KR0131966B1 - Transmission frequency stabilization circuit of cable television - Google Patents

Transmission frequency stabilization circuit of cable television

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Publication number
KR0131966B1
KR0131966B1 KR1019940028010A KR19940028010A KR0131966B1 KR 0131966 B1 KR0131966 B1 KR 0131966B1 KR 1019940028010 A KR1019940028010 A KR 1019940028010A KR 19940028010 A KR19940028010 A KR 19940028010A KR 0131966 B1 KR0131966 B1 KR 0131966B1
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KR
South Korea
Prior art keywords
transmission
receiving
data
pll
frequency
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KR1019940028010A
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Korean (ko)
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KR960016572A (en
Inventor
김종운
Original Assignee
김회수
엘지전자부품주식회사
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Application filed by 김회수, 엘지전자부품주식회사 filed Critical 김회수
Priority to KR1019940028010A priority Critical patent/KR0131966B1/en
Publication of KR960016572A publication Critical patent/KR960016572A/en
Application granted granted Critical
Publication of KR0131966B1 publication Critical patent/KR0131966B1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/20—Circuitry for controlling amplitude response
    • H04N5/205—Circuitry for controlling amplitude response for correcting amplitude versus frequency characteristic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/455—Demodulation-circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/50—Tuning indicators; Automatic tuning control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/10—Adaptations for transmission by electrical cable

Abstract

A circuit for stabilizing a transmitting frequency of a cable television is disclosed. The apparatus comprises a receiver(10) for receiving a required channel signal by performing a tuning operation and an oscillation operation according to a receiving control data(DATA, RX ENABLE, CLOCK) from a microcomputer; a unit(20) for reducing the level of a transmitting data(TX DATA); a transmitting unit(30) for transmitting the required channel by performing the tuning operation and the oscillation operation based on a transmitting control data(DATA, TX ENABLE, CLOCK) and the output signal from the reducing unit; a transmitting switch(40) performing an "ON" operation in case that the signal is only transmitted from the transmitting unit and the reducing unit; and a unit(50) for amplifying the output signal from the transmitting unit to a required level.

Description

케이블 텔레비젼용 송신주파수 안정화회로Transmission frequency stabilization circuit for cable television

제 1도는 종래 기술에 의한 블럭도,1 is a block diagram according to the prior art,

제 2도는 본원 발명에 의한 블럭도.2 is a block diagram according to the present invention.

＊ 도면의 주요부분에 대한 부호의 설명＊ Explanation of symbols on main parts of drawing

10 : 수신부 11 : 수신 PLL10: receiving unit 11: receiving PLL

12 : 수신발진부 20 : 감쇠기12: reception oscillator 20: attenuator

30 : 송신부 31 : 송신 PLL30: transmitting unit 31: transmitting PLL

32 : 송신발진부 40 : 송신스위치32: transmission oscillator 40: transmission switch

50 : 송신증폭기50: transmit amplifier

본원 발명은 케이블 텔레비젼용 송신주파수 안정화회로에 관한 것으로서 특히, 입력된 송신데이타를 직접 송신주파수에 변조를 걸어서 송신 주파수를 안정화시키는 케이블 텔레비젼용 송신주파수 안정화회로에 관한 것이다. 종래 기술에 의한 케이블 텔레비젼(CATV)용 송신주파수 안정화회로는 제1도에 도시된 바와 같이 마이컴(미도시)으로부터 제어데이타(DATA, ENABLE, CLOCK)를 입력받아 동조전압(Ｖ t) 을 출력하는 위상잠김루프(Phase Locked Loop : 이하 PLL이라 한다. )(110)와, 상기 PLL(110)에서 출력되는 동조전압(Ｖ t)을 입력받아 발진주파수(f osc) 를 출력하는 국부발진회로(120)와, 상기 국부발진회로(120)에서 출력되는 발진주파수(f osc) 를 3개로 분배하는 버퍼회로(130)와, 송신데이타(TX DATA)의 레벨을 감쇠시키는 감쇠기(140)와, 상기 감쇠기(140)의 출력을 입력받아 송신데이타(TX DATA)를 변조시키기 윈한 고정주파수(f fix)를 출력하는 고정발진회로(150)와, 상기 버퍼회로(130) 및 고정발진회로(150)의 출력을 입력받아 혼합하여 송신주파수(f tx)를 출력하는 혼합기(160)와, 상기 혼합기(160)의 출력을 원하는 레벨로 증폭하는 송신증폭기(170)로 구성된다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission frequency stabilization circuit for cable television, and more particularly, to a transmission frequency stabilization circuit for cable television that stabilizes the transmission frequency by modulating the input transmission data directly to the transmission frequency. The transmission frequency stabilization circuit for a cable television (CATV) according to the prior art receives control data (DATA, ENABLE, CLOCK) from a microcomputer (not shown) and outputs a tuning voltage ( Ｖ t ) as shown in FIG. Phase locked loop (PLL) 110 and a local oscillation circuit 120 for outputting an oscillation frequency f osc by receiving a tuning voltage ( Ｖ t ) output from the PLL 110. ), A buffer circuit 130 for distributing the oscillation frequency f osc output from the local oscillation circuit 120 into three, an attenuator 140 for attenuating the level of TX data, and the attenuator A fixed oscillation circuit 150 for outputting a fixed frequency f fix for receiving the output of the 140 and modulating the transmission data TX data, and an output of the buffer circuit 130 and the fixed oscillation circuit 150. A mixer 160 for mixing and outputting a transmission frequency f tx , and the mixer ( And a transmission amplifier 170 for amplifying the output of the controller 160 to a desired level.

