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FIELD OF THE INVENTION
The present invention relates in general to digital, interactive
communication systems, capable of transmitting at a subscriber's request
still-television video frames, possibly with an accompanying audio
message, and more particularly to a presentation player which receives a
stream of digital packets through a standard CATV distribution trunk,
converts the digital packets into the selected video presentation with
accompanying audio and transmits such presentation to the requesting
subscriber on a pre-assigned output channel within a standard CATV
distribution feeder.
BACKGROUND OF THE INVENTION
Conventionally, different kinds of communication systems are used to
provide voice, data, and video communication services to subscribers. In
particular, interactive cable television systems have been developed to
distribute information to subscriber's televisions at their requests. One
such system concerns a shopping service where subscribers shop at home in
an "electronic mall". This system is distinguished from home shopping
channels since it allows subscribers to select which products or services
they will view on their television screens by use of in-house subscriber
apparatus, such as telephones or CATV key pads. In operation, the
subscriber tunes to a channel and requests connection to a remote location
by dialing a predetermined telephone number, or accesses via a CATV
reverse channel. As soon as the system identifies the subscriber, his
television screen begins to display still-frame video, and possibly
accompanying audio, and directories of "electronic stores" comprising
products or services that may be entered or passed, examined in further
detail, saved for future consideration, or purchased just by touching keys
on a touch-tone telephone in response to prompts on the television screen.
A main-frame host computer controls the flow of information in the system.
This shopping service uses a CATV network to distribute the video
presentations and accompanying audio messages requested by subscribers. At
various locations in the CATV network, a device known as a frame store
unit captures the video and audio portions of a presentation. Each of
these locations serves a small group of subscribers. The function of each
frame store unit is to capture the video frames destined for subscribers
assigned to the particular frame store unit. The frame store unit captures
a video frame bearing the address of an assigned subscriber and converts
the frame into a form it can store. Next, the frame store unit determines
which audio message to associated with the video frame, bundles the audio
and video together by time multiplexing the video on one channel and
frequency multiplexing the audio on another channel, and then injects the
result into he CATV feeder cable. The composite signal transmitted by the
frame store unit appears as a standard television picture on the
subscriber's television.
The audio and video signals processed by the frame store unit are in analog
format. This is in sharp contrast to the presentation player of the
present invention which receives and processes both the video and audio
portions of a presentation in digital format. Moreover, the presentation
player time multiplexes both the video and audio on a single channel.
The advantages of the presentation player over the frame store unit are
numerous. The presentation player makes it possible for the interactive
communication system to service more subscribers than the prior system
because both the audio and video signals are time multiplexed on one
channel. Moreover, the digital processing of these signals results in
improved distortion immunity, improved audio fidelity, and an improved
capability to maintain the integrity of the video portion of a
presentation. An additional advantage of digital processing is an increase
in the portion of the CATV frequency spectrum usable for transmission of
the proposed audio/video service.
Thus, the digital processing and time multiplexing of both audio and video
by the presentation player offers significant advantages over the frame
store unit used in other interactive communication systems.
SUMMARY OF THE INVENTION
An objective of the present invention is to overcome the deficiencies of
the prior art noted above by providing a presentation player which can be
utilized in a digital, interactive communication system capable of
transmitting to subscribers television quality, still-video and
motion-video presentations with accompanying audio.
It is another object of the presentation player of the present invention to
process both video and audio signals in a digital format and thereby
provide a more accurate reproduction of the original signals.
It is a further object of the present invention to operate the presentation
player as part of a new and improved interactive communication systems for
merchandising products and services to subscribers.
The present invention is directed to a presentation player used in an
interactive communication system wherein subscribers select from a
plurality of video/audio presentations for viewing on their television
sets. The video/audio presentations are transmitted in the form of digital
packets of information to a plurality of presentation players
strategically located in the vicinity of the subscriber. Each of the
digitized packets transmitted to the presentation players is uniquely
addressed to a requesting subscriber.
