JPH06132834A - Wireless audio equipment and receiver therefor - Google Patents

Abstract

PURPOSE:To transmit a lot of information signals with simple configuration in an audio equipment for transmitting audio signals to the receiver by radio. CONSTITUTION:An audio equipment 1 for transmitting audio signals L and R by radio is defined as an object. A modulation circuit 102 is provided to modulate the amplitude of a clock signal SCK from a microcomputer 40 for system control corresponding to information signals DMD related to the audio signals L and R. Then, an adder circuit 22L is provided to form a frequency multiplexed signal (L+SMD) by adding a modulated signal SMD from this modulation circuit 102 to the audio signal L. Further, a transmission circuit 20 is provided to transmit the frequency multiplexed signal (L+SMD) from this adder circuit 22L.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to audio equipment such as so-called headphone stereo.

[0002]

2. Description of the Related Art As a headphone type stereo cassette player (hereinafter simply referred to as "player") such as a Walkman (registered trademark), a wireless system between the player and the headphone is considered.

FIG. 7 is a perspective view showing the appearance of an example of the wireless cassette player, 1 is a player and 6 is a dedicated receiver for the headphones.

Then, in the player 1, during reproduction, the stereo audio signals L and R of the left and right channels are reproduced from the tape cassette (not shown), and the signals L and R are reproduced.
R is converted into FM signals SL and SR having predetermined frequency intervals, and these signals SL and SR are transmitted to the receiver 6.

Then, in the receiver 6, the player 1
When the FM signals SL, SR from the
Audio signals L and R are demodulated from L and SR, and these signals L and
R is supplied to the left and right acoustic units 7L and 7R of the headphone 7, respectively.

Furthermore, the receiver 6 is provided with a remote control function, and when the operation key 82 provided on the receiver 6 is operated, the player 1 is remote-controlled by this, and the player 1
Is remote controlled to play mode, stop mode, fast-forward mode, rewind mode, etc.

In this case, the receiver 6 can be half the size of a business card or smaller. Also, the distance that the receiver 6 can be used away from the player 1 is set to about 1.5 m in consideration of the Radio Law and the case where a nearby person uses a similar wireless player.

Therefore, according to this wireless type player, for example, when listening to a cassette on a commuter train, the player 1 is put in a bag, a bag or the like, and the receiver 6 is put in a chest pocket of a jacket. , The clip can be attached to a tie or the like by using the clip, and the cord of the headphone 7 does not get in the way.

However, when the player 1, the receiver 6 and the headphones 7 are separated from each other as described above,
When the player 1 is used in a bag or bag, the user cannot see the current operating state of the player 1 even if the player 1 is provided with an LED or LCD for displaying the current operating mode. .

Therefore, various troubles may occur when the player 1 is used. For example, when trying to listen to music that is recorded away from the current tape position,
The tape may be run in the opposite direction at high speed by mistaken key operation.

Alternatively, when the tape is at the beginning or the end of the tape, if the stop mode is changed to the reproduction mode,
Because of the leader tape, a silent period of at least about 5 seconds continues, which is difficult to distinguish from the silence in the stop mode. Therefore, the silent period may be mistaken for the fact that the player 1 could not be remote-controlled in the reproduction mode. Also, when auto-reversing from side A to side B, it is a leader tape, so 10
There is a silent period of more than a second, but when the cassette is played to the end of the A side, whether the auto reverse operates and the B side is started to play, or whether the auto reverse does not work and the stop mode is entered. It is difficult to distinguish.

Therefore, there has been considered a wireless player in which the operating state of the player 1 and the like can be known by the receiver 6.

8 and 9 show an example of such a player 1 and receiver 6. That is, in the player 1, 2 is a cassette magnetic tape, 10 is a reproducing circuit, and 20 is a reproducing circuit.
Is a transmission circuit, 30 is a tape running control means, and 40 is a microcomputer for system control.

In the tape running control means 30, 31 is a capstan, 32 is a capstan motor,
33 is a pinch roller, 34 is a capstan servo circuit,
Reference numeral 35 is a control mechanism.
The mechanical force of the player 1 is controlled to a stop mode, a reproduction mode, a forward direction mode, a backward direction mode, etc. by utilizing the rotational force of 3.

Further, in the player 1, 40 is a microcomputer for system control, 41 is an operation key such as a reproduction key and a stop key, and 50 is a receiving circuit of a remote controller.

