JPS6037839A - Two-way amplifier with automatic gain controller - Google Patents

Abstract

PURPOSE:To control two signals to a prescribed value with one pilot signal by controlling the signal which is attenuated in case of the pilot signal is transmitted through a coaxial cable, to a preliminarily expected value. CONSTITUTION:When the pilot signal attenuation in the 1st coaxial cable 10 is changed due to the temperature change or the like, an output level of the 1st amplifier section 16 and an attenuation control voltage are changed. The attenuation of a voltage variable attenuater 22 is controlled in response to the change so that the output level of the 1st amplifier section 16 is coincident with an output signal level of a two-way amplifier of the pre-stage connected via the 1st coaxial cable 10. When the attenuation of the 1st coaxial cable 10 is changed similarly, the attenuation of an incoming signal is also changed. Thus, the outgoing signal level and the incoming signal level always attains to a prescribed value even if the temperature change or the like exists.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides two-way joint viewing in which, for example, signals are transmitted from the head amplifier side to each terminal side in a joint viewing device, and signals are transmitted from each terminal side to the head amplifier side. This invention relates to a falling amplifier (C) used in an apparatus, and particularly relates to one equipped with an automatic gain controller.

Conventionally, when automatically controlling the gain of each bidirectional amplifier in the above-mentioned two-way communal viewing and viewing apparatus, a signal (hereinafter referred to as a downstream signal) is supplied from the head amplifier side to the terminal side.

) (hereinafter referred to as the downlink pilot signal) and a signal supplied from the terminal side to the head amplifier side (hereinafter referred to as the upstream signal).
Two pilot signals were sometimes used: /rlJ (a pilot signal for controlling 'rJ (hereinafter referred to as a two-high lot signal)).

For example, Fig. 1 shows an example in which there is one main line, and the head amplifier 1 has a built-in downlink pilot signal generator, and the main line branch amplifier at the terminal of the main line: ', VCj: re-pilot signal generator 3. I have set it up. 4.4... is the main line amplifier, and these and the main line branch amplifier? The gain is controlled according to the uplink pilot signal and the downlink pilot signal.

In Figure 2, the main line is divided into two, and in this case, each terminal of each main line receives an upstream pilot signal and a bow generator 3.
'f: Provided.

The main line is divided into four parts, and in this case, there is also an uplink pilot signal generator 3 at the terminal of each main line.
has been established.

In these conventional systems, the lower sivirot signal generation 2: ÷
Two types of pilot signal generators, an uplink pilot signal generator and an uplink pilot signal generator, are required. In particular, the ones shown in FIGS. 2 and 3 require a plurality of uplink pilot signal generators 3, which is not only uneconomical but also Breakdowns were also more likely to occur. Moreover, the second
Since the upstream pilot signal is mixed in the 2-divider 5 in the figure and in the branch amplifier 6 in FIG. 3, it was not possible to control the gain using the head-up 1 and the 2-way signal V.

In order to solve the above problems, it is an object of the present invention to provide a bidirectional amplifier with an automatic gain controller that can control the gains of both downlink and uplink signals using only a VCl pilot signal. , Therefore, this invention
A first amplification section with a built-in attenuator that amplifies the first signal and pilot signal received from the first coaxial cable and supplies the amplified signals to the second coaxial cable is different from the first signal received from the second coaxial cable. a second amplifying section with a built-in attenuator that amplifies a second signal of the same frequency and supplies the second signal to the coaxial cable; and an attenuation control section that supplies the attenuator in the second amplification section 3B, and the attenuation control section of the first amplification section is configured to compensate for the attenuation of the first signal in the first coaxial cable based on the attenuation control signal. , and the attenuator of the second amplifying section is configured to compensate for the attenuation of the second signal in the first coaxial cable based on the attenuation control signal 5.
, with this configuration, the first
The amplifying section can compensate the value of the already attenuated signal transmitted through the first coaxial cable to a constant value and supply the same to the second coaxial cable. In other words, the value of the first signal supplied to the second coaxial cable (C) is a constant value.
The amplifying section adjusts the value of the second signal to a value that anticipates in advance the amount by which the second signal will be attenuated by the pilot signal when it is transmitted through the entire first coaxial cable. As a result, the final value of the second signal transmitted through the first coaxial cable always remains constant. Therefore, it is possible to control each of the first and second signals to predetermined values by using only one pilot signal. Therefore, it is not only economical but also reduces the occurrence of failures. Furthermore, even if there are a plurality of trunk lines as shown in FIGS. 2 and 3, the gains can be automatically controlled in all the trunk amplifiers without any special processing.

Hereinafter, this invention will be explained in detail based on one embodiment shown in FIG. In the same figure, 10 is the first coaxial cable, which connects the bidirectional amplifier in the previous stage to, for example, 70 to 2!5 degrees.
It transmits a down signal of MH2 frequency and a pilot signal of 246 MHz. The lower multi-signal and the pilot signal are sent to the first amplifying section 1 via a terminal 12 and a filter 14.
6. The first amplifier section 16 includes two amplifier circuits 1
It is equipped with a VC voltage variable attenuator 22 between 8.20 and amplifies the supplied down signal and pilot signal,
The second coaxial cable 28 is connected via the filter 24 and the terminal 26.
supply to.

