JP3156078B2 - TV receiver amplifier - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a television receiving amplifier, and more particularly, to a television VHF and a television having two types of antennas dedicated to television VHF reception and television UHF reception only. The present invention relates to a television receiving amplifier that can cope with both UHF and all-band antennas.

(Prior Art) This type of amplifier is generally configured by housing an amplifying element in one case, and there are two types: an amplifier mounted on a mast on a roof together with a TV antenna, and a type mounted near a TV receiver. Was.

However, the former type has poor workability because the place where the screen of the television receiver is checked and the place where the gain is adjusted are separated.

On the other hand, the latter type has good workability, but it is attenuated in the process of transmitting radio waves from the antenna to the amplifier, so in areas where the received radio waves are weak, the signal input to the amplification element falls below the practical level. This causes noise on the TV screen.

Therefore, conventionally, as described in JP-A-56-106436, for example, the first amplifier element is provided, and a first amplifier disposed near the antenna and a second amplifier element are provided.
There has been proposed a two-stage amplification type television receiving amplifier including a second amplifier disposed near a television receiver and a variable attenuator provided in series with the second amplification element. .

(Problems to be Solved by the Invention) The two-stage amplification type television receiving amplifier can solve the disadvantages of both types in the one-stage amplification type at once, but has only one input terminal. However, if the TV VHF and TV UHF radio waves are supplemented by separate antennas, a separate mixer must be purchased separately.
If dedicated connection terminals are provided for each, the all-band antenna that covers the television VHF and the television UHF cannot be used.

Therefore, in the present invention, not only two different antennas dedicated to television VHF reception and television UHF reception only,
It is an object of the present invention to provide a two-stage amplification type television receiving amplifier which can also support an all-band antenna covering a television VHF and a television UHF.

(Means for Solving the Problems) The present invention is a television receiver amplifier developed to achieve the above object, and has a first amplifier element having a first amplifier element and arranged near an antenna. The first amplifier and the second
A second element having an amplifying element and disposed near the television receiver
And a variable attenuator provided in series with the second amplifying element, wherein the first amplifying element includes a first switch via a changeover switch. A first VHF amplification element connected to the input terminal and connected to the second input terminal via the changeover switch and the low-pass filter; and a first VHF amplification element connected to the second input terminal via the high-pass filter. And an input terminal connected to the first VHF amplification element can be selected from the first input terminal and the second input terminal by the changeover switch.

(Operation) In the case of using two types of antennas, one dedicated to TV VHF reception and the other dedicated to TV UHF reception, an antenna is connected to each input terminal so that the second input terminal and the two amplifying elements are connected. This can be handled by operating the changeover switch.

When only one all-band antenna is used, the antenna is connected to the second input terminal, and switching is performed so that the second input terminal and the second amplification element are connected via a high-pass filter. It can be handled by operating the switch.

Embodiment First, a basic structure and principle of a television receiving amplifier will be described with reference to a type having a built-in mixer.

1 and 2 exemplify a television receiving system using a television receiving amplifier, wherein 1 denotes an antenna for a television VHF, and 2 denotes an antenna for a television UHF.

Reference numeral 3 denotes a first amplifying unit, the case of which is attached to a mast 10 on a roof A, for example, as shown in FIG.

Reference numeral 4 denotes a second amplifying unit, which is on the television receiver 5 in the room B,
Or it is used by placing it near.

Reference numeral 6 denotes a transmission line connecting the television 1 VHF antenna 1 and the first amplifier 3, and 7 denotes a transmission line connecting the television UHF antenna 2 and the first amplification unit 3. Used.

Reference numeral 8 denotes a transmission line connecting the first amplification unit 3 and the second amplification unit 4 and is wired over a long distance from the roof A to the room B. For example, a coaxial cable is used.

Reference numeral 9 denotes a transmission line connecting the second amplifying unit 4 and the television receiver 5, and for example, a coaxial cable is also used.

The first amplifier 3 includes a first input terminal 3a and a second input terminal 3b.
A VHF television signal is applied to one input terminal, and a UHF television signal is applied to the other input terminal.

