JP3732348B2 - Communication terminal device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention comprises As The present invention relates to a communication terminal apparatus such as a facsimile apparatus including a tone detection apparatus.
[0002]
[Prior art]
In a communication terminal apparatus such as a facsimile apparatus, the line may have to be disconnected by detecting a busy sound signal coming from the line during communication.
[0003]
Specifically, in the facsimile apparatus, the other apparatus is communicating or talking at the time of automatic call, and the busy tone signal “Pup-Poo-Pu” from the subscriber exchange accommodating the facsimile apparatus is on the line. In some cases, the busy tone signal is detected, the line is released, and the line use efficiency is improved.
[0004]
Also, in a facsimile machine with an answering machine function, a voice message is received from a partner user that is received via the line when the user is away, and the partner user who has finished speaking speaks the handset of the partner device on-hook. When the line is disconnected, the busy tone signal sent from the subscriber exchange accommodating the facsimile device is detected, the voice message recording operation is terminated, and a useless signal (busy) In some cases, recording of sound signals) is not performed.
[0005]
Thus, a communication terminal apparatus that performs a predetermined operation as necessary when a busy signal on the line is detected must be able to accurately detect the busy signal on the line.
[0006]
In addition, it is necessary to be able to accurately detect a dial tone signal even when waiting for a response from the exchange by detecting a dial tone signal coming from the line when the phone is off-hooked. Also, by detecting a ringing tone signal coming from the line after sending a selection signal by dial pulse or DTMF signal off-hook when making a call, the ringing tone signal cannot be detected accurately even when checking the operation of the exchange. I must. Also, after sending a selection signal by going off-hook when making a call, the line must be disconnected by detecting the busy sound signal coming from the line because the other party specified by the selection signal is communicating There is.
[0007]
Since tone signals such as a busy tone signal, a dial tone signal, and a ringing tone signal sent to a certain communication terminal device via a line are sent from the subscriber exchange in which the communication terminal device is accommodated, A single tone signal can be accommodated in any subscriber switch in the circuit as long as the characteristics of the tone signals transmitted by all the subscriber switches are the same in all subscriber switches. The detection characteristic should be able to accurately detect the tone signal on the line.
[0008]
In a telephone line in Japan, a tone signal transmitted by a subscriber exchange is a signal of 400 ± 19 Hz, a dial tone signal is obtained by continuously transmitting a signal of 400 Hz ± 19 Hz, and a ringing tone signal is a signal of 400 Hz ± 19 Hz. Signal is modulated at a modulation rate of 85 ± 15% at a frequency of 15 Hz to 20 Hz, and the busy sound is a signal of 400 Hz ± 19 Hz with a make rate of 50% ± 10% and 60 cycles per minute ± Modulated by 20%.
[0009]
However, in some countries, the characteristics of the tone signal actually transmitted from the subscriber exchange in the circuit may not match the characteristics specified in that country. In addition to the characteristics, even if the tone signal detection characteristics of the tone detection device included in the communication terminal apparatus are set, the characteristics of the tone signal transmitted for each subscriber exchange in the line vary, and the communication terminal apparatus In some cases, the tone signal detection characteristic of the line does not match the characteristic of the tone signal transmitted by the subscriber exchange in which the communication terminal apparatus is accommodated, and the tone signal on the line cannot be detected.
[0010]
On the other hand, when the tone signal detection characteristics of the tone detector on the communication terminal side are wide, taking into account variations in the characteristics of the tone signal sent to each subscriber exchange in the line In some cases, the communication signal on the line or the voice of conversation is mistakenly detected as a busy tone signal, and the line is disconnected during communication, or the line is suddenly disconnected while recording a voice message. In some cases, malfunctions such as
[0011]
Also, not only when accommodated in telephone line subscriber exchanges, but also when accommodated in extension line exchanges, if there are variations in the characteristics of tone signals transmitted by the exchanges within the extension line, similar problems may occur. Occurs.
[0012]
Thus, accurately detecting a tone signal coming from a line regardless of the installation location of the apparatus is important for normal communication.
