JP4176685B2 - Wireless microphone system characterized by squelch level setting method - Google Patents

Description

  The present invention relates to a wireless microphone transmitting apparatus and a wireless microphone receiving apparatus, and more particularly to a squelch technique suitable for an environment that receives a constant noise interference from a noise source.

A technique called squelch for removing noise in wireless communication is well known. For example, in Japanese Patent Application Laid-Open No. 9-31580, noise is output when there is no received radio wave, so when the received radio wave is reduced (the demodulated signal includes only noise components, not audio signals). ) A noise squelch that stops voice output and cuts noise is disclosed. In Japanese Patent Laid-Open No. 8-46540, a signal composed of an audio signal and a tone signal outside the audio band is transmitted, and the audio signal is output only when the tone signal is detected in the demodulated signal (the tone signal in the demodulated signal). In this case, tone squelch is disclosed. Japanese Laid-Open Patent Publication No. 9-162762 discloses a technique for setting a squelch level for turning on a squelch function (stopping an audio signal).
JP 9-31580 A JP-A-8-46540 JP-A-9-162762

  In general, in the squelch technique shown in the above-described conventional example, noise squelch instantaneously outputs noise with a loud sound due to a time lag between detection of a noise component included in a demodulated signal and stop of sound output. There is a problem. As for tone squelch, if the demodulated noise component covers a wide band, the probability that the frequency component of the tone signal is included increases, and it is mistaken for the tone signal, and the squelch function cannot be turned on. There is.

  By the way, many commercial karaoke apparatuses are accompanied by a plasma display panel (PDP) for displaying lyrics and videos and an infrared wireless microphone for singing. On the other hand, it is known that the PDP generates noise with respect to the infrared device as disclosed in JP-A-10-308705. Therefore, the karaoke device as an infrared device (microphone receiver) is affected by infrared noise generated from the inside of the PDP.

  In a karaoke store, once a karaoke device is installed, the display or the like does not move frequently. In a normal use state, the distance between the karaoke apparatus and the PDP does not change. Therefore, the level of interference given by the PDP to the wireless microphone transmission system of the karaoke apparatus is determined by the arrangement state of the karaoke apparatus and the PDP and hardly changes.

  In wireless microphone transmission systems used in such an environment, the environmental interference level is almost constant. If the squelch level is set according to the interference level, the squelch operation during normal use is appropriate. This reduces the chances of an inappropriate squelch operation that works too much or does not work.

  An object of the present invention is to provide a wireless microphone transmitting apparatus and a wireless microphone receiving apparatus that can easily optimize the setting of a squelch level, assuming a situation in which the interference level becomes substantially constant according to the use environment. is there.

The wireless microphone system according to the present invention is specified by the following items (1) to (21).
(1) A wireless microphone system including a transmission device and a reception device. (2) The transmission device includes an acoustoelectric converter, an input switch circuit, a modulation circuit, a transmission circuit, an initialization switch, and a transmission. (3) The acoustoelectric converter receives an acoustic input and outputs an audio signal. (4) The input switch circuit turns on and off the input of the audio signal from the acoustoelectric converter to the modulation circuit. (5) The modulation circuit modulates and outputs the carrier signal with the audio signal from the acoustoelectric converter or the squelch level initialization command signal from the transmission control means. (6) The transmission circuit modulates the carrier signal. The output of the circuit is converted into a radio signal and transmitted. (7) The initialization switch can input an initialization command by the user's operation. (8) When the transmission control means performs the normal transmission mode. In addition, when there is an initialization command input by the initialization switch, the normal transmission mode is switched to the initialization command mode. (9) In the normal transmission mode, the input switch circuit is turned on and modulated by the audio signal. (10) In the initialization command mode, the input switch circuit is turned off, and the radio signal modulated by the initialization command signal is output from the transmission circuit.

