JP2806869B2 - Voice codec timing control method and digital mobile radio using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio codec timing control method and a digital mobile radio using the same, and more particularly, to a MODEM for performing digital modulation / demodulation of digital signal data, synchronization detection, and synchronization timing control for wireless communication. And a voice codec for performing encoding and decoding between a digital voice signal input / output as voice information and digital voice data processed by the MODEM unit, and a voice codec other than the digital voice data processed by the MODEM unit. A digital mobile radio device having a channel codec unit for encoding and decoding digital signal data and performing operation timing control of the audio codec based on synchronization timing control information from the MODEM unit, and an operation timing of the audio codec Control method.

[0002]

2. Description of the Related Art A digital mobile communication system, particularly a digital mobile radio, which is one of mobile communication devices realized by a digital MCA (multi-channel access) radio system using a time division multiple access (TDMA) system, is shown in FIG. The configuration is as shown in FIG. In FIG. 3, a radio unit 2 transmits and receives an encoded digital signal to and from a base station radio unit (not shown) by radio via an antenna 1. The MODEM unit 3 modulates digital signal data to be transmitted through the radio unit 2 and demodulates the received digital signal. The MODEM unit 3 calculates a correlation value for a synchronization symbol, detects a synchronization symbol position, detects a synchronization symbol position, and performs frame synchronization. And a synchronization timing control unit 33 for controlling transmission timing and reception timing based on the detected synchronization symbol position.
The channel codec unit 4 includes an encoding unit 41 that encodes digital signal data other than digital audio data to be transmitted through the MODEM unit 3, and a decoding unit 4 that decodes received digital signal data other than digital audio data.
2 and a control unit 43 for controlling the operation timing of the audio codec 5. The voice codec 5 transmits a PCM (Pulse) to be transmitted through the channel codec unit 4.
It has an encoding unit 51 for encoding a Code Modulation audio signal and converting it to digital audio data, and a decoding unit 52 for decoding the received digital audio data and converting it to a PCM audio signal. PCM codec 6
Is an analog-to-digital converter 61 that converts an analog audio signal from a microphone (transmitter) 9 into a PCM audio signal and outputs the PCM audio signal to the audio codec 5, and a PCM audio signal from the audio codec 5 to the speaker (receiver) 8. And a digital-to-analog conversion unit 62 for converting the signal into an analog audio signal to be output. The amplifier 7 amplifies the analog audio signal supplied from the PCM codec 6, supplies the signal to the speaker 8, and outputs the signal as audio. On the other hand, amplifier 1
0 amplifies the analog audio signal input from the microphone 9 and supplies it to the PCM codec 6. An MCPU (central control unit) 11 controls the operation of each unit according to the operation of the operation keys of the operation unit 12, and displays various operation states on a display unit 13.
To be displayed. The MODEM unit 3 and the channel codec unit 4 are realized using a digital signal processor (DSP) controlled by software.
Similarly, the MCPU 11 is realized using a general-purpose CPU chip controlled by software. The above components are provided in one housing of the digital mobile radio.

The MODEM unit 3 of this digital mobile radio device
The operation of the channel codec unit 4 will be described with reference to FIGS. In the synchronization detection operation, the reception signal of the reception channel is fetched from the radio unit 2 by the MODEM unit 3 (step S401 in FIG. 4), and a baseband conversion (step S402) is performed. For the received data, the correlation value calculation is performed while shifting the correlation calculation window in the sampling unit of the symbol data (steps S403 to S407), and a point having a maximum correlation value exceeding a preset threshold is detected as a synchronization symbol position. Then, frame synchronization is established by regarding this detection point as a reception timing position (step S404).
In the synchronization timing control operation, the symbol of the received signal obtained when detecting the reception timing position and the amount of deviation of the sampling unit are used as correction amounts (step S411), and are used for the next reception. An operation for correcting the position is performed (steps S412 and S41).
3). Further, using the correction amount, the operation timing control such as the acquisition of audio data and the output permission for the audio codec 5 in the channel codec unit 4 is performed by the MC.
It is executed when instructed by the PU 11, that is, when information indicating that the telephone is in a call operation state is received. Basically, AGC
When the control and the AFC control are normally performed, the detection of the synchronization symbol and the reception timing point thereof can be almost specified by performing the processing of the above-described MODEM unit 3, and the correction thereof is also performed on the symbol and the sampling timing thereof. Therefore, the operation timing control of the audio codec 5 to be performed together is also performed using the correction amount as it is (steps S501 to S504 in FIG. 5).