[0013]
On the other hand, with the recent spread of information communication such as facsimile communication, it has been desired to further reduce the price of communication terminal devices such as facsimile devices, but communication terminal devices such as facsimile devices are used in countries where they are used. Therefore, different operation specifications are required for each destination.
[0014]
Therefore, in order to reduce the cost of the equipment and meet the demand for lower prices, the hardware related to different operation specifications for each destination is designed as a common design, and each destination is set differently. Every It meets the required operating specifications.
[0015]
It is not an exception even in the tone detection device applied to the communication terminal device, and parameters for detecting the detection target signal coming from the line as a tone signal, specifically, the setting of the frequency range and the threshold of the detection level Is changed by a program so that tone signals having different characteristics for each destination can be accurately detected.
[0016]
In the tone detector, as a circuit configuration for determining whether or not the detection target signal coming from the line is a tone signal, the detection target signal is input to a band pass filter in which an appropriate frequency range is set as the tone signal. In addition, there is a configuration in which the power of the signal output from the band pass filter is compared with a predetermined threshold level to determine whether or not it is a tone signal, and for each destination of the tone signal detection characteristics Is set by setting the characteristics of the band-pass filter or setting the predetermined threshold value.
[0017]
The characteristics of the band-pass filter, specifically, the center frequency, the pass bandwidth, the cutoff characteristic, etc. can be set by changing the setting of the filter coefficient group. However, for example, even when two of the center frequency, the passband width, and the cutoff characteristic are fixed and the remaining one is changed, the filter coefficient group is configured. filter The coefficient value needs to be changed.
[0018]
In order to realize the desired filter characteristics of the bandpass filter, it is necessary to precisely calculate and actually verify each filter coefficient value constituting the filter coefficient group.
[0019]
Therefore, for each of a large number of filter characteristics that may be set for each destination, all corresponding filter coefficient groups are calculated, actually verified, and all filter coefficient groups are set in preparation for setting. Must be kept in memory.
[0020]
In addition to changing the setting of the filter characteristics for each destination, all filters corresponding to a number of filter characteristics can be used by service personnel to fine-tune various characteristics of the tone detection device at the actual installation location of each device. It is necessary to store the coefficient group in the memory.
[0021]
As another example of the circuit configuration for determining whether the detection target signal coming from the line is a tone signal in the tone detection device, the detection target signal is binarized by a hysteresis comparator or the like. There is a method of determining whether a detection target signal is within a predetermined frequency range by a frequency detector that measures a frequency of a signal after quantification using a frequency counter.
[0022]
[Problems to be solved by the invention]
In this method, the frequency range to be detected as a tone signal can be easily changed, but in order to change the threshold level to be detected as a tone signal for each destination, a variable gain amplifier is placed in front of the frequency detector. Etc., and cannot be realized at a low price.
[0023]
In addition, a modem device such as a facsimile modem includes an AGC circuit as a component for demodulating the received signal, and it is possible to calculate the level of the input signal from the amplification degree indicated by the AGC. In some cases, it reacts only to the carrier signal band to be demodulated and does not react to an input signal having a frequency band different from that of the carrier signal, such as a tone signal such as a dial tone.
[0024]
The present invention has been made in view of such circumstances, and can use a modem function to detect the level of a tone signal having a frequency away from the carrier signal frequency band at a low cost. It is an object of the present invention to provide a communication terminal device that can flexibly change detection characteristics.
[0025]
[Means for Solving the Problems]
In order to achieve the above object, the communication terminal apparatus according to claim 1 is an AGC unit that automatically adjusts and amplifies an input signal from a line so as to be always output at a constant level regardless of its level. From the band pass filter that passes only a predetermined frequency band component of the output signal from the AGC means, the power integration means that integrates the power of the output signal from the band pass filter, and the power integration means And a modem for demodulating a communication signal received from the line, and having at least power comparison means for comparing the output power signal of the output signal with a threshold level and outputting a comparison result, Judgment is made on the condition that the level is higher than the predetermined frequency range and threshold level. Departure In a communication terminal device that determines a signal as a tone signal and performs a predetermined operation, when determining whether the detection target signal coming from the line is a tone signal, the automatic gain adjustment function of the AGC means is turned off. The input signal is output as it is, the coefficient group of the band pass filter is set to a coefficient that passes through the entire frequency band, and a predetermined threshold for tone signal detection is set as a threshold level in the power comparison means. After setting a threshold level, signal level determination means for determining whether a signal level of the detection target signal is equal to or higher than the predetermined threshold level based on a comparison result of the power level by the power comparison means; 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 it is within a predetermined frequency range. Frequency determination means, wherein the frequency determination means determines that the frequency of the detection target signal is within the predetermined frequency range, and the signal level determination means sets the signal level of the detection target signal to the predetermined threshold. The detection target signal is determined as a tone signal on condition that the state determined to be equal to or higher than the level continues for a predetermined time.
