Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1996-12-12
2001-04-17
Nguyen, Chau (Department: 2663)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S540000
Reexamination Certificate
active
06219357
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an art of channel multiplex transmission by which a plurality of channels are multiplexed and transmitted, and particularly, to an art of channel multiplex demultiplex in a system for selecting particular data that have been received after multiplexing and transmission of a plurality of data.
Publication of JP-A-218233/1989 has disclosed a construction shown in
FIG. 9
as a conventional channel multiplex demultiplex unit of the above-described type. It is assumed that 4 channels are multiplexed. Referring to
FIG. 9
, a transmission unit
108
at a transmission side combines an 8 bit parallel video signal
101
and a 1 bit serial frame signal
103
at each bit parallel into one channel signal. Then the resultant 9 bit parallel signal is converted into 10 bit parallel signal by a
9
B
10
B coding circuit
102
.
A frame signal generator
104
for generating a frame signal
103
is provided for each channel. The frame signal
103
has a common frame pattern containing a data signal.
The frame signal
103
is used for synchronization as well as for identification of each channel.
The 10 bit parallel signal of a channel output from the
9
B
10
B encoder
102
is converted into a serial signal by 10:1 parallel/serial conversion circuit
105
. The converted serial signal is further multiplexed among channels by 4:1 parallel/serial conversion circuit
106
and then input to a transmitter
107
from which the resultant transmission signal is sent to a transmission path. In a reception unit
11
b,
a receiver
109
receives the transmission signal, which is shifted to a serial/parallel conversion circuit
110
by a clock signal output from a hunting circuit
115
. The 10 bit parallel signal corresponding to each channel is sequentially input to
10
B
9
B decoder
111
corresponding to the channel.
A 9 bit parallel signal output from the
10
B
9
B decoder
111
is separated into an 8 bit parallel video signal and a 1 bit frame signal. The frame signal of each channel is input to a corresponding synchronous detection circuit
112
and subjected to frame detection. The synchronous detection circuit
112
compares, for example, an input bit sequence (9 bit) with a predetermined synchronous pattern. When those patterns accord with each other, a synchronous detection signal is output. When the synchronous pattern is not detected, a report of detecting no synchronous pattern is sent to a synchronous protection circuit
114
.
Among signals output from each synchronous detection circuit
112
, those signals selected by a channel selection circuit
113
are input to the synchronous protection circuit
114
for frame synchronization.
When the frame synchronization is not executed in the synchronous protection circuit
114
, the hunting circuit
115
shifts a phase of the clock driving the serial/parallel conversion circuit
110
by a predetermined amount. This operation is continued until the 10 bit parallel signal output from the serial/parallel conversion circuit
110
corresponds to each channel.
As aforementioned, in the conventional transmission system through channel multiplexing, 1 bit frame signal is added accompanied with a byte parallel signal of the data. The resultant coded byte becomes irregular, thus requiring its own coding.
As the decoded frame signal is serial, the frame signal is parallel converted and bit rotated (shifting the bit location in a cyclic manner, for example, inserted from LSB (low-order bit) overflowing from the MSB (high-order bit) side by the synchronous detection circuit at a reception side for comparing the bit pattern. The processing until detection of synchronization takes much time as well as requiring double bit rotate function (
10
B
9
B decoding and frame signal extraction in pattern detection for synchronous detection).
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the aforementioned problems.
It is another object of the present invention to provide a channel multiplex demultiplex method allowing for channel selection with a simple circuit construction using a coding method in order to realize a stable circuit operation in a channel multiplex demultiplex unit for multiplexing and transmitting a channel.
The above object of the present invention is achieved by a channel multiplex demultiplex method for multiplexing and demultiplexing a plurality of channels comprising steps of: coding each channel using a coding method coding m bits to n bits (each m, n is predetermined integer but m<n) and setting n bits as 1 byte, inserting into each channel at least one bits string of n bit that has not been used for coding said m bits to said n bits as a channel identification byte for channel identification into each channel and multiplexing a plurality of channels; and identifying each channel from data in which a plurality of channels are multiplexed based on said channel identification byte.
The object of the present invention is achieved by a channel multiplex demultiplex method for multiplexing and demultiplexing a plurality of channels comprising steps of: coding each channel using a coding method coding m bits to n bits (each m, n is predetermined integer but m<n) and setting n bits as 1 byte; inserting at least one bits string of n bits that has not been used for coding said m bits to said n bits as a channel identification byte for identifying each channel into each channel; multiplexing channels to which said channel identification byte is inserted; and identifying each channel from data in which a plurality of channels are multiplexed based on said channel identification byte.
The object of the present invention is achieved by a channel multiplex demultiplex method for multiplexing and demultiplexing a plurality of channels comprising steps of: inserting identification data into each channel for channel identification; multiplexing a plurality of channels to which said identification data are inserted; coding data in which a plurality of channels are multiplexed using a coding method coding m bits to n bits (each m, n is predetermined integer but m<n) and setting n bits as 1 byte and converting said identification data into 1 byte channel identification byte containing bits strings of n bits that has not been used for coding said m bits to said n bits; and identifying each channel from data in which a plurality of channels are multiplexed based on said channel identification byte.
The object of the present invention is further achieved by a channel multiplex demultiplex unit for multiplexing and demultiplexing a plurality of channels comprising: a multiplex circuit for coding each channel using a coding method coding m bits to n bits (each m, n is predetermined integer but m<n) and setting n bits as 1 byte, inserting at least one bits string of n bits that has not been used for coding said m bits to said n bits as a channel identification byte for channel identification and byte synchronization into each channel and multiplexing a plurality of channels; and a demultiplex circuit for identifying each channel from data in which a plurality of channels are multiplexed based on said channel identification byte and demultiplexing each channel.
The characteristic of the present invention is coding data of a channel using a coding method for coding m bits to n bits (each m, n is predetermined integer but m<n) setting the n bits as 1 byte. The n bits string that has not been used for coding the m bits to n bits is used as an identification byte for identifying the channel and as characters for byte synchronization.
Assuming that 1 bits is coded to 2 bits, the 1 bits takes the bits string either 0 or 1. The 2 bits takes the bits string 00, 01, 10 or 11. For example, when coding the 1 bits string “0” to the 2 bits string “00” and coding the 1 bits string “1” to the 2 bits string “01”, those 2 bit strings “10” and “11” cannot be used for coding. Therefore those 2 bits strings “10” and “11” can be used as identification bytes for channel identification and as characters
Boakye Alexander
NEC Corporation
Nguyen Chau
Scully Scott Murphy & Presser
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