[0004]

In a digital communication system in a wired system or a fixed communication system, since the communication line quality is relatively stable, synchronization with a transmission sequence is required for synchronization detection and synchronization timing control. Is easy to take. However, in a digital mobile communication system, stable communication line quality is not always ensured. Therefore, in performing synchronization detection and synchronization timing control, a sudden increase in a received signal due to factors such as multipath, fading, and delay dispersion. Changes occur,
It is difficult to establish synchronization, that is, the detection position of the synchronization symbol frequently fluctuates, and as a result, the reception timing position is frequently corrected. In addition, when the synchronization symbol is determined by performing the correlation value calculation, in the above-described situation, a malfunction occurs in which the correlation value for a different symbol having characteristics similar to the actual synchronization symbol is regarded as valid. As a result, a position different from the original position is regarded as the reception timing position. Therefore, like the conventional digital mobile communication device described above, M
The reception timing control processing of the audio codec using the correction amount of the reception timing obtained by the synchronization detection processing of the ODEM unit also causes a malfunction, thereby causing a problem of deterioration of the audio quality such as cutoff of sound and generation of noise. That is, in the above-described situation, the correlation value calculation for the synchronization symbol, the symbol obtained from the symbol point showing the maximum correlation value exceeding the preset threshold value, and the audio codec using the reception timing correction amount of the sampling unit are used. The operation timing control alone cannot prevent the erroneous operation due to the fluctuation of the reception timing position and the erroneous detection of the synchronization symbol.

[0005]

A voice codec timing control method according to the present invention includes a MODEM unit for performing digital modulation / demodulation of digital signal data, synchronization detection, and synchronization timing control for wireless communication, and input / output as voice information. Audio codec for encoding and decoding between PCM audio signals and digital audio data processed by the MODEM unit, and encoding and decoding of digital signal data other than the digital audio data processed by the MODEM unit And a channel codec unit for controlling the operation timing of the voice codec based on the synchronization timing control information from the MODEM unit. During the detection operation,
A step of generating synchronization detection information indicating a state of either synchronization detection or non-synchronization detection, and adding the synchronization detection information to the synchronization timing control information indicating a correction amount of the synchronization timing calculated at the same time, and recording a history of the synchronization timing control information Calculating the cumulative value of the synchronization timing correction amount and setting the control amount as a required control amount; and, during the operation timing control of the audio codec of the channel codec unit, a history of synchronization detection or synchronization non-detection indicated by the synchronization detection information. Switching a ratio for obtaining a correction amount of the operation timing of the voice codec from the required control amount according to a situation; and controlling only the control amount corresponding to a specified ratio among the required control amounts to the operation timing of the voice codec. And a step of subtracting from the required control amount by this correction amount. .

In the above-mentioned step, a step of counting the number of consecutive times when the synchronization detection information indicates a state of not detecting synchronization and a number of consecutive times when indicating the state of detection of synchronization are respectively performed; If the number of consecutive synchronization detection information exceeds a first threshold value set in advance, the required control amount is used as a ratio for obtaining the correction amount of the operation timing of the audio codec from the required control amount. A step of designating a first ratio as a correction amount of the operation timing; and, when the number of consecutive synchronization detection information indicating the state of the synchronization detection exceeds a second threshold set in advance, the first ratio is set as the ratio. Specifying a second ratio that is a value obtained by dividing the ratio by a preset number; Maintaining the designation of the first ratio or the second ratio if the number of consecutive synchronization detection information indicating the state of the synchronization detection does not exceed the first threshold and the second threshold, respectively. be able to.