[0026]
The communication terminal apparatus according to claim 2, wherein an AGC means for automatically adjusting and amplifying an input signal from a line so as to be always output at a constant level regardless of the level, and an output signal from the AGC means A band-pass filter that passes only a predetermined frequency band component, a power integrator that integrates the power of the output signal from the band-pass filter, and a threshold for the output power signal from the power integrator. A modem for demodulating a communication signal received from a line having at least power comparison means for outputting a comparison result compared with a level, and determining a frequency and a signal level of a detection target signal coming from the line, The test is performed on condition that the frequency range and threshold level are exceeded. Departure In a communication terminal device that determines a signal as a tone signal and performs a predetermined operation, when determining whether the detection target signal coming from the line is a tone signal, the automatic gain adjustment function of the AGC means is turned off. The input signal is output as it is, the coefficient group of the band pass filter is set to a coefficient that passes through the entire frequency band, and a predetermined threshold for tone signal detection is set as a threshold level in the power comparison means. After setting a threshold level, signal level determination means for determining whether a signal level of the detection target signal is equal to or higher than the predetermined threshold level based on a comparison result of the power level by the power comparison means; 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 it is within a predetermined frequency range. Frequency detection means, and the signal level determination means causes the signal of the detection target signal when a state in which the frequency determination means determines that the frequency of the detection target signal is within the predetermined frequency range continues for a predetermined time. The detection target signal is determined to be a tone signal on condition that the level is determined to be equal to or higher than the predetermined threshold level.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0029]
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.
[0030]
In the figure, 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 11, The system bus 12 is used.
[0031]
The system control unit 2 controls each unit of the apparatus while using the RAM 4 as a work area according to a control program written in the ROM 3.
[0032]
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.
[0033]
The RAM 4 is a random access memory used as a work area for the system control unit 2 as described above. Note that the RAM 4 is backed up by a backup circuit (not shown), and the stored contents are retained even when the apparatus power is shut off.
[0034]
The scanner 5 is for obtaining image data by reading a document image at a predetermined reading line density such as 3.85 lines / mm, 7.7 lines / mm, and 15.4 lines / mm. The plotter 6 records and outputs the received image data according to the linear density, and records and outputs the image data read by the scanner 5 according to the linear density (copy operation).
[0035]
The image memory 7 temporarily stores the image data read by the scanner 5 as a file for transmission to the memory, or temporarily stores the received image data as a file until it is recorded by the plotter 6. belongs to.
[0036]
The encoding / decoding unit 8 encodes and compresses transmission image data with a predetermined encoding method such as an MH encoding method, an MR encoding method, or an MMR encoding method that is compatible with G3 facsimile, while receiving image data. Is decoded and expanded by a predetermined decoding method corresponding to the MH encoding method, the MR encoding method, the MMR encoding method, or the like.
[0037]
The operation display unit 9 is provided with a numeric keypad 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. It displays the operating state of the device to be notified to the user and various messages.
[0038]
The communication control unit 10 includes a facsimile modem as a configuration and modulates data to be transmitted to the line via the network control unit 11, while demodulating a signal received from the line via the network control unit 11, A corresponding DTMF signal is transmitted, and various tone signals such as a dial tone, a ringing tone, and a busy tone coming from the line are detected.
[0039]
The network control unit 11 is connected to a line and performs connection control with a line such as closing / release of a DC loop of the line, detection of polarity reversal of the line, detection of line release, and generation of a dial pulse. It is. The system bus 12 is a signal line for the above units to exchange data.
