JPS61285884A - Muting device for catv - Google Patents

Abstract

PURPOSE:To prevent the noise such as the noise sound and a picture of the noise component from being outputted from the terminal receiving equipment when the channel of a broadcasting program, which is not transmitted from a center, is selected at the terminal control part, the output to a terminal receiving equipment is muted by providing a muting means. CONSTITUTION:A CPU 18 is constituted to send the signal for muting the sound output through a signal line 25 to a sound amplifying circuit 11 based upon the output signal from a comparator 22. Namely, in a keyboard 17, the broad casting program is selected which is not transmitted from a center 1, and then, an IF.AGC voltage removed from a video amplifying circuit 14 comes to be higher than the set reference voltage and the output side of the comparator 22 comes to be an L level. For such a reason, the signal outputted from the signal line 25 of a CPU 18 also comes to be the L level and the sound output of the sound amplifying circuit 11 is muted. Consequently, the noise sound will not be generated from a television receiver 27.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a muting device for CATv (cable television). More specifically, in cases where multiple channels of broadcast programs can be transmitted from a center located at the front desk of a hotel to the guest room via cable, the terminal control unit in the guest room may display programs that are not being transmitted due to the time of day or other reasons. This invention relates to a device that mutes output to a terminal receiving device when a channel is selected.

[Prior Art] In general, multiple channels of broadcast programs transmitted from a center to each guest room via cable include system guide programs (channel 00), television retransmission programs (channel 01 to 12), etc.
channel), guide programs (channels 20 to 29),
Paid TV programs (channels 30 to 39), music programs (
40-49 channels), forced broadcast programs (50-59 channels), etc. Conventionally, in CATV systems used in hotels, etc., when a terminal control unit in the guest room selects a channel for a broadcast program that is not being transmitted from the center due to the time of day or other reasons, the output to the terminal receiving equipment is controlled. There was no mute device.

[Problems to be Solved by the Invention] For this reason, when the terminal control unit selects a channel of a broadcast program that is not transmitted from the center, the output to the terminal receiving device is not muted, and noise components are received. There was a problem.

The present invention has been made in view of the above-mentioned problems, and is designed to mute the output to the terminal receiving device when the terminal control unit selects a channel of a broadcast program that is not transmitted from the center. .

[Means for Solving the Problems] The CATV muting device according to the present invention transmits broadcast programs of a plurality of channels from a center to a terminal control unit via a cable, and transmits broadcast programs of a predetermined channel selected by the terminal control unit. is received by a terminal receiving device, the terminal control unit includes a transmission presence/absence determination means for determining whether or not a broadcast program of the selected channel is transmitted from the center, and a transmission presence/absence determination means configured to The apparatus is characterized by further comprising a muting means for muting the output to the terminal receiving device based on the non-transmission determination output.

[Embodiment] Figure 1 shows an embodiment of the present invention. In this figure, (1) is installed at the front desk of a hotel, etc., and receives broadcast programs transmitted wirelessly and/or by wire. hand,
It is a center that retransmits these, transmits independent broadcast programs, and sends and receives control signals to and from terminal equipment. Terminal control units (3,) (32) (33) installed in each guest room are connected to the center (1) via a coaxial cable (2) for mutual signal transmission. has been done.

The terminal control section (31) is configured as follows. That is, (4) converts the signal transmitted from the center (1) into a broadcast program signal (high frequency signal) consisting of a video signal and/or an audio signal, and a control signal consisting of a high frequency signal slightly lower than this high frequency signal. A tuner (6) including a PLL circuit (5) and a video IF circuit (7) are sequentially connected to the broadcast program signal output side of the divider (4). This video IF circuit (7
) on the output side are an audio IF circuit (8) and a video detection circuit (9).
) is connected to the output side of the audio IF circuit (8), and an audio detection circuit (10) and an audio amplification circuit (11) are sequentially connected to the output side of the audio IF circuit (8), and an RF
It is connected to the audio signal input terminal of the modulator (12) and also to the audio output terminal (13). The output side of the video detection circuit (9) is a video amplification circuit (14).
It is connected to the video signal input terminal of the RF modulator (12) via the RF modulator (12), and is also connected to the video output terminal (15).

The output side of the RF modulator (2) is connected to an RF output terminal (16). (17) is a keyboard equipped with a numeric keypad for channel selection and control keys such as a power key, and a CPU (central processing unit) (1g) is connected to the output side of this keyboard (17).

The output side of the CPU (18) is connected to the tuner (6).
) PLL circuit (5) and a display unit (19) equipped with an LED and a 7-segment display tube, and an interface (20) that mutually inputs and outputs parallel data.
is combined with The interface (20) includes:
It is connected to the control signal output terminal of the divider (4), converts the control signal sent from the divider (4) into serial and parallel, and outputs it from port A to the CPU (18). The control signal sent from the divider (4) through port B is converted into parallel to serial.
The control signal is output to the center (1) via the control signal output terminal of the control signal output terminal. (21) is a transmission presence/absence determination means, and this transmission presence/absence determination means (21) is a comparator (22) connected to one input terminal of the IF-AGC voltage extracted from the video amplification circuit (14). And this comparator (2
2) A resistor (
23) and a variable resistor (24), and the output side of the comparator (22) is connected to the CPU (18). The CPU (18) includes the comparator (
22) to send a signal (for example, L level signal) for muting the audio output to the audio amplification circuit (11) via the signal line (25) based on the output signal (for example, L level signal) from It is configured. It should be noted that the signal line (26) indicated by the dashed line may be configured to also send a signal for muting the video output to the video amplification circuit (14). )(3
a)... is also configured similarly to the terminal control section (31).