(11) The receiving device includes a receiving circuit, a demodulating circuit, an output switch circuit, a receiving level detecting circuit, a command detecting circuit, a noise level detecting circuit, a memory, and a receiving control means. The circuit is capable of receiving the radio signal output from the transmission circuit. (13) The demodulation circuit demodulates the output of the reception circuit and outputs an audio signal. (14) The output switch circuit is the output of the demodulation circuit. (15) The reception level detection circuit detects the reception level of the reception circuit (16) The command detection circuit detects the initialization command signal from the output of the reception circuit (17) Noise level The detection circuit detects the noise level of the output of the demodulation circuit. (18) The memory stores the squelch level. (19) The reception control means performs a normal reception mode and a command. Switching from the normal reception mode to the initialization mode when the detection circuit detects the initialization command signal (20) In the normal reception mode, the reception level detected by the reception level detection circuit exceeds the squelch level stored in the memory. (21) In the initialization mode, the reception level detection circuit detects when the noise level detected by the noise level detection circuit is above the specified level. Store the squelch level corresponding to the reception level in the memory.

  According to the wireless microphone transmitting apparatus and the wireless microphone receiving apparatus of the present invention, it is possible to accurately set a squelch level optimum for an environment affected by a certain level of interference noise. Therefore, even if it is for a moment, the interference noise is not demodulated, and noise that is acoustically output from the speaker when the signal level reaching the wireless reception device is reduced can be prevented reasonably and reliably.

  A configuration example of the wireless microphone transmitting apparatus 1 and the receiving apparatus 2 to which the present invention is applied is shown in FIG. 2 shows a control procedure of the operation of the transmission apparatus 1, and FIG. 3 shows a control procedure of the operation of the reception apparatus 2.

=== Wireless Microphone Transmitting Device 1 ===
The wireless microphone transmission device 1 includes an acoustoelectric converter 3 that converts acoustic vibration into electric vibration, an input switch circuit 4 that is interposed in an output path of an audio signal from the acoustoelectric converter 3, and an input switch circuit 4. A modulation circuit 5 to which an audio signal is input, an infrared light emitter 6 that converts the output signal of the modulation circuit 5 into an infrared wireless signal and emits it, an initialization switch 7 including an automatic return type pushbutton switch, and a microcomputer 8 And.

  The microcomputer 8 executes the control procedure shown in FIG. In a normal use state, the initialization switch 7 is not pressed (turned off). In this case, an infrared radio signal modulated by the audio signal from the acoustoelectric converter 3 is emitted from the infrared light emitter 6 (steps 202 to 203 in FIG. 2).

  When the initialization switch 7 is pushed and turned on, the microcomputer 8 recognizes this, turns off the input switch circuit 4 (step 210), and inputs an initialization command signal to the modulation circuit 5 (step 211). When the input switch circuit 4 is turned off, the audio signal from the acoustoelectric converter 3 is not input to the modulation circuit 5, and an initialization command signal is input to the modulation circuit 5 instead. At this time, an infrared signal modulated by the initialization command signal is emitted from the infrared emitter 6 (step 212).

=== Wireless Microphone Receiver 2 ===
The wireless microphone receiver 2 includes an infrared receiver 9 that receives a radio signal from the infrared emitter 6 of the transmitter 1, a demodulation circuit 10 that demodulates a reception output signal of the infrared receiver 9, and a demodulation output of the demodulation circuit 10. An output switch circuit 11 interposed in a system for outputting a signal to an external audio device, a command detection circuit 12 for detecting an initialization command signal from a reception output signal of the infrared light receiving unit 9, and a reception output signal of the infrared light receiving unit 9 A reception level detection circuit 13 for detecting a level, a noise level detection circuit 14 for detecting a level of a noise component generated in a demodulated output signal of the demodulation circuit 10, a memory 15 for storing a squelch level, and a microcomputer 16 are provided. .

  Note that one or both of the demodulation circuit 10 and the noise level detection circuit 14 have a circuit configuration that is insensitive to the initialization command signal.