A digital mobile radio device according to the present invention comprises a MODEM unit for performing digital modulation / demodulation of digital signal data for radio communication, synchronization detection, and synchronization timing control, a digital audio signal input / output as audio information, and the M signal.
An audio codec for encoding and decoding between digital audio data processed by the ODEM unit;
A channel codec unit for encoding and decoding digital signal data other than the digital audio data processed by the M unit and performing operation timing control of the audio codec based on the synchronization timing control information from the MODEM unit. In the digital mobile radio, wherein the MODEM unit and the channel codec unit are configured by a digital signal processor controlled by software, the MODEM unit performs a synchronization detection process on received data,
Synchronization detection information indicating either a synchronization detection state or a non-synchronization detection state is generated and added to the synchronization timing control information indicating the correction amount of the synchronization timing calculated at the same time. Means for obtaining a cumulative value of the correction amount of the synchronization timing for each time and storing it as a required control amount; means for counting the number of consecutive times when the synchronization detection information indicates a state where synchronization is not detected; Means for counting the number of consecutive times in the case of indicating the state of detection, means for presetting a first threshold value and a second threshold value to be compared with the number of consecutive times, and an operation of the voice codec based on the required control amount Means for presetting a first ratio for obtaining a timing correction amount and a second ratio which is a predetermined fraction of the first ratio. When the number of consecutive times of the synchronization detection information indicating the state of unsynchronization exceeds the first threshold, the first ratio is used as the required control amount as the correction amount of the operation timing of the audio codec. If the number of consecutive synchronization detection information indicating the state of the synchronization detection exceeds the second threshold, the second ratio is specified; otherwise, the first ratio or the second ratio is specified. Is maintained as it is, and only the control amount corresponding to a specified ratio among the required control amounts during the operation timing control of the audio codec is used as the correction amount of the operation timing of the audio codec. Has a configuration to reduce from the amount.

According to the present invention, it is possible to easily control the operation timing of the voice codec easily by changing the software of the digital signal processor (DSP) mounted as a channel codec in the digital mobile radio. Can be. That is, in the operation timing control of the audio codec using the correction amount of the symbol unit and the sampling unit performed by the channel codec unit, the information at the time of the synchronization detection operation performed by the MODEM unit is “synchronization detection (synchronization establishment)”. ”And“ synchronization not detected (synchronization not established) ”are also added as information for the control, and the output of the correction amount in the symbol unit and the sampling timing unit is switched according to the synchronization detection state, thereby changing the reception state. The operation timing control of the corresponding audio codec can be optimally performed. This makes it possible to optimize the operation timing control of the audio codec,
By using and using the conventional information for the information necessary for the control, it is possible to suppress the need to add a new hardware / software interface, and realize only by changing the software.

[0009]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 is a block diagram of a digital mobile radio device to which the present invention is applied. The basic configuration is the same as that of the prior art, but the operations of the MODEM unit 3 and the channel codec unit 4 are partially different. FIG. 1 shows the M
FIG. 2 is a flowchart showing an operation of the ODEM unit 3, and FIG. 2 is a flowchart showing an operation of the channel codec unit 4, and shows only a part related to the present invention. A detailed description of the same parts as those in the conventional technique will be omitted.

