 |
Description  |
|
|
BACKGROUND OF THE INVENTION
This invention relates to a CATV system and a CATV terminal unit for use
therein, comprising a head end (center) which re-transmits broadcast waves
of existing stations or transmits independently produced programs and a
number of terminal units connected to the center via cables.
Conventionally, a center (head end) apparatus in the CATV system of this
type comprises a VHF antenna, a UHF antenna, and a BS antenna for
receiving broadcast waves of existing stations. The broadcasting signals
received by these antennas are respectively processed and mixed before
being transmitted via a transmission line, e.g., a coaxial cable.
The center apparatus also comprises sources for independently produced
original programs, such sources including a video camera, a video cassette
recorder (VCR) or the like. The system selects such sources for
transmission of the produced signals via the cable.
The center apparatus determines, according to a broadcasting schedule of
programs, from which source the signal is obtained, modulates a TV signal
from the selected source to have a specific channel frequency, and mixes
the TV signal with other signals before transmitting them via the
transmission line.
Further, the center apparatus transmits data, such as a channel and
permission or prohibition for receiving a specific program, to a
subscriber terminal unit in the form of an FSK signal on a channel
prepared in advance.
On the other hand, each CATV terminal unit has an address unique to itself,
by which only the terminal unit belonging to a subscriber having a
contract to receive chargeable programs is allowed to receive the
chargeable programs. Such a terminal unit selects a desired signal from
signals transmitted via the transmission line, descrambles the selected
signal if the selected signal carries a chargeable program and was
scrambled by the center apparatus, and modulates the descrambled signal to
have a specific channel frequency of a television receiver, e.g., channel
3 or channel 4, before outputting the signal. The FSK signal transmitted
as out-of-band data from the center apparatus is subjected to a
predetermined process and then is used to generate a control signal for a
control of a descrambling operation.
The CATV terminal unit further comprises an input unit provided in the main
body and a remote control unit separately supplied as an input unit.
Operation of either input unit activates execution of channel selection,
setting operation of a timer (a time at which the terminal unit power is
turned on), or the like.
In the above-mentioned general arrangement of a CATV system, the timer
function of the CATV terminal unit may sometimes be used as a VCR
recording timer, an alarm timer, or a sleep timer.
In the above-mentioned CATV system and CATV terminal unit therefor, when
the subscriber uses the timer function of the terminal unit to reserve a
program, it is necessary to input such data as the channel number of the
program, the date, the turning-on time, and the turning-off time. This is
a cumbersome operation involving a number of steps.
On the other hand, the actual broadcasting time of a "realtime" program
such as a sporting event or other live programming may be subject to
change due to a change of the start time or end time of the event. If a
timer reservation has been set to such a program, but the actual starting
or ending time is different from what was scheduled, it may occur that the
timer-on function will be activated when the reserved program has not yet
started. In this case, the subscriber typically waits before the TV
receiver for the reserved program to start. Alternatively, it may occur
that a part of the program will be missed because of the difference
between the times selected by the timer unit and the actual broadcast time
of the program.
SUMMARY OF THE INVENTION
The present invention is intended to provide a solution to the above
problems. An object of the invention is to provide a CATV system and a
CATV terminal unit therefor which allows the operation for timer
reservation of a program to be relatively simple and which ensures that a
reserved program will be received even when the broadcasting time of the
reserved program has changed.
To solve the above problems, a CATV system according to this invention
comprises a center apparatus which transmits a program and data specifying
the program and the program channel at the start of each program; and a
CATV terminal unit having the capability of reserving a program and being
connected to the center apparatus via a transmission line. The CATV
terminal unit comprises memory means for storing data representing a
reserved program, which data is input at the time of reserving a program;
and control means for comparing the data from the center apparatus with
the data stored in the memory means, determining the start of the reserved
program based on the result of the comparison, and controlling the
reception of the reserved program.
