JP3415529B2 - Wireless communication device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication device suitable for use in a wireless terminal for TDMA communication and this device, and more particularly to reducing burst noise generated by interference of transmission radio waves with a voice input circuit. Regarding the circuit.

[0002]

2. Description of the Related Art TDMA (Time Division)
In a wireless terminal that performs communication by a time division multiple access method called a Multipul Access method, since a radio wave is transmitted only for a fixed time within a TDMA cycle, this radio wave enters the voice input circuit of the wireless terminal and is amplified. There is a problem that this is heard as a burst noise of the TDMA cycle in the receiver on the receiving side.

As a method of reducing such burst noise, a method of reducing a noise component by inserting a high-pass filter into a voice line is generally used, but a desired voice signal component is also reduced at the same time. Therefore, the quality of the transmitted voice is affected.

As a countermeasure against this, for example, Japanese Patent Laid-Open No. 8-11
As disclosed in Japanese Laid-Open Patent No. 6315, a bandpass means that enlarges a frequency band in which noise is superimposed is output before noise is superimposed, and the bandpass means is increased in a latter stage after noise is superimposed. A technique for attenuating a signal in a frequency band where noise is superimposed has been proposed.

[0005]

However, the technique disclosed in the above publication has a problem that noise cannot be reduced when noise is superimposed on the input line from the microphone to the first stage. Furthermore, there is a problem that the circuit configuration becomes complicated because two band pass means are required.

An object of the present invention is to reduce burst noise without damaging a voice signal.

[0007]

To achieve SUMMARY OF THE INVENTION The above objects, in the wireless communication apparatus according to the present invention includes a voice input means for outputting a voice signal inputted voice is provided to the audio input means, the voice Interference noise generated by input means
From the voice input means
Interference noise component by adding to the output audio signal
To cancel the above, the electromotive force of opposite phase to the interference noise component
There is provided an antenna means for outputting a signal indicating the above, and a radio control means for processing the voice signal output from the voice input means and wirelessly transmitting it.

Here, the voice input means may be composed of a microphone and an amplifying means for amplifying a voice signal from the microphone, and the antenna means is connected in series to the microphone. Good.

Further, in another radio communication apparatus according to the present invention, a microphone for outputting a voice signal inputted voice, self
An antenna means for detecting an interference noise component in the vicinity of a microphone caused by a transmission radio wave generated from a device to generate an electromotive force, a voice signal obtained from the microphone, and an output signal of the antenna means are input. And differential control means for processing the output signal of the differential amplification means and wirelessly transmitting it.

In each wireless communication device, the wireless control means may wirelessly transmit by the TDMA method. Further, the antenna means may be provided near the microphone.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a wireless terminal as a wireless communication device according to an embodiment of the present invention and a TDM using this terminal.
It is a block diagram showing a wireless communication system according to the A system.

In the present embodiment, a built-in antenna 16 is provided in the voice input circuit composed of the microphone 15 and the transmission amplifier 17 in the wireless terminal 10, and the built-in antenna 16 detects an interference noise component near the microphone 15. Burst noise generated in the transmitted voice is reduced by generating an electromotive force having a phase opposite to that of the noise component and inputting it to the transmitting amplifier 17.

Next, a detailed description will be given with reference to FIG. In FIG. 1, reference numeral 10 denotes a wireless terminal, which includes a wireless unit 11, a control unit 12, a receiver 13, an antenna 14, a microphone 15, a built-in antenna 16, and a transmission amplifier 17. The wireless terminal 10 is wirelessly connected to the base station 20 and communicates with the telephone 30 of the other party via the exchanges 21 and 22.

In the wireless terminal 10, the voice signal from the microphone 15 is amplified by the transmission amplifier 17, and then the control unit 12
Is processed as a digital signal. The processed digital audio signal is supplied to the wireless unit 11, modulates a carrier wave of a predetermined frequency, and is transmitted from the antenna 14 at TDMA timing.