The digital mobile radio device includes a radio unit 2 for transmitting and receiving a digital signal coded wirelessly through an antenna 1, a digital modulation / demodulation unit 31 for modulating / demodulating a digital signal transmitted / received via the radio unit 2, and synchronization by correlation value calculation. A MODE having a synchronization detection unit 32 for detecting a symbol position and performing frame synchronization and a synchronization timing control unit 33 for controlling transmission / reception timing based on the synchronization symbol position
An M unit 3; an encoding unit 41 and a decoding unit 42 for encoding and decoding digital signal data other than digital audio data transmitted and received through the MODEM unit 3; And an audio codec 5 having an encoding unit 51 and a decoding unit 52 for performing mutual conversion (encoding and decoding) between PCM audio signals of digital audio data transmitted and received through the channel codec unit 4 And a PCM codec 6 having a digital / analog conversion unit 62 and an analog / digital conversion unit 61 for mutually converting between a PCM audio signal transmitted and received through the audio codec 5 and an analog audio signal, and an analog audio signal from the PCM codec 6 Is amplified and output as sound from the speaker 8 An amplifier 7 to an amplifier 10 which supplies the PCM CODEC 6 amplifies the analog audio signal from the microphone 9, the operation section display unit 13 the various operating conditions and controls the operation of the respective units in accordance with the operation of the operation keys 12
And an MCPU (central control unit) 11 for displaying the information. The MODEM unit 3 and the channel codec unit 4 are realized using a digital signal processor (DSP) controlled by software. Also,
Similarly, the MCPU 11 is realized using a general-purpose CPU chip controlled by software.

The difference between the digital mobile radio of the present invention and that of the prior art is that the MODEM unit 3 performs a process of detecting the synchronization of the received data and performs a synchronization detection indicating either a synchronization detection or a non-synchronization detection. The information is generated, added to the synchronization timing control information indicating the synchronization timing correction amount calculated at the same time, and output to the channel codec unit 4.
Means for obtaining the cumulative value of the correction amount of the synchronization timing for each synchronization timing control information from the section 3 and storing the same as a required control amount; means for counting the number of consecutive times when the synchronization detection information indicates a state where synchronization is not detected; Means for counting the number of consecutive times when the synchronization detection information indicates the state of synchronous detection, means for presetting a first threshold value and a second threshold value to be compared with the number of consecutive times, Means for presetting a first ratio for obtaining the correction amount of the operation timing of the codec 5 and a second ratio which is a predetermined fraction of the first ratio. If the number of consecutive times of the synchronization detection information exceeds the first threshold value, the first control unit designates the first control as the correction amount of the operation timing of the audio codec 5 without changing the required control amount. If the number of successive information exceeds a second threshold value specifying a second ratio, otherwise the first
Is maintained as it is, and only the control amount corresponding to the specified ratio among the required control amounts during the operation timing control of the audio codec 5 is used as the correction amount of the operation timing of the audio codec 5, and this correction is performed. The point is that the required control amount is reduced by the amount.

Next, the operation will be described.

The MODEM unit 3 of the digital MCA mobile radio performs baseband conversion of a digital reception data sequence fetched from the radio unit 2 at the time of reception after channel designation (steps S101 and S102 in FIG. 1) as a synchronization detection operation.
In order to detect a synchronization symbol (for example, a three-symbol configuration) that is known information included in advance, the sampling unit of the symbol data is used for data (for example, about eight symbols) near the received synchronization symbol. The correlation value is calculated while shifting the correlation calculation window (for example, 24 samplings per symbol) (steps S103 to S106), and a point having a maximum correlation value exceeding a preset threshold is detected as a synchronization symbol position. Then, frame synchronization is established by regarding this detection point as a reception timing position (step S104). At the time of this threshold determination, synchronization detection information indicating either “synchronization detection (synchronization established)” or “synchronization not detected (synchronization not established)” can be obtained (step S107 or step S1).
11). As the synchronization timing (reception timing) control operation, the shift amount of the symbol position of the received signal (the shift amount of the sampling unit) obtained when the reception timing position is detected in the process of step S105 is corrected (control). Amount) (step S112), and an operation of correcting the next reception position is performed using this (step S113). If no synchronization is detected, the synchronization symbol position is unknown, so the correction amount (control amount) is set to “0” for the time being.
And Alternatively, the correction amount (control amount) of the synchronization timing of an arbitrary value can be set according to an instruction from the MCPU 11. The MODEM unit 3 converts the reception timing correction amount of the symbol sampling unit obtained up to this point (the sampling number (24) or more for one symbol can be specified) and the corresponding synchronization detection information into the channel codec unit. 4 (step S114). Thereafter, the above-described step S101 is performed for each frame of the received data.
To S114 are repeated. When the state where the synchronization is not detected is repeated several times, the channel designation of the wireless unit 2 is switched by the instruction of the MCPU 11, and the above processing (step S10
1 to S114) are repeated.

