EP0103380A1
Expired / Lapsed
EP
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Improvements relating to data transmission
Assignee: British Telecommunications PLC
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Filing: 1983-07-22
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Granted: —
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Expires: 2003-07-22
Abstract
Abstract A conditional replenishment video data transmission system involves the transmission of updating digital data for clusters of consecutive picture elements, all or most of which show a change since the previous frame, in lines of a raster over an image to be transmitted. The lines of the raster are numbered cyclically in groups of 8, the numbers being part of line synchronising code words, and the position along a line of the first element of each cluster is identified by a number. The data are transmitted at a constant rate from a transmitter buffer to a receiver buffer and an auxiliary data store records the addresses of the line synchronising code words in the receiver buffer. The address of the receiver buffer read by a reading means can be corrected by reference to the address data in the auxiliary storage means if for example the line numbers do not follow in sequence or the element addresses are not in ascending order due to corruption during transmission. Alternatively, the reading means may be controlled at all times by the address data in the auxiliary storage means and not only when a tracking error has occurred. The tracking of the received data in the receiver buffer by the reading means may show a consistent error relative to the position predicted by the assumed transmission delay time; preferably such tracking errors are corrected by a whole frame jump using a receiver buffer of more than one frame capacity.
Inventors
- 👤 Craig Shawn Kenton Clapp
- 👤 Norman Leonard Shilston
- 👤 Jean-Claud Rene Jolivet
- 👤 Daniel Pierre Devimeux
- 👤 Armand Riou
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 02:58
CPC Classifications
H; H04; H04N; H04N21/00; H04N21/40; H04N21/43; H04N21/44; H04N21/44004; H04N19/00; H04N19/10; H04N19/134; H04N19/146; H04N19/152; H04N19/50; H04N19/503; H04N21/4302
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
147 words
A digital data transmission system having'a source of data at an uneven rate, the data including a plurality of marker signals, a first buffer store for the data from the source, means for transmitting the data from the first buffer store at a constant rate to a transmission path, means for receiving the data from the transmission path and applying them to a second buffer store, means for reading the data from the second buffer store at an uneven rate, and a utilisation means using the data from the second buffer store, wherein the receiving means includes auxiliary data storage means, means for storing in the auxiliary data storage means the addresses of the second buffer store in which the marker signals are stored, and means for determining the address used by the reading means by reference to the addresses stored in the auxiliary data storage means.
Claim 2
Dependent Claim
147 words
A digital data transmission system having'a source of data at an uneven rate, the data including a plurality of marker signals, a first buffer store for the data from the source, means for transmitting the data from the first buffer store at a constant rate to a transmission path, means for receiving the data from the transmission path and applying them to a second buffer store, means for reading the data from the second buffer store at an uneven rate, and a utilisation means using the data from the second buffer store, wherein the receiving means includes auxiliary data storage means, means for storing in the auxiliary data storage means the addresses of the second buffer store in which the marker signals are stored, and means for determining the address used by the reading means by reference to the addresses stored in the auxiliary data storage means.
Claim 3
Dependent Claim
16 words
A system according to claim 1 wherein the marker signals include numbers following a predetermined cycle.
Claim 4
Dependent Claim
36 words
A system according to claim 1 or 2 wherein the addresses of all marker signals are transferred from the auxiliary data storage means to the reading means to control the addresses used by the reading means.
Claim 5
Dependent Claim
46 words
A system according to claim 2 wherein the receiving means includes means for detecting when the reading means is apparently reading data from an incorrect address of the second buffer store and for correcting that address from the information stored in the auxiliary data storage means.
Claim 6
Dependent Claim
32 words
A system according to claim 4 wherein the detecting and correcting means responds to the numbers in the marker signals in the received data before being entered in the second buffer store.
Claim 7
Dependent Claim
86 words
A system according to claim 3 or 5 wherein the receiving means includes counting means for following the predetermined cycle of the numbers in the marker signals and means for comparing the marker signal number recorded by the counting means with the number in the marker signal being received at the time, a non-zero output of the comparing means providing an indication that-a marker signal had been corrupted so as not to be recognised and that the address used by the reading means should be corrected.
Claim 8
Dependent Claim
46 words
A system according to claim 6 wherein the data also includes other marker signals and the receiving means includes means for predicting the times of occurrence of such other marker signals by reference to the position of the received marker signal numbers in the predetermined cycle.
Claim 9
Independent Claim
59 words
A system according to any of claims 1 to 6 wherein the data are conditional replenishment data for an image and the marker signals are line synchronisation code words with line number information, wherein the data represent picture elements along a line at which changes are to be made, the changes being formed into clusters relating to consecutive elements.
Claim 10
Dependent Claim
46 words
A system according to claim 8 wherein the data also include field synchronisation code words and the receiving means includes time base means for predicting the time of reception of field synchronsiation code words by reference to the line numbers in the line synchronisation code words.
Claim 11
Dependent Claim
38 words
A system according to claim 9 and including the features of claim 6 wherein the counting means tracks the line numbers and is reset to a datum value in response to an output from the time base means.
Claim 12
Independent Claim
70 words
A system according to any of claims 8 to 10 wherein the data includes for each cluster the element address along the line of the first element in the cluster, and the receiving means includes means for checking that the element addresses of clusters between consecutive line synchronising code words occur in ascending numerical order thereby to detect whether a corrupted, and therefore unrecognised, line synchronising code word has occurred.
Claim 13
Independent Claim
83 words
A system according to any of claims 8 to 11 wherein the receving means includes means responsive to the quantities of data in the first and second buffer stores to calculate whether the actual quantity of data in the second buffer store differs consistently from the quantity expected to be in that store on the assumption of a particular propagation delay time for the transmission path, the reading means being adjusted to tend to correct any consistent difference found by the responsive means.
Claim 14
Dependent Claim
38 words
A system according to claim 12 wherein the second buffer store can store more than a complete video frame period of data and the adjustments to the reading means involve discarding or repeating an entire frame of data.
References Cited (Backward Citations)
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