JPH1022738A - Rf direct modulation device and transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device modulating an audio band signal into an RF frequency signal with a simple configuration and to provide the transmitter- receiver conducting radio communication with a simpler configuration than that of a conventional radio system by using the device. SOLUTION: In the RF direct modulation device, a vibration provision mechanism 13 provides a mechanical vibration based on a voice input to a piezoelectric vibrator 11 vibrated in the resonance frequency in an oscillation circuit 12 so as to obtain a signal where an audio band signal component is superimposed on a carrier signal with a resonance frequency of the piezoelectric vibrator 11. The transmitter-receiver is provided with a low pass filter in addition to the modulation device in which the low pass filter extracts the audio band signal component from the modulated signal so as to demodulate the signal component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio input signal
The present invention relates to a device for directly modulating an F-band signal and a transceiver using the device, and more particularly to a modulation device and a transceiver suitable for use in a simple wireless system such as a transceiver.

[0002]

2. Description of the Related Art Transceivers (specific low-power radio telephones)
In general, a transmission / reception system of the FM modulation method is used in such wireless information communication systems. FIG. 5 shows a configuration example of a transmission / reception circuit of a conventional transceiver. In this example, an FM modulation circuit 5 composed of a PLL and a VCO
1 to FM-modulate the audio band data signal,
The signal after the modulation is amplified through a transmitter / receive switch 52 and then transmitted through a band-pass filter 53. At the time of reception, a signal obtained by amplifying the received signal by an RF amplifier 55 through a band-pass filter 54 is First and second mixing circuits 5
A method of lowering to the audio band via 6, 57 is adopted.

[0003]

By the way, the conventional radio communication system using the FM modulation method as described above has an advantage that noise is hardly mixed and distortion of a demodulated signal can be suppressed. There is a problem that the configuration becomes considerably complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device capable of modulating an audio band signal into an RF frequency signal with a simpler configuration, and a simpler device using the device than a conventional wireless system. An object of the present invention is to provide a transceiver capable of performing wireless communication with a simple configuration.

[0005]

In order to achieve the above object, an RF direct modulation device of the present invention comprises an oscillation circuit 12 including a piezoelectric vibrator 11, as shown in FIG. The piezoelectric vibrator 11 includes a vibration imparting mechanism 13 for applying mechanical vibration based on a voice input to the piezoelectric vibrator 11, and an output circuit 14 for extracting an output of the oscillation circuit 12. It is characterized by being configured to output a signal in which a signal component of an audio band is superimposed on a carrier signal of a frequency.

As shown in FIG. 3 showing an embodiment of a transceiver according to the present invention, an RF direct modulation device 10 having the above configuration and an RF direct modulation device 10
And a low-pass filter 30 for receiving a signal of the same type from outside and transmitting and receiving the same type of signal from the outside, and a low-pass filter 30 for receiving a signal received by the transmitting and receiving antenna 20 and extracting a signal component of an audio band. It is characterized by having.

According to the present invention, the resonance frequency of a piezoelectric vibrator is set as a carrier frequency, the bias of the carrier signal is changed by applying mechanical vibration to the piezoelectric vibrator from the outside, and the change in the bias is transmitted as a signal. What you want to do.

That is, in the configuration of the RF direct modulation device of the present invention, when mechanical vibration is applied to the piezoelectric vibrator 11 by the vibration applying mechanism 13, a voltage signal corresponding to the vibration is generated. When mechanical vibration is externally applied to the piezoelectric vibrator 11 vibrating at a predetermined resonance frequency by driving the oscillation circuit 12, the output of the oscillation circuit 12 becomes a resonance signal of the piezoelectric vibrator 11. The signal is a signal on which a voltage signal caused by mechanical vibration is superimposed. For example, several tens of MHz
When mechanical vibration in the audio band is applied to the piezoelectric vibrator 11 resonating at a constant frequency of about several hundred MHz to several tens MHz to several hundred MHz from the oscillation circuit 12.
The signal whose bias of the high frequency signal changes at the frequency of the audio band can be extracted.

