JP2775579B2 - Television broadcast signal processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television broadcast signal processing device for changing the frequency of a television broadcast signal, such as a channel processor used in a head-end device of a public hearing facility, and more particularly to such a device. The present invention also relates to an audio signal including a digital sub-audio signal.

[0002]

2. Description of the Related Art In a conventional channel processor, a frequency converter (not shown) converts a television broadcast signal of a predetermined channel received by an antenna (this television broadcast signal includes a video signal and an audio signal). After being converted into a television broadcast intermediate frequency signal including a video intermediate frequency signal and an audio intermediate frequency signal, it is supplied to an input terminal 2 shown in FIG. This television broadcast intermediate frequency signal is
After being amplified by the amplifier 4,
Be distributed. One of the divided outputs is supplied to a band-pass filter 8 having a pass band from which a video intermediate frequency signal can be extracted. The video intermediate frequency signal extracted by the band pass filter 8 is amplified by the amplifier 10 to a predetermined level.

[0003] The other split output of the two splitter 6 is supplied to a band-pass filter 12 having a pass band from which an audio intermediate frequency signal can be extracted. Note that the band-pass filter 1
2 is set to be narrower than the pass band width of the band pass filter 8. The audio intermediate frequency signal extracted by the band-pass filter 12 is amplified by the amplifier 14 to a predetermined level (this level is lower than the level of the video intermediate frequency signal output from the amplifier 10).

[0004] The video intermediate frequency signal and the audio intermediate frequency signal from the amplifiers 10 and 14 are mixed by a mixer 16 and the mixed output is again amplified by an amplifier 18 to obtain a mixed output, that is, the video intermediate frequency signal and the audio. After removing unnecessary signals by a band-pass filter 20 having a pass band capable of passing both of the intermediate frequency signals, the signals are amplified again by the amplifier 22 and supplied to the output terminal 24. The video intermediate frequency signal and the audio intermediate frequency signal are supplied from the output terminal 24 to a frequency converter (not shown), and are converted again into a television broadcast signal of a desired channel.

[0005]

Incidentally, in the UK and Scandinavian countries, the NICAM728 system is adopted to multiplex digital stereo sound with terrestrial television broadcasting. This can be achieved by moving from the video carrier as shown in FIG.
An audio carrier is arranged at a frequency higher by 5 MHz, this audio carrier is FM-modulated with an audio signal, and 0.35 MHz is higher than the audio carrier (5.85 MHz is higher than the video carrier).
A digital voice carrier is arranged at a high frequency, and the digital voice carrier is DQPSK modulated to transmit digital voice data.

When a television broadcast signal on which such a sound multiplexing is performed by the NICAM728 system is processed by the channel processor shown in FIG. 3, a part of the digital sound signal is cut by the band-pass filter 12 having a narrow band. Is done. For this reason, there has been a problem that it becomes impossible to receive stereo sound satisfactorily. As a method of solving such a problem, for example, it is conceivable to widen the pass band width of the band pass filter 12 or shift the upper and lower frequencies of the pass band. However, in this case, the band-pass filter 12 may also extract the video signal of the adjacent channel, and in the case of the television broadcast intermediate frequency signal not including the digital audio signal, it is impossible to perform the so-called adjacent transmission. Become. That is, a dedicated channel processor must be prepared for processing a television broadcast intermediate frequency signal including a digital audio signal and for processing a television broadcast intermediate frequency signal not including the digital audio signal.

[0007]

In order to solve the above-mentioned problems, the first aspect of the present invention includes a video signal and an analog audio signal having a frequency apart from the video signal, or additionally includes the video signal. An input terminal to which a television broadcast signal including a digital audio signal having a frequency distant from the analog audio signal is input on the opposite side to the signal; a first and a second input terminals which receive the television broadcast signal on the input side; A switching means for switching to any one of the second output sides, an output terminal, a signal path having one end connected to the first output side of the switching means and the other end connected to the output terminal, Distributing means for distributing the television broadcast signal transmitted to a second output side of the means, a first band-pass filter for extracting the video signal from a first distributed output of the distributing means, of First amplification means for amplifying the video signal being output from the band-pass filter to a first level, and second band-pass filter for extracting the analog audio signal from a second distribution output of the distribution means; A second amplifying means for amplifying the analog audio signal in the output of the second band-pass filter to a second level; and an output signal of the first and second amplifying means for synthesizing the other signal paths. Means for supplying to the end, between the input terminal and the input side of the switching means, the television broadcast signal provided in the signal path or between the other end of the signal path and the output terminal And a third band-pass filter to be extracted.