The presentation player includes a converter, a controller, and at least
one subscriber server. The converter is tuned to a fixed-frequency,
narrow-band control channel which broadcasts tuning information. This
tuning information causes the converter to tune to a broadband channel
where it monitors a digital stream of information including the digital
packets representative of selected video/audio presentations. The
converter also detects for further processing the digital packets uniquely
addressed to predetermined ones of the requesting subscribers.
The controller means receives the uniquely addressed digital packets from
the converter and transmits each of these packets to a pre-assigned
subscriber server according to the packets unique address. That is, each
presentation player processes the digital packets addressed to specific
subscribers. More specifically, each subscriber server within a
presentation player is in turn responsible for processing the digital
packets of certain subscribers. The subscriber server receives the digital
packets, converts them into analog formatted (conventional NTSC)
video/audio presentations which are then transmitted to the requesting
subscriber.
BRIEF DESCRIPTION OF THE DRAWING
For a fuller understanding of the nature and objects of the invention,
reference should be made to following detailed description, taken in
connection with the accompanying drawings.
FIG. 1 is a block diagram of a digital, interactive communication system
which in conjunction with a CATV network and the presentation player of
the present invention provides subscribers with television quality,
still-video presentations.
FIG. 2 is an exploded block diagram of the presentation player show in FIG.
1.
FIG. 3 is an exploded block diagram of the presentation player converter
shown in FIG. 2.
FIG. 4 is an exploded block diagram of the subscriber server shown in FIG.
2.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, the presentation player of the present invention is
utilized in conjunction with a digital, interactive cable television
system generally designated as 10. In the operation of system 10, a
subscriber uses a Touch-Tone telephone 12 to communicate with the system
10. The transmission signal sent through telephone 12 are carried over
conventional telephone lines to a Local Operating Center ("LOC") 11 of the
system 10, which makes use of local area network technology. At the LOC
11, the tone-signals of telephone 12 are received by a voice network
interface ("VNI") 14. If the tone-signals are conventional voice grade
transmissions, they are transmitted to VNI 14 in analog format and are
recognized and decoded by VNI 14 to ACII characters recognized by an
interface 16. In the instance where the tone-signals are received by NVI
14 as digital signals, VNI 14 likewise transforms the digitized Touch-Tone
signals into protocol recognized by interface 16. VNI 14 could be a Summa
Four, Inc., Specialty Digital Switch Model No. SDS-1000 having a
predetermined number of outgoing telephone lines for bridging incoming
subscriber calls to service representatives when required. Notwithstanding
whether the tone-signals are in digital or analog form, the output signal
of VNI 14 is transmitted to a first local area network ("LAN") 18 via the
interface 16. While VNI 14 is shown in FIG. 1 as being located at the LOC
11, it is anticipated by the present invention that VNI 14 need not be
co-located at the same location as LOC 11.
The network topology of first LAN 18, that is the physical organization of
the network, is known as a ring topology. A ring topology has all devices
in the network connected by a single communications cable that forms a
circle or ring. Signals are sent from one device to another around the
ring. As a signal moves around the ring, each device in the LAN
electronically detects whether the message if for it. If it is, the device
processes the signal. If not, the device will normally regenerate the
signal and transmit it to the next device in the ring.
Network access identifies the procedures that allow each device in the
network to communicate and receive data. The network access method used in
LAN 18 is conventionally known as token passing. A token is a special bit
pattern that constantly travels around the network. Every device in the
network must wait until it receives the token, before it can transmit its
message, reinserts the token in the network, which is then passed to the
next device in the network. If a device has no message to send, it allows
the token to pass to the net device in the network. In effect, possession
of the token is permission to transmit a message.
The transmission medium connecting devices in LAN 18 can be either a
broadband or a baseband coaxial cable. Baseband coaxial cable carries one
signal at a time, but the signal travels at a rapid speed-in the range of
ten million bit per second. Any of a number of conventional methods are
used to allow many devices to access LAN 18 concurrently.