By passing such a signal through a low-pass filter, it is possible to easily extract only a bias change amount, that is, only an audio band signal applied to the piezoelectric vibrator 11 by the vibration applying mechanism 13.

In the transceiver of the present invention, in addition to the RF direct modulation device 10 and the transmitting / receiving antenna 20 of the present invention for transmitting the above-described signals, a low-pass filter 30 for extracting a signal in an audio band is provided. A signal received by the antenna 20 is passed through a low-pass filter 30 to extract a signal component of an audio band, which is a bias component of the signal, and demodulate the received signal.

According to such a transceiver of the present invention, a circuit configuration can be greatly simplified, for example, a mixing circuit is not required at the time of demodulation as compared with a conventional FM modulation type transceiver. Becomes

Here, according to the modulation / demodulation method of the present invention,
Although the function of suppressing low-frequency noise or distortion of a transmission signal is inferior to that of the FM modulation method, it is sufficiently applicable to simple radio such as a transceiver.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing an embodiment of an RF direct modulation device according to the present invention. Piezoelectric vibrator 1
Reference numeral 1 denotes a known device in which electrodes are formed on both surfaces of a piezoelectric substrate. The piezoelectric vibrator 11 is incorporated in an oscillation circuit 12, and resonates at a predetermined resonance frequency by driving the oscillation circuit 12. The resonance frequency of the piezoelectric vibrator 11 is, for example, about several tens MHz to several hundred MHz.

The oscillation output of the oscillation circuit 12 is taken out to the outside via the amplifier 14. The amplifier 14 functions as a buffer for preventing the influence of an external circuit from affecting the oscillation circuit 12, and the amplifier 14 constitutes an output circuit.

The piezoelectric vibrator 11 is provided with a mechanical vibration of an audio band based on a voice input by a vibration applying mechanism 13. The vibration applying mechanism 13 includes a dynamic microphone 13a and an amplifier 13 for amplifying the output of the dynamic microphone 13a.
b, and a solenoid coil 13d containing a movable magnetic core 13c operated by the output of the amplifier 13b. The distal end surface of the movable magnetic core 13c is arranged so as to be in contact with the surface of the piezoelectric vibrator 11. With this configuration, the movable magnetic core 13c vibrates in response to an audio signal input via the dynamic microphone 13a, and the mechanical vibration is transmitted to the piezoelectric vibrator 11.

In the above embodiment, the oscillation circuit 12
Is driven to cause the piezoelectric vibrator 11 to resonate, a voltage signal of the resonance frequency of the piezoelectric vibrator 11 is extracted from the amplifier 14 as schematically shown in FIG. When an audio signal is input from the dynamic microphone 13a in this state, mechanical vibration corresponding to the audio input is applied to the piezoelectric vibrator 11 through the movable magnetic core 13c, and a voltage signal corresponding to the mechanical vibration is generated. 2B, a signal in which a voltage signal of an audio band is superimposed on a voltage signal of a resonance frequency of the piezoelectric vibrator 11, as schematically shown in FIG. That is, a signal in which the bias of the carrier signal is changed by voice input is taken out with the resonance frequency of the piezoelectric vibrator 1 as the carrier frequency.

The RF direct modulation device of the present invention as described above is used, for example, by being incorporated into a transceiver for simple radio as described below. FIG. 3 is a block diagram showing a circuit configuration of a transceiver according to an embodiment of the present invention.

In FIG. 3, the RF direct modulation device shown in FIG. 1 is designated by the reference numeral 10, and the output of the amplifier 14 of the RF direct modulation device 10 is input to an amplifier (power amplifier) 21 to obtain a required output level. To be amplified. The output of the amplifier 21 is guided to a transmitting / receiving antenna 20 via an antenna switch 22.
Is configured to be transmitted to the outside by radio waves.

On the other hand, the signal received by the transmitting / receiving antenna 20 is guided to the low-pass filter 30 via the antenna switch 22. The low-pass filter 30 is a filter for passing a frequency component of an audio band and cutting off a frequency component higher than the audio band.
After being amplified by 1, it is configured to be guided to a speaker 32 and converted into an audio output.