According to the second aspect of the present invention, a digital signal having a frequency distant from the analog audio signal on the opposite side to the video signal includes a video signal and an analog audio signal having a frequency distant therefrom. An input terminal to which a television broadcast signal including an audio signal is input; switching means for switching and sending one of the signals supplied to the first and second input sides to an output side; A connected output terminal, distribution means for distributing the television broadcast signal from the input terminal, a first band-pass filter for extracting the video signal from a first distribution output of the distribution means, A first amplifier for amplifying the video signal in the output of the first band-pass filter to a first level, and a second amplifier for extracting the analog audio signal from a second distributed output of the distributor. A band-pass filter, second amplifying means for amplifying the analog audio signal in the output of the second band-pass filter to a second level, and output signals of the first and second amplifying means. Synthesizing means for supplying to the first input side of the switching means, a signal path having one end connected to the input terminal and the other end connected to the second input side of the switching means, the input terminal and the signal A third band-pass filter provided between one end of the path, in the signal path or between the output side of the switching means and the output terminal, for extracting the television broadcast signal. .

According to a third aspect of the present invention, a digital signal having a frequency distant from the analog audio signal on the opposite side to the video signal includes a video signal and an analog audio signal having a frequency distant therefrom. An input terminal to which a television broadcast signal including an audio signal is input, and a first switch for receiving the television broadcast signal from the input terminal on an input side and switching and transmitting the signal to one of a first and a second output side Means, and one of the signals supplied to the first and second input sides is switched to the output side in conjunction with the switching operation of the first switching means, and the first input side is connected to the first input side of the first switching means. A second switching means connected to the output side of the first switching means via a signal path; an output terminal connected to the output side of the second switching means;
Distributing means for distributing the television broadcast signal sent to the second output side of the switching means;
A first band-pass filter for extracting the video signal from the divided output of the first band-pass filter, first amplifying means for amplifying the video signal in the output of the first band-pass filter to a first level, and the distributing means A second band-pass filter for extracting the analog audio signal from the second divided output of the second band-pass filter;
A second amplifying means for amplifying the analog audio signal in the output of the band-pass filter to a second level, and a second switching means for synthesizing output signals of the first and second amplifying means. Means for supplying to the input side of the first switching means and the input terminal and the input side of the first switching means, in the signal path or between the output side of the second switching means and the output terminal. A third band-pass filter for extracting the television broadcast signal.

[0010]

According to the first aspect of the invention, the television broadcast signal is switched and transmitted to one of the first and second output sides by the switching means. When the television broadcast signal includes a video signal and an analog audio signal, the switching unit switches to a state in which the television broadcast signal is transmitted to the second output side. The television broadcast signal is distributed by the distributor, the video signal is extracted from the first distributed output by the first band-pass filter, and amplified to the first level by the first amplifier. The analog audio signal is extracted from the second distribution output of the distribution unit by the second band-pass filter, and amplified to the second level by the second amplification unit. The output signals of the first and second amplifying means are combined by the combining means and supplied to the output terminal from the other end of the signal path. When the television broadcast signal includes a digital audio signal in addition to the video signal and the analog audio signal, the switching means is switched to the first output side. With this, the third band-pass filter provided between the input terminal and the input side of the switching means, in the signal path or between the other end of the signal path and the output terminal can output the video signal, the analog audio signal and the digital signal. A television broadcast signal including an audio signal is extracted and supplied to an output terminal.

According to the second aspect, the television broadcast signal is supplied to the distribution means via the input terminal and distributed. A video signal is extracted from the first distribution output by a first band-pass filter. The first amplifier amplifies the video signal being output from the first band-pass filter to a first level. A second bandpass filter extracts the analog audio signal from the second distribution output. The second amplifier amplifies the analog audio signal being output from the second band-pass filter to a second level. A synthesizing means for synthesizing the output signals of the first and second amplifying means, and
To the input side of The third band-pass filter is provided between the input terminal and one end of the signal path, in the signal path or between the output side of the switching means and the output terminal, and extracts the television broadcast signal. , To the second input of the switching means. Therefore, when the television broadcast signal includes a video signal and an audio signal, the video signal and the audio signal respectively amplified to the desired levels can be output to the output terminal by switching the switching means to the first input side. . When the television broadcast signal includes a digital audio signal in addition to the video signal and the audio signal, the television broadcast signal including the uncut digital audio signal is switched by switching the switching means to the second input side. Can be output to the output terminal.

