JP3027641B2 - Voice control device for wireless telephone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice control device for a radio telephone such as a cordless telephone, and more particularly to a voice control device for a radio telephone in consideration of a use environment noise level.

[0002]

2. Description of the Related Art A radiotelephone is convenient for a user in that it can be used anywhere as compared with a fixed telephone. However, since the place of use is arbitrary, it is more susceptible to external noise than a fixed type, and often uses nerves for communication. The volume control of a conventional wireless telephone to achieve such an object is performed by switching a volume switching switch added to the telephone. The volume switching switch includes both continuous switching and discrete switching. In any case, the switch is manually switched by the caller based on the judgment of the caller.

[0003]

However, even if the volume switching switch is used, the transmission volume (the gain of the transmission microphone amplifier) is constant, so that in a place where the environmental noise is large, the communication partner can be used. In this case, the voice S / N ratio is lowered, and the intelligibility is lost. Further, when making a call in a place where the environmental noise is large, the operator thinks that it is difficult to transmit his / her own voice to the other party, and transmits a loud voice. In a wireless telephone, a limiter circuit is provided so that a side band of a radio wave to be used is not excessively spread or an amplitude is not overmodulated. Therefore, when a voice is transmitted in a loud voice, a limiter is applied and the waveform of the voice is distorted, and the clarity is reduced. In such a case, automatic gain control of the transmission microphone amplifier is performed. In a normal method, the gain control is often performed by detecting and amplifying a signal input from the transmission microphone. Therefore, the control level fluctuates depending on the presence or absence of the transmission voice, and the reception level of the other party also sounds unnatural in conjunction with this.

An object of the present invention is to provide a voice control device for a radio telephone which can maintain a clear telephone call even in a place where environmental noise is large.

[0005]

According to the present invention, a noise level detecting microphone is installed at a position different from a transmitting microphone, and a difference between the transmitting microphone and the noise level detecting microphone is used as a transmitting output. Item 1).

Further, according to the present invention, the noise level detecting microphone is set at a position behind the transmitting microphone.

Further, according to the present invention, the gain of the variable gain amplifier for transmitting and the variable gain amplifier for receiving is controlled by the output of the noise level detecting microphone (claim 3).

[0008]

According to the present invention, the noise mixed in the transmission microphone and the noise mixed in the noise level detection microphone are canceled by the difference.

Further, according to the present invention, since the noise level detecting microphone is installed at the back position of the transmitting microphone, the mixing of the call voice is small, and only the noise becomes the noise level detecting microphone mixed similarly. It is suitable for removing noise (claim 2).

Further, according to the present invention, since the gains of the variable gain amplifiers for transmission and reception are changed according to the magnitude of the noise, it is possible to make a telephone call substantially unaffected by noise. Claim 3).

[0011]

1 (a) to 1 (c) show an embodiment of a wireless telephone according to the present invention. 1A is a front view, FIG. 1B is a side view, and FIG. 1C is a rear view. The wireless telephone 1 includes a receiver 2 for reception, a microphone 3 for transmission, a push button 6,
Although the antenna 5 is provided, the present embodiment is characterized in that the noise level detection microphone 4 is provided at the back position of the transmission microphone 3. The microphone 4 may have the same performance as the transmitting microphone 3, but may be inferior in performance because it is intended to detect only noise.

The reason why the microphone is installed on the back is that the voice of the caller is difficult to reach, but the noise can be detected in common with the microphone 3 for transmission. Here, the noise refers to environmental noise existing in the surrounding space with relatively low directivity, not from the caller himself.

FIG. 2 is an embodiment of the electric circuit in the telephone. In the present embodiment, preamplifiers 10 and 11, a difference device 12,
Detector 13, amplifier 14, variable gain amplifiers 15, 16,
It comprises a receiver amplifier 17, microphones 3, 4 and a receiver 2. The preamplifiers 10 and 11 are amplifiers for detecting the amplitudes of the detected sounds from the microphones 3 and 4 to be very small. The output of the preamplifiers 10 and 11 enters a differentiator 12 to obtain a difference output between the two. By taking the difference, the noise that enters the microphones 3 and 4 in common is canceled. This difference output is input to the variable gain amplifier 15, but in this embodiment, this gain is applied to the detector 13 and the amplifier 1
Based on the noise signal obtained in step 4, control is performed so that the noise signal is large if the noise signal is large and large if the noise signal is small. As a result, a transmission voice output that is not affected by noise is obtained, and is transmitted to and transmitted to the modulation circuit for a wireless device.

Further, the gain of the variable gain amplifier 16 on the receiving side is controlled so that the gain is large when the noise is large and the gain is small when the noise is small, contrary to the transmission. Thus, the received voice is also a clear voice that is not affected by noise, and can be easily identified. FIG. 3 shows the concept of the above gain control.

Incidentally, it is conceivable that the voice of the caller is also input to the microphone 4 installed on the back, and therefore, the difference output of the differentiator 12 may be slightly lower than the original voice level. In such a case, the gain control of the variable gain amplifier 15 may be made larger than the gain control of the variable gain amplifier 16. Further, the installation position of the microphone 4 is not limited to the rear surface as long as the microphone 4 is located close to the transmission microphone 3 and the transmission sound is difficult to input. Further, a configuration may be employed in which it is difficult to input a transmission voice.

[0016]

According to the present invention, it is possible to obtain a wireless telephone which is less affected by environmental noise in both transmission and reception.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a wireless telephone according to the present invention.

FIG. 2 is an embodiment diagram of an electric circuit of the present invention.

FIG. 3 is a diagram illustrating the concept of variable gain control according to the present invention.

[Description of Signs] 1 Wireless telephone 2 Receiver for reception 3 Microphone for transmission 4 Microphone for noise level detection 5 Differentiator (subtractor) 15, 16 Variable gain amplifier

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-290248 (JP, A) JP-A-64-20761 (JP, A) JP-A-5-22392 (JP, A) JP-A 63-290 232667 (JP, A) JP-A-63-250951 (JP, A) JP-A-61-214852 (JP, A) JP-A-1-272355 (JP, A) JP-A-2-70152 (JP, A) Hikaru Hei 2-147993 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04M 1/60 H04M 1/00

Claims (1)

(57) [Claims] 1. A transmission microphone of a wireless telephone, a noise level detection microphone installed at a position different from an installation position of the transmission microphone, and a difference between the output of the transmission microphone and the noise level detection microphone , A first variable gain amplifier for inputting an output from the difference means, a means for outputting the output of the first variable gain amplifier to a wireless transmitting means, and a wireless reception wireless input from a partner. A second variable gain amplifier that captures the noise, a means for outputting the output of the second variable gain amplifier to a receiver, and the gain of the first variable gain amplifier when the output from the noise level detection microphone is large. Small and said second
The gain of the variable gain amplifier is increased, and when the output from the noise level detection microphone is small, the gain of the first variable gain amplifier is increased and the gain of the second variable gain amplifier is decreased. And a gain control means for making gain control of the first variable gain amplifier larger than gain control of the second variable gain amplifier.