JP7189924B2 - wireless microphone - Google Patents

Description

The present invention relates to wireless microphones.

Wireless microphones have multiple transmission channels with different frequencies. Prior to transmitting the audio signal, the transmission frequency is set by operating the frequency setting switch provided on the wireless microphone. When transmitting an audio signal, a PLL circuit provided in the wireless microphone converts the input audio signal into a transmission signal based on the set transmission frequency. That is, the wireless microphone is provided with a transmission frequency signal output unit that outputs a signal containing information on the set transmission frequency. converts the audio signal into a transmitted signal based on

Some wireless microphones are known to transmit control signals for controlling various devices provided on the receiver side in addition to audio signals. For example, a wireless microphone used on the premises of a train station can transmit several types of control signals to a receiver in response to operation of a control switch such as a button provided on the wireless microphone. Examples of control contents include transmitting to the receiver side that voice is being transmitted and broadcasting that voice from a speaker, etc., specifying the broadcast target range (track 1, track 2, etc.), ringing the departure bell, and confirming. signal transmission, etc. Such a control signal is also converted into a transmission signal through the PLL circuit, like the audio signal.

Furthermore, the aspects of technology for transmitting such a control signal from a wireless microphone to a receiver can be broadly classified into an analog tone control method and a digital control method, and some wireless microphones are known to allow selection of both methods. there is

WO2013/136766

In the conventional wireless microphone, the following processing is executed from when the power switch is turned on until the audio signal is transmitted. When the power switch is turned on and the initialization of the CPU circuit, which is the controller of the wireless microphone, is completed, the CPU circuit first reads the transmission frequency value preset by the frequency setting switch. When the set transmission frequency value is read, the frequency signal output unit outputs the transmission frequency of the read value to the PLL circuit. When a predetermined lockup time elapses after the transmission frequency is input, the PLL circuit is locked based on this transmission frequency and a carrier wave is generated. This carrier wave is modulated by an audio signal and transmitted through a buffer amplifier and an antenna section.

As described above, the CPU circuit is initialized, the set transmission frequency value is read, the transmission frequency is output by the frequency output section, the PLL is Each process takes time, such as circuit lockup time. Therefore, if the user inputs voice immediately after turning on the power switch, the PLL circuit may not be locked in time and the first part of the voice may be interrupted.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wireless microphone which shortens the time until the PLL circuit is locked, thereby preventing the audio from being interrupted.

A wireless microphone according to the present invention has the following configuration.
(1) A PLL circuit that generates a carrier wave, modulates the carrier wave with an audio signal input from a microphone amplifier, and outputs the carrier wave as a transmission signal to the antenna section.
(2) an oscillator that outputs a reference signal to the PLL circuit;
(3) A frequency setting switch for presetting the transmission frequency.
(4) A frequency signal output section for outputting a temporary frequency signal and a transmission frequency signal of the transmission frequency set by the frequency setting switch to the PLL circuit.
(5) A power switch that supplies power to the wireless microphone.
(6) When the power switch is turned on, the frequency signal output unit outputs a temporary frequency signal, starts reading the transmission frequency set by the frequency setting switch, and transmits the read transmission frequency. A frequency signal is output to the PLL circuit instead of the temporary frequency signal.

Moreover, the wireless microphone of the present invention may further include the following configuration.
(1) It further includes a switch that prevents the transmission signal from being output to the antenna section until the PLL circuit is locked.
(2) A buffer amplifier that is ON/OFF controlled by the switch is provided on the output side of the PLL circuit, and the PLL circuit is provided with a lock notification unit that detects the locked state and outputs a lock notification signal. The switch turns on the buffer amplifier based on the lock notification signal from the lock notification unit.
(3) further comprising a control signal output unit for outputting a control signal for controlling various devices provided on the receiver side to the PLL circuit, wherein the PLL circuit receives the control signal from the control signal output unit; modulating the carrier;
(4) The control signal output unit includes an analog control signal output unit that outputs an analog control signal and a digital control signal output unit that outputs a digital control signal, and the control signal is the analog control signal or a digital control signal. It is one of the control signals.
(5) further comprising: an analog signal suppression switch provided between the microphone amplifier and the PLL circuit; and a suppression signal output section for controlling the analog signal suppression switch, wherein the suppression signal output section receives the control signal. is the digital control signal, the analog signal suppression switch is turned off for a predetermined time.

INDUSTRIAL APPLICABILITY The present invention can provide a wireless microphone that reduces the time required to lock the PLL circuit and prevents audio from being interrupted.

