JP2000196773A - Communication terminal equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively detect the level of a tone signal of the frequency apart from the band of a carrier signal frequency through the use of the function of a MODEM by providing a signal level judgment mean for judging whether or not the signal level of a signal to be detected is not less than a prescribed threshold level. SOLUTION: A signal passing through a band-pass filter 21 is inputted to a power integrator 23 and the signal power is calculated. Output Sp from the power integrator 23 is inputted to a comparator 24. It is compared with a threshold which is stored in a threshold storage part 25 and is set by a system control part. The judged result is outputted as a signal level judgment result signal. The band-pass filter 21, the power integrator 23 and the power compactor 24 can easily be realized as the functions of the MODE which communication terminal equipment original has for converting and demodulating a communication signal. Thus, the level of the tone signal of the frequency apart from the band of a carrier signal frequency can inexpensively be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication terminal device such as a facsimile device including a tone detecting device.

[0002]

2. Description of the Related Art In a communication terminal apparatus such as a facsimile apparatus, it is sometimes necessary to disconnect a line by detecting a busy tone signal coming from the line during communication.

[0003] Specifically, in a facsimile machine,
If the other party is communicating or talking at the time of automatic call, and there is a busy tone signal of "PupPupPup" from the local exchange that contains the facsimile machine, the busy tone signal is detected. do it,
An example is a case in which a line is released to improve line use efficiency.

In a facsimile apparatus with an answering machine function, a voice message received from a user on the other side, which is received via a line when answering, is recorded, and the user on the other side who has finished speaking the message receives the message from the user on the other side. By disconnecting the line by hooking the handset,
The busy tone signal transmitted from the local exchange that houses the facsimile apparatus is detected, the recording operation of the voice message is terminated, and the useless signal (busy tone signal) is not recorded. In some cases,

As described above, a communication terminal device that performs a predetermined operation as needed when a busy signal on a line is detected must be able to accurately detect a busy signal on the line.

[0006] Further, even when waiting for a response from the exchange by detecting a dial tone signal coming from the line when the telephone goes off-hook at the time of dialing, the dial tone signal must be accurately detected. Also, by detecting a ringing signal coming from the line after going off-hook at the time of calling and transmitting a selection signal by a dial pulse or DTMF signal, it is possible to accurately detect the ringing signal even when confirming the operation of the exchange. Must. Also, when the line must be disconnected by transmitting a selection signal by going off-hook at the time of calling and detecting a busy tone signal coming from the line because the other party specified by the selection signal is communicating. There is.

A tone signal such as a busy tone signal, a dial tone signal, and a ring tone signal transmitted to a communication terminal device via a line is transmitted from a local exchange in which the communication terminal device is accommodated. Therefore, if the characteristics of the tone signals transmitted by all the local exchanges in the line are the same in all the local exchanges, no matter what the local exchange in the line accommodates, Should be able to accurately detect the tone signal on the line.

In a telephone line in Japan, the tone signal transmitted from the local exchange is a signal of 400 ± 19 Hz.
The dial tone signal is based on the continuous transmission of the 400 Hz ± 19 Hz signal, and the ring tone signal is the 400 Hz ± 19 Hz signal.
A signal of ± 19 Hz is modulated at a modulation rate of 85 ± 15% within a range of 15 Hz or more and 20 Hz or less.
The 400 Hz ± 19 Hz signal is converted to a make rate of 50% ± 1.
Modulated at 0% and 60 cycles ± 20% per minute.

[0009] However, in some countries, the characteristics of the tone signal actually transmitted from the local exchange in the line are:
There may be cases where the characteristics do not match the characteristics specified in the country, even if the tone signal detection characteristics of the tone detection device included as a configuration in the communication terminal device are set in accordance with the characteristics of the tone signals specified in the country. The characteristic of the tone signal transmitted from each local exchange in the line varies, and the detection characteristic of the tone signal in the communication terminal apparatus and the characteristic of the tone signal transmitted by the local exchange accommodating the communication terminal apparatus are different. In some cases, the characteristics do not match, and the tone signal on the line cannot be detected.

On the other hand, taking into account the variation in the characteristics of the tone signals transmitted to each of the local exchanges in the line, the tone signal detection characteristics of the tone detection device on the communication terminal device side can be widened. In this case, the communication signal on the line or the voice sound of the conversation is erroneously detected as a busy tone signal, and the line is disconnected during communication, or the line is suddenly disconnected while recording a voice message. Malfunction may occur.