The devices comprising LAN 18 include a plurality of single-board computers
each having a special function in serving the subscribers, as well as a
random access memory, a clock, and input/output facilities. The
single-board computers each include specialized application software and
are associated with an interface which connects it to LAN 18. In addition
to the single-board computers, LAN 18 further comprises a large-scale data
base 28 conventionally referred to as a "disc farm". Stored in the data
base's hard disk memory units is digital information representing video
presentations of goods or services. Generally, these video presentations
comprise television quality, still-frame images, or textual information,
or textual information overlaid on a still-frame image, or any combination
of the foregoing. These video presentations may be accompanied by an audio
message and are referred to hereafter as "video/audio presentations". Any
of these stored video/audio presentations can be viewed by a subscriber
upon request during any session on the system 10. Also stored in data base
28 is navigational information describing the pathways between
presentations, as well as information about subscribers. Typically, the
companies offering goods or services to subscribers develop a structure of
video/audio presentations representing an electronic store.
One example of the single-board computers coupled to LAN 18 are those
manufactured by Intel Corporation of Santa Clara, Calif. and are
designated as Model No. iSBC 36/100 or Model iSbc 186/100. The computers
are denoted according to their functional application in the LAN 18, and
are identified in FIG. 1 as the session server 20, navigation server 22,
subscriber information server 24, and cashier server 26. While the servers
20,22,24, and 26 are each identified by a single functional task, the
present invention anticipated that each server will have appropriate
software so that the server can switch functions depending on the demands
of system 10. During any subscriber session on system 10, one session
server 20 will be dedicated to serving a particular subscriber. The number
of session servers 20 at any LOC 11 will depend on the number of
subscribers serviced by the LOC 11. Accordingly, the number of session
servers 20 at a LOC 11 could be anywhere in the range of 100 to 2,000
units.
The output message from VNI 14 is transmitted through interface 16 to one
of the plurality of session servers 20. Interface 16 associates an
incoming subscriber call to an available session server 20. The session
server 20, like all the servers comprising the LAN 18 is itself connected
to LAN 18 by means of an interface. Though each server is shown in FIG. 1
as connected to an interface, in the physical construction of LAN 18 an
interface may be shared by a plurality of servers.
Session server 20 processes the message by translating or converting it
into some logical signal that the other servers understand, and then
passes the signal on to LAN 18 for further processing by the other
servers. In essence, the session server 20 interprets the digital signal
representing a key on the Touch-Tone telephone 12 and sends out a command
or commands to other servers on LAN 18. Included in these commands are the
subscriber's requests for selected presentations.
Navigation server 22 includes a dynamic RAM memory which can store at any
instance sufficient information to enable the subscriber to move about any
of the clients' presentation structures. The information stored in
navigation server 22 defines the pathways between the presentations in any
presentation structure. Since navigation server 22 incorporates a dynamic
RAM memory, it will only store navigation information that is useful at
any particular time in a subscriber session. Typically, the dynamic RAM
memory of navigation server 22 has approximately 10 megabytes of RAM
memory. Thus navigation server 22 is not capable of storing all of the
clients' presentation networks within its memory. This information is
stored in the hard disk memories of data base 28.
In operation of system 10, the subscriber designates the presentation or
presentations he desires to view by depressing keys on Touch-Tone
telephone 12. The digitized signals which represent the depressed
telephone keys are processed by session server 20 and are addressed to
navigation server 22. Navigation server 22 fetches from data base 28 the
navigational data needed at that time to move about a presentation network
in accordance with the subscriber's requests. Thus, for example, as the
subscriber requests information within a specific presentation structure,
the dynamic memory will only store navigational information about that
portion of the presentation network that could be requested by the
subscriber at that particular time in the subscriber session. A the
session proceeds and the subscriber moves about the presentation
structure, the navigation information within the dynamic memory will
change with the subscriber's movement in the structure. According to this
navigational data stored within its dynamic memory, and from its
interpretation of the digitized signals of session server 20, the
navigation server 22 determines which of the presentations stored in data
base 28 have been selected by the subscriber and transmits a signal
through LAN 18 for the data base 28 to transmit the requested
presentations to the subscriber.
Subscriber information server 24 stores information about system 10
subscribers. The information stored abut each subscriber includes the
subscriber's telephone number, the subscriber's personal identification
number, and it identifies a presentation player designated to receive the
subscriber's requested presentations. As will be explained in more detail
below, the presentation player receives, stores, and re-transmits to the
subscriber those presentations requested by the subscriber.
