JPH08163532A - Reception point signal amplification method for catv system and reception point amplifier used for it - Google Patents

Abstract

PURPOSE: To obtain the CATV reception point amplifier simple in constitution by converting a reception signal of plural channels into an intermediate frequency signal with the same frequency for each channel and amplifying the converted signal so as to adopt identical configuration to each frequency conversion amplifier unit of each channel. CONSTITUTION: A VHF equipment input signal of plural channels is distributed to each frequency conversion amplifier unit 10 via an input section 3. Each input signal is converted into an intermediate frequency of the same frequency by a VCO 12 of a 1st frequency conversion section 5 and a frequency converter 14 of the unit 10 and processed by a BPF 11 and an amplifier 1. This is similar to the processing of an input OHF signal and then the frequency conversion amplifier unit 10 with the same configuration of the 1st frequency control section 5, the BPF 11, and the amplifier 10 or the like is employed and the CATV reception point amplifier with simple configuration and easily coping with increase in the number of channels is realized. Furthermore, the 2nd frequency conversion section 6 is used to restore an output signal frequency to a frequency of the original signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of amplifying a received signal at a receiving point such as a head end in a CATV system and a receiving point amplifier used for the method.

[0002]

2. Description of the Related Art One of receiving point amplifiers used in a CATV system is called a channel proper amplifier. In this system, a signal is extracted from a received signal for each channel and each is amplified so that the level of each channel is made uniform. As an example thereof, there is a conventional one shown in FIG.

[0003] This channel proper amplifier is a multi-channel reception signal (FM band signal, VHF band signal, UHF band signal) input to the input section A, both FM band and VHF band signals. About the dedicated band pass filter (BP) for each channel
F) The signal is passed through B ₁ , B _2, ... And separated into signals for each channel here, and the signals of each channel are amplified to a predetermined level by the amplification units C ₁ , C ₂ ,. Dedicated band pass filter D ₁ , D ₂ ...
・ After passing through, input to the mixing section E. On the other hand, the signal input to the input section A of the UHF band is converted into a VHF band signal for each channel through the UHF → VHF converters F ₁ and F ₂ for each channel, and the VHF band signal for each channel is converted.
The HF signal is amplified to a predetermined level by the amplification units G ₁ and G ₂ for each channel, and these are band-passed for each channel.
It is input to the mixing section E after passing through the filters H ₁ and H ₂ .
The signal output from the mixing section E is amplified by the output amplification section I and output to the outside through the output section J.

[0004]

However, the channel proper amplifier shown in FIG. 2 has the following problems. ． Dedicated band pass filters B ₁ , B ₂ ..., Band pass filters D ₁ , D different for each channel
₂ ... is required and many band pass filters must be facilitated. ． In order to handle a UHF band signal, a unit having a different configuration from the FM band or VHF band signal, that is, U
A unit equipped with the HF → VHF converters F ₁ and F ₂ is required. ． The channel of the received signal differs depending on the CATV station, and there are many channel variations, so
In order to correspond to the broadcasting channel of each station, prepare several kinds of channel proper amplifiers with different configurations of band pass filter and UHF → VHF converter in advance, or configure the amplifier after receiving the order. However, it is very difficult to prepare multiple types of amplifiers with different configurations in advance, and even if the configuration is changed after receiving an order, it is necessary to replace parts. Therefore, the work is troublesome.

An object of the present invention is to provide a receiving point signal amplifying method for a CATV system which can easily cope with a change or addition of a receiving channel and has a simple structure, and a receiving point amplifier used therefor. It is in.

[0006]

According to a first aspect of the present invention, a method of amplifying a reception point signal of a CATV system according to a first aspect of the present invention is as shown in FIG. Intermediate frequency signal of each channel is amplified by the intermediate frequency amplification unit 1 of each channel, the intermediate frequency signal of each channel is converted into a transmission frequency signal of a different frequency for each channel, It is characterized in that the signals are mixed and amplified by the output amplifier 2.

According to a second aspect of the present invention, the CATV reception point amplifier amplifies the reception signals of two or more channels input to the input section 3 for each channel to make the signal levels of the respective channels uniform, and In a CATV reception point amplifier configured to mix and output signals in a mixer 4,
Between the input unit 3 and the mixing unit 4, a first frequency conversion unit 5 that converts the received signal of each channel to the same intermediate frequency, an intermediate frequency amplification unit 1 that amplifies the frequency-converted intermediate frequency signal, and an amplifier A second frequency converter 6 for frequency-converting the generated intermediate frequency signal into a transmission frequency signal having a predetermined frequency is provided.

The CATV receiving point amplifier according to claim 3 of the present invention is characterized in that the first frequency converting section 5, the intermediate frequency amplifying section 1, and the second frequency converting section 6 are unitized. To do.