The CATV terminal unit receives the program and the data specifying the
program and the channel of the program from the center apparatus at the
start of the program, and comprises input means for inputting data
specifying a reserved program; memory means for storing the data input
from the input means; and control means for comparing the received data
with the data stored in the memory means, determining the start of the
reserved program based on the result of the comparison, and controlling
the reception of the reserved program.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing an embodiment of a CATV system according
to this invention;
FIGS. 2 and 3 are drawings showing examples of a timer start command and a
timer end command, respectively, transmitted from the center apparatus of
FIG. 1;
FIG. 4 is a flowchart of the operations performed by the controller of the
CATV terminal unit of FIG. 1; and
FIG. 5 is a drawing showing an example of the CATV program list to be used
in conjunction with this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
There now follows a description of embodiments according to this invention
with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of the CATV system
according to this invention. The CATV system shown in the figure comprises
a center (head end) apparatus 1, a transmission line 2, e.g., a coaxial
cable, and a number of CATV terminal units 3 connected to the center
apparatus 1 via the transmission line 2.
Center apparatus
The center apparatus 1 comprises a VHF antenna 11, a UHF antenna 12, and a
BS antenna 13, each of which receives broadcasting signals from existing
broadcasting stations. The broadcasting signals received by the VHF
antenna 11 and UHF antenna 12 are supplied to respective signal processing
circuits 14 and 15, while a broadcasting signal received by the BS antenna
13 is supplied to a signal processing circuit 17 via a BS tuner 16. The
signal processing circuits 14, 15 and 17 process the broadcasting signals
received by the corresponding antennas 11 to 13, and these broadcasting
signals processed by the signal processing circuits 14, 15 and 17 are
mixed by a mixer 18, and then transmitted by the CATV terminal units 3 via
the transmission line 2.
The center apparatus 1 also comprises, as signal sources for broadcasting
independently produced programs, a video camera 19, video cassette
recorders (VCR) 20a and 20b. The latter signal sources are connected to a
switching means or switcher 21, which selects a signal source and
transmits a TV signal from the selected signal source to a TV modulator
22. The TV modulator 22 converts the video signal from the selected video
source to a specific channel frequency and supplies the
frequency-converted video signal to the mixer 18.
The switcher 21 is controlled according to a program broadcasting schedule
by a system controller 24 via a schedule controller 23. Namely, a specific
signal source is selected by the schedule controller 23 which switches the
switcher 21 under the control of the system controller 24. To this end,
the schedule controller 23 transmits data from the system controller 24 to
the switcher 21 according to the program broadcasting schedule and causes
the switcher 21 to select from among the several signal sources, the one
which will be connected to the TV modulator 22. The TV signal from the
signal source selected by the switcher 21 is modulated to have a specific
channel frequency by the TV modulator 22 and mixed with other signals by
the mixer 18 before being transmitted via the transmission line 2.
Furthermore, the system controller 24 automatically outputs timer commands
of such formats as shown in FIGS. 2 and 3 at the start and end times of
the program broadcast. Additionally, the controller 24 outputs data
representing the channel of the broadcast and permission or prohibition
data designating whether terminal units are permitted to descramble the
program. The channel permission and prohibition data is the same as is
conventionally provided in CATV systems with chargeable programming. The
latter data and the former timer commands are transmitted on a channel
prepared in advance via an FSK data transmitter 25 and the mixer 18. The
timer command to be transmitted at the start of broadcasting consists of a
timer start command ID code, a program number, and a channel number, as
shown in FIG. 2, while the timer command to be transmitted at the end of
broadcasting consists of a timer end command ID code and a program number,
as shown in FIG. 3.
An input unit 26, comprising, e.g., a keyboard, and a memory unit 27
comprising, e.g., a RAM and a ROM, are connected to the system controller
24. The input unit 26 is used by an operator to input program broadcasting
schedule data and to select either an automatic mode for making a fully
automatic selection of the signal source in the center apparatus 1
according to the program broadcasting schedule or a manual mode for making
a switching selection. The memory unit 27 comprises a ROM for storing a
control program of a CPU in the system controller 24, and a RAM for
storing data such as a program broadcasting schedule received from the
input unit 26. The data stored in the RAM of this memory unit 27 is read
by the system controller 24, and used, e.g., to automatically switch
between broadcasting programs or to transmit the timer command data.
