JPH08320154A - Portable telephone set - Google Patents

Abstract

PURPOSE: To reduce mixing of surrounding noise into an acoustic voice and perform a transmittance of communication sound at a silent place having a less amount of surrounding noise without reducing its quality. CONSTITUTION: A portable type telephone set for use in mobile communication is operated such that surrounding noise is collected by a microphone 9, a surounding noise signal outputted from the microphone 9 is divided into a plurality of frequencies by a noise level sensing circuit 11 comprised of BPF and a level sensor, each of the noise levels is detected and this noise level is discriminated by a control part 13, thereby an output of a transmittance signal of the frequency component from the microphone 1 corresponding to the level when it is more than a predetermined level is cut by a predetermined amount and then a frequency characteristic of the transmittance signal is changed by a frequency characteristic correction circuit 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable telephone device for mobile communication such as a portable telephone and a personal handyphone system (hereinafter abbreviated as PHS).

[0002]

2. Description of the Related Art FIG. 2 shows the configuration of a conventional portable telephone device.

In FIG. 2, 1 is a microphone for picking up the voice of the caller, 2 is a microphone amplifier for amplifying the output signal of the microphone 1,
Reference numeral 3 is a transmitter signal converter for adapting the output signal from the microphone amplifier 2 to various signal systems in mobile communication, and 4 is a transmission / reception unit. Further, 5 is a signal converter for reception which converts a signal received by the transmitting / receiving section 4 into a voice signal, 6
Is a receiver amplifier that amplifies a voice signal, 7 is a receiver that gives an acoustic output to the ear of the caller, and 8 is a signal converter 3, 5,
And a control unit including a CPU for controlling the transmission / reception unit 4.

Next, the operation of the above-mentioned conventional example will be described focusing on the transmission path. The voice of the speaker picked up by the microphone 1 is converted into an electric signal, appropriately amplified by the microphone amplifier 2, and then converted by the signal converter 3 into a signal according to the signal system of mobile communication, and the transmitter / receiver 4 To the base station etc.

As described above, in the above-mentioned conventional portable telephone device, the voice of the speaker can be transmitted on the radio wave to the base station or the like.

[0006]

However, in the above-mentioned conventional call circuit, since it is a portable telephone, there is a contradiction between convenience and call quality.

That is, the smaller the size of the telephone is to make it easier to carry, the greater the distance between the microphone and the mouth when the receiver is placed on the ear during a call. Therefore, the output of the microphone becomes small and the volume becomes insufficient,
It is necessary to increase the amplification factor of the microphone amplifier to secure the necessary volume for the telephone. However, if you increase the amplification factor,
Not only the voice of the speaker but also the ambient noise becomes loud at the same time, the S / N ratio between the voice and the ambient noise becomes worse, and as a transmission characteristic of the portable handset often used in a place where the ambient noise is large such as outdoors. Is a major drawback.

Therefore, conventionally, it is possible to increase the S / N ratio by giving the microphone amplifier a frequency characteristic that cuts a frequency band having a large influence in the noise frequency band.

However, since the frequency characteristics of the microphone amplifier are fixed, the S / N ratio is rather deteriorated under noises of different frequency bands, and a specific frequency is cut in a call in a quiet place without noise. Since it is kept as it is, there is a problem that the naturalness of the transmission is impaired and the sound quality is not similar to the voice of the speaker.

The present invention solves such a conventional problem by reducing the mixing of ambient noise into the voice and transmitting the call sound in a quiet place with little ambient noise without impairing the sound quality. An object of the present invention is to provide an excellent portable telephone device that can be used.

[0011]

In order to achieve the above object, the present invention divides an ambient noise signal output from this microphone into a plurality of frequency bands, and a microphone that collects ambient noise in a portable telephone device. And a noise level detecting means for detecting the noise level, and when the detected noise level is equal to or higher than a preset level, the transmission signal of the frequency component corresponding to the noise level is cut off by a predetermined amount. And a frequency characteristic correcting means for changing the frequency characteristic of.

[0012]

Therefore, according to the present invention, the frequency characteristic of the ambient noise is automatically detected, and the frequency characteristic of the transmission signal is determined to be optimum according to the detection result. Then, a large part of the power of the frequency component included in this ambient noise is cut, the S / N ratio is secured, and clear communication is possible. In a place with little ambient noise, the transmission signal faithfully transmits the original sound. The flatness becomes the frequency characteristic, and good speech quality can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of a portable telephone device of the present invention.