In addition, not only in the case of being accommodated in a telephone line subscriber exchange, but also in the case of being accommodated in an extension line exchange, if the characteristics of tone signals transmitted by the exchanges in the extension line vary, A similar problem arises.

As described above, it is important to accurately detect a tone signal arriving from a line irrespective of the installation location of a device in order to perform normal communication.

On the other hand, with the spread of information communication such as facsimile communication in recent years, the cost of communication terminal devices such as facsimile devices has been desired to be further reduced, but communication terminal devices such as facsimile devices have not been used. Therefore, different operation specifications are required for each destination because of the necessity of conforming to the line standard of the country of operation.

[0014] Therefore, in order to satisfy the demand for lowering the price while suppressing the cost of the apparatus, hardware having different operation specifications for each destination is designed in common and different settings are made for each destination, so that each destination is set differently. The operation specifications required for each location are satisfied.

This is not an exception in a tone detection device applied to a communication terminal device, and parameters for detecting a detection target signal coming from a line as a tone signal, specifically, a threshold of a frequency range and a detection level. The value setting is changed by a program so that tone signals having different characteristics for each destination can be accurately detected.

In the tone detecting device, when it is determined whether or not a signal to be detected coming from a line is a tone signal, the signal to be detected may be a band-pass signal having an appropriate frequency range set as a tone signal. There is a configuration in which the power of a signal input to a filter and output from the band-pass filter is compared with a predetermined threshold level to determine whether or not the signal is a tone signal. The setting for each destination is performed by setting the characteristics of the band-pass filter and setting the predetermined threshold value.

The characteristics of the band-pass filter, specifically, the setting of the center frequency, the pass band width, the cutoff characteristics, etc. can be performed by changing the setting of the filter coefficient group. However, for example, even when two of the center frequency, the pass band width, and the cutoff characteristic are fixed and the remaining one is changed, it is necessary to change all the file coefficient values constituting the filter coefficient group. .

In order to realize the desired filter characteristics of the band-pass filter, it is necessary to precisely calculate and actually verify each filter coefficient value constituting the filter coefficient group.

Therefore, for each of a large number of filter characteristics that may be set for each destination, all the corresponding filter coefficient groups are calculated, actually verified, and all the filter coefficients are prepared in case that they are set. It is necessary to hold the coefficient group in a memory.

In addition to the setting change of the filter characteristics for each destination, a large number of filter characteristics are also supported so that a service person can fine-tune various characteristics of the tone detecting device at the actual installation location of each device. All filter coefficient groups need to be stored in the memory.

Another example of a circuit configuration for determining whether or not a signal to be detected coming from a line is a tone signal in a tone detecting device is another example of a circuit in which a signal to be detected is binary-coded by a hysteresis comparator or the like. There is a method in which a frequency detector that measures the frequency of a binarized signal with a frequency counter determines whether the detection target signal is within a predetermined frequency range.

[0022]

In this method, the frequency range to be detected as a tone signal can be easily changed. However, in order to change the threshold level to be detected as a tone signal for each destination, the frequency detection must be performed. It is necessary to precede a variable gain amplifier in the vessel, and the cost cannot be reduced.

Also, a modem device such as a facsimile modem includes an AGC circuit for demodulating a received signal, and it is possible to calculate the level of an input signal from the amplification indicated by the AGC. In operation, there is a case where a signal reacts only to a carrier signal band to be demodulated and does not react to an input signal having a different frequency band from a carrier signal such as a tone signal such as a dial tone.

The present invention has been made in view of the above circumstances, and it is possible to detect the level of a tone signal having a frequency distant from the carrier signal frequency band at low cost by using the function of a modem. It is another object of the present invention to provide a communication terminal device capable of flexibly changing the setting of tone signal detection characteristics.

