JPH06164479A - Portable telephone set - Google Patents

Abstract

PURPOSE:To provide a digital portable telephone set reproducing a clear sound without deteriorating tone from the beginning. CONSTITUTION:At the time of communication, encoding voice data encoded by a voice encoder 2 with the internal state information of the encoder 2 at the time of encoding a leading frame added are stored in a memory M. Encoding voice data from the opposite party decoded by a high frequency section 3 are decoded by a voice decoder 4 and stored in the memory 3 with the internal state information of the voice decoder 4 at the time of decoding the leading frame added. In the stored two-system encoding voice data, each leading frame is decoded with the use of the stored internal state information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital portable telephone device having a voice encoding means such as a digital cellular system or a digital cordless system.

[0002]

2. Description of the Related Art In the conventional digital portable telephone apparatus, as shown in the block diagram of the circuit configuration in FIG. 4, the voice input from the microphone MC is quantized by the A / D conversion circuit 31 on the transmitting side. Discretized digital voice data is obtained, and further, by the voice encoder 32, information source coding (voice compression) and communication channel coding (error correction coding).
For example, in the case of the full rate digital cellular system, it is converted into encoded voice data having an encoding rate of 11.2 kilobits per second, modulated by the high frequency unit 33 into a radio frequency and transmitted to the base station. On the other hand, on the receiving side,
The modulated signal coming from the base station is demodulated by the high frequency unit 33 and input to the speech decoder 34 as encoded speech data. The voice decoder 34 performs inverse conversion of the above channel coding and information source coding to take out digital voice data, converts it into an analog voice signal by the D / A conversion circuit 35, and outputs voice from the speaker SP. In addition, 36 is a control part and 37 is an antenna.

The portable telephone device constructed in this manner is often used while moving outdoors or the like, and it is inconvenient to record a call using a memo or the like under such a situation. . Therefore, there has been proposed a mobile phone device having a built-in digital memory and capable of recording encoded voice (Japanese Patent Laid-Open No. 4-29447).

Accordingly, if a digital memory is incorporated in a digital portable telephone device, the voice of the other party of the call is sent from the base station as modulated encoded voice data, which can be decoded and recorded. Since the voice encoder is provided, the voice of the caller can be recorded.

However, in the method of voice encoding and decoding used in the digital mobile phone device, when processing each segment (each frame) of the transmission voice and the reception voice, the segment of the voice before that is processed. Encoding and decoding are performed based on the internal state information of the voice encoder and the voice decoder resulting from the encoding or decoding process. The internal state information is, for example, the contents of the adaptive codebook in a VSELP type speech encoder or decoder, the initial states of the shift registers of the three filters, and the LP of the previous frame.
The C coefficient is the energy of the previous frame.

Therefore, in the case where the encoded voice data is stored by incorporating the digital memory as described above, the internal state information cannot be used at the beginning of the recorded voice at the time of reproduction, so that the voice cannot be reproduced. Problems such as clarity and deterioration of voice arise.

SUMMARY OF THE INVENTION An object of the present invention is to provide, in order to solve the above-mentioned problems of the prior art, a digital type portable telephone device in which the beginning of a voice is not ambiguous or sound quality is deteriorated during reproduction.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is a digital type portable telephone configured to write and read digital data and to transmit and receive modulated encoded voice data. A device,
At the time of recording, there are two systems of encoding on the transmitting side and the receiving side, which are composed of encoded voice data input from a microphone of a mobile phone device and voice-encoded, and encoded voice data received from a base station and demodulated. In addition to storing the audio data, the internal state information of the audio encoder and the audio decoder at the start of storage of the encoded audio data of these two systems is also stored, and the stored internal states of each of them are reproduced. The beginning of each encoded voice data is decoded based on the information.