[0009]

In the receiving point signal amplifying method of the CATV system according to the first aspect of the present invention, the input received signals of two or more channels are converted into intermediate frequency signals of the same frequency for each channel, and the intermediate signals of each channel are converted. The frequency signal is amplified by the intermediate frequency amplification unit 1 for each channel, the intermediate frequency signal of each channel is converted into a transmission frequency signal having a different frequency for each channel, and then these transmission frequency signals are mixed and amplified, It is not necessary to change the circuit configuration of the intermediate frequency amplification unit 1 and the circuit configuration before and after it, and it is possible to use the same circuit configuration for all. For example, the band pass filter 11 attached in front of the intermediate frequency amplification unit 1 may be the same.

In the receiving point amplifier for CATV according to the second aspect of the present invention, between the input section 3 and the mixing section 4, there is provided a first frequency conversion section 5 for converting the reception signal of each channel into the same intermediate frequency. Since the intermediate frequency amplification unit 1 for amplifying the frequency-converted intermediate frequency signal and the second frequency conversion unit 6 for frequency-converting the amplified intermediate frequency signal into the transmission frequency signal of the predetermined frequency are provided, 2 entered in part 3
The received signals of the above channels are converted into intermediate frequency signals of the same frequency for each channel, the intermediate frequency signals of each channel are amplified by the intermediate frequency amplification unit 1 of each channel, and the intermediate frequency signals of each channel are different for each channel. Converted to transmission frequency signals of frequencies, these transmission frequency signals are then mixed and amplified. Therefore, in this receiving point amplifier, the frequency conversion of the signal by the first frequency conversion unit 5 and the second frequency conversion unit 6 is simply changed without changing the circuit structure of the intermediate frequency amplification unit 1, and each channel and It is possible to flexibly respond to changes in bands.

In the receiving point amplifier for CATV according to claim 3 of the present invention, the first frequency conversion section 5, the intermediate frequency amplification section 1, and the second frequency conversion section 6 are unitized, and therefore the number of channels is increased. Can be easily changed by attaching and detaching the unit, and the channel can be easily changed for each unit.

[0012]

Embodiment 1 An embodiment of a receiving point signal amplifying method for a CATV system of the present invention and a receiving point amplifier used for the method will be described with reference to FIG. Reference numeral 3 shown in FIG. 1 is an input unit of the reception point amplifier. This input unit 3 is a VHF band signal input to the VHF IN terminal and a UHF signal input to the UHF IN terminal.
The band signal is distributed to the frequency conversion amplifier unit 10 described later and output.

Reference numeral 10 shown in FIG. 1 is a frequency conversion amplifier unit of a reception point amplifier. This amplifier unit has a first frequency conversion section 5, a band pass filter 11, an intermediate frequency amplification section 1 and a second frequency conversion section, respectively, as shown in FIGS. 6 and 6.

The first frequency converter 5 frequency-converts the input signal into an intermediate frequency signal having a desired frequency.
First VCO (voltage controlled variable frequency oscillator) 12 and first
The frequency converter 14 of FIG. The frequency conversion unit 5 can convert the signal input to the frequency converter 14 into a signal of a desired frequency (intermediate frequency signal) by variably controlling the oscillation frequency of the VCO 12 and, therefore, This VCO1 for each amplifier unit 10
The oscillation frequency of 2 is adjusted so that the signals input to the amplifier unit 10 are all converted to the same intermediate frequency signal by the frequency conversion section 5. The first frequency converter 5 is capable of converting both a VHF band signal and a UHF band signal to a predetermined intermediate frequency. Although not shown, it is possible to support FM band signals.

The band pass filter 11 is capable of passing only an intermediate frequency signal, and each amplifier unit 10 has the same band pass filter 1.
1 is attached.

The intermediate frequency amplification unit 1 amplifies the intermediate frequency signal, and the same intermediate frequency amplification unit 1 is attached to each amplifier unit 10.

The second frequency conversion section 6 frequency-converts the intermediate frequency signal amplified by the intermediate frequency amplification section 1 into a transmission frequency signal having a desired frequency, and is composed of a VCO and a second frequency converter 15. It is configured. Regarding the VCO, by switching the switch SW, the first VCO 12 and the second VCO 12
Either of CO13 can be selected, and when the contact of the switch SW is connected to the a side,
When the signal input to the frequency converter 15 is converted into a signal having the same frequency as the reception frequency and the contact of the switch SW is connected to the b side, the oscillation frequency of the second VCO 13 is adjusted to be different from the reception frequency. It can be converted into a frequency signal and output. In the latter case, the oscillation frequency of the second VCO 13 can be arbitrarily set for each amplifier unit 10, and the reception signal can be transmitted on another channel different from the reception channel.

The frequency conversion amplifier unit 1
0 is unitized and is configured to be attachable / detachable in the case (not shown) of the reception point amplifier. Therefore, it is easy to increase or decrease the number of amplifier units 10 to be set in the amplifier according to the number of broadcasting channels of the broadcasting station of the CATV system.