In the channel codec section 4, the MODEM
The reception timing correction amount (control amount) fetched from the unit 3,
And the audio codec 5 using the synchronization detection information
Prior to performing operation timing control such as fetching of audio data and output permission, it is determined whether or not an instruction has been given from the MCPU 11 at that time, that is, whether or not there is information that the user is in a call state. As a result, if it is in a call state, the reception status is determined based on the synchronization detection information, and the MODEM unit 3 determines the reception status according to the frequency of occurrence of the synchronization detection (synchronization establishment) state and the synchronization non-detection (synchronization not established) state. The ratio of the operation timing correction amount of the audio codec to the reception timing correction amount is switched. That is, the channel codec unit 4 sequentially takes in the reception timing control amount and the synchronization detection information each time the MODEM unit 3 outputs the synchronization detection information.
The sum is sequentially accumulated, and +/− settlement is performed including the operation timing correction amount to the audio codec 5 described later, and is set as a required timing control amount which is a correction amount required at that time (steps S201 to S202 in FIG. 2). ), The history of the synchronization detection information is stored over the past using a synchronization detection counter and a synchronization non-detection counter (not shown). The synchronization detection counter is incremented by one each time the content of the synchronization detection information indicates synchronization detection, and is cleared when synchronization has not been detected. The synchronization non-detection counter is incremented by one each time the content of the synchronization detection information indicates that synchronization has not been detected, and is cleared when synchronization has been detected. Each time the channel codec unit 4 receives the synchronization detection information from the MODEM unit 3 (step S203),
The synchronization detection counter and the synchronization non-detection counter are updated and cleared according to the contents (steps S204, S21).
1). The count value of the synchronization non-detection counter (the number of consecutive times of synchronization non-detection) is set to a first threshold (for example,
5) is determined (step S212). If it exceeds, it is recognized that synchronization is extremely unstable, and the conversion ratio for obtaining the operation timing correction amount (control amount) of the audio codec 5 from the above-described required timing control amount. Is selected in advance, that is, "1/1", and the required timing control amount is directly used as the operation timing correction amount of the audio codec 5 (step S213). Similarly,
It is determined whether or not the count value of the synchronization detection counter (the number of consecutive synchronization detections) exceeds a preset second threshold value (for example, 5) (step S205). If it exceeds, it is recognized that synchronization is extremely stable. From the required timing control amount, the operation timing correction amount (control amount) of the audio codec 5
A second ratio, for example, "1/8" set in advance is selected as a conversion ratio for calculating the required timing control amount, and 1/8 of the required timing control amount is set as the operation timing correction amount of the audio codec 5 (step S206). When the count value of the synchronization non-detection counter is equal to or less than the first threshold value and when the count value of the synchronization detection counter is equal to or less than the second threshold value, the conversion ratio for obtaining the operation timing correction amount of the audio codec 5 from the required timing control amount. Keep the value selected last time. Next, if the channel codec unit 4 receives a control instruction for notifying the communication state from the MCPU 11 (step S22)
1) The operation timing correction amount obtained according to the conversion ratio determined at this time is transmitted to the audio codec 5, and the operation timing correction control is performed (step S222), and the operation transmitted to the audio codec 5 is performed. The control amount of the reception timing from the MODEM unit 3 is accumulated and subtracted from the adjusted required timing control amount by the amount of the timing correction (step S223).

