JPH0774559A - Bidirectional amplifier - Google Patents

Abstract

PURPOSE:To provide a bi-directional amplifier for effectively and efficiently using the power consumption of a bidirectional CATV system. CONSTITUTION:In the case of using this bi-directional amplifier unidirectionally, a slide switch 17 is switched, a contact point al is connected to b1 and the contact point c2 and the contact point a2 are separated. Further, the slide switch 16 is switched, the contact point a1 and the contact point b1 are connected and the contact point c2 and the contact point a2 are separated. Thus, a power source is not supplied from a power source part 11 to an up amplifier part 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional amplifier with reduced power consumption, and is particularly suitable for application to a bidirectional CATV.

[0002]

2. Description of the Related Art Broadband transmission lines such as coaxial cables are used for signals over multiple channels to prevent hearing loss in areas where reception is difficult and to provide information through independent broadcasting or connection with a central processing unit (CPU). The two-way CATV (Two-WayC) that can be transmitted and transmitted and the information can also be transmitted from the subscriber terminal.
able television) system is being installed.
The outline of this interactive CATV system will be described with reference to FIG.

In this figure, bidirectional branch trunk line amplifiers 102, 103 and 104 are inserted at predetermined intervals in a trunk line 101 connected to a head end 100. The bidirectional branch main line amplifiers 102 to 104 down-convert the amplified signals to a predetermined level by amplifying a television signal or the like, and branch the bidirectional function to the branch main line 105. It is used for polling to detect whether it has been done. However,
Although only the branch trunk line 105 branched by the bidirectional trunk line amplifier 103 is shown in this figure, a plurality of branch trunk lines are branched from each of the bidirectional branch trunk line amplifiers 102 to 104.

A plurality of branching devices 106 to 109 connected in cascade to the branching main line 105, a bidirectional extension amplifier 110 for compensating the level of a television signal, and the branching device 1 are further provided.
11, 112 are connected. This plurality of branching devices 10
Television signals and the like branched by 6 to 109, 111, and 112 are input to the receivers of the respective subscribers. The downlink amplification section in the bidirectional extension amplifier 110 performs equalization amplification of television signals and the like, and uses the bidirectional function for the status monitor function. The bidirectional trunk line branch amplifier 10
2 to 104 and the bidirectional extension amplifier 110 are supplied with power from a power supply 113 installed in the system. The power from the power supply 113 is transmitted by also using the trunk line 101 and the branch trunk line 105. By separating this power source from the trunk line 101 or the branch trunk line 105, the power is supplied to the amplifiers 102 to 104 and 110. It's being used.

Next, a block diagram of the bidirectional extension amplifier 110 is shown in FIG. In this figure, the first input / output terminal 2
The signal input from 14 is input to the first demultiplexer / mixer 201 via the coupling capacitor C1, demultiplexed by the first demultiplexer / mixer 201, and equalized by the equalizer 202. . The equalized signal is processed by the gain control circuit 203 to be followed by the downstream amplification section 20.
4 is adjusted so that the level output from 4 becomes a predetermined level, and is amplified by the downlink amplification section 204 to obtain the tilt circuit 20.
Applied to the second demultiplexer / mixer 206 via 5. The tilt circuit 205 is a circuit for slightly adjusting the inclination of the frequency characteristic. Then, they are mixed in the second demultiplexer / mixer 206 and output from the second input / output terminal 215 via the coupling capacitor C2.

The upstream signal input from the second input / output terminal 215 is also input to the second demultiplexer / mixer 206 via the coupling capacitor C2, and the second demultiplexer / mixer 206 is also provided. Is equalized and the signal is equalized by the equalizer 207. The equalized signal is adjusted by the gain control circuit 208 so that the level output from the succeeding upstream amplification unit 209 becomes a predetermined level, is amplified by the upstream amplification unit 209, and the tilt of the frequency characteristic is tilted by the tilt circuit 210. After being adjusted, it is applied to the first demultiplexer / mixer 201 and output from the first input / output terminal 214 to the upstream side.

Further, the downstream amplification section 204 and the upstream amplification section 2
The power supplied to 09 is supplied from the power supply unit 211. The power supply unit 211 closes the switch (SW1) 212 when power is supplied from the first input / output terminal 214, and switches (SW2) 213 when power is supplied from the second input / output terminal 215. Is closed, and the transmitted AC voltage is converted into a DC voltage for driving the semiconductor circuits forming the amplifiers 204 and 209 and supplied. The power supply unit 211 is supplied with AC power from the power supply unit 113, as shown in FIG.