[0025]

In order to achieve the above object, a communication terminal according to the present invention determines a frequency and a signal level of a detection target signal arriving from a line, and determines a predetermined frequency range and a threshold. In a communication terminal device performing a predetermined operation by determining the detection detection target signal as a tone signal on condition that it is equal to or higher than a level, a band-pass filter to which a detection target signal coming from the line is input,
Power integration means for integrating the signal power output from the band-pass filter, and power comparison means for comparing the power level output from the power integration means with a predetermined threshold level; Based on the comparison result of the power level by the power comparing means when the coefficient group is temporarily set to a coefficient passing through the entire frequency band, it is determined whether or not the signal level of the detection target signal is equal to or higher than the predetermined threshold level. It is characterized by comprising signal level determining means for determining.

According to a second aspect of the present invention, in the communication terminal device according to the first aspect, the detection target signal is converted into a binary signal by a binarizer, and the binary signal from the binarizer is converted into a binary signal. It comprises a frequency determination unit that measures the frequency of the value signal and determines whether the frequency is within a predetermined frequency range, and the frequency of the detection target signal is determined by the frequency determination unit to be within the predetermined frequency range, and The detection target signal is determined to be a tone signal on condition that a state in which the signal level of the detection target signal is determined to be equal to or higher than the predetermined threshold level by the signal level determination means has continued for a predetermined time. I do.

According to a third aspect of the present invention, in the communication terminal device according to the first aspect, the detection target signal is converted into a binary signal by a binarizer, and the binary signal from the binarizer is converted to a binary signal. A state in which the frequency of the value signal is measured and the frequency of the signal to be detected is determined to be within the predetermined frequency range by frequency determining means for determining whether or not the frequency is within a predetermined frequency range. The signal level of the detection target signal is determined to be a tone signal on condition that the signal level of the detection target signal has been determined to be equal to or higher than the predetermined threshold level by the signal level determination means at the time when a predetermined time has elapsed. I do.

[0028]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described in detail.

First, FIG. 1 shows a block configuration of a facsimile apparatus 1 as a communication terminal apparatus according to an embodiment of the present invention.

In FIG. 1, a facsimile apparatus 1 includes a system control unit 2, a ROM 3, a RAM 4, a scanner 5, a plotter 6, an image memory 7, an encoding / decoding unit 8, an operation display unit 9, a communication control unit 10, a network control unit. It comprises a unit 11 and a system bus 12.

The system control unit 2 controls each unit of the apparatus according to the control program written in the ROM 3 while using the RAM 4 as a work area.

As described above, the ROM 3 is a read-only memory in which a control program and a data table for the system control unit 2 to control each unit of the apparatus are stored.

The RAM 4 is a random access memory used as a work area of the system control unit 2 as described above. The RAM 4 is backed up by a backup circuit (not shown), and the stored contents are retained even when the power of the apparatus is turned off.

The scanner 5 has 3.85 lines / mm, 7.7
This is for obtaining image data by reading a document image at a predetermined reading line density such as book / mm and 15.4 book / mm. The plotter 6 is for recording and outputting the received image data according to its linear density, and for recording and outputting (copying operation) the image data read by the scanner 5 according to its linear density.

The image memory 7 temporarily stores image data read by the scanner 5 as a file for memory transmission, or stores received image data in a plotter 6.
To temporarily store the file until it is recorded.

The encoding / decoding unit 8 converts the transmission image data into
While encoding and compressing with a predetermined coding method such as an MH coding method, an MR coding method, and an MMR coding method conforming to G3 facsimile, the received image data is subjected to an MH coding method.
The decoding is performed by a predetermined decoding method corresponding to the MR coding method, the MMR coding method, or the like.

The operation display section 9 is provided with ten keys for designating a destination facsimile number, a transmission start key, a one-touch dial key, a function key, and various other keys, and a display such as a liquid crystal display device. And displays the operating state of the device to be notified to the user and various messages.

The communication control unit 10 includes a facsimile modem as a component, modulates data to be transmitted to the line via the network control unit 11, and demodulates a signal received from the line via the network control unit 11, D corresponding to the dialed number
It transmits a TMF signal and detects various tone signals coming from the line, such as a dial tone, a ring tone, and a busy tone.

The network control unit 11 is connected to the line to close / release the DC loop of the line, detect the inversion of the line polarity,
It controls connection with a line, such as detection of line release, and generates dial pulses. The system bus 12 is a signal line through which the above components exchange data.

The facsimile apparatus 1 configured as described above performs the facsimile transmission / reception processing shown in FIGS.

