JP5887736B2 - DTMF signal detection apparatus, DTMF signal detection method, and DTMF signal detection program - Google Patents

Description

  The present invention relates to a DTMF signal detection device, a DTMF signal detection method, and a DTMF signal detection program, and more particularly to a DTMF signal detection device that can process a large number of sessions.

  A DTMF (Dual-Tone Multi-Frequency) signal is an analog audio signal generated in response to an operation of an operator pressing a push button on a telephone. Generally, it is often called a tone signal. This DTMF signal not only transmits the telephone number of the called party to the telephone exchange, but also provides an IVR (Interactive Voice Response) that provides voice services such as a call center, telephone banking, and an automatic reservation system (such as a ticket). It is also often used to input contents selected by the user, such as ID numbers and processing contents, in an automatic response system.

  The DTMF signal is an ITU-T (International Telecommunication Union Telecommunication Standardization Sector). 24 is defined as an international standard. According to this standard, the DTMF signal selects one of the low group frequencies of 697 Hz, 770 Hz, 852 Hz, and 941 Hz, and one of the high group frequencies of 1209 Hz, 1336 Hz, 1447 Hz, and 1644 Hz. Thus, the audio signal is output by synthesizing the sine wave having the low group frequency and the sine wave having the high group frequency.

  As a result, the DTMF signal can represent 16 types of signals such as the numbers “0” to “9” and “*”, “#”, “A”, “B”, “C”, and “D”. General telephone terminals are provided with 12 types of keys (ie, numbers “0” to “9” and “*” “#”) excluding “A”, “B”, “C”, and “D”. When a user presses a key, a DTMF signal synthesized with a frequency corresponding to the key is sent as an analog voice signal to a telephone exchange or a DTMF signal detection device.

  In the IVR system as described above, the service provider gives the user voice guidance including options such as “If you select XX, press No. 1, if you select XX, press No. 2,” etc. DTMF signal included in the audio signal received from the telephone terminal operated by the user corresponding to this is detected by the DTMF signal detection device, and the type of the detected signal (ie, the key pressed by the user) The IVR system is configured and operated so as to perform processing according to the type of the above.

This ITU-T Q.I. 24 defines the frequency and minimum duration of the DTMF signal. In the case of the general NTT system in Japan, the minimum duration is specifically defined as follows.
(1) The minimum duration of the DTMF signal is 40 ms (the DTMF signal needs to be continuously transmitted for 40 ms or more)
(2) Maximum interruption time is 10 ms (even if there is an interruption of 10 ms or less, it is necessary to treat it as the same signal)
(3) The minimum pause time between DTMF signals is 30 ms (it is necessary to put a pause of at least 30 ms between two DTMF signals)
(4) Signal speed is 120 ms / digit (transmission time of one signal + pause time needs to be 120 ms or more)

  FIG. 31 is an explanatory diagram showing the configuration of the DTMF signal detection device 910 described in Patent Document 1 and the like. The DTMF signal detection device 910 includes a plurality of frequency deviation analyzers (hereinafter simply referred to as frequency analyzers) 911a-b for analyzing the intensity of the frequency used in the DTMF signal included in the input audio signal, and frequency analysis. A DTMF signal determination unit 912 that determines whether or not a DTMF signal has been received based on the analysis result of the detector.

  The frequency analyzers 911a to 911b perform discrete Fourier transform (DFT) on different frequency components on the data for a certain time of the input audio signal, and thereby each frequency component used in the DTMF signal. Detect intensity. The DTMF signal determiner 912 determines whether or not a DTMF signal has been received from the intensity of each frequency component detected by the frequency analyzers 911a-b, and at the same time, the type of the received DTMF signal (ie, the key pressed by the user) Type) and output this.

  FIG. 32 is a time chart showing the operation of the frequency analyzers 911a and 911b shown in FIG. In FIG. 32, the horizontal axis represents time, and the double arrows on the timeline represent analysis intervals of the frequency deviation analyzers 911a and 911b. In the frequency deviation analyzers 911a to 911b, by using a plurality of frequency analyzers 911a to 911b, it is possible to overlap the frequency analysis sections, and the analysis section (specifically, 18.75 ms) is lengthened. In addition, the analysis cycle (specifically, 13.125 ms) is shortened to improve detection accuracy for a short-time DTMF signal.

  In addition to the above, there are the following technologies related to the DTMF signal detection apparatus. Among them, Patent Document 2 describes a DTMF signal detection device that detects a continuation time during which no DTMF signal is detected and prevents erroneous detection. Patent Document 3 describes the setting of the number of samples and the frequency point in detection of a DTMF signal by DFT.

  Patent Document 4 discloses a tone that first analyzes a DTMF signal by a coarse frequency analyzer, outputs the DTMF signal to a different individual detector from the analysis result, and analyzes it to reduce the amount of calculation required for the analysis. A (DTMF) signal detector is described. Patent Document 5 describes a tone detector that detects a tone (DTMF) signal at different timings by a plurality of tone determination units.

JP 2000-324519 A Japanese Patent Laid-Open No. 2001-112033 JP 2002-223460 A JP 2002-252675 A JP 2003-174522 A

  As described above, the DTMF signal detection apparatus or the IVR system using the DTMF signal detection apparatus is widely used in voice services such as a call center, telephone banking, and an automatic reservation system. Naturally, one DTMF signal detection device is required to process connections (sessions) from a larger number of connection destinations (telephones), that is, to improve the number of sessions that can be processed. In addition, in order to improve the convenience of the user who operates the telephone, DTMF with a short duration (that is, the number of seconds for which the user keeps pressing one key) while maintaining a detection accuracy that can withstand practical use for the DTMF signal. It is also required that the signal be detectable.

  Therefore, it is useful to always use a plurality of frequency analyzers for each session as in the above-mentioned Patent Document 1.

  However, this increases the processing load on each frequency analyzer. In particular, when a frequency analyzer that performs processing for a plurality of sessions is realized by a single computer, the processing load is large, and there is a limit to increasing the number of sessions that can be processed simultaneously.

  The techniques described in Patent Documents 2 to 5 are not intended to increase the number of sessions that can be processed simultaneously, and are not available for that purpose. Therefore, even if all the techniques described in Patent Documents 1 to 5 are combined, the technique cannot solve this problem.

  An object of the present invention is to provide a DTMF signal detection apparatus, a DTMF signal detection method, and a DTMF signal detection program capable of significantly improving the number of sessions that can be processed within a unit time.

In order to achieve the above object, a DTMF signal detection apparatus according to the present invention is detected by detecting the presence or absence of a DTMF (Dual-Tone Multi-Frequency) signal composed of two different frequency components from an input audio signal. A DTMF signal detection device for outputting the type of the DTMF signal, the frequency analysis means for analyzing the intensity of each use frequency predetermined as the standard of the DTMF signal in the audio signal, and the analysis result of the frequency analysis means DTMF signal determining means for determining whether or not a DTMF signal included in the audio signal is being detected and the type of the DTMF signal and outputting them, and according to the determination result of the DTMF signal determining means, Frequency analysis control means for instructing suppression of operation, and the frequency analysis control means is configured to receive a DTMF signal output from the DTMF signal determination means. A determination result receiving unit that receives detection information indicating whether or not detection is in progress; a determination result storage unit that stores the received detection information as a detection state table in a storage unit provided in advance; and the contents of the detection state table And a frequency analysis accuracy determination unit that determines the required detection accuracy of the DTMF signal, and an instruction transmission unit that transmits the determined detection accuracy to the frequency analysis means .

In order to achieve the above object, a DTMF signal detection method according to the present invention is detected by detecting the presence or absence of a DTMF (Dual-Tone Multi-Frequency) signal composed of two different frequency components from an input audio signal. In the DTMF signal detection device that outputs the type of the DTMF signal, the frequency analysis means analyzes the intensity of each use frequency that is predetermined as the standard of the DTMF signal in the audio signal, and the analysis result of the frequency analysis means Whether or not the DTMF signal included in the signal is being detected and the type of the DTMF signal is determined by the DTMF signal determining means and outputted , and whether the DTMF signal output from the DTMF signal determining means is being detected. The determination result receiving unit of the frequency analysis control means receives the detection information indicating whether or not, and the received detection information is stored in the determination result of the frequency analysis control means Is stored as a detection state table in a storage unit provided in advance, and the frequency analysis accuracy determination unit of the frequency analysis control unit determines the required detection accuracy of the DTMF signal according to the contents of the detection state table, and the determined detection accuracy Is transmitted to the frequency analysis means by the instruction transmission unit of the frequency analysis control means to instruct suppression of the operation of the frequency analysis means.

To achieve the above object, a DTMF signal detection program according to the present invention detects the presence or absence of a DTMF (Dual-Tone Multi-Frequency) signal from an input audio signal and outputs the type of the detected DTMF signal. In the DTMF signal detection device, the computer provided in the DTMF signal detection device analyzes the intensity of each use frequency predetermined as the standard of the DTMF signal in the audio signal, and the sound from the analysis result of the intensity of each use frequency Whether or not the DTMF signal included in the signal is being detected, the type of the DTMF signal is determined and output, and detection information indicating whether or not the output DTMF signal is being detected is received. Necessary according to the procedure, the procedure for storing the received detection information as a detection state table in the storage means provided in advance, and the contents of the detection state table A procedure for determining the detection accuracy of the DTMF signal and a procedure for instructing suppression of the detection operation according to the determined detection accuracy are executed.