When the reproduction key of the operation keys 41 is pressed, the microcomputer 40 controls the servo circuit 34 and the control mechanism 35 to set the player 1 in the reproduction mode, and the capstan 31 and the pinch roller 32 cause the tape 2 to move. Can be run at a constant speed. In this reproducing mode, the reproducing heads 11L and 11R reproduce the left and right channel audio signals L and R from the tape 2, and the signals L and R are reproduced equalizer amplifiers 12L and 12R.
→ pre-emphasis circuit 21L, 21R → adder circuit 22
FM modulation circuit 23L through L and 22R signal lines,
23R and converted into FM signals SLO and SRO.

In this case, the frequency deviation of the FM signals SLO and SRO is set to 75 kHz at a modulation factor of 100%, and the carrier frequencies fLO and fRO of the FM signals SLO and SRO are set.
Is set to be considerably lower than the transmission frequencies (carrier frequencies) fL and fR of the actual transmission signals SL and SR, for example, fLO = 11.29 MHz fRO = 11.75 MHz.

The FM signals SLO and SRO are supplied to the mixer circuits 24L and 24R, and the local oscillation circuit 25 supplies the local oscillation signal S25 for beatup to the mixer circuits 24L and 24R. The signal S25
The frequency f25 of is, for example, f25 = 64.00 MHz.

Thus, the signals SLO and SRO are frequency-converted by the signal S25 in the mixer circuits 24L and 24R so that the carrier frequencies fL and fR are fL = fLO + f25 = 75.29 MHz fR = fRO + f25 = 75.75 MHz FM signals SL and SR. To be done.

The FM signals SL and SR are converted into bandpass filters 26L and 26R and a power amplifier 27.
It is supplied to the antenna 28 through L and 27R, and the receiver 6
Sent to.

On the other hand, in the receiver 6, reference numeral 60 represents a receiving circuit. Then, the FM transmitted from the player 1
The signals SL and SR are received by the antenna 61, and the signals SL and SR are supplied to the mixer circuit 64 through the antenna tuning circuit 62 and the high frequency amplifier 63.
The local oscillation signal S is sent from the local oscillation circuit 65 to the mixer circuit 64.
65 is supplied. In this case, the frequency f65 of the signal S65 is
For example, f65 = 65.05 MHz.

In this way, the FM signals SL and SR are supplied to the mixer circuit 64 by the signal S65 so that the frequencies fLI and fRI can be obtained.
Is converted into intermediate frequency signals SLI and SRI of fLI = fL-f65 = 10.24 MHz fRI = fR + f65 = 10.70 MHz.

The signals SLI and SRI are supplied to the FM demodulation circuits 68L and 68R through the intermediate frequency filters 66L and 66R and the amplifiers 67L and 67R to demodulate the audio signals L and R, and the signals L and R are demodulated. Emphasis circuits 69L and 69R and output amplifiers 71L and 71
It is supplied to the acoustic units 7L and 7R of the headphone 7 through R respectively.

When the player 1 is set to an operation mode other than the reproduction mode, the audio signals L and R are not reproduced from the tape 2. However, even in such an operation mode, the FM signals SL and SR are transmitted. , The transmission is not performed only when the power switch (not shown) is turned off.

Further, since the player 1 is remote-controlled from the receiver 6, it is constructed as follows. That is, the receiver 6 includes a microcomputer 80 and a transmission circuit 90.
And the operation key 81 similar to the operation key 41 is connected to the microcomputer 80.

When the operation key 81 is operated, the data corresponding to the operated key is output from the microcomputer 80, this data is supplied to the transmission circuit 90 and becomes the FM signal S90, and this signal S90 is the antenna 91. Is transmitted to the player 1. In this case, the carrier frequency f90 of the FM signal S90 is, for example, f90 = 222.30 MHz.

On the other hand, the player 1 is provided with a receiving circuit 50, and the FM signal S90 from the receiver 6 is received by the antenna 51 and supplied to the receiving circuit 50, and the receiving circuit 50 is received.
The data corresponding to the operated key among the keys 41 of the receiver 6 is taken out from the
Supplied to zero.

In this way, when the key 81 of the receiver 6 is operated, the processing corresponding to the key operation is executed in the microcomputer 40, and the player 1 enters the operation mode corresponding to the operated key.