상기 버퍼회로(130)에서 출력되는 3개의 발진주파수(f osc)는 각각 수신복조부(미도시), PLL(110), 혼합기(160)로 입력된다. 상기와 같이 구성되어 상기 PLL(110)에서 마이컴(미도시)에서 출력되는 제어데이타(DATA, ENABLE, CLOCK)를 입력받아 동조전압(V t)을 출력하면 상기 국부발진회로(120)에서는 동조전압(V t)을 입력받아 발진주파수rm (f osc)를 출력하고, 상기 버퍼회로(130)에서는 상기 발진주파수를 3개로 분배하여 출력한다.The three oscillation frequencies f osc output from the buffer circuit 130 are input to a reception demodulator (not shown), a PLL 110, and a mixer 160, respectively. When the PLL 110 receives the control data DATA, ENABLE, and CLOCK output from the microcomputer (not shown) and outputs a tuning voltage V t , the local oscillation circuit 120 tunes the tuning voltage. The oscillation frequency rm ( f osc ) is outputted after receiving ( V t ), and the buffer circuit 130 divides the oscillation frequency into three and outputs the oscillation frequency.

이때, 상기 PLL(110)로 피드백되는 발진주파수rm (f osc)는 내부의 분주기에 의해 카운트되고, 기준주파수와 비교되어 상기 국부발진회로(120)에서 원하는 주파수로 발진되면 상기 PLL(110)은 잠김상태(LOCK)가 된다. 상기 PLL(110)이 잠김상태에서 발생되는 상기 국부발진회로(120)의 발진주파수rm (f osc)는 상기 버퍼회로(130)를 통해 상기 혼합기(160)로 입력된다. 한편, 감쇠기(140)에서는 송신데이타(TX DATA)의 레벨을 감쇠시키고, 상기 고정발진회로(150)에서는 상기 감쇠기(140)의 출력을 입력받아 송신데이타(TX DATA)를 변조시키기 위한 고정주파수rm (f fix)를 출력한다. 상기 혼합기(160)에서는 상기 버퍼회로(130) 및 고정발진회로(150)의 출력을 입력받아 혼합하여 발진주파수rm (f osc)-고 정주파수rm (f fix)의 송신주파수rm (f tx)를고,상기 송신증폭기(170)에서는 상기 혼합기(160)의 출력을 하는 레벨로 증 안테나를 통해 방송국에 전달된다.At this time, the oscillation frequency rm ( f osc ) fed back to the PLL 110 is counted by an internal divider, and when compared with a reference frequency, the oscillation frequency is oscillated at a desired frequency in the local oscillation circuit 120. Is locked. The oscillation frequency rm ( f osc ) of the local oscillation circuit 120 generated when the PLL 110 is locked is input to the mixer 160 through the buffer circuit 130. On the other hand, the attenuator 140 attenuates the level of the transmission data TX DATA, and the fixed oscillation circuit 150 receives the output of the attenuator 140 and receives a fixed frequency rm for modulating the transmission data TX DATA. Print ( f fix ). The mixer 160 receives and mixes the outputs of the buffer circuit 130 and the fixed oscillation circuit 150, and transmits the oscillation frequency rm ( f osc ) -the fixed frequency rm ( f fix ) of the transmission frequency rm ( f tx ). In the transmission amplifier 170, the output of the mixer 160 is transmitted to a broadcasting station through an amplification antenna.