[0040]
The facsimile apparatus 1 configured as described above performs facsimile transmission / reception processing shown in FIGS.
[0041]
First, in FIG. 2, the system control unit 2 monitors whether an incoming call is detected by the network control unit 11 or whether a document is detected by a document sensor (not shown) of the scanner 5. (No in decision 101, no loop in decision 102).
[0042]
When there is an incoming call (Yes in decision 101), the network control unit 11 is controlled to close the line (off-hook) (process 103), thereby establishing a line with the transmission source device and the G3 facsimile. Facsimile reception processing based on the protocol is performed while monitoring whether the busy tone signal is detected by the communication control unit 10 (processing 104, No in decision 105, No loop in decision 106).
[0043]
When the facsimile reception process is completed (Yes in decision 106), the line is opened (off hook) and the facsimile reception is terminated (process 107), but the busy tone coming from the line (subscriber exchange) during the facsimile reception process. When the signal is detected, that is, when the transmission source is on-hooked during the facsimile transmission process for some reason and the line is disconnected (Yes in decision 105), the line is released (off-hook) to receive the facsimile. Cancel (process 107).
[0044]
When the document is set in the determination 102 (Yes in the determination 102), the process waits until the transmission destination is input (No loop in the determination 108), and the transmission destination is displayed on the operation display unit 9 by the one-touch dial, speed dial, or When input is made by manual dialing (Yes at decision 108), the process waits until the start key for instructing transmission is pressed (No loop at decision 109). When the start key is pressed (Yes at decision 109), the line The communication control unit 10 detects a busy tone signal coming from (subscriber exchange) or monitors whether there is a response from the other party (inversion of line polarity) (No in decision 111, No loop in decision 112) ).
[0045]
When the other party is communicating or talking, and the tone detector 10a detects a busy tone, the line is released (on-hook) and facsimile transmission is stopped (step 116). When a response from the other party is detected (Yes in decision 112), facsimile transmission processing based on the G3 facsimile protocol is performed while monitoring whether a busy tone (busy tone) signal is detected by the communication control unit 10. (Process 113, No of decision 114, No loop of decision 115).
[0046]
When the facsimile transmission process is completed (Yes in decision 115), the line is released (off hook) and the facsimile transmission is terminated (process 116), but the busy tone coming from the line (subscriber exchange) during the facsimile transmission process. When a signal is detected, that is, when the other party on-hooks during the facsimile reception process for some reason and the line is disconnected (Yes in decision 114), the line is released (on-hook) and the facsimile transmission is performed. Cancel (process 116).
[0047]
As described above, when a busy tone signal is detected during facsimile transmission / reception, it is necessary to prevent the occupation of an unnecessary line by opening the line, but a communication signal that is not a busy tone signal coming from the line is used as a busy tone signal. If it is erroneously detected, normal communication cannot be performed, so it is necessary to accurately detect the busy tone signal.
[0048]
Also, facsimile transmission is started after confirming the dial tone signal coming from the line (subscriber exchange) at the time of outgoing call, or the ring tone signal coming from line (subscriber exchange) at the time of outgoing call is checked. In such a case, it is necessary to accurately detect the dial tone signal and the ring tone signal.
[0049]
In Japan, tone signals such as busy tone signals, dial tone signals, and ring tone signals coming from the subscriber exchange on the line are basically 400 ± 19 Hz signals, and the dial tone signals are 400 ± 19 Hz. The continuous transmission, the ringing tone signal and the busy tone are signals which are intermittently transmitted at 400 ± 19 Hz with a predetermined intermittent characteristic. Therefore, various tone signals can be detected by detecting a signal of 400 ± 19 Hz coming from a subscriber exchange (or an extension exchange when the facsimile apparatus 1 is connected to an extension). The detected signal of 400 ± 19Hz is sent out Has been This can be easily done by measuring the lengths of the period and the non-sent period.
[0050]
FIG. 4 shows the configuration of the communication control unit 10.
[0051]
In the figure, 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 at the time of communication. When tone detection is performed, a signal from the line is input to the tone detection unit 10aa. A signal from the line is also input to the frequency detection unit 10 b of the communication control unit 10, and the modem 10 a and the frequency detection unit 10 b output the detection result to the system control unit 2 via the system bus 12.