(27) is a television receiver as a terminal receiving device, the RF output terminal (16) is connected to the antenna input terminal of this television receiver (27), and the television receiver (27) is vacant. It is fixed to a channel (for example, 2 channels). Note that the television receiver (27) as a terminal receiving device has the audio output terminal (
13) and a monitor TV (27b) connected to the video output terminal (15).

Next, the operation of the above embodiment will be explained.

First, general effects will be explained.

When the power key of the keyboard (17) is pressed, a power switch (not shown) is turned on, and power is supplied to the terminal control unit (3,) and the television receiver (27). Further, a channel selection signal (PLL data) for channel 00 is sent from the CPU (18) to the PLL circuit (5) of the tuner (6), and the system guide program is received by the television receiver (27). At the same time, on the display section (19), the LED indicating the system guide program lights up, and the channel number "00" is displayed on the 7-segment display tube. When is pressed, the OL channel selection signal (PLL data) is sent from the CPU (1g) to the P of the tuner (6).
It is sent to the LL circuit (5) and sent to the television receiver (27
) receives the television retransmission program of channel 01. At the same time, on the display unit (19), the LED indicates that this is a TV retransmission program, and the 7-segment display tube displays the channel number "01". The same applies to the reception of guide programs on channels 20 to 29. Also, use the keyboard (17) to select 30 to 39 of pay TV programs.
When a channel key of one of the channels is pressed, a tuning signal (PLL data) of the corresponding channel is sent from the CPU (1g) to the PLL circuit (5) of the tuner (6), and the television A pay TV program on a corresponding channel is received by the receiver (27). At the same time, the corresponding LED and channel number are displayed on the display section (19). At this time, CPU (18)
Bay data (P
AY DATA) is sent to the center (1). Therefore, the center (1) side can grasp the pay TV broadcast reception on the guest room side.

As mentioned above, the keyboard (17) of the terminal control unit (31)
) is being transmitted from the center (1), the IF-AGC voltage taken out from the video amplifier circuit (14) is set by the resistor (23) and variable resistor (24). Since it is lower than the reference voltage, the output side of the comparator (22) is at H level. Therefore, the signal output from the signal line (25) of the CPU (18) also becomes H level, and the audio output of the audio amplifier circuit (11) is not muted.

Now, when a broadcast program that is not transmitted from the center (1) is selected on the keyboard (17), the IF-AGC voltage taken out from the video amplification circuit (14) becomes higher than the set reference voltage, and the comparator The output side of (22) becomes L level. Therefore, the signal output from the signal line (25) of the CPU (18) also goes to L level, and the audio output of the audio amplifier circuit (11) is muted. Therefore, no noise is generated from the television receiver (27). Note that when the video output of the video amplification circuit (14) is also muted using the signal lines (25) and (26), no video due to noise components is output from the television receiver (27).

In the above embodiment, the transmission presence/absence determining means (21) determines whether or not transmission is occurring from the center (1) by comparing the IF-AGC voltage taken out from the video amplification circuit (14) with a reference voltage. However, the present invention is not limited to this, and the present invention is not limited to this.
), it may be determined whether or not transmission is being made from the center (1) by comparing the magnitude of the electric field strength input to the center (1) or by the presence or absence of a synchronization signal.

[Effects of the Invention] Since the CATV muting device according to the present invention is configured as described above, when the terminal control unit selects a channel of a broadcast program that is not transmitted from the center, the output to the terminal receiving device is muted. This makes it possible to prevent noise such as noise sounds and noise component images from being output from the terminal receiving device.

[Brief explanation of drawings]

The drawing is a block diagram showing an embodiment of a CATV muting device according to the present invention. (1)...Center, (2)...Cable, (3t
)(3g)(33)...Terminal control unit, (18)...
CPU (Central Processing Unit), (21)... Transmission presence/absence determination means, (27)... Television receiver (@non-receiving device).

Claims (3)

[Claims] (1) In a device in which broadcast programs on multiple channels are transmitted from a center via a cable to a terminal control unit, and the broadcast program on a predetermined channel selected by the terminal control unit is received by a terminal receiving device, the terminal control unit a transmission presence/absence determination means for determining whether or not the broadcast program of the selected channel is being transmitted from the center; and an output to the terminal receiving device based on a determination output of non-transmission by the transmission presence/absence determination means. A muting device for CATV, characterized in that it is provided with a muting means for muting. (2) The terminal control unit is equipped with an AGC function, and the transmission presence/absence determination means compares the AGC voltage with a preset reference voltage, and determines the presence or absence of transmission from the center based on this comparison output. Claim No. 1
The CATV muting device described in Section 1. (3) The muting means mutes the audio output of the audio amplification circuit based on the non-transmission determination output by the transmission presence/absence determination means. ting device.