The above-mentioned manual mode is used when the function of the system
controller 24 to automatically transmit the timer command as programmed is
stopped. In this mode, the operator can freely transmit the timer command
when the program is extended or starts later than scheduled.
CATV Terminal Unit 3
The CATV terminal unit 3 includes a timer reservation function such as a
VCR recording timer, an alarm timer, or a sleep timer. The terminal unit 3
comprises a converter 31 for selecting a desired signal from the number of
broadcasting signals which are transmitted via the transmission line 2 and
frequency-converts the selected signal; and a descrambler 32 for
descrambling a signal selected by the converter 31 if the selected channel
carries a chargeable program and the signal of the program is scrambled by
the center apparatus 1. The descrambled signal is frequency adjusted to be
on a specific channel of a television receiver 4, e.g., channel 3 or
channel 4.
In addition to the above, the CATV terminal unit 3 comprises a branching
device 33 for branching a part of the broadcasting signal at the upstream
stage of the converter 31 to obtain the FSK signal transmitted as out-band
data from the center apparatus 1; an FSK data receiver 34 for separating
the FSK signal from the broadcasting signal branched by the distributor
33; and a controller 35, consisting, e.g., of a CPU, to which the FSK
signal obtained by the FSK data receiver 34 is supplied.
The controller 35 comprises a keyboard provided in the main body and a
separately supplied remote control unit. Units connected to the controller
35 include an input unit 36 which is operated by a subscriber to input a
command such as a turn command or a channel selection command; a display
unit 37 for displaying the input command data input by the input unit 36;
and a memory unit 38. The memory unit 38 comprises a ROM for storing a
control program for the controller 35 and a RAM for storing data such as
the command data input by the input unit 36 and the data transmitted as
the FSK signal from the center apparatus 1.
Operation of the Terminal Unit
To time reserve a program for timer recording or timer watching, the CATV
terminal unit 3 is operated by inputting a program number, indicated on
the program list distributed to the subscriber, in advance of the
broadcast of the program using function keys or ten keys of the input unit
36. For example, to input a program number 1234, it is only required that
a "timer" key, ten keys "1", "2", "3", "4" and a "setting" key be
operated. When the program number "1234" has been input by this key
operation on the input unit 36, this program number is stored in a
predetermined area in the RAM of the memory unit 38 after being converted
to a corresponding code for a purpose of later comparison with program
number data transmitted from the center apparatus 1.
When a timer start command (FIG. 2) is received from the center apparatus
1, the controller 35 compares the program number in this timer start
command with the program number stored in the RAM of the memory unit 38 by
the timer reservation and judges whether or not the two program numbers
are identical. If they are identical, the controller turns on the main
power of the terminal unit 3, stores the received channel number in a
predetermined area of the RAM, and based on the channel number, generates
tuning data, such as a dividing ratio data of a PLL, to select the
appropriate channel whose channel number is included in the timer start
command, and provides this data to the converter 31. It will be
appreciated that the predetermined storage area in storage unit 38, is an
area which represents the current channel number. That stored number
controls the controller to generate the necessary inputs to the converter
so the converter will select the channel corresponding to the channel
number stored in the predetermined area. At the time a time unit start
command is received, and if the program number received matches the stored
program number, the received channel number will replace the previously
held channel number stored in said predetermined area. The latter channel
number will be stored in another location until the timer reserved program
is finished, at which time the said previous channel number will be again
stored in the predetermined location.
Upon receipt of a timer end command (FIG. 3) by the CATV terminal unit 3,
the controller 35 compares the program number stored in the RAM of the
memory unit 38 with the program number in the timer end command. If the
two numbers are identical, the controller 35 erases the channel number
stored in said predetermined area of the RAM and causes the storing unit
38 to store in the same area the channel number which was previously saved
in another location of the memory. This returns the CATV terminal unit 3
to the state before the receipt of the timer start command. The controller
then turns off the main power of the terminal unit 3 to complete a series
of operations associated with the timer reservation.
Detailed Operation
The operation of the CATV terminal unit 3 will now be described in detail
with reference to the flowchart in FIG. 4 showing the job to be performed
by the CPU in the controller 35 of the CATV terminal unit 3 according to a
predetermined program.