In this case, the first of each amplifier unit 10 is
The frequency converter 5 of the first converter converts the input received signal into an intermediate frequency signal of the same frequency for each channel.
The oscillation frequency of the VCO 12 is adjusted and each amplifier
All the signals amplified by the intermediate frequency amplifier 1 of the unit 10 have the same frequency. Therefore, each amplifier
The intermediate amplification unit 1 of the unit 10 and the band pass filter 11 provided in front of the intermediate amplification unit 1 have the same configuration.

Further, in the second frequency converter 6 of each amplifier unit 10, when the contact of the changeover switch SW is set to the side of the terminal a (FIG. 1 (b)), each frequency converter 15 moves from the first VCO 12 to the other. The intermediate frequency signal amplified by the intermediate amplifier 1 is converted into the original frequency (frequency at the time of reception) by the frequency converter 15, and the contact of the changeover switch SW is On the b side {Fig. 1
(C)}, each frequency converter 15 operates by receiving the oscillating frequency from the second VCO 13, and the intermediate frequency signal amplified by the intermediate amplifying unit 1 is returned to the original frequency (frequency at the time of reception) by the frequency converter 15. ) Is converted into a signal of a different frequency.

In this frequency conversion amplifier unit 10, even when the frequency of the input signal changes (channel changes), the oscillation frequency of the first VCO 12 in the unit 10 is changed to change the frequency of the intermediate frequency signal. Since it can be changed as desired, VCO12
It is possible to support various channels simply by adjusting.

When the contact of the changeover switch SW is set to the side b, the frequency of the output signal can be set to a frequency (channel) different from the frequency at the time of reception. In this case, the oscillation frequency of the second VCO 13 is changed. Thus, the frequency of the output signal can be changed to a desired channel.

Reference numeral 4 shown in FIG. 1 is a mixing section of the reception point amplifier, which mixes the signals output from the respective frequency conversion amplifier units 10 and outputs them.

Reference numeral 2 shown in FIG. 1 denotes an output amplifier, which amplifies the signal output from the mixer 4 to a predetermined level and outputs the amplified signal.

Reference numeral 16 shown in FIG. 1 denotes an output section, which branches the signal amplified by the output amplification section 2 into an output terminal and an output monitor terminal for output.

[0026]

According to the CATV system reception point signal amplification method of the present invention, the following effects can be obtained. ． Since all the received signals of the respective channels are converted into intermediate frequency signals of the same frequency and then amplified, the structure of the amplification section can be made the same regardless of the channels. ． Since the received signal of UHF is also converted into the intermediate frequency signal in the same manner, the amplification unit for UHF can have the same configuration as the other (amplification unit for VHF). ． Therefore, an amplifier having a simple structure can be manufactured.

The CATV reception point amplifier of the present invention has the following effects. ． Since the circuit configuration of the frequency conversion amplifier unit provided for each channel is the same, the structure of the amplifier is simplified. ． Therefore, the manufacturing cost of the amplifier can be reduced. ． It is possible to flexibly deal with the change of the receiving channel and the change of the transmitting channel, and the work therefor is easy. ． The number of channels can be easily increased or decreased.

[Brief description of drawings]

FIG. 1 is an embodiment of a receiving point amplifier for CATV of the present invention, (a) is an overall block diagram of the same amplifier, and (b) is
(C) is a partial block diagram around the amplification unit.

FIG. 2 is a block diagram showing an example of a conventional channel proper amplifier.

[Explanation of symbols]

 1 Intermediate Frequency Amplifier 2 Output Amplifier 3 Input 4 Mixing 5 First Frequency Converter 6 Second Frequency Converter

Claims (3)

[Claims] 1. Converting input received signals of two or more channels into intermediate frequency signals of the same frequency for each channel,
The intermediate frequency signal of each channel is amplified by the intermediate frequency amplification unit (1) for each channel, and the intermediate frequency signal of each channel is converted into a transmission frequency signal having a different frequency for each channel,
A method of amplifying a reception point signal of a CATV system, characterized in that these transmission frequency signals are mixed and amplified by an output amplification section (2). 2. A received signal of two or more channels input to an input section (3) is amplified for each channel to make the signal level of each channel uniform, and these signals are mixed and output by a mixing section (4). In the CATV reception point amplifier, the first frequency conversion unit (5) for converting the reception signal of each channel to the same intermediate frequency is provided between the input unit (3) and the mixing unit (4), and the frequency. An intermediate frequency amplification unit (1) for amplifying the converted intermediate frequency signal and a second frequency conversion unit (6) for frequency converting the amplified intermediate frequency signal into a transmission frequency signal of a predetermined frequency. Characteristic CAT
Receiver amplifier for V. 3. The CATV according to claim 2, wherein the first frequency converter (5), the intermediate frequency amplifier (1) and the second frequency converter (6) are unitized. Receiver amplifier.