  In the present invention, as described above, the frequency analysis control unit determines the necessary detection accuracy according to the determination result of the DTMF signal determination unit, and causes the frequency analysis unit to perform the minimum necessary operation according to the detection accuracy. Since it comprised so, the amount of calculations can be reduced significantly. Thus, it is possible to provide a DTMF signal detection apparatus, a DTMF signal detection method, and a DTMF signal detection program having an excellent feature that the number of sessions that can be processed within a unit time can be significantly improved.

It is explanatory drawing shown about the structure of the DTMF signal detection apparatus which concerns on the 1st Embodiment of this invention. It is explanatory drawing shown about the more detailed structure for 1 session of the frequency analysis means shown in FIG. In the frequency analysis means shown in FIG. 2, when there are two frequency intensity analysis units, an example of the start time and end time of the frequency intensity analysis that the control communication unit instructs to these frequency intensity analysis units FIG. It is a table | surface shown about the frequency of the DTMF signal which each frequency intensity | strength analysis part analyzes with the frequency analysis means shown in FIG. It is explanatory drawing which shows an example of the frequency determination method in the DTMF signal determination means shown in FIG. It is a block diagram showing the structure of the frequency analysis control means shown in FIG. It is explanatory drawing shown about the more detailed content of the DTMF signal detection state table shown in FIG. It is a flowchart shown about operation | movement of the DTMF signal detection apparatus shown in FIG. FIG. 9 is a table showing an operation in which a determination result receiving unit updates a DTMF signal detection state table in step S <b> 104 of FIG. 8. FIG. It is explanatory drawing shown about the more concrete structure of the DTMF signal detection apparatus shown in FIG. FIG. 11 is an explanatory diagram showing a frequency intensity analysis operation instructed by the control communication unit to each frequency intensity analysis unit in the server device which is a specific example of the DTMF signal detection apparatus shown in FIG. 10. FIG. 12 is an explanatory diagram showing an operation when a DTMF signal is detected in the operation of frequency intensity analysis by the frequency intensity analysis unit shown in FIG. 11. FIG. 13 is an explanatory diagram illustrating an example of a DTMF detection state table in which a DTMF signal corresponding to “7” is detected and updated in the frequency intensity analysis by the frequency intensity analysis unit illustrated in FIG. 12. FIG. 13 is an explanatory diagram illustrating an example of a DTMF detection state table that is updated with a DTMF signal “not detected” in the frequency intensity analysis by the frequency intensity analysis unit illustrated in FIG. 12. It is explanatory drawing shown about the operation | movement after a DTMF signal is no longer detected by the frequency intensity analysis by the frequency intensity analysis part shown in FIG. It is explanatory drawing shown about the structure of the DTMF signal detection apparatus which concerns on the 2nd Embodiment of this invention. It is explanatory drawing shown about the more detailed structure of the frequency analysis control means shown in FIG. It is explanatory drawing shown about the structure of the audio | voice automatic response apparatus which concerns on the 3rd Embodiment of this invention. It is explanatory drawing shown about the more detailed structure of the DTMF signal detection apparatus shown in FIG. It is explanatory drawing shown about the more detailed structure of the frequency analysis control means shown in FIG. It is a flowchart shown about operation | movement of the DTMF signal detection apparatus shown in FIG. It is a table | surface shown about the detail of the operation | movement which the frequency analysis control means (frequency analysis precision determination part) shown by step S304 of FIG. 21 determines a frequency analysis precision. FIG. 19 is a time chart showing the frequency analysis accuracy determined by the DTMF signal detection device in the automatic speech response device shown in FIG. 18. FIG. It is explanatory drawing shown about the structure of the DTMF signal detection apparatus which concerns on the 4th Embodiment of this invention. It is explanatory drawing shown about the more detailed structure of the frequency analysis means shown in FIG. It is explanatory drawing shown about the more detailed structure of the frequency analysis control means shown in FIG. 27 is a time chart showing an operation of the DTMF signal detection device shown in FIGS. 27 is a flowchart illustrating an operation of the DTMF signal detection apparatus illustrated in FIGS. FIG. 25 is an explanatory diagram showing a more specific configuration of the DTMF signal detection device shown in FIG. 24. 25 is a time chart showing a more specific operation of the DTMF signal detection apparatus shown in FIG. 24. It is explanatory drawing shown about the structure of the general DTMF signal detection apparatus described in patent document 1. FIG. 32 is a time chart showing the operation of the frequency analyzer shown in FIG. 31. FIG.

(First embodiment)
Hereinafter, the configuration of the embodiment of the present invention will be described with reference to the attached FIGS.
First, the basic content of the present embodiment will be described, and then more specific content will be described.
The DTMF signal detection apparatus 10 according to the present embodiment is a DTMF signal detection apparatus that detects the presence or absence of a DTMF signal composed of two different frequency components from an input audio signal and outputs the type of the detected DTMF signal. is there. This DTMF signal detection apparatus 10 includes frequency analysis means 12 for analyzing the intensity of each use frequency predetermined as a standard of the DTMF signal in the audio signal, and the DTMF signal included in the audio signal from the analysis result of the frequency analysis means. DTMF signal determination means 13 for determining presence / absence and type of the DTMF signal and outputting them, and frequency analysis control means 14 for instructing suppression of the operation of the frequency analysis means according to the determination result of the DTMF signal determination means Prepare.

  Here, the frequency analysis means 12 includes a frequency intensity analysis unit 22 that detects the signal intensity for each use frequency that is predetermined as a DTMF signal standard, and the frequency and length of frequency intensity analysis instructed by the frequency analysis control unit. And a control communication unit 24 for instructing each frequency intensity analysis means the start time and the end time of the signal intensity detection process.

  Further, the frequency analysis control unit 14 is provided with a determination result receiving unit 31 that receives detection information indicating whether or not the DTMF signal output from the DTMF signal determination unit is being detected, and the received detection information. A determination result storage unit 32 that stores the detection state table (DTMF signal detection state table 35) in the storage means, and a frequency analysis accuracy determination unit 33 that determines the required detection accuracy of the DTMF signal according to the contents of the detection state table; And an instruction transmission unit 34 for transmitting the determined detection accuracy to the frequency analysis means.

  Then, when the DTMF signal determination unit 13 detects the current DTMF signal, the frequency analysis control unit 14 instructs the frequency analysis unit to suppress the detection accuracy of the DTMF signal immediately after that.

With the above configuration, the DTMF signal detection apparatus 10 of the present embodiment can reduce the amount of calculation related to the detection of the DTMF signal and can process a large number of sessions at the same time.
Hereinafter, this will be described in more detail.

  FIG. 1 is an explanatory diagram showing a configuration of a DTMF signal detection apparatus 10 according to the first embodiment of the present invention. The DTMF signal detection device 10 performs decoding of an audio codec when the received audio signal is a digital audio signal, and performs sampling to obtain sampling data such as PCM (Pulse Code Modulation) when the audio signal is an analog audio signal. .., 11n to be converted and frequency analysis means 12a, 12b,... For analyzing the intensity of the frequency used in the DTMF signal with respect to the sampling data output from the audio signal receiving means 11. 12n.

  The DTMF signal detection apparatus 10 further determines the type of DTMF signal received from the intensity of the frequency analyzed by the frequency analysis means 12, and the determination result of the DTMF signal determination means 13a, 13b, ..., 13n and the DTMF signal determination means 13. A frequency analysis control unit 14 for controlling the operation of the frequency analysis unit 12 based on (this is called DTMF signal detection information) is also provided. Here, the audio signal receiving unit, the frequency analyzing unit, and the DTMF signal determining unit exist for each communication session (n systems, n is an integer of 1 or more), and these are collectively referred to as the audio signal receiving unit 11. These are called frequency analysis means 12 and DTMF signal determination means 13.

  FIG. 2 is an explanatory diagram showing a more detailed configuration for one session of the frequency analysis means 12 shown in FIG. The frequency analysis unit 12 includes a sampling data receiving unit 21 that receives the sampling data output from the audio signal receiving unit 11, and each frequency used in the DTMF signal included in the data of a certain period extracted from the received sampling data. Frequency intensity analyzers 22a, 22b,..., 22m (m system, m is an integer of 1 or more, and these are hereinafter collectively referred to as frequency intensity analyzer 22).

  The frequency analysis unit 12 further includes an analysis result transmission unit 23 that transmits a frequency intensity analysis result by the frequency intensity analysis unit 22 to the DTMF signal determination unit 13 and a frequency intensity analysis unit 22 based on an instruction from the frequency analysis control unit 14. Is also provided with a control communication unit 24 for instructing a start time and an end time of frequency intensity analysis.

  The instruction from the frequency analysis control means 14 to the frequency analysis means 12 is composed of the frequency intensity analysis frequency and length, and the control communication unit 24 sends the start time and end to each frequency intensity analysis unit 22 based on this instruction. Specify the time. For example, when there is an instruction “frequency 10 ms, length 20 ms” from the frequency analysis control means 14, the control communication unit 24 sends “start time 0 ms end time 20 ms”, “ "Start time 10ms End time 30ms", ... At this time, the control communication unit 24 instructs the start time and the end time so that the start time and the end time of each frequency intensity analysis unit 22 do not overlap.

  FIG. 3 shows the frequency intensity analysis instructed by the control communication unit 24 to the frequency intensity analysis units 22a and 22b when the frequency analysis unit 12 shown in FIG. It is explanatory drawing which shows the example of start time and end time. In this example, the instruction from the frequency analysis control means 14 is “frequency 10 ms, length 20 ms”. On the other hand, the control communication unit 24 assumes that the frequency intensity analysis cycle differs by 10 ms, and the start time and end time are There are no duplicates.