[0052]
FIG. 5 shows the tone detector 10aa and the frequency detector 10b of the modem 10a of the communication controller 10.
[0053]
In the figure, an input signal from a line, which is a detection target signal, is input to the tone detection unit 10aa and also input to a binarization circuit (hysteresis comparator) 10ba of the frequency detection unit 10b. The binarized signal Sn output from the binarization circuit 10ba is input to the frequency counter 10bb, the frequency of the input signal is detected by the frequency counter 10bb, and the detected frequency is preset in the frequency counter 10bb. The system controller 2 is notified via the system bus 12 as a frequency determination result signal Sf as to whether or not it is within a reasonable frequency range as a tone signal. Further, the tone detector 10aa determines whether or not the signal level of the input signal from the line is a signal equal to or higher than a predetermined threshold level set in advance via the system bus 12 as a signal level determination result signal S1. Notify the system control unit 2.
[0054]
FIG. 6 shows the configuration of the tone detector 10aa.
[0055]
In the figure, the AGC circuit 20 generates a gain and amplifies the 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 and the input signal level is normalized to 0 dBm. The AGC circuit 20 is set to ON by the ON / OFF setting signal from the system control unit 2. If done If the AGC operation is performed and set to OFF, the input signal is output without being amplified.
[0056]
The band pass filter 21 passes only a predetermined frequency band component of the input signal. filter coefficient The storage unit 22 is a filter set by the system control unit 2 coefficient Is stored in the filter coefficient Filter stored in the storage unit 22 coefficient Thus, the characteristics of the band pass filter 21 are set.
[0057]
The signal that has passed through the band pass filter 21 is input to the power integrator 23, the signal power is calculated, and the output Sp from the power integrator 23 is input to the comparator 23 and stored in the threshold value storage unit 25. The system control unit 2 compares and determines the threshold value, and the determination result is output as a signal level determination result signal Sl.
[0058]
The bandpass filter 21 has the configuration shown in FIG. 7, and an input signal is input to the multiplier M1, multiplied by a filter coefficient 1, and an 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 to the delay line D2. Delay line D1 output and filter coefficient 2 is multiplied by the multiplier M2 and input to the adder A1. Delay line D2 output and filter coefficient 3 is multiplied by the multiplier M3 and input to the adder A1.
[0059]
The output from the adder A1 and the constant “2” are multiplied by the multiplier M4 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 of the delay line D3 is input to the multiplier M5 and to the delay line D4. Delay line D3 output and filter coefficient 5 is multiplied by the multiplier M5 and input to the adder A1. Delay line D4 output and filter coefficient 4 is multiplied by the multiplier M6 and input to the adder A1.
[0060]
The setting of various characteristics such as the center frequency, the pass bandwidth, and the cutoff characteristic of the band pass filter 21 configured as described above is performed by the filter. coefficient This is done by the system control unit 22 rewriting the values of the filter coefficients K1 to K5 stored in the storage unit 22.
[0061]
FIG. 8 shows the configuration of the power integrator 23.
[0062]
In the figure, an input signal from the band pass filter 21 is converted into an absolute value by an absolute value converter 30 and input to a multiplier M10. coefficient 6 is output to the 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.
[0063]
When coefficients previously stored in the invalid coefficient table 3a shown in FIG. 9 are set as the filter coefficients 1 to 5 of the band-pass filter 21 of the tone detector 10aa configured as described above, the filter coefficient is set to 0.5. Since the coefficients 2 to 5 other than 1 are set to 0, the coefficients forming the feedback loop of the bandpass filter 21 are all 0. Therefore, the input signal from the AGC circuit 20 is affected by the bandpass filter 21. It is input to the power integrator 23 without being received.
[0064]
Next, a tone detection processing procedure in the facsimile apparatus 1 will be described with reference to FIGS.
[0065]
In these figures, the system control unit 2 waits for a factor to start tone detection to occur (No loop of decision 201).
