JPH07177217A - Dial tone detecting method for automatic answering telephone - Google Patents

Abstract

PURPOSE:To easily and surely detect a dial tone following an answer message without depending upon the kind of an equipment by dividing an audible signal into time-series blocks and inspecting the voiced/voiceless states of the blocks and zero-crossing frequency variation. CONSTITUTION:A speech circuit 5 divides the audible tone from an opposite- party automatic answering telephone 1 into the time-series blocks. A voiced/ voiceless decision part 101 inspects mean electric power, block by block, through a mean electric power detection part 106 and stores decision data on a voiced state in an FIFO buffer 10 when, for example, a specific threshold value is exceeded. A zerocrossing frequency count part 103 counts the zero-crossing frequency of the signal tone, block by block, and stores the difference from a last block in an FIFO buffer 104. A discrimination condition decision part 105 analyzes the data stored in the FIFO buffers 102 and 104 and decides that the dial tone is received from the opposite-party automatic answering telephone 1 when a specific number of blocks which are in the voiced state and less than in zero-crossing frequency than specified succeed. A voice information sending-out part 6 sends out specific voice information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dial tone detection method for an answering machine.

[0002]

2. Description of the Related Art A conventional example of a dial tone detection method for an answering machine will be described. When automatically transmitting voice mail or various notifications and other voice information to a telephone subscriber through a telephone line, if the terminal device on the subscriber side is an answering machine, pre-register on the answering machine. It is necessary to send the voice information from me after the reproduction of the response message being performed is finished and then the dial tone is output.

When sending voice information to an answering machine, conventionally, a method of sending voice information immediately after connecting a line (see Japanese Patent Laid-Open No. 26262/1992) or a voice of a response message sent from an answering machine is used. The method of detecting the end of the section and transmitting the audio information based on this is adopted (see Japanese Patent Laid-Open No. 2-184163). But,
The method of transmitting voice information immediately after connecting the line cannot correctly transmit the voice information of the other party because the reproduction period of the answering message of the answering machine and the reproduction transmission period of the voice information to be delivered overlap. There are cases.

In the method of detecting and depending on the end of the voice section of the response message, the volume of the response message of the other party, ambient noise on the other party, and other conditions are various. It is necessary to absorb the difference between the two and accurately detect the end of the voice section, but this processing becomes very complicated. Even if it is possible to detect the end of the voice section of the response message, if the voice information is sent from me before the dial tone is sent from the other party following the response message, the answering machine model In some cases, the voice information is transmitted from me even though the recording of the answering machine is not actually started, which eventually causes a problem that the head portion of the voice information is missing from the recording.

As described above, in the conventional method, there is a case in which the voice information cannot be transmitted to the other party without omission because the timing when the answering machine starts recording cannot be accurately detected.

[0006]

DISCLOSURE OF THE INVENTION The present invention detects the dial tone of an answering machine accurately and easily, and by this means, it does not depend on the length of the answering message of the answering machine or the model of the answering machine, and the proper timing. Provides a method for detecting the dial tone of an answering machine, which is capable of transmitting voice information to the answering machine.

[0007]

[Means for Solving the Problems] In a dial tone detection method for an answering machine, which detects a dial tone transmitted from an answering machine following a response message, an audible tone transmitted from the answering machine is divided into a plurality of time series blocks. Then, whether each time-series block is voiced or silent is output as voiced / silent time-series data, and the fluctuation of the zero-crossing number of each time-series block is output as zero-crossing number fluctuation time-series data. However, based on the fluctuation of each block of the voiced / silent time-series data and the zero-crossing number fluctuation time-series data, the audible time-series blocks are continuously voiced over a certain number of blocks, and
If the variation of the number of zero crossings in a time series block is smaller than a certain fixed value, the audible sound in the consecutive blocks is determined to be the dial tone transmitted from the answering machine. Configured.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is an answering machine for transmitting voice information via a telephone line, 2 is a public telephone line network,
The answering machine 1 is connected to the public telephone line network 2. Reference numeral 3 is a response detecting section for detecting a response from the answering machine 1, and 4 is a calling section.

Reference numeral 5 is a communication circuit, 6 is a voice information sending unit, 7 is a control unit, and 100 is a dial tone detection device used in implementing the present invention. The dial tone detection device 100 includes a voice / silence determination unit 101, a FIFO buffer 102 that stores the determination results of the voice / silence determination unit 101 for a certain past time, a zero-crossing number coefficient unit 103, and a zero-crossing number counting unit. 103
F, which stores the difference that is the amount of change over the past certain time
It is composed of an IFO buffer 104, an identification condition determination unit 105, and an average power detection unit 106.