First, in FIG.
Is an incoming call detected by the network control unit 11, or
It is monitored whether or not an original is set by an original sensor (not shown) of the scanner 5 (judgment 101).
No, No loop of judgment 102).

Then, when there is an incoming call (Ye in decision 101)
s) By controlling the network control unit 11 to close (off-hook) the line (process 103), a line with the transmission source device is established, and the facsimile reception process based on the G3 facsimile protocol is performed. The process is performed while monitoring whether or not a busy tone (busy tone) signal is detected by the control unit 10 (process 104, No in decision 105, No loop in decision 106).

When the facsimile reception process is completed (Yes in decision 106), the line is released (off-hook).
Then, the facsimile reception is terminated (process 107), but if a busy tone signal coming from the line (subscriber exchange) is detected during the facsimile reception process, that is, the transmission source goes on-hook during the facsimile transmission process for some reason. Also, if the line is disconnected (Yes in decision 105), the line is released (off-hook) and the facsimile reception is stopped (process 107).

If the original is set in the judgment 102 (Yes in the judgment 102), the process waits until a transmission destination is inputted (No loop in the judgment 108), and the transmission destination is displayed on the operation display unit 9 as a one-touch dial, a speed dial. Or
If the input is made by the manual dial (Yes in decision 108), the process waits until the start key for instructing the start of transmission is pressed (No loop in decision 109), and if the start key is pressed (Yes in decision 109), the line The communication control unit 10 detects a busy tone signal arriving from the (subscriber exchange) or monitors whether there is a response from the other party (line polarity reversal) (No in decision 111, No loop in decision 112) ).

If the busy tone is detected by the tone detector 10a while the other party is communicating or talking, the line is released (on-hook) and the facsimile transmission is stopped (process 116). When the response of the other party is detected (Yes in decision 112), the facsimile transmission process based on the G3 facsimile protocol is performed while the communication control unit 10 monitors whether a busy tone (busy tone) signal is detected. (Process 113, No of judgment 114, judgment 11
No. 5 loop).

When the facsimile transmission process is completed (Yes in decision 115), the line is released (off-hook).
Then, the facsimile transmission is terminated (process 116). However, if a busy tone signal coming from the line (subscriber exchange) is detected during the facsimile transmission process, that is, the other party goes on-hook during the facsimile reception process for some reason. Also, if the line is disconnected (Yes in determination 114), the line is released (on-hook) and the facsimile transmission is stopped (process 116).

As described above, when a busy tone signal is detected during facsimile transmission / reception, it is necessary to release a line to prevent occupation of an unnecessary line. However, a communication signal or the like which is not a busy tone signal coming from the line is required. If the erroneous detection is made as a busy tone signal, normal communication cannot be performed. Therefore, it is necessary to accurately detect the busy tone signal.

Further, after confirming a dial tone signal coming from the line (subscriber exchange) at the time of calling, facsimile transmission is started, or a ring tone signal coming from the line (subscriber exchange) at the time of calling is transmitted. In some cases, it is necessary to accurately detect the dial tone signal and the ring tone signal.

Tone signals such as a busy tone (busy tone) signal, a dial tone signal and a ring tone signal arriving from a local exchange of a line are basically 400 ± 19 Hz signals in Japan, and the dial tone signal is 400 ± 19 Hz continuous transmission, ringing tone signal and busy tone are 400 ±
This is a signal intermittently transmitted at 19 Hz. Therefore, the detection of various tone signals is performed by the subscriber exchange (facsimile apparatus 1).
Can be performed by detecting the signal of 400 ± 19 Hz arriving from the extension exchange when the is connected to the extension,
The type of each tone signal is the detected 400 ± 19H
This can be easily performed by measuring the lengths of the period during which the signal z is transmitted and the period during which the signal z is not transmitted.

FIG. 4 shows the configuration of the communication control unit 10.

In FIG. 1, a communication control unit 10 is connected to a line via a network control unit 11. The modem 10a of the communication control unit 10 exchanges communication signals with the line during communication, and when performing tone detection, a signal from the line is input to the tone detection unit 10aa. The signal from the line is also input to the frequency detector 10b of the communication controller 10, and the modem 10a and the frequency detector 10b output the detection result to the system controller 2 via the system bus 12.

FIG. 5 shows the tone detector 10aa and the frequency detector 10b of the modem 10a of the communication controller 10.