Typically, server 24 is active for only a portion of any subscriber
session. In the operation of the system 10, session server 20 queries
subscriber information server 24 for information concerning a subscriber.
Server 24 then fetches the requested information and sends it to session
server 20 which stores the information in its memory. Since session server
20 is active during the entire subscriber session there is no further need
to query server 24 for information during the remainder of the
subscriber's session.
Cashier server 26 processes all information concerning the subscriber's
purchases of merchandise or services. For example, cashier server 26
queries the subscriber as to the means by which he intends to pay for
purchases. If the subscriber selects a credit card as means for payment,
cashier server 26 accesses the subscriber's credit card identification
number from data base 28 and transmits an appropriate message to an
authorization service so that the purchase is charged to the subscriber's
credit card. Another function of cashier server 26 is to advise the
clients of purchases so that the goods are sent expeditiously to the
subscriber.
Purchase information can be transmitted on-line to the client or it can be
stored in cashier server 26 and "batched" to a client at a later time. For
example, all purchases made during a given period are stored by cashier
sever 26 in a storage data file, but at the send of the period they are
sent in batches to the various clients for further processing. Cashier
server 26 can also describe the means by which the purchased goods will be
delivered to the subscriber. That is, it will advise the client whether
the goods are to be shipped and by which means, or whether the subscriber
will pick up the goods at the clients' store.
A second LAN 30, also a ring topology, is connected to data base 28 for
sending the digital signals representing the video/audio presentations to
a CATV system. Transmission of a single video frame requires approximately
30 kilo-bytes to 50 kilo-bytes of information. Since a large number of
bytes of digital information is required to represent the video or image
portion of a presentation, second LAN 30 is needed since it accommodates a
larger quantity of digital information at a higher rate of speed than
first LAN 18. To meet this requirement, the transmission medium of second
LAN 30 is a broadband medium and preferably a fiber optic cable comprising
several optical fibers having a broader bandwidth than first LAN 18 which
transmits sever hundred thousand bits of information per second.
A channel server 32 receives subscriber control information from first LAN
18 and information representative of selected video presentations from
second LAN 32 for transmission to a CATV head end 38. Interface 34 and
interface 36 respectively couple channel server 32 to first LAN 18 and
second LAN 30. Channel server 32 comprises a microprocessor, a RAM memory
of several megabytes, a forward-error correction encoder, and a modulator.
The video, audio and control information received by channel server 32 is
converted into a high-speed digital stream and modulated so that it is
suitable for transmission by a cable television network. Channel server 32
also schedules the order in which the information is sent to the cable
television network, and performs forward-error correction coding to assume
reliability in transmission by the cable television network.
Typically, a LOC 11 wills service approximately 5,000 to 10,000 subscribers
depending on its location. Each LOC 11 is capable of communicating with
other LOC's by means of a gateway 40 which in turn communicates with a
higher-speed transmission medium, such as a broadband terrestrial or a
communication satellite. Gateway 40 comprises a microcomputer having a
memory of at least several megabytes, and is coupled to first LAN 18 and
second LAN 30 by interface 42 and interface 44, respectively. In
communicating with other LOC's , LOC 11 can request information, such as a
video/audio presentation not found in its data base 28, and can in turn
respond to the requests of other LOC's .