Here, the answering machine 1 connected to the public telephone line network 2 automatically performs a calling operation via the calling section 4, and the response detecting section 3 detects the response.
After the response is detected, the audible sound including the response message transmitted from the answering machine 1 is received and analyzed, and the dial tone transmitted subsequently to the audible sound is detected.
The voice information set in advance is transmitted from me.

The dial tone detection device 100 used for implementing the present invention will be described below. The dial tone detection device 100 detects the response of the answering machine 1, and then divides the audible sound output from the answering machine 1 into a plurality of time series blocks by the communication circuit 5, and the time series blocks are divided into average power detection units. 106 and zero-crossing number counting unit 10
Fill in each of the three. In the sound / silence determining unit 101, the sound of the block is detected based on the in-block average power which is the detection result of the average power detecting unit 106 and the in-block zero crossing number which is the counting result of the zero crossing number counting unit 103. /
Determine silence. For example, two thresholds of high and low are set for the average power in the block, and if the average power in the block is a value higher than the high threshold, the block is voiced, if the average power in the block is lower than the low threshold, it is silent, and between the high and low thresholds. For example, sound / silence of the block is determined by the number of zero crossings in the block. The determination result is sequentially stored as a history in the FIFO buffer 102 over a certain past block. The result of this determination is illustrated in FIG.

In the zero-crossing number counting unit 103, the number of zero-crossings in the input block is counted, and the difference from the number of zero-crossings in the preceding block is counted to determine the FIFO buffer 10.
4, and the difference is sequentially stored in the FIFO buffer 104 as a history over a certain past block. The accumulated zero-crossing number waveform is as shown in FIG. In the identification condition determination unit 105, the FIFO buffer 10
The voice history / non-voice determination history accumulated in 2 and the difference history of the number of zero crossings accumulated in the FIFO buffer 104 are analyzed.
The judgment history of voiced / non-voiced sound accumulated in the FIFO buffer 102 is continuously voiced over a certain number of blocks, and the number of zero-crossings accumulated in the FIFO buffer 104 as in the dial tone portion shown in FIG. When the difference history of is smaller than the threshold value continuously in the block, a response indicating that the input audible sound is the dial tone of the answering machine 1 is output to the control unit 7 as a determination result.

When the control unit 7 receives the determination result indicating that it is the dial tone of the answering machine 1, from the identification condition determining unit 105, it controls the voice information sending unit 6 to pre-designate the answering machine 1 from here. A certain voice information is transmitted via the public network 2. According to the present invention, since the dial tone transmitted continuously for a certain period of time following the answering message of the answering machine is a continuous tone or a continuous tone composed of a combination of single tones,
It should be noted that the block of the dial tone is sounded continuously for a certain period of time, and the fluctuation of the number of zero crossings of the block of the dial tone is significantly smaller than that of the other blocks. Here, it is determined that each block of the audible sound is continuously voiced for a predetermined number of blocks, and the fluctuation of the number of zero crossings of each block is continuously for a predetermined block or less than a certain value. If it is, it is possible to detect only the dial tone of the audible tones that are sent subsequently to the response message in the answering machine by determining that this continuous block of the audible tone is the block of the dial tone. .

[0014]

As described above, according to the dial tone detection method of the answering machine of the present invention, the audible tone is transmitted from the answering machine by analyzing the average power in the block and the number of zero crossings in the block. The presence / absence of audible sound can be determined, and the time variation of the number of zero crossings can be sequentially analyzed to easily and reliably detect the dial tone of the answering machine.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating an embodiment of the present invention.

FIG. 2 is a graph showing a response message waveform of an answering machine, a sound / no-sound determination result of this waveform, and the number of zero crossings of this waveform.

[Explanation of symbols]

 1 Answering machine 2 Public telephone line network 3 Incoming call detection section 4 Calling section 5 Calling circuit 6 Voice information sending section 7 Control section 100 Dial tone detection device 101 Voice / silence detection section 102 FIFO buffer 103 Zero crossing counting section 104 FIFO Buffer 105 Identification condition determination unit 106 Average power detection unit

Claims (1)

[Claims] 1. A method of detecting a dial tone of an answering machine, which detects a dial tone transmitted from an answering machine following a response message, wherein an audible tone transmitted from the answering machine is divided into a plurality of time series blocks, and each time block is divided. Whether the sequence block is voiced or silent is output as voiced / non-voiced time series data, and the fluctuation of the zero-crossing number of each time-series block is output as zero-crossing number fluctuation time-series data. / Silence time series data and fluctuation of zero crossings Based on the fluctuation of each block of time series data, the time series blocks of audible sound are continuously voiced over a fixed number of blocks, and the number of zero crossings of time series blocks If the fluctuation of is less than a certain fixed value, it is determined that the audible sound in the consecutive blocks is the dial tone transmitted from the answering machine. Detection method.