Note: Descriptions are shown in the official language in which they were submitted.
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BP File No. 7178-009
T' e: A Video and Audio Emergency or Warning System
for a Cable Television Network
FIELD OF THE INVENTION
This invention relates to an emergency broadcast
system which is suitable for cable television network use. More
particularly, the present invention relates to a system which allows
the video and/or audio programming to be automatically
1 0 interrupted for emergency announcements.
BACKGROUND OF THE INVENTION
There are known emergency warning systems for use
by television broadcasters. These allow for manual intervention, by
the broadcaster, of the existing programming in response to
receiving an emergency or warning notification from a
government authority or appropriate message originator.
Cable television has become the primary delivery
system to the home in modern television infrastructures. The cable
2 0 distributor usually supplies both distant and local television signals
to the home. Emergencies, however, are usually of a local nature.
Transmission of video and audio signals to local cable
television stations for immediate use, rebroadcast, or recordation
for later broadcast is well-known. The broadcast of emergency
2 5 warnings over television, for example weather storms, is also
known. The existing television networks provide a convenient
vehicle for reaching the public in times of emergency.
In known systems, the scheduled programming is
typically manually interrupted by the local broadcaster using a
3 0 combined audio and visual warning announcing the emergency
information. The broadcaster receives notification of an emergency
or warning from an emergency or national authority (e.g. tornado
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watch from the National Weather Service). It will be appreciated
this emergency warning procedure can be a slow process.
While this approach may be acceptable for some
emergency warning systems, it falls short of providing an effective
and flexible emergency announcement which accommodates both
the needs of the public and the commercial realities of operating a
television network. For example, certain emergency situations may
entail more information than can be displayed across a single line,
and therefore the emergency announcement system should have
1 0 better capability of providing information for the viewer in a
minimally disruptive way. In other emergency situations, for
example, a weather storm warning or other low priority event, the
emergency is not impending and therefore it is not necessary to
immediately warn the public. If the emergency announcement
1 5 system pre-empts a commercial spot, then the television station
will lose revenue in a situation when immediate notification of
the public is not necessary. Furthermore, the manual nature of the
emergency notification can result in a slow speed of response.
Some work has been done on a device that can be inserted between
2 0 the cable company's signal receiving equipment and the cable
channel modulators. Such devices are based on videotext and
therefore it can be very expensive to install this equipment.
Given the importance, but disruptive nature, of an
emergency warning system, there is a need for an emergency
2 5 announcement system which can be integrated, in a cost effective
manner, with a television network to provide priority warning
announcements to the public on a timely basis, while at the same
time minimizing disruptions to the commercial operations of the
television network.
SUMMARY OF THE INVENTION
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The present invention provides a system for weather
and emergency organizations to alert cable television viewers of
impending dangers, e.g. weather warnings, chemical spills. The
system can include the capability for placing text messages on
selected channels; for an override video to be switched onto desired
channels; and for an override audio to be switched onto desired
channels. The system can include the capability to provide the
emergency notifications with varying degrees of interruption to the
scheduled programming.
In one aspect, the present provides a system for
alerting viewers on a cable television network having a plurality of
cable channels available to the viewers, said system comprising: (a)
receiving means for receiving an emergency or warning
information message; (b) processing means for decoding said
1 5 information message, said processing means including insertion
means for inserting an emergency or warning information field on
one or more of said cable channels; (c) channel scheduling means
coupled to said processing means, said channel scheduling means
including means for providing an emergency or warning message
2 0 blocking signal to said processing means, and said processing
means including routing means responsive to said message
blocking signal for blocking said insertion of said alerting
information field.
Preferably, said insertion means further includes
2 5 means for inserting an emergency or warning information page on
another selected cable channel, said emergency or warning
information page containing more emergency or warning
information than does said emergency or warning information
field; and wherein said emergency or warning information field
3 0 includes a direction to direct the viewers to said other selected cable
channel for viewing said emergency or warning information page,
said emergency or warning information page providing a detailed
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message on said selected cable channel with minimal disruption to
said other cable channels.
In another aspect, the present invention provides a
system for receiving emergency or warning information messages
from a remote agency and inserting emergency or warning
information on selected channels of a cable television network in
order to provide a warning system for viewers of the cable
television network having one or more cable channels, said system
comprising: (a) communication interface means for receiving an
emergency or warning information message from the remote
agency; (b) processing means for decoding and responding to the
information message; (c) channel scheduling means coupled to said
processing means, said channel scheduling means having means
for providing to said processing means an emergency or warning
1 5 message blocking signal for each of the cable channels in the cable
television network; (d) said processing means including routing
means responsive to said message blocking signal for blocking
routing of said emergency or warning information message; and (e)
said processing means further including means for producing an
2 0 emergency or warning information field and means for inserting
said emergency or warning information field on one or more
signals of the cable channels for notifying the viewers of the cable
television network.
In yet another aspect, the present invention provides a
2 5 method for alerting the viewers of a cable television network
having one or more cable channels available to the viewers, said
method comprising the steps of: (a) receiving an emergency or
warning information message from a central agency; (b) processing
said information message to determine one or more cable channel
3 0 destinations for said alerting information message; (c) using a
channel scheduling signal to determine if said one or more cable
channel destinations can be interrupted by said information
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message; and (d) routing said information message only to those
cable channel destinations which can be interrupted as determined
in step (c).
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention,
and to show more clearly how it may be carried into effect,
reference will now be made, by way of example, to the
accompanying drawings in which:
Figure 1 shows in block diagram form a system
according to the present invention in relation to a cable television
network and an emergency broadcast agency;
Figure 2 shows in diagrammatic form a typical cable
television network which is suited for use with the system of
1 5 Figure 1;
Figure 3 is a detailed block diagram of an alert unit for
the system shown in Figure 1;
Figures 4i and 4ii are a flow chart which shows the
emergency broadcast modes available for the system of Figure 1;
2 0 Figure 5 shows the format of the message packets used
by the system of Figure 2; and
Figure 6 is a flow chart which shows a commercial
blocking and day-parting feature for the system of Figure 1.
