摘要:
A terrestrial repeater, comprising i) an interface means configured to receive a first data stream originating from a first satellite transmission network, a second data stream originating from a second transmission network, and a third data stream originating from a third terrestrial transmission network, and to transform the received streams into data packets; ii) a first processing means configured to select at least one part of the data packets of at least one of the first, second, and third streams received, and to process each selected stream portion to place the data packets it comprises into a selected broadcast format; and iii) a second processing means configured to combine the selected and processed stream portions to constitute a set of packets to be broadcast, convert the set of packets into at least one radio frequency signal, and amplify the at least one radio frequency signal in order to broadcast wirelessly towards at least one radio communication terminal.
摘要:
A terrestrial repeater (RT), comprising i) interface means (MI) having the function to receive a first data stream originating from a first satellite type transmission network (R1), a second data stream originating from a second transmission network (R2), and a third data stream originating from a third terrestrial type transmission network (R3), and to transform the said received streams into data packets; ii) first processing means (MT1) equipped to select at least one part of the data packets of at least one of the first, second, and third streams received, and to process each selected stream portion so as to place the data packets it comprises into a selected broadcasting format; and iii) second processing means (MT2) having the function to combine the stream portions selected and processed in order to constitute a set of packets to be broadcast, then to convert the said set into at least one radio frequency, and to amplify the said radiofrequency signal with a view to its broadcast via waves towards at least one radio communication terminal (UE).
摘要:
A method is devoted to synchronizing the transmission of user signals within a single-frequency hybrid network comprising at least one transmission satellite (SAT) and regenerative emitters (E1-E6) tasked with retransmitting received user signals to user terminals (T1, T2), using the same frequency and the same waveform. This method consists of temporally shifting, with respect to a time marker (TM) corresponding to the moment when a chosen element of the user signals arrives at a terrestrial reference arc (RA) from said satellite (SAT), the moment when the user signals received by each emitter (E1-E6) are retransmitted, by a local duration which is a function of the respective positions of the emitter and the satellite (SAT) with respect to a chosen reference position (RP) on said arc (RA), so that the same user signals retransmitted by the satellite (SAT) and the emitter (Ei) reach a user terminal (T1, T2) at roughly the same time.
摘要:
A method is devoted to synchronizing the transmission of user signals within a single-frequency hybrid network comprising at least one transmission satellite (SAT) and regenerative emitters (E1-E6) tasked with retransmitting received user signals to user terminals (T1, T2), using the same frequency and the same waveform. This method consists of temporally shifting, with respect to a time marker (TM) corresponding to the moment when a chosen element of the user signals arrives at a terrestrial reference arc (RA) from said satellite (SAT), the moment when the user signals received by each emitter (E1-E6) are retransmitted, by a local duration which is a function of the respective positions of the emitter and the satellite (SAT) with respect to a chosen reference position (RP) on said arc (RA), so that the same user signals retransmitted by the satellite (SAT) and the emitter (Ei) reach a user terminal (T1, T2) at roughly the same time.
摘要:
A digital data pack transmission system is especially--but not exclusiveluseful in videotex or teletext transmission (i.e. videotext or teletext data is transmitted during intervals between segments of video signals). The inventive system uses a continuous transmission carrier. A plurality of data packs are individually included in each block of data which is periodically transmitted. Dummy packs are used to fill the blocks, if less than a full complement of packs is required. The time periods available for the transmission of blocks of data are exactly equal to or a little longer than the maximum length of the transmitted blocks. The beginning of each data block has a synchronization bit pattern which is constituted by a "bit sync" byte followed by a "byte sync" byte. Except for the synchronizing pattern, the signals are scrambled before transmission and descrambled upon receipt and recognization of the data.
摘要:
This test equipment permits a testing of the demodulator of a teletex television receiver. It consists of a digital test signal generator, the output of which is connected to the HF input of the television, and a receiver, the input of which is connected to the video output of said receiver. The generator tramsmits pseudo-random data packets having a first frequency of binary elements, with two double-intervaled binary elements at two predetermined instants t.sub.1 and t.sub.2 for each packet. The receiver has a data regeneration circuit whose threshold varies line by line from a maximum value to a minimum value. The sampling clock of the receiver is at a second frequency lower than the first by the ratio (n-2)/n, where n is equal to the integral ratio of the first frequency to the line frequency of the television. A suitable means insures resynchronization of the sampling clock at the middle of each line. A receiving circuit for the pseudo-random data detects the errors which are transmitted to the video input of the television.
摘要:
According to the invention, the control messages are constituted by a general addressing message (GCM), followed by shared addressing messages (SACM). The message (GCM) contains all the information common to all the user groups and a confirmation data item of the group of users and the messages (SACM) a shared address. Thus, the group is defined in a manner inherent in the control messages and can undergo reconfiguration at any time.Application to more particularly satellite broadcasting of television programmes.