In a conventional cable television network incorporating a CATV head end
38, trunk cables 46 emerge from the head end 38 as the primary signal
path. Along the trunk cables 46 are a plurality of nodes 48. At each node
48 a bridger amplifier 49 (shown in FIGS. 2,3, and 4) is generally located
to amplify the video/audio presentations and to convey them along a
secondary cable 50 to the subscriber's home 52. At each node 48, and
according to the present invention, a presentation player 54 is located
which has as an output at least one secondary cable 50. Eight potential
secondary cables 50 are shown in FIG. 2 as being connected to presentation
player 54, while only one of the secondary cables 50 is shown in actual
use. Along each secondary cable 50 a drop connection 56 to a drop cable 58
extends into the subscriber's home 52 for connection to a television set
60. Each drop cable 58 is typically a coaxial cable.
According to the present invention, the presentation player 54 is a
cable-television-outside-plant device about the size of a conventional
CATV bridging amplifier and generally has the same power and mounting
requirements as a bridging amplifier. Broadly defined, the presentation
player is a frequency-agile broadband receiver with a high-speed data
demodulator tuned by a narrow-band fixed frequency control channel. The
purpose of presentation player 54 is to receive from the CATV head end 38
a stream of digital packets representing the video/audio presentations to
convert these digital packets into video/audio presentations, and to
transmit particular video/audio presentations, on pre-assigned output
channels to requesting subscribers. Each presentation player 54 processes
only those digital packets representative of video/audio presentations
requested by subscribers assigned to that presentation player 54. That is,
the digital packets representing the video/audio presentations requested
by a subscriber are addressed to the specific presentation player 54
assigned the task of processing the video/audio presentation for the
subscriber.
Referring to FIG. 2, the presentation player 54 incorporates at least one
and as many as eight subscriber servers 62. The subscriber server 62 may
be available to only a single subscriber and installed in a home as
subscriber apparatus, but typically will be shared among a small group of
subscribers according to usage criteria. Any individual subscriber among a
predefined group may access a subscriber server 62 by telephoning the LOC
11 service number and logging on. When a subscriber has captured the use
of a subscriber server 62, no other subscriber in the same group may use
the subscriber server 62 until this first subscriber has finished. The
number of subscribers, and of simultaneous users, for whom a single
presentation player 54 has been installed depends upon (1) the number of
subscriber servers 62 present in the presentation player 54, (2) the
assumptions of average usage by the subscribers assigned to each
subscriber server 62, and (3) the number of subscriber-selectable output
channels available to the LOC 11 for transmitting the visual/audio
presentations within the cable television network.
The presentation player shown in FIG. 2 comprises eight subscriber servers
62; however, it is anticipated by the present invention that there may or
may not be more than one output channel frequency accessible by two or
more subscriber servers. Typically, presentation player 54 will be
installed near a bridging amplifier 49 and will serve between one and
eight simultaneous users serviced by one to eight secondary cables 50. The
specific number of secondary cables (or feeders) 50 distributed from a
presentation player 54 is determined by design criteria related to (1) the
number of homes served by the CATV feeder cable in question (2) the local
CATV-system channel allocation, and (3) the local installation and utility
make-ready considerations.
In addition to the subscriber servers 62, each presentation player 54
further includes a subscriber server controller 64 and a presentation
player converter 66. The choice of configuration of any presentation
player 54 will depend upon the service needs of the area in which the
presentation player 54 is installed.
Presentation player converter 66 is tuned to a fixed-frequency, narrow-
band control channel in order to tune itself to a broadband channel for
receiving the digital packets representative of the vide/audio
presentations. In other words, converter 66 receives tuning information on
the narrow-band control channel and in response to this information tunes
itself to the designated broadband channel carrying the stream of digital
packets being broadcast by LOC 11. This self-tuning arrangement causes the
presentation player converter 66 to select the correct channel, demodulate
the signal to form a digital stream appropriate for local processing,
perform forward error correction, and determine whether packetized
information within th digital stream being monitored is intended for a
particular subscriber server 62 housed within the presentation player 54.
In essence, the presentation player converter 66 is a frequency-agile
broadband receiver with a high-speed data receiver tuned by a narrow-band
fixed frequency control channel.
The output signal from presentation player converter 66 is transmitted to
subscriber server controller 64 as shown in FIG. 2. Subscriber server
controller 64 is a dispatching device which routes signals from the
presentation player converter 66 to the appropriate subscriber server 62.
That is to say, subscriber server controller 64 determines the specific
subscriber server 62 designated to receive the packetized information.