2 5 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference is first made to Figure 1 which shows in
block diagram form an overview of a video and audio alerting
system according to the present invention. The purpose of the
system 10 is to distribute emergency messages and warnings to
3 0 various regions which are serviced by a television or other form of
communication network.
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In the following explanation, the alerting system 10 is
integrated with a cable television network 11 as shown in Figure 2.
The cable network provides the link between the alerting system 10
and the final home viewer. The alerting system 10 is located at a
"cable head-end" 20 for each region which is to be serviced. As will
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be explained in detail below, the alerting system 10 according to the
present invention has the capability to place (in a number of
different ways) emergency messages on any or all the channels
carried by the cable television network 11.
As shown in Figure 2, the video and audio alerting
system 10 is configured to receive emergency alerting information
from one or more message originators 12 via a satellite
communication link 14. The message originators 12 are typically a
government emergency or other official warning agency. The
~ o emergency information is first received and processed by a control
center 16. The control center 16 verifies and then processes the
information and oversees the administration and control of the
systems 10 located at the cable head-ends 12. As shown in Figure 2,
the message originators 12 can be coupled to the control center 16
~ 5 using a variety of communication conduits, for example, the Data
Pac network, the AMOS link, or a conventional telephone line.
The emergency warning agency 12 can be any agency
which provides emergency warnings, e.g. a government weather
agency or the Department of Defence. The role of the agency 12 in
2 o the context of the present invention is to provide emergency
messages for distribution to the regions of the state, province or
country which are serviced by the alerting systems 10. The
emergency warnings and messages from the agency 12 can be
designated for a particular region or at a certain priority, and as will
2 5 be explained belorir, the system 10 according to the present
invention has the capability to provide various levels of messaging
and distribution.
The control center 16 is the pre-processor of the '
emergency information and the master over the remote alerting
3 o systems 10. The control center 16 uses the satellite communication
14 to transmit .control data and emergency information to the .
remote alerting systems 10. The control center 16 includes a central
~~ ~~~23
computer 18 which is used to validate emergency information
from government agency 12 and ensure that it meets the required
standards and formats. The central computer 18 also controls
addressing of the remote alerting systems 16. Once the emergency
information from the agency 12 has been validated, the central
computer 18 formats and transmits the information according to
the protocol utilized by the alerting system 10.
The cable head~end 20 includes a known system for
providing the cable television programming to the cable
o subscribers, which primarily involves retransmitting programs
broadcast by the television networks. For the purposes of this
discussion, the cable television programming system is represented
by block 26. The alerting system 10 located at the "cable head-end"
20 comprises a controller/demodulator 22, one to three alert units
t 5 24 and a local overnde video and audio signals source 25. The cable
television signals video and audio) from a number of sources 21, '
e.g. satellite receiver, microwave receiver or fiber cable receiver as
shown in Figure 1, are also coupled to and routed through the alert
unit 24. The controller/demodulator 22 receives the emergency
2 o information and converts it to the required format in order to
display the information as static or scrolling text on any or all of the
channels with a minimum of visual degradation to the original
cable signal. The system 10 also has the capability of substituting the
override video and/audio signals 25 for the original cable signal as
2 5 will be explained below. In the absence of any emergency messages
or conditions, the alert unit 24 does not alter the video and audio
signals received from the cable television sources 21.
The controller/demodulator 22 is also coupled to a
programming/commercial scheduling manager 26. The scheduling
2106~w3
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commercial time-slots for the programming which is being
broadcast by the cable television station or cable head-end 20. The
manager 26 can use the channel profile data base 27 to support the
following features: (1) day parting; (2) commercial spot schedules;
(3) priority; (4) postal codes; (5) authorization check; and (6) traffic
logging. The channel profile database 27 is preferably organized on
a channel by channel basis. The channel profile database 27 can be
administered through a data channel from the controller 22 or
locally through the computer 29.
1 o The day-parting and commercial spot schedules are
used by the manager 26 to "lock-out"emergency warnings or
announcements based on the requirements of the cable television
station. The day-parting and commercial play schedules prescribe
periods when a channel is not available to the warning system. As
shown in Figure 1, this decision is made upstream of the unit 24 in
order to block the input of the emergency video and audio into the
unit 24 in order to prevent pre-emption by the emergency
announcement. The blocking can be affected through the manager
26 interrupting the emergency video and audio feed to the unit
2 o through a switch for example. For example, the scheduling
manager 26 can use the commeraal schedule to block low priority
emergency warnings or announcements during the airing of a
commercial to avoid pre-empting of the commercial and the
consequent loss of advertising revenue. Similarly, the scheduling
2 5 manager 26 can use the "day-parting" schedule to block emergency
warnings or announcements for a specified period, for example,
. during normal business hours when the cable station's newsroom
is working.
' The priority and associated response data allows
3 o individual broadcasters to define their level of participation within
the warning system 10. The priority and associated response data
can be entered through a local input terminal, for example, the
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controller 29. For example, during periods when the news rooms
are in operation, the broadcaster may wish to have priority for their
own response. Similarly, a low priority emergency notification
cannot pre-empt a commercial spot having a higher priority.
5 Furthermore, distant signal originators (e.g. signal
receivers 21 in Figure 1) while not interested generally in providing
a local response, may still wish to protect their commercial
schedules. It will be appreciated by those skilled in the art that the
channel profile database 27 can also be used by distant broadcasters
10 to provide a configurable participation level in the emergency
alerting system 10 as specified by the schedules in the channel
profile database 27.