  FIG. 4 is a table showing the frequency of the DTMF signal analyzed by each frequency intensity analysis unit 22 in the frequency analysis unit 12 shown in FIG. The frequency intensity analyzers 22a, 22b,..., 22h analyze the intensities of the eight frequencies shown in FIG. 4 with respect to the sampling data between the start time and the end time instructed from the control communication unit 24.

  As described above, the specification of the DTMF signal is ITU-T Q.264. 24, and one frequency is selected from 697 Hz, 770 Hz, 852 Hz, and 941 Hz that are low group frequencies, and one frequency is selected from 1209 Hz, 1336 Hz, 1447 Hz, and 1644 Hz that are high group frequencies, and sine waves of those frequencies And 16 types of signals are represented.

  The DTMF signal determination means 13 can detect the type (0-9, *, #, AD) of the button pressed by the operator by analyzing the signal frequency. For example, a combination of 697 Hz and 1209 Hz sine waves represents “1”, and a combination of 941 Hz and 1477 Hz represents “#”.

  The intensity of each frequency signal can be obtained by performing discrete cosine transform on the sampling data. In general, the Goertzel algorithm described in Patent Document 1 is used.

  Note that eight types of frequencies shown in FIG. 4 are used for the DTMF signal, but the frequency may be changed or added. Even in such a case, it is possible to cope with this by simply changing the frequency for analyzing the intensity by the frequency intensity analyzing unit 22.

  FIG. 5 is an explanatory diagram showing an example of a frequency determination method in the DTMF signal determination means 13 shown in FIG. The DTMF signal determination means 13 determines whether or not a DTMF signal has been received and the type of the DTMF signal from the analysis result of the frequency intensity with respect to the sampling data between the start time and the end time output from the frequency analysis means 12. Then, DTMF signal detection information is output.

  When the DTMF signal is included in the audio signal, the intensity of the frequency of each of the low group and the high group becomes extremely large as in the example shown in FIG. Using this property, the DTMF signal determination means 13 sets a threshold value for the intensity of the frequency, and determines that the DTMF signal has been received when the intensity of each of the low group and the high group exceeds the threshold value. FIG. 5 shows an example of a DTMF signal determination method by the DTMF signal determination means 13, and other determination methods may be used.

  FIG. 6 is a block diagram showing the configuration of the frequency analysis control means 14 shown in FIG. The frequency analysis control unit 14 receives the determination result reception unit 31 that receives the DTMF signal detection information from the DTMF signal determination unit 13, and determines that the DTMF signal detection information received by the determination result reception unit 31 is stored as the DTMF signal detection state table 35. A result storage unit 32; a frequency analysis accuracy determination unit 33 that determines frequency analysis accuracy based on the DTMF signal detection information received by the determination result reception unit 31 and the information stored in the DTMF signal detection state table 35; An instruction transmission unit 34 is configured to transmit an instruction of frequency intensity analysis frequency and length to the frequency analysis unit 12 according to the analysis accuracy determined by the accuracy determination unit 33.

  FIG. 7 is an explanatory diagram showing more detailed contents of the DTMF signal detection state table 35 shown in FIG. The DTMF signal detection state table 35 includes data items such as a session ID 35a, a status 35b, a detection start time 35c, and a detection end time 35d. The session ID 35a is an ID uniquely given to each session. The status 35b indicates the state of each session and stores “not detected” or “being detected”. In the case of “detecting”, the type of the detected DTMF signal (that is, the type of the key pressed by the user) is also saved. In the example shown in FIG. 7, the type of the detected DTMF signal is shown as (5) in parentheses.

  In the detection start time 35c and the detection end time 35d, when the status 35b is “not detected”, the detection start time and the detection end time of the DTMF signal received immediately before are stored. If no DTMF signal has been received after the session has started, both the detection start time 35c and the detection end time 35d are blank. On the other hand, when the status 35b is “detecting”, the detection start time of the currently detected DTMF signal is stored at the detection start time 35c, and the detection end time 35d is blank.

  An analysis accuracy determination method in the frequency analysis accuracy determination unit 33 of the frequency analysis controller 14 will be described. The accuracy of frequency intensity analysis by discrete cosine transform improves as the number of data used for analysis increases. When the status 35b is “not detected”, since the type and timing of the DTMF signal to be transmitted next is unknown, the frequency analysis accuracy determination unit 33 can analyze the frequency of the DTMF signal with high accuracy. Increase frequency and length. Such an operating state of the frequency analyzing means 12 is referred to as a high accuracy mode.

  On the other hand, when the status 35b is “being detected”, it is only necessary to determine whether or not the same DTMF signal is continued. Therefore, the analysis frequency can be lowered and the length can be shortened. Such an operating state of the frequency analysis means 12 is referred to as a low accuracy mode.

  The frequency and length of each of the high accuracy mode and the low accuracy mode are set in advance in the frequency analysis accuracy determination unit 33. Further, the threshold used by the DTMF signal determination unit 13 and the determination algorithm may be changed in the high accuracy mode and the low accuracy mode.

  FIG. 8 is a flowchart showing the operation of the DTMF signal detection apparatus 10 shown in FIG. First, after a call session starts, the audio signal receiving unit 11 starts receiving an audio signal from the communication destination terminal, converts the received audio signal into sampling data such as PCM, and passes it to the frequency analyzing unit 12 (step S101). .

  Receiving this, the frequency analysis means 12 calculates the start time and end time of each frequency intensity analysis based on the frequency and frequency of frequency analysis instructed from the frequency analysis control means 14 by the control communication unit 24, The frequency intensity analyzer 22 is instructed to perform frequency analysis (step S102). Upon receiving the instruction, the frequency strength analysis unit 22 analyzes the frequency strength of the received voice signal, and passes the analysis result from the analysis result transmission unit 23 to the DTMF signal determination means 13. The DTMF signal determination means 13 determines the presence and type of a DTMF signal from the analysis result of the received frequency intensity (step S103).

  Following this, the DTMF signal determination means 13 passes the DTMF signal detection information as the determination result to the frequency analysis control means 14. The frequency analysis control means 14 determines the frequency analysis accuracy from the received DTMF signal detection information (step S104). At the same time, the determination result reception unit 31 of the frequency analysis control unit 14 updates the DTMF signal detection state table 35 of the determination result storage unit 32 based on the received DTMF signal detection information.

  FIG. 9 is a table showing an operation in which the determination result receiving unit 31 updates the DTMF signal detection state table 35 in step S104 of FIG. If the status 35b is “not detected” and the DTMF signal detection information is “detected”, the determination result receiving unit 31 sets the status 35b to “detecting” and sets the detection start time 35c to start the frequency intensity analysis in step S102. The DTMF signal detection state table 35 is updated as time.

  If the status 35b is “detecting” and the DTMF signal detection information is “not detected”, the determination result receiving unit 31 sets the status 35b to “not detected” and sets the detection end time 35d to the frequency intensity in step S102. The DTMF signal detection state table 35 is updated as the analysis end time. In other cases, the determination result receiving unit 31 does not update the DTMF signal detection state table 35.

  In step S104, the frequency analysis accuracy determination unit 33 of the frequency analysis control unit 14 selects the high accuracy mode when the status 35b is “not detected” and the low accuracy mode when the status 35b is “detecting”, respectively. The frequency and length of frequency intensity analysis are instructed according to the mode selected from the instruction transmission unit 34.

  The above steps S101 to S104 continue repeatedly while the session continues, and the process ends when the session is disconnected (step S105).

(A more specific example of the first embodiment)
Next, a more specific example of the present embodiment will be described. FIG. 10 is an explanatory diagram showing a more specific configuration of the DTMF signal detection apparatus 10 shown in FIG. The DTMF signal detection apparatus 10 is realized by a server apparatus 110 including a network interface 111 (LAN port), a CPU (Central Processing Unit, main arithmetic control means) 112, and an external storage device 113 (hard disk drive or the like).

  The audio signal receiving means 11a, 11b,..., 11n are realized by a program executed by the CPU 112 controlling the network interface 111. The server apparatus 110 is connected to a plurality of IP (Internet Protocol) telephones 121a, 121b,... Via a network interface 111 and an IP network 122.

  The IP telephones 121a, 121b,... Convert analog voice signals including call voices and DTMF signals into digital signals. The data is encoded using a codec such as H.711, and a RTP (Real-time Transport Protocol) header is added to the server device 110 (DTMF signal detection device 10) via the network 112.

  Further, the IP telephones 121a, 121b,... Can be replaced with a set of a normal analog telephone 131a and a conversion device 132. In this case, the analog audio signal output from the analog telephone 131a is converted into a digital signal to which the encoding and RTP header is added by the conversion device 132 by the same processing as described above, and then the server device 110 ( Transmit to the DTMF signal detector 10). That is, it can be said that the functions of the IP telephones 121a, 121b,..., 121n are divided into the analog telephone 131a and the conversion device 132. The conversion device 132 is generally called a “VoIP adapter”.

  Further, an analog voice signal output from the analog telephone 131b is connected to the server apparatus 110 (DTMF signal detection apparatus 10) via an analog telephone network 133 different from the IP network without using an IP telephone or a conversion apparatus. You can also. In this case, the analog telephone 131b is connected to the audio signal receiving unit 11 via the audio interface 114 instead of the network interface 111.