  The microcomputer 16 executes the control procedure shown in FIG. The microcomputer 16 constantly monitors the output of the command detection circuit 12 (step 301 in FIG. 3), and executes the normal mode in the normal use state where the initialization command signal is not detected. That is, the reception level detected by the reception level detection circuit 13 is always compared with the squelch level stored in the memory 15 (step 302), and the output switch circuit 11 is turned on while the reception level exceeds the squelch level. It is turned on (step 303), and the received and demodulated audio signal is output to an external audio device. On the other hand, when the reception level falls below the squelch level, the output switch circuit 11 is turned off (step 304) to prevent noise from being output to the outside.

  The microcomputer 16 executes the initialization mode when the command detection circuit 12 detects the initialization command signal. In the initialization mode, the output switch circuit 11 is turned off (step 310), and the output of the noise level detection circuit 14 is monitored in this state to determine whether or not the noise level exceeds a specified level (step 311). When a noise level exceeding the specified level is detected, the reception level detected by the reception level detection circuit 13 is compared with the squelch level stored in the memory 15 (step 312), and if the reception level is larger. The stored value of the memory 15 is left as it is, and if the reception level is smaller, the value of the reception level is updated and stored in the memory 15 (step 313). The above operation is repeated while the initialization command signal is detected.

=== How to use the initialization mode ===
A case where the wireless microphone transmission device 1 and the reception device 2 according to the present invention are attached to a karaoke device will be described. This karaoke apparatus is installed in a karaoke box together with a device such as a PDP to determine the layout. After that, the initialization switch of the wireless microphone transmission device 1 is pushed, and the transmission device 1 is operated in the initialization mode, and the transmission device 1 is gently moved away from the reception device 2 little by little or hidden in the shadow of the table or sofa. In other words, a situation is created in which the infrared wireless signal emitted from the transmission device 1 becomes difficult to reach the reception device 2 little by little.

 When the transmission device 1 is handled in this way, the following operation is performed in the reception device 2. It is detected that the infrared wireless signal received from the transmission apparatus 1 is modulated by the initialization command signal, and the initialization mode is executed (step 301 → 310). When the transmitter 1 is present near the receiver 2, the infrared wireless signal emitted from the transmitter 1 reaches the receiver 2 with sufficient strength, while the interference level from the PDP is relatively small. The noise level output from the demodulation circuit 10 is smaller than the reference value. Accordingly, the receiving apparatus 2 does not do anything and continues to detect the initialization command signal (step 311 → 301). As the intensity of the infrared radio signal that gradually reaches away from the receiving device 2 and reaches the receiving device 2 gradually decreases, the interference level becomes relatively large and the noise level output from the demodulation circuit 10 becomes large. When this noise level becomes higher than a predetermined reference level, the reception level of the infrared wireless signal at that time is compared with the stored value of the memory (step 311 → 312). If this is equal to or greater than the memory value, it is left as it is (step 312 → 301), and if it is smaller than the memory value, the memory is rewritten (step 313). The above processing is repeated during the initialization mode, and the minimum value of the reception level is stored in the memory. Accordingly, a squelch level that can reliably block the influence of stationary interference noise without setting the squelch operation excessively more than necessary is set.

=== Technical matters to be considered in implementation ===
When the initialization mode is activated, a predetermined default value is set in the memory. The default value is set to a value that allows the squelch operation to be sufficiently effective in a general environment. Then, by performing the initialization mode processing according to the present invention, a more appropriate squelch level is set so as not to apply the squelch operation more than necessary. Therefore, the default value may be rewritten only when the memory value set / updated when the initialization mode is activated last time is smaller than the default value.

 If the interference noise intensity slightly fluctuates around a certain level, the reception level in the most deteriorated state, that is, the maximum reception level when a specified noise level is detected is stored in the memory. (Yes / No operation is switched in step 312). Thereby, it is possible to set a squelch level capable of reliably blocking disturbing noise that slightly varies. In this case, contrary to the above embodiment, the memory is set to the minimum value when the initialization mode is activated.

