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DESCRIPTION JP2003092537

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DESCRIPTION JP2003092537
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
wireless microphone system provided with a wireless microphone and a dedicated receiver.
[0002]
2. Description of the Related Art In wireless microphones, the input sensitivity is adjusted
according to the volume of a speaker or the like. This adjustment is performed by manually
operating the switch of the attenuator attached to the wireless microphone, the gain adjustment
volume of the microphone amplifier provided in the wireless microphone, and the like.
[0003]
However, it is difficult to make an optimal adjustment by grasping the volume of the speaker and
the habit of speaking, and considerable training is required to be able to perform such an
adjustment. is necessary. For example, if the gain setting of the microphone amplifier is too small
with respect to the volume of the speaker, the S / N ratio may be degraded or the volume may be
insufficient. If the setting of gain is too large, problems such as distortion of speech occur.
Therefore, it was difficult to ensure good voice quality if this adjustment did not rely on the
operator who was familiar with handling the wireless microphone system.
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[0004]
An object of the present invention is to provide a wireless microphone system capable of
automatically adjusting the gain automatically and a method of setting sensitivity in this system.
[0005]
SUMMARY OF THE INVENTION A wireless microphone system according to the present
invention comprises a wireless microphone and a receiver.
The wireless microphone comprises a microphone. An audio signal from the microphone is input
to the first gain adjustment means, and a gain adjusted audio signal is output. As the first gain
adjustment means, a variable attenuator or variable gain amplifier can be used. Control means
generates a control signal in response to the input signal of the first gain adjustment means or
the level of the gain adjusted speech signal. A modulation means outputs a modulated signal in
which the carrier wave is modulated by the control signal and the gain adjusted speech signal
from the first gain adjustment means following it. The modulation means may modulate the
carrier wave by the control signal itself, or may modulate the control signal to, for example, a
tone signal, and may modulate the carrier wave by the tone signal. The receiver comprises
demodulation means. Demodulation means demodulates the modulated signal into the control
signal and the gain adjusted speech signal. The demodulated gain adjusted speech signal is input
to a second gain adjusting means, and the second gain adjusting means is controlled by the
demodulated control signal. When the gain of the first gain adjusting means is increased at the
same timing based on the control signal and the demodulated control signal, the first and second
gain adjusting means may be a second gain adjusting means. Lower the gain of Alternatively,
when the gain of the first gain adjusting means is lowered, the gain of the second gain adjusting
means is increased. That is, the first and second gain adjusting means have their gains adjusted
in a complementary manner, and the output level of the second gain adjusting means is
controlled to be a predetermined value.
[0006]
In this wireless microphone system, in the wireless microphone, the gain of the first gain
adjusting means is adjusted based on the level of the audio signal from the microphone or the
gain adjusted audio signal from the first gain adjusting means. Ru. This gain adjustment is such
that the S / N ratio of the gain-adjusted speech signal from the first gain adjustment means
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becomes good or distortion is caused in the gain-adjusted speech signal based on the volume of
the speaker or the like. It is set not to occur. When the voice signal whose gain is adjusted by the
first gain adjustment means set in this way is transmitted to the receiver and demodulated as it is
at the receiver, the signal level becomes too large to cause distortion or the signal level is small.
Too much, the S / N ratio may deteriorate. Therefore, the second gain adjustment means of the
receiver performs gain adjustment just reverse to the gain adjustment in the first gain adjustment
means, and outputs an output signal of a predetermined level to the second gain adjustment
means. . Moreover, since the gain adjustment of such first and second gain adjustment means is
performed at the same timing by the wireless microphone and the receiver, after adjustment, the
total gain from the wireless microphone to the output of the receiver is calculated. It can be
constantly kept constant. Note that this adjustment can be performed each time the speaker is
changed, or can be performed at predetermined intervals.
[0007]
In the method for setting sensitivity of a wireless microphone system according to the present
invention, first, an audio signal level in the wireless microphone is detected to generate a control
signal. Next, the control signal is transmitted from the wireless microphone to a receiver. At the
same timing after the transmission, when the gain of the gain adjustment means provided in the
wireless microphone is increased in the wireless microphone based on the control signal, the
receiver is provided in the receiver based on the transmitted control signal. Decrease the gain of
the gain adjustment means. Alternatively, when the gain of the gain adjustment means provided
in the wireless microphone is reduced in the wireless microphone based on the control signal at
the same timing after the transmission of the control signal, the receiver transmits the signal
based on the transmitted control signal. The gain of the gain adjustment means provided in the
receiver is increased. Such complementary gain adjustment in the wireless microphone and the
gain adjustment means of the receiver brings the level of the output signal of the gain adjustment
means of the receiver to a predetermined level. After gain adjustment of the wireless microphone
and the gain adjustment means of the receiver is performed, transmission of an audio signal from
the wireless microphone is started.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION A wireless microphone system according to a
first embodiment of the present invention comprises a wireless microphone 2 as shown in FIG. 1
(a) and a receiver as shown in FIG. 1 (b). It is equipped with four.