  .., 12n, DTMF signal determination means 13a, 13b,..., 13n, and frequency analysis control means 14 (except for the DTMF signal detection state table 35) are all executed by the CPU 112. It is a program. The sampling data receiving unit 21, the frequency intensity analyzing units 22a, 22b,..., 22h, the analysis result transmitting unit 23, and the control communication unit 24 of the frequency analyzing unit 12 are all programs executed by the CPU 112. It is an internal module.

  Among the frequency analysis control means 14, the determination result reception unit 31, the determination result storage unit 32, the frequency analysis accuracy determination unit 33, and the instruction transmission unit 34 are internal modules of the frequency analysis control means 14 that are programs executed by the CPU 112. The DTMF signal detection state table 35 is stored in the external storage device 113.

  Further, the frequency analysis means 12 can be replaced with hardware for performing frequency analysis. In that case, an expansion board that performs frequency analysis is mounted on the DTMF signal detection device 10 that is a server device, and the sampling data reception unit 21, the analysis result transmission unit 23, and the control communication unit 24 are all buses to the server device 10. The frequency intensity analysis unit 22 is a DSP (Digital Signal Processor) for frequency analysis.

  When the server device 110 starts a session (referred to as session A) with one of the telephones connected via the network, the audio signal receiving means 11 corresponding to the session A, the frequency Analysis means 12 and DTMF signal determination means 13 are determined. Here, the audio signal receiving unit 11a, the frequency analyzing unit 12a, and the DTMF signal determining unit 13a are used for the session A, respectively.

  Next, the frequency analysis control unit 14 instructs the frequency analysis unit 12a on the frequency and length of the frequency intensity analysis. In the present embodiment, “high frequency is 5 ms and length is 20 ms” in the high accuracy mode, and “frequency is 10 ms and length is 10 ms” in the low accuracy mode. Since the operation is performed in the “high accuracy mode” at the start of the session A, the frequency analysis control unit 14 instructs the frequency analysis unit 12a to perform the operation at “frequency 5 ms, length 20 ms”.

  The audio signal receiving unit 11a receives an RTP (Real-Time Transport Protocol) packet in which audio data is stored from a communication destination terminal, and determines which one based on information (IP address and port number) of the IP header and UDP header. After identifying whether the packet is a session packet, the packet is rearranged and the lost packet is restored based on the information of the RTP header. The audio codec such as 711 is decoded to be converted into 8 kHz sampling data and transmitted to the frequency analysis means 12a.

  When starting reception of sampling data, the control communication unit 24 of the frequency analysis unit 12a operates the four frequency intensity analysis units 22a to 22d in the CPU 112, and the start time and the end time of frequency intensity analysis for each of them. Instruct. FIG. 11 shows a frequency intensity analysis operation that the control communication unit 24 instructs each frequency intensity analysis unit 22a to 22d in the server apparatus 110 that is a specific example of the DTMF signal detection apparatus 10 shown in FIG. It is explanatory drawing.

  Based on the instruction from the control communication unit 24, the frequency intensity analysis units 22a to 22d perform a discrete cosine transform operation of the sampling data at the specified start time and end time, and calculate the intensity of each frequency used in the DTMF signal. The analysis result is passed to the DTMF signal determination means 13 via the analysis result transmission unit 23.

  The DTMF signal determination means 13 extracts, for each of the results received from the frequency intensity analysis units 22a to 22d, the frequencies whose intensity exceeds the threshold value, and there is one low group and one high group. In each case, it is determined that the signal is a DTMF signal, and the determination result (DTMF signal detection information) is passed to the frequency analysis control means 14.

  When the determination result receiving unit 31 receives the DTMF signal detection information from the DTMF signal determination unit 13, the frequency analysis control unit 14 updates the DTMF detection state table 35 as necessary using the determination result storage unit 32. At the start of session A, in the DTMF detection status table 35, the status 35b is “not detected”, the detection start time 35c and the detection end time 35d are both blank, and this DTMF detection status table until the DTMF signal is detected. 35 is never updated.

  Here, the operation when the DTMF signal is detected will be described. FIG. 12 is an explanatory diagram showing an operation when a DTMF signal is detected in the operation of the frequency intensity analysis by the frequency intensity analysis units 22a to 22d shown in FIG. The example shown in FIG. 12 shows an example in which the frequency intensity analyzer 22a, which is one of the frequency intensity analyzers, has detected a DTMF signal as a result of frequency analysis at timing (1). The timing at which the DTMF signal is detected is shown as a vertical broken line.

  The determination result receiving unit 31 of the frequency analysis control unit 14 that has received the report of the DTMF signal “detected” from the frequency intensity analysis unit 22 a via the DTMF signal determination unit 13 a is stored in the DTMF detection state table 35 by the determination result storage unit 32. The status 35b is “detecting”, the detection start time 35c is the detection start time of the currently detected DTMF signal, that is, the time of the vertical broken line in FIG. 12, and the detection end time 35d is blank. FIG. 13 is an explanatory diagram showing an example of the DTMF detection state table 35 in which the DTMF signal corresponding to “7” is detected and updated by the frequency intensity analysis by the frequency intensity analysis unit 22a shown in FIG.

  Subsequently, the frequency analysis accuracy determination unit 33 instructs the frequency analysis means 12a to operate in the low accuracy mode “frequency 10 ms, length 10 ms”. In response to this instruction, the control communication unit 24 of the frequency analyzing means 12a stops the operation of the frequency intensity analyzing units 22b to 22d that have been operating until then, and only the frequency intensity analyzing unit 22a has a frequency of 10 ms and a length of 10 ms. The start time and end time of the frequency intensity analysis are instructed so as to continue the operation.

  This analysis result is transmitted to the DTMF signal determination means 13a, and the determination result is transmitted to the frequency analysis control means 14. When the DTMF signal determination unit 13a determines that the same DTMF signal is continuously received, the instruction from the frequency analysis control unit 14 to the frequency analysis unit 12a is not changed.

  Here, the operation when the DTMF signal is no longer detected will be described. In the example illustrated in FIG. 12, when the frequency intensity analysis unit 22a performs the frequency analysis at the timing (2) and the DTMF signal is “not detected”, the determination result reception unit 31 of the frequency analysis control unit 14 determines The result storage unit 32 sets the status 35b of the DTMF detection state table 35 to “not detected” and the detection end time 35d as the end time of the frequency intensity analysis. FIG. 14 is an explanatory diagram illustrating an example of the DTMF detection state table 35 in which the DTMF signal is updated to “not detected” in the frequency intensity analysis by the frequency intensity analysis unit 22a illustrated in FIG.

  Subsequently, the frequency analysis accuracy determination unit 33 instructs the frequency analysis means 12a to operate at “frequency 5 ms, length 20 ms” in the high accuracy mode. Upon receiving this instruction, the control communication unit 24 of the frequency analyzing means 12a instructs the frequency analyzers 22a to 22d to start time and end time of the frequency intensity analysis so as to be “frequency 5 ms, length 20 ms”. . FIG. 15 is an explanatory diagram showing an operation after the DTMF signal is no longer detected in the frequency intensity analysis by the frequency intensity analysis units 22a to 22d shown in FIG. In FIG. 15, the timing at which the DTMF signal is no longer detected is shown as a vertical alternate long and short dash line.

  As described above, the DTMF signal detection apparatus 10 according to the present embodiment and the server apparatus 110 that is a specific example thereof determine whether or not high-accuracy frequency analysis is necessary from the reception status of the DTMF signal. In a situation where high-accuracy frequency analysis is not necessary, the number of frequency analyzers that are simultaneously operated is reduced.

  More specifically, when a new DTMF signal is detected, it is necessary to specify a frequency for an unknown input signal, so that the operation of the four frequency analysis units is necessary as the “high accuracy mode”. On the other hand, when detecting whether or not the same DTMF signal continues, the frequency is known, and therefore, only one frequency analysis unit needs to be operated as the “low accuracy mode”.

  As a result, the resources of the frequency analyzer that no longer needs to be operated can be directed to other sessions. Therefore, it is possible to increase the number of sessions that can be operated simultaneously by detecting the DTMF signal.

(Overall operation of the first embodiment)
Next, the overall operation of the above embodiment will be described.
In the DTMF signal detection method according to the present embodiment, the type of the DTMF signal detected by detecting the presence or absence of a DTMF (Dual-Tone Multi-Frequency) signal composed of two different frequency components from the input audio signal is determined. In the output DTMF signal detection device 10, the frequency analysis means analyzes the intensity of each use frequency predetermined as the standard of the DTMF signal in the audio signal (FIG. 8, steps S101 to S102). Based on the analysis result, the DTMF signal determining means determines the presence or absence of the DTMF signal included in the audio signal and the type of the DTMF signal and outputs them (step S103 in FIG. 8), and according to the determination result of the DTMF signal determining means. The frequency analysis control means instructs to suppress the operation of the frequency analysis means (step S104 in FIG. 8).

Here, each of the above operation steps may be programmed so as to be executable by a computer, and these may be executed by the DTMF signal detection apparatus 10 that directly executes each of the steps. The program may be recorded on a non-temporary recording medium, such as a DVD, a CD, or a flash memory. In this case, the program is read from the recording medium by a computer and executed.
By this operation, this embodiment has the following effects.

  According to the present embodiment, the analysis accuracy required for the DTMF signal is determined from the reception status of the DTMF signal, and an operation mode corresponding to this is instructed to the frequency analysis unit. As a result, when the operation of the “high accuracy mode” is not required, the operation of the frequency analysis unit is set to the “low accuracy mode”, and it is possible to reduce the resources of the operating frequency analyzer, so that the reduction is achieved. It is possible to allocate the resources for the other sessions, and therefore it is possible to increase the number of sessions that can operate simultaneously by detecting the DTMF signal.