At this time, in order to display the operation mode of the player 1 on the receiver 6, the following structure is further provided. That is, the player 1 has the oscillation circuit 4
5, 46 and a switch circuit 47 are provided, and the frequency signals outside the audible band, for example, the frequencies f45 and f46, and the mode signals S45 and S46 of f45 = 10 Hz and f46 = 30 kHz are extracted from the oscillation circuits 45 and 46. .

The signals S45 and S46 are supplied to the adder circuits 22L and 22R through the switch circuit 47,
It is added to each of the audio signals L and R. However,
In this case, the switch circuit 47 is controlled by the microcomputer 40 according to the operation mode of the player 1, and the signal S4
5, S46 is for player 1 with respect to audio signals L and R
The combination is added, for example, as shown in FIG.

For example, when the tape 2 is reproduced in the forward direction (forward reproduction mode), the signal S45 is added to the signal L (marked with a circle), and the signal S46 is added to both the signals L and R. Not done (marked with x). Alternatively, when the tape 2 is fast-forwarded in the reverse direction (reverse-direction fast-forward mode), the signal S
45 is added to the signal R and signal S46 is added to the signal L.

Thus, the signals S45 and S46 are transmitted to the receiver 6 together with the audio signals L and R by the FM signals SL and SR.

Then, in the receiver 6, the demodulation circuit 6
The 8 L output signal is supplied to the detection circuit 85 including a low-pass filter, a high-pass filter, a detection circuit, and the like,
A detection signal S85 indicating whether the signal S45 or S46 is added to the signal L is taken out, and this signal S85 is supplied to the microcomputer 80. Similarly, the demodulation circuit 68
The output signal of R is supplied to the detection circuit 86, the detection signal S86 indicating whether the signal S45 or S46 is added to the signal R is taken out, and this signal S86 is output from the microcomputer 80.
Is supplied to.

Then, in the microcomputer 80, the signal L,
The operation mode of the player 1 is detected from the combination of the signals S45 and S46 added to R, the display data corresponding to the operation mode is supplied to the LCD 82, and the LCD 82 is displayed.
Indicates the operation mode of the player 1.

For example, when the signal S45 is added to the signal L and the signals S45 and S46 are not added to the signal R, FIG.
According to the above, since the tape 2 is being reproduced in the forward direction, a symbol indicating the "forward reproduction mode" is displayed on the LCD 82.

Therefore, according to the player 1 and the receiver 6 described above, for example, even when the player 1 is put in a bag or a bag and used, the current operation mode of the player 1 is determined by the LED 82 of the receiver 6. It is possible to prevent accidentally moving the tape in the opposite direction at high speed when trying to listen to music recorded at a position away from the current tape position. it can.

Alternatively, since it is possible to distinguish the state in which the leader tape at the beginning or the end of the tape is being reproduced from the stop mode, it is possible to set the player 1 to the reproduction mode with respect to the silence when the leader tape is reproduced. There is no mistake that I could not use the remote control. Further, at the time of auto-reverse, even if there is no sound, it is possible to distinguish whether the auto-reverse is operated and the reproduction of the B side is started or the auto-reverse does not work and the stop mode is entered.

[0038]

However, in the player 1 and the receiver 6 described above, the mode signals S45, S46.
Presence / absence and the channels of the audio signals L and R to which the mode signals S45 and S46 are added are combined to notify the receiver 6 of the operation mode of the player 1. Therefore, too much information is received by the receiver 6. Can not be displayed.

For example, in addition to the operation modes of FIG. 6, presence / absence of a cassette (tape 2) of the player 1 type of cassette (tape 2) noise reduction circuit on / off reproduction mode is reverse reproduction mode / repeat reproduction mode fast forward When is finished, enters stop mode / enters playback mode When rewinding is completed, enters stop mode / enters playback mode Automatic cueing in fast forward direction / not automatic cueing in rewinding direction When there is an operation mode or condition such as skipping / not skipping by fast-forwarding during non-recording during playback, receiver 6
Even if an attempt is made to display it on the LCD 82, it cannot be displayed.

Therefore, it is necessary to increase the number of mode signals S45 and S46 in order to display the above-mentioned operation modes and states, and the number of mode signals relative to the number of operation modes and states to be displayed. Must be exponentially increased.

However, when increasing the number of mode signals, it is necessary to provide the player 1 with as many oscillation circuits as the number of mode signals. Further, the detection circuits 85 and 8 of the receiver 6
In FIG. 6, it is necessary to provide a filter for separating each mode signal with twice the number of the mode signals (twice because there are channels of signals L and R). Moreover, when many mode signals are frequency-multiplexed, high precision and resolution are required for the separation filter.

