JP2002094589A - Detector for dtmf signal and method for detecting dtmf signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the used data memory quantity of a BPF(Band-Pass Filter) when realizing operations with a DSP(Digital Signal Processor). SOLUTION: 1st/2nd BPFs 1/2 make the frequency signals of predetermined areas included in digital signals inputted according to 1st/2nd pieces of coefficient data 4/5 pass, respectively, and a controlling part 3 sends the 1st/2nd pieces of coefficient data 4/5 for making the signals of the entire area of high group/low group among DTMF(Dual Tone Multifrequency) signals pass to the 1st/2nd BPFs 1/2, respectively. When outputs equal to or more than a predetermined level exist in the BPFs 1/2, respectively, which DTMF signals in the entire area of the high group/low group are made to pass through are detected respectively by making the BPFs 1/2 change the data 4/5, sending the data 4/5 respectively and checking the outputs of the BPFs 1/2. The DSP realizes these operations that output dial data shown by a pair of the detected DTMF signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual tone multi-frequency (hereinafter referred to as "DTMF") signal detecting apparatus and a DTMF signal detecting method.
The present invention relates to a DTMF signal detection device and a DTMF signal detection method that use a plurality of bandpass filters (hereinafter, referred to as BPFs) and transmit dial data based on the frequency of a signal passing through these BPFs.

[0002]

2. Description of the Related Art A conventional DTMF signal detecting apparatus and DT
An MF signal detection method will be described with reference to FIG. 7 which shows a block diagram of a conventional DTMF signal detection device.

[0003] In the ordinary telephone system, the PCM system is general, so that the digital signal (including the DTMF signal) in FIG. 7 is quantized data of 8 kHz sampling.
This digital signal is applied to each DTMF signal frequency (high group frequency signal frequency: 1633 Hz, 1477 Hz, 133
6 Hz and 1209 Hz, frequency of low group frequency signal: 9
The signals are input in parallel to eight digital filters 11a to 11h (hereinafter, referred to as BPFs) that pass 41 Hz, 852 Hz, 770 Hz, and 697 Hz.
The signals that have passed through the BPFs 11a to 11h are input in parallel to the correction processing units 12a to 12h for each DTMF signal, and correct the high or low frequency level attenuated for each frequency of the DTMF signal. The high group frequency signal that has passed through the correction processing units 12a to 12d is input to the high group level determination unit 3, and the low group frequency signal that has passed through the correction processing units 12e to 12h is input to the low group level determination unit. The determination unit and the low group level determination unit detect the highest frequency, respectively, and the results are input to the subsequent signal determination unit. The signal determination unit determines the continuous reception time of the received DTMF signal and the disconnection of the received signal indicated by the communication standard, determines the corresponding dial number from the frequency of the received DTMF signal, and determines the next external I / F unit. Output to The external I / F unit adjusts the read timing so that the external device or the microcomputer can read the output from the signal determination unit as dial data, and outputs the result as a determination result signal. As described above, in the conventional DTMF signal detection device, the BPF 11 for every eight DTMF signals is used for one digital signal.
a to 11h and the correction processing units 12a to 12h are operated in parallel, and the signal having the maximum level in each of the high and low groups is determined by the signal determination unit via the level determination unit.

When this is realized using a digital signal processor (hereinafter referred to as DSP), for example, a BPF is shown in FIG. 4 (FIG. 4 showing X [n] = input (N-th input data when sampled at a certain time), Y [n] = output (n-th output data when input-sampled at a certain time), Z-1 = data immediately before (Meaning the delay data), Hxx = coefficient (meaning the coefficient data and multiplying this value by the corresponding delay data), and + sign = sum, respectively. For example, the former stage is a low-pass filter and the latter stage is a high-pass filter. ), Each BP
The coefficient data for F, delay data, and filter output data (this data is composed of, for example, 32 Y [n] in order to detect whether or not there is an output) is a DSP.
Program memory and data memory are unnecessarily wasted. That is, for example, when a BPF having an order of 20 is considered, since there are eight BPFs, the number of coefficient data = 8 ×
20, the number of delay data = 8 × (20−1), the size of the filter output data = 8 × 32, and when each of them is stored in the memory of the same size, the required memory number of the coefficient data is 160 and the delay data 152 required memory
And the required number of memories for filter output data is 256, and the program memory is one of the number of memories for the coefficient data.
60 data memories, the number of memories for delay data is 15
A total of 408, which is a sum of two and 256 memories for filter output data, is required.