(Second Embodiment)
In the DTMF signal detection apparatus 150 according to the second embodiment of the present invention, in addition to the configuration of the first embodiment, the frequency analysis control means 154 does not detect the DTMF signal currently detected by the DTMF signal determination means 13. When the elapsed time from the detection end time immediately before the DTMF signal is equal to or less than a predetermined value, the frequency analysis means is instructed to suppress the detection accuracy of the DTMF signal.

With this configuration, in addition to obtaining the same effect as in the first embodiment, it is possible to further increase the time during which the frequency analysis means is operated in the operation with low detection accuracy of the DTMF signal (low accuracy mode). As a result, the number of sessions that can be operated simultaneously can be increased by detecting the DTMF signal as compared with the first embodiment.
Hereinafter, this will be described in more detail.

  FIG. 16 is an explanatory diagram showing the configuration of the DTMF signal detection apparatus 150 according to the second embodiment of the present invention. The configuration of the DTMF signal detection device 150 is exactly the same as that of the DTMF signal detection device 10 according to the first embodiment described above in terms of hardware, and the frequency analysis control means 14 is another frequency analysis control means in terms of software. 154 has been replaced. Since the other elements are the same as those of the DTMF signal detection apparatus 10, they are referred to by the same name and reference number.

  FIG. 17 is an explanatory diagram showing a more detailed configuration of the frequency analysis control means 154 shown in FIG. The frequency analysis control unit 154 is the same as the frequency analysis control unit 14 according to the first embodiment described above except that the frequency analysis accuracy determination unit 33 is replaced with another frequency analysis accuracy determination unit 163. Since the other elements are the same as those of the DTMF signal detection apparatus 10, they are referred to by the same name and reference number.

  The frequency analysis accuracy determination unit 163 illustrated in FIG. 17 includes the frequency analysis unit 12 according to whether the frequency analysis accuracy determination unit 33 according to the first embodiment determines that the status 35b of the DTMF detection state table 35 is “not detected” or “detected”. In addition to switching between the high-accuracy mode and the low-accuracy mode, the frequency analysis means 12 is switched between the high-accuracy mode and the low-accuracy mode using the above-described DTMF rules.

As mentioned above, ITU-T Q.I. 24 defines the DTMF signal as follows (in the case of the NTT system).
(1) The minimum duration of the DTMF signal is 40 ms (the DTMF signal needs to be continuously transmitted for 40 ms or more)
(2) Maximum interruption time is 10 ms (even if there is an interruption of 10 ms or less, it is necessary to treat it as the same signal)
(3) The minimum pause time between DTMF signals is 30 ms (it is necessary to put a pause of at least 30 ms between two DTMF signals)
(4) Signal speed is 120 ms / digit (transmission time of one signal + pause time needs to be 120 ms or more)

  According to the rule (3) above, a new DTMF signal is not transmitted for at least 30 ms after the DTMF signal is stopped. Accordingly, it is only necessary to confirm that the DTMF signal is not received within the time within 30 ms from the detection end time when the status is “not detected”, so that the low accuracy mode can be set.

  Further, according to the regulation (4), there is a minimum interval of 120 ms from the start of transmission of the DTMF signal to the start of transmission of the next DTMF signal. Accordingly, the low-accuracy mode can be set even when the status 35b is “not detected” and the time is within 120 ms from the detection start time.

  Therefore, the frequency analysis accuracy determination unit 33 according to the first embodiment instructs the frequency analysis unit 12 to operate in the “low accuracy mode” only when the status 35b is “detecting”. In this embodiment, even if the status 35b changes from “detecting” to “not detected”, the operation in the “low accuracy mode” is performed on the frequency analysis means 12 only during a predetermined time from the detection end time or the detection start time. Since it is continued, the time during which the frequency analysis means 12 operates in the low accuracy mode can be made longer. Accordingly, it is possible to process a larger number of sessions at the same time than in the first embodiment.

(Third embodiment)
In addition to the configuration of the first embodiment, the DTMF signal detection device 210 according to the third embodiment of the present invention includes a voice including information on options that can be input by the user from the voice guidance transmission device 220 provided separately. When the option reproduction information indicating that the state is the state before sending the guidance is received, the frequency analysis unit is instructed to suppress the detection accuracy of the DTMF signal.

With this configuration, in addition to obtaining the same effects as those of the first and second embodiments, it is possible to further increase the time during which the frequency analysis means is operated in a low detection accuracy mode (low accuracy mode) of the DTMF signal. Therefore, it is possible to increase the number of sessions that can be operated simultaneously by detecting the DTMF signal as compared with the first and second embodiments.
Hereinafter, this will be described in more detail.

  FIG. 18 is an explanatory diagram showing the configuration of the automatic voice response apparatus 201 according to the third embodiment of the present invention. The automatic voice response device 201 includes a DTMF signal detection device 210 that detects a DTMF signal from an input voice signal, a processing device 230 that performs processing according to the type of the detected DTMF signal, and an instruction from the processing device 230. A voice guidance transmission device 220 that transmits a corresponding voice guidance signal to the caller telephone, and a communication device 240 that receives the voice signal (including the DTMF signal) from the caller telephone and transmits the voice guidance signal. Composed.

  The voice guidance transmission device 220 transmits a voice guidance signal according to an instruction from the processing device 230 via the communication device 240 and simultaneously notifies the DTMF signal detection device 210 of information on the voice guidance signal being transmitted. The communication device 240 passes the audio signal (including the DTMF signal) received from the caller telephone set to the DTMF signal detection device 210.

  FIG. 19 is an explanatory diagram showing a more detailed configuration of the DTMF signal detection device 210 shown in FIG. The DTMF signal detection apparatus 210 generally has the same configuration as the DTMF signal detection apparatus 10 according to the first embodiment shown in FIG. The difference is that the frequency analysis control means 14 is replaced with another frequency analysis control means 214. Since the other elements are the same as those of the DTMF signal detection apparatus 10, they are referred to by the same name and reference number.

  FIG. 20 is an explanatory diagram showing a more detailed configuration of the frequency analysis control means 214 shown in FIG. The frequency analysis control unit 214 includes a guidance information receiving unit 236 that receives information about the voice guidance signal transmitted from the voice guidance transmitting device 220. Further, the frequency analysis accuracy determination unit 33 is replaced with another frequency analysis accuracy determination unit 233.

  The frequency analysis accuracy determination unit 233 determines the frequency analysis accuracy based on the information received from the guidance information reception unit 236 in addition to the information from the determination result reception unit 31 and the determination result storage unit 32. Since the other elements are the same as those of the frequency analysis control unit 14 according to the first embodiment, they are referred to by the same name and reference number.

  FIG. 21 is a flowchart showing the operation of the DTMF signal detection apparatus 210 shown in FIG. The operation shown in FIG. 21 is substantially the same as that of the DTMF signal detection apparatus 10 shown in FIG. 8, but the frequency analysis control means 214 (frequency analysis accuracy determination unit 233) determines the frequency analysis accuracy (step) S304) Only the operation is different from FIG. The other operations are the same as those in FIG.

  FIG. 22 is a table showing details of the operation of the frequency analysis control unit 214 (frequency analysis accuracy determination unit 233) determining the frequency analysis accuracy shown in step S304 of FIG. The frequency analysis accuracy determination unit 233 is a frequency instructed to the frequency analysis unit 12 from the option reproduction information received from the guidance information reception unit 236 and the DTMF signal detection information received from the DTMF signal determination unit 13 by the determination result reception unit 31. The analysis accuracy is selected and selected from “high accuracy mode” and “low accuracy mode”.

  The option reproduction information is information received by the guidance information receiving unit 236 from the voice guidance transmission device 220, and has two values “unreproduced” or “reproduced”. “Non-reproduced” means that the voice guidance transmitting apparatus 220 has not yet transmitted the voice information about the option selected by the user with the operation button. “Reproduced” means that the audio information has already been transmitted.

  As in the DTMF signal detection apparatus 10 of the first embodiment, the DTMF signal detection information has two values of whether the DTMF signal is “not detected” or “detected”. If the option reproduction information is “unreproduced”, the frequency analysis accuracy determination unit 233 selects the “low accuracy mode” regardless of the DTMF signal detection information. If the option reproduction information is “reproduced” and the DTMF signal detection information is “not detected”, the frequency analysis accuracy determination unit 233 selects “high accuracy mode”, and the option reproduction information is “reproduced” and DTMF. If the signal detection information is “detected”, the frequency analysis accuracy determination unit 233 selects the “low accuracy mode”.

  In the DTMF signal detection apparatus 10 of the first embodiment, the high accuracy mode is set when the DTMF signal is “not detected”, and the low accuracy mode is set when the DTMF signal is “detecting”. However, when the option is “unreproduced”, a DTMF signal is not input unless the terminal (user) knows the option in advance. Therefore, in the present embodiment, even when the DTMF signal is “not detected” and the option is “not reproduced”, the operation of the frequency analysis unit 12 can be set to the low accuracy mode.

  Therefore, in this embodiment, it is possible to increase the time during which the frequency analysis unit 12 operates in the low-accuracy mode by using the option reproduction information received from the voice guidance transmission device 220 as compared with the first embodiment. . Although DTMF signal detection apparatus 10 in the present embodiment is described as receiving option reproduction information from voice guidance transmission apparatus 220, it may be received from another device.

