SYSTEME D'INFORMATION A LARGE BANDE POUR SERVICES DE DISTRIBUTION ET SERVICES INTERACTIFS

WIDE-BAND INFORMATION SYSTEM FOR DISTRIBUTION SERVICES AND INTERACTIVE SERVICES

Abrégé anglais

A wide-band information system for distribution services
and interactive services is being proposed that possesses
an information center (6) and a wide-band network (5) as
well as a converter with at least one coaxial network
whereby the data are transmitted digitally for the
wide-band network and whereby, for modulating and digitizing the
channels in the information center, a separate digitizer is
present for each channel and whereby the digitized channels
are integrated via a multiplexes (8) into one digital data
stream.

Revendications

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WHAT IS CLAIMED IS:
1. Wide-band information system for distribution services
and interactive services with an information center (6) and
a wide-band network (5) as well as a converter unit (13) on
which at least one coaxial network (12) is connected,
whereby data are transmitted digitally over the wide-band
network (5), characterized in that for modulation and
digitalization of the channels in the information center
(6) for every channel (D1-Dn) a separate D-S modulator (4)
is present, and in that the digitized channels are brought
together with a mulitplexer (8) for digital data streaming.
2. Wide-band information system for distribution service
as under claim 1, characterized in that the data stream in
the converter unit (13) runs through a demultiplexer (9), a
digital up-converter (10), and a digital/analog changer
(11) for recovery of the individual VHF/UHF channels.
3. Wide-band information system for distribution services
as under claim 1 or claim 2, characterized in that in the
converter unit (13) all recovered channels run through an
adder (3) and are added to a UHF/VHF channel mixture.
4. Wide-band information system for distribution services
under one of the preceding claims characterized in that the
wide-band transmission network (5) is a SDH/SONET ADM
transportation system.

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5. Wide-band information system for distribution services
under one of the preceding claims characterized in that the
demodulation in the converter units takes place with
delta/sigma demodulators.

Description

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Wide-band information system for distribution services
and interactive services
The invention proceeds from a wide-band information system
for distribution services and interactive services of the
sort of the primary claim.
From DE-OS 44 35 767, a wide-band information system is
known whereby data are transmitted in both analog and
digital ways. Today, there are already numerous
participants connected over coaxial networks with
television stations or other services. Over these networks,
pay-on-demand television can be developed in a simple form
in addition to reception of cable television programs,
however without having to interact with the broadcasting
source. In the future, video on demand with direct access
to video databases will be possible. The wide-band networks
that [sic] the connection between information centers and
converter units that produce the connection to individual
participants are being increasingly expanded with fiber
optic cable. In the end, however, when using the converter
unit, signals must be transferred onto a coaxial network.
In general, the use of coaxial cables as a medium for
transmitting television and sound signals up to a frequency
of ca. 1 GHz and for the analog transmission of television
and sound signals is possible in a range from 47 MHz to 450
MHz. In order to optimize transmission over optical wide-
band networks, data from individual channels are today
transmitted digitally.

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Here, individual channels are modulated, subject to an up-
conversion, added, and finally delta/sigma-modulated. In
this way, a single data stream is created that exhibits a
mixture of the different original channels and with which
it is no longer possible to influence the individual
channels. In the converter unit, there is only one common
modulation possible in order then to finally execute
conventional channel processing.
The wide-band transmission system relating to the invention
with the characteristic properties of the primary claim has
the additional advantage that the individual channels in
the information center are delta/sigma-modulated separately
from each other and that only at the end are the digitized
and modulated channels integrated within an appropriate
multiplexer into a single digital data stream. This way,
one obtains digitized data that can be distributed over
existing high-bit transmission systems and can be used in
data formats such as SDH/SONET/ADM. This way, it is
possible to select individual data packages in the
converter unit, and it is no longer necessary to always
demodulate the common data stream in each converter unit.
Through the measures detailed in the sub-claims,
advantageous extensions and improvements of the wide-band
transmission system indicated in the main claim are
possible. Particularly advantageous is that, within the
converter unit, channels can be selectively recovered by
implementing a demultiplexer, a digital up-converter, and a
digital/analog transformer for recovering individual
channels. Through control in the converter unit, either a