This packetized information includes video and audio packets
representative of the video-audio presentation, as well as a presentation
script. The presentation script determines when and for what period of
time the subscriber server 62 will transmit video and audio frames
representative of a particular video/audio presentation. The operation of
subscriber server 62 includes the completion of a digital to analog
conversion of the video/audio presentation, insertion of graphic
information which is constructed from ASCII characters, the mixing in of
background audio music and the transmission of the video/audio
presentations on the assigned output channels incompatible NTSC format for
viewing by the requesting subscriber.
The function of presentation player converter 66 is to locate and tune to
that frequency band within the CATV spectrum where the digital information
stream is located, and to transformand monitor this information for
processing and handling details as required to deliver video/audio
presentations to requesting subscribers. This function of presentation
player converter 66 is more apparent from the following description of its
components.
Referring to FIG. 3, presentation player converter 66 includes
fixed-frequency receiver 68 which is permanently tuned to a predetermined
narrow-band control channel within the CATV spectrum. This narrow-band
control channel, for example 10kHz or less in bandwidth contains the
information required by converter 66 to control presentation player 54.
Fixed control channel receiver 68 transmits digitally encoded information
to a demodulator 70 implemented in VLSI at a rate of approximately 9600
bits per second. At this rate, as many as one hundred million destination
addresses can be controlled along with error correction overhead,
presentation format variants and a set of diagnostic commands. After the
demodulator 70 performs a forward error correction, it passes the signal
to a receiver controller 72 which stores handling and processing commands
including product presentation script instructions, video/audio packet
designations, diagnostic reporting schedules, and local storage of
subscriber information screens.
The frequency of the designated, high-speed input channel is transmitted by
receiver controller 72 to a frequency-agile broadband receiver 74.
Receiver 74 tunes to the channel designated by receiver controller 72. The
designated channel signal is sent by receiver 74 to a demodulator 76.
Demodulator 76 converts the analog signal into a digital bit stream,
performs forward correction and then sends the digital packets thereby
received to receiver controller 72. At receiver controller 72 the digital
packets intended for the presentation player 54 are selected and
transmitted to subscriber server controller 64.
Subscriber server controller 64 sends the digital packets of information to
one of the subscriber servers 62 which resides in the presentation player
54. In accordance with addressing information included within the digital
packet. Each subscriber sever 62 housed within a presentation player 54 is
responsible for processing the digital packets of information designated
for subscribers assigned to that particular presentation player.
Referring to FIG. 4, the packets of information transmitted from subscriber
server controller 64, are received by a small CPU 78 in the subscriber
server 62 and are stored in an RAM pool 80. CPU 78 determines which of the
information packets is a script packet and then uses the script packet to
determine how the video and audio packets are to be combined with graphic
information in real time for viewing by the subscriber. The script packets
also define fidelity and duration of background and overlay audio, as well
as screen location and duration of video images with accompanying visual
text. Moreover, the script packets may define an automated series of
audio/video sequences in fulfilling a specific request from a subscriber.
In case of error detection during preparation of a product presentation
sequence, the subscriber error controller 64 will substitute a substitute
message from local RAM to communicate information or instructions to the
requesting user.
From CPU 78, the script packets are transmitted to a video expander 82 or
an audio expander 84 depending on whether they contain visual or audio
information. A video expander 82 includes graphic overlay capabilities, as
well as functions for reversing the process as defined by a video
compression algorithm. Audio expander 84 decompresses the audio packets
and converts them into real time. The video and audio packets are also
processed by video processor 86 and audio processor 88, which includes
conversion of the digital formatted audio and video into an analog format.
After the video and audio information have been queued and expanded, they
are used to modulate a subscriber-selectable CATV channel by means of an
output modulator 90, a frequency-agile transmitter, which transmits to the
requesting subscriber the assembled presentation in NTSC format on the
frequency assigned by the CPU 78 as directed by the LOC 11. Accordingly,
it is through the presentation player 54 that the requested video/audio
presentations are transmitted on pre-assigned output channels to the
requesting subscribers.
Although the illustrative embodiment of the present invention has been
described in detail with reference to the accompanying drawings, it is to
be understood that the invention is not limited to this precise embodiment
and that various changes or modifications may be effected therein by one
skilled in the art without departing from the scope or spirit of the
invention.
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