Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
2000-02-10
2003-04-08
Diep, Nhon (Department: 2713)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C375S240280
Reexamination Certificate
active
06546054
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video transmission system using plural links and, more particularly, to a video transmission system using plural links suitable for transmitting compressed video signals.
2. Description of the Related Art
Multiple video transmission through different links has been conventionally used for enhancing reliability of transmission. One example of such conventional transmission will be described below in reference to FIG.
6
.
FIG. 6
illustrates a duplex video transmission using regular and backup links. An input video signal
40
is distributed to two links by a distributor
41
. In the case of digital compression coding transmission, encoders
42
and
44
for video signal compression and decoders
43
and
45
are used in the two links, respectively. Assuming that the link consisting of the encoder
42
and the decoder
43
is referred to as a regular link and the link consisting of the encoder
44
and the decoder
45
is referred to as a backup link, a switcher
46
selects the regular link at the time of normal transmission, to output an output video signal
47
. To the contrary, in the case where an accident occurs on the regular link, the switcher
46
immediately switches the transmission link to the backup link, to thus output an output video signal
47
.
In this way, the above-described duplex video transmission using the regular and backup links can ensure the high reliability of the video signal transmission.
However, the above-described duplex video transmission using the regular and backup links has raised a problem that the transmission links are used with low efficiency since the backup link is not used at all during the normal transmission which accounts for most of the transmission period of time.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a video transmission system using plural links in which the transmission capacity of a backup link can be effectively used while high reliability of transmission can be ensured.
The first aspect of the invention lies in that a video transmission system using plural links for transmitting video signals over the plural links comprises means for distributing an input video signal to the plural links, and processing means for coding the video signals distributed to the links in such a manner as to shift them from each other at least either spacewise or timewise.
The second aspect of the invention lies in that a video transmission system using plural links for transmitting video signals over the plural links comprises decoding means for decoding the coded video signals transmitted over the plural links, synthesizing means for synthesizing the video signals from the plural links decoded by said decoding means, the video signals being shifted from each other at least either spacewise or timewise, and output selecting means for selectively outputting the decoded outputs on the links and an output from said synthesizing means, said output selecting means selecting the output from said synthesizing means when the plural links are operated normally while selecting the decoded output on the normal link in the case where abnormality occurs on any one of the plural links.
The third aspect of the invention lies in that a video transmission system using plural links for transmitting video signals over the plural links comprises means for distributing an input video signal to the plural links, processing means for coding the video signals distributed to the links in such a manner as to shift them from each other at least either spacewise or timewise, decoding means for decoding the coded video signals transmitted over the plural links, synthesizing means for synthesizing the video signals from the plural links decoded by said decoding means, the video signals being shifted from each other at least either spacewise or timewise, and output selecting means for selectively outputting the decoded outputs on the links and an output from said synthesizing means, said output selecting means selecting the output from said synthesizing means when the plural links are operated normally while selecting the decoded output on the normal link in the case where abnormality occurs on any one of the plural links.
According to the present invention, the video signals on the links are coded in such a manner as to be shifted from each other at least either spacewise or timewise, so that the video signals transmitted over the plural links are synthesized, thereby obtaining the output video signal similar to the original video signal. Furthermore, it is possible to obtain a normal video signal also over a single link.
REFERENCES:
patent: 5539726 (1996-07-01), Mizusawa
patent: 5680389 (1997-10-01), Douglas et al.
patent: 6052210 (2000-04-01), Nathan
Hamada Takahiro
Kawada Ryoichi
Matsumoto Shuichi
Diep Nhon
KDD Corporation
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