(A more specific example of the third embodiment)
Next, a more specific example of the present embodiment will be described. The automatic voice response device 201 is configured by connecting a DTMF signal detection device 210 that is a server device, a voice guidance transmission device 220, a processing device 230, and a communication unit 240 to each other via Ethernet (registered trademark). Can do. Each element of the DTMF signal detection device 210 can be configured by a computer program executed by the CPU 112, similarly to the DTMF signal detection device 10 of the first embodiment.

  FIG. 23 is a time chart showing the frequency analysis accuracy determined by the DTMF signal detection device 210 in the automatic voice response device 201 shown in FIG. FIG. 23 shows the contents of the voice guidance transmitted from the voice guidance transmission device 220, the option reproduction information notified from the voice guidance device 220 to the DTMF signal detection device 210, and the frequency analysis accuracy determination unit 233 determining it accordingly. The frequency analysis accuracy is shown.

  First, the voice guidance device 220 sends a prior explanation message about the first question at times t0 to t1, sends the first option of the first question at times t1 to t2, and the first option at times t2 to t3. The second and subsequent choices of one question are sent out as voice guidance. Thereafter, the voice guidance device 220 temporarily pauses the voice guidance at times t3 to t4, and then continues the second and subsequent questions in the same manner from time t4.

  In this case, in the state where the option is not transmitted at all, there is almost no possibility that the operator presses the button in the option and inputs the DTMF signal to the automatic voice response device 201. After the first option of the first question is sent, there is a possibility that the user who is trying to select the first option inputs the DTMF signal of the option.

  Accordingly, at this time, the option reproduction information notified from the voice guidance device 220 to the DTMF signal detection device 210 is “unreproduced” at the time t0 to t2, and the times t2 to t4 after the first option is transmitted. Becomes “Reproduced”. Therefore, the frequency analysis accuracy determined by the frequency analysis accuracy determination unit 233 is the “low accuracy mode” for the times t0 to t2. At times t2 to t4, the “high accuracy mode” or the “low accuracy mode” is selected by the same operation as in the first embodiment. After time t4, the second and subsequent questions continue in the same manner.

  According to the present embodiment described above, the frequency analysis unit 12 can be operated in the “low accuracy mode” in accordance with the option reproduction information notified from the voice guidance device 220. Therefore, the first and second implementations The time during which the frequency analysis means 12 operates in the “low-accuracy mode” can be further increased as compared with the mode. Accordingly, it is possible to process a larger number of sessions at the same time than in the first and second embodiments.

(Fourth embodiment)
In the DTMF signal detection apparatus 310 according to the fourth embodiment of the present invention, in addition to the configuration of the first embodiment, the frequency analysis unit 312 includes a DTMF signal storage unit 325 that stores DTMF signals input in the past. And the frequency analysis control means 314 instructs the frequency analysis means 312 to operate intermittently while suppressing the detection accuracy of the DTMF signal, and the DTMF signal determination means 313 is the same as the previous operation of the frequency analysis means. When it is detected that the DTMF signal has changed from the current operation, the frequency analysis means 312 does not suppress the detection accuracy of the DTMF signal input in the time zone when the change of the DTMF signal is detected. Was configured to direct the analysis.

With this configuration, in addition to obtaining the same effect as in the first embodiment, it is possible to create a time zone in which the frequency analysis means is not operated at all. Therefore, it is possible to detect a DTMF signal further than in the first embodiment. It is possible to increase the number of sessions that can be operated simultaneously.
Hereinafter, this will be described in more detail.

  FIG. 24 is an explanatory diagram showing the configuration of the DTMF signal detection apparatus 310 according to the fourth embodiment of the present invention. The configuration of the DTMF signal detection device 310 is completely the same as that of the DTMF signal detection device 10 according to the first embodiment described above in hardware, and the frequency analysis means 12, the DTMF signal determination means 13, and the frequency are also in software. The analysis control means 14 is replaced with separate frequency analysis means 312, DTMF signal determination means 313, and frequency analysis control means 314, respectively. Since the other elements are the same as those of the DTMF signal detection apparatus 10, they are referred to by the same name and reference number.

  FIG. 25 is an explanatory diagram showing a more detailed configuration of the frequency analysis means 312 shown in FIG. The frequency analysis means 312 includes a DTMF signal storage unit 325 that stores the DTMF signal received by the sampling data reception unit 21 for a predetermined time, and the frequency intensity analysis unit 22 receives a command from the control communication unit 24. Accordingly, it is replaced with another frequency intensity analysis unit 322 (322a, 322b,...) Capable of reading the DTMF signal stored in the DTMF signal storage unit 325 and analyzing the DTMF signal. Except this point, it is the same as the frequency analysis means 312 according to the first embodiment described above.

  FIG. 26 is an explanatory diagram showing a more detailed configuration of the frequency analysis control means 314 shown in FIG. The frequency analysis control unit 314 is the same as the frequency analysis control unit 14 according to the first embodiment described above except that the frequency analysis accuracy determination unit 33 is replaced with another frequency analysis accuracy determination unit 333. Since the other elements are the same as those of the DTMF signal detection apparatus 10, they are referred to by the same name and reference number.

  The frequency analysis accuracy determination unit 333 first operates the frequency analysis unit 312 in the low accuracy mode at the start of operation. In the low-accuracy mode, the operation of the frequency analysis unit 312 is stopped at a constant period to create a time zone during which frequency intensity analysis is not performed. That is, the frequency analysis means 312 is operated intermittently. Hereinafter, this will be described in more detail.

  FIG. 27 is a time chart showing the operation of the DTMF signal detection apparatus 310 shown in FIGS. The horizontal axis in FIG. 27 indicates time. Let the start time be t0, and the elapsed time from there be t1, t2, t3,. The frequency analysis control means 314 is a DTMF signal that is inputted in real time in the low-precision mode in real time in the time zones of times t0 to t1, t2 to t3, t4 to t5, t6 to t7,. This is the time period for the analysis.

  The frequency analysis control means 314 then receives the DTMF signal that is input to the frequency analysis means 312 in real time at other times t1 to t2, t3 to t4, t5 to t6, t6 to t7,. This is a time period during which no analysis is performed. FIG. 28 is a flowchart showing the operation of the DTMF signal detection apparatus 310 shown in FIGS.

  When a session is generated, the frequency analysis accuracy determination unit 333 of the frequency analysis control unit 314 first performs initialization for the operation mode of the frequency analysis unit 312. In the initial state, the frequency analysis means 312 is operated in the low accuracy mode (step S401), and the frequency is set to be greater than the length in the low accuracy mode.

  The definitions of “frequency” and “length” here are as described in paragraph 0033 and FIG. 3 of the present specification. That is, by setting the “frequency” longer than the “length”, the operation of the signal frequency analysis unit 312 is stopped and a time period in which the frequency analysis is not performed occurs. This is because the frequency analysis means 312 operates in the low accuracy mode at the times t0 to t1, t2 to t3, t4 to t5, t6 to t7,... Shown in FIG. The operation is to store the DTMF signal in the DTMF signal storage unit 325.

  The frequency analysis unit 312 performs frequency intensity analysis with the frequency and length as instructed from the frequency analysis accuracy determination unit 333 in step S401, and notifies the DTMF signal determination unit 13 of the intensity of each frequency (step S402). The DTMF signal determination means 313 determines the type of the DTMF signal from the notified intensity of each frequency, and outputs the result to the frequency analysis control means 314 (step S403).

  Then, the DTMF signal determination unit 313 determines whether or not the detection result of the DTMF signal in the current operation of the signal frequency analysis unit 312 is equal to the detection result of the DTMF signal in the previous operation (step S404). If the detection result of the DTMF signal in the current operation and the previous operation of the frequency analysis unit 312 is the same (No in step S404), the DTMF signal is changed in the time zone between the current operation and the previous operation. If not, the process proceeds to step S406 described later.

  If the detection results of the DTMF signal in the current operation and the previous operation are different (Yes in step S404), it is estimated that the DTMF signal has changed in the time zone between the current operation and the previous operation, and the DTMF signal The DTMF signal determination means 313 performs frequency analysis control means so as to additionally analyze the DTMF signal stored in the storage unit 325 in the time zone in which it is estimated that the change has occurred (in this embodiment, this is referred to as a high accuracy mode). The frequency analysis means 312 is instructed via 314 (step S405). Receiving this instruction, the frequency analysis means 312 reads out the DTMF signal input in the instructed time zone from the DTMF signal storage unit 325 and analyzes it.

  The DTMF signal determination means 313 outputs the analysis result of the DTMF signal to the outside (step S406), and repeats the above processing while the session continues, and ends the processing when the session is disconnected. (Step S407). If it is determined in step S404 that the DTMF signal has not changed, “no change” in step S406, that is, the DTMF signal determination means 313 outputs the same determination result as the previous operation.

  In the example shown in FIG. 27, since no DTMF signal is detected in the time period from time t0 to t1 and from time t2 to t3, the DTMF signal is also detected in the time period from time t1 to t2. It can be judged that the state of being not continued. Further, since the DTMF signal corresponding to the signal type “1” is continuously detected in the time period from time t4 to t5 and from time t6 to t7, the same signal is also obtained in the time period from time t5 to t6. It can be determined that the type “1” DTMF signal has continued.

  On the other hand, the DTMF signal is not detected in the time period from time t2 to t3, and the DTMF signal “1” is detected in the time period from time t4 to t5. In this case, it cannot be determined whether the DTMF signal is detected or the DTMF signal “1” is detected in the time period from the time t3 to the time t4.