In the figure, an input signal from a line which is a signal to be detected is input to a tone detector 10aa and also to a binarization circuit (hysteresis comparator) 10ba of a frequency detector 10b. Binarization circuit 10
The binarized signal Sn output from ba is input to the frequency counter 10bb.
The frequency of the input signal is detected and the frequency counter 10bb
Notifies the system control unit 2 via the system bus 12 as a frequency determination result signal Sf as to whether or not the detected frequency is within a preset frequency range appropriate as a tone signal. Further, the tone detection unit 10aa
Whether the signal level of the input signal from the line is equal to or higher than a predetermined threshold level is notified to the system control unit 2 via the system bus 12 as a signal level determination result signal Sl.

FIG. 6 shows the configuration of the tone detector 10aa.

In the figure, an AGC circuit 20 generates a gain and amplifies an input signal so that the input signal is always output at a constant level of 0 dBm. For example, if the level of the input signal is −40 dBm, a gain of 40 dB is generated to normalize the input signal level to 0 dBm.
The AGC circuit 20 is turned on by the system control unit 2.
The AGC operation set to ON is performed by the / OFF setting signal, and if set to OFF, the input signal is output without amplification.

The band-pass filter 21 passes only a predetermined frequency band component of the input signal. The filter count storage unit 22 stores the filter count set by the system control unit 2, and the characteristics of the bandpass filter 21 are set by the filter count stored in the filter count storage unit 22.

The signal passing through the band-pass filter 21 is input to the power integrator 23, the signal power of which is calculated, and the output Sp from the power integrator 23 is input to the comparator 23,
The threshold value is compared with the threshold value stored in the threshold value storage unit 25 and set by the system control unit 2, and the result of the determination is output as a signal level determination result signal Sl.

The band-pass filter 21 is configured as shown in FIG. 7, and an input signal is input to a multiplier M1 and a filter coefficient 1
And the output of the multiplier M1 is input to the adder A1. The input signal is input to the delay line D1, and the output of the delay line D1 is input to the multiplier M2 and the delay line D2. The output of the delay line D1 and the filter count 2 are multiplied by the multiplier M2 and input to the adder A1. The output of the delay line D2 and the filter count 3 are multiplied by the multiplier M3 and input to the adder A1.

The output from the adder A 1 and the constant “2” are multiplied by the multiplier M 4 to become an output signal from the band-pass filter 21. The output from the multiplier M4 is input to the delay line D3, and the output from the delay line D3 is input to the multiplier M5 and the delay line D4.
Is input to The output of the delay line D3 and the filter count 5 are multiplied by the multiplier M5 and input to the adder A1. Output of delay line D4 and filter count 4
Is multiplied by the multiplier M6 and input to the adder A1.

The bandpass filter 2 configured as described above
The setting of various characteristics such as the center frequency of 1, the passband width, and the cutoff characteristics is performed by the system control unit 22 rewriting the values of the filter coefficients K1 to K5 stored in the filter count storage unit 22.

FIG. 8 shows the configuration of the power integrator 23.

In the figure, an input signal from the band-pass filter 21 is converted into an absolute value by an absolute value converter 30, input to a multiplier M10, multiplied by a count of 6, and output to an adder 10. The output from the adder becomes the output Sp from the power integrator 23 and is input to the comparator 24, while being input to the delay line D10. The output from the delay line D10 is input to the multiplier M11, multiplied by the coefficient 7, and input to the adder A10.

The tone detector 10 constructed as described above
aa filter coefficients 1 to 5 of the band-pass filter 21
When a coefficient stored in advance in the invalid coefficient table 3a shown in FIG. 9 is set, coefficients 2 to 5 other than the filter coefficient 1 set to 0.5 are set to 0, so that the feedback loop of the band-pass filter 21 is set. Are all 0, the input signal from the AGC circuit 20 is input to the power integrator 23 without being affected by the band pass filter 21.

Next, the procedure of tone detection processing in the facsimile machine 1 will be described with reference to FIGS.

In these figures, the system control unit 2
Waits for a factor to start tone detection to occur (No loop in decision 201).