[0005] In recent years, DSPs have been used in portable telephones, and low-cost, high-performance DSPs have become available due to mass production effects.
The limitations still remain as problems, and there is a need to develop programs that make efficient use of the internal memory. Other functions, such as an echo canceller and an AGC, used for a key telephone apparatus, have a tendency to be multichannel compatible and integrated in a DSP, and it is increasingly necessary to use the internal memory of the DSP efficiently.

[0006]

The conventional DTM described above.
The F signal detecting apparatus and the DTMF signal detecting method are designed to convert a digital signal into eight B signals that pass each DTMF signal frequency.
The signal input in parallel to the PF and passed through the BPF is corrected in a high- or low-frequency level that is input in parallel to a correction processing unit for each DTMF signal and attenuated for each frequency of the DTMF signal. The high-group frequency signal that has passed through the processing unit is input to the high-group level determination unit, and the low-group frequency signal is input to the low-group level determination unit, and the high-group level determination unit and the low-group level determination unit each have the highest level. Detect the frequency,
The result is input to a subsequent signal determination unit, and the signal determination unit determines the continuous reception time of the received DTMF signal specified by the communication standard and determines whether the received signal is disconnected.
The corresponding dial number is determined from the frequency of the signal. If this is realized using a DSP, eight BPFs reside in parallel, so that the coefficient data, delay data, and filter output data for each BPF consume more than necessary the program memory and data memory of the DSP. Problem.

[0007] The object of the present invention is to eliminate such a conventional drawback by using a BPF when implemented using a DSP.
DTMF signal detection apparatus and DTMF signal detection method, in which delay data and filter output data do not use a DSP data memory more than necessary.

[0008]

SUMMARY OF THE INVENTION A DTMF signal detection apparatus according to the present invention receives a digital signal, receives first coefficient data to be used in its own filter, and converts the input digital signal according to the first coefficient data. A first band-pass filter (hereinafter, referred to as BPF) for passing a signal of a frequency in a predetermined region included therein, and the digital signal is input, and second coefficient data used in the filter itself is received. A second BPF for passing a signal of a frequency in a predetermined region included in the input digital signal according to second coefficient data, and a dual-tone multi-frequency (hereinafter, referred to as DTMF) signal. The first coefficient data for passing the signal of the entire high group is sent to the first BPF, and the signal of the low group of the DTMF signal is sent to the first BPF. Are transmitted to the second BPF, respectively, to indicate that the signal of the frequency in the predetermined region has passed through the first BPF and the second BPF, respectively. The first signal for passing either the signal of the high frequency first region or the signal of the low frequency second region in the entire high group when there is an output equal to or higher than a predetermined level, respectively.
To the first BPF, and the second BPF for passing either the signal of the high frequency third region or the signal of the low frequency fourth region in the entire low group. Is sent to the second BPF, and the output of the first BPF is checked, and the output of the first BPF is higher than or equal to the predetermined level. Sending the first coefficient data to the first BPF to pass either the high frequency fifth region signal or the low frequency sixth region signal at The output of the BPF is checked and the signal in the third region or the signal in the seventh region of the high frequency in the third region or the fourth region in the entire low group having the output equal to or higher than the predetermined level or the signal of the low frequency is output. 8 for passing either of the signals in the region 8 Wherein the second coefficient data second BPF
, And checks the output of the first BPF and outputs the DTMF signal indicating the frequency corresponding to the fifth region or the sixth region having the output equal to or higher than the predetermined level and the output of the second BPF. A control unit for transmitting predetermined dial data indicated by a set of the DTMF signal indicating a frequency corresponding to the seventh region or the eighth region having an output higher than or equal to the predetermined level. It is provided with.

In the DTMF signal detecting device according to the present invention, the first
The first BPF receives the first coefficient data, receives the first coefficient data, and passes a signal having a predetermined frequency or less included in the input digital signal according to the first coefficient data. And a low-pass filter (hereinafter, referred to as an LPF), which receives the first coefficient data and determines the first coefficient data at a frequency equal to or lower than the first frequency included in a signal passed through the first LPF according to the first coefficient data. A first high-pass filter (hereinafter, referred to as HPF) that passes a signal having the second frequency or higher.
The second BPF receives the digital signal, receives the second coefficient data, and passes a signal having a predetermined third frequency or less included in the input digital signal according to the second coefficient data. Receiving the second coefficient data and the third coefficient included in the signal that has passed through the second LPF according to the second coefficient data.
And a second HPF that passes a signal having a frequency equal to or lower than the predetermined frequency and equal to or higher than a predetermined fourth frequency.

