JP2954822B2 - Equipment for joint hearing facilities - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device used at a head end or the like in a public hearing facility, and more particularly to a device for converting an input signal into an intermediate frequency signal.

[0002]

2. Description of the Related Art Conventionally, devices used for the above head end include, for example, a signal processor and a converter. For example, these convert a television broadcast wave received by an antenna into an intermediate frequency signal in a first frequency conversion section, amplify the intermediate frequency signal in an intermediate frequency amplification section, and convert the amplified intermediate frequency signal into a second frequency signal. Is converted to a desired frequency by the frequency converter and supplied to the transmission line of the joint hearing facility. As the first and second frequency converters and intermediate frequency amplifiers, those having an automatic gain control function are used.

[0003]

However, in such a device, the broadcast wave may end or the broadcast wave may be interrupted on the way due to the convenience of the broadcast station. In such a case,
If the first and second frequency conversion units and the intermediate frequency amplification unit have an automatic gain control function, noise other than broadcast waves is excessively amplified and supplied to the transmission line. Such devices include:
It is rare that only a unit is provided, and a plurality of units are often used at the same time. In such a case, since the amplified noise is combined with a signal from another device receiving the broadcast wave on the transmission line, the broadcast wave measured at the terminal of the joint hearing facility is received. There is a problem that the C / N ratio of a signal from another device is deteriorated. In addition, inquiries from users of each terminal as to whether the joint hearing facility is out of order,
There was also a problem that the administrator of the co-hearing facility had to deal with it.

To improve the C / N ratio only, for example, a squelch circuit may be provided in an intermediate frequency amplifier or the like. But,
In this case, since the broadcast wave cannot be received by the terminal, a situation where the user mistakenly thinks that the joint hearing facility is at fault is still not solved. Also, when a sub head-end device is installed in the middle of a transmission path of a joint hearing facility, a squelch circuit similar to the above is required. Generally, in a joint hearing facility, adjacent channel transmission is often performed, and it has been difficult to easily install a squelch circuit.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a first frequency converting means for receiving broadcast waves and converting the frequency to a first frequency, and a first frequency converting means. An intermediate frequency signal path including intermediate frequency amplifying means for amplifying the output signal of the first and second frequency conversion means; a second frequency conversion means for frequency-converting the output signal of the intermediate frequency signal path to a second frequency;
Information signal generating means for generating a predetermined information signal having the same frequency as the intermediate frequency signal; wave stop detecting means for generating a detection signal when the broadcast wave stops; Switching means for supplying the information signal to the frequency signal path.

Further, the first frequency converting means, the intermediate frequency signal path, the second frequency converting means, the stop detecting means, and the switching means are provided as one set, and a plurality of these sets are provided. One information signal generating means is provided in common for the signal path.

[0007]

According to the present invention, in each set, the broadcast wave is frequency-converted into the first intermediate frequency signal by the first frequency converting means, and is amplified by the intermediate frequency amplifying means in the intermediate frequency signal path. The frequency is converted to the second frequency by the frequency conversion means. When the broadcast wave is stopped due to the end of the broadcast or the interruption of the broadcast due to the failure of the broadcast station, the stop is detected by the stop detecting unit, and a detection signal is generated.
In response to this detection signal, the switching means supplies the information signal from the information generating means to the intermediate frequency signal path. Therefore, the information signal is converted into a signal of the second frequency by the second frequency conversion means and output. Therefore, information represented by the information signal, for example, characters or voices indicating the suspension of broadcasting is output to the terminal of the joint hearing facility.

This information signal is supplied from information signal generating means provided only once in each group.

[0009]

FIG. 1 shows a first embodiment. This example is
For example, the present invention is applied to a signal processing device in a head end, and includes three sets of signal processing devices 2a, 2b, and 2c.

The signal processing device 2a has an input terminal 4a to which a VHF band television broadcast signal received by, for example, a VHF band receiving television antenna (not shown) is inputted. Of the television broadcast signal of the VHF band input amplifier 6a and the first local oscillator 8
a to the first frequency conversion means 5a.
The VHF band input amplifier 6a receives the first local oscillation signal from the first local oscillation unit 8a, converts the frequency of the VHF band television broadcast signal into an intermediate frequency signal having a predetermined frequency, amplifies the signal, and amplifies the intermediate frequency signal. The signal is supplied to an intermediate frequency amplifying unit, for example, an intermediate frequency amplifying unit 10a existing in the path.

The intermediate frequency amplifying section 10a amplifies and outputs the frequency-converted intermediate frequency signal. The intermediate frequency amplifying unit 10a may separate the intermediate frequency signal into a video intermediate frequency signal and an audio intermediate frequency signal, amplify these to respective predetermined levels, and combine and output them.