When the judgments 105, 111, 114 and the like in the facsimile transmission / reception processing procedure shown in FIGS. 2 and 3 are performed, the judgment 201 becomes Yes, and the tone detector 10
The AGC circuit 20 is set to OFF (step 202), and the respective values of the invalid coefficient table 3a shown in FIG. 9 are set as the filter coefficients 1 to 5 of the band-pass filter 21 (step 203).

As a result, the input signal from the line is input to the power integrator 23 without being changed by the AGC circuit 20 and without being subjected to the band limitation by the band-pass filter 21. Become.

Further, the threshold value of the comparator 24 is set by writing the threshold value in the threshold value storage unit 25 (processing 2).
04), a timer Ts is started (process 205).
That is, the countdown of the time constant Ts is started.

The frequency determination result signal Sf from the frequency counter 10bb of the frequency detector 10b and the signal level determination result signal S1 from the tone detector 10aa are checked (steps 206 and 207). It is determined whether or not both the Sf and the signal level determination result signal Sl have become the H level (determination 208).
Is performed until timeout occurs (No loop of the judgment 209). If both the frequency determination result signal Sf and the signal level determination result signal Sl do not go to the H level and the timer Ts times out (Ye of the determination 209).
s) It is determined that the tone signal is not detected (process 210).

If both the frequency determination result signal Sf and the signal level determination result signal Sl become H level before the timer Ts times out (Ye of the determination 208).
s) Start the timer Td. That is, the countdown of the time constant Td is started (process 211).

Then, while confirming that both the frequency judgment result signal Sf and the signal level judgment result signal S1 are at the H level (decision 212), it waits for the timer Td to time out (No loop of decision 213).

If at least one of the frequency determination result signal Sf and the signal level determination result signal S1 is not at the H level before the timer Td times out (No in the determination 212), the process returns to the step 205. If the timer Td times out while both the frequency determination result signal Sf and the signal level determination result signal S1 are at the H level (Yes in determination 213), it is determined that a tone signal has been detected (process 214).

As a result, if the input signal has a frequency range appropriate for a tone signal and a signal level appropriate for a tone signal, it is detected as a tone signal.

That is, the input signals input to the tone detector 10aa and the frequency detector 10b shown in FIG. 12A are converted by the binarization circuit 10ba of the frequency detector 10b into the binary signals shown in FIG. It is output as the converted signal Sn. The frequency of the signal Sn is determined by the frequency counter 10bb.
And the frequency determination result signal Sf output from the frequency counter 10bb is H as shown in FIG. 3C only while the detected frequency is within a preset frequency range appropriate for a tone signal. Level. The output signal Sp from the power integrator 23 of the tone detector 10aa is as shown in FIG.
The signal level determination result signal Sl, which is a comparison result signal between the signal Sp and the threshold level, is as shown in FIG. As a result, as shown in FIG. 11F, the frequency determination result signal Sf becomes H level and the signal level determination result signal S1 becomes H level. Is determined as a tone signal.

However, as shown in FIG. 12 (e), the signal level determination result signal Sl is the power integrator 2 shown in FIG. 12 (d).
Due to the time delay caused by the integration constant of the output signal Sb from FIG. 3, the response to the input signal shown in FIG. 6A is delayed from the frequency determination result signal Sf in FIG.
Therefore, a time delay occurs in the detection of the tone signal. On the other hand, if the integration constant in the power integrator 23 is reduced to shorten the time delay of the signal level determination result signal Sl, the ripple of the power integration output increases and the comparator 24 malfunctions. A time delay of the result signal Sl is inevitable.

Therefore, instead of the tone detection processing procedure shown in FIGS. 10 and 11, the tone detection processing procedure shown in FIGS. 13 and 14 may be performed.

In FIGS. 13 and 14, the system control unit 2 waits for occurrence of a factor for starting tone detection (No loop in decision 301).

When the judgments 105, 111, 114 and the like in the facsimile transmission / reception processing procedure shown in FIGS. 2 and 3 are performed, the judgment 301 becomes Yes, and the tone detector 10
The AGC circuit 20 is set to OFF (process 302), and the values of the invalid coefficient table 3a shown in FIG. 9 are set as the filter coefficients 1 to 5 of the bandpass filter 21 (process 303).

Thus, the input signal from the line is input to the power integrator 23 without being changed by the AGC circuit 20 and without being restricted by the band-pass filter 21. Become.

