JPH0983632A - Gsm system portable telephone system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of a hand-free adaptor and to reduce the cost by designing the hand-free adaptor to be connected to a DAI interface. SOLUTION: A hand-free adaptor 2 is connected to external connection terminals 19, 20 of a DAI interface so as to be interfaced by a digital signal. When the hand-free adaptor 2 is in use, a contact 12a of a switch 12 is selected, Furthermore, a contact 12b of the switch 12 is selected when a test device 3 for executing an acoustic test of an ear receiver 16 and a microphone 18 is connected to the external connection terminals 19, 20 to execute a test.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to GSM (Group Special) used in digital car telephone systems, which are widely used in Europe and Asia.
The present invention relates to a mobile type mobile phone device, and more particularly to a GSM type mobile phone device when an echo canceling type handsfree adapter is externally connected.

[0002]

2. Description of the Related Art GSM type mobile phone devices are available in Europe,
It is used as a mobile phone device in the digital car phone system that is widely used in Asia.
open Telecommunication S
standards Institute) Recommendation, GSM
It satisfies the standards of Recommendation.

Conventionally, this type of GSM mobile phone is often connected to an external hands-free adapter to make a hands-free call. FIG. 2 shows the configuration of a GSM mobile phone device to which a conventional hands-free adapter is connected.

In FIG. 2, a GSM type portable telephone device 4 is shown.
Is a downlink data signal 4 from the line side, which has been subjected to information compression processing.
A speech codec 41 which inputs 01 and decodes it into a downstream digital voice signal 402, compresses the upstream digital voice signal 405 and outputs it as an upstream data signal 406 to the line side, a downstream digital voice signal 402 and an upstream digital voice signal 405. External connection terminal 4
A switch 42 for switching to 9, 50, a D / A converter 43 for converting the downstream digital audio signal 402 into a downstream analog audio signal 403, and a downstream analog audio signal 403.
A receiver amplifier 45 that amplifies and outputs to the earpiece receiver 46, a microphone amplifier 47 that amplifies an upstream analog audio signal from a microphone, and an A that converts the amplified upstream analog audio signal 404 into an upstream digital audio signal 405.
And / D converter 44.

The hands-free adapter 5 is connected to the external connection terminals 51 and 52 for inputting and outputting the upstream and downstream analog voice signals 403 and 404 of the GSM mobile phone device 4 when performing a hands-free call.

The hands-free adapter 5 includes an A / D converter 52 for converting the downstream analog voice signal 403 into a digital voice signal, and a DSP for echoing the call voice from the speaker to the microphone at the stage of the digital voice signal.
(Digital Signal Processo
r), an echo canceller 53 for performing a suppression process, a D / A converter 55 for returning a downstream digital audio signal to an analog audio signal again, a speaker amplifier 57 for amplifying the analog audio signal, and a hands-free speaker. The downstream direction is configured.

Further in the upstream direction, a hands-free microphone 58 for generating an analog voice signal, a microphone amplifier 56 for amplifying this analog voice signal, and an echo canceller 5 are provided.
A / convert to digital audio signal for connection to 3
D converter 54 and D / for returning to analog audio signal again
It is composed of an A converter 51.

The test apparatus 6 is connected to the external connection terminals 49 and 50 provided on the digital analog interface (DAI). This test device 6 has a speaker,
A test of the acoustic characteristics of the analog part on the microphone side is performed. When this test is performed, the switch 42 is switched to the external connection terminals 49, 50 side. It is ET to have this function
It is specified in SI Recommendation.

For reference, an outline of the handsfree adapter will be described below. The hands-free adapter enables a user to have a conversation without holding the handset when making a voice call with the other party by using the handset. There is also a method of arranging the microphone and receiver near the face using a headset, but it is less flexible because it uses wires,
It is different from the hands-free adapter described here.

Although a specific method of realizing a hands-free adapter, howling is basically suppressed. The fact that the handset is not near the face means that the downstream voice is played loud through the speaker. Also, as for the upstream sound, there is a microphone far from the face, so when compared to the microphone of the handset,
You need to use a more sensitive microphone. As a result, the stability loss of the sound emitted from the speaker picked up by the microphone and transmitted to the other party is greatly deteriorated. Without any measures taken, the loop gain through going up and down exceeds 0 dB, and finally oscillation occurs. This is the howling phenomenon.

