WO1999026339A1 - Procede et dispositif de localisation de signaux numeriques - Google Patents

Procede et dispositif de localisation de signaux numeriques Download PDF

Info

Publication number
WO1999026339A1
WO1999026339A1 PCT/US1998/024594 US9824594W WO9926339A1 WO 1999026339 A1 WO1999026339 A1 WO 1999026339A1 US 9824594 W US9824594 W US 9824594W WO 9926339 A1 WO9926339 A1 WO 9926339A1
Authority
WO
WIPO (PCT)
Prior art keywords
carrier
frequency
tuner
lock
search
Prior art date
Application number
PCT/US1998/024594
Other languages
English (en)
Inventor
Brian Crookes
Rob Strother-Stewart
Original Assignee
Scientific-Atlanta, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Scientific-Atlanta, Inc. filed Critical Scientific-Atlanta, Inc.
Publication of WO1999026339A1 publication Critical patent/WO1999026339A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
    • H03J7/02—Automatic frequency control

Definitions

  • the present invention relates to digital signal transmission and reception, and
  • the system is compatible with hardware and firmware which
  • television systems such as cable television and direct broadcast satellite (DBS) systems
  • DBS direct broadcast satellite
  • a “program” may consist of video, audio and other related
  • a cable operator may insert locally produced services at the cable-head end. The selected services
  • each subscriber is a coaxial cable distribution network.
  • each subscriber is a coaxial cable distribution network.
  • a multiplexed data stream carrying services to remote locations via, for example, a
  • the generated data stream comprises a
  • each frame comprising two fields, and each field
  • a first group of lines of a field defines a transport layer
  • a further feature of the disclosed scheme is that the data transmission rate of the
  • multiplexed data stream is related to the frequency of known analog video formats, i.e.
  • program services comprising a collection of, for example,' video, audio, teletext, closed-
  • subframe data streams are generated, each having a transport layer region and a program
  • Digital data is usually modulated onto a carrier prior to transmission.
  • video or audio may be compressed prior to modulation by well known means, such as
  • the data modulated onto the carrier must be demodulated.
  • the receiver must be tuned to the carrier frequency where the data is located, the
  • Tuner 101 receives the RF television signal. Tuner 101
  • tuner 101 has an automatic frequency control (AFC) input for adjusting the tuning of tuner 101.
  • AFC automatic frequency control
  • the AFC is used to track the QPSK carrier.
  • the output of tuner 101 is input to QPSK
  • Digital PAL Logic 104 determines whether the receiver is tuned to the QPSK carrier.
  • phase error signal is passed through the loop filter and
  • the AFC of tuner 101 is swept by the Loop Filter
  • reception equipment must be able to compensate for these wide tolerances, and a wide
  • data carrier is modulated by two different data streams that are time-division multiplexed
  • the two data streams may represent, for example, two
  • the (8/7) fraction takes into account the error correction coding added to the
  • Figure 2(a) shows the sweep of the tuner AFC for an input IF of 479.5 MHz.
  • FIG. 2(b) shows the sweep of the tuner AFC for an input IF of 482.5
  • a level circuit would then restart the sweep of the tuner AFC if a
  • the Viterbi chip and microprocessor are used to control a sweep circuit
  • Carrier lock is used as a pre-filter prior to checking
  • the system frequency plan is downloaded to further refine the search.
  • FIG. 1 is a block diagram of a carrier locating and tracking system in accordance
  • Figures 2(a) - 2(c) are graphs showing true and false lock points in sample AFC
  • Figures 3 and 4 are flow charts which illustrate the operation of the carrier
  • FIGS 5 and 6 are tables which illustrate one of different sets of various
  • the present invention provides a means for searching L-Band spectra for digital
  • present invention searches for correct carrier frequency and Forward Error Correction
  • frequency plan is downloaded to refine the search.
  • symbol rate is directly equivalent to bandwidth.
  • the present invention implements "find” and “search” modes which utilize a
  • the equipment installer can save the parameters
  • search parameters presently include FEC
  • AGC can only be tested for a value greater than the noise floor to see if
  • Carrier lock indicates that frequency
  • FEC lock will confirm that a valid
  • the detector is optimized to provide very fast carrier lockups, the detector
  • the search algorithm of the present invention can serve as a filter in the search process.
  • the search algorithm of the present invention can serve as a filter in the search process.
  • the third pass further increases time tolerances. After that, the algorithm resets to the first time tolerance on the assumption that no
  • FIGS 3 and 4 illustrate the above described operation of the search algorithm in
  • the signal lock method of the present invention represents an improvement
  • three search speeds are used to optimize the average search time.
  • the search mechanism starts the search
  • the search engine continuously cycles through the three search speeds until a valid
  • Figure 5 illustrates a matrix showing the relationships between the time allowed for carrier lock and the two parameters as follows:
  • the search engine of the present invention ignores regions with signal levels
  • search speed is determined by the number of
  • the nominal noise condition is 2.5 db above DVB noise threshold
  • digital carrier characteristics is 28 MSps, 7/8 FEC;
  • the search band is 950 MHz to 1450 MHz.