3c is an output terminal, 11 is a first VHF amplifying element, 12 is a first UHF
Amplifying element, 13 indicates a mixer, and 14 indicates a power supply separation filter.

The second amplifying unit 4 has an input terminal 4a and an output terminal.

15 is a power supply separation filter, 16 is a duplexer, 17 is a VHF variable attenuator, 18 is a UHF variable attenuator, and these variable attenuators 17 and 18 change the amount of attenuation stepwise or continuously. What can do is used.

19 is a second VHF amplification element, 20 is a second UHF amplification element, 21
Indicates a mixer, 22 indicates an AC plug, 23 indicates a power transformer, and 24 indicates a rectifying / smoothing circuit.

25 is an AC code, 26 is a knob for adjusting the amount of attenuation of the VHF variable attenuator 17, 27 is a knob for adjusting the amount of attenuation of the UHF variable attenuator 18, and 28 is a viewer. .

Here, the operation of the television receiving amplifier configured as described above will be described.When the AC plug 22 is inserted into the power outlet and the commercial power is applied to the transformer 23, the rectifying / smoothing circuit 24 converts the DC voltage to a constant voltage. You.

This DC voltage is applied to the first VHF amplification element 11 and the second VHF
In addition to the HF amplification element 19, the first UHF amplification element 12 and the second UHF amplification element 20.

On the other hand, the VHF television signal received by the television VHF antenna 1 is supplied to the first input terminal 3a of the first amplifier 3, and the UHF television signal received by the television UHF antenna 2 is transmitted to the first input terminal 3a. , Respectively.

The VHF television signal is amplified by a first VHF amplification element 11, and the UHF television signal is amplified by a first UHF amplification element 12 and then mixed by a mixer 13.

The signal output from the mixer 13 is supplied to a power separation filter 14.
And the transmission line 8, and is applied to the input terminal 4 a of the second amplifying unit 4.

This signal passes through the power supply separation filter 15 in the second amplifying unit 4 and is split by the splitter 16. Of the signals obtained by splitting, the VHF television signal is transmitted to the variable attenuator 17 and the second attenuator 17. VHF
The other UHF television signal is sent to the mixer 21 through the amplification element 19 and to the mixer 21 through the variable attenuator 18 and the second UHF amplification element 20.

In the mixer 21, the VHF television signal and the UHF television signal are mixed and output from the output terminal 4b, and the output signal is received by the television receiver 5 through the transmission line 9.

For VHF television signals, the signal level at each point in the television receiving system and the gain or loss of each circuit member are as shown in Table 1. In this Table 1, the term VHF indicating the band used is omitted. Is shown.

For UHF television signals, antenna 1 in Table 1 was used.
To the antenna 2, the variable attenuator 17 to the variable attenuator 18, and the second amplifying element 19 to the second amplifying element 20, respectively.

As is clear from Table 1, the first VHF amplification element 11
The output level is a medium output of at most 100 dBμ.

This means that it is not necessary to use a high-output amplifying element for the first VHF amplifying element 11, and the amplifier can be configured at low cost.

Further, the television receiving amplifier of the embodiment has a rectifying / smoothing circuit 24 only in the second amplifying unit 4 and outputs the output to the first amplifying unit 3 via the power supply separation filter 15 and the transmission line 8. Since supply is performed, there is also an advantage that only one rectifying / smoothing circuit is required.

Further, the gain of the first amplifying element 11 is set so as to prevent the amplifying element from being distorted even if the output of the antenna 1 is relatively high at 80 dBμ.
The gain of the second amplifying element 19 is set to about 10 dB, so that a signal of a sufficient level can be sent to the television receiver 5 even if the output of the antenna 1 is relatively low at 50 dBμ. I have.

This enables a good quality signal to be sent to the television receiver 5 regardless of whether the antenna output 1 is as low as 50 dBμ or as high as 80 dBμ.

Next, an example of a television receiving amplifier having the configuration of the present invention will be described with reference to FIG.

In FIG. 3, components having the same or equivalent functions as those in the previous figure are denoted by the same reference numerals with the letter e added thereto, and overlapping description is omitted (FIG. 4 is also denoted by the letter f for the same reason). Shown).

3ae is a first input terminal, and the first input terminal 3ae is connected to the first VHF amplifier 1
Connected to 1e.

