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High data rate demodulation system

A series of symbol technology, applied in the field of modulation system, can solve the problem of increased intersymbol interference

Active Publication Date: 2007-08-08
BRITISH TELECOMM PLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The bandwidth of the Gaussian filter 13 is a key parameter, if it is set smaller, the occupied bandwidth decreases, but since it sets the width of the impulse response (in terms of time), the intersymbol interference increases

Method used

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  • High data rate demodulation system
  • High data rate demodulation system
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Examples

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Embodiment Construction

[0033] Referring to FIG. 4 , where the same elements as in FIG. 3 have the same reference numerals, the comparison function 32 produces an additional output representing the difference between the selected template and the sample actually received from the reader 31 . This output is provided to an error correction processor 40 which, for a plurality of samples, generates an error correction algorithm which is used to modify the template 42 for application to subsequent samples. In this way, the stored templates tend to form a closer match over time to the actual received samples, increasing the reliability of the process.

[0034] The resulting errors are typically characteristics of the channel used to transmit the symbols, such as multipath interference caused by objects close to the receiver, co-channel interference from other transmitters, atmospheric effects, and other factors. Error correction processing enables the detector to compensate for these effects and adapt to t...

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Abstract

The demodulation process of a wireless data transmission system using multi-level symbols makes use of templates corresponding to each of the possible symbol transitions, so that knowledge of previously decoded symbols can be use to decode the next one. An estimation and correction loop provides for initial estimation of the values of a plurality of consecutive symbols, and error estimates are made for the estimated initial values of the symbols and for one or more alternative values, a final estimate being determined to minimise the total estimated error.

Description

technical field [0001] The invention relates to a modulation system suitable for radio links, especially satellite links. Background technique [0002] The aforementioned links have limited power and bandwidth, which sets an upper limit on data throughput. Bandwidth is increasingly a scarce resource, so there is often a power margin. Modern industry efforts continue to provide higher throughput rates for satellite links to reduce transmission costs. Research advances include the use of 8PSK trellis coded modems. [0003] Over the past three decades, satellite communications have become a very important part of the global telecommunications backbone. Satellite operators provide Internet Service Providers (ISPs) with long-distance point-to-point (relay) links to the Internet backbone. Currently, about 4% of satellite transponders are used for Internet relay services. While fiber-optic connections are increasingly used in mature communications markets, satellite remains th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L1/00H04L27/20H04L25/497H04L27/38H04L27/14H04L25/03
CPCH04L2025/03407H04L25/497H04L2025/03445H04L25/03012
Inventor 弗雷德里克·沃里克·迈克·斯腾蒂福特迈克尔·罗伯特·菲奇
Owner BRITISH TELECOMM PLC