If the number of mode signals increases, the FM signal SL of the audio signals L and R which are the main signals.
, SR must be reduced in degree, so that the S / N ratio of the audio signals L and R becomes disadvantageous.

Therefore, increasing the number of mode signals to display many operation modes is not practical in view of cost, size, weight or characteristics of the player 1 and the receiver 6, and is not practical. .

On the contrary, if the player 1 has various operation modes but cannot display them in a distinct manner, the user may have a trouble such as a failure or an operation error as described above. Therefore, the number of operation modes and states that the player 1 can adopt is limited by the amount of information that can be displayed.

The present invention is intended to eliminate the above problems.

[0046]

By the way, as is the case with the player 1 described above, a headphone type stereo cassette player is generally provided with a microcomputer for system control. However, the processing contents of this microcomputer are not so complicated and the processing speed is not required to be so high.

On the other hand, the original oscillation frequency of a so-called digital timepiece is set to 32.768 kHz, but the crystal oscillator for oscillation is mass-produced and the cost is low.

Therefore, a microcomputer for system control of a headphone type stereo cassette player often uses a crystal oscillator of a digital timepiece as a crystal oscillator for clock oscillation. Alternatively, a crystal oscillator derived from the crystal oscillator of a digital watch is used. Therefore, the clock frequency of the microcomputer of the headphone type stereo cassette player is generally 32.768 kHz. This is also the case with the player 1 described above.

In view of the above points, the present invention uses the clock of the microcomputer 40 to notify the receiver 6 of the operation mode of the player 1.

That is, in the present invention, when the reference numerals of the respective parts correspond to the embodiments described later, for example, in the audio equipment 1 which transmits the audio signals L and R wirelessly, a microcomputer for system control is used. 40 and this microcomputer 40
A modulation circuit 102 which amplitude-modulates the clock SCK from the signal S by the information signal DMD related to the audio signals L and R,
The modulated signal SMD from the modulation circuit 102 is added to the audio signal L to form a frequency multiplexed signal (L + SMD), and the frequency multiplexed signal (L + SMD) from the adder circuit 22L is transmitted. And a transmission circuit 20.

[0051]

The information signal DMD is converted into the modulated signal SMD using the clock SCK as the subcarrier signal, and the modulated signal SMD is obtained.
Frequency multiplexed signal of MD and audio signal L (L + SM
D) is transmitted to the dedicated receiver 6.

[0052]

1 and 2 show a player 1 according to the present invention.
And an example of the receiver 6 thereof. And player 1
Are the circuits 45 to 47 and the adder circuit 2 of the player 1 of FIG.
Except for 2R, the configuration is similar. Although not shown, the player 1 can run the tape 2 in the forward direction or the reverse direction, and has a reverse reproduction function and a repeat reproduction function.

In the microcomputer 40, the player 1
The mode data DMD indicating the operation mode and the like are formed. In this case, the mode data DMD is, for example, as shown in FIG.
(LSB) indicates the presence / absence of the cassette (tape 2) of the player 1, bit 1 indicates whether the reproduction mode is set to the reverse reproduction mode or the repeat reproduction, and bit 2 indicates A of the cassette. It indicates which side, B or B, is being reproduced.

Further, bits 6 to 3 indicate the operation mode of the player 1. For example, these bits are "0".
"001" indicates that the player 1 is in the reproduction mode, and "0010" indicates that the player is in the fast-forward mode. Since bits 6 to 3 are 4 bits, illustration is omitted. , 16 operation modes can be represented.

The mode data DMD is serially output from the microcomputer 40 as shown in FIG. 3A, for example, and represents bits "0" and "1" depending on the difference in pulse width. Further, when the mode data DMD is output from the microcomputer 40,
As shown in, the data DMD is preceded by a predetermined period of "1".
And then the synchronization pulse S that remains "0" for a predetermined period
YN is added. Then, while the power of the player 1 is turned on, the data DMD having this synchronization pulse SYN is repeatedly output from the microcomputer 40 as shown in FIG. 3C.

The mode data DMD having the synchronizing pulse SYN is supplied to the modulation circuit 102 as a modulation signal, and the clock SCK is taken out from the microcomputer 40. The clock SCK is supplied to the modulation circuit 102 through the amplifier 101. It is supplied as the subcarrier signal. As described above, the frequency of the clock SCK at this time is 32.768 kHz.