[0066]
When judgments 105, 111, 114, etc. in the facsimile transmission / reception processing procedure shown in FIG. 2 and FIG. 3 are performed, judgment 201 becomes Yes, and the AGC circuit 20 of the tone detection unit 10aa is set to OFF (processing 202). Each value of the invalid coefficient table 3a shown in FIG. 9 is set as the filter coefficients 1 to 5 of the band pass filter 21 (process 203).
[0067]
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.
[0068]
Furthermore, the threshold value of the comparator 24 is set by writing the threshold value in the threshold value storage unit 25 (process 204), and the timer Ts is started (process 205). That is, the countdown of the time constant Ts is started.
[0069]
Then, while confirming the frequency determination result signal Sf from the frequency counter 10bb of the frequency detection unit 10b and the signal level determination result signal S1 from the tone detection unit 10aa (processing 206 and processing 207), the frequency determination result signal Sf and the signal It is determined whether or not both of the level determination result signals S1 have become the H level (determination 208), and is performed until the timer Ts times out (No loop of determination 209). If the timer Ts times out without both the frequency determination result signal Sf and the signal level determination result signal S1 becoming H level (Yes in determination 209), it is determined that the tone signal is not detected (processing 210).
[0070]
If both the frequency determination result signal Sf and the signal level determination result signal S1 become H level before the timer Ts times out (Yes in determination 208),
Timer Td is started. That is, the countdown of the time constant Td is started (process 211).
[0071]
Then, while confirming that both the frequency determination result signal Sf and the signal level determination result signal S1 are at the H level (determination 212), the control waits for the timer Td to time out (No loop of determination 213).
[0072]
If at least one of the frequency determination result signal Sf and the signal level determination result signal Sl is not at the H level before the timer Td times out (No in the determination 212), the process returns to step 205. When 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 the tone signal is detected (process 214).
[0073]
As a result, if the input signal is in a frequency range appropriate for a tone signal and a signal level appropriate for a tone signal, it is detected as a tone signal.
[0074]
That is, the input signals input to the tone detector 10aa and the frequency detector 10b shown in FIG. 12A are binarized as shown in FIG. 12B by the binarization circuit 10ba of the frequency detector 10b. Output as signal Sn. The frequency of the signal Sn is detected by the frequency counter 10bb, and the frequency determination result signal Sf output from the frequency counter 10bb is only when the detected frequency is set in advance and within a reasonable frequency range as a tone signal. It becomes H level as shown in FIG. Further, the output signal Sp from the power integrator 23 of the tone detector 10aa is as shown in FIG. 4D, and a signal level determination result signal which is a comparison result signal between the signal Sp by the comparator 24 and the threshold level. Sl is as shown in FIG. As a result, as shown in FIG. 5 (f), if the frequency determination result signal Sf becomes H level and the signal level determination result signal S1 becomes H level and the duration is equal to or greater than the time constant Td, the line Are determined as tone signals.
[0075]
However, as shown in FIG. 12 (e), the signal level determination result signal S1 has a time delay due to the integration constant of the output signal Sb from the power integrator 23 in FIG. The response to the input signal shown in FIG. 5A is delayed from the frequency determination result signal Sf. 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 decreased in order 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. The time delay of the result signal S1 is inevitable.
[0076]
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.
[0077]
13 and 14, the system control unit 2 waits for a factor to start tone detection to occur (No loop of determination 301).
[0078]
When judgments 105, 111, 114, etc. in the facsimile transmission / reception processing procedure shown in FIG. 2 and FIG. 3 are performed, the judgment 301 is Yes, and the AGC circuit 20 of the tone detection unit 10aa is set to OFF (processing 302). Each value of the invalid coefficient table 3a shown in FIG. 9 is set as the filter coefficients 1 to 5 of the band pass filter 21 (process 303).
[0079]
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.
[0080]
Furthermore, the threshold value of the comparator 24 is set by writing the threshold value in the threshold value storage unit 25 (process 304), and the timer Ts is started (process 305). That is, the countdown of the time constant Ts is started.