Further, the threshold value of the comparator 24 is set by writing the threshold value in the threshold value storage unit 25 (process 3).
04), a timer Ts is started (process 305).
That is, the countdown of the time constant Ts is started.

Then, while checking the frequency determination result signal Sf from the frequency counter 10bb of the frequency detector 10b (process 306), it is determined whether the frequency determination result signal Sf has become H level (determination 307). The process is performed until the timer Ts times out (No loop of the determination 308). If the timer Ts times out without the frequency determination result signal Sf becoming H level (Yes in the determination 308), it is determined that the tone signal is not detected (Process 309).

If the frequency judgment result signal Sf becomes H level before the timer Ts times out (Yes in judgment 307), the timer Td is started. That is, the countdown of the time constant Td is started (processing 3
10).

The frequency determination result signals Sf are both H
While checking that the level is at the level (decision 311), it waits for the timer Td to time out (N of decision 312)
o loop).

If the frequency determination result signal Sf is not at the H level before the timer Td times out (No in the determination 311), the process returns to the step 305. If the timer Td times out while the frequency determination result signal Sf is at the H level (Yes in determination 312), the level of the signal level determination result signal Sl is confirmed (process 313).
As a result of the confirmation, when the signal level determination result signal Sl is not at the H level (No in the determination 314), the process returns to the process 305. If the signal level determination result signal Sl is at the H level (Yes in determination 314), it is determined that a tone signal has been detected (process 315).

As a result, the delay of the output of the signal level judgment result from the comparator 24 due to the time delay of the power integration in the power integrator 23 does not delay the detection of the tone signal. Detection can be performed.

As described above, according to the present embodiment, the frequency detector 10b determines whether the frequency of the input signal from the line is within a proper frequency range as a tone signal, and sets the coefficient of the modem 10a. Is temporarily changed, the AGC circuit 20 and the band-pass filter are invalidated, and the input signal is integrated by the power integrator 23 and compared with the threshold level by the comparator 24, whereby the input signal from the line is not valid as a tone signal. By judging whether it is above the threshold level,
It is possible to determine whether or not the input signal from the line is a tone signal. Further, the detection characteristic of the tone signal can be set by setting the frequency range in the frequency counter 10bb and setting the threshold level in the threshold value storage unit 25, and fine setting of the coefficient of the band-pass filter 21 is unnecessary. For,
It is possible to flexibly cope with differences in the characteristics of tone signals depending on the country or region where the facsimile machine 1 is installed.

In the embodiment described above, the present invention is applied to a facsimile apparatus which is one of the communication terminal apparatuses. However, the present invention is not limited to this, and performs data communication via a modem line. In addition, the present invention can be similarly applied to other communication terminal devices that need to detect a tone signal.

[0088]

According to the first aspect of the present invention, the detection target signal input to the band pass filter is input to the power integration means without being attenuated according to the frequency by the band pass filter. The power is integrated and input to the power comparing means. Thereby, by setting the predetermined threshold level in the power comparing means in advance,
It can be determined whether or not the level of the detection target signal is equal to or higher than the predetermined threshold level that satisfies the condition as a tone signal. Further, the band-pass filter, the power integrating means, and the power comparing means can be easily realized as a function of a modem originally provided in the communication terminal device for converting and demodulating a communication signal. As a result, an effect is obtained that the level detection of a tone signal having a frequency distant from the carrier signal frequency band can be performed at low cost. In addition, in the level detection of this method, since the demodulation processing unit of the modem is not used, there is an advantage that the variation of the level response due to the modulation / demodulation method does not occur.

According to the second aspect of the present invention, since the signal level determining means according to the first aspect is used for determining the level of the detection target signal, the frequency determination is performed for determining the level of the detection target signal. There is no need to provide a variable gain amplifier or the like in front of the means, and it is possible to obtain the effect that it is possible to perform tone detection under both frequency and level conditions at low cost. Further, since the setting change of the tone signal detection characteristic can be easily performed by setting the frequency range to the frequency determination unit, setting the threshold level to the power comparison unit, setting the duration, etc.
It is not necessary to prepare different hardware / software for each destination, and an effect is obtained that an inexpensive communication terminal device can be provided without deteriorating performance and functions.

