JPH0531855B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a wireless microphone system used primarily for consumer use.

Background technology and its problems Wireless microphones for the general public use a normal FM receiver as a receiver, and the transmission output is very weak, so the service area is about 30 meters indoors.

On the other hand, for example, a wireless microphone is being considered that uses one channel out of 10 channels allocated to the 400 MHz band and has a transmission output of about 10 mW.

Such wireless microphones have a large transmission output and also have a dedicated receiver, so the service area is as wide as 100 meters or more.

However, with such a wide service area,
If other wireless microphones use the same channel or adjacent channels at a venue such as a wedding reception, interference will occur.

Therefore, in such a case, it is necessary to search for an empty channel and, when an empty channel is found, to set the transmitting channel of the wireless microphone and the receiving channel of the receiver to the empty channel. However, such operations are a burden for general users with little knowledge of electronic circuits, and if the channel is set incorrectly, the wireless microphone becomes unusable. Furthermore, if the switch for setting the channel is located in a place where it can be easily operated from the surface of the wireless microphone, the channel may be changed without realizing it, and as a result, the wireless microphone may become unusable. Furthermore, if the switch for setting the channel is located inside the wireless microphone, setting the channel is difficult, which is also a burden for general users.

Purpose of the Invention This invention attempts to solve these problems.

Summary of the Invention Therefore, in this invention, when the wireless microphone is set at a predetermined position of the receiver, the wireless microphone stops transmitting, and the receiver searches for an empty channel and sets the receiving channel to the empty channel. At the same time, data indicating the empty channel is sent to the wireless microphone, and the transmission channel of the wireless microphone is set to the empty channel.

Embodiment That is, in FIG. 1, 100 indicates a wireless microphone, and 117 is its transmitting antenna. Further, 200 indicates a receiver, and 201
211 is a receiving antenna, 218 is a speaker, and the receiving section 201 houses a receiving circuit, a control circuit, and the like. Furthermore, a recess 202 with a wide center is formed on, for example, the upper surface of the receiving section 201, and FIG. 1 shows a state in which the microphone 100 is set in this recess 202. Note that in this state, it is possible to send data indicating an empty channel from the receiver 200 to the microphone 100.

The circuits of the wireless microphone 100 and the receiver 200 are configured as shown in FIG. 2, for example. However, in this example, the channel is 100kHz from 400MHz to 400.9MHz.
Assume that there are 10 channels in steps.

That is, in the wireless microphone 100, the audio signal Sa from the microphone unit 111 is supplied to the FM modulation circuit 113 through the low frequency amplifier 112, and is converted to a signal with a carrier frequency of 10.7MHz.
This signal Si is used as the FM signal Si, and this signal Si is sent to the mixer circuit 11.
4, and the carrier frequency of signal Si is 10.7MHz, which is lower than the transmission frequency in VCO 121.
An oscillation signal So having a lower frequency is formed, and this signal So is supplied to the mixer circuit 114 to generate the signal Si
is frequency-converted to an FM signal Sf of a predetermined transmission channel, and this signal Sf is sent to a high-frequency power amplifier 115.
The signal Sf is further supplied to the transmitting antenna 117 through the tank circuit 116 whose passband is all channels, and the signal Sf is transmitted to the receiver 200.

In this case, VCO121 is PLL120
constitutes part of. That is, VCO121
The signal So from is supplied to the variable frequency divider circuit 122 and divided into a frequency of 1/N, and this frequency divided signal is supplied to the phase comparator circuit 123, and at the same time, the signal So from the reference oscillation circuit 124 is outputted from the reference oscillation circuit 124 as an oscillation signal with a frequency of 100kHz. is taken out and supplied to the comparison circuit 123, and the comparison output is passed through the low-pass filter 125 to the VCO1.
21 as its control voltage. Note that at this time, the value N of the frequency divider circuit 122 is
Supplied from.

Therefore, in a steady state, the frequency of the oscillation signal So is 100×N [kHz], so the value N is set to N=3893~
If you change it in one step within the range of 3902,
The carrier frequency of FM signal Sf is 400MHz ~
400.9MHz can be changed every 100kHz, therefore,
Transmission can be performed on any channel for each channel.