[0081]
Then, while confirming the frequency determination result signal Sf from the frequency counter 10bb of the frequency detector 10b (processing 306), it is determined whether or not the frequency determination result signal Sf has become H level (determination 307), and the timer Ts This is performed until time-out occurs (No loop of decision 308). If the timer Ts times out without the frequency determination result signal Sf becoming H level (Yes in decision 308), it is determined that the tone signal is not detected (processing 309).
[0082]
If the frequency determination result signal Sf becomes H level before the timer Ts times out (Yes in decision 307), the timer Td is started. That is, the countdown of the time constant Td is started (process 310).
[0083]
Then, while confirming that both frequency determination result signals Sf are at the H level (determination 311), the control waits for the timer Td to time out (No loop of determination 312).
[0084]
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 process 305. When the timer Td times out while the frequency determination result signal Sf is at the H level (Yes in decision 312), the level of the signal level determination result signal S1 is confirmed (processing 313). If the result signal S1 is not at the H level (No in decision 314), the process returns to step 305. When the signal level determination result signal S1 is at the H level (Yes in determination 314), it is determined that the tone signal is detected (processing 315).
[0085]
As a result, the tone signal can be detected quickly without delaying the detection of the tone signal due to the delay in the output of the signal level determination result from the comparator 24 due to the power integration time delay in the power integrator 23. .
[0086]
As described above, according to the present embodiment, the frequency detection unit 10b determines whether or not the frequency of the input signal from the line is within a reasonable frequency range as a tone signal, and the coefficient setting of the modem 10a is temporarily changed. Then, the AGC circuit 20 and the band-pass filter are disabled, the input signal is integrated by the power integrator 23, and compared with the threshold level by the comparator 24, so that the input signal from the line exceeds the threshold level that is appropriate as the tone signal. It is possible to determine whether or not the input signal from the line is a tone signal. The tone signal detection characteristics 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 band coefficient 21 setting is unnecessary. Therefore, it is possible to flexibly cope with the difference in tone signal characteristics depending on the country or region where the facsimile apparatus 1 is installed.
[0087]
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 line using a modem. The present invention can be similarly applied to other communication terminal devices that require signal detection.
[0088]
【The invention's effect】
Claim 1 According to the invention, the detection target signal input to the bandpass filter is input to the power integration unit without being attenuated according to the frequency by the bandpass filter, and is power-integrated, and the power comparison unit Is input. Accordingly, by setting the predetermined threshold level in the power comparing means in advance, it is 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. be able to. Also, It is a part of the modem function that the communication terminal device originally has for the conversion demodulation of the communication signal, Said AGC means, Band pass filter, power integration means, and power comparison means Can be used after a temporary setting change for tone signal determination. As a result, it is possible to obtain an effect that the level detection of the tone signal having a frequency away from the carrier signal frequency band can be performed at a low cost. In addition, the level detection of this method does not use the modem demodulation processing unit, and therefore has an advantage that variations in level reaction due to the modulation / demodulation method do not occur. Also, determine the level of the signal to be detected Before Since the signal level determination means is used, it is not necessary to place a variable gain amplifier or the like in front of the frequency determination means in order to determine the level of the detection target signal, and tone detection is performed at both low frequency and level conditions. The effect that can be done is obtained. Also, The tone signal detection characteristic setting can be easily changed by setting the frequency range in the frequency determination means, setting the threshold level in the power comparison means, setting the duration, etc. / There is no need to prepare software, and it is possible to provide an inexpensive communication terminal device without degrading performance / function.
[0089]
Claim 2 According to the invention according to In addition to the same effects as the invention according to claim 1, When the frequency determination means determines that the frequency of the detection target signal is within the predetermined frequency range valid as a tone signal and continues for a predetermined time from the first time, the signal level determination means performs the signal level detection signal only once. In order to determine whether the level is equal to or higher than the predetermined threshold level, the frequency determination means has a relatively small determination time delay. According Since it is necessary to perform power integration and the determination time delay is relatively large, it is not affected by the time difference between the determination by the signal level determination unit and the integration time of the power integration unit can be increased. Become. 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, power integration can be performed stably, and erroneous determination of the tone signal is less likely to occur. As a result, it is possible to detect the tone signal with high accuracy.
[Brief description of the drawings]
FIG. 1 is a block diagram 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 processing procedure in the facsimile apparatus according to the embodiment of the present invention.