[0009]
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The wireless microphone 2 has a microphone 5.
The audio signal from the microphone 5 is supplied to a first gain adjustment means, for
example, a variable attenuator, specifically a PAD (programmable attenuator) 6. The voice signal
attenuated by the PAD 6 is amplified by an amplification means, for example, a microphone
amplifier 8 and then supplied to a compressor and pre-emphasis circuit 10, and after
compression and pre-emphasis processing, modulation means, for example, RF modulation It is
supplied to the amplifier 12. Here, the output signal of the compressor and pre-emphasis circuit
10 is modulated, for example, FM-modulated, and the carrier wave of a predetermined frequency
is transmitted from the antenna 14. The above configuration is common to a normal wireless
microphone.
[0010]
In the wireless microphone 2, gain control of the PAD 6 is performed based on the level of the
audio signal of the microphone amplifier 8 at a predetermined timing. That is, the audio output
signal of the microphone amplifier 8 is supplied to the A / D converter 16, where it is
sequentially converted into a digital audio signal and supplied to control means, for example, the
CPU 18. The CPU 18 detects the peak value or average level of each digital audio signal supplied
within a fixed time. Based on this detected value, a control signal, for example, a gain control
signal, which makes the level of the audio output signal from PAD 6 a predetermined value, is
determined. The gain control signal is supplied to the PAD 6 and to the tone signal generator /
modulator 20, where it is modulated to a tone signal and supplied to the RF modulation amplifier
12. The RF modulation / amplifier 12 FM-modulates the carrier based on the tone signal and
transmits it from the antenna 14. The supply timing of the gain control signal to PAD 6 will be
described later.
[0011]
The wireless receiver 4 shown in FIG. 1 (b) has an antenna 22. The modulation signal from the
wireless microphone 2 received by the antenna 22 is demodulated into an audio signal or a tone
signal by the reception / demodulation unit 24 including, for example, a high frequency
amplification unit, a frequency conversion unit, an intermediate frequency amplification unit, and
a detection unit.
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[0012]
The audio signal is supplied to a de-emphasis expander circuit 26, where de-emphasis processing
and expansion processing are performed, and supplied to a second gain adjustment means, for
example, a variable gain amplifier 28, where it is amplified. Then, the signal is output from the
output terminal 30.
[0013]
On the other hand, the tone signal demodulated is supplied to a tone signal demodulator 32,
where it is demodulated into a gain control signal and supplied to control means, for example, a
CPU 34.
The demodulated gain control signal is supplied to the gain adjustment unit 36 of the variable
gain amplifier 28. The gain adjustment unit 36 controls the gain of the variable gain amplifier 28
based on the gain control signal.
[0014]
In the wireless microphone system configured as described above, as shown in FIG. 2, the output
sound level of the microphone amplifier 8 is detected in the wireless microphone 2 during a fixed
period up to the time t1, and based on this, at the time t1. The value of the gain control signal is
determined. The value of the gain control signal can control PAD 6 to a level at which an
appropriate S / N ratio can be secured without causing distortion in the output level of
microphone amplifier 8.
[0015]
From time t1 to time t2, a modulation signal obtained by modulating the carrier wave from the
wireless microphone 2 by the gain control signal is transmitted to the receiver 4.
[0016]
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The receiver 4 which has received this modulated signal demodulates the received modulated
signal from the time t2 to the time t3 and supplies it to the CPU 34.
The CPU 34 converts the demodulated control signal into a gain control signal that can be
supplied to the gain adjustment unit 36. On the other hand, from time t2 to time t3, the wireless
microphone 2 is in a standby state until preparation at the receiver 4 is completed.
[0017]
At time t3, the gain control signal is supplied from the CPU 18 to the PAD 6 in the wireless
microphone 2, and the gain control signal from the gain adjustment unit 36 is variable at the
same timing in the receiver 4, ie, at time t3. It is supplied to the gain amplifier 28. Thus,
adjustment of the PAD 6 and the variable gain amplifier 28 ends at time t4.
[0018]
Here, as is apparent from the comparison of FIGS. 2A and 2B, the gain adjustment of the variable
gain amplifier 28 in the receiver 4 and the attenuation adjustment of the PAD 6 in the wireless
microphone 2 are complementary to each other. The relationship is being done.
[0019]
That is, the sound signal input to the wireless microphone 2 is large, and as shown in the first
half of FIG. 2A, the output of the PAD 6 is attenuated so that the level is lowered by a than the
predetermined PAD reference level. The amount adjustment is performed (as a result, the output
level of the microphone amplifier 8 of the wireless microphone 2 becomes a predetermined
value), and the sensitivity of the wireless microphone 2 is reduced.
In this case, if the receiver 4 does not change the output level while the sensitivity is lowered, the
output level becomes smaller, and the transmission content can not be spread with good quality.
