JP3000933B2 - Diversity switch 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 diversity switch device, and more particularly to a heterodyne type television relay broadcasting device having a function of separating a video signal and an audio signal and adjusting a video / audio power ratio. The present invention relates to a suitable diversity switch device.

[0002]

2. Description of the Related Art In diversity switching of a television relay broadcasting device, the input levels of two signals S _V1 and S _V2 entering diversity in FIG.
In detecting each compared in the comparison circuit 55 the level V _L1, V _L2 of the detected two signals, to detect signals larger reception level. At this time, the vertical synchronizing signals V _V1 and V _V2 are extracted from the video signals S _V1 and S _V2 by the vertical synchronizing detection circuits 52 and 54 in parallel. Then, the comparison circuit 5
5 and the vertical synchronization detection circuits 52 and 54
Switching control circuit 5 _converts the vertical synchronization signals V _V1 and V _V2 detected by
6 so that the switching operation of the switch 60 can be performed within the vertical retrace period of the selected signal. Thus, by performing the switching operation of the switch 60 within the vertical blanking period of the video signal, a stable image can be obtained. Such a conventional example is disclosed in
No. 0780 is also disclosed.

[0003]

However, in the above-mentioned conventional example, the switching operation is performed within the vertical blanking period of the video signal, so that "image" stability can be obtained. There is a disadvantage that noise generated at the time of switching cannot be suppressed.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the disadvantages of the prior art and, in particular, to provide a diversity switch device which minimizes the sound switching noise generated when a switch is switched.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a signal separating section for separating each audio signal from each television signal received by a plurality of antennas, And an audio switching unit that switches the switches so that the audio signal having the highest signal level is selectively output from the audio signals separated by the above. Of these,
The audio switching unit performs another switching while the signal level of the audio signal on which switching has been set once is equal to or higher than a preset threshold level .
The signal level of at least one audio signal is
Is higher than the signal level of the audio signal
Also has a switching prohibiting means for prohibiting the switch from being switched.

Therefore, according to the first aspect of the present invention,
When the signal level of each audio signal is lower than the threshold level, the audio switching unit selects and outputs the audio signal having the highest signal level. On the other hand, if the level of the audio signal that was selected because the signal level was the highest until then further increases and exceeds the threshold level, while the signal level of the audio signal is equal to or higher than the threshold level, the level of the other audio signal is increased. Does not switch even if the level exceeds the level of the currently selected audio signal, the output of the currently selected audio signal is maintained as it is. Thus, unnecessary switching of the switch is suppressed.

According to the second aspect of the present invention, a signal separating section for separating each audio signal from each television signal received by the two antennas, and a signal level from each of the audio signals separated by the signal separating section. And a sound switching unit that switches the switch so that the largest sound signal is output. Of these, the side voice switching unit, which was once the switch setting
For more than a threshold level at which the signal level is both predetermined audio signal of the signal level and the other audio signal is adopted a configuration that includes a switching inhibition means for inhibiting the said switch is switched.

For this reason, in the invention according to claim 2 ,
When one or both signal levels of the audio signals are below the threshold level, the audio switching unit selects and outputs the audio signal having the highest signal level. On the other hand, if each audio signal exceeds the threshold level, while the signal level of each audio signal is equal to or higher than the threshold level, even if the level of the audio signal not selected and output exceeds the level of the audio signal being selected and output. The switch is not switched, and the output of the currently selected audio signal is maintained as it is. This allows
Unnecessary switching of the switch is suppressed.

According to the third aspect of the present invention, the above-described threshold level is set to L which is a value that does not cause a practical problem with the audio reference level.
_When " ₀ " is set, it is set to about " L0-6 " dB.

[0010] Therefore, in the invention according to claim 3,
By setting the threshold level of the audio signal to a low level within a range in which there is no practical problem, switching of the switch is prevented as much as possible.

Accordingly, the above-mentioned object is to be achieved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG.

The diversity switch device shown in FIG. 1 includes antennas 1 and 2 for receiving television signals S _T1 and S _T2.
And conversion circuits 3 and 4 for converting the received television signals S _T1 and S _T2 into an intermediate frequency band, and converting the frequency band converted television signals S _T1 and S _T2 into video signals S _V1 and S _V2 and audio signals, respectively. Separation circuits 5 and 6 for separating the _signals into S _A1 and S _A2 are provided. Among them, the conversion circuits 3 and 4 and the separation circuits 5 and 6 constitute a signal separation unit 21. The diversity switch device selectively outputs one of the two audio signals S _A1 and S _A2 , and selectively outputs one of the two video signals S _V1 and S _V2. Switch 60, an audio switching control circuit 7 for controlling the switching of the switch 9, a video switching control circuit 50 for controlling the switching of the switch 60, the selected video signal _SV and the audio signal S _A.
And a synthesizing circuit 11 for synthesizing. Here, the audio switching control circuit 7 and the switch 9 constitute an audio switching unit 22.