In summary, in the digital mobile radio of the present embodiment, when the AGC control and the AFC control are normally performed normally, the above-described processing of the MODEM unit 3 is performed to obtain the synchronization symbol. The detection and the reception timing point can be almost specified, and the correction can be performed in units of symbol sampling timing. Therefore, when the synchronization detection information indicating “synchronization detection (synchronization establishment)” is continuously obtained, In this case, the reception situation is relatively stable, and the reception timing correction in this case does not need to be largely moved. Therefore, the received symbol sampling unit “1”
The correction amount of “/ 8” is set as the reception timing correction amount, and the operation of the audio codec 5 is controlled with this value. That is, the response of the operation control to the audio codec 5 is delayed (it takes eight times as long as the normal time to complete the response). However, when "synchronization not detected (synchronization not established)" information is continuously obtained, the reception situation is unstable, and the reception timing correction in this case follows the reception situation. We need to change it. Therefore, the “correction amount of the received symbol (unit of sampling timing)” is set as the reception timing correction amount, and the operation of the audio codec 5 is controlled with this value. That is, the response of the operation control of the audio codec 5 is made faster. When the “synchronization detected (synchronization established)” state and the “synchronization undetected (synchronization unestablished)” state do not last for a long time and are frequently switched, the calculation standard of the reception timing correction amount is not changed and remains as before.
By performing such control, the response speed of the control of the operation of the voice codec 5, which has been conventionally controlled simply in synchronization with the synchronization detection state, is adjusted to obtain multipath, fading, delay dispersion, and the like. Even if the received signal suddenly fluctuates due to factors, it is possible to prevent the reception timing from fluttering and malfunction due to false detection of the synchronization symbol, and as a result, the operation timing control of the voice codec according to the reception situation is optimized. In this way, it is possible to suppress the deterioration of the voice quality such as the interruption of the sound or the generation of noise due to the malfunction.

The number of times "synchronous detection (synchronization established)" is obtained continuously or the number of times "synchronous non-detection (synchronization not established)" obtained continuously is determined. The setting of the first and second threshold values and the first and second conversion ratios for obtaining the operation timing correction amount of the audio codec 5 from the timing correction amount of the MODEM unit 3 are arbitrary values beforehand in software processing. Can be set. Alternatively, by partially changing the software processing configuring the operation of the MCPU 11, the operation unit 1
It is also possible to make settings from 2 and to confirm the current setting status on the display unit 13.

[0017]

As described above, according to the present invention, in a digital mobile radio, at the time of a synchronization detection operation of a MODEM section, synchronization detection information indicating either a synchronization detection state or a synchronization non-detection state is generated. At the same time, it is added to the synchronization timing control information indicating the correction amount of the synchronization timing, the history is recorded, the accumulated value of the correction amount is obtained, and the required control amount is obtained. The ratio for obtaining the correction amount of the operation timing of the audio codec from the required control amount is switched according to the history state of the synchronization detection or the synchronization non-detection indicated by the information, and only the control amount corresponding to the specified ratio of the required control amount is switched. Is used as the correction amount of the operation timing of the audio codec, so that the audio codec according to the reception condition at that time can be obtained only when necessary. By outputting the operation timing correction value, the optimal operation timing control of the audio codec can be performed even when the reception condition is deteriorated due to fading or the like. Deterioration can be suppressed.

When the MODME section and the channel codec section are constituted by a digital signal processor (DSP) controlled by software, only the software processing section is changed so as to perform the above-mentioned operation, and the audio processing is performed. For the procedure for optimally controlling the operation timing of the codec and the information required for the control, the existing information can be used and used, and the voice can be reduced while suppressing the need to add a new hardware / software interface. The effect of performing the optimal operation timing control of the codec can be obtained.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an operation of a MODEM unit according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of a channel codec unit according to one embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a digital MCA mobile radio device to which the present invention is applied.

FIG. 4 is a flowchart showing the operation of a MODEM unit according to the related art.

FIG. 5 is a flowchart showing an operation of a channel codec section in the conventional technique.