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complete recovery of a11 fed-in data channels or selective
recovery is then possible.
Advantageously, an SDH transportation system is used as a
wide-band transmission network whereby multiplexers and
demultiplexers have to be adapted in the system to the SDH
protocol. Through use of this known protocol, targeted
access to data channels is possible and simple. The system
makes possible through its routing functions this access.
Advantageously, in the system simple delta/sigma modulators
and demodulators for modulating and demodulating digital
signals are used.
An example of execution of the invention is depicted in the
figure and explained in more detail in the following
description. It shows in figure 1 the state of the
technology in an information center; in figure 2 the
construction of the information center relating to the
invention; and in figure 3 the construction of a converter
unit relating to the invention.
The data of the television channels (D1-Dn) are fed into a
modulator (1) in the information center (6). The modulator
(1) is tied respectively with an up-converter (2). The
output of the up-converter (2) is connected with the input
of an adder (3) whose output is again connected with a
delta/sigma modulator (4). The output of the D-S modulator
(4) is connected to the wide-band transmission network (5).
The data (D1-Dn) are modulated next in the information
center. Here, each form of modulation is possible, e.g. a

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QPSK modulation or the different forms of QAM modulation.
The modulated data stream is transferred within the up-
converter onto the carrier frequency that is located in the
band below 450 MHz. This modulated data stream runs through
the adder ( 3 ) in which the totality of all data streams is
integrated into a channel mixture in the UHF frequency
band. The UHF channel frequency runs through a D-S
modulator and has to be reset with large data rates, in
general greater than 2.5 Gbit/sec. This data stream is
transmitted over the wide-band network (5). On the
converter unit side is the demodulation that again
recovered a UHF channel mixture and fed into the coaxial
network.
The system relating to the invention is depicted on
broadcaster page 2 in the figure. The data stream (D1-Dn)
again enters into a modulator (1). The output of the
modulator (1) is connected respectively with a D-S
modulator (7) whose output connects at the input of a
multiplexes (8). The multiplexes (8) is connected at the
output with the wide-band transmission network (5). The
entering digital video data streams are modulated in the
modulators (1). Here, each form of modulation is possible.
The combination of quite different modulation processes is
also possible in the modulator (1) for the respective data
streams. The modulated HF signals indicate then a frequency
clearly less than 100 MHz. These signals are fed into the
digital modulator (7) that modulates the signals whereby
the modulation takes place on the basis of timing signals
that the multiplexes (8) provides to the individual
modulators. The timing signals are different than the

CA 02257571 1999-O1-18
individual modulators (7), but they all indicate the same
frequency. At the output of the modulator (7), there is for
each channel an individually modulated data channel. This
resulting data stream (D) possesses data rates from a few
100 Mbit and is fed into the multiplexer (8). The
multiplexer resets the individual channels into a common
data stream (C) that are the Gbit/sec., for example, and is
fed into a wide-band transmission network (5). Here, the
multiplexer adds information signals that enables routing
functions within a certain protocol, e.g. SDH. Fed into the
wide-band network, individual data channels can be further
processed in accordance with the defaults of the network.
Figure 3 shows a converter (13) where the resetting of the
wide-band network (5) takes places into the coaxial network
(12). The converter (13) indicates at input a demultiplexer
(9). The outputs of the demulitplexer (9) are connected
with a digital up-converter (10) this is connected again
with a digital/analog transformer (11). The output of the
transformer (11) lies at the entrance of an adder (3) whose
exit is tied with a coaxial network (12).
The incoming data stream (C) is recovered again into
individual data streams (D) within the demultiplexer (9).
The individual data streams (D) assigned to a digitized
data channel pass through a digital up-converter (10) such
that each exiting data stream (E) obtains the assignment to
a sub-carrier channel with a certain channel frequency in
the VHF/UHF band. The demodulation takes place in the
demodulator (11) by recovering the data in an analog
fashion. The carrier frequency of each channel (G) is

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determined by an individual signal (F) that initializes the
digital up-converter. Finally, a11 analog channels are
added and the mixed signature fed into the coaxial network.
The transformers used in the wide-band transmission system
in the [sic] are in the simplest case delta/sigma
modulators and/or demodulators as these can be procured
without great expense. In particular in the information
centers (6), a whole array of modulators (4) become
necessary as each channel indicates a specific
digitalization. Thus, the implementation of the simple
delta/sigma modulators leads to no great cost. Also in the
converter (6), simple delta/sigma demodulators can be
simply implemented and even here at no great cost
requirement for the system. A great advantage of the
suggested wide-band transmission system is that the used
modulators can work with narrow bit rates and thus can be
easily expanded. In the state of the technology, a
digitizer that has to work at great expense with high data
rates is being implemented. It is of further advantage that
each channel can be managed individually and that out of
the mixture of the channels an individual integration of
channels is [sic] for each coaxial network. Even the
adaptation of recently fed-in data to such a network is
possible without problems.

Dessin représentatif