In this embodiment, the video switching control circuit 5
The configuration of 0 is the same as the configuration of FIG. 3 shown as a conventional example. That is, the video signal separated by the signal separation unit 21 S _V1, S and level detecting circuit 51 and 53 for detecting the signal level V _L1, V _L2 of _V2, the video signal S _V1, S vertically from _V2 synchronizing signal V _A vertical synchronization detection circuit 52 for extracting _V1 and _VV2 ,
54, a comparison circuit 55 for determining the video signal having the highest signal level from the outputs of the level detection circuits 51 and 53, and a comparison based on the vertical synchronization signals V _V1 and V _V2 detected by the vertical synchronization detection circuits 52 and 54. A switching control circuit for performing a switching operation of the switch within a vertical blanking period of the video signal determined by the circuit.

FIG. 2 is a block diagram of the audio switching control circuit 7. The audio switching control circuit 7 includes a signal separation unit 21
The signal levels A _L1 and S _{L1 of} the audio signals S _A1 and S _A2 separated by
A level detection circuit 13 and 12 for detecting the _L2, the level detecting circuits 12 and 13 the signal level detected by the A _L1,
A switching control unit 14 that outputs a switching signal _SKA to the switch 9 so that the audio signal having a higher signal level is selected and output by comparing A _L2, and each signal level detected by the level detection circuits 12 and 13. A switching prohibition control circuit 15 that outputs a control signal for prohibiting switching of the switch 9 to the switching control circuit 14 while at least one of the signal levels of A _L1 and A _L2 is equal to or higher than a preset threshold level. .

In the present embodiment, the above-mentioned threshold level is set to “L ₀ −6 ” dB when the voice reference level is L ₀ . Here, the audio reference level L ₀
The reason for setting the threshold value 6 dB lower than that is to prevent the switching of the switch as much as possible by setting the threshold level of the audio signal to a low level within a practically acceptable range.

Next, the overall operation of the above embodiment will be described.

Referring to FIG. 1, antennas 1 and 2 receive the same TV channel signal. Antenna 1,
The television signals S _T1 and S _T2 received at 2 are input to conversion circuits 3 and 4, respectively, and are converted into intermediate frequency bands. For example, Fv = 17.75 MHz, Fa = 22.25 MH
is converted to z. Thus, the received television signal S
_{Since T1} and _ST2 are converted into intermediate frequencies by the conversion circuits 3 and 4, there is no problem even if the received TV channel signals are different. Thereafter, the television signals whose frequency bands have been converted are input to separation circuits 5 and 6, respectively, and separated into audio signals S _A1 and S _A2 and video signals S _V1 and S _V2 . The level ratio between the video signal and the audio signal is, for example, 4: 1. The separated video signals S _V1 and S _V2 are input to the video switching control circuit 50. The separated audio signals S _A1 and S _A2 are
The signal is input to the voice switching control circuit 7.

Next, referring to FIG. 3, the video signals S _V1 and S _V2 input to the video switching control circuit 50 are input to level detection circuits 51 and 53, respectively, and the signal levels (detection output levels) V _L1 and V _{L1 are} output. V _L2 is detected. At the same time, the video signals S _V1 and S _V2 are also input to the vertical synchronization detection circuits 52 and 54, and the vertical synchronization signals V _V1 and V _V2 are extracted.
The extracted vertical synchronization signals V _V1 and V _V2 are input to the switching control circuit 56, respectively. The outputs of the signal level detection circuits 51 and 53 are input to a comparison circuit 55, and a signal having a higher received signal level is selected. This selection result is reported to the switching control circuit 56. Then, the switching control circuit 56 switches the switch 60 within the vertical synchronization section of the video signal selected by the comparison circuit 55 as in the conventional example. As a result, the switch 60 sequentially selects and outputs the higher one of the video signals S _V1 and S _{V2 from} the higher signal level, and inputs the selected signal to the synthesis circuit 11 in FIG.

Next, referring to FIG. 2, the audio signals S _A1 and S _A2 input to the audio switching control circuit 7 are input to level detection circuits 12 and 13, respectively, and the signal levels A _L1 and S _A1 are input.
A _L2 is detected. Detected signal levels A _L1 , A
_L2 is the switching control circuit 14 and the switching prohibition control circuit 1
5 is input. It is determined whether each of the signal levels A _L1 and A _L2 input to the switching inhibition control circuit 15 is equal to or larger than a preset threshold level. While any one of the signal levels is equal to or higher than the threshold level, the control signal S _S for prohibiting the switching of the switch 9 is input from the switching prohibition control circuit 15 to the switching control circuit 14. Further, the switching control circuit 14
The signal levels A _L1 and A _L2 input to the switch 9 are compared in magnitude, and the switching signal S _KA of the switch 9 is selected so that the audio signal having the higher signal level is selectively output via the switch 9. Output. At this time, the switching inhibition control circuit 15
When the control signal S _S for prohibiting the switching of the switch 9 is input to the switch 9, the switching control circuit 14 does not output the switching signal S _{KA to} the switch 9.

[0021] According to this, when both are below a threshold level of the signal level A _L1, A _L2 of the sound signal S _A1, S _A2, the high signal level of the two audio signals S _A1, S _A2 Is selected and output via the switch 9. On the other hand, when one of the signal levels increases and exceeds the threshold level, while the signal level is maintained at or above the threshold level, the level of the other audio signal exceeds the threshold level and the audio that is already selected Even if the signal level is exceeded, the switch 9 is not switched, and the output of the selected audio signal is maintained.