According to the third aspect of the invention, the television broadcast signal is switched and transmitted to one of the first and second output sides by the first switching means. When the television broadcast signal includes a video signal and an analog audio signal, the first switching unit switches to a state in which the television broadcast signal is transmitted to the second output side. The television broadcast signal is distributed by the distributor, the video signal is extracted from the first distributed output by the first band-pass filter, and amplified to the first level by the first amplifier. The analog audio signal is extracted from the second distribution output of the distribution unit by the second band-pass filter, and amplified to the second level by the second amplification unit. The output signals of the first and second amplifying means are combined by the combining means and connected to the second input of the second switching means. Since the first and second switching means are interlocked, the first switching means
When the signal is switched to the output side, the second switching means supplies the signal supplied to the second input side to the output side. Therefore, the signal of the combining means is supplied to the output terminal. When the television broadcast signal includes a digital audio signal in addition to the video signal and the analog audio signal, the switching means is switched to the first output side. At this time, the second switching means is also switched to the first input side. Therefore, the third band-pass filter provided between the input terminal and the input side of the first switching means, in the signal path or between the output side of the second switching means and the output terminal provides a video signal, A television broadcast signal including an analog audio signal and a digital audio signal is extracted and supplied to an output terminal.

[0013]

In this embodiment, the present invention is applied to an intermediate frequency processing section of a channel processor. An input terminal 30 receives a television broadcast signal of a certain channel received by an antenna using a frequency converter (not shown). The frequency-converted television broadcast intermediate frequency signal is input. The television broadcast intermediate frequency signal includes a video intermediate frequency signal and an intermediate frequency signal of an analog audio signal (hereinafter, referred to as an audio intermediate frequency signal), a digital audio signal, For example, NICAM728
(Hereinafter referred to as a digital audio intermediate frequency signal).

The input terminal 30 is connected via an amplifier 32, a band-pass filter 34 and an amplifier 36 to a contact 40a of a two-circuit three-contact changeover switch 40. The band-pass filter 34 is, as shown by a two-dot chain line in FIG.
It has a pass bandwidth from which a video intermediate frequency signal, an audio intermediate frequency signal, and a digital audio intermediate frequency signal can be extracted.

The contact 40a of the changeover switch 40 is switched by a contact 40b of the changeover switch 40 between a state connected to the contact 40c and a state connected to the contact 40d. Accordingly, the television intermediate frequency signal output from the amplifier 36 is output to the contacts 40c and 40d by the switching operation of the contact 40b.

The television intermediate frequency signal output to the contact 40 d is supplied to a two-way divider 42 and is divided into two parts. One of the divided outputs is supplied to a band-pass filter 44. The bandpass filter 44 has a passband width capable of extracting a video intermediate frequency signal as shown by a dashed line in FIG.

The video intermediate frequency signal extracted by the band pass filter 44 is amplified to a predetermined level by an amplifier 46 and supplied to a mixer 48.

The other split output of the splitter 42 is supplied to a band-pass filter 50. This bandpass filter 5
0 has a pass band width that can extract the audio intermediate frequency signal as shown by the solid line in FIG. In this passband,
If the television intermediate frequency signal includes a digital audio intermediate frequency signal, a part thereof is cut off.

The audio intermediate frequency signal extracted by the band-pass filter 50 has a predetermined level (the level of the audio intermediate frequency signal is equal to the level of the video intermediate frequency signal output from the amplifier 46). Is set so as to have a predetermined ratio with respect to the weight ratio) and mixed by the mixer 48.

The mixed output of the mixer 48 is supplied to the anode side of a PIN diode 58 functioning as a part of a changeover switch 56 via a DC blocking capacitor 54. The cathode side of the PIN diode 58 is connected to the input side of the amplifier 60. Therefore, when the PIN diode 58 is conducting as will be described later, the mixed output is supplied to the amplifier 60 via the PIN diode 58, where it is amplified and supplied to the output terminal 62.

The television broadcast intermediate frequency signal generated at the contact 40c of the changeover switch 40 by operating the contact 40b (the television intermediate frequency signal is a video intermediate frequency signal,
When the audio intermediate frequency signal and the digital audio intermediate frequency signal are included, they are all extracted by the band-pass filter 34. ) Is supplied via a DC blocking capacitor 64 in the signal path 63 to the anode side of a PIN diode 66 functioning as a part of the changeover switch 56. The cathode of the PIN diode 66 is connected to the input side of the amplifier 60. Therefore, as described later, P
When the IN diode 66 is conducting, the video intermediate frequency signal, audio intermediate frequency signal and digital audio intermediate frequency signal extracted by the band-pass
0, where it is amplified and supplied to the output terminal 62.