The postal code data in channel profile database 27 can
be used in conjunction with a postal code field imbedded in the
1 5 command structure to validate traffic to alerting unit 24 on a
channel by channel basis. See command structure below.
The authorization data in the channel profile database
27 is used to confirm the validity of the user in a local application,
for example, configuring the database 27 using a local terminal 29.
2 o The authorization data is typically downloaded from the controller
16 via the satellite link 14.
The traffic log feature can also be implemented in the
channel profile database 27 to provide a 30-day traffic log, for
example. The traffic log can be used to generate an activity report
2 5 which details the pre-emption of the cable station on a channel by
channel basis.
Referring back to Figure 1, the controller 22 is designed
in known manner to receive a base-band signal with a data
subcarrier via a satellite dish 15 (and receiver). The controller 22
3 0 decodes the received data and determines if the data is applicable to
the cable head-end 20 and outputs it on a data line 31 (shown as a
broken line) which is coupled to an interface board 30 in the unit
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24. As will also be described in detail below, the alert unit 24 then
determines to which channels) the data will be applied. It will be
appreciated by those skilled in the art that this arrangement
provides considerable flexibility for displaying emergency messages
and information. The alert unit 24 receives commands and data
messages (or packets) from the controller 22. The alert unit 24
interprets the commands and data messages to display the
emergency messages on the desired cable channels in the required
format as will be discussed in more detail below.
1 0 If the programming/commercial scheduling manager
26 is being implemented with the system 10, then the data line 31 is
coupled to the controller 29, and the computer 29 has an output
data line 33 which is coupled to the input on the alerting unit 24.
The controller 29 runs a computer program which "screens" the
1 5 incoming emergency notifications according to the content of the
channel profile database 27 as will be described below. For example,
in the commercial pre-empting block feature, the manager 26 will
block the command/data messages from reaching the alert unit 24
(on data line 33) until the commercial has played.
2 0 Reference is next made to Figure 3 which shows the
alert unit 24 in detail. In the preferred embodiment, the alert unit
24 comprises nine channel boards 28, and the interface board 30.
Each channel board 28 is designed to process four cable channels,
giving the unit 24 a thirty-six channel capacity. In addition, up to
2 5 three units 24 can be daisy-chained with controller 22 for a total
capacity of 108 cable channels, which is sufficient capacity for a
typical cable head-end. The following describes the circuitry for the
first cable channel (indicated generally by reference 29) on channel
board 28. The circuitry for remaining 35 channels (which can be
3 0 configured in a unit 24) is virtually identical to the circuitry shown
in Figure 3 for the first cable channel 29.
-11~~~6~~~
The alert unit 24 is housed in a rack-mount chassis or
cabinet (not shown). The channel boards 28 and interface board 30
are coupled to a main backplane 32. The alert unit 24 also includes a
power supply (not shown). The main backplane 32 has slots for
each of the channel boards 28 and the interface board 30. The
backplane 32 is mounted across the back of the chassis (not shown)
and includes connectors (e.g. BNC type and terminal strips) for
coupling the alert unit 24 to the controller 22 and the cable
television signal sources 21.
t o Each channel card slot in the backplane 32 includes a
hardwired slot numbex 34. The slot number 34 comprises four
hardwired pins that define the number (i.e. 1 through 9) of the
channel board 28 which is mounted in the slot on the backplane 32.
The backplane 32 also includes a unit identifier 36 which identifies
t 5 the alert unit 24. Since up to three units 24 can be daisy-chained, the
unit identifier 36 comprises two lines which can be set by jumpers
or a DIP switch (not shown) on the backplane 32. The channel card
28 identifies and decodes messages which have a tag corresponding
to the unit identifier 36 and slot (or channel board) number 34. This
2 o arrangement allows the controller 22 to access channel boards 28
both on a board level (i.e. slot number 34) and on a chassis level
(i.e. unit identifier 36).
Referring to Figure 3, the backplane has a video signal
input 38 for each cable channel (comprising a BNC connector) and
2 5 an audio signal input 40 for each cable channel. The video signal
input 38 is coupled to the channel board 28 and in an emergency
situation, the video signal for that channel will be processed by the
channel board 28 according to the emergency notification data and
command messages which are received from the controller 22 as
3 o will be discussed below.
If a channel board 28 has failed or is not plugged into
the backplane 32, the alert unit 24 will provide fail-safe operation
and not interrupt the cable programming system 26. The backplane
. ,
32 includes a video signal by-pass relay 42 and an audio signal
by-
pass relay 44. The by-pass relays 40,42 have normally closed
contacts
which are controlled by the channel board 28. If the channel
board
28 is defective or unplugged, then these contacts will be closed
and
the video signal input 38 and audio signal input 40 will be
routed
to the channel video signal output 39 and channel audio signal
output 41. lNhen a channel board 28 is unplugged, the associated
by-pass relays (42 and 44) will eonnect the video signal input
38 and
1 o the audio signal input 40 to the respective outputs 39 and 41
to
provide uninterrupted cable programming. When the channel
board 28 is replaced, the associate by-pass relays (42 and 44)
will
remain closed until the controller 22 directs the channel board
28 to
take other action. As shown in Figure 3, notwithstanding the
by-
~ 5 pass relay 42, the video signal input 38 is always available
to the
channel board 28, via lead 45. This allows the channel board
28 to
have uninterrupted video timing information which minimizes
the time required for synchronization when processing and
executing command messages.
2 o Referring still to Figure 3, the backplane 32 also
includes a replacement video signal feed 46, a replacement audio
signal feed 48, an internal bidirecdonal control/data bus 52,
a power '
and ground feed (not shown), a reset line 54, and a hardware
failure
line 56. The replacement video signal feed 46 is coupled to
a
2 5 overnde video signal input 60 and override video signal source
61
(shown as block 25 in Figure 1), which supplies each of the
channel
boards 28 with a video signal which can be substituted for the
original cable video signal input 38. It will be appreciated
by those
skilled ~ in the art that the video signal feed 46 must be properly
3 o terminated on the backplane 32, and unterminated tracks (not
shown) must be laid out to avoid reflections. The replacement
audio feed 50 is coupled to an override audio signal input 64
(and
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override audio signal source 65 - shown as block 25 in Figure 1).
