JP2853166B2 - Voice data conversion circuit in digital radio telephone equipment. - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice data conversion circuit in a digital radio telephone, and more particularly to a voice data conversion circuit using a PCM / CODEC and an ADPCM / CODEC.

[Conventional technology]

FIG. 2 shows the configuration of a conventional audio data conversion circuit of this kind. In the figure, transmission voice analog data 201 from the own telephone device is converted into transmission PCM data 203 by PCM / CODEC 21 and further converted into transmission ADPCM data 208 by ADPCM / CODEC 22 to generate transmission data. ADPCM data 209 received from another station is received by ADPCM / CODEC 22.
The data is converted to 04, then converted to the received voice analog data 202 by the PCM / CODEC 21, and the voice is output from the own telephone device.

Since no wireless line is connected during no call, there is no received data, and ADPCM / CODEC 22 has significant received ADPCM data 209.
Is not entered. For this reason, the received PCM data 204 output from the ADPCM CODEC 22 is data that becomes noise.

On the other hand, when a wireless line is connected and a call is started, AD
PCM / CODEC22 contains significant ADPCM data 2 related to voice
09 starts to be input, but even if the input data suddenly changes from invalid data to audio ADPCM data, the ADPCM / CODEC22 still has the state of the previous invalid data inside the ADPCM / CODEC22, so immediately I can't answer. Therefore, the noise data due to this response delay
The received PCM data 204 is output from the ADPCM / CODEC 22 to the PCM / CODEC 21.

If no countermeasures are taken against the noise data as described above, a loud unpleasant sound will be emitted from the telephone device immediately after the start of a call. Therefore, conventionally, the transmission / reception control unit 23 shown in FIG.
After detecting the call start by the CODEC ON signal 212 output by the PCM, the PCM / CODEC control unit 27 puts the PCM / CODEC 21 into the power-down state by the Power / Down signal 213 until the internal timer measures a certain time, The received voice analog data 202 of the PCM / CODEC 21 is forcibly silenced to eliminate unpleasant sounds.

[Problems to be solved by the invention]

In the above-described voice data conversion circuit in the conventional digital radio telephone device, a PCM / CODEC control unit having a timer is used.
27 is PCM / C until a certain time elapses immediately after the call starts.
The ODEC21 is powered down and the PCM / CODEC21 analog output is forcibly silenced to eliminate unpleasant sounds, such as immediately after the start of a call.However, after voice data is input to ADPCM / CODEC22, noise data Time until output stops and audio data starts to be output (rise time)
Is not clear, it is difficult to set the timer value. For this reason, there has been a problem that the timer value is too short and unpleasant sound remains, and on the contrary, the timer value is too long and the first part of the call is cut off.

SUMMARY OF THE INVENTION An object of the present invention is to provide a voice data conversion circuit in a digital radio telephone device that can reliably prevent such unpleasant sounds and disconnection of a call.

[Means for solving the problem]

In order to achieve the above object, the voice data conversion circuit in the digital wireless telephone device of the present invention has a PCM / CODEC for converting between analog data and PCM data, and an ADPCM / CODEC for converting between PCM data and ADPCM data. In the digital radio telephone device comprising: a silent pattern generating means for generating a silent pattern of PCM; a detecting means for detecting the presence or absence of data received from another station; and ADPCM data output from the ADPCM / CODEC and receiving. One of the ADPCM data and the one corresponding to the detection result of the detection means is the ADPCM CODEC
The first selection means to be input to the PCM data, and one of the PCM data output from the ADPCM / CODEC and the silent pattern of the PCM output from the silent pattern generation means in accordance with the detection result of the detection means, Second selection means for inputting to the PCM / CODEC.

[Action]

In the voice data conversion circuit in the digital radio telephone apparatus of the present invention, when the detecting means detects that no data is received from another station, the first selecting means sets the ADPCM
-Select ASPCM data output from CODEC and select its ADPC
Returning to the M-CODEC, the second selecting means selects the PCM data output from the silent pattern generating means, and
To enter. Therefore, in a situation where the wireless line is not connected and there is no received data from another station, the PCM / CODEC converts the silent pattern and outputs a silent analog signal, and no noise is output from the telephone device. Further, the ADPCM / CODEC performs an operation of converting the ADPCM data output by itself to PCM data.

When the wireless line is connected and data is received from another station,
It is detected by the detecting means, and the first selecting means selects the ADPCM data received by the digital radio telephone device and
Input to DPCM / CODEC and the second selection means
Select PCM data output from DPCM / CODEC and select PCM / C
Input to ODEC. Here, the ADPCM data, which is its own output, has been input to the ADPCM / CODEC immediately before. This ADPCM data is input to the digital wireless telephone device immediately before connection to the wireless line.
The converted data is processed and is significant data related to audio. For this reason, the ADPCM / CODEC does not have a period in which no significant data is input, and does not generate noise data due to a delay in response. Therefore, no noise is generated in the analog output output from the PCM / CODEC, and no unpleasant sound is generated immediately after the call starts.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a main part of an embodiment of a voice data conversion circuit in a digital radio telephone apparatus according to the present invention.
The difference between the audio data conversion circuit of the present embodiment and the conventional circuit of FIG. 2 is that the start code detection unit 13, the selector 14,
The point is that a selector 15 and a shift register 16 are added.

The shift register 16 presets a pattern corresponding to PCM silence in synchronism with the frame synchronization clock 113 input to the PCM / CODEC 11, and outputs an operation clock (PCM / CODEC clock) 105 also input to the PCM / CODEC 11. A silent pattern generating means for outputting the preset value in synchronization is constituted, and the silent pattern of the PCM generated here is applied to one input of the selector 15.