Thus, in the modulation circuit 102, as shown in, for example, FIGS. 4A to 4C, the clock SCK is amplitude-modulated (PAM-modulated) by the mode data DMD, and the clock SCK is generated only when the level of the mode data DMD is "1". Is extracted as a modulated signal SMD.

The modulated signal SMD is supplied to the high-pass filter 103 to remove the audible band signal component (mainly the data DMD), and the audible band component-removed signal SMD is supplied to the adding circuit 22L. Is added to the audio signal L of the left channel. Therefore, the addition circuit 22L extracts the addition signal (L + SMD) in which the modulated signal SMD (subcarrier frequency is 32.768 kHz) is frequency-multiplexed with the audio signal L.

Then, this addition signal (L + SMD) is converted into the FM signal SL as in the case of FIG. 8, and this FM signal SL is transmitted to the receiver 6 together with the FM signal SR of the right channel. At this time, since the signal SMD has passed through the high pass filter 103, it has a differential waveform as shown in FIG. 4D.

On the other hand, in the receiver 6, the demodulation circuit 68
The addition signal (L + SMD) is extracted from L, and the demodulation circuit 6
The audio signal R is extracted from 8R. For this reason,
A high-cut characteristic for removing the modulated signal SMD is also added to the de-emphasis circuit 69L (and 69R), and only the audio signal L is supplied to the amplifier 69L.

Further, the addition signal (L + SMD) from the demodulation circuit 68L is supplied to the high-pass filter 601, the modulated signal SMD is extracted, and this signal SMD is supplied to the waveform shaping circuit 602, as shown in FIG. 4C. The original binary signal SMD is shaped and this binary signal S
MD is supplied to the microcomputer 80.

Then, in the microcomputer 80, the bit pattern of the original mode data DMD is decoded from the supplied signal SMD to detect the operation mode of the player 1 and the like, and the LC is output according to the detection output.
The drive signal of D82 is supplied, and the operation mode of the player 1 and the like are displayed on the LCD 82.

Thus, according to the present invention, for example, 7-bit mode data DMD is formed, and this mode data DMD is formed.
The receiver 6 indicates the operation mode and status of the player 1 by MD.
Therefore, even if the player 1 has various operation modes and states, these can be appropriately displayed.

Since the amount of information that can be displayed is large, even if the player 1 has many operation modes and states,
The user can know it correctly, and therefore, the operation modes and functions of the player 1 can be increased.

Further, the number of bits of the mode data DMD is increased even if the number of operating modes, states, etc. is increased, while the oscillation circuits and detection circuits such as the oscillation circuits 45, 46 and the detection circuits 85, 86 are unnecessary. It is sufficient, and there is no need to provide or add an oscillation circuit or a detection circuit. Therefore, it is advantageous in terms of cost, size, weight and characteristics.

Further, even if the number of operation modes and states increases, F by the main audio signals L and R
Since it is not necessary to reduce the modulation degree of the M signals SL and SR, the S / N ratio of the audio signals L and R can be kept good. Further, the mode data DMD can be formed only by changing the program of the microcomputer 40 and does not require addition of special hardware.

Further, since the clock SCK of the microcomputer 40 for system control is used as the subcarrier signal when transmitting the mode data DMD, it is not necessary to provide an oscillation circuit for the subcarrier signal, which is also cost effective. Is advantageous to.

Furthermore, the clock SCK of the microcomputer 40 is
Since it is used as a subcarrier signal when transmitting the mode data DMD, its frequency stability is high, and stability during modulation and demodulation is improved.

In the modulation in the modulation circuit 102, the clock SCK is set to the mode data D as shown in FIGS.
Since it only needs to be gated by MD, it has a very simple structure and is low cost.

Further, even if there are differences in the operation mode and functions depending on the model of the player 1, the circuit according to the present invention can be used in common and it is not necessary to prepare for each model.

In the above description, the present invention is applied to a headphone type stereo cassette player, but the present invention is also applied to a player using a CD, MD, DAT, DCC or the like as a recording medium. Can be applied.

Alternatively, when a cordless telephone is used to operate an answering machine function of a parent device from a child device, or when a karaoke device is used to select music or pitch control the main body from a wireless microphone, an identification code is registered with a specific low power receiver. The present invention can also be applied to the case where the name corresponding to the identification code is displayed on the receiving side.