FIG. 3 is a flowchart showing a facsimile transmission / reception processing procedure in the facsimile apparatus according to the embodiment of the present invention together with FIG. 2;
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 detection 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 showing a tone detection processing procedure in the facsimile apparatus according to the embodiment of the present invention, together with FIG. 10;
FIG. 12 is a diagram illustrating 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.
FIG. 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. 13;
[Explanation of symbols]
1 Facsimile device
2 System controller
3 ROM
3a Invalid coefficient table
4 RAM
5 Scanner
6 Plotter
7 Image memory
8 Coding / decoding unit
9 Operation display
10 Communication control unit
10a modem
10aa tone detector
10b Frequency detector
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 Multipliers
A1, A10 Adder
D1, D2, D3, D4, D10 Delay line

Claims (2)

AGC means for automatically adjusting and amplifying an input signal from the line so that it is always output at a constant level regardless of the level, and a predetermined frequency band component set in the output signal from the AGC means A bandpass filter that passes only the power, a power integrator that integrates the power of the output signal from the bandpass filter, and a power that outputs a comparison result by comparing the output power signal from the power integrator with a threshold level While having a modem having at least a comparison means and demodulating a communication signal received from the line, the frequency and signal level of the detection target signal coming from the line are determined, and the frequency is equal to or higher than a predetermined frequency range and threshold level. a communication terminal apparatus that performs a predetermined operation to the detection Detai elephants signal determines that the tone signal as a condition,
When determining whether the detection target signal coming from the line is a tone signal, the automatic gain adjustment function of the AGC means is turned off and the input signal is set to be output as it is, and the coefficient of the bandpass filter The group is set to a coefficient that passes through the entire frequency band, and further, a predetermined threshold level for tone signal detection is set as the threshold level in the power comparison unit, and then the power level comparison result by the power comparison unit Signal level determination means for determining whether the signal level of the detection target signal is equal to or higher than the predetermined threshold level;
Frequency detection means for converting the detection target signal into a binary signal by a binarizer, measuring the frequency of the binary signal from the binarizer, and determining whether or not the signal is within a predetermined frequency range; Prepared,
The frequency determination means determines that the frequency of the detection target signal is within the predetermined frequency range, and the signal level determination means determines that the signal level of the detection target signal is equal to or higher than the predetermined threshold level. A communication terminal apparatus, wherein the detection target signal is determined as a tone signal on condition that the state has continued for a predetermined time. AGC means for automatically adjusting and amplifying an input signal from the line so that it is always output at a constant level regardless of the level, and a predetermined frequency band component set in the output signal from the AGC means A bandpass filter that passes only the power, a power integrator that integrates the power of the output signal from the bandpass filter, and a power that outputs a comparison result by comparing the output power signal from the power integrator with a threshold level While having a modem having at least a comparison means and demodulating a communication signal received from the line, the frequency and signal level of the detection target signal coming from the line are determined, and the frequency is equal to or higher than a predetermined frequency range and threshold level. a communication terminal apparatus that performs a predetermined operation to the detection Detai elephants signal determines that the tone signal as a condition,
When determining whether the detection target signal coming from the line is a tone signal, the automatic gain adjustment function of the AGC means is turned off and the input signal is set to be output as it is, and the coefficient of the bandpass filter The group is set to a coefficient that passes through the entire frequency band, and further, a predetermined threshold level for tone signal detection is set as the threshold level in the power comparison unit, and then the power level comparison result by the power comparison unit Signal level determination means for determining whether the signal level of the detection target signal is equal to or higher than the predetermined threshold level;
Frequency detection means for converting the detection target signal into a binary signal by a binarizer, measuring the frequency of the binary signal from the binarizer, and determining whether or not the signal is within a predetermined frequency range; Prepared,
When the state where the frequency of the detection target signal is determined to be within the predetermined frequency range by the frequency determination unit continues for a predetermined time, the signal level of the detection target signal is set to the predetermined threshold by the signal level determination unit. A communication terminal apparatus, wherein the detection target signal is determined to be a tone signal on condition that the level is determined to be equal to or higher than a level.

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