Facsimile and static presentation processing – Facsimile – Auxiliary signal
Patent
1995-12-22
1998-06-23
Vu, Kim Yen
Facsimile and static presentation processing
Facsimile
Auxiliary signal
358426, 3582611, 341 52, H04N 1415, H03M 1302
Patent
active
057711020
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is directed to a process for the transmission of images in which data are generated by at least one data source, are inserted in a data frame at a channel coder and are subjected to a channel coding. A process for the transmission of images is described in Biere, "Ubertragung von Bewegt- und Standbildern in stark gestorten schmalbandigen Kanalen narrow-band fax telephone channels with high interference!", Bosch Technische Berichte, No. 54, 1991, in which the image data of an image undergo a source coding and the source-coded image data are then channel-coded and transmitted via a data channel. The source coding is effected in the form of a predictive error coding and a block-oriented movement estimation. A rate-compatible punctured convolutional code (RCPC) is used for channel coding, the occurring data streams being punctured and subsequently interleaved to form a common data stream.
SUMMARY OF THE INVENTION
The process according to the invention enables various kinds of data to be channel-coded and transmitted at various code rates. Information about the code rate and the class type is advantageously stored in an information word. This enables an efficient dividing up of the available data rates.
In a particularly advantageous manner, information about the type of data generation is transmitted itself as data of a class. In particular, image data, audio data, facsimile data, and data in the form of data files are transmitted. The channel error protection is improved by using an interleaving method. By forming a data frame with multiple whole-number storage locations to be found in a diagonal of a memory matrix, it is possible to find the synchronizing word quickly by means of the data interleaving method and to carry out an accurate synchronization of the deinterleaver and data frame.
Instead of code information, additional data is advantageously entered in the information word. Accordingly, data can be exchanged from the channel coder to the channel decoder without having to change the data protocol. A Viterbi decoder which operates according to the Maximum Sequence Estimation process is particularly suitable for channel decoding.
The process according to the invention for transmitting image data has the advantage over the prior art that the source-coded data are divided into classes, these classes indicating, e.g., the sensitivity of the source-coded image data to transmission errors and are coded with different code rates according to the extent of the error protection. These classes are provided with varying degrees of error protection depending on sensitivity, the sensitive image data receiving greater error protection than the less sensitive image data. In this way, the available data rate is used more efficiently. Accordingly, it is possible to improve image quality at the same data rate. The division of the image data into classes and the length of the classes and error protection used are transmitted by way of a first information word so that these data which are required for decoding are transmitted also and made available to the decoder. Data relating to the source coding are preferably included in the transmission in the form of code words. A second information word is used to identify the length of the code words, the class of the code words, and the error protection of the code words. In this way, additional information is made available for the source decoding. The quality of the source-decoded image data is accordingly improved.
Further embodiments of the preferred process provide additional improvements over the prior art. In a particularly advantageous manner, a synchronizing word composed of two Williard code words or two Barker code words is used for synchronization. The synchronizing word is added to the image data in a fixed pattern as a pseudo-noise (PN) synchronizing word. This enables a simple and accurate synchronization with sufficient protection against transmission errors.
The information word or the first and second information w
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Bosch Technische Berichte, No. 54, 1991, "Uebertragung von Bewegt-und Standbildern . . . ", Dietmar BIERE (No Translation).
Lappe Dirk
Mann Pelz Rodolfo
Mundt Frieder
Nitsche Gunnar
Vogt Oliver
Nguyen Madeleine A-V
Robert & Bosch GmbH
Striker Michael J.
Vu Kim Yen
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