On the other hand, in the receiver 200, the transmitted signal is received by the Sf antenna 211, and is further supplied to the mixer circuit 214 through the antenna tuning circuit 212 whose passband is all channels and the high frequency amplifier 213, and the oscillation signal is sent to the VCO 221. So is formed, this signal So is supplied to the mixer circuit 214, and the signal Sf has an intermediate frequency.
Frequency converted to 10.7MHz intermediate frequency signal Si,
This signal Si passes through the intermediate frequency amplifier 215 to the FM
The audio signal Sa is supplied to a demodulation circuit 216 and demodulated, and this signal Sa is supplied to a speaker 218 through a low frequency amplifier 217.

In this case, the VCO 221, together with the variable frequency divider circuit 222, the phase comparison circuit 223, the reference oscillation circuit 224, and the low-pass filter 225,
It constitutes a PLL 220 similar to the PLL 120, and at this time, the value N of the frequency dividing circuit 222 is supplied from the microcomputer 230. Therefore, the value N of the frequency dividing circuit 222 is N=
Any channel can be received by changing in one step within the range of 3893 to 3902.

Further, in order to set the transmission/reception channel between the wireless microphone 100 and the receiver 200 to an empty channel, the following configuration is further provided.

That is, in the receiver 200, the output signal of the demodulation circuit 216 is supplied to a high-pass filter 241 whose passband is higher than that of the audio signal Sa, and the output of the filter is supplied to the detection circuit 242, which determines whether or not there is a filter output. is detected, and its detection output Sd is supplied to the microcomputer 230.

The receiver 200 is also provided with a normally open switch 243 that is driven by the microphone 100 when the wireless microphone 100 is set as shown in FIG. 1, and is also provided with a connector 244 that is connected to the microphone 100. ,
These switches 243 and connectors 244 are connected to the microcomputer 230. Also, 245,246
is an LED for display.

Furthermore, 250 is a power supply circuit having a power transformer, a rectifier circuit, etc., 251 is its power plug, and the DC voltage from this power supply circuit 250 is supplied to each part as an operating voltage, and the connector 2
44 is also supplied.

On the other hand, the wireless microphone 100 is provided with a connector 144 connected to the connector 244, which is connected to the latch 131.

Further, 150 is a rechargeable battery, for example, a nickel cadmium battery, and its voltage is supplied to the latch 131 as its operating voltage.
3, it is supplied to each part as its operating voltage. Note that the switch 143 is similar to the switch 243, and is a normally closed switch that is turned off when the wireless microphone 100 is set in the receiver 200.

Then, the following operations are performed by the processing of the microcomputer 230. That is, the wireless microphone 100 is connected to the receiver 20 as shown in FIG.
When set in the recess 202 of 0, the connector 144
and 244 are connected, and microphone 1
By setting 00, switch 143,2
43 is driven, switch 143 is turned from on to off, and switch 243 is turned from off to on.

Therefore, when the switch 143 is turned off, the wireless microphone 100 stops transmitting. Further, when the switch 243 is turned on, the value N is supplied from the microcomputer 230 to the frequency dividing circuit 222, and this value N is incremented by 1 in the range of N=3893 to 3902, so that the reception channel of the receiver 200 becomes 1. It changes channel by channel.

Then, when the reception channel reaches a certain value, if a wireless microphone is being used elsewhere, only the audio signal Sa is obtained from the demodulation circuit 216, and this is cut by the filter 241, so that the detection circuit 242 Detection output Sd is “0”
becomes. However, if the wireless microphone is not used elsewhere, limiter noise containing components outside the audio band is obtained from the demodulation circuit 216, and this passes through the filter 241, so the detection output
Sd becomes "1".

In this way, the reception channel is sequentially changed, and at this time, the microcomputer 230 checks the detection output Sd for "0" and "1" to search for an empty channel. Note that during this search period, the LED 245 blinks to indicate that a search for an empty channel is in progress. Furthermore, the LED 246 is off.

Then, for a certain reception channel (N=Ni
), when Sd = "1", this is an empty channel, so the value N of the frequency divider circuit 222 is fixed to the value Ni at this time, and this value Ni is transmitted from the microcomputer 230 in parallel to the connector 244, 14
4 into latch 131. Also,
The LED 245 goes out and the LED 246 lights up to indicate that it has been set to an empty channel.

Note that when all channels are in use, the LED 245 changes from blinking to lighting up. Also,
During the search, the DC voltage of the power supply circuit 250 is supplied to the battery 150 through the connectors 244, 144, and the battery 150 is charged.

