KR960027863A - Carrier recovery device - Google Patents

Carrier recovery device Download PDF

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Publication number
KR960027863A
KR960027863A KR1019940034730A KR19940034730A KR960027863A KR 960027863 A KR960027863 A KR 960027863A KR 1019940034730 A KR1019940034730 A KR 1019940034730A KR 19940034730 A KR19940034730 A KR 19940034730A KR 960027863 A KR960027863 A KR 960027863A
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KR
South Korea
Prior art keywords
phase
frequency
phase difference
detector
carrier recovery
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KR1019940034730A
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Korean (ko)
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KR0132963B1 (en
Inventor
전성식
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구자홍
Lg 전자주식회사
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Priority to KR1019940034730A priority Critical patent/KR0132963B1/en
Publication of KR960027863A publication Critical patent/KR960027863A/en
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Publication of KR0132963B1 publication Critical patent/KR0132963B1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/38—Demodulator circuits; Receiver circuits
    • H04L27/3818—Demodulator circuits; Receiver circuits using coherent demodulation, i.e. using one or more nominally phase synchronous carriers
    • H04L27/3827—Demodulator circuits; Receiver circuits using coherent demodulation, i.e. using one or more nominally phase synchronous carriers in which the carrier is recovered using only the demodulated baseband signals
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
    • H03L7/08—Details of the phase-locked loop
    • H03L7/099—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0044—Control loops for carrier regulation
    • H04L2027/0053—Closed loops
    • H04L2027/0057—Closed loops quadrature phase
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0044—Control loops for carrier regulation
    • H04L2027/0063—Elements of loops
    • H04L2027/0067—Phase error detectors

Abstract

본 발명은 위성방송 수신기의 반송파 복구장치에 관한것으로서, 특히 QPSK(큐피에스케이: Quardrature Phase ShiftKeying) 변조파를 동기복조하기위해 중간주파수와 전압제어발진기의 주파수차를 이용하여 전 심볼과 현 심볼의 위상차로구하여 해당되는 위상차만큼 전압제어발진기를 제어함으로서 액퀴지션(Acquisition)상태에서도 주파수오차 검출능력이 뛰어난 반송파 복구장치에 관한 것이다.The present invention relates to a carrier recovery apparatus of a satellite broadcasting receiver. In particular, the phase difference between a current symbol and a current symbol using a frequency difference between an intermediate frequency and a voltage controlled oscillator for synchronous demodulation of a QPSK (Quardrature Phase Shift Keying) modulated wave. The present invention relates to a carrier recovery apparatus having excellent frequency error detection capability in an acquisition state by controlling a voltage controlled oscillator by a corresponding phase difference.

종래의 반송파 복구장치는 코스타스 루프(Costas Loop)를 이루고 있는 위상검출기, 기준발진기, 위상천이기 그리고, 비교기를 이용하여 2차중간주파수와 기준발진기의 출력주파수간의 위상차를 검출하여 검출된 위상차에따라 주파수를 제어하기 때문에, 일단 위상이 고정된 상태 즉, 트래킹(Tracking)상태에서 제1발진기의 온도 드리프트(Drift)에 따른 주파수 변화를 제2발진기를 제어하여 2차중간주파수를 안정화 할 수 있는 장점이 있다.The conventional carrier recovery apparatus detects the phase difference between the secondary intermediate frequency and the output frequency of the reference oscillator using a phase detector, a reference oscillator, a phase shifter, and a comparator in a Costas loop according to the detected phase difference. Since the frequency is controlled, the secondary intermediate frequency can be stabilized by controlling the second oscillator by changing the frequency according to the temperature drift of the first oscillator once the phase is fixed, that is, the tracking state. There is this.

그러나, 종래 반송파 복구장치는 초기상태 즉, 액퀴지션상태에서의 주파수 제어동작도 코스타스 루프로 실현하기 때문에,위상이 고정되지않은 액퀴지션상태에서 주파수 차이에 대한 검출능력이 떨어짐으로 반송파 복구동작에 대한 신뢰도가 저하되는 문제점이 있다.However, since the conventional carrier recovery apparatus realizes the frequency control operation in the initial state, that is, the acquisition state, by the Costas loop, the detection capability of the frequency difference is poor in the acquisition state in which the phase is not fixed. There is a problem that the reliability is lowered.