According to the DTMF signal detection method of the present invention, a digital signal including a DTMF signal is input by a first BPF having first coefficient data and a second BPF having second coefficient data, respectively, In accordance with the first coefficient data and the second coefficient data, a signal of a frequency in a predetermined region included in the input digital signal is passed, and the frequency of the signal passed through the first BPF and the second BPF In the DTMF signal detection method of transmitting predetermined dial data indicated by a set of the frequency of the passed signal, the first coefficient data for passing the signal of the entire high group of the DTMF signals is converted to the first coefficient data. 1 to the second BPF, and the second coefficient data for passing the signal of the entire low group of the DTMF signals to the second BPF. Wherein said first BPF second BP
A DTMF signal sense phase for detecting, by the first BPF and the second BPF, an output equal to or higher than a predetermined level indicating that F has passed a signal of a frequency in the predetermined region, respectively, After detecting the output equal to or higher than the predetermined level in the DTMF signal sense phase by the first BPF and the second BPF, respectively, the signal in the first region of the high frequency or the low frequency in the entire high group is detected. The first coefficient data for passing any one of the signals in the second area of the first BP
F, and passes the second coefficient data for passing either the signal of the high frequency third region or the signal of the low frequency fourth region within the entire low group to the second coefficient data.
To the BPF, and examines the output of the first BPF, detects that there is an output of the predetermined level or more in the first area or the second area in the entire high group, and A first detection frequency for checking the output of the second BPF and detecting that the output is equal to or higher than the predetermined level in the third area or the fourth area in the entire low group.
After detecting that there is an output of the predetermined level or more in the stage fetch phase and the detection frequency first stage fetch phase, it is detected that there is an output of the predetermined level or more in the entire high group. The first coefficient data for passing either the signal of the fifth region of the high frequency or the signal of the sixth region of the low frequency in the first region or the second region. The first BPF
And a signal of a high frequency seventh region in the third region or the fourth region where it is detected that the output is equal to or higher than the predetermined level in the entire low group. Or the second coefficient data for passing any one of the signals in the low-frequency eighth region is sent to the second BPF, and the output of the first BPF is checked to check the fifth region or the fifth region. In the area of No. 6, the output of the predetermined level or more is detected, and the output of the second BPF is checked. In the seventh area or the eighth area, the output of the predetermined level or more is detected. A detection frequency second-stage fetch phase for detecting that there is an output, and after detecting that there is an output of the predetermined level or more in the detection frequency second-stage fetch phase, the detection frequency second-stage fetch phase 1 BP And a DTMF signal indicating a frequency corresponding to the fifth region or the sixth region, which has detected that the output is equal to or higher than the predetermined level. 2 B
Predetermined dial data indicated by a set of the DTMF signal indicating the frequency corresponding to the seventh region or the eighth region, which is obtained by checking the output of the PF and detecting that the output is equal to or higher than the predetermined level. DTMF to send
And a signal detection confirmation phase.

[0011] In the DTMF signal detection method of the present invention, the reception DTMF signal detection decision phase includes the detection frequency second.
The fifth region or the sixth region in which the output of the first BPF is checked in the stage fetch phase and the presence of the output equal to or higher than the predetermined level is detected, and the detected frequency is in the second stage fetch phase. Checking the output of the second BPF and detecting that there is an output equal to or higher than the predetermined level continuously for a predetermined time with the seventh area or the eighth area and equal to or higher than the predetermined level; Of the frequency corresponding to the fifth region or the sixth region when it is detected that there is an output of the predetermined level or more continuously for the predetermined time. The predetermined dial data represented by a set of the DTMF signal shown and the DTMF signal showing the frequency corresponding to the seventh area or the eighth area is transmitted.

[0012]

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

FIG. 1 is a block diagram showing an embodiment of a DTMF signal detecting device according to the present invention.