According to the third aspect of the present invention, once the frequency determination means has determined that the frequency of the detection target signal is within the predetermined frequency range that is appropriate as a tone signal and has continued for a predetermined time, only once. The signal level determining means determines whether or not the signal level of the detection target signal is equal to or higher than the predetermined threshold level. Because of the necessity, the time delay of the determination is relatively unaffected by the time difference from the determination by the signal level determining means, and the integration time of the power integrating means can be lengthened. Accordingly, it is not necessary to forcibly shorten the integration time of the power integration means in accordance with the quickness of the determination by the frequency determination means, the power integration can be performed stably, and erroneous determination of the tone signal is less likely to occur. This has the effect that the tone signal can be detected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a block configuration of a facsimile apparatus as a communication terminal apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a facsimile transmission / reception procedure in the facsimile apparatus according to the embodiment of the present invention.

FIG. 3 is a flowchart together with FIG. 2 showing a facsimile transmission / reception processing procedure in the facsimile apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram showing a configuration and the like of a communication control unit of the facsimile apparatus according to the embodiment of the present invention.

FIG. 5 is a diagram showing a tone detector and a frequency detector of the facsimile apparatus according to the embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a tone detecting unit of the facsimile apparatus according to the embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a band-pass filter.

FIG. 8 is a diagram showing a configuration of a power integrator.

FIG. 9 is a diagram showing an invalid coefficient table.

FIG. 10 is a flowchart showing a tone detection processing procedure in the facsimile apparatus according to the embodiment of the present invention.

FIG. 11 is a flowchart, together with FIG. 10, showing a tone detection processing procedure in the facsimile apparatus according to the embodiment of the present invention.

FIG. 12 is a diagram showing a relationship between signals.

FIG. 13 is a flowchart showing another example of the tone detection processing procedure in the facsimile apparatus according to the embodiment of the present invention.

14 is a flowchart showing another example of the tone detection processing procedure in the facsimile apparatus according to the embodiment of the present invention, together with FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Facsimile apparatus 2 System control part 3 ROM 3a Invalid coefficient table 4 RAM 5 Scanner 6 Plotter 7 Image memory 8 Encoding / decoding part 9 Operation display part 10 Communication control part 10a Modem 10aa Tone detection part 10b Frequency detection part 10ba Binarization Circuit 10bb Frequency counter 11 Network control unit 12 System bus 20 AGC circuit 21 Bandpass filter 22 Filter coefficient storage unit 23 Power integrator 24 Comparator 25 Threshold storage unit M1, M2, M3, M4, M5, M6, M10, M11
Multiplier A1, A10 Adder D1, D2, D3, D4, D10 Delay line

Claims (3)

[Claims] 1. A frequency and a signal level of a detection target signal arriving from a line are determined, and the detection detection target signal is determined as a tone signal on condition that the frequency is equal to or higher than a predetermined frequency range and a threshold level. In a communication terminal device that operates, a band-pass filter to which a detection target signal coming from the line is input, power integration means for integrating signal power output from the band-pass filter, and output from the power integration means Power comparison means for comparing the power level of the band-pass filter with a predetermined threshold level, and the power level by the power comparison means when the coefficient group of the band-pass filter is temporarily set to a coefficient passing through the entire frequency band. Signal level determining means for determining whether the signal level of the detection target signal is equal to or higher than the predetermined threshold level based on the comparison result of Communication terminal apparatus characterized by comprising. 2. The detection target signal is converted into a binary signal by a binarizer, and the frequency of the binary signal from the binarizer is measured to determine whether or not the frequency is within a predetermined frequency range. Frequency determination means, wherein the frequency of the detection target signal is determined to be within the predetermined frequency range by the frequency determination means, and the signal level of the detection target signal is determined by the signal level determination means to the predetermined threshold level The communication terminal device according to claim 1, wherein the detection target signal is determined to be a tone signal on condition that the state determined as described above continues for a predetermined time. 3. The detection target signal is converted into a binary signal by a binarizer, and the frequency of the binary signal from the binarizer is measured to determine whether or not the frequency is within a predetermined frequency range. A signal level of the signal to be detected by the signal level determining means when a state in which the frequency of the signal to be detected is determined to be within the predetermined frequency range continues for a predetermined time. 2. The communication terminal device according to claim 1, wherein the detection target signal is determined to be a tone signal on condition that is determined to be equal to or higher than the predetermined threshold level.