따라서, 본 발명은 상기 문제점을 해결하기위해 중간주파수와 전압제어발진기의 주파수차를 이용하여 전 심볼과 현 심볼의 위상차로 구하여 해당도는 위상차만큼어발진기를 제어함으로서 액퀴지션상태에서도 주파수오차 검출능력이 뛰어난 반송파 복구장치이다.Therefore, in order to solve the problem, the present invention obtains the phase difference between the previous symbol and the current symbol by using the frequency difference between the intermediate frequency and the voltage controlled oscillator, and controls the oscillator as much as the phase difference. This is an excellent carrier recovery device.

Description

반송파 복구장치Carrier recovery device

본 내용은 요부공개 건이므로 전문내용을 수록하지 않았음Since this is an open matter, no full text was included.

제2도는 본 발명 반송파 복구장치의 회로블럭도, 제3도는 본 발명의 반송파 복구장치에 사용된 카운터의 동작상태를 나타낸 상태천이도.2 is a circuit block diagram of a carrier recovery apparatus of the present invention, and FIG. 3 is a state transition diagram showing an operation state of a counter used in the carrier recovery apparatus of the present invention.

Claims (4)

입력단(I20)으로 입력되는 중간주파수 대역의 QPSK신호를 일정주파수에대한 동위상성분(I)과 직교위상성분(Q)의 디지탈신호로 변환시키는 주파수 변환부(20)와, 상기 주파수변환부(20)에서 변환된 QPSK신호의 벡터 위상값을 결정하고 위상값이 결정된 QPSK신호의 전 심볼과 현 심볼의 절대 위상차(△ψ)를 구하는 위상변환부(21)와, 트랙킹상태일때 상기 위상변환부(21)에서 구해진 위상차(△ψ)값으로 QPSK신호의 주파수 오차를 검출하고 검출된 주파수 오차를 보정하기위한 일정신호로 상기 위상변환부(21)의 출력을 제어하는 주파수 고정 검출부(22)와, 상기 위상변환부(21)에서 출력되는 일정신호에따라 상기 주파수변환부(20)의 주파수 변환동작을 제어하기위한 일정전압을 주파수 변환부(20)로 출력하는 제어부(23)로 구성된 것을 특징으로하는 반송파 복구장치.A frequency converter 20 for converting a QPSK signal of an intermediate frequency band input to the input terminal I20 into a digital signal of in-phase component I and quadrature phase component Q for a predetermined frequency; A phase shifter 21 for determining a vector phase value of the QPSK signal converted in step 20) and obtaining an absolute phase difference Δψ between all symbols of the QPSK signal having the phase value determined and the current symbol; A frequency fixed detector 22 which detects a frequency error of the QPSK signal using the phase difference Δψ value obtained in (21) and controls the output of the phase shifter 21 as a constant signal for correcting the detected frequency error; And a controller 23 for outputting a constant voltage for controlling the frequency conversion operation of the frequency converter 20 to the frequency converter 20 according to a predetermined signal output from the phase converter 21. Carrier recovery station . 제1항에 있어서, 상기 위상변환부(21)는 상기 주파수 변환부(20)에서 동위상성분(I)과 직교위상성분(Q)으로 샘플링된 QPSK신호의 벡터 위상값을 검출하는 위상검출기(39)와, 상기 위상검출기(39)에서 출력되는 QPSK신호의 벡터위상값을 한 심볼 지연시키는 지연기(40)와, 상기 위상검출기(39)에서 출력되는 QPSK신호의 현 심볼과 상기 지연기(40)에서 출력되는 전 심볼의 절대 위상차(△ψ)를 구하는 덧셈기(41)와, 상기 위상검출기(39)에서 출력되는 QPSK신호와 상기덧셈기(41)에서 출력되는 신호를 선택적으로 제어부(23)의 위상 오차 검출기(47)로 출력하는 멀티플렉서(42)로 구성된 것을 특징으로하는 반송파 복구장치The phase detector of claim 1, wherein the phase shifter 21 detects a vector phase value of a QPSK signal sampled by the frequency shifter 20 with in-phase component I and quadrature-phase component Q. 39), a delayer 40 for delaying the vector phase value of the QPSK signal output from the phase detector 39 by one symbol, a current symbol of the QPSK signal output from the phase detector 39, and the delayer ( The adder 41 which obtains the absolute phase difference Δψ of all symbols output from 40, the QPSK signal output from the