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JP2001298394

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DESCRIPTION JP2001298394
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
portable telephone apparatus such as a portable telephone and a PHS, and more particularly to a
portable telephone apparatus having an improved output characteristic of a received voice signal.
[0002]
2. Description of the Related Art A portable telephone apparatus such as a portable telephone or
PHS does not always communicate in a quiet atmosphere.
[0003]
There has been proposed a mobile telephone device having a treble emphasis mode in which the
treble range of the output voice is emphasized when communication is performed under a
situation where ambient noise is large.
[0004]
In such a portable telephone apparatus, by operating the mode switch, it is possible to output
voice in the high-frequency range emphasis mode.
08-05-2019
1
As a result, the treble emphasis mode enhances the treble of the output voice, so that the
received voice can be heard relatively clearly even in a situation where the surrounding noise is
large.
[0005]
By the way, when communication is performed in a quiet environment, if the communication is
performed in the high-tone emphasis mode, the output voice becomes unpleasant.
Therefore, it is necessary for the user to operate the mode switch on / off by determining the
surrounding situation.
[0006]
In the prior art, in order to always keep the communication with the other party best, it is
necessary to judge the surrounding situation and perform the on / off operation of the mode
switch, which is not always convenient.
[0007]
In addition, the pitch frequency and formant frequency of the voice signal are different
depending on the person, and the conventional one transmits or receives as it is with respect to
the female “kinkin voice” or the male “boggling voice”. There is a problem that difficult
cases exist.
Furthermore, encoding of the audio signal is performed on the premise of the limitation of the
audio band, and there is a possibility that encoding may not be performed correctly for a
wideband audio signal. If the coding is not correctly performed, there is a problem that the
received speech can not be clearly heard.
[0008]
The present invention has been made in view of the above problems, and has improved the
output characteristics of the received voice signal regardless of the condition of noise derived
from ambient noise, the nature of the voice signal, and the presence or absence of limitation of
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2
the voice band. It is an object of the present invention to provide a mobile telephone device.
[0009]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present
invention adopts means for solving the problems having the following features.
[0010]
The invention described in claim 1 comprises noise detection means (e.g., noise detector 44 in
FIG. 1) for detecting a noise level derived from ambient noise, and level change means (e.g., for
changing a speech signal level to be transmitted). 1 and audio level control means (for example,
ATT control circuit 46 in FIG. 1) for controlling the level changing means in accordance with the
output of the noise detection means.
[0011]
The invention described in claim 2 comprises noise detection means (for example, the noise
detector 44 in FIG. 2) for detecting a noise level derived from ambient noise, and a noise
canceller (for canceling noise in an audio signal to be transmitted). For example, it has a noise
canceller 51) in FIG. 2 and a noise canceller control means (for example, the noise canceller
control circuit 52 in FIG. 2) for controlling the degree of cancellation of the noise canceller
according to the output of the noise detection means. Do.
[0012]
According to the third aspect of the present invention, the pitch frequency and formant
frequency detecting means (for example, the pitch frequency and formant frequency detector 63
in FIG. 3) for detecting the pitch frequency and formant frequency of the audio signal Equalizer
control means (for example, the equalizer control in FIG. 3) for controlling the frequency
characteristics of the equalizer according to the equalizer (for example, the equalizer 48 in FIG.
3) to control the characteristics and the pitch frequency and formant frequency detection means
And the circuit 62).
[0013]
According to a fourth aspect of the present invention, in the mobile telephone apparatus
according to the third aspect, the pitch frequency and the formant frequency are detected from
an audio signal to be transmitted or an audio signal received, and an equalizer provided on the
transmitting side or the receiving side. The control means is controlled.
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[0014]
The invention described in claim 5 is a portable telephone apparatus for speech coding and
transmitting voice signals in a wide band, including a band limiting filter (for example, BPF 121
in FIG. 4) for band limiting and requiring band limiting. In such a case, a voice signal to be
transmitted is applied to the voice coding apparatus via a band limiting filter.
[0015]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention
will be described with reference to the drawings.
(First Embodiment) The first embodiment of the present invention is configured, for example, as
shown in FIG.
This example shows a PDC (Personal Digital Cellular) mobile phone.