The output signal of the intermediate frequency amplifier 10a is
Switching means, for example, the fixed contact 14 of the changeover switch 12a
a, VHF band output amplifying section 18a via movable contact 16a
And the second local oscillation section 20a. VHF band output amplifier 18a
Receives the second local oscillation signal generated by the second local oscillation section 20a, converts the frequency of the intermediate frequency signal into a desired VHF band frequency, amplifies the signal, and outputs the amplified signal to the transmission line of the joint hearing facility. I do. The frequency of the VHF band to be frequency-converted may be the same as the frequency of the VHF band television broadcast signal supplied to the input terminal 4a, or may be another frequency.

Note that at least one of the VHF band input amplifier 6a, the intermediate frequency amplifier 10a and the VHF band output amplifier 18a may have an automatic gain control function.

The fixed contact 22a of the changeover switch 12a is supplied with an information signal obtained by modulating a signal from an information signal generating means 25, for example, a signal generating section 26 by an intermediate frequency modulating section 27 via a four-way divider 24. . Information signal generating means 2
Reference numeral 5 denotes a signal generating unit 2 including, for example, a video signal generator for generating a character image “currently broadcasting is stopped” and an audio signal generator generating an audio signal for “currently broadcasting is stopped”.
6 and a modulator 27 that modulates a carrier having the same frequency as the intermediate frequency signal with these signals to generate an information signal.

Part of the intermediate frequency signal generated by the VHF band input amplifier 6a is supplied to a detection circuit 28a, where the level of the intermediate frequency signal is detected. This level detection signal is supplied to the switching control circuit 30a and compared with the reference signal. The reference signal has, for example, a level of an intermediate frequency signal which is a boundary between a state in which a VHF band television broadcast signal is input to the VHF band input amplifier 6a and a state in which the VHF band television broadcast signal is not input. When the television broadcast signal is input, the normal changeover switch 12
When the movable contact 16a is connected to the fixed contact 14a (on the side of the intermediate frequency amplifier 10a) and no television broadcast signal in the VHF band is input, the changeover switch 1
The movable contact 16a of 2a is connected to the fixed contact 22a side (the distributor 24
Side, i.e., switched to an intermediate frequency modulator 2 7 side). That is,
The detection circuit 28a and the switching control circuit 30a constitute a wave stop detection unit.

Therefore, when a VHF band television broadcast signal is input to the input terminal 4a, the switching control circuit 30a switches the movable contact 16a of the changeover switch 12a to the fixed contact 14a side. 6a, the intermediate frequency signal amplified by the intermediate frequency amplifier 10a is supplied to the VHF band output amplifier 18a, where it is frequency-converted into a predetermined VHF band television broadcast signal. It is transmitted to the transmission line of the hearing facility.

On the other hand, when the broadcast from the broadcasting station has ended,
When the VHF band television broadcast signal input to the input terminal 4a is stopped due to the fact that the broadcast is interrupted due to a failure in the broadcast station or the like, the switching control circuit 30a
The movable contact 16a is switched to the fixed contact 22a. As a result, the information signal generated by the information signal generating means 25 and supplied to the fixed contact 22a via the four divider 24 is supplied to the VHF band output amplifying section 18a, where the predetermined VHF band television broadcast is transmitted. The signal is frequency-converted and transmitted to the transmission line of the public hearing facility.

Therefore, at the terminal of the joint hearing facility,
The viewer who has watched the television broadcast of the frequency of the output signal from the VHF band output amplifier 18a, for example, replaces the broadcast from the broadcast station up to now with, for example, the video “current broadcast is stopped” and the “current broadcast”. The user will hear the sound of "under the wave", and can know that there is no failure in the joint viewing facility. In addition, since a predetermined VHF band television broadcast signal based on such an information signal is transmitted to the transmission line of the joint viewing facility, noise is amplified and output to the transmission line of the joint viewing facility. And the output signals from the other signal processing devices 2b and 2c
The / N ratio does not deteriorate.

Similarly to the signal processing device 2a, the other signal processing devices 2b and 2c also have changeover switches 12b and 12c, detection circuits 28b and 28c, changeover control circuits 30b and 30c, first local oscillators 8b and 8c, and 2 local oscillators 20b, 20
c, but instead of the VHF band input amplifier 6a,
The UHF band input amplifying units 6b and 6c are used, and the signal processing device 2b replaces the VHF band output amplifying unit 18b with the signal processing device 2c.
Uses the UHF band output amplifying unit 18c.

Of course, the UHF band input amplifying units 6b and 6c input from the input terminals 4b and 4c are UHF band television broadcast signals received by UHF band receiving antennas. The frequencies of the signals are different.

The frequency of the intermediate frequency signal output from the UHF band input amplifiers 6b and 6c is
This is the same frequency as the frequency of the intermediate frequency signal 0a. Further, the VHF band output amplifying unit 18b and the UHF band output amplifying unit 1
The frequency of the output signal 8c is different from each other.