1 is a block diagram showing the configuration of a wireless microphone according to an embodiment; FIG. 4 is a flow chart showing the operation of the wireless microphone according to the embodiment;

[First Embodiment]
[Constitution]
(Schematic configuration of the main part)
As shown in FIG. 1 , the wireless microphone 100 of this embodiment includes a microphone amplifier 1 , a PLL circuit 2 , an oscillator 3 , a buffer amplifier 41 , an antenna section 5 and a control section 6 . Also, the wireless microphone 100 has a power switch 91 for supplying power to the wireless microphone 100, a frequency setting switch 92 for channel setting, a control switch 93 for transmitting control signals, and a control signal type selection. and an operation setting switch 94 for performing the operation.

(microphone amplifier)
A microphone amplifier 1 amplifies an audio signal input from a user and outputs the amplified audio signal to a PLL circuit 2 provided in the subsequent stage.

(PLL circuit)
The PLL circuit 2 includes a voltage controlled oscillator 21 , a variable frequency divider 22 , a phase comparator 23 , a loop filter 24 and a lock notification section 25 .

The voltage controlled oscillator 21 generates a carrier wave, modulates this carrier wave with an audio signal, and outputs it as a transmission signal. More specifically, the voltage-controlled oscillator 21 generates a carrier wave with an oscillation frequency controlled based on the signal input from the loop filter 24, modulates the carrier wave with the audio signal input from the microphone amplifier 1, and transmits it. output as a signal.

The variable frequency divider 22 is provided after the voltage controlled oscillator 21 and divides the frequency of the transmission signal by changing the frequency division ratio. Thereby, the variable frequency divider 22 changes the frequency of the transmission signal based on the frequency signal output from the control section 6 . The phase comparator 23 is provided after the variable frequency divider 22, detects the phase difference between the frequency-divided transmission signal and the reference signal output from the oscillator 3, and generates a phase error signal. The phase comparator 23 outputs the phase error signal to the loop filter 24 provided in the subsequent stage. The loop filter 24 is, for example, a low-pass filter, which removes AC components from the phase error signal and smoothes it. This smoothed signal is input to the voltage controlled oscillator 21 together with the audio signal from the microphone amplifier 1 .

As described above, the PLL circuit 2 controls the oscillation frequency of the voltage controlled oscillator 21 based on the signal input from the loop filter 24 . Further, when the oscillation frequency of the voltage controlled oscillator 21 reaches a steady state (locked state), the lock notification unit 25 outputs a lock notification signal to the control unit 6 .

(buffer amplifier)
The buffer amplifier 41 amplifies the transmission signal output from the voltage-controlled oscillator 21 and transmits it from the antenna section 5 provided in the subsequent stage. A buffer switch 42 is provided in the buffer amplifier 41 , and ON/OFF of the buffer amplifier 41 is switched by the buffer switch 42 . That is, only when the buffer amplifier 41 is ON, it amplifies the transmission signal and outputs it to the antenna section 5 provided in the subsequent stage. This ON/OFF switching is performed by a buffer amplifier ON/OFF signal output from the control unit 6 to the buffer switch 42 . It should be noted that the buffer amplifier 41 of this embodiment is turned off by default, and is turned on only by a buffer amplifier ON/OFF signal.

(control part)
The control unit 6 is composed of a CPU circuit and a storage, and controls each configuration described above. Therefore, the control unit 6 includes a frequency signal output unit 61 that outputs a temporary frequency signal and a transmission frequency signal to the PLL circuit 2, a buffer amplifier ON/OFF signal output unit 62 that controls the buffer switch 42, and an analog control signal output unit. 63, a digital control signal output unit 64, an inhibition signal output unit 65 for inhibiting input of the audio signal and the analog control signal to the PLL circuit 2, and a storage unit 66 for storing various data.

The frequency signal output unit 61 outputs the temporary frequency signal and the transmission frequency signal including the information of the transmission frequency value set by the frequency setting switch 92 to the variable frequency divider 22 at different timings. The temporary frequency signal is output immediately after initialization of the CPU circuit constituting the control unit 6 is completed by operating the power switch 91 provided in the wireless microphone 100, and has a value different from that of the transmission frequency signal. It is a signal containing frequency information. On the other hand, the transmission frequency signal is set in advance by the frequency setting switch 92 and contains information on the transmission frequency stored in the storage unit 66. After the completion of the initialization of the CPU circuit, the frequency signal output unit 61 outputs that value. is read out from the storage unit 66 to be output to the variable frequency divider 22 of the PLL circuit 2 . Further, the frequency signal output unit 61 suspends the output of the provisional frequency signal when outputting the transmission frequency signal.