The built-in antenna 16 provided according to this embodiment is provided in a voice input circuit composed of a microphone 15 and a transmission amplifier 17. This built-in antenna 16
Detects an interference noise (burst noise) component generated by TDMA timing, generates a voltage having a phase opposite to the detected noise component, and inputs the voltage to the transmission amplifier 17.

In the transmission amplifier 17, the interference noise component to the voice input circuit and the antiphase interference noise component detected by the built-in antenna 16 are canceled, and only the voice signal from the microphone 15 is supplied to the control unit 12. And is output as a transmission voice.

Since the radio section 11 and the control section 12 are well known to those skilled in the art and are not directly related to the present invention, a detailed description of their construction will be omitted.

Next, the operation of the radio section 11 will be described with reference to the timing chart of FIG. Since it is the TDMA operation, the TDMA defined as shown in FIG.
Radio waves are transmitted only for a fixed time within the cycle. Therefore, the burst noise component of the interference component of the TDMA timing as shown in FIG. 2 (3) is superimposed on the voice input signal of FIG. 2 (2),
The waveform is such that burst noise is superimposed as shown in FIG.

On the other hand, the built-in antenna 16 is connected in series with the microphone 15 and is arranged near the microphone 15 so as to generate an electromotive force having a phase opposite to that of the interference component. Therefore, the interference component to the audio signal is canceled and the burst noise can be reduced.

Since the interference noise to the voice signal is canceled in this way, it is possible to reduce the burst noise generated in the receiver 30 on the partner side during a call.

In the above embodiment, the built-in antenna 16 is connected to the microphone 15 in series and grounded. However, as another embodiment, the transmission amplifier 17 is a differential amplifier and the built-in antenna is used. The electromotive force of 16 is in phase with the interference noise, and the output signal of the microphone 15 and the built-in antenna 1
Even if the output signal of 6 and the differential signal are input to the differential amplifier 17 as a differential input, the interference noise can be canceled.

[0022]

As described above, according to the present invention, by providing the built-in antenna in the voice input circuit, the interference noise can be reduced even when the noise is superimposed on the input line from the microphone to the first stage. It is possible to simplify the circuit configuration. Therefore, according to the present invention, burst noise can be reduced without always damaging the audio signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a wireless terminal as a wireless communication apparatus according to an embodiment of the present invention and a TDMA communication system using this terminal.

FIG. 2 is a timing chart showing the operation of the wireless unit of FIG.

[Explanation of symbols]

10 wireless terminals 11 radio section 12 Control unit 14 antenna 15 microphone 16 built-in antenna 17 Transmission amplifier

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04B 1/38-1/58 H04B 1/02-1/04

Claims (5)

(57) [Claims] 1. A voice input unit configured to include a microphone and an amplifying unit for amplifying a voice signal from the microphone, the voice input unit inputting voice and outputting the voice signal, and the voice input unit provided in the voice input unit. Occurrence
Generate an electromotive force of opposite phase to the interference noise component
By adding to the audio signal output from the input means,
The interference noise component for canceling the interference noise component
A wireless communication device comprising: an antenna unit that outputs a signal indicating an electromotive force of a reverse phase; and a wireless control unit that processes and wirelessly transmits a voice signal output from the voice input unit. 2. The wireless communication device according to claim 1, wherein the antenna means is connected to the microphone in series. 3. A microphone for inputting voice and outputting a voice signal, and detecting an interference noise component in the vicinity of the microphone, which is provided in the microphone and is caused by a transmission radio wave generated from the own device,
Antenna means for generating electromotive force, differential amplifying means to which a voice signal obtained from the microphone and an output signal of the antenna means are input, and a radio for processing the output signal of the differential amplifying means and wirelessly transmitting the processed signal. A wireless communication device comprising a control means. 4. The wireless communication device according to claim 1, wherein the wireless control means wirelessly transmits by a TDMA method. 5. The wireless communication device according to claim 1, wherein the antenna means is provided near the microphone.