JP2012151750A - Amplifier for community reception system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use an amplifier for community reception system, in which TDA or TBA is selected.SOLUTION: A community reception signal supplied from an input terminal 2 is amplified by first amplification means 8, and the signal is supplied to one branching unit 26. An output signal of the one branching unit 26 is supplied to an output terminal 30, a branching output signal of the one branching unit 26 is supplied to branching/distribution switching means 32, and the output signals of the means 32 are distributed to branching terminals 50, 52, 54 and 56. The branching/distribution switching means 32 includes: first switching means 58 making a branching output signal of the one branching unit 26 to an amplification state where the signal is amplified and outputted or a passing state where the branching output signal of the branching unit is made to pass as it is; and an amplifier 67 amplifying the output signal of the first switching means 58 and supplying the signals to the branching terminals 50, 52, 54 and 56.

Description

  The present invention relates to an amplifier used in a joint reception system, and more particularly to an amplifier that can be used as either a trunk branch amplifier (hereinafter referred to as TBA) or a trunk distribution amplifier (hereinafter referred to as TDA).

  An amplifier for a joint reception system having functions of both TDA and TBA is disclosed in Patent Document 1. In the technique of Patent Document 1, a television broadcast signal supplied from an input terminal is amplified by a first amplifier, and the amplified output is supplied to a single branching device. The output of one branching device is supplied to the output terminal, and the branching output of one branching device is amplified by the second amplifier and then supplied to another one branching device. The output of the other one branching device is attenuated by the variable attenuator, then divided into two by the two distributors as the low distortion branch output, and supplied to the two branch terminals. The branch output of the other one branching device is amplified by a third amplifier, and the amplified output is divided into two by another two distributors as a high gain branch output and supplied to the other two branch terminals. The low distortion branch output is output as the TDA DA output, and the high gain branch output is output as the TBA BA output.

Utility Model Registration No. 2605935

  According to the technology of Patent Document 1, one common reception system amplifier can be operated simultaneously as TBA and TDA. However, it is rare that one amplifier needs to be used as TBA and TDA. Often used individually as TDA. By the way, compared with TBA, TDA is used less frequently in a joint reception system, and if TDA is manufactured independently, the manufacturing cost becomes high. The basic configurations of TDA and TBA are common in that the output of the trunk amplifier is branched by a branching device, and the branch output is distributed to a plurality of branch terminals by a distributor. The TDA needs to enable the branch output of each branch terminal to have a signal quality substantially equivalent to the output of the trunk line system and to be able to output the 1/2 span of the trunk line system output, whereas the TBA Therefore, it is necessary to make the branch output high so that it can be distributed directly to the subscribers of the joint reception system via tap-off.

  An object of the present invention is to provide an amplifier for a joint reception system that can be used as a selected one of TDA and TBA.

  An amplifier for a joint reception system of one embodiment of the present invention has an input terminal to which a joint reception signal is supplied. The first amplification means amplifies the joint reception signal supplied from this input terminal. The output signal of the first amplifying means is supplied to the branching means. The output signal of this branching means is supplied to the output terminal. This output terminal is a so-called trunk line output terminal. The branch output signal of the branch means is supplied to the branch / distribution switching means. The output signals of the branch / distribution switching means are each distributed to a plurality of branch terminals. Distribution means can be used for this distribution. The branch / distribution switching means includes first switching means for either an amplification state in which the branch output signal of the branch means is amplified and output or a passage state in which the branch output signal of the branch means is passed as it is. Yes. The output signal of the first switching means is amplified by the second amplifying means and supplied to each branch terminal.

  In the common reception system amplifier thus configured, when the first switching means of the branch / distribution switching means is switched to the amplification state, the branch output from the branching means is amplified by the first switching means. Then, it is also amplified by the second amplifying means and supplied to each branch terminal. Therefore, the output of each branch terminal is high output. Accordingly, a BA output is generated at each branch terminal by the branch / distribution switching means, and this common reception system amplifier can be used as a TBA. Further, when the first switching means of the branch / distribution switching means is switched to the passing state, the branch output from the branch means is amplified only by the second amplification means and supplied to each branch terminal. . Since amplification is performed only by the second amplification means, the output of each branch terminal is less distorted. Accordingly, a DA output is generated at each branch terminal by the branch / distribution switching means, and this common reception system amplifier can be used as a TDA.

  The branch / distribution switching means is a second switching means for switching between a passing state in which the output signal of the second amplifying means is passed as it is and an attenuation state in which the output signal of the second amplifying means is attenuated. Can be provided. As described above, the TDA branch output is desirably set lower than the main line output. Therefore, when using this common reception system amplifier as the TDA, the output of the branch terminal is lowered by setting the second switching means to the attenuation state.

  Further, in the case where a frequency adjusting means for giving a tilt characteristic to the television broadcast signal is provided between the input terminal and the branching means, the second switching means has the tilt characteristic in the attenuation state. The reverse tilt characteristic can be reversed. In the amplifier for the joint reception system, a frequency adjusting means is provided in order to give a tilt characteristic to the output, but it is desirable that the TDA branch output has a flat frequency characteristic, and it is necessary to have a reverse tilt characteristic. is there. Therefore, when the output of the branch terminal is lowered, the reverse switching characteristic is given by the second switching means.