[0016]
The mobile phone shown in FIG. 1 includes a microphone 10 for inputting a user's voice and an
audio interface 11 connected to a speaker 30 for outputting received voice, a variable attenuator
(ATT) 12, a voice coder / decoder 14, TDMA. Control circuit 16, modulator 18, frequency
synthesizer 19, power amplifier (PAMP) 20, antenna duplexer 22, transmission / reception
antenna 24, high frequency amplifier (HAMP) 26, demodulator 28, control circuit 32, display
unit 33 and keypad 34 The configuration is equipped with
[0017]
The analog voice signal output from the microphone 10 in response to the input voice from the
user is input to the voice coder / decoder 14 via the audio interface 11 and the ATT 12 and
converted into a digital signal.
The TDMA control circuit 16 performs processing such as error correction on the digital signal
from the voice coder / decoder 14, and then generates a TDMA transmission frame signal
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according to a predetermined time division multiple access (TDMA). .
The modulator 18 shapes the frame signal from the TDMA control circuit 16 and further
generates a π / 4 QPSK baseband signal, which is composed of carriers from the frequency
synthesizer 19 (two orthogonal carriers.
) Is modulated by π / 4 QPSK.
The modulated wave is amplified by the power amplifier 20 and transmitted from the
transmitting / receiving antenna 24 via the antenna duplexer 22.
[0018]
On the other hand, the π / 4 QPSK modulated wave from the base station is received by the
transmitting / receiving antenna 24 and applied to the high frequency amplifier 26 via the
antenna duplexer 22.
The modulated wave amplified by the high frequency amplifier 26 is π / 4 QPSK demodulated
by the demodulator 28.
The demodulator 28 is composed of carrier waves for demodulation generated by the frequency
synthesizer 19 (two orthogonal carrier waves. ) Is applied. Note that demodulation may be
performed after conversion into a signal of an intermediate frequency band, as necessary.
[0019]
The signal from the demodulator 28 is subjected to frame synchronization by the TDMA control
circuit 16 and subjected to processing such as demultiplexing, descrambling and error
correction. The output signal from the TDMA control circuit 16 is converted into an analog voice
signal by the voice coder / decoder 14. Then, the analog voice signal from the voice coder /
decoder 14 is supplied to the speaker 30 via the equalizer 48 and the audio interface 11, and the
voice is outputted from the speaker 30.
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5
[0020]
The display unit 33 and the key pad 34 are connected to the control circuit 32. The control
circuit 32 controls the TDMA control circuit 16 and the frequency synthesizer 19 based on an
input operation signal from the keypad 34 (for example, a signal corresponding to a transmission
operation), and also performs information on transmission and reception operations and other
necessary information. The information is displayed on the display unit 33.
[0021]
According to the above configuration, while the digital voice signal corresponding to the input
voice from the user is transmitted from the transmitting / receiving antenna 24 to the base
station, the portable telephone receives the digital voice signal from the base station, the digital
voice The signal is converted into an analog received audio signal, and an audio output based on
the received audio signal is made from the speaker 30. This enables the user to make a voice call
with the other party.
[0022]
The above-described mobile phone further includes a sound collection microphone 40, an input
interface 42, a noise detector 44, and an ATT control circuit 46. Sound (noise) around the mobile
phone is detected by the sound collection microphone 40, and a background sound signal
corresponding to the sound around the mobile telephone from the sound collection microphone
40 is supplied to the noise detector 44 through the input interface 42. Ru. The noise detector 44
measures the input noise frequency component and supplies the measurement result to the ATT
control circuit 46. The ATT control circuit 46 then controls the ATT 12 based on the noise level.
The microphone 10 and the microphone 40 may be the same.
[0023]
As a result, when the noise around the mobile telephone is large, a large audio signal output is
modulated and output, and when the noise around the mobile telephone is small, a small audio
signal output is modulated and output.
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[0024]
The ATT 12 may be a variable amplifier.
Also, the ATT 12 may be part of the audio interface 11 or the speech coder / decoder 14.
[0025]
As a result, the output sound volume adjustment according to the noise level is automatically
performed. Therefore, when the noise around the portable telephone is large, the sound signal
can be transmitted without being masked by the noise. As a result, on the receiving side, the
voice can be clearly heard regardless of the noise around the mobile phone on the transmitting
side. Second Embodiment FIG. 2 is a diagram showing a second embodiment. A noise canceller
51 and a noise canceller control circuit 52 are provided in FIG. 2 in place of the ATT and ATT
control circuit in FIG.