The replacement audio feed 50 is connected to the respective by-
pass relays 44. The audio by-pass relays 44 are controlled by the
respective channel board 28. Although the channel audio input 40
(override audio signal input 64 and replacement audio signal feed
48) are shown as single lines, these signal lines are implemented as
a differential signal pair. The bidirectional control/data bus 52
provides the communication link between the channel boards 28
and the interface board 30, as will be explained in more detail
o below. The interface board 30 drives the reset line 54, which ..
pravides a hardware reset to the channel boards 28. The interface
board 30 also monitors the failure line 56 to detect any defective
channel boards 28.
The alert unit 24 (chassis) also includes a power supply
~ 5 (not shown). A switching type power supply is preferred and the
selected supply must be stable over a wide range of current
consumption, as the number of installed channel boards 28 can
vary from unit to unit.
Referring still to Figure 3, the primary functions of the
2 o interface board 30 are to buffer the replacement video and audio
signals and drive the replacement video and audio signal feeds 46
and 48 on the backplane 32, and to provide an interface between the
controller/demodulator 22 and the channel boards 28, via the data
line 31 or 33.
2 5 The interface board 30 includes a high impedance
video buffer 58 which couples a replacement video signal input 60
to the replacement video signal feed 46 on the backplane 32. The
video signal feed 46 appears as a transmission line terminated by an
impedance of 75 ohms at each end. Therefore, the video buffer 60
3 0 must be capable of driving a 37.5 ohm resistive load. The audio
signal feed 48 is handled differently. Because it is undesirable to
bring audio onto the channel boards 28 and no active components
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are to be installed directly on the backplane 32, the board 30
includes a high power driver 62 which is coupled to a replacement
audio signal input 64 and to each of the by-pass relays 44 (through a
resistor network (not shown)). '
As shown in Figure 3, the interface board 30 also
includes an interface microcontroller (and firmware) 66. The
interface microcontroller 66 can be implemented using the Intel
MCS-52 family of microcontrollers which can include on-chip read-
only program memory (ROM) or an external EPROM, random
1 o access memory (RAM), and other on-chip resources such as
input/output ports, and timers/counters. The microcontroller 66
can include the capability to run software programs which 'are
downloaded from the central computer 18. This can be
implemented by including a "bootstrap" routine in the read-only
~ 5 memory and random access memory in the program space of the
microcontroller, as will be understood by one skilled in the art.
For
example, when the interface microcontroller 66 is 'first powered-on
it will execute the bootstrap routine until a update or downloaded
program is received from the central computer 18. In this way, the
2 o software for each remote alert unit 24 can be upgraded or
administered from a central location.
The primary function of the interface microcontroller
66 involves receiving command/data packets on data input line 33
(or 31) from the controller and demodulator 22 and translating
2 5 these packets into the binary protocol used by the channels boards
28 on the control/data bus 52. The interface microcontroller 66 uses
a serial communication link 68 (e.g. RS-232 type) to receive and
transmit command/data packets from and to the
controller/demodulator 22.
3 o For downstream communication, the interface
microcontroller 66 converts the packets received from the
controller/demodulator 22 into the known HDLC/SDLC protocol
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-15-
for communication on the internal bus 52. In the upstream
direction, the interface microcontroller 66 converts the packets
received from the channel boards 28 into the RS-232 format
required by the controller/demodulator 22. The communication
link 68 includes hardware flow control, i.e. a request to send line
(RTS) and a clear to send line (CTS) to administer communication.
Alternatively, the flow control can be implemented in the
firmware of the microcontroller 66. The commands received by the
interface controller 66 are listed in the attached Appendix.
The interface microcontroller 66 also monitors the
hardware fault line 56, which indicates if a channel board 28 has
failed. If a channel board 28 has failed the interface microcontroller
66 will send a fault message (see Appendix) to the
controller/demodulator 22. In response to a failure, the interface
controller 66 can also affect a reset (via the hardware reset line 54
on the backplane 32) to the channel boards 28. The reset can be used
to restart the channel board microcontroller and firmware (see
below), and to put the channel board 28 into a known state, which
can be confirmed by a status inquiry command (see Appendix).
Reference is next made to the channel board 28 shown
in Figure 3. Each channel board 28 supports four cable channels
(video 38 and audio 40). The channel board 28 includes a
microcontroller 70, four character generator circuits or chips 72 (one
for each video channel 38), a video buffer 74 for the cable video
input signal 40, a video buffer 76 for the replacement video input
signal feed 46, and a video buffer 78 for the video output signal.
The character chip 72 is used by the alert unit 24 to generate the text
characters for emergency or warning messages which are to be
displayed on the cable video channels. (This will be explained in
more detail below.) The input of the character chip 72 is coupled to
a video switch 80 which is used to select the video input signal, i.e.
cable video 38 or replacement video 46, under the control of the
CA 02106223 1999-09-O1
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microcontroller 70.
The channel board 28 microcontroller 70 can also
comprise a monolithic integrated microcomputer which has on-
chip programmable read-only memory (PROM) or external
5 EPROM, and random access memory (RAM), a communication
port (which couples to the bi-directional bus 52). As for interface
microcontroller 66, the channel board microcontroller 70 includes
random access memory in the program space to allow downloading
of software via the serial communication link 68 and internal bus
1 0 52. The microcontroller 70 includes a bootstrap routine in PROM
and can also include the operating program which is executed until
a software download is detected or received.