  As described above, according to the present invention, one common reception system amplifier can be used as one selected from TBA and TDA.

It is a block diagram of the amplifier for joint reception systems of a 1st embodiment of the present invention. It is a figure which shows the frequency characteristic of the common reception system amplifier of FIG. It is a block diagram which shows the use condition as TDA of the amplifier for joint reception systems of FIG. It is a block diagram which shows the use condition as TBA of the amplifier for joint reception systems of FIG.

  The common reception system amplifier 1 according to one embodiment of the present invention has an input terminal 2 as shown in FIG. For example, a joint reception signal of 70 to 770 MHz is supplied to the input terminal 2 via the trunk line of the joint reception system. The joint reception signal supplied to the input terminal 2 is supplied to the first amplifying means 8 through the filter means, for example, the high-pass filter 4 and the pseudo line network (BON) 6. The high-pass filter 4 is for removing unnecessary signal components included in the joint reception signal. In the pseudo-line network 6, the length of the transmission line for transmitting the joint reception signal to the input terminal 2 is different from the predetermined length, and the level of the joint reception signal supplied to the input terminal 2 is different from the prescribed input level. In this case, the input level of the first amplifying means is matched with the specified input level.

  Since the joint reception signal supplied to the first amplifying unit 8 has a flat frequency characteristic in a band of 70 to 770 MHz, a frequency adjusting unit, for example, an equalizer (EQ) 10 provides a tilt characteristic to the joint reception signal. I have it. As a result, the level of the output of the equalizer 10 is higher at 770 MHz than at 70 MHz. The output of the equalizer 10 is amplified by two-stage amplifiers 12 and 14. The output of the amplifier 14 at the subsequent stage is level-adjusted by the gain controller 16, further provided with a tilt characteristic by the equalizer 18, and supplied to the amplifier 20. The output of the amplifier 20 is supplied to a single branching device 22, and the branch output is supplied to an automatic gain control circuit (AGC) 24. The automatic gain control circuit 24 adjusts the gain of the gain controller 16, and the output of the amplifier 20 is set to a predetermined level.

  The output of the one branching unit 22, that is, the output of the first amplifying unit 8 is supplied to a branching unit, for example, one branching unit 26. The output of the one branching unit 26 is supplied to an output terminal, for example, a main line output terminal 30 after unnecessary signal components are removed by a filter means, for example, a high-pass filter 28.

  The branch output of the one branching unit 26 is supplied to a branch / distribution switching means (BA / DA switching means) 32. The output of the branch / distribution switching means 32 is divided into two by a distribution means, for example, a two distributor 34. Each distribution output of the two distributor 34 is divided into two by the two distributors 36 and 38, respectively. The distribution outputs of the two distributors 36 and 38 are supplied to the branch terminals 50, 52, 54, and 56 after unnecessary signal components are removed by filter means, for example, high-pass filters 42, 44, 46, and 48, respectively. Is done.

  The branch / distribution switching means 32 has first switching means 58 to which the branch output of the one branching unit 26 is supplied. In the first switching means 58, an amplifier 60 and a passage (PASS) 62 are connected in parallel. The switch 64 selects either the input side of the amplifier 60 or the input side of the passage 62 and supplies the branch output of the one branching device 26. The switch 66 selects and outputs either the output of the amplifier 60 or the passage 62.

  The output of the amplifier 60 or the passage 62 selected by the switch 66, that is, the output of the first switching means 58 is amplified by the second amplifying means, for example, the amplifier 67, and supplied to the second switching means 68.

  In the second switching means 68, a passage 70 and an attenuation means or a frequency adjusting means for giving a reverse tilt, for example, an equalizer 72 are connected in parallel. The switch 74 selects one of the input side of the passage 70 and the input side of the equalizer 72, and supplies the output amplified by the amplifier 60 to the selected one. Further, the switch 76 selects either the output side of the passage 70 or the output side of the equalizer 72 and supplies it to the two distributor 34.

  When the joint reception amplifier 1 configured as described above is used as TDA, the switches 64 and 66 are switched so that the passage 62 is selected in the first switching means 58, and the second switching means 68 is switched. The switches 74 and 76 are switched so that the passage 70 is selected. As a result, the branch output of the single branching unit 26 is amplified by the amplifier 67 through the passage 62. Here, the gain of the amplifier 67 is obtained by dividing the level of the main line output (TA) generated at the main line output terminal 30 and the output of the amplifier 67 as it is by the two distributors 34, 36, and 38. The branch outputs (DA ′) generated at 52, 54 and 56 are set to be substantially the same (see FIG. 2).