That is, on the transmitting side, a voice encoder which is input from a microphone and is A / D converted is encoded for each frame and converted into encoded voice data, and on the receiving side is encoded. A voice decoder that decodes voice data frame by frame and inversely converts it into a digital voice signal, and the modulated coded voice data that is sent from the base station during a call is demodulated and also sent to the base station. A mobile phone device comprising: a high-frequency part in which encoded audio data is modulated; and a speaker that reproduces a D / A converted audio signal decoded by the audio decoder.
Storage means for storing two systems of encoded voice data composed of encoded voice data on the transmitting side encoded by the voice encoder and encoded voice data on the receiving side demodulated by the high frequency unit. When the encoded voice data on the transmitting side is stored, the internal state of the voice encoder at the storage start time, which is the encoding processing result before the encoded voice data on the transmitting side to be stored. When the information is stored and the encoded voice data of the receiving side is stored, the internal state of the voice decoder at the storage start time which is the decoding processing result before the stored encoded voice data of the receiving side is stored. Information is stored,
When the stored two-system coded voice data is reproduced, the stored voice coded data on the transmitting side is based on the internal state information of the voice coder at the beginning of the storage. The stored encoded voice data on the receiving side is a mobile phone device in which the head frame is decoded based on the internal state information of the voice decoder at the start of storage.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, an embodiment relating to a digital car telephone system which is a kind of digital mobile phone device will be described below. FIG. 1 is a block diagram showing a circuit configuration of an automobile telephone device of the present embodiment, the basic configuration of which is a mobile telephone device of FIG. 4 described as a conventional technique in which a storage means for storing encoded voice data is incorporated. Microphone MC, A / D conversion circuit 1, speech encoder 2, high frequency unit 3, speech decoder 4, D / A conversion circuit 5,
The control unit 6, the antenna 7, the speaker SP, a memory M for storing encoded voice data, and switches SW1 and SW2.

The switches SW1 and SW2 connect the memory M to the transmission lines on the transmitting side and the receiving side by, for example, pressing a recording start button when recording is required during a call.

Therefore, in the memory M, the switchers SW1 and SW2 are provided with the encoded voice data encoded by the encoder 2 on the transmitting side and the encoded voice data demodulated by the high frequency section 3 on the receiving side. It is possible to store each at the same time or to store only one of them.

When the call contents stored in the memory M are reproduced after the end of the call, each frame of the coded voice data of two systems is read from the memory M to the voice decoder 4 in a time division manner. D / A conversion circuit 5 multiplexed
The voice can be output from the speaker SP via.

By the way, in the digital car telephone system, a voice coding system called VSELP system is adopted. VSELP audio decoder 4
2 has a block structure as shown in FIG. 2 and has two codebooks, that is, an adaptive codebook 11 and a vector sum codebook 12, and the vector sums of these codebook outputs are connected in three cascaded pitch pres. Filter f1,
Voice is generated by passing through the synthesis filter f2 and the post filter f3. At this time, the VSELP-type speech decoder 4 encodes the speech data of the speech in the 20-millisecond section (hereinafter referred to as a frame) and the speech decoder 4 which is the processing result of the previous frame. Based on the internal state information, two codebook outputs, gains to be multiplied by the codebook outputs, three filter coefficients, and the initial state of the internal shift register are determined. The internal state information of the speech decoder 4 is specifically the contents of the adaptive codebook, the initial states of the shift registers of the three filters, the LPC coefficient of the previous frame, and the energy value of the previous frame. Further, what corresponds to the internal state information of the speech decoder 4 also exists inside the speech encoder 2, and this is generated and held in the speech encoder 2 in the process of speech encoding. In addition, the block diagram of the VSELP-type speech coder 2 analyzes the two codebook outputs, the gains to be multiplied by each codebook, and the coefficients of the three filters in the VSELP-type speech decoder as described above. , And is well known to those skilled in the art.

Then, when voice recording is started by a recording start operation such as the above-mentioned recording button in the middle of a call, on the transmitting side, the encoding processing result at the start of storage, that is, before the stored encoded voice data is stored. The internal state information of the voice encoder 2 and the encoded voice data encoded by the voice encoder 2 are both stored in the memory M. Also on the receiving side, the internal state information in the voice decoder 4 which is the result of the decoding processing of the frame at the recording start time, that is, before the stored encoded voice data and the received encoded voice data are both stored in the memory M. Remembered. Internal state information is added to the first frame of each encoded voice data of two systems of transmission and reception, as shown in (a) Storage format of transmitting side and (b) Storage format of receiving side in FIG. 3 respectively. It is stored in the storage format.