Then, when the LED 246 lights up, when the wireless microphone 100 is taken up from the receiver 200, the switch 143 is turned on and the switch 243 is also turned off. Wireless microphone 100 can be used.

Thus, according to the present invention, when a wireless microphone is used, an empty channel is used, so that interference with other wireless microphones does not occur. Furthermore, in this case, simply placing the wireless microphone 100 at a predetermined position on the receiver 200 sets it to an empty channel, so even a general user with little knowledge of electronic circuits can easily and correctly use it. Also,
There is no need to be conscious of the channel, and there is no chance of accidentally changing the channel during use. Furthermore, since the wireless microphone 100 stops transmitting while searching for an empty channel, there is no waste in searching for an empty channel. Additionally, compared to general wireless microphones and receivers, there are fewer additional circuits, and therefore, there is less cost increase.

FIG. 3 shows another example of the receiver 200 and the wireless microphone 100.

That is, in the receiver 200 shown in FIG. 3, the intermediate frequency signal from the intermediate frequency amplifier 215 is supplied to the muting signal forming circuit 251 to generate the signal Sf.
A mutating signal Sm that is "1" when there is a signal and "0" when it is not present is formed, and this signal Sm is supplied to the amplifier 217 to perform muting. Further, this signal Sm is supplied to the inverter 252 to be used as a detection signal Sd of the signal Sf, and is supplied to the microcomputer 230.

Further, when the microphone 100 is set in the receiver 200, the transmitter coils 261, 263 are provided at positions close to the microphone 100, and the wireless microphone 100 has pickup coils 161, 163 at positions that are electromagnetically coupled to the coils 261, 263. will be provided. Further, the voltage of the battery 150 is
is supplied without passing through the switch 143.

Therefore, when the wireless microphone 100 is set in the receiver 200, the switch 143 is turned off and transmission stops, and the switch 243 is turned off.
is turned on, and the reception channels of the receiver 200 are sequentially changed. Then, in the channel in use, Sd="0", but if a certain channel (N=Ni) is an empty channel, at this time Sd="1", so the receiving channel is fixed to the channel.

Next, the data of the value Ni of this empty channel is serially taken out from the microcomputer 230 and supplied to the coil 261 through the amplifier 262, and the clock is output from the microcomputer 230 to the amplifier 2.
64 to the coil 263.

Therefore, the data and clock of the value Ni of the empty channel are obtained in the coils 161 and 163, which are supplied to the latch 131 through the shaping amplifiers 162 and 164, and the value Ni is latched in the latch 131.

Therefore, since the receiver 200 and the wireless microphone 100 are set to an empty channel, the wireless microphone 100 can be used from now on.

In the example of FIG. 2, when the frequency divider circuit 122 has a latch function of the value N, the latch 131
can be omitted. Also, when sending the value N to the latch 131, instead of sending the value N, that is, the values 3893 to 3902, for example, the difference 0 to 9 with the value 3893 is sent, and the latch 131 adds it to the value 3893 to obtain the value N. If so, the number of bits when transmitting the value N can be reduced. Furthermore, the signal So is multiplied by the modulation circuit 11.
It may also be a carrier signal of 3.

Also, instead of turning off the power and stopping transmission using the switch 143, for example, the modulation circuit 113
The transmission may be stopped by turning off the operation. Further, when the wireless microphone 100 has a main power switch, it is possible to prevent transmission from occurring unless the wireless microphone 100 is set in the receiver 200 once the power switch is turned off.

Effects of the invention Interference with other wireless microphones can be avoided. Moreover, for this purpose, the user does not need any special knowledge or adjustment.
And it's also low cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view for explaining this invention, and FIGS. 2 and 3 are system diagrams of an example of this invention. 100 is a wireless microphone, 200 is a receiver, 120, 220 is a PLL, 144, 244
is a connector.

Claims (1)

[Claims] 1. Consisting of a wireless microphone that selects one channel from a plurality of channels and transmits, and a receiver that selects one channel from the plurality of channels and receives a signal from the wireless microphone, When the wireless microphone is set at a predetermined position of the receiver, the wireless microphone stops transmitting, and the receiver searches for an empty channel among the plurality of channels and sets the reception channel to the empty channel. and transmitting data indicating the empty channel to the wireless microphone through a contact or electromagnetic coupling means between the receiver and the wireless microphone to set the transmission channel of the wireless microphone to the empty channel. wireless microphone system.