As a countermeasure against this, there are some hands-free circuits. One of them is a method of inserting a loss into an upstream or downstream circuit. If the upstream voice is large, a loss is added to the downstream voice, the downstream voice is reduced to suppress the loop gain, and conversely, if the downstream voice is large, a loss is added to the upstream voice. Reduces upstream voice and suppresses loop gain.

The second method is a method of performing canceling, which is a method of performing echo canceling using a DSP. Monitor both down and up audio,
When actually transmitting the upstream voice, the component added as an echo in the upstream voice is estimated and removed based on the component of the downstream voice. In this case, howling can be prevented because the specific frequency component does not increase. Moreover, since howling is prevented without reducing the sound of either the up or down stream, the product is highly marketable,
The use of the DSP is technically and costly higher than the former method.

Although either method has been implemented in a conventional mobile phone, in particular, in a digital mobile phone, voice is transmitted from one terminal to another because of the packet processing of voice as compared with the analog method. A few hundred meters
A signal delay occurs in units of seconds, and when the acoustic echo returns, the signal delay is large, which makes it easier for the listener to feel the sound.In particular, the acoustic coupling is great when talking with handsfree, so it is as if in the bathroom. Since there is a problem that the user feels as if he / she is talking, an echo canceller method that is highly effective against this problem is often used.

The object of the present invention relates to the use of this echo canceller type hands-free adapter in a specific system called GSM.

[0015]

As described above, in the conventional example, the hands-free adapter to be connected is interfaced with an analog signal. Therefore, after converting the analog signal into a digital signal in the hands-free adapter, the echo suppressor Suppression processing must be performed by the DSP, and then the analog signal is restored and input to the handsfree speaker. Since the analog audio signal is originally subjected to A / D conversion and D / A conversion in this manner, the sound quality of the hands-free adapter deteriorates due to S / N deterioration and the like. Further, since extra A / D conversion is performed, there is a problem that the hands-free adapter is large and expensive.

[0016]

A GSM mobile phone apparatus according to the present invention decodes an information-compressed downlink data signal from the line side into a downlink digital voice signal and compresses an upstream digital voice signal to obtain upstream data. A speech codec that is output as a signal to the line side, and D that converts the downlink digital voice signal into a downlink analog voice signal.
/ A converter, a receiver amplifier that amplifies the downstream analog audio signal and outputs it to an earpiece receiver, a microphone amplifier that amplifies the upstream analog audio signal from the microphone, and the amplified upstream analog audio signal to the upstream digital audio signal. GS with A / D converter for conversion
In the M type portable telephone device, an external connection terminal is provided in the DAI interface between the speech codec and the D / A converter and the A / D converter, and an echo canceling type hands is provided in which the external connection terminal is interfaced with a digital audio signal. When a free adapter is connected, the digital voice signal on the handsfree adapter side is input / output to / from the speech codec side instead of the downlink digital voice signal and the upstream digital voice signal, and the sound on the transmitting / receiving side is input to the external terminal. When a test device for measuring characteristics and the like is connected, a test signal on the side of the test device is input / output to / from the D / A converter and the A / D converter side instead of the downlink digital audio signal and the uplink digital audio signal. Switch to change each Eteiru.

[0017]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment. That is, it shows a configuration in which the free hands adapter 2 or the test device 3 is connected to the GSM mobile phone device 1.

The GSM mobile phone unit decodes the information-compressed downlink data signal 101 from the line side into a downlink digital voice signal 102 and compresses the upstream digital voice signal 105 to the line side as an upstream data signal 106. Speech codec 11 to output and down,
A switch 12 for switching the upstream digital audio signals 102 and 105 in three directions, external connection terminals 19 and 20 of the DAI interface, and D for converting the downstream digital audio signal 102 into the downstream analog audio signal 103.
A / A converter 13, a receiver amplifier 15 that amplifies the downstream analog audio signal 103 and outputs it to the earpiece receiver 16, a microphone amplifier 17 that amplifies the upstream analog audio signal from the microphone 18, and an amplified upstream analog audio signal 104. It is composed of an A / D converter 14 for converting the upstream digital audio signal 105.