상기와 같이 구성되고 동작하는 종래 기술에 의한 케이블 텔레비젼용 송신주파수 안정화회로는 상기 PLL(110)에 의해 제어되는 발진주파수rm (f osc)는 안정적으로 고정되지만 상기 고정발진회로(150)에서 발진되는 고정주파수rm (f tx)는 전원이나 온도변화에 따라 변화가 발생하기 때문에 최종 출력되는 송신주파수rm (f tx)가 불안정하게 되는 문제점이 있다.In the transmission frequency stabilization circuit for cable television according to the related art constructed and operated as described above, the oscillation frequency rm ( f osc ) controlled by the PLL 110 is stably fixed but oscillated in the fixed oscillation circuit 150. Since the fixed frequency rm ( f tx ) changes according to power or temperature changes, the final output frequency rm ( f tx ) becomes unstable.

또한, 수신측의 PLL에 의해 채널이 고정되기 때문에 송신채널은 항상 수신채널과 동일해야 하는 문제점이 있다. 본원 발명은 상기와 같은 문제점을 해결하기 위하여 안출한 것으로서, 수신측과 송신측의 PLL을 독립적으로 구성하고 입력되는 송신데이타를 직접 송신주파수에 변조를 걸어서 송신주파수를 안정하도록 하는 케이블 텔레비젼용 송신주파수 안정화회로를 제공함에 그 목적이 있다.In addition, since the channel is fixed by the PLL on the receiving side, there is a problem that the transmitting channel should always be the same as the receiving channel. The present invention has been made to solve the above problems, and the transmission frequency for cable television to stabilize the transmission frequency by configuring the PLL of the receiving side and the transmitting side independently and modulating the input transmission data directly to the transmission frequency. The purpose is to provide a stabilization circuit.

상기와 같은 목적을 달성하기 위한 본원 발명에 의한 케이블 텔레비젼용 송신주파수 안정화회로는 마이컴으로부터 입력되는 수신제어데이타(DATA, RX ENABLE, CLOCK)에 따라 동조 및 발진을 수행하여 원하는 채널을 수신하는 수신부와, 송신데이타(TX DATA)의 레벨을 감쇠시켜 출력하는 감쇠기와, 상기 마이컴으로부터 출력되는 송신제어데이타(DATA, TX ENABLE, CLOCK)를 입력받는 동시에 상기 감쇠기의 출력신호를 입력받아 동조 및 발진을 수행하여 원하는 채널을 송신하는 송신부와, 상기 송신부 및 감쇠기에 연결되어 송신하는 경우에만 온(on)시키는 송신스위치와 상기 송신부의 출력을 원하는 레벨로 증폭하는 송신증폭기로 구성되어 전원 및 온도변화에 안정하고 각기 다른 채널로 쌍방향 통신이 가능한 것을 특징으로 한다.The transmission frequency stabilization circuit for cable television according to the present invention for achieving the above object is a receiver for receiving a desired channel by performing tuning and oscillation according to the reception control data (DATA, RX ENABLE, CLOCK) input from the microcomputer and And attenuator for attenuating and outputting the level of TX data, and transmission control data DATA, TX ENABLE, and CLOCK outputted from the microcomputer, and simultaneously receiving and outputting the output signal of the attenuator to perform tuning and oscillation. And a transmission unit for transmitting a desired channel, a transmission switch which is connected to the transmission unit and an attenuator only when transmitting, and a transmission amplifier which amplifies the output of the transmission unit to a desired level. Two-way communication is possible through different channels.

이하, 본원 발명에 의한 케이블 텔레비젼용 송신주파수 안정화회로의 바람직한 실시예를 첨부한 도면을 참조하여 상세히 설명한다.Hereinafter, a preferred embodiment of a transmission frequency stabilization circuit for a cable television according to the present invention will be described in detail with reference to the accompanying drawings.

