One way data transmission system
First Claim
1. An one-way data transmission system whereinthe transmitter station transmits data in the form of data packs, from a plurality of channels, the data packs from said plurality of channels are time multiplexed, each data pack comprises a prefix coded signal, in addition to the conventional synchronization and service signals, whereinone channel amongst the plurality of channels is allotted to the transmission of a date information, each receiver equipment comprising means for comparing each pack prefix code with a channel code stored in a dead memory,each dead memory containing in addition to the channel code, a subscription period information, said receiver equipment comprising means for receiving the date channel information from the date channel and comparing said date channel information with the subscription period information stored in the dead memory and which, when the comparison result is positive, delivers a first validation signal, andsaid means for comparing the prefix code to the dead memory channel code and delivering a second validation signal when the second comparison result is positive,the first and second validation signals being combined for validating the received pack having caused the second validation signal.
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Abstract
There is provided a one-way data transmission system wherein a transmitter station transmits in the form of data packs data from a plurality of channels, the said packs being time multiplexed.
One channel amongst the plurality of channels is allotted to transmitting date information. In the receiver equipments, the dead memory stores not only the channel code, but also a subscription period information which permits to validate the channel code depending on the date information received from the date channel. Automatic dead-memory distributors are provided which receive data from a control channel transmitted by the system, like other channels. The system is compatible with television systems.
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Citations
8 Claims
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1. An one-way data transmission system wherein
the transmitter station transmits data in the form of data packs, from a plurality of channels, the data packs from said plurality of channels are time multiplexed, each data pack comprises a prefix coded signal, in addition to the conventional synchronization and service signals, wherein one channel amongst the plurality of channels is allotted to the transmission of a date information, each receiver equipment comprising means for comparing each pack prefix code with a channel code stored in a dead memory, each dead memory containing in addition to the channel code, a subscription period information, said receiver equipment comprising means for receiving the date channel information from the date channel and comparing said date channel information with the subscription period information stored in the dead memory and which, when the comparison result is positive, delivers a first validation signal, and said means for comparing the prefix code to the dead memory channel code and delivering a second validation signal when the second comparison result is positive, the first and second validation signals being combined for validating the received pack having caused the second validation signal.
Specification