A hands-free adapter 2 connected to the DAI external connection terminals 19 and 20 of the GSM mobile phone device 1.
Is an interface with a digital voice signal, and an echo canceling 11 that suppresses an echo that a call voice circulates from a speaker to a microphone with respect to the digital voice signal, and a downlink digital voice signal that has passed through the echo canceller 11 is converted into an analog voice signal. D / A to convert
Converter 22 and speaker amplifier 2 that amplifies this analog audio signal and outputs it to hands-free speaker 26
4, a hands-free microphone 27 that generates an analog audio signal in the up direction, a microphone amplifier 25 that amplifies this analog audio signal, and the amplified analog audio signal is converted into an upstream digital audio signal and output to the echo canceller 21. It is composed of an A / D converter 23.

During the test, the DAI external connection terminal 19,
The test device 3 connected to the device 20 tests the acoustic characteristics of the analog part of the speaker and the microphone of the GSM mobile phone device 1.

In the following configuration, when the GSM type mobile phone device itself is used, although the switch 12 is in the state shown in the drawing, the hands-free adapter 2 is connected to the external connection terminals 19 and 20 to be used hands-free. In this case, the switch 12 switches the contact 12a to connect the hands-free adapter 2 to the speech codec 11 side. When the test apparatus 3 is connected and used, the switch 12 switches the contact 12b to connect the test apparatus 3 to the A / D and D / A converter side.

[0022]

As described above, in the GSM portable telephone device of the present invention, a hands-free adapter can be connected to the DAI external connection terminal, and a voice signal is interfaced with a digital signal. Can be entered directly into the echo suppressor. Therefore, A / D and D / A converters are not required as compared with the case of interfacing with analog signals. Further, since it is interfaced with a digital signal, it is less likely to be affected by noise, so that it is effective in improving the sound quality of the hands-free adapter, improving the echo canceling characteristics, and reducing the cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional example.

[Explanation of symbols]

 1 GSM mobile phone device 2 Hands-free adapter 3 Measuring instrument 11 Speech codec 12 Switch 13 D / A converter 14 A / D converter 15 Receiver amplifier 16 Earpiece receiver 17 Microphone amplifier 18 Microphone 19 DAI external connection terminal 20 DAI external connection terminal 21 Echo Canceller 22 D / A Converter 23 A / D Converter 24 Speaker Amplifier 25 Microphone Amplifier 26 Handsfree Speaker 27 Handsfree Microphone 101 Downstream Data Signal 102 Downstream Digital Audio Signal 103 Downstream Analog Voice Signal 104 Upstream Analog Voice Signal 105 Upstream Digital Voice Signal 106 Upstream data signal

Claims (1)

[Claims] 1. A speech codec for decoding a downlink data signal, which has been subjected to information compression processing from the line side, into a downlink digital voice signal and for compressing the information of the upstream digital voice signal and outputting it as an upstream data signal to the line side, and the downlink digital signal. A D / A converter for converting an audio signal into a downstream analog audio signal, a receiver amplifier for amplifying the downstream analog audio signal and outputting it to an earpiece receiver, a microphone amplifier for amplifying an upstream analog audio signal from a microphone, and an amplifier And an A / D converter for converting the upstream analog audio signal into the upstream digital audio signal
In the M type mobile phone device, the DAI between the speech codec and the D / A converter and the A / D conversion.
When an echo canceling hands-free adapter that interfaces with a digital audio signal is connected to the interface and an external connection terminal is connected to the interface, the digital audio signal on the hands-free adapter side is used as the downlink digital audio signal and the uplink digital audio signal. When a test device for inputting / outputting to / from the speech codec side instead of the digital voice signal and connecting to the external terminal to measure the acoustic characteristics of the transmitting / receiving side is connected, the test signal of the test device side is used as the downlink digital voice signal. And the D / A converter and the A instead of the upstream digital voice signal
A GSM mobile phone device, which is equipped with a switch for switching between input and output to the / D converter side.