[0008]

Bidirectional CA shown in FIG.
In the TV system, the trunk system uses the bidirectional function for polling, but in the bidirectional extension amplifier 110 inserted in the branch trunk system, since there is almost no upstream signal from each subscriber, the bidirectional function is unidirectional. There are many examples of operating facilities. However, since the extension amplifier inserted in the branch trunk system has a bidirectional function, the power consumption of the upstream amplifier is added and the power efficiency of the CATV system deteriorates. There was a problem that was required. In addition, there is a product in which the upstream amplification unit is attachable / detachable in the extension amplifier, but this makes an expensive product because it requires a single unit and pacing. Therefore, an object of the present invention is to provide a bidirectional amplifier for effectively and efficiently operating the power consumption of the bidirectional CATV system.

[0009]

In order to achieve the above object, the present invention provides a branch trunk system by operating a branch trunk system in one direction of downlink or by switching a switch when the level of an upstream signal is strong. The power is not supplied to the upstream amplification section of the bidirectional amplifier inserted in the.

[0010]

According to the present invention, when the branch trunk system is operated in one direction or when the level of the upstream signal is strong, the upstream amplifier does not consume the power source, so that the power consumption can be effectively and efficiently operated. You can For this reason, a new expensive power supply device is not needed, and an increase in cost can be suppressed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a bidirectional extension amplifier of the present invention is shown in FIG. 1 and will be described with reference to this figure. In this figure, a television signal or the like input from the first input / output terminal 14 connected to the branch trunk line is a coupling capacitor C1.
Is input to the first demultiplexer / mixer 1. The signal demultiplexed by the demultiplexer / mixer 1 is equalized by the equalizer 2 and the gain control circuit 3 adjusts the gain so that the level output from the down-amplifier 4 becomes a predetermined level. To be done. The tilt circuit 5 adjusts the slope of the frequency characteristic of the output from the downlink amplification unit 4, and inputs the output to the second demultiplexer / mixer 6. And
The signals are mixed by the second demultiplexer / mixer 6 and output from the second input / output terminal 15 via the coupling capacitor C2.

On the other hand, the upstream signal input from the second input / output terminal 15 is demultiplexed by the demultiplexer / mixer 6 via the coupling capacitor C2, and the second slide switch 17 of the second slide switch 17 via the DC blocking capacitor C4. It is input to the contact point a1. When the movable contact portion of the slide switch 17 is at the position shown in the figure, the contact points a1 and c1 are connected, the contact points c2 and a2 are connected, and the contact points c1 and c2 are connected by a line. Contact point a1
The signal input to is output from the contact a2, the signal is equalized by the equalizer 7 via the DC blocking capacitor C3, and applied to the gain control circuit 8 to adjust the gain. As a result, a signal having a predetermined level is output from the up-amplifier 9, the tilt of the frequency characteristic of the output signal is adjusted by the tilt circuit 10, and the signal is input to the contact a2 of the first slide switch 16.

When the movable contact portion of the slide switch 16 is at the position shown in the figure, the contact point a2 is connected to the contact point c2, the contact point c1 is connected to the contact point a1, and the contact points c1 and c2 are connected by a line. Therefore, the signal input to the contact a2 is output from the contact a1 and input to the first demultiplexer / mixer 1 to be mixed, whereby the first input / output is performed via the coupling capacitor C1. Output from the terminal 14 to the upstream side. Further, the power supply for operating the downstream amplification unit 4 is supplied from the power supply unit 11, and the power supply for operating the upstream amplification unit 9 is supplied from the power supply unit 11 via the choke coil 19 to the contacts c2 and a2 of the slide switch 17. And is also supplied via the choke coil 18. Therefore, when the movable contact portion of the slide switch 17 is at the position shown in the figure, power is being supplied to the up amplification unit 9.

When the movable contact portions of the slide switch 16 and the slide switch 17 are switched to the positions opposite to the illustrated positions, the mixed lines of the first demultiplexer / mixer 1 are connected to the contact b1. Is terminated by the terminating resistor 20-1 and the branching line of the second branching / mixing unit 6 has a contact b.
It is terminated by the terminating resistor 20-2 connected to 1. At this time, the contact c2 of the slide switch 17 is the contact a2.
Therefore, no power is supplied to the upstream amplification unit 9. Note that the capacitor C4 blocks the direct current power supply from being applied to the down amplification unit 4 side, and the capacitor C4
Reference numeral 3 prevents the DC power supply from being applied to the upstream amplification section 9 side. The choke coils 18 and 19 prevent high frequency signals from leaking to the power supply line.