The buffer amplifier ON/OFF signal output unit 62 outputs a buffer amplifier ON/OFF signal to the buffer switch 42 when a lock notification signal indicating that the PLL circuit 2 has reached a steady state is input from the lock notification unit 25 . .

The analog control signal output unit 63 outputs an analog control signal to the voltage controlled oscillator 21 via a low-pass filter 71 that removes high frequency components and an analog signal suppression switch 8 that will be described later. The digital control signal output unit 64 outputs the digital control signal to the voltage controlled oscillator 21 through the low-pass filter 72 that removes high frequency components.

When the digital control signal output unit 64 outputs the digital control signal, the suppression signal output unit 65 outputs the suppression signal to the analog signal suppression switch 8 to turn off the analog signal suppression switch 8 for a predetermined time. This blocks the audio signal when using a digital control signal. Thus, the analog signal suppression switch 8 switches between using at least one of the audio signal and the analog control signal and using the digital control signal as the modulation signal input to the voltage controlled oscillator 21 . Note that the analog signal suppression switch 8 of the present embodiment is in the ON state by default.

The storage unit 66 is configured by a storage, and stores various programs for operating the control unit 6, the frequency set for the transmission frequency signal, the analog control signal or the digital control signal to be selected, the control content, etc. It stores the information necessary for the operation of 6.

(switch)
The control switch 93 instructs the analog control signal output section 63 or the digital control signal output section 64 to output an analog control signal or a digital control signal. The operation setting switch 94 sets whether to use an analog control signal or a digital control signal as the control signal. This sets which of the analog control signal output section 63 and the digital control signal output section 64 is operated.

The operation setting switch 94 can also set the contents of these control signals. The content of the control signal is, for example, to switch the output destination of the audio signal from the speaker provided at the platform of the station to the speaker provided at the station office or emergency contacts. As a result, the output destination of the audio signal can be changed before and after the control signal is output. In addition, the control signal can be used to output to various devices provided on the receiver side a signal to close the platform door of the station, the ringing of the departure bell, and the like. Since these settings are stored in the storage section 66, the analog control signal output section 63, the digital control signal output section 64, and the suppression signal output section 65 operate with reference to the storage section 66. FIG.

The power switch 91, the frequency setting switch 92, the control switch 93, and the operation setting switch 94 are composed of slide switches, rotary switches, push buttons, touch panels, and the like for user operation.

[Action]
(1) Transmission of Audio Signal The operation of the wireless microphone 100 according to this embodiment will be described with reference to FIG. It is assumed that the frequency of the transmission frequency signal is set by the frequency setting switch 92 and whether to use the analog control signal or the digital control signal is set by the operation setting switch 94 according to the usage situation. It is also assumed that when the power switch of the wireless microphone 100 is turned on, the buffer amplifier 41 is turned off and the analog signal suppression switch 8 is turned on.

When the power switch of wireless microphone 100 is turned on, the CPU circuit forming controller 6 is initialized (step S01). However, the information stored in the storage unit 66 is not initialized. When the initialization of the CPU circuit is completed, the frequency signal output unit 61 outputs a temporary frequency signal to the variable frequency divider 22 and starts reading the transmission frequency set by the frequency setting switch 92 (step S02).

Next, the operation of the PLL circuit 2 will be explained. The output signal of the voltage controlled oscillator 21 is frequency-divided by the variable frequency divider 22 based on the frequency set as the temporary frequency signal, and is input to the phase comparator 23 . In the phase comparator 23, the frequency-divided output signal is compared with the reference signal input from the oscillator 3, and a phase error signal is output from the phase difference between the two signals. This phase error signal has its AC component removed through the loop filter 24 and is input to the voltage controlled oscillator 21 . As a result, the PLL circuit 2 starts operating at the frequency set as the temporary frequency signal (step S03). That is, the oscillation frequency of the voltage controlled oscillator 21 starts following the frequency value included in the provisional frequency signal.

In parallel with the operation of the PLL circuit 2 as described above, when the reading of the transmission frequency by the frequency signal output section 61 is completed, the frequency signal output section 61 interrupts the output of the provisional frequency signal and instead reads this read frequency signal. A transmission frequency signal containing information on the transmission frequency is output to the variable frequency divider 22 . As a result, the voltage controlled oscillator 21 is locked at the transmission frequency and generates a carrier wave of the transmission frequency (step S04). This carrier wave is modulated by the audio signal input from the microphone amplifier 1, becomes a transmission signal, and is output from the PLL circuit 2 (step S05).