본원 발명은 제 2도에 도시된 바와 같이 마이컴(미도시)으로부터 입력되는 수신제어데이타(DTAT, RX ENABLE, CLOCK)에 따라 동조 및 발진을 수행하여 원하는 채널을 수신하는 수신부(10)와, 송신데이타(TX DATA)의 레벨을 감쇠시켜 출력하는 감쇠기(20)와, 상기 마이컴(미도시)으로부터 송신제어데이타(DATA, TX ENABLE, CLOCK)를 입력받는 동시에 상기 감쇠기의 출력신호를 입력받아 동조 및 발진을 수행하여 원하는 채널을 송신하는 송신부(30)와, 상기 감쇠기(20) 및 송신부(30)에 연결되어 송신하는 경우에만 온(ON)시키는 송신스위치(40)와 상기 송신부(30)의 출력을 원하는 레벨로 증폭하는 송신증폭기(50)로 구성된다. 상기의 수신부(10)는 수신제어신호에 따라 수신동조전압 (V trx)을 출력하는 수신 PLL(11)과, 상기 수신 PLL(11)의 수신동조전압 (V trx)에 따라 상기 수신 PLL(11) 및 수신복조부(미도시)로 수신주파수 (f rx)를 발진하는 수신발진부(12)로 구성된다. 상기의 송신부(30)는 송신제어신호에 따라 송신동조전압 (V trx)을 력하는 송신 PLL(31)과, 상기 송신 PLL(31)의 송신동조전압 (V ttx)에 따라 상기 송신PLL(31)로 송신주파수rm (f tx)를 피드백하는 동시에 상기 송신증폭기(50)로 송신주파수rm (f tx)를 송신 발진부(32)로 구성된다.The present invention performs the tuning and oscillation according to the reception control data (DTAT, RX ENABLE, CLOCK) input from the microcomputer (not shown), as shown in FIG. Attenuator 20 for attenuating and outputting the level of data TX DATA, and transmission control data DATA, TX ENABLE, CLOCK are input from the microcomputer (not shown), and the output signal of the attenuator is received and tuned and Transmitter 30 to perform the oscillation and transmit a desired channel, the transmission switch 40 and the output of the transmitter 30 to be turned ON only when connected to the attenuator 20 and the transmitter 30 to transmit It consists of a transmission amplifier 50 for amplifying to a desired level. The receiving unit 10 receives a receiving PLL 11 that outputs a receiving tuning voltage V trx in accordance with a receiving control signal, and the receiving PLL 11 according to the receiving tuning voltage V trx of the receiving PLL 11. ) And a reception oscillator 12 for oscillating a reception frequency f rx to a reception demodulation unit (not shown). The transmitter 30 transmits a transmission PLL 31 that outputs a transmission tuning voltage V trx in accordance with a transmission control signal, and the transmission PLL 31 in accordance with a transmission tuning voltage V ttx of the transmission PLL 31. The transmission frequency rm ( f tx ) is fed back to the transmission amplifier 50 and the transmission frequency rm ( f tx ) is transmitted to the transmission amplifier 50.

상기와 같이 구성된 본원 발명은 원하는 채널을 수신하고자 하는 경우는 마이컴(미도시)에서 상기 수신PLL(11)을 동작시켜 수신발진부(12)에 수신동조저압rm (V trx)을 입력시켜 수신주파수rm (f rx)를 발진시킨다.According to the present invention configured as described above, when a desired channel is to be received, the reception tuner low voltage rm ( V trx ) is input to the reception oscillator 12 by operating the reception PLL 11 in a microcomputer (not shown). oscillates ( f rx ).

이때 발진된 수신주파수rm (f rx)`는 상기 수신 PLL(11) 및 수신복조부(미도시)로 입력된다.At this time, the oscillated reception frequency rm ( f rx ) `is input to the reception PLL 11 and a reception demodulator (not shown).

한편, 송신하는 경우는 송신스위치(40)를 온(ON)시켜서 송신발진부(32)에 전원을 공급하여 송신데이타(TX DATA)의 레벨을 상기 감쇠기(20)에서 감쇠시켜 출력하고, 마이컴(미도시)에서는 송신하고자 하는 채널에 대한 송신제어신호(TX ENABLE DATA CLOCK)를 출력한다. 상기 송신제어신호에 따라 상기 송신 PLL(31)이 동작하여 송신동조전압 (V ttx)을 출력하고, 그에 따라 상기 송신발진부(32)에서는 송신데이타(TX DATA)를 변조시켜, 송신주파수rm (f tx)를 발진시킨다.On the other hand, when transmitting, the transmission switch 40 is turned ON to supply power to the transmission oscillation unit 32 to attenuate the level of the transmission data TX DATA by the attenuator 20 and output the result. ) Outputs a transmission control signal (TX ENABLE DATA CLOCK) for the channel to be transmitted. In response to the transmission control signal, the transmission PLL 31 operates to output the transmission tuning voltage V ttx . Accordingly, the transmission oscillator 32 modulates the transmission data TX DATA to transmit the transmission frequency rm ( f). tx ).

이때, 송신데이타(TX DATA)는 교류(AC)신호로서 상기 감쇠기(20)에서 감소되고 송신동조전압 (V ttx)에 직접 변조되어 출력된다.At this time, the transmission data TX DATA is reduced by the attenuator 20 as an alternating current (AC) signal and directly modulated to the transmission tuning voltage V ttx and output.