  In the conventional TDA, the DA output has a flat frequency characteristic in the frequency band of 70 MHz to 770 MHz, and from the final stage of the trunk amplifier so that the output becomes 1/2 span of the TA output as described above. In order to branch the signal and provide a half tilt characteristic, an equalizer for attenuating the high frequency of the branch signal was provided, and the output of the equalizer was amplified (in FIG. 1, the branch output of the one branch device 26 is half-turned). This was supplied to an equalizer having a tilt characteristic, and the output of the equalizer was amplified by an amplifier 67 and supplied to the two distributor 34). However, in this configuration, the noise figure of the DA output is deteriorated, and the noise figure is several dB lower than that of the TA output.

  On the other hand, in the configuration described above, since the branch output of the one branching device 26 is amplified by the amplifier 67 without using an equalizer, the noise figure of DA is not deteriorated. However, at the branch terminals 50, 52, 54, and 56, as described above, a DA 'output having substantially the same level as TA is generated. Therefore, as shown in FIG. 3, when a branch amplifier 78 is connected to each branch terminal 50, 52, 54, 56, these branch amplifiers 78 are designed to be connected to a TDA having a conventional branch output level. Therefore, these branch amplifiers 78 are over-input. In order to eliminate this excessive input, it is necessary to replace the pseudo-line network provided in these branch amplifiers 78. However, the amount of attenuation of such a pseudo-line network is large, so that it is difficult to install in the branch amplifier 78, and even if it can be installed, the characteristics of the branch amplifier 78 are likely to deteriorate.

  Therefore, in the common receiving amplifier 1, the output of the amplifier 67 is not directly supplied to the two distributors 34, but the output of the amplifier 67 is passed through the equalizer 72 in the second switching means 68, so that the output is 70 to 770 MHz. And the attenuation at a high frequency is increased and supplied to the distributor 34. As a result, the branch output at each branch terminal 50, 52, 54, and 56 has a flat frequency characteristic at 70 to 770 MHz as indicated by DA in FIG. Become. Instead of the equalizer 72, a pseudo line network can be used.

  When the common reception amplifier 1 is used as a TBA, the switches 64 and 66 are switched so that the amplifier 60 is selected in the first switching means 58, and the passage 70 is selected in the second switching means 68. Thus, the switches 74 and 76 are switched. As a result, the branch output of the single branching unit 26 is amplified by the two stages of the amplifiers 60 and 67. As a result, each branch terminal 50, 52, 54, 56 has a branch output having a level greater than TA, as indicated by BA in FIG. Therefore, as shown in FIG. 4, a common reception signal can be supplied to each branch terminal 50, 52, 54, 56 via a tap-off 82 to a television receiver (not shown) in each home.

  In the above embodiment, the first switching unit 58 is configured to switch the amplifier 60 and the passage 62 by the switches 64 and 66. However, the switches 64 and 66 are removed, and the amplifier 60 and the passage are plugged in. The second switching means 68 can also be configured such that only one of them is installed, and the switches 74 and 76 are removed, and the passage 70 and the equalizer 73 are plugged in. It is possible to configure so that only one of them is installed. In the above embodiment, the four branch terminals 50, 52, 54, and 56 are provided. However, the present invention is not limited to this, and the number of branch terminals is arbitrary as long as it is plural. The number of In the above embodiment, the first amplifying means 8 includes the amplifiers 12, 14, 20, the gain controller 16, the automatic gain control circuit 24, and the equalizers 10, 18, but is not limited to this configuration. Various configurations can be used as long as they can amplify the joint reception signal to a predetermined level. For example, only one of the equalizers 10 and 18 can be used, and the gain controller 16 and the automatic gain control circuit 24 can be removed to form a fixed gain amplifier.

DESCRIPTION OF SYMBOLS 1 Common reception amplifier 2 Input terminal 8 1st amplification means 26 1 branching device 32 Branching / distribution switching means 50 52 54 56 Branching terminal 58 1st switching means 67 Amplifier (2nd amplification means)
68 Second switching means

Claims (3)

An input terminal to which a joint reception signal is supplied;
First amplification means for amplifying the joint reception signal supplied from the input terminal;
Branching means to which the output signal of the first amplifying means is supplied;
An output terminal to which an output signal of this branching means is supplied;
A branch / distribution switching means to which a branch output signal of the branch means is supplied;
A plurality of branch terminals to which the output signals of the branch / distribution switching means are respectively distributed,
The branch / distribution switching means comprises:
A first switching means that is either in an amplified state for amplifying and outputting a branch output signal of the branch means or a passing state for allowing the branch output signal of the branch means to pass through;
Amplifying the output signal of the first switching means and supplying the second amplifying means to the branch terminals;
A common reception system amplifier.   2. The amplifier for a joint reception system according to claim 1, wherein said branching / distribution switching means includes a passing state in which the output signal of said second amplifying means is passed as it is, and attenuation for attenuating the output signal of said second amplifying means. An amplifier for a joint reception system having second switching means for switching to any of the states. The amplifier for a joint reception system according to claim 2, wherein a frequency adjusting means for giving a tilt characteristic to the television broadcast signal is provided between the input terminal and the branching means, and the second switching means is An amplifier for a joint reception system having a reverse tilt characteristic opposite to the tilt characteristic in an attenuation state.

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