  Therefore, the DTMF signal determination means 313 instructs the frequency analysis means 312 via the frequency analysis control means 314 to read out from the DTMF signal storage unit 325 and analyze the DTMF signal input during this time period t3 to t4. To do. The DTMF signal determination means 313 can determine that the DTMF signal input in the time period from time t3 to t4 is “1” only after receiving the output of the frequency analysis means 312.

  As described above, when the DTMF signal changes, the high-accuracy mode operation of the frequency analysis unit 312 is necessary. However, when the same type of DTMF signal continues, the frequency analysis unit 312 is intermittently operated. The low-accuracy mode may be used to create a time zone during which it is not operated. As a result, it is possible to further reduce the resources of the operating frequency intensity analysis unit and further increase the number of sessions that can be operated simultaneously by detecting the DTMF signal.

  For this purpose, the frequency analysis means 312 is provided with a DTMF signal storage unit 325 that stores a DTMF signal for a predetermined time, and can analyze the DTMF signal retroactively. The storage capacity of the DTMF signal storage unit 325 only needs to be able to analyze the DTMF signal input in the time period from time t3 to t4 at time t4 to t5. It only has to be memorized.

  For the type of DTMF signal detected before that, the DTMF signal determination means 313 may have a function of storing the detection result at the previous operation of the frequency analysis means 312. In addition, since past detection results are stored in the DTMF signal detection state table 35 of the frequency analysis control means 314, the storage results may be read out via the frequency analysis control means 314.

(A more specific example of the fourth embodiment)
Next, a more specific example of the present embodiment will be described. FIG. 29 is an explanatory diagram showing a more specific configuration of the DTMF signal detection apparatus 310 shown in FIG. The DTMF signal detection device 310 is realized by a server device 510 having the same hardware configuration as the server device 110 which is a specific example of the first embodiment shown in FIG.

  The frequency analysis unit 312 illustrated in FIG. 25 is realized as a computer program executed by the CPU 112 of the server device 510. However, only the DTMF signal storage unit 325 of the frequency analysis unit 312 is realized as a storage area secured on the external storage device 113. The DTMF signal determination unit 313 and the frequency analysis control unit 314 execute only the DTMF signal detection state table 35 as a storage area on the external storage device 113, and the others are executed by the CPU 112, similarly to the server device 110 shown in FIG. Realized as a computer program.

  FIG. 30 is a time chart showing a more specific operation of the DTMF signal detection apparatus 310 shown in FIG. Here, the frequency analysis accuracy determination unit 333 determines the frequency as “20 ms” and the length as “10 ms” by the operation of the frequency analysis means 312 (step S401 in FIG. 28). That is, the frequency analysis unit 312 apparently has a non-operating time zone every 10 ms.

  That is, FIG. 30 is the same as FIG. 27 when t0 = 0, t1 = 10 ms, t2 = 20 ms,... And t3, t4, t5, t6, t7,. The DTMF signal storage unit 325 can store the DTMF signal input for one period of “frequency”, that is, the past 20 ms.

  The frequency analysis unit 312 that has started operating in the low-accuracy mode receives each frequency from the DTMF signal input from the audio signal reception unit 11 via the sampling data reception unit 21 at time t = t0 to t1 = 0 to 10 ms. DTMF signal determination means 313 is notified of the intensity of the signal. The DTMF signal determination means 313 performs DTMF signal determination from the intensity of each frequency. Here, since the DTMF signal was not particularly detected, the determination result at time t = t0 to t1 = 0 to 10 ms is “not detected” (steps S402 to 403 in FIG. 28).

  At this time, since there is no detection result of the DTMF signal in the previous operation, the DTMF signal determination means 313 outputs “not detected” and proceeds to the second round as it is in the flow of FIG. Steps S404-407).

  The frequency analysis means 312 does not operate at time t = t1 to t2 = 10 to 20 ms, and stores the input DTMF signal in the DTMF signal storage unit 325 as it is.

  The frequency analysis unit 312 obtains the intensity of each frequency for the DTMF signal input at time t = t2 to t3 = 20 to 30 ms, and notifies the DTMF signal determination unit 313 of it. The DTMF signal determination means 313 performs DTMF signal determination from the intensity of each frequency. Again, since no DTMF signal was detected, the determination result at time t = t2 to t3 = 20 to 30 ms is “not detected” (steps S402 to 403 in FIG. 28).

  Here, the DTMF signal determination means 313 compares the detection result of the DTMF signal in the previous operation with the current detection result (step S404 in FIG. 28). At this point in time, “not detected” remains unchanged, so the DTMF signal determination means 313 outputs “not detected” at times t1 to t2 = 10 to 20 ms, t2 to t3 = 20 ms to 30 ms, and 3 Proceed to the lap (FIG. 28, steps S406 to 407).

  The frequency analysis means 312 does not operate at time t = t3 to t4 = 30 to 40 ms, and stores the input DTMF signal in the DTMF signal storage unit 325 as it is. Then, the frequency analysis unit 312 obtains the strength of each frequency for the DTMF signal input at time t = t4 to t5 = 40 to 50 ms, and notifies the DTMF signal determination unit 313 of it.

  Here, the DTMF signal determination means 313 determines that the DTMF signal is “1”, and compares the detection result of the DTMF signal in the previous operation with the current detection result (step S404 in FIG. 28). At this time, since “not detected” is changed to “1”, it cannot be determined whether the time t = t3 to t4 = 30 to 40 ms is “not detected” or “1”. Therefore, the high-accuracy mode for analyzing the DTMF signal input at time t = t3 to t4 = 30 to 40 ms is instructed to the frequency analysis means 312 (step S405 in FIG. 28).

  The frequency analysis unit 312 reads out the DTMF signal input at time t = t3 to t4 = 30 to 40 ms from the DTMF signal storage unit 325, analyzes it, and reports the detected frequency to the DTMF signal determination unit 313. Here, since the frequency components of “697 Hz” and “1209 Hz” are detected, the DTMF signal determination means 313 determines that the signal type = “1”, and this is determined as a determination result at time t = t3 to t4 = 30 to 40 ms. It outputs (FIG. 28, step S406).

  Thereafter, “1” which is a determination result at time t = t4 to t5 = 40 to 50 ms is output.

  Here, the frequency analysis means 312 returns to the operation in the low-accuracy mode (step S401 in FIG. 28), does not operate at time t = t5 to t6 = 50 to 60 ms, and the input DTMF signal is used as it is. This is stored in 325 (FIG. 28, step S406). The frequency analysis means 312 obtains the intensity of each frequency for the DTMF signal input at time t = t6 to t7 = 60 to 70 ms, and notifies the DTMF signal determination means 313 (FIG. 28, steps S402 to 403). ).

  The DTMF signal determination means 313 performs DTMF signal determination from the intensity of each frequency. Here, since the DTMF signal having the same signal type = “1” as in the previous operation is detected, “1” is output as it is as the determination result at time t = t6 to t7 = 60 to 70 ms (FIG. 28, step S404). ˜406). Thereafter, until the end of the session, the DTMF signal detection device 310 repeats this operation in the same manner (FIG. 28, step S407).

  As described above, the frequency analysis unit 312 operates in the high accuracy mode only between the times t = t3 and t4 = 30 to 40 ms. For other times t = 0 to 10, 20 to 30, 40 to 50, and 60 to 70 ms, the frequency analysis unit 312 operates in the low accuracy mode.

  That is, since the frequency analysis means 312 operates in the low-accuracy mode except during the time period t = t3 to t4 = 30 to 40 ms where the judgment results before and after are different, resources necessary for frequency analysis are further suppressed. can do.

  In this DTMF signal detection device 310, a delay of “frequency” for one period = 20 ms can occur at the longest until the determination result is output after the DTMF signal is input. That is, the number of seconds of the delay is set from the beginning within a range that does not particularly affect the operation of the telephone exchange, the IVR system, or the like after receiving the determination result.

  The present invention has been described with reference to the specific embodiments shown in the drawings. However, the present invention is not limited to the embodiments shown in the drawings, and any known hitherto provided that the effects of the present invention are achieved. Even if it is a structure, it is employable.

  Regarding the embodiment described above, the main points of the new technical contents are summarized as follows. In addition, although part or all of the said embodiment is summarized as follows as a novel technique, this invention is not necessarily limited to this.

(Supplementary note 1) DTMF signal detection device for detecting the presence or absence of a DTMF (Dual-Tone Multi-Frequency) signal composed of two different frequency components from the input audio signal and outputting the type of the detected DTMF signal Because
Frequency analysis means for analyzing the intensity of each use frequency predetermined as a standard of the DTMF signal in the audio signal;
DTMF signal determination means for determining the presence / absence of the DTMF signal included in the audio signal and the type of the DTMF signal from the analysis result of the frequency analysis means and outputting them;
A DTMF signal detection apparatus comprising: frequency analysis control means for instructing suppression of operation of the frequency analysis means in accordance with a determination result of the DTMF signal determination means.

(Supplementary Note 2) The frequency analysis means includes:
A frequency intensity analysis unit for detecting a signal intensity for each use frequency predetermined as a standard of the DTMF signal;
A control communication unit for instructing each of the frequency intensity analysis means to specify a start time and an end time of the signal intensity detection process in accordance with the frequency and length of frequency intensity analysis instructed by the frequency analysis control unit. The DTMF signal detection apparatus according to appendix 1.