In this embodiment shown in FIG. 1, a digital signal is input, first coefficient data 4 used in its own filter is received, and a predetermined value included in the input digital signal is determined according to the first coefficient data 4. A first bandpass filter (hereinafter, referred to as BPF) that passes a signal having a frequency in the region where the signal has passed, a second signal that receives a digital signal and receives second coefficient data 5 used in the filter itself. A second BPF 2 that passes a signal of a frequency in a predetermined region included in the input digital signal according to data 5
And first coefficient data 4 for passing a signal of the entire high group (all high group frequency signals) of the DTMF signal.
To the first BPF 1, and second coefficient data 5 for passing the signal of the entire low group (all the low group frequency signals) of the DTMF signal to the second BPF 2, respectively. Each of the BPF1 and the second BPF2 has an output that is equal to or higher than a predetermined level indicating that signals of frequencies in predetermined regions (in this case, the entire region of the high group and the entire region of the low group) have passed. The signal of the first region of high frequency or the second signal of low frequency
The first coefficient data 4 for passing any one of the signals in the region of the low group is sent to the first BPF 1 and the signal of the high frequency third region or the low frequency fourth region within the entire low group. Is transmitted to the second BPF2, the output of the first BPF1 is checked, and the first area in the entire high group having an output equal to or higher than a predetermined level is output. The first coefficient data 4 for passing either the signal of the fifth region of the high frequency or the signal of the sixth region of the low frequency within the first or second region.
F1 and the output of the second BPF2, and the signal of the high frequency seventh region in the third region or the fourth region within the entire low group having an output of a predetermined level or more. Or sending the second coefficient data 5 to the second BPF 2 for passing either the signal of the eighth region of the low frequency to the second BPF 2,
The output of the first BPF1 is checked, and the DTMF signal indicating the frequency corresponding to the fifth region or the sixth region having the output of the predetermined level or more and the output of the second BPF2 are checked and the output of the second BPF2 is higher than the predetermined level. And a control unit 3 for transmitting predetermined dial data indicated by a set of a DTMF signal indicating a frequency corresponding to a certain seventh region or eighth region.

The first BPF 1 receives a digital signal, receives first coefficient data 4 from the control unit 3, and determines a predetermined first frequency included in the input digital signal according to the first coefficient data 4. A first low-pass filter that passes the following signals (hereinafter referred to as LPF)
And receives the first coefficient data 4 from the control unit 3 and, according to the first coefficient data 4, generates a signal having a frequency not higher than a first frequency and not lower than a predetermined second frequency included in a signal passed through the first LPF. The first high-pass filter (hereinafter referred to as H
Described as PF. The second BPF 2 receives a digital signal, receives the second coefficient data 5 from the control unit 3, and according to the second coefficient data 5, a predetermined second BPF 2 included in the input digital signal. A second LPF that passes a signal having a frequency equal to or lower than 3 and a second coefficient data 5 from the control unit 3 and a second LPF according to the second coefficient data 5.
And a second HPF that passes a signal having a frequency equal to or lower than a third frequency and equal to or higher than a predetermined fourth frequency included in the signal passed through the LPF.

[0016] Of the DTMF signals, the signals in the entire high group (all high group frequency signals) are 1209 Hz and 1336H.
z, 1477 Hz and 1633 Hz, which are signals in the entire low group of DTMF signals (all low group frequency signals)
Are 697Hz, 770Hz, 852Hz and 941H
z.

FIG. 1 also shows an external I / F section that adjusts the read timing and outputs the result as a determination result signal so that the external device or the microcomputer can read the output from the control section 3 as dial data. .

Next, the operation of the DTMF signal detecting device according to the present embodiment will be described in detail with reference to FIGS.

FIG. 2 is a diagram showing an example of the operation of the embodiment of the present invention and an example of the DTMF signal detecting method of the present invention.

FIG. 3 is a diagram showing BPFs corresponding to the respective DTMF signals L1 to L4 and U1 to U4.
1 to 28 (LPFs 101 to 10 of the configuration filter in FIG. 5)
8) and HPFs 31 to 38 (H of the constituent filter in FIG. 5)
PF 101 to 108) as shown in the drawing to create BPFs corresponding to the respective DTMF signals L1 to L4 and U1 to U4. However, the passing level on the vertical axis has no meaning.

FIG. 4 is a diagram showing an example of a BPF used in the present invention, where X [n] = input (n-th input data when sampled at a certain time), and Y [n] = output. (N-th output data at the time of input sampling at a certain time), Z-1 = previous data (meaning delay data), Hxx = coefficient (meaning coefficient data, and this value represents the corresponding delay Multiplication with data) and + sign = sum, for example, the former stage is a low-pass filter (LP
F), the subsequent stage is a high-pass filter (HPF). When the BPF is realized by the DSP, the number of delay data to be saved inevitably increases as the order of the filter increases, and the data memory capacity of the DSP increases accordingly. Similarly, the number of coefficient data of the filter necessarily increases as the order of the filter increases, and accordingly, the program memory capacity of the DSP also increases.