The microcontroller 70 includes a software (firmware)
program which is stored in the read-only memory and random
1 5 access memory (which is mapped to the program space of the
microcontroller 70). The primary functions of the firmware is to
receive and execute the control/data messages which are
transmitted by the interface microcontroller 66 on the control/data
bus 52. The firmware includes a command interpreter routine
2 0 which receives and executes the command/data packets from the
bus 52, which is within the understanding of one skilled in
microprocessor programming. For the purposes of this discussion,
the command/data packets transmitted to the microcontrollers 70
on the channel boards 28 will have the same format as those listed
2 5 in the Appendix. The firmware also includes routines or drivers
for communicating directly with the four character generator chips
72 on each channel board 28. The firmware uses the random access
memory as a buffer for the text which is downloaded by the central
computer 18 via the controller 22 and interface board 30.
3 0 The character generator chip 72 is the BU2801S On
Screen Display Integrated Circuit which is manufactured by the
Rohm Corporation. The microcontroller 70 uses a serial link to
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load character and control data into the on-chip RAM on the
character generator chip 72. The channel board 28 can include an
additional bypass switch 82 which allows the selected input video
(i.e. cable 38 or replacement video feed 46) to bypass the character
5 generator 72. This function can also be implemented in the
character generator chip itself.
The microcontroller 70 also has an input port 84
which is coupled to a vertical synchronization pulse circuit 86. The
input port 84 is configured as an interrupt. The vertical
10 synchronization circuit 86 provides the microcontroller (and
firmware) 70 with sync pulses for the four video channels. The sync
pulses are required by the firmware to properly manage the display
tasks. It is important that the microcontroller 70 insure
synchronization with each video channel so that the emergency
1 5 message can be displayed without too much disruption to the
underlying video signal. The microcontroller 70 also has an input
port 88 for reading the unit identifier 36 and the slot address 34. The
firmware uses the address information to identify messages on the
bus 52 which are to be decoded and executed.
2 0 Referring still to Figure 3, the microcontroller 70 has a
reset input 90 which is coupled to the hardware reset line 54 on the
backplane 32. Each channel board 32 includes a failure indicator 92,
which can be a red light-emitting diode (LED). The indicator 92 can
be coupled to microcontroller 70 to signify error conditions arising
2 5 under the inspection of the microcontroller 70. The signal to the
indicator 92 can be logically "ANDed" with the reset signal 54 to
reset only the channel board 28 which is reporting a failure.
In operation, the microcontroller 70 receives
command and data packets from the bi-directional bus 52. The
3 0 microcontroller 70 (firmware) selects or deselects the packets
(defined in the Appendix) according to the tag identifier which
-18-
corresponds to the unit and slot addresses 36,34 or which
corresponds to a dynamic identifier i.e. stored in memory and
referenced to the tag identifer. The microcontroller 70 (and
firmware) has the capability to send acknowledgement messages
and status messages in response to an inquiry packet, for example.
However, the primary function of the microcontroller 70 (and
firmware) is to store and display text messages via the character
generators 72 on the channel cable video signals 38 for selected
cable channels.
On a firmware level, the microcontroller 70 processes
control/data commands received on the bus 52 and updates and
manages the video signals (and audio signals) according to the
command directions. For example, the central computer 18 can
instruct a static text display on cable channel 1 and a scrolling
horizontal text line on cable channel 3. Once the text has "scrolled"
for the selected time or interations, the channel returns to normal
video. In response to a power-on reset, the microcontroller 70
executes the firmware program from EPROM.
The operation of the alert unit 24 can be explained as
follows. Under normal conditions, the alert unit 24 is a passive
device which is transparent to cable video and audio signals 38,40
(Figure 3), i.e. the channel video signal 38 and channel audio signal
40 are passed through the channel board 28 undisturbed, (or
through the closed by-pass relays 42,44 if the channel board 28 is
unplugged from the backplane 32). Under active conditions, e.g.
emergency notification, the alert unit 24 implements certain
operations in response to commands and data which are received
from the control centre 16 via the satellite 14 and
controller/demodulator 22.
In the present embodiment, the alert unit 24 supports
the following modes of operation: (1) superimpose text as a crawl
message on the cable video channel; (2) superimpose text as a static
CA 02106223 2000-O1-14
-19-
text window on the cable video channel; (3) replace the cable video
signal 38 with the override video signal 60; (4) superimpose text as
a crawl message onto the override video signal 60; (5) superimpose
text as a full text page onto the override video signal 60; and (6)
replace both channels of the cable audio signal 40 with the override
audio signal 64.
These modes of operation provide the alert unit 24
with the capability to display emergency messages with varying
degrees of disruption to the cable television viewer. The least
1 0 disruptive mode of operation is (1) which involves displaying a
crawl text message, and the most disruptive is (5) which replaces
the cable video with the override video and superimposes a full
text page. The modes of operation are implemented by the
firmware (resident in the program memory of each channel board
1 5 microcontroller 70) in response to a sequence of control and data
commands (Appendix) which are received from the controller
/demodulator 22 via the interface controller 66.
Reference is next made to Figures 4i and 4ii which
show in flow chart form the modes in which the alert unit 24 can
2 0 operate. The alert unit 24 operates under the control of the central
computer 18 in response to commands and data which are
transmitted to the controller/demodulator 22 as shown at block
300. The controller/demodulator 22 demodulates and decodes the
commands and data (received from the control centre 16 via the
2 5 satellite 14) and transmits the command and data packets in a serial
stream to the interface controller 66. In the present embodiment,
the interface controller 66 translates the command and data packets
from RS-232 format into the HDLC/SDLC binary protocol for
transmission on the bi-directional bus 52.