3d is a second input terminal, 30 is a low-pass filter through which a VHF television signal passes, 31 is a high-pass filter through which a UHF television signal passes, and the second input terminal 3d is a low-pass filter 30 and the switch 32. Through the first
Connected to VHF amplification element 11e and high-pass filter
It is connected to the first UHF amplifying element 12e via 31.

With such a configuration, the input terminal connected to the VHF amplification element 11e can be selected from the first input terminal 3d and the second input terminal 3ae by the changeover switch 32.

 Reference numeral 33 denotes a terminating resistor.

This TV receiver amplifier uses two different antennas, one for TV VHF reception only and the other for TV UHF reception.
When the HF television signal and the UHF television signal are separately input, the television VHF reception-only antenna is connected to the first input terminal 3ae, and the television UHF reception-only antenna is connected to the second input terminal 3d. The changeover switch 32 is operated to the contact 32a side to transmit the VHF television signal to the first input terminal 3ae and to transmit the VHF television signal to the first VHF amplification element 11e, while the second input terminal
The UHF television signal added to 3d is transmitted to the first UHF amplification element 12e through a high-pass filter 31.

When a mixed signal of a VHF television signal and a UHF television signal is input using an all-band antenna that covers a television VHF and a television UHF, the all-band antenna is connected to the second input terminal 3d. Connect and switch
By operating the contact 32 to the contact 32b side, U applied to the second input terminal 3d
The HF television signal is passed through the high-pass filter 31 and
To the UHF amplification element 12e of the second input terminal 3d
Is transmitted to the first VHF amplification element 11e.

In this way, even if the antenna used is a set of two different antennas dedicated to television VHF reception and television UHF reception only, or an all-band antenna covering the television VHF and the television UHF, wiring can be easily performed. be able to.

The second amplifying unit in the above embodiment includes a second VHF amplifying element 19 and a second UHF amplifying element 20.
As shown in the figure, the second amplifying unit 4f has the second amplifying element as the amplifying element.
May be provided only with the UHF amplification element 20f.

(Effects of the Invention) According to the present invention, in addition to the effect of being excellent in workability at the time of installation and enjoying a high-quality image, a case where two types of antennas are used, only for television VHF reception and only for television UHF reception, In either case of the TV VHF and the all-band type covering the TV UHF, the operation can be performed by operating the changeover switch, so that there is no need to worry about the antenna to be combined.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a television receiving system using a television receiving amplifier having a built-in mixer, and FIG.
FIG. 3 is a schematic diagram of a television receiving system shown in FIG. 3, FIG. 3 is a block circuit diagram showing a first amplifier in a television receiving amplifier of the present invention, and FIG. 4 shows a modification example relating to a second amplifier. It is a block circuit diagram. 1 ... antenna (for TV VHF), 2 ... antenna (for TV UHF), 3 ... first amplifier, 3ae ... 1st input terminal, 3d ... 2nd input terminal, 4 ... Second amplification section, 5 ...
TV receiver, 8 ... transmission line, 11.11e ... 1st (VH
F) Amplification element, 12.12e ... first (UHF) amplification element, 13.1
3e: Mixer, 17: Variable attenuator (VHF), 18: Variable attenuator (UHF), 19: Second (VHF) amplifying element, 20:
Second (UHF) amplification element, 26 ... VHF knob, 27 ... UH
F knob, 30 ... Low-pass filter, 31 ... High-pass filter, 32 ... Switch.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H03G 3/00-3/34 H04B 1/18-1/24 H04N 5/38-5/46

Claims (1)

(57) [Claims] A first amplifier having a first amplifying element and disposed near an antenna; a second amplifier having a second amplifying element and disposed near a television receiver; A television receiving amplifier comprising a variable attenuator provided in series with a second amplifying element, wherein the first amplifying element is connected to a first input terminal via a changeover switch. A first VHF amplification element connected to the second input terminal via the changeover switch and the low-pass filter, and a first UHF amplification element connected to the second input terminal via the high-pass filter. And an input terminal connected to the first VHF amplifying element by the changeover switch, which can select either the first input terminal or the second input terminal.