[0073]

According to the present invention, for example, 7-bit mode data DMD is formed, and the operation mode and state of the player 1 are notified to the receiver 6 by this mode data DMD. Even if there are various operation modes and states, it is possible to display them appropriately.

Since the amount of information that can be displayed is large, even if the player 1 has many operation modes and states,
The user can know it correctly, and therefore, the operation modes and functions of the player 1 can be increased.

Further, even if the number of operation modes and states increases, it is only necessary to increase the number of bits of the mode data DMD, and it is not necessary to provide or add an oscillation circuit or a detection circuit. Therefore, it is advantageous in terms of cost, size, weight and characteristics.

Further, even if the number of operation modes and states increases, F by the audio signals L and R which are main signals
Since it is not necessary to reduce the modulation degree of the M signals SL and SR, the S / N ratio of the audio signals L and R can be kept good. Further, the mode data DMD can be formed only by changing the program of the microcomputer 40 and does not require addition of special hardware.

Further, since the clock SCK of the microcomputer 40 for system control is used as the subcarrier signal when transmitting the mode data DMD, it is not necessary to provide an oscillation circuit for the subcarrier signal, which is also cost effective. Is advantageous to.

Further, the clock SCK of the microcomputer 40 is
Since it is used as a subcarrier signal when transmitting the mode data DMD, its frequency stability is high, and stability during modulation and demodulation is improved.

Further, in the modulation in the modulation circuit 102, the clock SCK is set to the mode data D as shown in FIGS.
Since it only needs to be gated by MD, it has a very simple structure and is low cost.

Furthermore, even if there are differences in the operation mode and functions depending on the model of the player 1, the circuit according to the present invention can be used in common and it is not necessary to prepare for each model.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a player according to the present invention.

FIG. 2 is a system diagram showing an example of a receiver according to the present invention.

FIG. 3 is a waveform diagram for explaining the operation of an example of the present invention.

FIG. 4 is a waveform chart for explaining the operation of an example of the present invention.

FIG. 5 is a diagram showing a relationship between mode data and operation modes.

FIG. 6 is a diagram showing a relationship between a mode signal and an operation mode.

FIG. 7 is a perspective view for explaining the present invention.

FIG. 8 is a system diagram showing an example of a player for explaining the present invention.

FIG. 9 is a system diagram showing an example of a receiver for explaining the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Headphone type stereo cassette player 6 Dedicated receiver 7 Headphones 10 Playback circuit 20 Transmission circuit 30 Tape running control means 40 Microcomputer 50 Reception circuit 60 Reception circuit 80 Microcomputer 82 LCD 90 Transmission circuit 102 Modulation circuit 103 High-pass filter 601 High-pass filter 602 Waveform shaping circuit DMD mode data SCK clock SMD modulated signal

Claims (4)

[Claims] 1. In an audio device adapted to wirelessly transmit an audio signal, a modulating circuit for amplitude-modulating a clock used internally by an information signal related to the audio signal, and a modulated circuit from the modulating circuit. A wireless audio device for audio signals, comprising: an adder circuit that adds a signal to the audio signal to form a frequency multiplexed signal; and a transmission circuit that transmits the frequency multiplexed signal from the adder circuit. 2. An audio device for wirelessly transmitting an audio signal, comprising: a microcomputer for system control; and a modulation circuit for amplitude-modulating a clock from the microcomputer with an information signal related to the audio signal. A wireless audio system having an adder circuit for adding a modulated signal from the modulator circuit to the audio signal to form a frequency multiplexed signal, and a transmitter circuit for transmitting the frequency multiplexed signal from the adder circuit machine. 3. An audio device in which an operation mode and the like are controlled by a microcomputer for system control, and a modulation circuit which amplitude-modulates a clock from the microcomputer with an information signal indicating the operation mode and the like. A wireless audio system including an adder circuit for adding a modulated signal from a modulator circuit to a reproduced audio signal to form a frequency multiplexed signal, and a transmitter circuit for transmitting the frequency multiplexed signal from the adder circuit. machine. 4. A receiving circuit for receiving a signal transmitted from the transmitting circuit according to any one of claims 1 to 3, and the audio signal and the modulated signal separated from the frequency multiplexed signal extracted from the receiving circuit. And a display element for displaying data according to an information signal modulating the extracted modulated signal.