An information signal is supplied from the four distributor 24 to the fixed contacts 22b and 22c of the changeover switches 12b and 12c. That is, three signal processing devices 2a, 2
One intermediate frequency modulator 26 is commonly used for b and 2c. Thus, each signal processing device 2a, 2b,
Since setting the frequency of the information signal to the same frequency as the intermediate frequency signal of the same frequency at 2c, the information signal generation hands
The stage 25 can be used in common for each signal processing device 2a, 2b, 2c. Reference numeral 28 denotes a four distributor 24.
In this embodiment, only the three distribution outputs are used while using the four distributors 24 in the matching device provided in
Is provided.

In each of the signal processing devices 2b and 2c, similarly to the signal processing device 2a, when the UHF band television broadcast signal input to the input terminals 4b and 4c is stopped, the "broadcast suspension" is set. The video and the sound of “broadcast is stopped” are viewed on the terminal.

FIG. 2 shows a second embodiment. In the second embodiment, the changeover switch 12a of the signal processing device 2a is
Except for being provided on the input side of the intermediate frequency amplifier 10a,
The configuration is the same as that of the first embodiment, and operates similarly to the first embodiment. Although not shown in FIG. 2, the changeover switches 12b and 12c are also provided on the input side of the intermediate frequency amplifier 10a in other signal processing devices.

In the above embodiment, the present invention is applied to a signal processing apparatus. However, the present invention can be applied to other equipment for a joint hearing facility, such as a converter, which uses two frequency conversion means. Further, in the above embodiment, three signal processing devices are shown, but the number of used signal processing devices can be arbitrarily increased or decreased.

Further, in the above embodiment, the broadcast wave is V
HF and UHF band television broadcast signals
Satellite broadcast signals, satellite communication signals, and FM broadcast signals can also be used. Also, the detection of the level of the intermediate frequency signal for determining whether or not the broadcast wave has stopped is performed by detecting the intermediate frequency signal inside the VHF band input amplifier 6a, the UHF band input amplifier 6b, and the UHF band input amplifier 6c. The output side or the intermediate frequency amplifiers 10a, 10b, 10c
It may be performed internally or on the output side. Instead of detecting the level of the intermediate frequency signal, the level of the television broadcast signal in the VHF band and the UHF band input to the input terminals 4a, 4b, and 4c may be detected. Also, information signal generating means
The information signal from 25 is based on the video signal and the audio signal, but may be based on only one of them.

[0027]

As described above, according to the present invention, when the broadcast wave stops, an information signal having the same frequency as the intermediate frequency signal is supplied from the information signal generating means to the intermediate frequency signal path. The frequency is converted to a second frequency by the second frequency conversion means and output. Therefore, instead of the above-mentioned suspended broadcast wave on each terminal side of the joint viewing facility,
Since the information represented by the information signal is viewed, the viewer recognizes that the joint hearing facility has not failed,
Calls to the co-hearing facility manager are not flooded. Moreover, even if the broadcast wave stops, the frequency-converted information signal is supplied to the transmission line, so that no noise is supplied to the transmission line and the C / N ratio does not deteriorate. Further, according to the present invention, even when a sub head end device is provided, the squelch circuit is not required because the wave does not stop, and the cost can be reduced.

Further, since one information signal generating means is commonly used for a plurality of sets of equipment, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of a device for a joint hearing facility according to the present invention.

FIG. 2 is a partially omitted block diagram of the second embodiment.

[Explanation of symbols]

5a 5b 5c First frequency converting means 10a 10b 10c Intermediate frequency amplifying section (intermediate frequency amplifying means) 12a 12b 12c Switch (switching means) 18a 18b 18c Second frequency converting means 28a 28b 28c Detection circuit (wave stop detecting means) 30a 30b 30c Switching control circuit (wave stop detecting means) 25 Information signal generating means

Continuation of front page (56) References JP-A-55-158785 (JP, A) JP-A-54-47517 (JP, A) JP-A-5-129843 (JP, A) JP-A-5-327719 (JP) JP-A-48-3024 (JP, A) JP-A-1-256823 (JP, A) JP-A-60-72074 (JP, U) JP-B-52-19731 (JP, B2) (58) Field surveyed (Int. Cl. ⁶ , DB name) H04N 5/00 101

Claims (1)

(57) [Claims] 1. An intermediate frequency signal path including a first frequency converting means for receiving a broadcast wave and converting the frequency into a first frequency, and an intermediate frequency amplifying means for amplifying an output signal of the first frequency converting means. A second frequency converting means for converting the output signal of the intermediate frequency signal path into a second frequency, an information signal generating means for generating a predetermined information signal having the same frequency as the intermediate frequency signal, A wave-stop detecting means for generating a detection signal when the wave stops, and a switching means for supplying the information signal to the intermediate frequency signal path in response to the detection signal, a first frequency conversion means, One set of the intermediate frequency signal path, the second frequency conversion means, the detection means and the switching means is provided, and a plurality of these sets are provided, and one information signal generating means is provided in common for each set of the intermediate frequency signal paths. Joint hearing established Facility equipment.