When the voice is reproduced after the end of the call, the voice decoder 4 first selects the voice encoder 2 and the voice decoder 4 among the data of the format of FIG. 3 stored in the memory M. The internal state information is read and the contents of the adaptive codebook and the initial states of the shift registers of the three filters are set, the LPC coefficient of the previous frame and the energy of the previous frame are held, and then each encoded speech data is framed. Each time, it reads in time division, and the voice decoding is performed. Therefore, the decoding of the first frame of the encoded audio data, that is, the decoding of the beginning of the audio is processed based on the internal state information at the time of recording, so that the reproduced audio can be reproduced clearly from the beginning without deterioration in sound quality. become.

In the above embodiment, the case where the recording is started during the call is explained. However, when the recording is started from the beginning of the call, it is before the beginning of the stored voice, that is, the stored encoded voice. There is no processing result of encoding and decoding before the first frame of data. Therefore, in such a case, either the transmitting side or the receiving side stores only the encoded voice data without adding the internal state information, or adds the predetermined internal state information and stores the encoded voice data. So when you play it, the beginning of the voice is unclear,
There is a risk of sound quality deterioration. For such inconvenience,
The present invention can be supported by the following embodiments.

That is, the portable telephone device of the present invention can be configured as follows, and in the block diagram shown in FIG. 1, the area of the memory M is divided into two, and the first memory area has a call. The encoded voice data at the time is always stored, and after the call, while the user plays the voice stored in the first memory area, the user may cut out a portion that seems to be necessary and transfer it to the second memory area. , Can be configured by known technology.

This is because, for example, when the voice recorded in the first memory area is being reproduced and cut out and transferred to the second memory area, the voice decoder 4 sends the voice from the first memory area to the transmitting side. , Each frame of the encoded voice data of the two systems on the receiving side is time-divisionally read, multiplexed and reproduced, and the internal state information of the voice decoder 4 is added to each of the two systems by the transfer start operation of the user. Then, the encoded voice data on the transmitting side and the receiving side are transferred to the second memory area.

With such a structure, it is possible to selectively record a necessary portion while reproducing the call contents after the call. Therefore, only the necessary portion in the middle of the first memory area in which all the call records are recorded can be transferred to the second memory area, and the memory in the first memory area can be erased, so that the memory can be efficiently used. Moreover, the necessary portion stores the encoded voice data together with the internal state information of the voice decoder 4 which is the result of the decoding process of the previous frame in the second memory area, so that its reproduction is clear from the beginning and the sound quality is improved. It is possible to output sound without deterioration.

[0021]

According to the present invention, it is possible to reproduce the stored call contents clearly from the beginning of the voice and without deterioration of the sound quality.
Playback can be performed with voice quality equivalent to that during a call.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a car telephone which is an embodiment of the present invention.

FIG. 2 is a block diagram of a VSELP audio decoder.

FIG. 3 is a voice storage format according to an embodiment of the present invention, in which (a) is a transmission side storage format and (b) is a reception side storage format.

FIG. 4 is a block diagram showing a circuit configuration of a conventional digital mobile phone device.

[Explanation of symbols]

 2 speech coder 3 high frequency section 4 speech decoder 11 adaptive codebook 12 vector sum codebook M memory

Claims (1)

[Claims] 1. A voice coder for encoding a voice signal, which is input from a microphone and A / D converted, for each frame on the transmitting side and is converted into encoded voice data, and encoding on the receiving side. A voice decoder that decodes the voice data frame by frame and inversely converts it into a digital voice signal, and the modulated coded voice data that is sent from the base station during a call is demodulated and also sent to the base station. A mobile phone device comprising: a high-frequency section for modulating encoded voice data; and a speaker for reproducing a D / A converted voice signal decoded by the voice decoder. Storage means for storing two systems of encoded voice data, which is encoded voice data on the transmitting side and encoded voice data on the receiving side demodulated by the high frequency unit, When the encoded voice data on the transmitting side is stored, internal state information of the voice encoder at the storage start time which is a result of encoding processing before the encoded voice data on the transmitting side to be stored is stored. When the encoded voice data of the receiving side is stored, the internal state information of the voice decoder at the storage start time which is the decoding processing result before the stored encoded voice data of the receiving side is stored. When the stored two-system encoded voice data is reproduced, the stored voice encoded data on the transmitting side is the internal state information of the voice encoder at the beginning of the storage of the head frame. And the stored encoded voice data on the receiving side is decoded based on the internal state information of the voice decoder at the start of storage of the portable frame. Telephone device.