The start code detection unit 13 constitutes means for detecting the connection state of the wireless line. Generally, data received from other stations includes preamble, start code and audio ADPCM.
Consists of data. This start code detector 13
Always checks whether or not the received data includes a start code, and if a start code is detected, outputs a Start / det signal 111 indicating that the start code is being received to the selectors 14 and 15 for a predetermined time. I do. Therefore, during reception of a series of reception data including audio ADPCM data, the Start / det signal 111 is output from the selector 14 and the selector 1
In addition, when such data is no longer received, the Start.det signal 111 is not supplied to the selector 14.

The selector 14 receives the ADPCM data 109 and the ADPCM CODEC 12
And the transmission ADPCM data 108 output from the
During the period when the Start / det signal 111 is transmitted, the reception ADPCM
Select data 109, and use it for ADPCM / CODEC input
The data is sent to the ADPCM / CODEC 12 as data 110, and during the period in which there is no Start / det signal 111, the transmission ADPCM data 108 is selected and returned to the ADPCM / CODEC 12.

On the other hand, the selector 15 receives the PCM data 104 output from the ADPCM CODEC 12 and the PC output from the shift register 16.
An M silence pattern 106 is input, and during the period in which the Start / det signal 111 is being transmitted, the received PCM data 104 is selected, and this is sent to the PCM / CODEC 11 as PCM / CODEC input data 107, and the Start / det signal 111 PCM silence pattern 10 during periods without
It works by selecting 6 and sending it to PCM / CODEC11.

 Next, the operation of this embodiment will be described.

During a period in which the wireless line is not connected and data is not received from another station, the start code detection unit 13 cannot detect the start code, so that the start / det signal 111 is not transmitted, and the selector 14 transmits the transmission ADPCM data 108. Selected,
The selector 15 selects the PCM silent pattern 106. As a result, the transmission analog data 101 relating to the voice input to the digital wireless telephone device is transmitted by the PCM / CODEC 11 to the transmission PCM.
The data 103 is converted to data 103, which is further converted to the transmission ADPCM data 108 by the ADPCM / CODEC 12.
Returned to EC12, ADPCM CODEC12 receives it PCM data 1
This means that conversion to 04 is being performed. The PCM silence pattern 106 generated by the shift register 16 is
Is input to PCM / CODEC11, and PCM / CODEC11
The received analog data obtained by converting the PCM silent pattern, that is, analog data corresponding to silence is output.
Therefore, no noise occurs during a period in which data is not received from another station.

When a wireless line is connected and data from another station is received, a start code is detected by the start code detecting unit 13 and a Start / det signal 111 is output. In response to this, the selector 14 selects the received ADPCM data 109 and selects ADPCM · C
The selector 15 selects the received PCM data 104 and sends it to the PCM CODEC 11. Here, input of ADPCM / CODEC12
Since the ADPCM data 110 is data relating to the sound obtained by converting the transmission analog data 101 even before the wireless line is connected, the ADPCM / CODEC 12 does not enter a state in which valid data is not input, and There is no delay in response from the input state and no noise is generated. Therefore, no noise is generated in the output (received analog data 102) of the PCM / CODEC 11 which performs the conversion operation by inputting the received PCM data 104 which is the output via the selector 15, and the received ADPCM data 109 indicates An analog output corresponding to the voice of the above is output immediately.

〔The invention's effect〕

As described above, in the voice data conversion circuit in the digital wireless telephone device of the present invention, the PCM / CODEC inputs the silent pattern of the PCM during the period when the wireless line is not connected and no data is received from another station. Therefore, no noise is output from the telephone device. Also, it output itself to ADPCM / CODEC just before the wireless line was connected.
Since the ADPCM data is returned, there is no significant input state of ADPCM / CODEC in the ADPCM / CODEC.Therefore, when the received ADPCM data received from another station is input to the ADPCM / CODEC after the wireless line is connected, the response is delayed. Does not cause noise. Further, when data from another station cannot be received during a call, there is an effect that the received analog data can be silenced regardless of the transmitting side.

[Brief description of the drawings]

 FIG. 1 is a block diagram of a main part of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional example. In the figure, 11 PCM / CODEC 12 ADPCM / CODEC 13 start code detector 14, 15 selector 16 shift register 101 transmission analog data 102 reception analog data 103 transmission PCM data 104 reception PCM data 105 PCM / CODEC clock 106 ... PCM silence pattern 107 ... PCM / CODEC input data 108 ... Transmit ADPCM data 109 ... Receive ADPCM data 110 ... Input ADPCM data 111 ... Start / det signal 112 ... Receive data 113 ... Frame synchronous clock

Claims (1)

(57) [Claims] 1. A digital wireless telephone device comprising a PCM / CODEC for converting between analog data and PCM data and an ADPCM / CODEC for converting between PCM data and ADPCM data, wherein a silent pattern of PCM is generated. Silence pattern generation means, detection means for detecting the presence or absence of data received from another station, one of the ADPCM data output from the ADPCM CODEC and the received ADPCM data in accordance with the detection result of the detection means First selection means for inputting the ADPCM / CODEC to the detection result of the detection means among the PCM data output from the ADPCM / CODEC and the silent pattern of the PCM output from the silent pattern generation means. PCM / COD
A voice data conversion circuit in a digital wireless telephone device, comprising: a second selection unit for inputting to an EC.