The flowchart indicates an operation of the CPU which starts with the
turning on of the standby power for the CPU. In step S1 a determination is
made as to whether there is a keyed input from the input unit 36. If there
is no keyed input, the CPU proceeds to step S2, where it is determined,
based on a signal from the FSK data receiver 34, whether or not a timer
start command has been received from the center apparatus 1. If no timer
start command has been received, the CPU proceeds to step S3, where it is
determined whether or not a timer end command has been received. If the
judgment in S3 is NO, the CPU returns to step S1 to repeat the above
steps.
If there is a keyed input from the input unit 36, the judgment in S1 is
YES, and the CPU proceeds to step S4, where it is determined whether or
not the keyed input is related to a timer reservation, i.e., whether there
has been a series of inputs starting with the "timer" key and ending with
the "setting" key. If the judgment is NO, the CPU proceeds to another
keyed input judgment step (not shown) not related to the present
invention. If the judgment in step S4 is YES, i.e., the keyed input is
related to a timer reservation, the CPU proceeds to step S4', where the
program number keyed in is converted to a code representing the program
number, and the CPU further proceeds to step S5. In step S5 the CPU causes
the memory unit 38 to store in the RAM the program number input by the
keyed input from the input unit 36, and returns to step S1.
On the other hand, if the judgment of step S2 is YES, i.e., the timer start
command has been received from the center apparatus 1, the CPU proceeds to
step S6, where it compares the program number in the timer start command
(FIG. 2) with the program number stored in the RAM of the memory unit 38,
and further proceeds to step S7 to determine whether or not the two
program numbers are identical. If the judgment in step S7 is NO, i.e.,
there is no program number stored in the RAM of the memory unit 38 which
is identical with the program number in the timer start command, the CPU
returns to step S1 and repeats the above-mentioned steps.
If the judgment in step S7 is YES, i.e., the program number identical with
the program number in the timer start command has been stored in the RAM
of the memory unit 38, the CPU proceeds to step S8. In step S8 the channel
number stored in a predetermined area in the RAM of the memory unit 38
which stores the current channel number is saved in another part of the
memory unit, and the channel number in the timer start command is stored
in the predetermined area of the RAM. Also in step S8, the main power of
the terminal unit 3 is turned on, and the operation returns to step S1 to
repeat the above mentioned operation.
Upon execution of the above step S8, the tuning data for selecting a
channel based on the channel number included in the timer start command,
such as division ratio data of the PLL, is transmitted to the converter
31, and the channel of the desired program is selected.
If the determination in step S3 is YES, i.e., the timer end command has
been received, the CPU proceeds to step S9, where it compares the program
number in the timer end command (FIG. 3) with the program number stored in
the RAM of the memory unit 38, and further proceeds to step S10 to
determine whether or not the two program numbers are identical. If the
determination in step S10 is NO, i.e., there is no program number stored
in the RAM of the memory unit 38 which is identical with the program
number in the timer end command, the CPU returns to step S1 with this end
command regarded as an end command for another program.
If the determination in step S10 is YES, i.e., the program number identical
with the program number in the timer end command has been stored in the
RAM of the memory unit 38, the CPU proceeds to step S11, where it erases
the channel number stored in the predetermined area in the RAM of the
memory unit 38 which stores the current channel number, and causes the
memory unit 38 to store in the same area the channel number which was
previously saved in step S8. The CPU then turns the power off and returns
to step S1 and completes a series of operations associated with the timer
reservation.
Modified Embodiment
In the above embodiment the timer start command has distinct program
numbers and channel numbers. However, if the program numbers are defined
as including respective channel numbers, as shown in FIG. 5, separate
channel numbers need not be included in the timer start command. However,
it will be appreciated that whether or not a separate channel number is
included in the start command, the information about the channel will be
included in the start command. Moreover, only one timer command is needed,
if a number which is not used as a program number, e.g., "999999", is
defined and used as the timer end command ID code.
As described above, the present invention not only allows the program
reservation operation to be simple but also ensures that any program whose
broadcasting time has been changed can be received correctly from its
start.
* * * * *
|
|
 |
|
 |
Description |
|