In the transceiver having the above configuration, R
By inputting an audio signal from the dynamic microphone 13a of the F direct modulation device 10, the bias of the signal changes based on the audio input with the resonance frequency of the piezoelectric vibrator 11 as a carrier frequency, as shown in FIG. While being transmitted after being modulated into such a signal, at the time of receiving such a signal, only the signal in the audio band, which is the bias component thereof, is extracted by the low-pass filter 30, as shown in FIG. The signal is demodulated into a signal and converted into an audio output by the speaker 32.

Incidentally, the RF direct modulation device of the present invention
The vibration applying mechanism 13 is not limited to the above-described embodiment, but any mechanism may be used as long as it can apply mechanical vibration to the piezoelectric vibrator 11 based on voice input. be able to. That is, for example, as shown in FIG.
1 is fixed, and the other end of the cantilever 41 is vibrated by an external sound input.
A structure or the like that is in contact with or fixed to the device can be adopted.

[0022]

As described above, according to the RF direct modulation device of the present invention, a piezoelectric vibrator incorporated in an oscillation circuit and vibrating at a predetermined resonance frequency is based on an external voice input. By applying mechanical vibration, a signal in which the audio band signal is superimposed on the resonance frequency signal of the piezoelectric vibrator, that is, a signal whose bias changes based on the audio input with the resonance frequency of the piezoelectric vibrator as the carrier frequency Modulated. By passing the modulated signal through a low-pass filter, it is possible to easily extract and demodulate the signal component of the audio band, which is the bias component, and to reduce the frequency of the signal compared to the conventional FM modulation method. Although the influence of noise increases to some extent, it can be sufficiently applied as a modulation method in a simple wireless system such as a transceiver.

In the transceiver according to the present invention, the above-described RF direct modulation device is provided as a modulation circuit, and a low-pass filter is provided as a demodulation circuit. This makes it possible to greatly simplify the circuit configuration for modulation and demodulation as compared with a transmitter and receiver employing the conventional FM modulation method. It is possible to greatly reduce.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an RF direct modulation device of the present invention.

FIGS. 2A and 2B are schematic diagrams showing signal waveforms of respective units in each embodiment of the present invention, wherein FIG. 2A shows an output signal of the oscillation circuit 12 in a state where there is no audio input, and FIG. (C) shows an output signal of the oscillation circuit 12, and (C) shows a demodulated signal that has passed through the low-pass filter 30.

FIG. 3 is a block diagram showing a circuit configuration of an embodiment of the transceiver according to the present invention;

FIG. 4 is a schematic diagram showing a main part configuration of another embodiment of the RF direct modulation device of the present invention.

FIG. 5 is a block diagram showing an example of a circuit configuration of an FM modulation type transceiver used in a conventional transceiver and the like.

[Explanation of symbols]

 Reference Signs List 10 RF direct modulation device 11 Piezoelectric vibrator 12 Oscillation circuit 13 Vibration imparting mechanism 13a Dynamic microphone 13b Amplifier 13c Moving magnetic core 13d Solenoid coil 14 Amplifier (output circuit) 20 Transmitting / receiving antenna 21 Amplifier 22 Antenna switch 30 Low-pass filter 31 Amplifier 32 Speaker

Claims (2)

[Claims] An oscillation circuit including a piezoelectric vibrator, a vibration applying mechanism for applying mechanical vibration to the piezoelectric vibrator based on a voice input, and an output circuit for extracting an output of the oscillation circuit, An RF direct modulation device configured to output a signal in which a signal component of an audio band is superimposed on a carrier signal having a resonance frequency of the piezoelectric vibrator from the output circuit. 2. The RF direct modulation device according to claim 1, a transmission / reception antenna for transmitting an output signal from the RF direct modulation device and receiving the same kind of signal from the outside, and the transmission / reception antenna. A transceiver having a low-pass filter for inputting a reception signal according to (1) and extracting a signal component of an audio band.