover, losses in mutual communication lines such as carrier intercoms are significantly reduced, so communication with extremely high clarity is possible, and important communication contents can be accurately conveyed. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram of wired communication equipment, Fig. 2 is a diagram showing the symbol mark of a switch, Fig. 3 is a diagram showing the first embodiment of the switch of the present invention, and Fig. 4 is a resistance element. FIG. 5 is a diagram showing an example of a different resistance element; FIG. 6 is a diagram showing an example of a specific frequency bidirectional generating element; FIG. 7 is a diagram showing a different specific frequency bidirectional generating element; FIG. The figure shows a second embodiment of the turnout of the present invention, FIG. 9 is a characteristic diagram of the first turnout shown in FIG. 3, and FIG. 10 is a characteristic diagram of the first turnout shown in FIG. FIG. 11 is a diagram illustrating the state of use of the community reception equipment using the branch shown in FIG. 10. 8... Input terminal, 9... Output terminal, 10... Branch terminal, 11... Transformer, 12... Auto transformer, 13... Resistance element, 16... Specific frequency bidirectional generation element.

Claims (1)

[Claims] 1 Connect one end of the primary winding of the transformer used as the first branch element to the input terminal, the other end to the output terminal, and connect one end of the secondary winding to the specific frequency bidirectional generation element. one end of the specific frequency bidirectional generation element and the other end of the secondary winding of the transformer are connected to a branch terminal, the other is grounded, and the second branch element In an autotransformer used as A switch which is grounded, the other end of the secondary winding being connected to one end of a resistance element for creating directionality of the switch, and the other end of the resistance element being connected to an input terminal.