Landscapes

  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Abstract

L'invention concerne un procédé et un dispositif qui, dans un récepteur permettant de recevoir une porteuse modulée selon des données, permettent de trouver dans les spectres de bande L, les signaux numériques dans un environnement mixte de signaux numériques/analogiques. Un blocage de la porteuse intervient en préfiltrage avant toute confirmation du blocage de correction d'erreur directe. De plus, dès qu'un signal en bonne et due forme a été reçu, on télécharge le plan de fréquence du système afin d'affiner davantage la recherche.
PCT/US1998/024594 1997-11-18 1998-11-18 Procede et dispositif de localisation de signaux numeriques WO1999026339A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US97271797A 1997-11-18 1997-11-18
US08/972,717 1997-11-18

Publications (1)

Publication Number Publication Date
WO1999026339A1 true WO1999026339A1 (fr) 1999-05-27

Family

ID=25520039

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1998/024594 WO1999026339A1 (fr) 1997-11-18 1998-11-18 Procede et dispositif de localisation de signaux numeriques

Country Status (1)

Country Link
WO (1) WO1999026339A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1059729A1 (fr) * 1999-06-08 2000-12-13 Pace Micro Technology PLC Méthode et dispositif pour la recherche d'une fréquence
EP1422849A1 (fr) 2002-11-25 2004-05-26 Pace Micro Technology PLC Procédé à rechercher de signaux de porteuse modulés à données numèriques et émis par satellite

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995015640A1 (fr) * 1993-12-03 1995-06-08 Scientific-Atlanta, Inc. Procede et appareil pour localiser et suivre une porteuse a mdpk
US5528633A (en) * 1992-03-13 1996-06-18 Comstream Corporation Tuner with quadrature downconverter for pulse amplitude modulated data applications
GB2311425A (en) * 1996-03-22 1997-09-24 Digi Media Vision Ltd Demodulators

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5528633A (en) * 1992-03-13 1996-06-18 Comstream Corporation Tuner with quadrature downconverter for pulse amplitude modulated data applications
WO1995015640A1 (fr) * 1993-12-03 1995-06-08 Scientific-Atlanta, Inc. Procede et appareil pour localiser et suivre une porteuse a mdpk
GB2311425A (en) * 1996-03-22 1997-09-24 Digi Media Vision Ltd Demodulators

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1059729A1 (fr) * 1999-06-08 2000-12-13 Pace Micro Technology PLC Méthode et dispositif pour la recherche d'une fréquence
US6819731B1 (en) 1999-06-08 2004-11-16 Pace Micro Technology Plc. Frequency searching method and apparatus
EP1422849A1 (fr) 2002-11-25 2004-05-26 Pace Micro Technology PLC Procédé à rechercher de signaux de porteuse modulés à données numèriques et émis par satellite

Similar Documents

Publication Publication Date Title
US5572264A (en) High definition TV signal receiver
KR100713109B1 (ko) 디지털 변조된 무선 주파수 신호를 위한 계측용 수신기
US5235424A (en) Automatic gain control system for a high definition television signal receiver
EP0208425A2 (fr) Transmission par la sous-porteuse de signaux de télévision
US6598232B1 (en) Hybrid amplifier-regenerator for optimizing cable network transmissions
US5699385A (en) Method and apparatus for locating and tracking a QPSK carrier
US4618996A (en) Dual pilot phase lock loop for radio frequency transmission
EP0559344B1 (fr) Syntonisateur de récepteur de télévision
US6437837B1 (en) Digital broadcast signal processing apparatus and method in which channel interference by analog broadcast is prevented
EP1158676B1 (fr) Circuit pour la réduction d'interférences et récepteur de télévision
JP2003505909A (ja) ディジタル衛星放送受信機用の迅速な信号捕捉を行うチューニング・システム
JP2002512467A (ja) Ｄｂｓプロダクト用ｌｎｂドリフト・システム
US5742357A (en) Direct data tuner
WO1999026339A1 (fr) Procede et dispositif de localisation de signaux numeriques
JP4067566B2 (ja) Ｒｆ信号の同調された１つに対応する情報を伝える搬送波信号を生成するチューナおよびその制御方法
US7865135B2 (en) Apparatus for receiving satellite broadcasting and method thereof
KR100493127B1 (ko) 위성트랜스폰더의독립주파수오프셋을계산하는설비를갖는디지털위성수신기에대하여신속한포착시간을달성하는튜닝방법및그시스템
JP2000059746A (ja) Ｃａｔｖシステム及びその端末装置
US6549591B1 (en) Method and apparatus for digital interference rejection
JP3884869B2 (ja) 送信装置および受信装置
JPS6339291A (ja) 衛星放送受信機
CN1589525B (zh) 用于安装广播信道的方法和设备
KR100252936B1 (ko) 위성방송수신기의엘엔비(lnb)의국부발진주파수설정방법
JP3783704B2 (ja) 受信装置
JPH11150719A (ja) ディジタルｃａｔｖシステムとその受信装置

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
122 Ep: pct application non-entry in european phase