상기 송신등조전압 (V ttx)은 직류(DC)전압레벨을 갖는 교류(AC)신호로서 직류전압에 의해 송신주파수 (f tx)가 발생되고, 교류신호에 의해 주파수변조(FM)가 된다.The transmission light modulation voltage V ttx is an alternating current (AC) signal having a direct current (DC) voltage level, and a transmission frequency f tx is generated by the direct current voltage, and the frequency modulation FM is caused by the alternating current signal.

상기와 같이 송신을 수행하는 동안에 상기 수신 PLL(11)은 상기 송신 PLL(31)과 무관하게 계속 동작상태가 된다.While performing the transmission as described above, the receiving PLL 11 continues to operate regardless of the transmitting PLL 31.

상기와 같이 구성되고 동작하는 본원 발명에 의한 케이블 텔레비젼용 송신주파수 안정화회로는 송신측과 수신측에 독립된 PLL을 구성하기 때문에 전원 및 온도변화에 따라 송신주파수 (f tx)를 안정적으로 고정할 수 있는 잇점이 있다.Since the transmission frequency stabilization circuit for cable television according to the present invention constructed and operated as described above constitutes an independent PLL on the transmitting side and the receiving side, the transmission frequency f tx can be stably fixed in accordance with power and temperature changes. There is an advantage.

또한, 송신측 및 수신측의 PLL이 마이컴의 제어신호중 각기 다른 신호에 따라 동작하기 때문에 완전쌍방향통신이 가능하고, 송신 및 수신시 다른 채널을 사용할 수 있는 잇점이 있다.In addition, since the PLL of the transmitting side and the receiving side operates according to different signals of the microcomputer's control signals, full bidirectional communication is possible, and other channels can be used for transmission and reception.

Claims (3)

마이컴으로부터 입력되는 수신제어데이타(DATA, RX ENABLE, CLOCK)에 따라 동조 및 발진을 수행하여 원하는 채널을 수신하는 수신부와, 송신데이타(TX DATA)의 레벨을 감쇠시켜 출력하는 감쇠기와 상기 마이컴으로부터 송신제어데이타(DATA TX ENALE CLOCK)를 입력받는 동시에 상기 감쇠기의 출력신호를 입력받아 동조 및 발진을 수행하여 원하는 채널을 송신하는 송신부와, 상기 송신부 및 감쇠기에 연결되어 송신하는 경우에만 온시키는 송신스위치와, 상기 송신부의 출력을 원하는 레벨로 증폭하는 송신증폭기로 구성된 것을 특징으로 하는 케이블 텔레비젼용 송신주파수 안정화회로.The receiver receives the desired channel by performing tuning and oscillation according to the reception control data (DATA, RX ENABLE, CLOCK) input from the microcomputer, the attenuator which attenuates and outputs the level of the transmission data (TX DATA), and transmits from the microcomputer. A transmission unit which receives a control data (DATA TX ENALE CLOCK) and at the same time receives the output signal of the attenuator and performs tuning and oscillation to transmit a desired channel; And a transmission amplifier for amplifying the output of the transmitter to a desired level. 제 1항에 있어서, 수신부는 수신제어신호에 따라 수신동조전압rm (V trx)을 출력하는 수신 PLL과, 상기 수신 PLL의 수신동조전압에 따라 상기 수신 PLL 및 수신복조부로 수신주파수 (f rx)를 발진하는 수신발진부로 구성된 것을 특징으로 하는 케이블 텔레비젼용 송신주파수 안정화회로.The receiver of claim 1, wherein the receiving unit outputs a receiving tuning voltage rm ( V trx ) according to a receiving control signal, and a receiving frequency f rx to the receiving PLL and the receiving demodulating unit according to the receiving tuning voltage of the receiving PLL. Transmission frequency stabilization circuit for a cable television, characterized in that consisting of a receiving oscillator for oscillating. 제 1항에 있어서, 송신부는 송신제어신호에 따라 송신동조전압 (V ttx)을 출력하는 송신 PLL과, 상기 송신 PLL의 송신동조전압에 따라 상기 송신 PLL로 송신주파수(f tx를 피드백하는 동시에 상기 송신증폭기로 송신주파수(f tx)를 출력하는 송신발진부로 구성된 것을 특징으로 하는 케이블 텔레비젼용 송신주파수 안정화 회로.The transmission PLL according to claim 1, wherein the transmitting unit feeds back a transmission frequency f tx to the transmission PLL outputting a transmission tuning voltage V ttx in accordance with a transmission control signal and the transmission PLL according to the transmission tuning voltage of the transmission PLL. A transmission frequency stabilization circuit for a cable television comprising a transmission oscillator for outputting a transmission frequency f tx to a transmission amplifier.
KR1019940028010A 1994-10-28 1994-10-28 Transmission frequency stabilization circuit of cable television KR0131966B1 (en)

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