In response to the fact that the PLL circuit 2 is locked, the lock notification unit 25 outputs a lock notification signal to the buffer amplifier ON/OFF signal output unit 62 . The buffer amplifier ON/OFF signal output unit 62 to which the lock notification signal is input outputs the buffer amplifier ON/OFF signal to the buffer switch 42, and the buffer switch 42 receives this and turns on the buffer amplifier 41 (step S06). As a result, the transmission signal is amplified by the buffer amplifier 41 and transmitted from the antenna section 5 (step S07).

(2) Transmission of Control Signals Next, modulation of carrier waves by control signals will be described. Description of steps S01 to S04, S06, and S07 will be omitted since they correspond to step S05 described above. After the power switch of wireless microphone 100 is turned on, by operating control switch 93, analog control signal output section 63 or digital control signal output section 64 outputs an analog control signal or a digital control signal. Which control signal is output depends on the setting of the operation setting switch 94. First, let us consider the case where the analog control signal is set. The analog control signal is output to the analog signal suppression switch 8 via the low-pass filter 71 . In this case, since the analog signal suppression switch 8 is not controlled and remains ON, the signal is output to the voltage controlled oscillator 21 as it is. A carrier wave generated by the voltage controlled oscillator 21 is modulated by this analog control signal, and the modulated carrier wave is transmitted from the antenna section 5 as a transmission signal.

A case where a digital control signal is set to the operation setting switch 94 will be described. The digital control signal is output to voltage controlled oscillator 21 via low pass filter 72 . In this case, the suppression signal output unit 65 outputs the suppression signal to the analog signal suppression switch 8 to turn off the analog signal suppression switch 8 for a predetermined time. As a result, since the analog signal suppression switch 8 is in the OFF state, the audio signal is not output to the voltage controlled oscillator 21 even if the audio signal is input from the microphone amplifier 1 at the same time as the digital control signal. Since the analog signal suppression switch 8 returns to the ON state after a predetermined time, the audio signal from the microphone amplifier 1 is also output to the voltage controlled oscillator 21 thereafter. A carrier wave generated by the voltage controlled oscillator 21 is modulated by this digital control signal, and the modulated carrier wave is transmitted from the antenna section 5 as a transmission signal.

[effect]
(1) The wireless microphone 100 of the present embodiment outputs a temporary frequency signal to the PLL circuit 2 immediately after power is supplied by the power switch 91, and starts reading the transmission frequency to be used. Upon receiving the provisional frequency signal, the PLL circuit 2 starts operating. When the reading of the transmission frequency is completed, the output of the temporary frequency signal is interrupted, and instead the transmission frequency signal containing the information of the transmission frequency whose reading is completed is output to the PLL circuit 2 . This transmission frequency signal brings the PLL circuit 2 into a locked state. In this embodiment, the lockup time of the PLL circuit 2 is shortened because the PLL circuit 2 is operated by the provisional frequency signal before the transmission frequency signal is read.

(2) In the wireless microphone 100 of the present embodiment, the buffer amplifier 41 is in the OFF state until the PLL circuit 2 is locked, so there is no risk of transmitting radio waves at the frequency set as the temporary frequency signal. .

(3) The wireless microphone 100 of this embodiment includes an analog control signal output section 63 and a digital control signal output section 64 . The analog control signal output section 63 outputs an analog control signal, and the digital control signal output section 64 outputs a digital control signal. As a result, when it is desired to control various devices provided on the receiver side by means of control signals, it is possible to control these devices even if they support only one of analog control signals and digital control signals. I can.

(4) The wireless microphone 100 of the present embodiment includes the analog signal suppression switch 8, and when outputting the digital control signal, the suppression signal output unit 65 turns off the analog signal suppression switch 8 to output the audio signal. can be blocked. This eliminates the possibility that the audio signal, which is an analog signal, and the digital control signal, which is a digital signal, are output to the PLL circuit 2 at the same time.

[Other embodiments]
The present invention is not limited to the above-described embodiments, and can be embodied by modifying constituent elements without departing from the scope of the present invention at the implementation stage. Further, various inventions can be formed by appropriate combinations of the plurality of constituent elements disclosed in the above embodiments. For example, some components may be omitted from all components shown in the embodiments. Specifically, the following other embodiments are also included.

(1) The control unit 6 of the above embodiment includes the analog control signal output unit 63, the digital control signal output unit 64, and the suppression signal output unit 65, but these configurations may be omitted.