30 The communications protocol (Appendix)
implements a "tag" concept which allows: (1) command and data
packets to be broadcast to all channels in the alert unit 24; (2)
210~~23
- 20
commands and data packets to be direeted to a group of one or
more channels; and (3) a command or data packet to be sent to a
channel based on its physical location (i.e. unit number 36 and
board slot 34 and channel number 1 to 4). The tag is contained in
a
tag byte in each command and data packet. To broadcast a
command or data packet, the tag byte has a value of zero, which is
accepted and executed for all channels. To configure a selected
group of channels, the protocol has a "Tag Setup" command
(Appendix). The "Tag Setup" command assigns any group of
t o channels with a logical or dynamic identifier. The channel can
then
be accessed according to its logical identifier, physical tag or by
a
broadcast. In the present embodiment, a channel will only respond
to one dynamic tag value at a time. A tag assigned to a channel will
overwrite the previous tag assigned to that channel. The format of
~ 5 a command or data packet utilized in the present invention is
shown in Figure 5. The "tag" for the packet is contained in the
second byte.
The interface controller 66 puts the message packet on
the bus 52 and the packet is accepted by one (or more) channel
2 o microcontroller 70 based on the value in the tag byte of the packet
(Figure 5). Following this procedure, the central computer 16 uses
the control command via the controller/demodulator 22
(Appendix) to control the type and content of the emergency
announcement. If it is desired to substitute override audio (block
2 5 302), then the central computer 16 will transmit a control message
which specifies that the bypass relays 42,44 (Figure 3) be switched
to
, substitute the override audio and/or video. In response, the
channel microcontroller 70 will activate the bypass relays 42,44
(Figure 3) through output line 43 (Figure 3), as indicated at block
3 0 304. If the emergency announcement does not include an audible
notification, then block 304 is skipped, a command to substitute
overnde audio is not issued to the unit 24.
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-21-
An emergency announcement which includes a text
message (shown at block 306) can be presented to the viewer in a
number of ways. If the text message is to be superimposed on the
override video signal (at block 308), the central computer 16 will
transmit a control message which directs the selected channel
microcontroller 70 to substitute the override video signal 60 (Figure
3) by switching the video by-pass relay 44, indicated at block 310.
Once the override video decision has been made, the text display
format is deterined at block 312. The text message can be
displayed in one of four ways: (1) a static line; (2) a static page; (3) a
line of text crawling horizontally at a fixed rate; or (4) a text page
which scrolls vertically at a fixed rate. In the present embodiment,
the microcontroller 70 can store and display up to 240 lines of text.
In conjunction with the character generator 72, the microcontroller
can display the text as a line, a partial or full page of characters
displayed statically at any one of 10 line positions, or as up to 240
lines of contiguous text scrolling vertically. The text can be
downloaded by the central computer 18. In the present
embodiment, both the crawl and scroll rates have been fixed, and
approximately 12 seconds is required to traverse the screen.
If the text is to be displayed in the page format, the
central computer 18 transmits a control packet with the fourth byte
set to display the text as either a static page or a scrolling page (see
format for control packet in Appendix), at block 314. The number of
times a text page is to be scrolled can also be specified in the control
packet (bytes 5 and 6). Once the central computer 18 has specified
the text page format (and interations), the channel microcontroller
70 will execute the text page display as indicated by blocks 316 and
318 in Figures 3. At the completion of the text page display, the
selected channel can revert to normal programming until the alert
unit 24 receives additional instructions form the central computer
16 (block 320).
CA 02106223 1999-09-O1
-22-
If the central computer 18 instructs a text line display,
then the microcontroller 70 issues the appropriate instructions to
the character generator to provide a line display (block 322). If the
central computer 18 has requested a scrolling text line, then the
5 microcontroller 70 will also the appropriate control commands
according to the control packet contents, e.g. the number of scroll
loops.
The present invention includes a number of features
to provide maximum emergency notification with minimum
10 interruption to the scheduled programming and/or commercial
operation of a cable television station.
The first of these features allows the viewer, who is
watching any channel (or a selected channel), to be alerted by a brief
emergency announcement which directs the viewer to turn to a
1 5 selected channel for full details of the emergency warning or
announcement. For example, if there is a severe thunderstorm
tracking into the viewing area of the cable station 20, the central
computer 18 will download a single line text message which is to be
displayed on all or selected cable channels (i.e. as specified in the tag
2 0 byte of the command packet), other than one channel, which will
be used to display a more detailed message ("the detailed message
channel"). The detailed message channel can be, for example, a
weather channel. The microcontroller 70 will display the single
line message across the bottom of the television screen on all the
2 5 channels and the message will direct the viewer to turn to the
detail message channel for more detail. If the message is short it can
be displayed as a single static line of text, on channels other than
the detailed message channel. If the message is several lines, but
still relatively short, it can be displayed either as several lines or as
3 0 one line using the horizontal crawl feature, on channels other than
the detailed message channel. For the detailed message channel,
the microcontroller 70 will display the full text of the emergency
CA 02106223 2000-O1-14
-23-
warning which was downloaded by the central computer 18. The
degree of interruption can vary with the priority or seriousness of
the emergency.
Reference is made to Figures 4i and 4ii which depict
how this feature can be implemented by the system 10 as depicted
by blocks 328 and 330. The central computer 18 instructs the
channel microcontroller 70 to display a one line text message (static
or crawling) on all or a selected group of channels. The one line text
message, which is superimposed on the normal channel video
signal 38 but otherwise preferably does not affect the normal
channel video signal 38 or audio signal 40 on the cable channels in
question, prompts the viewer to turn to detailed message channel
for the emergency announcement and/or directions. On the
detailed message channel, the central computer 18 instructs the
1 5 channel microcontroller 70 to display a detailed message using the
text page format. In addition, the central computer 18 can instruct
the microcontroller 70 to display the override video signal 60 on
the detailed message channel in place of the normal video signal
38. The override video signal 60 can simply be a blue or other
2 0 background colour for the text message, which is supplied by a local
override video source 61 (Figure 3). The central computer 18 can
also instruct the channel microcontroller 70 to replace the channel
audio signal 40 with the override audio signal 64 on the detailed
message channel (or any other channel). The override audio signal
2 5 64 is supplied by a local override audio source 65 (Figure 3) and can
include a simple beep or alerting tone or a series of pre-recorded
voice messages.