In FIG. 1, the same components as those in FIG. 2 are designated by the same reference numerals. In the portable telephone device of this embodiment, a microphone 1 for voice pickup, its microphone amplifier 2, and microphone amplifier 2 are used. Signal converter 3 for adjusting the output signal of the mobile phone to the signal system of mobile communication, a transmitter / receiver unit 4 for communicating with the other party, and a receiver signal converter 5 for converting the signal received by the transmitter / receiver unit 4 into a voice signal. A microphone 9 for picking up ambient noise of the portable telephone device and a microphone for amplifying a noise signal output from the microphone 9 in addition to the receiver amplifier 6 and the receiver 7 for amplifying the audio signal output from the signal converter 5. The amplifier 10 and a plurality of bandpass filters (hereinafter referred to as BPFs) that extract the frequency of the noise signal output from the microphone amplifier 10 by dividing the frequency into a plurality of bands.
Abbreviated as 11A ₁ , 11A ₂ , 11A ₃ ... And a plurality of level detection sections 11B ₁ , 11 for detecting the output signal levels of the respective BPFs 11A ₁ , 11A ₂ , 11A ₃ .
A noise level detection circuit 11 composed of B ₂ , 11B ₃ ...
And a frequency characteristic correction circuit 1 that is connected between the voice microphone amplifier 2 and the signal converter 3 and corrects the frequency characteristic of the transmission signal.
2 and a control unit 13 including a CPU for controlling the signal converters 3 and 5 and the transmission / reception unit 4 and controlling the frequency characteristic correction circuit 12 based on the output signal from the noise level detection unit 11.

Next, the operation of this embodiment will be described.
The microphone 9 is arranged at a position where ambient noise of the mobile phone can be easily picked up (for example, the rear surface of the receiver), the ambient noise is picked up by the microphone 9 and converted into an electric signal, and the noise is amplified by the microphone amplifier 10. Output to the level detection circuit 11. In the noise level detection circuit 11, the BPF1
1A ₁ , 11A ₂ , 11A ₃ ... Divide into a plurality of frequency bands, and each level is detected by the level detection circuit 11B.
₁ , 11B ₂ , 11B ₃ ... Detects and outputs the detection signal to the control unit 13.

The control unit 13 determines whether the noise level of each frequency band detected by the noise level detection unit 11 is higher than a preset level, and responds to the noise level above the set level for reducing the S / N ratio. A correction command signal for cutting the output of the transmission signal of the frequency component to be output by a predetermined amount is output to the frequency characteristic correction circuit 12. As a result, the frequency characteristic of the microphone amplifier 2 that amplifies the transmission signal is corrected and controlled to the optimum frequency characteristic.

[0017] For example, the ambient noise in such crowded high-traffic, since the overwhelming majority frequency components of 300～500H _z, the frequency characteristic correcting circuit 12 is 300～500H _z
It acts so as to create a characteristic of cutting the transmission signal of the above to about -6 dB / DC. Further, since all components have low levels in a quiet place, the frequency characteristic correction circuit 12 maintains a flat characteristic.

As described above, according to the above-mentioned embodiment, there is an advantage that the optimum frequency characteristic of the transmission signal according to the ambient noise is automatically obtained.

The noise level detection circuit 1 of the above embodiment
Although the 1 and the frequency characteristic correction circuit 12 may be all configured by analog circuits, they may be realized by a signal processing method by DSP (digital signal processor) after A / D conversion. With a small amount of hardware, fine control is possible.

[0020]

As is apparent from the above embodiment, the present invention is as follows.
The ambient noise is divided into multiple frequency bands, the level is detected, and when the detected level is higher than the set value, the output of the voice signal of the frequency component corresponding to this is cut by a predetermined amount and the voice signal is transmitted. Since the frequency characteristic of is changed optimally, clear speech can be obtained regardless of the type of noise.

Further, when the ambient noise is small, it can be transmitted without impairing the nature of the voice of the speaker.

[Brief description of drawings]

FIG. 1 is a block diagram of a portable telephone device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional mobile phone device.

[Explanation of symbols]

1 microphone 2 microphone amplifier 3 the signal converter 4 transceiver 5 the signal converter 6 receiver amplifier 7 Receiver 9 noise microphone 10 microphone amplifier 11 noise level detecting circuit _{11A 1 ~11A 3 BPF 11B 1 ~11B} 3 level detector 12 frequency characteristic correction Circuit 13 Control unit

Claims (1)

[Claims] 1. A portable telephone device for mobile communication, comprising a microphone that collects ambient noise, and an ambient noise signal output from the microphone that is divided into a plurality of frequency bands to detect the noise level. Noise level detection means, and when the detected noise level is equal to or higher than a preset level, the output of the transmission signal of the frequency component corresponding to the noise level is cut by a predetermined amount to change the frequency characteristic of the transmission signal. A portable telephone device comprising frequency characteristic correction means.