In order to compensate for this decrease in sensitivity, the gain of the variable gain amplifier 28
is increased such that the output level of the variable gain amplifier 28 of the receiver 4 is larger
than the predetermined receiver reference level by a (this results in The output level of the
variable gain amplifier 28 of the receiver 4 becomes a predetermined receiver reference level).
Normally, when the speakers of the wireless microphone 2 are identical, the transmission volume
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does not change significantly, so by adjusting the wireless microphone 2 and the receiver 4
automatically in this way, good voice quality can be obtained. The speaker's transmission content
can be expanded.
[0020]
Alternatively, as shown in the second half of FIG. 2A, for example, the speaker is changed from
the above-described state reduced by a from the wireless reference level, and the voice input
level to the wireless microphone 2 is small. In the case where it is not shown, although the level
detection is performed and the voice input level is found to be small as described above, the level
is increased by b from the above state in order to increase the level at PAD6. The amount of
attenuation at PAD 6 is reduced so that the state is achieved (as a result, the output level of
microphone amplifier 8 of wireless microphone 2 becomes a predetermined value). That is, the
sensitivity of the wireless microphone 2 can be increased. If this is received by the receiver 4 as
it is, the output level of the variable gain amplifier 28 becomes too large, and the content of the
transmission can not be amplified with good quality. Therefore, the output level of the variable
gain amplifier 28 of the receiver 4 is lowered by b from the state where the level is increased by
a from the receiver reference level to compensate for this, and the output level of the variable
gain amplifier 28 Is a predetermined receiver reference level. By this, it is possible to expand the
transmission content of the speaker with good quality.
[0021]
Since the PAD 6 and the variable gain amplifier are controlled in the complementary relationship
at the same timing as described above, the total gain from the wireless microphone 2 to the
receiver 4 is always kept constant.
[0022]
A wireless microphone system according to a second embodiment is shown in FIG.
In this system, as shown in FIG. 6A, in place of the PAD 6 of the wireless microphone 2, a
microphone amplifier 8a composed of a variable gain amplifier of the wireless microphone 2a is
used. The gain of the microphone amplifier 8a is controlled based on the gain control signal from
the gain adjustment unit 8b. The control signal is supplied from the CPU 18 to the gain
adjustment unit 8 b, and the gain adjustment unit 8 b generates a gain control signal based on
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the control signal. The CPU 18 makes a determination based on the digital voice signal as in the
case of the gain control signal in the first embodiment. This control signal is supplied as it is to
the RF modulation / amplifier 12 to modulate the carrier wave. A modulated signal generated by
this modulation is transmitted to the receiver 4a.
[0023]
In the receiver 4a, the reception demodulation unit 24 demodulates the modulation signal into a
control signal and supplies the control signal to the CPU 34. The CPU 34 supplies this control
signal to the gain adjustment unit 36, and the gain adjustment unit 36 adjusts the gain of the
variable gain amplifier 28. Adjustment of the gains of the microphone amplifier 8a and the
variable gain amplifier 28 is performed in the same manner as the gain adjustment of the PAD 6
and the variable gain amplifier 28 of the first embodiment.
[0024]
In the wireless microphone system of the second embodiment, the carrier wave is directly
modulated by the control signal on the side of the wireless microphone 2a without converting
the control signal into a tone signal. Therefore, the tone signal generator / modulator 20 is
unnecessary, and the tone signal demodulator 32 is unnecessary in the receiver 4a, and the
configuration of both the wireless microphone and the receiver can be simplified.
[0025]
In the first embodiment described above, the gain control signal to PAD 6 is determined based on
the output signal of PAD 6, but can be determined based on the input signal to PAD 6. Similarly,
the gain of the microphone amplifier 8a in the second embodiment is also determined based on
the output signal of the microphone amplifier 8a, but may be determined based on an input
signal to the microphone amplifier 8a.
[0026]
As described above, according to the present invention, a control signal for level adjustment is
generated at the wireless microphone side, which is also transmitted to the receiver side, and at
the same timing, the wireless microphone and the wireless microphone Since the level
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adjustment is performed complementarily in the receiver, the total gain from the wireless
microphone to the receiver can be kept constant after the level adjustment.
[0027]
Brief description of the drawings
[0028]
1 is a block diagram of a wireless microphone and a receiver of the wireless microphone system
of the first embodiment of the present invention.
[0029]
2 is a timing diagram of the wireless microphone system of FIG.
[0030]
3 is a block diagram of a wireless microphone and a receiver of the wireless microphone system
of the second embodiment of the present invention.
[0031]
Explanation of sign
[0032]
Reference Signs List 2 2a wireless microphone 4 4a receiver 6 PAD (first gain adjustment means)
12 RF modulation / amplifier (modulation means) 18 CPU (control means) 24 reception /
demodulator (demodulation means) 28 variable gain amplifier (second) Gain adjustment means)
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