It will also be appreciated that the alert unit 24
provides the flexibility to have the viewer alerted by substituting
3 0 (on channels other than the detailed message channel) the override
audio signal 64 for a specified period, e.g. before or during the
display of the one line message.
2~.0~223
-24-
By utilizing the scheduling manager 26, the display of
emergeney announcements by the alerting system 10 can be
controlled on the basis of the channel profile database 27, for
example, the programming schedule and requirements of the cable
television station 20 which have been loaded or stored in the
database 27. As discussed above, the controller/demodulator 22 is
coupled to the scheduling manager 26. In its simplest form, the
scheduling manager 26 comprises the database 27 and the controller
29. The database 27 has a record for each of the cable channels being
1 o televised by the station 20. Each record contains information
pertaining to the programming or status of the corresponding cable
channel. For example, if it is desired to block an emergency
announcement during the playing of a commercial endorsement,
the record can include a "commercial-in-progress" flag. When a
~ 5 command packet for an emergency announcement is received, the
controller 29 checks or polls the "commercial-in-progress" flag. If
the flag is set, i.e. a commercial is being televised, the controller 29
will wait until the flag is reset before sending the message to alert
unit 24. The commercial-in-progress flag will be reset once the
2 o commercial has ended. A priority interrupt level can also be
specified using the dynamic tag byte in the command packet (Figure
5). For example, if the priority level is high, the controller 22 will
not block the emergency announcement even though the commercial-
in-progress flag is set.
2 5 The scheduling manager 26 can also be used to
implement the "day-parting" feature as introduced above. The day-
parting feature provides the ability to block the operation of the
. alert system 10 for a selected period of time on all or selected cable
channels. This feature can be used, for example, to block the display
3 0 of emergency announcements during regular business hours (or
during a newscast) when the newsroom of the station 20 is
operational and capable of televising the emergency
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CA 02106223 2000-O1-14
-25-
announcement. As for the commercial pre-empting feature, the
day-parting feature can be implemented by specifying a day-parting
record in the channel profile database 27 which is checked by the
controller 29 when a command/data packet is received from the
central computer 18. The day-parting feature can also be combined
with a priority hierarchy as discussed above.
As discussed above, the "commercial-in-progress" flag
and "day-parting" feature is derived from programming schedule
for each cable channel and in operation the channel profile
1 0 database 27 which represents the programming schedule for each of
the channels carried by the cable television station 20. As will be
understood by one skilled in the art, the programming schedule
comprises the times for broadcasting the feature programs and the
time slots for playing the commercial endorsements. Typically, the
1 5 programming schedule for a cable television station 20 is made up
of feature programs which have been purchased from the major
television networks and which will include some of the
commercial endorsements that have already been sold by the
television network. The programming schedule can also include
2 0 time slots for commercial endorsements which have been sold by
the cable station 20. Since the programming schedule is known
ahead of time, the channel profile database 27 can be updated ahead
of time, e.g. loaded on a weekly or even monthly basis. It will be
appreciated that this simplifies the administration of the database
2 5 27 without compromising the performance of the commercial
blocking and day-parting features of the present invention.
Referring back to Figures 4i and 4ii, the commercial
block and day-parting features can be implemented by including a
channel profile database 27 check after the command/data packet is
3 0 received from the central computer 18 and translated or formatted
by the controller 22 prior to the alert unit 24, so that the command
can be blocked if necessary. This processing loop is indicated by
CA 02106223 2000-O1-14
-26-
arrows 301 and 303 in Figures 4i and 4ii. The check can
implemented in a software program running on the controller 29
as a routine which queries the channel profile database 27
whenever a command/data packet is received from the central
computer 18 for a channel, indicated generally by block 500 in
Figures 4i and 4ii. The other features associated with the channel
profile database 27, e.g. priority, postal code check and traffic
logging, can also be implemented in analogous fashion.
Reference is made to Figure 6 which shows in flow
1 0 chart form typical logical processing steps for the programming
manager routine 500 for implementing the commercial block and
day-parting features discussed above. Once the controller 22 has
decoded a command/data packet received from the central
computer 18, the routine looks up the record for the cable channel
1 5 in the scheduling manager 27 at block 502. In block 504, the routine
500 checks the record for the commercial-in-progress flag. If the flag
is set, then the routine 500 moves to block 506 which determines if
the commercial can be interrupted by a high priority message. If the
commercial cannot be pre-empted (at block 506), then the routine
2 0 waits till the commercial has ended. If a commercial is not in
progress (commercial blocking is not active), then the routine
moves to block 508. In block 508, the routine checks the cable
channel record in the scheduling manager 27 to determine if day-
parting has been activated. If day-parting is active, i.e. programming
2 5 cannot be interrupted, then the routine will wait for another
command/data packet from the central computer 18. On the other
hand, if day-parting is not active, i.e. emergency notification
permitted, then the routine will proceed to block 512 which returns
processing of the command/data packet to the alerting unit 2 (see
3 0 Figure 4), as indicated by line 303.
Although the messages to be displayed have been
referred to as being emergency warning messages, they can of
CA 02106223 2000-O1-14
-27-
course be any messages considered to be of over-riding public
interest, for example, news flashes or messages concerning
important sporting events such as the World Series.
The present invention may be embodied in other
specific forms without departing from the spirit or essential
characteristics thereof. For example, the controller/demodulator
and interface controller can be combined. The presently disclosed
embodiments are therefore to be considered as illustrative and not
restrictive, the scope of the invention being indicated by the
1 0 appended claims rather than the foregoing description, and all
changes which come within the meaning and range of equivalency
of the claims are therefore intended to be embraced therein.
