Identification of a data stream transmitted as a sequence of packets

A method of transmitting and receiving data packets from one datastream which constitutes a given data file that is transmitted repeatedly and is time-division multiplexed with packets representing other information, comprising:

• dividing said one datastream into a sequence of file packets;
• dividing said sequence of file packets into a plurality of segments, each segment including at least one said file packet from said sequence, the file packets of a given segment being successive packets within said sequence,
• including in the first-transmitted packet of each segment a respective first series of bits containing identifying information, said first series including a given service identification portion identifying said given data file, a block number representing the position of that packet as the first-transmitted packet of that segment, a respective segment number representing the position of that segment within said plurality of segments, and a multi-bit code value which is changed whenever the data of that segment differs from the data transmitted in the previous corresponding segment,
• including in each other packet of each segment a respective second series of bits containing identifying information, said second series comprising a service identification portion the same as said given service identification portion and a respective block number representing the position of that packet within said segment, and
• transmitting said plurality of segments serially, all the respective file packets of each respective segment being transmitted prior to transmission of the first packet of the next segment transmitted.

An apparatus for receiving and processing data file packets from one datastream representing a given data file which is divided into a sequence of contents portions of file packets, some of said data file packets being transmitted repeatedly, said sequence of contents portions being divided into a plurality of segments, each segment including at least one said file packet having one said contents portion, the first-transmitted file packet of each segment containing a respective first contents portion and a respective first series of bits containing identifying information, said first series including a given service identification portion identifying said given data file, a block number representing the position of that packet as the first-transmitted packet of that segment, a respective segment number representing the position of that segment within said plurality of segments, and a multi-bit version code which is changed whenever the data of that segment differs from the data transmitted in the previous corresponding segment;

• each other packet of each segment of said datastream including a respective contents portion and one respective following-packet series of bits containing identifying information, said following-packet series comprising one said given service identification portion identifying said given data file and a respective block number representing the position of that packet within said segment, respective file packets of each respective segment being transmitted in block number order,
• said data file packets being time-division multiplexed with packets representing other information and transmitted as a bit stream,
• said apparatus comprising:
• means for receiving said bit stream,
• synchronizing and comparison means for identifying said given service identification portion of the first-received packet of said sequence of file packets,
• means, responsive to identification of said given service identification portion, for comparing the respective block number with a first value indicative of a first-transmitted packet of a segment,
• means, responsive to said block number equalling said value, for storing a second value which is at least a portion of said multi-bit version code, and for identifying subsequently received data packets of said given data file by said given service identification portion and block number only, and processing said data packets.