FIG. 5 is a diagram showing an example of the specifications of the BPF used in the present invention. The first coefficient data 4 and the second coefficient data 5 are given to the BPF coefficient data shown in FIG. Indicates that the BPF of items 101 to 114 is realized.

FIG. 6 is a diagram showing a list of dial data.

Referring to FIG. 1 and referring to FIG. 2, the first BPF 1 and the second BPF 2 each receive a digital signal including a DTMF signal, and the The first coefficient data 4 for passing the signal of the whole group is transmitted to the first BPF 1 (the first BPF 1 becomes the BPF of item 109 in FIG. 5 by this coefficient data), and the DTMF signal The second coefficient data 5 for passing the signal of the entire low group is sent to the second BPF 2 (the second BPF 2 is used to transmit the second coefficient data 5).
PF2 is the BPF of item 110 in FIG. ), The first B
The first BPF1 and the second BPF2 output at or above a predetermined level indicating that the PF1 and the second BPF2 have passed signals of frequencies in the entire high group region and the low group entire region, respectively.
PF2 respectively (that is, the DTMF signal is detected in both the entire region of the high group and the entire region of the low group of the DTMF signal from the digital signal. Here, the detection of the output of a predetermined level or more is shown in FIG. 4). Y [n] is 32, for example.
The mean value of the squares is calculated, and the average value is, for example, -8 dBm (60
It is assumed that the detection can be made at the time of (0 ohm meter) or more. The “detection of an output above a predetermined level” used in another part of the description of the present invention is also based on the method described above. ) (S1: DTM
F signal sense phase).

Next, the control unit 3 converts the first coefficient data 4 for passing either the signal of the high frequency first region or the signal of the low frequency second region in the entire high group. The first BPF 1 is sent to the first BPF 1 (based on the coefficient data, the first BPF 1
become. ), And the second coefficient data 5 for passing either the signal of the third region of the high frequency or the signal of the fourth region of the low frequency in the entire low group is converted to the second BPF.
2 (the second BPF 2 becomes the 113 or 114 BPF in FIG. 5 by this coefficient data) and the first BPF 2.
Of the BPF1 in the first group or the second area in the entire high group is detected, and the output of the second BPF2 is checked in the entire area of the low group. Within the third area or the fourth area within the high group (that is, the DTMF signal detected in the entire high group (high group DTMF signal) is detected in the entire high group). Which of the high-frequency first area and the low-frequency second area is detected, and whether the DTMF signal (low-group DTMF signal) detected in the entire low-group is higher than the high-frequency It is determined which of the third region and the fourth region having the lower frequency has been detected) (S2:
Detection frequency first stage fetch phase).

Next, the control unit 3 detects a high-frequency fifth region in the first region or the second region in which it is detected that the output is equal to or higher than a predetermined level in the entire high group. To the first BPF 1 (in this case, it is detected that there is an output higher than a predetermined level). When it is within the first area, the first BPF 1 becomes the BPF of item 108 or 107 in FIG. 5 based on the coefficient data, and it is detected that the output is equal to or higher than the predetermined level. Is within the second area, the first BPF 1 is determined by this coefficient data as shown in FIG.
The BPF of item 106 or 105 is obtained. ),Also,
A signal of a high-frequency seventh region or a low-frequency eighth region in the third region or the fourth region where it is detected that the output is equal to or higher than the predetermined level in the entire low group. The second coefficient data 5 for passing any one of the signals is sent to the second BPF 2 (at this time, when it is detected in the third area that the output is equal to or higher than the predetermined level, According to the coefficient data, the second BPF 2 becomes the BPF of the item 104 or 103 in FIG. 5, and it is detected that the second BPF 2 has an output of a predetermined level or more.
When the coefficient is within the area of
BPF2 becomes the BPF of item 102 or 101 in FIG. ), Checking the output of the first BPF1 to detect that there is an output of a predetermined level or more in the fifth area or the sixth area, and checking the output of the second BPF2 in the seventh area or the eighth area. (Ie, a high frequency region and a low frequency region in the first region or the second region determined by the detection frequency first stage fetch phase (S2)). In which of the three areas the high-group DTMF signal was detected, and in which of the high-frequency area and the low-frequency area in the third or fourth area the low-group DTMF signal was detected. It is determined whether or not it has been detected) (S3: second stage fetch phase of detection frequency).