2~~~~z3
-28-
APPENDIX
Command Message Specifications
Command Type: Tag Setup Message
External controller 22
Destination
Channel microcontrollers 70
This message specifies the Channel Dynamic Tag for
108 channels, which is the maximum number for an alert unit 24.
The first byte applies to the first channel on the first board of the
t 5 addressed alert unit 24, while byte 36 applies to the fourth channel
of the ninth board.
The tag assigned to any channel overwrites the
previous Tag set for that channel. That is, a channel responds only
one Dynamic Tag value at a time.
2 0 Notwithstanding the above, a channel will always
respond to a message containing a Tag equal to zero, which is used
to broadcast messages to all channels in the system. A channel will
also respond to the proper physical Tag.
2 5 ~ ' .;
byte # description
0 One byte identifying the target alert unit box:
1 = first box in the daisy chain
2 = second box
3 0 3 = third box
1... from 4 to 36 by bytes rnrresponding to the quantity of
channel boards 28 installed in the chassis.
Image
~~~~~z3
-~0-
Channel microcontrollers 70
.tiQn
The alert unit 24 is capable of displaying static or
scrolling lines and pages of text. To simplify the data management
on the channel board 28, all of the data will be manipulated using
the concept of lines of text.
A total of 240 lines of 24 characters are stored and
0 available per channel board 28. Each character requires two bytes of
data, as described in the data sheet for the Rohm character
generator 72, giving a total channel board requirement of just
under 12 Kbytes.
The lines to be used in contiguous operations (e.g.
t 5 scrolling and crawling) are always completely filled by the central
computer 18, except for the last line, where an end-of-line/end-of
page will be indicated by the 16 bit value xx80. This corresponds to
unused bit D7 in the (Rohm) character generator 72; it will always
be zero except for the EOL/EOF condition. This mark will be used
2 o by scrolling/crawling operations.
byte # description
0 One byte identifying the line number (1- 240)
2 5 1 ... 48 24 charatcters, using two bytes each.
Command Type: Control messages
External controller 22
-31~~-06~~3
Each alert unit 24 channel is uniquely controlled by
this type of message. A single message contains a complete
definition of the data to act upon, the start and stop conditions,
bypass switch 42,44 (Figure 2) conditions, and the transition from
the active operation to the next one.
There is no queuing of operations for a cable channel.
One operation may be in progress, and another one may be waiting.
o If a control packet arrives while a prior one is waiting, then the
waiting packet is replaced with the new one. The operation in
progress is not interrupted unless the new message so specifies.
~ 5 byte # description
0 The first line of text upon which to act:
0 don't care
1 ... 240 Line 1 to 240
1 The line number on the display screen at which to
2 o show the first line of text:
1 ... 10 Line number, where 1 is the first line at the top
of the screen
2 The display characteristics set to be used in this
operation:
2 5 0 don't care
1 ... 5 Setup data ID
3 The operation to be performed:
0 don't care
1 Display as static line
3 0 2 Display contiguous lines horizontally scrolling
3 Display as static page
4 Display contiguous lines as pages vertically
~r
y y ~r:
f4
31:;~'.es~... ....
2~~~223
7 Bypass relay 42,44 (Figure 2) conditions to assume at
Start of operation (see below)
8 Bypass relay 42,44 (Figure 2) conditions to assume at
2 o Stop of operation (see below)
In the bypass relay conditions field, bit #7 is used to indicate don't
care (i.e. = 0) or active (i.e. = 1). One of the other bits will
correspond to bit #C in the Rohm character generator 72 (Figure 2)
definition to be used with this operation. The other bit can be
2 5 defined during the alert unit 24 implementation. The net result is
to provide relay and character generator combinations which allow
channel video and audio to be bypassed with the relay,
superimpose text over channel video, superimpose text over
replacement video, or use replacement video and/or audio.
~~.~~~23
_~_ ,
External eontroller 22
Destination
Channel microcontrollers 70
Description
This message is used to load a second version of
operating software into the channel microcontrollers 70. Each
message contains a physical address, followed by a series of bytes to
o be loaded starting at the address.
It is the responsibility of the controller 22 device to
correctly place the software in the microcontroller 70 program
address space.
Write protection for memory areas which should not
15 be overwritten by operating software may be implemented as
required.
byte # description
2 0 0 ...1 16 bit address (high byte first) at which to start loading
the following series of bytes.
2 ... 50 Up to 48 bytes of data.
2 5 Command Type: Software Activation
External controller 22
3 0 I~gt~jQp
Channel microcontrollers 70
;~.;,.;,,.:
~.:~.,.,:.,..
2IQ~~.~~
_~_
Qescription
This message is used to switch software execution to
the previously loaded software. It contains only a physical
address
at which to start execution
This message may also be used to cause a soft reset by
jumping to the firmware entry point.
Data format
byte # description
0 ...1 16 bit physical address (high byte first) at which to
start
execution.
Command Type: Health Query
Source '
if request: External controller 22
if response: Channel Microcontrollers 70 ,
2 o if request: Channel Microcontrollers 70
if response: External controller 22
l~
This message is used with a Physieal Tag, and requests
2 5 a reply with the curient status of the corresponding channel
board;
28 (Figure 2) i.e., the same reply is expected for the four
channels on
the same board 28 (Figure 2).
The reply rnntains the status of the microcontroller 70
plus ariy other board/channel status which may be defined during
3 0 the design stage.
It is the responsibility of the controller 22 to regulate
status requests, in order to avoid collisions due to multiple
A ... , . ' ' y . . , .. . . . . , , . .
. . . .
.
~~.~~~~3
the backplane Reset line 54 (Figure 2).
This message is not forwarded to the channel boards.
Image