By the way, although the AC power source is supplied to the power source section 11 by the power source, the present invention is not limited to this example, and the AC power source is supplied from the first input / output terminal 14 via the transmission line. Closes the switch (SW1) inserted in the line indicated by the broken line, applies the AC power transmitted to the power supply unit 11, converts it into a DC voltage, and supplies the power to the up amplification unit 9 and the down amplification unit 4. To do so. Further, when the AC power is supplied from the second input / output terminal 15 via the transmission line, the switch (SW) inserted in the line indicated by the broken line
2) 13 may be closed and an AC power supply may be applied to the power supply unit 11 to convert it into a DC voltage to supply power to the up amplification unit 9 and the down amplification unit 4. 1 of the present invention shown in FIG.
According to the embodiment, in the case of a facility that uses the bidirectional extension amplifier inserted in the branch trunk line system in one direction in the bidirectional CATV system, the slide amplifiers 16 and 17 are switched to be consumed by the up amplification unit 9. The power that is consumed can be saved.

The reason for this will be briefly described with an example.
For example, when the power consumption of the bidirectional trunk line branch amplifier inserted in the trunk line system and the power consumption of the bidirectional extension amplifier inserted in the branch trunk line system are respectively 30 VA, two bidirectional trunk lines inserted in the trunk line system are assumed. When power is supplied to the branch amplifier and one bidirectional extension amplifier inserted in the branch trunk line system from one power supply unit with a capacity of 90 VA, the total power consumption of the three amplifiers is 90 VA. However, the total power consumption exceeds 90 VA due to the loss of the power source due to the transmission line. For this reason, another power supply must be installed. However, when power is not supplied to the upstream amplification section of the bidirectional extension amplifier, if the power consumption by this amplifier is 20 VA, the total power consumption can be 90 VA or less, so one power supply unit with a capacity of 90 VA is provided. Power can be supplied from.

Further, since the power supply device has a built-in power supply transformer, it is large in size and heavy in weight, which requires a large space for installation and installation work. This is one of the factors that increase costs. However, according to the present invention, as described above, it is possible to obtain a special effect that there is no need to newly increase the number of power supply devices.

Next, a second embodiment of the bidirectional extension amplifier of the present invention is shown in FIG. The bidirectional extension amplifier shown in this figure
The power consumption is reduced when it is not necessary to strongly amplify the level of the upstream signal. However, the block diagram shown in this figure shows only the upstream amplification section side,
Blocks on the side of the downlink amplifier are the same as those in the block diagram shown in FIG.

In the second embodiment shown in FIG. 2, the signal demultiplexed by the demultiplexer / mixer 6 is a DC blocking capacitor C.
It is input to the contact point a1 of the second slide switch 17 via No. 4. When the movable contact portion of the slide switch 17 is at the position shown in the figure, the contact points a1 and c1 are connected, and the contact points c2 and a2 are connected, and
Since the contact point c1 and the contact point c2 are connected by a line, the signal input to the contact point a1 is output from the contact point a2, the signal is equalized by the equalizer 7 via the DC blocking capacitor C3, and the gain control circuit is obtained. The gain is adjusted by being applied to 8. As a result, a signal having a predetermined level is output from the up-amplifier 9, the tilt of the frequency characteristic of the output signal is adjusted by the tilt circuit 10, and the signal is input to the contact a2 of the first slide switch 16.

When the movable contact portion of the slide switch 16 is at the position shown in the figure, the contact a2 is connected to the contact b2, the contact b1 is connected to the contact a1, and the contact b1 and the contact b2 are connected by a line. Therefore, the signal input to the contact a2 is output from the contact a1 and input to the first demultiplexer / mixer 1. Further, the power supply for operating the downstream amplification unit 4 is supplied from the power supply unit 11, and the power supply for operating the upstream amplification unit 9 is supplied from the power supply unit 11 via the choke coil 19 to the contacts c2 and a2 of the slide switch 17. And is also supplied via the choke coil 18. Therefore, when the movable contact portion of the slide switch 17 is at the position shown in the figure, power is supplied to the up amplification unit 9.

When the level of the upstream signal is strong and the movable contact portions of the slide switch 16 and the slide switch 17 are switched to the positions opposite to the illustrated positions, the demultiplexed line of the second demultiplexer / mixer 6 is Since the contacts a1 and b1 of the slide switch 17 are connected, the DC blocking capacitor C
The signal via 4 is input to the low pass filter (LPF) 21. The output of the LPF 21 is split / branched because the contact c1 and the contact a1 of the slide switch 16 are connected.
It is applied to the mixer 1 and mixed. Further, in this case, since the contact point c2 and the contact point a2 of the slide switch 17 are not connected, no power is supplied to the upstream amplification section 9. The cutoff frequency of the LPF 21 is set to a frequency at which the upstream frequency signal can pass.