Next, the control unit 3 detects a fifth area or a sixth area in which it is detected that the output is higher than a predetermined level in the second-stage fetch phase (S3).
It is detected that there is an output of a predetermined level or more continuously for a predetermined time (for example, 30 msec or more) with the seventh area or the eighth area, and a predetermined level or more is continuously output for a predetermined time. When it is detected that there is an output of D, the frequency D corresponding to the fifth area or the sixth area indicates D
Transmission of predetermined dial data indicated by a set of a TMF signal and a DTMF signal indicating a frequency corresponding to the seventh region or the eighth region (that is, a high frequency determined by the second stage fetch phase (S3) of the detection frequency). The high group DTMF signal and the low group DT are continuously arranged for a predetermined time in an area where the group DTMF signal is detected and an area where the low group DTMF signal is detected.
An MF signal is detected, and when a high group DTMF signal and a low group DTMF signal can be detected continuously for a predetermined time, it is determined that the high group DTMF signal and the low group DTMF signal have been correctly received. Then, the predetermined dial data shown in FIG. 6 is transmitted by the combination of the high group DTMF signal and the low group DTMF signal) (S4: reception DTMF signal detection decision phase).

The control unit 3 controls the second detection frequency.
High group DTM determined by stage fetch phase (S3)
A high group DTMF signal and a low group DTMF signal are detected in an area where the F signal is detected and an area where the low group DTMF signal is detected, and the high group DTMF signal and the low group D are continuously detected for a predetermined time.
When it is no longer possible to detect the TMF signal, it is determined that the transmission of the DTMF signal from the transmission source is completed (S5: DT
MF signal disconnection detection phase).

If the above operations from S1 to S5 are realized using a DSP, for example, considering a BPF of order 20, in the present invention, two BPFs of a first BPF1 and a second BPF2 are used. Therefore, the number of delayed data = 2 × (20−
1) number, filter output data size = 2 × 32, coefficient data are DTMF signals L1 to L4 and U1 to U
4 are required, and the number of coefficient data becomes 8 × 20,
When each of them is stored in a memory of the same size, the required number of memories for coefficient data is 160, the required number of memories for delayed data is 38, and the required number of memories for filter output data is 6
4, the program memory requires 160, the number of memories for the coefficient data, and the data memory, the sum of 38 for the delay data and 64 for the filter output data, requires 102, respectively. .

[0030]

As described above, the DTMF of the present invention is
According to the signal detection device and the DTMF signal detection method, a digital signal is input by the first BPF, and a signal of a frequency in a predetermined region included in the input digital signal is passed according to first coefficient data. , The second B
A digital signal is input by the PF, and a signal having a frequency in a predetermined region included in the input digital signal is passed according to the second coefficient data.
The first coefficient data for passing the signal of the entire high group of the DTMF signals is passed to the first BPF,
The second coefficient data for passing the signal of the entire low group among the MF signals is sent to the second BPF, and the first BPF and the second BPF each have an output higher than a predetermined level. The first coefficient data for passing either the signal of the high frequency first region or the signal of the low frequency second region in the entire high group
To the second BPF, and second coefficient data for passing either the signal of the high frequency third region or the signal of the low frequency fourth region within the entire low group is transmitted to the second BPF. Checking the output of the first BPF, the signal in the fifth region of the high frequency or the signal of the low frequency in the first region or the second region within the entire high group having an output of a predetermined level or more. 6 is sent to the first BPF to pass either of the signals in the area of No. 6 and the second BPF
And a signal in a high-frequency seventh region or a low-frequency eighth region signal in the third region or the fourth region within the entire low group having an output equal to or higher than a predetermined level. Is sent to the second BPF, and the output of the first BPF is checked to correspond to a fifth area or a sixth area having an output equal to or higher than a predetermined level. A predetermined dial indicated by a set of a DTMF signal indicating a frequency and an output of the second BPF and a DTMF signal indicating a frequency corresponding to a seventh region or an eighth region having an output equal to or higher than a predetermined level. This operation is implemented using a DSP to transmit data (for example, when the order is 2).
0), the first BPF and the second BP
Since only two BPFs with F are used, the number of delay data = 2 × (20−1) and the size of filter output data (for example, when 32 output data are used) = 2 ×
32 pieces of coefficient data are required for 8 pieces of each DTMF signal, and the number of coefficient data becomes 8 × 20. When each piece is stored in the same size memory, the required number of memory of coefficient data is 160 and the need of delay data 38 memories,
The required number of memories for the filter output data is 64, and the program memory is 160 times the number of memories for the coefficient data.
And the data memory is a sum 102 of 38 memories for delay data and 64 memories for filter output data.
And a memory required when a conventional DTMF signal detection device in which eight BPFs are resident in parallel using a DSP is used (when a BPF having an order of 20 is considered, there are eight BPFs). Therefore, the number of coefficient data = 8 × 2
0, the number of delayed data = 8 × (20−1), the size of the filter output data = 8 × 32, and when each of them is stored in a memory of the same size, the required number of memories of the coefficient data is 160, 152 required memory
And the required number of memories for filter output data is 256, and the program memory is one of the number of memories for the coefficient data.
60 data memories, the number of memories for delay data is 15
A total of 408, which is a sum of two and 256 memories for filter output data, is required. ), 306 data memories can be saved, and the data memory consumed by the DSP becomes smaller than in the conventional case.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a DTMF signal detection device according to the present invention.