[0026]
The second embodiment includes a sound collection microphone 40, an input interface 42, a
noise canceller 51, and a noise canceller control circuit 52. Sound (noise) around the mobile
phone is detected by the sound collection microphone 40, and a background sound signal
corresponding to the sound around the mobile telephone from the sound collection microphone
40 is supplied to the noise detector 44 through the input interface 42. Ru. The noise detector 44
measures the input noise frequency component, and supplies the measurement result to the
noise canceller control circuit 52. Then, the noise canceller control circuit 52 controls the noise
canceller 51 based on the level of noise. The microphone 10 and the microphone 40 may be the
same.
[0027]
As a result, when the noise around the mobile telephone is large, the degree of cancellation of the
noise canceller 51 is intensified, and when the noise around the mobile telephone is small, the
degree of cancellation of the noise canceller 51 is weakened.
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[0028]
As a result, the degree of the noise canceller is automatically adjusted according to the noise
level, so that when the noise around the portable telephone is large, it is possible to transmit an
audio signal with reduced noise.
As a result, on the receiving side, even when the noise around the mobile phone on the
transmitting side is large, the user can clearly hear the voice. Third Embodiment FIG. 3 is a view
showing a third embodiment. The characteristics of the equalizer 48 provided on the receiving
side are adaptively controlled based on the audio signal.
[0029]
The third embodiment includes a sound collection microphone 40, an input interface 42, a pitch
/ formant detector 63, an equalizer control circuit 62, and an equalizer 48.
[0030]
The sound (noise) around the portable telephone is detected by the microphone 40, and the
sound signal from the microphone 40 is supplied to the pitch / formant detector 63 through the
input interface 42.
The pitch / formant detector 63 detects the pitch frequency and formant of the input speech
signal.
[0031]
As a result, the characteristic is changed to a sound that can be easily heard by the human ear,
and it is easy to listen to and transmit even a female "kinkin voice" or a male "boggling voice".
[0032]
The microphone 10 and the microphone 40 may be the same.
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[0033]
In addition, an equalizer that performs control based on the pitch frequency and formant of the
received audio signal may be provided on the receiving side.
Fourth Embodiment FIG. 4 is a diagram showing a fourth embodiment.
When band limitation is required, the speech signal to be transmitted is applied to the speech
coding apparatus through the band limitation filter.
[0034]
Audio signals are usually transmitted at 300 to 3400 Hz. However, there are cases where the
voice coder can not cope with transmission in the wide band region. For example, in the case of
PSI-CELP (Pitch Synchronous Innovation-CELP), which is a half rate speech coder using CELP
(Code-Excited Linear Prediction), the codebook is made in a band-limited form In the case of
transmitting in the wide band, it can not be handled.
[0035]
On the other hand, for example, in the case of encoding by CS-CELP (Conjugate Structure-CELP)
and transmission, it is possible to perform speech encoding while maintaining a wide band.
[0036]
Therefore, when the speech signal is encoded by PSI-CELP and transmitted for a speech signal in
a wide band, it is applied to the PSI-CELP encoder via a band-limiting filter, and the speech signal
is encoded by CS-CELP. In the case of transmitting in a coded format, it is encoded and
transmitted without band limitation.
[0037]
Specifically, as shown in FIG. 4, in the encoder in the speech coder / decoder, a BPF (Band Pass
Filter) is connected before the PSI-CELP 122, and a CS-CELP is connected to the BPF. , BPF is not
provided.
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[0038]
The voice signal in the wide band range applied to the input terminal 120 is band-limited to 300
to 3400 Hz by the BPF 121, encoded by the PSI-CELP 122, and output from the output terminal
130.
[0039]
On the other hand, when the speech signal is encoded by CS-CELP and transmitted, the speech
signal in the wide band applied to the input terminal 120 is encoded as it is by the PSI-CELP 122
and output from the output terminal 130.
[0040]
As a result, since the BPF 121 is provided in the front stage of the PSI-CELP 122, even if the
voice signal is transmitted in the wide band, only the CS-CELP side or the PSI-CELP side is
selected by the switch as needed. Then, the necessary encoder can be selected.
[0041]
As described above, according to the present invention, the cellular phone has improved the
output characteristics of the received voice signal regardless of the condition of noise derived
from ambient noise, the nature of the voice signal, and the presence or absence of the limitation
of the voice band. An apparatus can be provided.
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