When the output signal of the amplifier 36 is generated at the contact d of the changeover switch 40, the PIN diode 58 is turned on, and the operating current is supplied to the amplifiers 46 and 52 together.
When the output signal of the amplifier 36 is generated at the contact 40c of the changeover switch 40, the PIN diode 66 is made conductive as follows.

That is, a DC voltage of +12 V is applied to the contact 40e of the changeover switch 40, and the contact 40b is connected to the contact 4e.
0a, 40c, and at the same time, the contact 40b
The contact 40f connected to the contact 40e is connected to the anode of the PIN diode 66 via the high-frequency blocking coil 68. And this PIN diode 6
The cathode of 6 is grounded via a resistor 70.
Therefore, when the output signal of the amplifier 36 is generated at the contact 40c of the changeover switch 40, the PIN diode 66 is turned on.

The contact 40b is connected to the contacts 40a, 40d.
Is connected to the contact 40e by the contact 40b at the same time.
It is connected to the power supply units of the amplifiers 46 and 52 via 2, 74 and to the anode of the PIN diode 58 via the high frequency blocking coil 76. And this P
The cathode of the IN diode 58 is connected to the resistor 70 described above.
Grounded. Therefore, when the output signal of the amplifier 36 is generated at the contact 40d of the changeover switch 40,
While the amplifiers 46 and 52 operate, the PIN diode 58 conducts.

With this configuration, when the television broadcast intermediate frequency signal supplied to the input terminal 30 does not include the digital audio intermediate frequency signal, the contact 40b of the changeover switch 40 is connected to the contact. 40a and 4
0d and the contacts 40e and 40g are switched so that the levels of the video intermediate frequency signal and the audio intermediate frequency signal are adjusted to desired levels, respectively, as in the conventional channel processor. It can be sent to terminal 62.

When the television broadcast intermediate frequency signal supplied to the input terminal 30 includes a digital audio intermediate frequency signal, the contact 40b of the changeover switch 40 is connected to the contacts 40a and 40c. And the contact 40
When switching is performed so that e and 40f are connected, not only the video intermediate frequency signal and the audio intermediate frequency signal but also the digital audio intermediate frequency signal are extracted by the band-pass filter 34 without being cut, and these are output to the output terminal 62. Supplied. Therefore, it is possible to process a television broadcast intermediate frequency signal including or not including a digital audio intermediate frequency signal while being a single channel processor.

In the above embodiment, the band-pass filter 34
Is connected between the input terminal 30 and the contact 40a of the changeover switch 40.
It may be provided in the signal path 63 between the anode of the N diode 66, or between the connection point of the cathodes of the PIN diodes 58 and 66 and the output terminal 62.

In the above embodiment, the changeover switch 4
The output signal of the amplifier 36 is switched between the signal path 63 and the splitter 42 by using the contacts 40a, 40c, and 40d and the contact 40b.
8 and 66 by using the changeover switch 56.
8 and the signal on the signal path 63 are switched.
Only one of the contacts 40a, 40c and 40d of the changeover switch 40 and the contact 40b or the PIN diodes 58 and 66 may be provided.

That is, as shown in FIG.
Is directly connected to the amplifier 60 via the signal path 63.
And the output of the mixer 48 may be directly connected to the input of the amplifier 60. Alternatively, as shown in FIG.
To the anode side of the PIN diode 66 via
Similarly, the output side of the amplifier 36 may be connected to the input side of the splitter 42. In this case, instead of the changeover switch 40,
In order to switch and supply a voltage of DC +12 V to one of the PIN diodes 58 and 66, the high-frequency blocking coils 68 and 72
Are connected to the contacts 400a, 400b of the changeover switch 400.
Is connected to the contact 400c of the changeover switch 400.
Are connected to a DC + 12V power supply.

5 and 6, the band-pass filter 34 can be provided in the signal path 63.
Also, in FIG. 5, between the connection point between the signal path 63 and the output side of the combiner 48 and the output terminal 62, and in FIG.
The band-pass filter 34 may be provided between the connection point between the cathodes of the IN diodes 66 and 58 and the output terminal 62.

Further, in the above embodiment, the contacts 40a, 40c and 40d of the changeover switch 40 and the contact 40b are used, but an electronic switch may be used instead.

In the above-described embodiment, the audio intermediate frequency signal and the digital intermediate frequency signal have a higher frequency than the video intermediate frequency signal. In some cases, the audio intermediate frequency signal and the digital audio intermediate frequency signal may have a lower frequency than the video intermediate frequency signal.