FIG. 2 is a diagram illustrating an example of the operation of the exemplary embodiment of the present invention, and illustrating an example of the DTMF signal detection method of the present invention.

FIG. 3 is a diagram showing a BPF corresponding to each DTMF signal.

FIG. 4 is a diagram showing an example of a BPF used in the present invention.

FIG. 5 is a diagram showing an example of specifications of a BPF used in the present invention.

FIG. 6 is a diagram showing a dial data list.

FIG. 7 is a block diagram showing a conventional DTMF signal detection device.

[Description of Signs] 1 First BPF 2 Second BPF 3 Control unit 4 First coefficient data 5 Second coefficient data 11 BPF 12 Correction processing unit

Claims (6)

[Claims] 1. A digital signal is input, first coefficient data used in a filter is received, and a signal of a frequency in a predetermined region included in the input digital signal is passed according to the first coefficient data. A first band-pass filter (hereinafter referred to as a BPF), and a second band-pass filter which receives the digital signal and uses the digital signal in its own filter.
A second BPF that receives a coefficient data of a predetermined frequency included in the input digital signal according to the second coefficient data, and a dual tone multi-frequency (hereinafter referred to as DTM).
Described as F. ) The first coefficient data for passing the signal of the entire high group out of the signals into the first BPF
In addition, the second coefficient data for passing the signal of the entire low group of the DTMF signal is transmitted to the second BPF.
Respectively, the first BPF and the second BPF
When there is an output of a predetermined level or more indicating that the signal of the frequency of the predetermined region has passed, respectively, the signal of the high frequency first region or the low frequency within the entire high group. Sends the first coefficient data to the first BPF for passing any of the signals in the second region of the second group, and also outputs the signal of the third region of the high frequency or the low frequency in the entire low group. Sending the second coefficient data for passing any of the signals in the fourth region to the second BPF, examining the output of the first BPF, and having an output equal to or higher than the predetermined level. The first for passing either the high frequency signal in the fifth region or the low frequency signal in the sixth region within the first region or the second region within the entire high group; Of the first BPF And checking the output of the second BPF, and checking the output of the second BPF. The seventh high frequency signal in the third region or the fourth region in the entire low group having an output higher than the predetermined level. Sending said second coefficient data to said second BPF to pass either a signal in the region or a signal in the eighth region at a lower frequency, said first BPF
And the DTMF signal indicating the frequency corresponding to the fifth region or the sixth region having an output equal to or higher than the predetermined level and the output of the second BPF are checked. A control unit for transmitting predetermined dial data indicated by a set of the DTMF signal indicating a frequency corresponding to the seventh area or the eighth area having an output, and a DTMF signal. Signal detection device. 2. The first BPF receives the digital signal, receives the first coefficient data, and determines a predetermined first frequency included in the input digital signal according to the first coefficient data. The first to pass the following signals
A first low-pass filter (hereinafter, referred to as an LPF); receiving the first coefficient data and determining the first coefficient data at a frequency equal to or lower than the first frequency included in the signal passed through the first LPF according to the first coefficient data A first high-pass filter (hereinafter, referred to as an HPF) that passes a signal having a frequency equal to or higher than a second frequency, wherein the second BPF receives the digital signal and receives the second coefficient data. A second LPF that passes a signal having a frequency equal to or lower than a predetermined third frequency included in the input digital signal according to the second coefficient data, and a second coefficient that receives the second coefficient data. A second HPF that passes a signal having a frequency equal to or lower than the third frequency and equal to or higher than a predetermined fourth frequency included in a signal that has passed through the second LPF according to data. DTMF signal detection apparatus according to claim 1,. 3. The signal of the entire high group of the DTMF signals is 1209 Hz, 1336 Hz, 1477 Hz.
The DTMF signal detecting device according to claim 1 or 2, wherein the frequency is 1633 Hz. 4. A signal of the entire low group of the DTMF signals is 697 Hz, 770 Hz, 852 Hz, and 9%.