The second coaxial cable 28 transmits, for example, an upstream signal of 10 to 50 MHz from a bidirectional amplifier at the subsequent stage.

This upstream signal passes through the filter 24 to the second amplification section;
supplied to The second amplification section 30 includes one amplification circuit 32
Output side 1! ζIt is equipped with a lightning pressure variable attenuator 34,
The upstream signal is amplified and supplied to the first coaxial cable 10 via the filter 14 and the terminal 12.

IfCi between the output side of the first amplifier section 16 and the filter 24
, j1 branch 36 is provided, and this 1 branch 3 (
'l vc, a part of the output signal of the first amplifying section 16 is branched. A pilot signal is extracted from this branched output signal of the first amplifying section 16 by a hat-pass filter 38 and is supplied to an AGCi circuit 40 . AGC circuit 4o
1ri.

An attenuation control voltage is generated based on the extracted pilot signal and supplied to the voltage variable attenuator 22.34.

and 9, the attenuation in the voltage variable attenuator 22.34 changes, and the gains of the first and third amplification sections 16.30 change.

Here, if the amount of attenuation at 246 MHz Vc, which is the frequency of the pilot signal in the first coaxial cable lO, changes due to temperature changes, etc., the first amplifying section 16
The 24.6 MHz output level and attenuation control voltage are varied. 246 Mn according to changes in this attenuation control voltage
The variable attenuator 22 is set so that the output level of the first amplifying section 16 of the 2 signal matches the output l of the 246 MHz output signal of the previous stage bidirectional amplifier connected via the first coaxial cable 〕○. The constant of variable attenuator 22 is selected to control the attenuation at .

Similarly, the first coaxial cable 1 in the 246 MHz IC
If the amount of attenuation at 0 changes due to temperature changes, the amount of attenuation at 50MHz, which is the highest frequency of the upstream signal, will also change to 246MHz.
Although it is less than in the case of H2, it changes. Therefore, the 50MHz,z input level of the bidirectional amplifier in the previous stage also changes.

In order to compensate for this change, the attenuation control voltage is changed according to the change in the amount of attenuation at 246 MHz K, so that the input level of the human-powered L/bevel second amplifier 30 at 50 MHzvc of the bidirectional amplifier in the previous stage is adjusted to match the input level of the second amplifier 30. Attenuation of the attenuator 34 can be controlled (variable attenuator 22
Select a constant.

Therefore, the level of the downlink signal supplied to the second coaxial cable 28 is always a constant value even if there is a change in temperature, etc.
The upper signal supplied to the preceding bidirectional amplifier via the coaxial cable 10 also remains at a constant value (lζ) even if there is a change in temperature or the like.

Note that this bidirectional amplifier can be used as the main amplifier shown in FIGS. 1 to 7Ii to FIG. Accordingly, it can be used as the trunk branch amplifier 2 shown in FIGS. 2 and 3 or the trunk distribution amplifier 6 shown in FIG.

In the above embodiment, the first amplification section] 6 is lightning, and the pressure variable attenuator 2
2 is provided between the two amplifier circuits 18 and 20 (l), and f?c is the input side of the amplifier circuit 18, and f?c is the output of the amplifier circuit 20 (ll).
It may be provided in the second amplification section 3o, or may be configured in the same manner as the second amplification section 3o. Further, an electric power variable attenuator 34 is provided on the output side of the second amplifying section 30 and the amplifying circuit 32.
It may be provided on the input side of the amplifier, or configurations 1 to 3 may be used similarly to the first amplifier]6.

[Brief explanation of the drawing]

Figure 2 is a block diagram of a conventional two-way joint viewing and viewing device.
Figure 3 is a block diagram of another conventional two-way joint viewing and viewing device.
This figure is a block diagram of yet another conventional two-way communal viewing device, and FIG. 4 is a block diagram of one embodiment of a two-way amplifier with an automatic gain flit controller according to the present invention. DESCRIPTION OF SYMBOLS 10... First coaxial cable, 6... First amplifying section, 22... Variable attenuator with built-in first amplifying section, 28.
...Second coaxial cable, 30...Second amplification section, 34...Variable attenuator with built-in second amplification section, 36.3
8.40...Attenuation control circuit. Patent applicant DIEX Antenna Co., Ltd. Agent Satoshi Shimizu Haga 2 people

Claims (1)

[Claims] (1) What is the first amplification section with a built-in attenuator that amplifies the first signal and pilot signal received from the first coaxial cable and supplies them to the second coaxial cable, and the first signal received from the second coaxial cable? Amplify the second signal of a different frequency to
a second amplification section with a built-in attenuator that supplies the coaxial cable;
A gate that generates an attenuation control signal based on a pilot signal extracted from an output signal of the amplification section and supplies it to the attenuators in the first and second amplification sections; B is configured to compensate for the attenuation of the first signal in the first coaxial cable based on the attenuation control signal Km, and the attenuator of the second amplification section is configured to compensate for the attenuation of the first signal in the first coaxial cable based on the attenuation control signal Km. A bidirectional amplifier with an automatic gain controller configured to compensate for attenuation of a second signal.