phase detector 39 and the signal output from the adder 41 are selectively controlled. Carrier recovery device, characterized in that consisting of a multiplexer (42) for outputting to the phase error detector (47) 제1항에 있어서, 상기 주파수 고정 검출부(22)는 상기 위상변환부(21)의 덧셈기(41)에서 출력되는 위상차값이 일정레벨 이하일때를 검출하고 그 검출결과에따라 일정신호를 카운터(44)로 출력하는 오차검출기(43)와, 상기 오차검출기(43)에서 출력된 일정신호에따라 상기 오차검출기(43)의 검출횟수를 카운팅하는 카운터(44)와, 미리 설정된 기준값을 덧셈기(45)로 출력하는 기준값 발생기(46)와, 상기 카운터(44)의 카운팅 값에서 상기 기준값 발생기(46)의 기준값을 빼고 그 결과를 위상변환부(21)의 멀티플렉서(42)로 출력하는 덧셈기(45)로 구성된 것을 특징으로하는 반송파 복구장치.The frequency lock detection unit (22) according to claim 1, wherein the frequency lock detection unit (22) detects when the phase difference value output from the adder (41) of the phase shift unit (21) is equal to or less than a predetermined level, and sets a counter signal according to the detection result. Error detector 43 for outputting the signal to the counter, a counter 44 for counting the detection frequency of the error detector 43 according to a constant signal output from the error detector 43, and a preset reference value adder 45. The adder 45 subtracts the reference value of the reference value generator 46 from the counting value of the counter 44 and outputs the result to the multiplexer 42 of the phase shifter 21. Carrier recovery apparatus characterized in that consisting of. 제1항에 있어서, 상기 제어부(23)는 상기 위상변환부(21)의 멀티플렉서(42)를 통해 입력되는 QPSK신호의 절대 위상차(△ψ)값에서 상대적인 위상차(△ψ1)값을 검출하는 위상차 검출기(47)와, 상기 위상차 검출기(47)의 출력을 아날로그신호 즉, 일정전압레벨로 변환시키는 D/A 변환기(48)와, 상기 D/A 변환기(48)에서 출력되는 일정전압레벨의 잡음을제거하여 주파수 변환부(20)의 전압제어발진기(30)로 출력하는 루프필터(49)로 구성된 것을 특징으로 하는 반송파 복구장치.The phase difference detector of claim 1, wherein the controller 23 detects a relative phase difference value Δψ1 from an absolute phase difference value Δψ of the QPSK signal input through the multiplexer 42 of the phase shifter 21. A detector 47, a D / A converter 48 for converting the output of the phase difference detector 47 to an analog signal, that is, a constant voltage level, and noise of a constant voltage level output from the D / A converter 48. The carrier recovery device, characterized in that consisting of a loop filter 49 for outputting to the voltage controlled oscillator 30 of the frequency converter 20. ※ 참고사항 : 최초출원 내용에 의하여 공개하는 것임.※ Note: The disclosure is based on the initial application.
KR1019940034730A 1994-12-16 1994-12-16 Carrier correction system KR0132963B1 (en)

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KR1019940034730A KR0132963B1 (en) 1994-12-16 1994-12-16 Carrier correction system

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KR1019940034730A KR0132963B1 (en) 1994-12-16 1994-12-16 Carrier correction system

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KR960027863A true KR960027863A (en) 1996-07-22
KR0132963B1 KR0132963B1 (en) 1998-04-21

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100325690B1 (en) * 1999-12-03 2002-02-27 오길록 Apparatus and Method of Decision-Directed Carrier Recovery Based On LMS Method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100325690B1 (en) * 1999-12-03 2002-02-27 오길록 Apparatus and Method of Decision-Directed Carrier Recovery Based On LMS Method

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