(Supplementary Note 3) The frequency analysis control means includes:
A determination result receiving unit that receives detection information indicating whether or not the DTMF signal output from the DTMF signal determination unit is being detected;
A determination result storage unit that stores the received detection information as a detection state table in a storage unit provided in advance;
A frequency analysis accuracy determination unit that determines the detection accuracy of the DTMF signal required according to the contents of the detection state table;
The DTMF signal detection apparatus according to appendix 2, further comprising: an instruction transmission unit that transmits the determined detection accuracy to the frequency analysis unit.

(Additional remark 4) When the said DTMF signal determination means detects the said DTMF signal now, the said frequency analysis control means instruct | indicates suppression of the detection accuracy of the said DTMF signal to the said frequency analysis means immediately after that The DTMF signal detection apparatus according to appendix 1.

(Supplementary Note 5) The frequency analysis control means is such that the DTMF signal determination means is not currently detecting the DTMF signal, and the elapsed time from the detection end time immediately before the DTMF signal is less than a predetermined value. The DTMF signal detection apparatus according to appendix 4, wherein in some cases, the frequency analysis means is instructed to suppress detection accuracy of the DTMF signal.

(Supplementary Note 6) When the frequency analysis control unit receives option reproduction information indicating that the state is before sending voice guidance including information on options that can be input by the user from a separately provided voice guidance transmission device The DTMF signal detection apparatus according to appendix 1, wherein the frequency analysis means is instructed to suppress detection accuracy of the DTMF signal.

(Supplementary Note 7) The frequency analysis means includes a DTMF signal storage unit that stores the DTMF signal input in the past,
The frequency analysis control means instructs the frequency analysis means to operate intermittently while suppressing the detection accuracy of the DTMF signal,
When the DTMF signal determining means detects that the DTMF signal has changed between the previous operation and the current operation of the frequency analyzing means, the change in the DTMF signal is made to the frequency analyzing means. The DTMF signal detection apparatus according to appendix 1, wherein the DTMF signal input in the detected time zone is instructed to be analyzed without suppressing detection accuracy.

(Supplementary Note 8) To a DTMF signal detection device that detects the presence or absence of a DTMF (Dual-Tone Multi-Frequency) signal composed of two different frequency components from an input audio signal and outputs the type of the detected DTMF signal There,
The frequency analysis means analyzes the intensity of each use frequency predetermined as the standard of the DTMF signal in the audio signal,
From the analysis result of the frequency analysis means, the DTMF signal determination means determines the presence or absence of the DTMF signal included in the audio signal and the type of the DTMF signal, and outputs these,
A method for detecting a DTMF signal, wherein the frequency analysis control means instructs the suppression of the operation of the frequency analysis means in accordance with a determination result of the DTMF signal determination means.

(Additional remark 9) In the DTMF signal detection apparatus which outputs the kind of the said DTMF signal detected by detecting the presence or absence of DTMF (Dual-Tone Multi-Frequency) signal from the input audio | voice signal,
In the computer provided in the DTMF signal detection device,
A procedure for analyzing the intensity of each use frequency predetermined as a standard of the DTMF signal in the audio signal;
A procedure for determining the presence or absence of the DTMF signal included in the audio signal and the type of the DTMF signal from the analysis result of the frequency analysis means and outputting them;
And a DTMF signal detection program for executing a procedure for instructing suppression of the detection operation in accordance with a determination result of the DTMF signal determination means.

  The present invention is applicable to a telephone exchange that detects a DTMF signal transmitted from a telephone and relays a call to a telephone number indicated by the DTMF signal, or an IVR system that operates in response to the DTMF signal. is there.

10, 150, 210, 310 DTMF signal detector 11, 11a, 11b, 11c, 11n Audio signal receiving means 12, 12a, 12b, 12c, 12n, 312, 312a, 312b, 312c, 312n Frequency analyzing means 13, 13a, 13b, 13c, 13n, 313, 313a, 313b, 313c, 313n DTMF signal determination means 14, 154, 214, 314 Frequency analysis control means 21 Sampling data receiving section 22, 22a, 22b, 22m, 322, 322a, 322b, 322m Frequency intensity analysis unit 23 Analysis result transmission unit 24 Control communication unit 31 Determination result reception unit 32 Determination result storage unit 33, 163, 233, 333 Frequency analysis accuracy determination unit 34 Instruction transmission unit 35 DTMF signal detection state table 35a Session ID
35b Status 35c Detection start time 35d Detection end time 110, 510 Server device 111 Network interface 112 CPU
DESCRIPTION OF SYMBOLS 113 External storage device 114 Voice interface 121a, 121b IP telephone 122 IP network 131a, 131b Analog telephone 132 Conversion apparatus 133 Analog telephone network 201 Voice automatic response apparatus 220 Voice guidance transmission apparatus 230 Processing apparatus 236 Guidance information receiving part 240 Communication apparatus 325 DTMF Signal storage unit

Claims (8)

A DTMF signal detection apparatus that detects the presence or absence of a DTMF (Dual-Tone Multi-Frequency) signal composed of two different frequency components from an input audio signal and outputs the type of the detected DTMF signal,
Frequency analysis means for analyzing the intensity of each use frequency predetermined as a standard of the DTMF signal in the audio signal;
DTMF signal determination means for determining whether or not the DTMF signal included in the audio signal is being detected from the analysis result of the frequency analysis means and the type of the DTMF signal and outputting them;
Frequency analysis control means for instructing suppression of the operation of the frequency analysis means according to the determination result of the DTMF signal determination means,
The frequency analysis control means is
A determination result receiving unit that receives detection information indicating whether or not the DTMF signal output from the DTMF signal determination unit is being detected;
A determination result storage unit that stores the received detection information as a detection state table in a storage unit provided in advance;
A frequency analysis accuracy determination unit that determines the detection accuracy of the DTMF signal required according to the contents of the detection state table;
An DTMF signal detection apparatus comprising: an instruction transmission unit configured to transmit the determined detection accuracy to the frequency analysis unit. The frequency analysis means comprises:
A frequency intensity analysis unit for detecting a signal intensity for each use frequency predetermined as a standard of the DTMF signal;
A control communication unit for instructing each of the frequency intensity analysis units to start and end the signal intensity according to the frequency and length of frequency intensity analysis instructed by the frequency analysis control unit; The DTMF signal detection device according to claim 1.   The frequency analysis control means instructs the frequency analysis means to suppress the detection accuracy of the DTMF signal immediately after the DTMF signal determination means detects the DTMF signal at present. Item 4. The DTMF signal detection device according to Item 1.   When the frequency analysis control unit is not currently detecting the DTMF signal and the elapsed time from the detection end time immediately before the DTMF signal is equal to or less than a predetermined value, 4. The DTMF signal detection apparatus according to claim 3, wherein the frequency analysis means is instructed to suppress detection accuracy of a DTMF signal.   When the frequency analysis control means receives the option reproduction information indicating that it is in a state before transmitting voice guidance including information on options that can be input by the user from a separately provided voice guidance transmission device, the DTMF signal 2. The DTMF signal detection apparatus according to claim 1, wherein suppression of detection accuracy is instructed to the frequency analysis means. The frequency analysis means includes a DTMF signal storage unit that stores the DTMF signal input in the past,
The frequency analysis control means instructs the frequency analysis means to operate intermittently while suppressing the detection accuracy of the DTMF signal,
When the DTMF signal determining means detects that the DTMF signal has changed between the previous operation and the current operation of the frequency analyzing means, the change in the DTMF signal is made to the frequency analyzing means. The DTMF signal detection apparatus according to claim 1, wherein the DTMF signal input in the detected time zone is instructed to be analyzed without suppressing detection accuracy. In a DTMF signal detection device for detecting the presence or absence of a DTMF (Dual-Tone Multi-Frequency) signal composed of two different frequency components from an input audio signal and outputting the type of the detected DTMF signal,
The frequency analysis means analyzes the intensity of each use frequency predetermined as the standard of the DTMF signal in the audio signal,
From the analysis result of the frequency analysis means, the DTMF signal determination means determines whether the DTMF signal included in the audio signal is being detected and the type of the DTMF signal, and outputs these.
The determination result receiving unit of the frequency analysis control unit receives detection information indicating whether or not the DTMF signal output from the DTMF signal determination unit is being detected,
The received detection information is stored as a detection state table in a storage unit provided in advance with a determination result storage unit of the frequency analysis control unit,
The frequency analysis accuracy determination unit of the frequency analysis control means determines the detection accuracy of the DTMF signal required according to the contents of the detection state table,
A method of detecting a DTMF signal, wherein the instruction transmission unit of the frequency analysis control unit transmits the determined detection accuracy to the frequency analysis unit to instruct suppression of operation of the frequency analysis unit. In a DTMF signal detection device that detects the presence or absence of a DTMF (Dual-Tone Multi-Frequency) signal from an input audio signal and outputs the type of the detected DTMF signal,
In the computer provided in the DTMF signal detection device,
A procedure for analyzing the intensity of each use frequency predetermined as a standard of the DTMF signal in the audio signal;
A procedure for determining whether or not the DTMF signal included in the audio signal is being detected from the analysis result of the intensity of each used frequency and the type of the DTMF signal and outputting them;
A procedure for receiving detection information indicating whether the output DTMF signal is being detected;
A procedure for storing the received detection information in a storage means provided in advance as a detection state table;
A procedure for determining the required detection accuracy of the DTMF signal according to the contents of the detection state table;
And a program for instructing suppression of detection operation in accordance with the determined detection accuracy.

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