In the case of the second embodiment, the bidirectional function is secured even in the branch trunk system, but the power consumption can be reduced.
The same effect as that of the embodiment can be obtained. In addition,
Although the slide switch is used as the switch in the first and second embodiments of the present invention described above, the present invention is not limited to this, and a relay or an electronic switch can be used. In this case, two switches are used. It becomes possible to switch simultaneously by action. Further, in the first embodiment, an upstream signal detector is provided, and when the upstream signal is detected by the upstream signal detector, power is supplied to the upstream amplifier section. In the second embodiment, the upstream signal level is increased. If a detector is provided and the upstream signal level detector detects a low-level upstream signal, power is supplied to the upstream amplification section, and the switch is automatically switched to reduce power consumption. You can

[0023]

Since the bidirectional amplifier of the present invention is configured as described above, the upstream amplifier does not consume power when the branch trunk system is operated in one direction or when the upstream signal level is strong. Power consumption can be operated effectively and efficiently. Therefore, a new expensive power supply device is not needed.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of a bidirectional amplifier according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of the bidirectional amplifier of the present invention.

FIG. 3 is a diagram showing an outline of an interactive CATV system.

FIG. 4 is a block diagram of a conventional bidirectional amplifier.

[Explanation of symbols]

 1,201 1st demultiplexing / mixing device 6,206 2nd demultiplexing / mixing device 2,7,202,207 Equalizer 3,8,203,208 Gain control circuit 4,204 Downstream amplification part 5,10, 205,210 Tilt circuit 9,209 Upstream amplification section 11,2111 Power supply section 12,13,212,213 Switch 14,214 First input / output terminal 15,215 Second input / output terminal 16 First slide switch 17th 2 slide switch 18, 19 choke coil 20-1, 20-2 termination resistor 21 LPF 100 head end 101 main line 102, 103, 104 bidirectional main line branch amplifier 105 branch main line 106-109, 111, 112 branch device 110 both Extension amplifier 113 Power supply

Claims (3)

[Claims] 1. A bidirectional amplifier including a downstream amplification section and an upstream amplification section between a first input / output terminal and a second input / output terminal, wherein a first switch is provided on the output side of the upstream amplification section. At the same time, a second switch is provided on the input side of the upstream amplification unit, the second switch is used to switch whether or not power is supplied to the upstream amplification unit, and the upstream amplification unit is connected to the second input / output terminal. Is connected or not, and whether or not the output side of the upstream amplifier is connected to the first input / output terminal is switched by the first switch. By switching the second switch,
A bidirectional amplifier characterized in that power is supplied to the upstream amplification section. 2. A first demultiplexer / mixer connected to a first input / output terminal, a down amplification unit connected to a line demultiplexed by the first demultiplexer / mixer, and An upstream amplifier connected to a line mixed by the first demultiplexer / mixer via a first switch, a second demultiplexer / mixer connected to a second input / output terminal, The upstream amplification unit connected to the line demultiplexed by the second demultiplexer / mixer via the second switch, and the downlink connected to the line demultiplexed by the second demultiplexer / mixer. An amplifier section, and when the first switch is switched to connect the upstream amplifier section to the mixed line of the first demultiplexer / mixer, the second switch is switched to The upstream amplifier is connected to the line demultiplexed by the second demultiplexer / mixer, and the power source is connected to the upstream amplifier. When connecting the terminator to the mixed line of the first demultiplexer / mixer by switching the first switch, the second switch is switched to the second demultiplexer. / A bidirectional amplifier characterized in that a terminating device is connected to a line demultiplexed by a mixer, and power is not supplied to the upstream amplification section. 3. A first demultiplexer / mixer connected to a first input / output terminal, a down-amplifier connected to a line demultiplexed by the first demultiplexer / mixer, and An upstream amplifier connected to a line mixed by the first demultiplexer / mixer via a first switch, a second demultiplexer / mixer connected to a second input / output terminal, The upstream amplification unit connected to the line demultiplexed by the second demultiplexer / mixer via the second switch, and the downlink connected to the line demultiplexed by the second demultiplexer / mixer. An amplifier section, and when the first switch is switched to connect the upstream amplifier section to the mixed line of the first demultiplexer / mixer, the second switch is switched to The upstream amplifier is connected to the line demultiplexed by the second demultiplexer / mixer, and the power source is connected to the upstream amplifier. When the output terminal of the low pass filter is connected to the mixed line of the first demultiplexer / mixer by switching the first switch, the second switch is switched to the second switch. A bidirectional amplifier characterized in that the input terminal of the low-pass filter is connected to the line demultiplexed by the demultiplexer / mixer and the power is not supplied to the upstream amplification section.