[0033]

As described above, according to the present invention, a process suitable for a case where a digital audio signal is included in an input television broadcast signal and a process suitable for a case where a digital audio signal is not included are provided. And can be performed by one signal processing device. Therefore, there is no need to replace the signal processing device according to the television broadcast signal to be processed, and the signal processing device for processing the television broadcast signal not including the digital audio signal is replaced with the television broadcast signal including the digital audio signal. The inconvenience that arises when diverted to the above processing is eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of a signal processing device according to the present invention.

FIG. 2 is a diagram showing frequency characteristics of each band pass filter used in the embodiment.

FIG. 3 is a block diagram of an intermediate frequency signal processing circuit of a conventional channel processor.

FIG. 4 is a frequency spectrum diagram when a NICAM728 digital stereo audio signal is multiplexed with a video signal and an audio signal.

FIG. 5 is a block diagram showing an example of a modification of the above embodiment.

FIG. 6 is a block diagram showing another example of a modification of the above embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 30 input terminal 34 band-pass filter (third band-pass filter) 40 change-over switch (first switching means) 63 signal path 42 2-divider (distribution means) 44 band-pass filter (first band-pass filter) 46 amplifier (First amplifying means) 48 Mixer (synthesizing means) 50 Band-pass filter (second band-pass filter) 52 Amplifier (second amplifying means) 56 Switch (second switching means) 62 Output terminal

Claims (3)

(57) [Claims] 1. A television which includes a video signal and an analog audio signal having a frequency distant therefrom, or additionally includes a digital audio signal having a frequency distant from the analog audio signal on a side opposite to the video signal. An input terminal to which a television broadcast signal is input, switching means for receiving the television broadcast signal of the input terminal on an input side, and switching and transmitting the television broadcast signal to one of a first and a second output side; A signal path having one end connected to the first output side of the switching means and the other end connected to the output terminal; and a distribution means for distributing the television broadcast signal sent to the second output side of the switching means. A first band-pass filter for extracting the video signal from a first distribution output of the distribution means, and a first band-pass filter for amplifying the video signal in the output of the first band-pass filter to a first level. Amplifying means for extracting the analog audio signal from the second distributed output of the distributing means.
, A second amplifying means for amplifying the analog audio signal in the output of the second band-pass filter to a second level, and an output signal of the first and second amplifying means. Means for supplying the signal to the other end of the signal path, between the input terminal and the input side of the switching means, in the signal path or between the other end of the signal path and the output terminal. A television broadcast signal processing device, comprising: a third band-pass filter for extracting the television broadcast signal. 2. A video signal and an analog audio signal having a frequency distant from the video signal, or a digital audio signal having a frequency distant from the analog audio signal on a side opposite to the video signal. An input terminal to which a television broadcast signal is input, switching means for switching and sending one of the signals supplied to the first and second inputs to an output side, and an output connected to the output side of the switching means Terminals and
Distribution means for distributing the television broadcast signal from the input terminal, a first band-pass filter for extracting the video signal from a first distribution output of the distribution means, and an output of the first band-pass filter First amplifying means for amplifying the video signal therein to a first level, and a second amplifying means for extracting the analog audio signal from a second distributed output of the distributing means.
, A second amplifying means for amplifying the analog audio signal in the output of the second band-pass filter to a second level, and an output signal of the first and second amplifying means. Synthesizing means for supplying a signal to a first input side of the switching means, a signal path having one end connected to the input terminal and the other end connected to a second input side of the switching means, A third band-pass filter provided between one end of the signal path, in the signal path or between the output side of the switching means and the output terminal, for extracting the television broadcast signal; Broadcast signal processing device. 3. A television which includes a video signal and an analog audio signal having a frequency distant therefrom, or additionally includes a digital audio signal having a frequency distant from the analog audio signal on a side opposite to the video signal. An input terminal to which a television broadcast signal is input; first switching means for receiving the television broadcast signal from the input terminal on an input side and switching and transmitting the television broadcast signal to one of a first and a second output side; One of the signals supplied to the second input and the first
A second switching means having a first input side connected to a first output side of the first switching means via a signal path; and An output terminal connected to the output side of the switching means; distribution means for distributing the television broadcast signal sent to the second output side of the first switching means; and a first distribution output of the distribution means. A first band-pass filter for extracting the video signal; first amplifying means for amplifying the video signal in the output of the first band-pass filter to a first level; A second band-pass filter for extracting the analog audio signal from the distributed output; a second amplifying unit for amplifying the analog audio signal in the output of the second band-pass filter to a second level; And the output signal of the second amplifying means Means for supplying to the second input side of the second switching means, between the input terminal and the input side of the first switching means, in the signal path or the output side of the second switching means and the output. A television broadcast signal processing device, comprising: a third band-pass filter provided between the terminal and a terminal for extracting the television broadcast signal.