Here, when the signal level of one audio signal exceeds the signal level of the other audio signal and becomes equal to or higher than the threshold level, the switching control circuit 14 outputs the switching signal _SKA to the switch 9 rather than outputting the switching signal _SKA to the switch 9. Fast switching prohibition control circuit 15
Situation in which the control signal S _S for switching inhibition are inputted to the switching control circuit 14 is also conceivable. In this case, there may be a disadvantage that the selected output of the audio signal whose signal level does not exceed the threshold level is maintained as it is. Therefore, it is desirable to provide a delay circuit at the output stage of the switching inhibition control circuit 15 for the control signal S _S.

Apart from this, when the two signals S _A1 and S _A2 are input as in this embodiment, when the detection output level is both equal to or higher than the threshold level, the comparison circuit 14 outputs the switching inhibition signal S
Separate the switching sends _S switch 9, when either or both of the detector output level coming into the switch prohibition control circuit 15 is lower than the threshold level does not output a switching inhibition signal S _S, the switch 9 may be permitted.

The audio signal S selectively output from the switch 9
_A and the video signal S _V selectively output from the switch 60 are
Are input to the respective combining circuits 11, are restored to television signals S _T as an output signal.

As described above, according to the present embodiment, the switching prohibition control circuit controls the switch 9 for switching the audio signal while at least one of the input audio signals is at or above the preset threshold level. When the audio signal currently selected and output reaches the minimum signal level that can be used, the switching operation of the switch is suppressed, and unnecessary switching noise can be prevented. It is possible to reduce voice switching noise. The threshold level is set to (L ₀ −6) dB with the audio signal level set to L ₀ , so by setting the threshold level to a low level within a range where there is no practical problem, the switching of the switch is suppressed as much as possible. can do.

Here, in the present embodiment, the case of _two input signals S _T1 and ST ₂ has been described, but the same applies to the case of two or more inputs.

[0027]

Since the present invention is constructed and functions as described above, according to the first aspect of the present invention, the switching inhibiting means sets the signal level of at least one of the input audio signals in advance. While it is above the set threshold level,
Since the switching of the switch for switching the audio signal is prohibited, when the currently selected and output audio signal reaches the minimum practicable signal level, the switching operation of the switch is suppressed, and unnecessary switching noise is suppressed. Generation can be prevented, and noise of voice switching can be reduced.

[0028] According to the second aspect of the present invention, the audio switching unit includes:
Since the switch is prohibited from switching while the signal level of each audio signal is equal to or higher than a preset threshold level,
When two audio signals are input and the currently selected audio signal reaches the minimum practicable signal level, the switching operation of the switch is suppressed,
Unnecessary switching noise can be prevented from being generated, and voice switching noise can be reduced.

According to the third aspect of the present invention, the threshold level is set to about (L ₀ −6) dB assuming that the audio signal level is L ₀ , so that the threshold level is set to a low level within a practically acceptable range. Can be suppressed so that the switching is not performed as much as possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a voice switching control circuit in FIG. 1;

FIG. 3 is a block diagram showing a conventional example and showing a configuration of a video switching control circuit in FIG. 1;

[Explanation of symbols]

1, 2 antenna 9, 60 switch 15 switching inhibition control circuit (switching inhibition means) 21 signal separation unit 22 audio switching unit A _L1 , A _L2 audio signal signal level S _A1 , S _A2 audio signal S _T1 , S _T2 television signal

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-64097 (JP, A) JP-A-60-165879 (JP, A) JP-A-57-79739 (JP, A) JP-A-2- 7724 (JP, A) JP-A-7-183875 (JP, A) JP-A-8-163452 (JP, A) JP-A-4-119180 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 7/00 H04B ⁷ /02-7/12 H04L 1/02-1/06 H04N 5/00-5/00 101

Claims (3)

(57) [Claims] 1. A signal separation unit for separating each audio signal from each television signal received by a plurality of antennas, and an audio signal having the highest signal level is selectively output from each audio signal separated by the signal separation unit. And a voice switching unit that switches a switch as described above, wherein the voice switching unit is configured such that the signal level of the voice signal once switched and set is equal to or higher than a preset threshold level. ,
The signal level of at least one other audio signal is
Is higher than the signal level of the audio signal
But the diversity switch device characterized in that it comprises a switching inhibition means for inhibiting the said switch is switched. 2. A signal separation unit for separating each audio signal from each television signal received by two antennas, and an audio signal having the highest signal level is selectively output from each audio signal separated by the signal separation unit. A voice switching unit that switches a switch so that the voice signal is switched.
During the signal level and higher signal levels are both preset threshold level of other audio signals, the diversity switching apparatus characterized by comprising a switching inhibition means for inhibiting the said switch is switched. Wherein said threshold level, the actual voice reference level
Assuming that L ₀ is a value that does not cause any practical problems , about “L ₀ −
6. The diversity switch device according to claim 1, wherein the diversity switch device is set to 6 " decibels.