(2) The control unit 6 in the above embodiment includes the analog control signal output unit 63 and the digital control signal output unit 64, but the number of control signal output units may be one. If the control signal output section outputs only an analog control signal, the analog signal suppression switch 8 may be omitted because the carrier wave can be modulated simultaneously with the audio signal, which is the same analog signal.

(3) In the above embodiment, the buffer amplifier 41 and the buffer switch 42 for switching ON/OFF of the buffer amplifier 41 are provided. As a result, the buffer amplifier can be responsible for amplifying the transmission signal, and the switch can be responsible for output control of the transmission signal.

(4) The buffer switch 42 in the above embodiment is controlled by the lock notification signal from the lock notification unit 25 via the buffer amplifier ON/OFF signal output unit 62, but the present invention is not limited to this. For example, the lockup time of the PLL circuit 2 may be measured in advance, and the buffer amplifier ON/OFF signal output unit 62 may output the buffer amplifier ON/OFF signal at the same time as this time elapses. That is, the buffer switch 42 may be ON/OFF controlled based on the elapsed time instead of based on the lock notification signal. In this case, even if the control to turn off the buffer amplifier 41 is performed again when the PLL circuit 2 is unlocked for some reason, there is no possibility that the communication will be interrupted. Also, when the PLL circuit 2 is locked at the temporary frequency, there is no possibility that the audio signal will be transmitted at the temporary frequency. Therefore, since the transmission signal generated based on the temporary frequency signal is not finally output from the buffer amplifier 41 to the antenna unit 5, the frequency set as the temporary frequency signal is a frequency not used by the wireless microphone 100. It may be of a band.

(5) Two frequency setting switches 92 in the above embodiment may be provided. For example, one may be composed of a rotary switch and the other may be composed of a slide switch. The frequency setting switch 92, which is a slide switch, is particularly suitable for the present invention because it can be quickly operated by the user.

Reference Signs List 100 Wireless microphone 1 Microphone amplifier 2 PLL circuit 21 Voltage controlled oscillator 22 Variable frequency divider 23 Phase comparator 24 Loop filter 25 Lock notification unit 3 Oscillator 41 Buffer amplifier 42 Buffer switch 5 Antenna section 6 Control section 61 Frequency signal output section 62 Buffer amplifier ON/OFF signal output section 63 Analog control signal output section 64 Digital control signal output section 65 Suppression signal output section 66 Storage sections 71 and 72 Low-pass filter 8 Analog signal suppression switch 91 Power switch 92 Frequency setting switch 93 Control switch 94 Operation setting switch

Claims (6)

a PLL circuit that generates a carrier wave, modulates the carrier wave with an audio signal input from a microphone amplifier, and outputs the carrier wave to an antenna unit as a transmission signal;
an oscillator that outputs a reference signal to the PLL circuit;
a frequency setting switch for presetting a transmission frequency;
a frequency signal output unit that outputs a temporary frequency signal and a transmission frequency signal having a transmission frequency set by the frequency setting switch to the PLL circuit;
a power switch that supplies power to the wireless microphone;
with
The frequency signal output unit is
When the power switch is turned on, outputting a temporary frequency signal and starting to read the transmission frequency set by the frequency setting switch,
outputting a transmission frequency signal of the read transmission frequency to the PLL circuit instead of the temporary frequency signal;
wireless microphone. further comprising a switch that does not output the transmission signal to the antenna unit until the PLL circuit is locked;
The wireless microphone of Claim 1. A buffer amplifier that is ON/OFF controlled by the switch is provided on the output side of the PLL circuit,
The PLL circuit is provided with a lock notification unit that detects the locked state and outputs a lock notification signal,
the switch turns on the buffer amplifier based on a lock notification signal from the lock notification unit;
A wireless microphone according to claim 2. further comprising a control signal output unit that outputs a control signal for controlling various devices provided on the receiver side to the PLL circuit,
The PLL circuit modulates the carrier wave with the control signal input from the control signal output unit.
A wireless microphone according to any one of claims 1 to 3. The control signal output unit is
an analog control signal output unit that outputs an analog control signal;
a digital control signal output unit that outputs a digital control signal;
with
said control signal is one of said analog control signal or a digital control signal;
A wireless microphone according to claim 4. an analog signal suppression switch provided between the microphone amplifier and the PLL circuit;
a suppression signal output unit that controls the analog signal suppression switch;
further comprising
The inhibition signal output unit turns off the analog signal inhibition switch for a predetermined time when the control signal is the digital control signal.
A wireless microphone according to claim 5.

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