4. The DTMF signal detecting device according to claim 1, wherein the frequency is 41 Hz. 5. A first BPF having first coefficient data
And the second BPF having the second coefficient data, DT
A digital signal including an MF signal is input, and a signal of a frequency in a predetermined region included in the input digital signal is passed according to the first coefficient data and the second coefficient data. In a DTMF signal detection method for transmitting predetermined dial data indicated by a set of a frequency of a signal passed by a BPF and a frequency of a signal passed by a second BPF, a signal of the entire high group of the DTMF signals is The first coefficient data for passing the signal is sent to the first BPF, and the second coefficient data for passing the signal of the entire low group of the DTMF signal is sent to the second BPF.
And outputs an output of a predetermined level or higher indicating that the first BPF and the second BPF have passed signals of frequencies in the predetermined region, respectively, to the first BPF.
And DTMF detected by the second BPF, respectively.
A signal sense phase, and after detecting an output equal to or higher than the predetermined level in the DTMF signal sense phase by the first BPF and the second BPF, respectively, Sending the first coefficient data to the first BPF to pass either a low frequency signal or a low frequency second area signal; and a high frequency third signal within the low group. Sending said second coefficient data to said second BPF to pass either a region signal or a low frequency fourth region signal, said first BPF
Is detected in the first area or the second area in the entire high group, and the output of the predetermined level or more is detected, and the output of the second BPF is checked. A first-stage detection frequency fetch phase for detecting that there is an output equal to or higher than the predetermined level in the third area or the fourth area in the entire low group; After detecting that there is an output equal to or higher than the predetermined level in a phase, the first area or the second area where it is detected that there is an output equal to or higher than the predetermined level in the entire high group. The signal of the fifth region of the high frequency or the sixth signal of the low frequency in the region
The first coefficient data for passing any one of the signals in the region is sent to the first BPF, and it is detected that the output is equal to or higher than the predetermined level in the entire low group. The second coefficient data for passing either the signal of the seventh region of the high frequency or the signal of the eighth region of the low frequency in the third region or the fourth region is used as the second coefficient data. Sending to the second BPF, the first BPF
The output of the second BPF is detected in the fifth area or the sixth area, and the output of the second BPF is detected in the fifth area or the sixth area. A detection frequency second-stage fetch phase for detecting that there is an output of the predetermined level or more in the region, and after detecting that there is an output of the predetermined level or more in the detection frequency second-stage fetch phase. In the second stage fetch phase of the detection frequency, the output of the first BPF is examined, and the frequency corresponding to the fifth region or the sixth region detected as having the output equal to or higher than the predetermined level is detected. The DTMF signal shown in FIG. 7 and the output of the second BPF in the second stage fetch phase of the detection frequency are checked to detect the presence of an output equal to or higher than the predetermined level. A received DTMF signal detection decision phase for transmitting predetermined dial data indicated by a set of the DTMF signal indicated by a frequency corresponding to the eighth region. 6. The reception DTMF signal detection confirming phase is performed in the second stage fetch phase of the detection frequency.
The fifth region or the sixth region in which the output of the BPF is examined to detect that the output is equal to or higher than the predetermined level, and the output of the second BPF in the second stage fetch phase of the detection frequency. And that the output is equal to or higher than the predetermined level continuously for a predetermined time in the seventh area or the eighth area in which it is detected that the output is equal to or higher than the predetermined level. When it is detected that the output is equal to or higher than the predetermined level continuously for the predetermined time, the DTMF signal indicating the frequency corresponding to the fifth region or the sixth region and the DTMF signal indicating the seventh region are output. Or the DTM indicating a frequency corresponding to the eighth region or the eighth region.
6. The DT according to claim 5, wherein predetermined dial data indicated by a set with the F signal is transmitted.
MF signal detection method.