[Explanation of symbols]

 2 Radio unit 3 MODEM unit 4 Channel codec unit 5 Audio codec 6 PCM codec 11 MCPU

Continuation of front page (58) Fields investigated (Int.Cl. ⁶ , DB name) H04B 7/26 H04L 7/00 H03M 7/00

Claims (3)

(57) [Claims] 1. A MODEM unit for performing digital modulation / demodulation, synchronization detection, and synchronization timing control of digital signal data for wireless communication, and a PC that inputs and outputs audio information.
An audio codec for performing encoding and decoding between the M audio signal and the digital audio data processed by the MODEM unit; and encoding and decoding of digital signal data other than the digital audio data processed by the MODEM unit. A method for controlling the operation timing of the voice codec in a digital mobile radio having a channel codec unit for controlling the operation timing of the voice codec based on the synchronization timing control information from the MODEM unit. At the time of operation, synchronization detection information indicating either the state of synchronization detection or synchronization non-detection is generated, and added to the synchronization timing control information indicating the correction amount of the synchronization timing calculated at the same time, and the history of the synchronization timing control information is recorded. Recording and accumulating the correction amount of the synchronization timing When the operation timing of the audio codec of the channel codec unit is controlled, the operation of the audio codec is performed from the required control amount in accordance with the history of synchronization detection or synchronization non-detection indicated by the synchronization detection information. A ratio for obtaining a timing correction amount is switched, and only a control amount corresponding to a specified ratio among the required control amounts is set as a correction amount of the operation timing of the audio codec, and is subtracted from the required control amount by the correction amount. A speech codec timing control method characterized by the above-mentioned. 2. The method according to claim 1, wherein the number of continuations when the synchronization detection information indicates a non-synchronization detection state and the number of continuations when the synchronization detection information indicates a synchronization detection state are counted. When the number of times exceeds a first threshold set in advance, the required control amount is used as a ratio for obtaining the correction amount of the operation timing of the audio codec from the required control amount, and the correction amount of the operation timing of the audio codec is used as it is. When the number of consecutive synchronization detection information indicating the state of the synchronization detection exceeds a second threshold set in advance, the first ratio is set as the ratio by a predetermined number. A second ratio, which is a divided value, is designated, and the number of consecutive times of synchronization detection information indicating the state of not detecting synchronization and the number of consecutive times of synchronization detection information indicating the state of synchronization detection Are respectively the first threshold value and the second threshold value.
The first ratio or the second ratio designation is maintained if the threshold value is not exceeded.
The described speech codec timing control method. 3. A MODEM unit for performing digital modulation / demodulation, synchronization detection, and synchronization timing control of digital signal data for wireless communication, a digital audio signal input / output as audio information, and a digital audio signal processed by the MODEM unit. An audio codec for performing encoding and decoding between data, and encoding and decoding of digital signal data other than digital audio data processed by the MODEM unit, and based on synchronization timing control information from the MODEM unit. A digital codec having a channel codec unit for controlling operation timing of the voice codec, wherein the MODEM unit and the channel codec unit are configured by a digital signal processor controlled by software; Synchronization detection processing of received data Generating synchronization detection information indicating a state of either synchronization detection or non-synchronization detection, and adding the synchronization detection information to the synchronization timing control information indicating the correction amount of the synchronization timing calculated at the same time; Means for obtaining an accumulated value of the correction amount of the synchronization timing for each control information and storing the same as a required control amount; means for counting the number of consecutive times when the synchronization detection information indicates a state where synchronization is not detected; Means for counting the number of consecutive times when indicates the state of synchronization detection, means for presetting a first threshold value and a second threshold value to be compared with the number of consecutive times, and the audio codec based on the required control amount. A method for setting a first ratio for obtaining the correction amount of the operation timing and a second ratio which is a predetermined fraction of the first ratio in advance. And when the number of consecutive times of the synchronization detection information indicating the synchronization undetected state exceeds the first threshold, the required control amount is directly used as the correction amount of the operation timing of the audio codec. The second ratio is specified when the number of consecutive times of the synchronization detection information indicating the state of the synchronization detection exceeds the second threshold, and in other cases, the first ratio or the second ratio is specified. In the operation timing control of the audio codec, only the control amount of the specified ratio among the required control amounts is used as the correction amount of the operation timing of the audio codec, and the operation amount of the audio codec is adjusted by the correction amount. A digital mobile wireless device, wherein the required control amount is reduced.