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    72.
    发明专利
    未知

    公开(公告)号：NO995547L

    公开(公告)日：2000-09-06

    申请号：NO995547

    申请日：1999-11-12

    Applicant: INMARSAT LTD

    Inventor： FEBVRE PAUL ,  MUDGE DAVID DENIS

    IPC: H04B7/15 ,  H04B7/185 ,  H04B7/212 ,  H04B7/26 ,  H04L24/06

    Abstract: In a bandwidth allocation protocol for a mobile communications network, the network stores associations between forward and return frequency channels, so that when a mobile receiving a forward frequency channel request return capacity, the network preferentially assigns return bandwidth to the mobile in one or more of the associated return channels.

    Satellite radiodetermination
    73.
    发明专利
    Satellite radiodetermination 未知

    公开(公告)号：GB2339098B

    公开(公告)日：2000-05-31

    申请号：GB9921828

    申请日：1995-10-24

    Applicant: INMARSAT LTD

    Inventor： KINAL GEORGE V ,  NAGLE JAMES R ,  SODDU CLAUDIO ,  RYAN FINTAN R

    IPC: G01C23/00 ,  G01S1/00 ,  G01S5/00 ,  G01S5/06 ,  G01S5/10 ,  G01S5/14 ,  G01S19/02 ,  G01S19/04 ,  G01S19/07 ,  G01S19/11 ,  G01S19/38 ,  G01S19/41 ,  G01S19/48 ,  H04B7/19

    Abstract: A satellite radiodetermination system comprises global navigation service (GNSS) satellites 2 such as GPS satellites, which generate GNSS ranging signals Rn, geostationary satellites 6 which retransmit ranging signals Rg generated at a navigation land earth station (NLES) 8, including augmentation data A, and medium earth orbit (MEO) satellites 10 which generate ranging signals Rm including regional augmentation data RA transmitted from a satellite access node (SAN) 14. The regional augmentation data RA is supplied by regional augmentation systems 21a, 21b. A navigation receiver 11 receives the ranging signals Rg, Rm, Rn and calculates ionospheric delay values for those ranging signals which are provided on dual frequencies. Using these ionospheric delay values, and optionally the regional augmentation data RA and the augmentation data A, the navigation receiver estimates ionospheric delay values for those ranging signals which are provided on single frequencies. The navigation receiver uses the ranging signals, corrected for ionospheric delay and errors indicated by the augmentation data A and regional augmentation data RA, to calculate position and time accurately.

    Communication apparatus and method
    74.
    发明专利
    Communication apparatus and method 未知

    公开(公告)号：GB0006851D0

    公开(公告)日：2000-05-10

    申请号：GB0006851

    申请日：2000-03-21

    Applicant: INMARSAT LTD

    IPC: H04J3/00 ,  H04B7/185 ,  H04B7/26 ,  H04Q7/38

    Abstract: A method of transmission in a TDMA channel comprises transmitting first communications traffic using a first TDMA protocol in first selected periods of the TDMA channel and transmitting second communications traffic using a second TDMA protocol incompatible with the first TDMA protocol in second selected periods of the TDMA channel other than said first periods.

    Data carrier deactivation in absence of user data
    75.
    发明专利
    Data carrier deactivation in absence of user data 未知

    公开(公告)号：GB2336508A8

    公开(公告)日：1999-12-07

    申请号：GB9904575

    申请日：1999-02-26

    Applicant: INMARSAT LTD

    Inventor： FELDMAN HOWARD RAY ,  WONG SIU WAH

    IPC: H04B7/185 ,  H04L12/28 ,  H04L29/06 ,  H04L29/08 ,  H04Q7/32

    Abstract: In a radio communications system in which data is transmitted on a modulated radio frequency carrier, the carrier is switched off when no data is available for transmission. If repeated signalling information is required to be transmitted, only a predetermined number of repeats are transmitted before the carrier is switched off. In one embodiment a bit sequence at the end of a first data block is compared with multiple sequences from a second block and if all sequences are equal, transmission of the second block is inhibited. In another embodiment data input for transmission is compared with a predetermined bit sequence. If a match is found for any relative bit alignment, this indicates an idle state (absence of user data) and the carrier is switched off. When more user data is received the carrier is switched on and frames are transmitted in synchronisation with the timing of frames transmitted before carrier deactivation. After carrier reactivation a constant power preamble may be transmitted to assist in level control in the transmitter. In a satellite SCPC system satellite power efficiency is improved and mobile earth station battery power is saved.

    IMAGE COMMUNICATIONS
    79.
    发明专利
    IMAGE COMMUNICATIONS 未知

    公开(公告)号：CA2471497A1

    公开(公告)日：1997-05-09

    申请号：CA2471497

    申请日：1996-11-04

    Applicant: INMARSAT LTD

    Inventor： TRACHTMAN EYAL

    IPC: H04N1/32

    Abstract: A store-and-forward image communications system for transmitting an image signal from a first terminal (24) to a second terminal (10) in one of a plurality of transmission modes which comprises: a transmission path (12, 14, 16. 18. 20) between the first and second terminals (10. 24); a first image signal interface (20) in said transmission path at which said image signal is received; a message store (116) connected to store and subsequently recall signals received at the first interface (20): a data store (302) containing at least one record (320) comprising preference data relating to preferred said transmission modes for at least one of said first and second terminals (10, 24); a transmission controller (118) selecting from said transmission control modes in accordance with said preference data; and a data updater (304) arranged to update the or each said record (320).

    Communication method and apparatus
    80.
    发明专利
    Communication method and apparatus 未知

    公开(公告)号：GB2403104B

    公开(公告)日：2006-06-14

    申请号：GB0313904

    申请日：2003-06-16

    Applicant: INMARSAT LTD

    Inventor： GRANT ALEXANDER

    IPC: H04J99/00 ,  H04B1/707

    Abstract: In a multi-user detection receiver, a multi-user detector DET receives a signal from a multiple access channel MA and the current soft estimates of each user's contribution to the received signal, and outputs updated soft estimates for each user by subtracting the current soft estimates of all the interfering users. The updated soft estimate or soft demodulated by soft demodulators DEM 1 . . . DEM K , the coded by soft decoders DEC 1 . . . DEC K which refine the probabilities of the coded bits derived from the soft demodulators DEM 1 . . . DEM K , by taking into account the knowledge of the code, and output to soft modulators M 1 . . . M K . For each iteration of the MUD receiver algorithm, an acquisition function ACQ acquires the timing of the estimates of each user's contribution to the channel for use by the detector DET in the next iteration, giving improved acquisition performance over conventional single-user techniques.

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