 In the above-described embodiment, the initialization switch is an automatic return type push button switch, and the initialization mode is set only while the switch is being pressed. However, the present invention is not limited to this. Once the initialization switch is instructed to be turned on, the initialization command signal may be continuously sent for a predetermined time even if the hand is released. In addition, it is desirable to display a predetermined signal so that the operator can understand, such as lighting the initialization switch in a specific color while operating in the initialization mode.

 In order to prevent the general user from operating the switch unnecessarily, it must be placed in the cover, or it must not be pressed for a predetermined period of time, or it may not be activated, or a plurality of predetermined buttons may be pressed simultaneously or in sequence. It is desirable not to start unless operated.

 The squelch level stored in the memory may store the received signal level value as it is as the squelch level, or may store a value lower or higher by a predetermined width based on the received signal level value. .

  In addition, in the said Example, although it is related with an infrared type wireless microphone, it is not restricted to infrared rays. For example, the present invention can be applied even in a wireless microphone using an FM modulation type radio wave in an environment in which a certain level of noise radio wave is mixed.

It is a functional block diagram of the wireless microphone transmission apparatus and wireless microphone reception apparatus of a present Example. It is a processing flowchart in the wireless microphone transmission apparatus which concerns on a present Example. It is a process flow figure in the wireless microphone receiver which concerns on a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless microphone transmitter 2 Wireless microphone receiver 3 Acoustoelectric converter 4 Input switch circuit 5 Modulation circuit 6 Infrared light emitter (transmission circuit)
7 Initialization switch 8 Microcomputer (control means)
9 Infrared receiver (receiver circuit)
DESCRIPTION OF SYMBOLS 10 Demodulation circuit 11 Output switch circuit 12 Command detection circuit 13 Reception level detection circuit 14 Noise level detection circuit (noise level detection means)
15 memory 16 microcomputer (control means)

Claims (1)

A wireless microphone system specified by the following items (1) to (21).
(1) A wireless microphone system including a transmission device and a reception device. (2) The transmission device includes an acoustoelectric converter, an input switch circuit, a modulation circuit, a transmission circuit, an initialization switch, and a transmission. (3) The acoustoelectric converter receives an acoustic input and outputs an audio signal. (4) The input switch circuit turns on and off the input of the audio signal from the acoustoelectric converter to the modulation circuit. (5) The modulation circuit modulates and outputs the carrier signal with the audio signal from the acoustoelectric converter or the squelch level initialization command signal from the transmission control means. (6) The transmission circuit modulates the carrier signal. The output of the circuit is converted into a radio signal and transmitted. (7) The initialization switch can input an initialization command by the user's operation. (8) When the transmission control means performs the normal transmission mode. In addition, when there is an initialization command input by the initialization switch, the normal transmission mode is switched to the initialization command mode. (9) In the normal transmission mode, the input switch circuit is turned on and modulated by the audio signal. (10) In the initialization command mode, the input switch circuit is turned off, and the radio signal modulated by the initialization command signal is output from the transmission circuit. (11) A reception circuit, a demodulation circuit, an output switch circuit, a reception level detection circuit, a command detection circuit, a noise level detection circuit, a memory, and a reception control means. (12) The reception circuit outputs from the transmission circuit. (13) The demodulator circuit demodulates the output of the receiver circuit and outputs an audio signal (14) The output switch circuit demodulates (15) The reception level detection circuit detects the reception level of the reception circuit (16) The command detection circuit detects the initialization command signal from the output of the reception circuit (17 ) The noise level detection circuit detects the noise level of the output of the demodulation circuit. (18) The memory stores the squelch level. (19) The reception control means performs the normal reception mode, and the command detection circuit Switching from normal reception mode to initialization mode when an initialization command signal is detected (20) Normal reception mode is when the reception level detected by the reception level detection circuit exceeds the squelch level stored in the memory. Turn the output switch circuit on, otherwise turn it off (21) The initialization mode is a noise level detection circuit that detects noise. Store the squelch level corresponding to the reception level detected by the reception level detection circuit when the level is higher than the specified level.

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