JP2947273B1 - Control device and communication control device - Google Patents

Abstract

An external device that accurately determines the state of a control signal even when noise that repeats for a relatively long time on a transmission path and has unpredictable statistical properties is added to the control signal. A control device or a modem control device capable of controlling the operation of the device. The A modem control signal MC to the terminal apparatus 10 ₁ to 10 _N is output, the A / D converter 20, sampled at a sufficiently short sampling period than line clock CL generated based on the line speed information And quantize. Then, the adaptive filter section 21 performs adaptive signal processing on the quantized modem control signal MC, thereby removing noise N from the modem control signal MC. Thereby, the edge of the changing point of the modem control signal MC can be effectively extracted, and the state of the modem control signal MC can be accurately determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device and a communication control device for controlling the operation of an external device connected via a transmission line, and more particularly, to the operation of an external device connected via a transmission line. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device and a communication control device capable of removing noise added on a transmission path to a control signal transmitted / received to / from an external device for controlling and accurately determining a state of the control signal.

[0002]

2. Description of the Related Art FIG. 8 shows a basic configuration of a conventional communication system for collecting communication data from a terminal device using a telephone line. In this system, when a plurality of terminal devices 81 perform data communication with a host computer 82, first, a call signal CS is transmitted from each terminal device 81 through a modem 83 and an NCU (network control device) 84. Upon receiving the calling signal CS through the telephone line network 86 and the NCU 87, the telephone line modem 85 transmits a calling signal CI to the host computer 82. Host computer 82
Receives the call signal CI and receives the terminal device ready signal ER
To the modem 85. The modem 85 outputs a call signal CI
When the logical product is obtained, a line connection command CML is output to the NCU 87 to connect the line to each of the modems 83 and 85. As a result, the terminal device 81 and the host computer 82 are connected, and data communication becomes possible.

In the above-described system, each terminal device 81 is normally connected to an access point as a relay station via a telephone line network 86, and performs data communication with a host computer 82 through the access point (Japanese Patent Laid-Open No. Hei 2 (1994)). -213263).

[0004] In the data communication between the communication devices installed at distant places as described above, the modem device is designed to maintain the continuity of the signal reception mode even when the received signal is momentarily interrupted during the communication. An instantaneous interruption protection timer is provided.
However, there is a problem that the instantaneous interruption protection timer is activated immediately after data reception is completed, and noise is mixed into the received data during the operation period of the instantaneous interruption protection timer. Therefore, Japanese Patent Application Laid-Open No. 5-122267 prevents the noise from being mixed into the received data by detecting the disconnection of the transmission request signal output from the communication device on the data transmitting side by the modem device.

That is, as shown in FIG.
When 1 performs data communication with the communication device 92, the transmission data SD is transmitted to the modem device 93 and the transmission request signal RS is transmitted to the modem device 93. Upon receiving the transmission request signal RS, the modem device 93 generates a carrier signal CA by the carrier generation circuit 94, and the amplitude and phase modulator 95 amplitude-phase modulates the carrier signal CA in accordance with the transmission data SD and outputs the result. Further, the modem device 93 detects the disconnection of the transmission request signal RS output from the communication device 91 by the transmission request signal disconnection detection circuit 96, modulates the carrier signal CA with the detection signal CT, and transmits the modulated signal together with the modulation signal of the transmission data SD. , As a transmission signal CAS. The transmission signal CAS is transmitted via the transmission line 97 to the modem device 98 on the receiving side. The modem device 98 sends the transmission data SD in the transmission signal CAS to the communication device 92 as the reception data RD by the amplitude / phase demodulator 99, and the carrier wave detection circuit 100
To detect an instantaneous interruption of the transmission signal CAS. When the instantaneous interruption is detected, the instantaneous interruption protection timer 101 is activated, and the amplitude / phase modulator 99 performs a demodulation operation for a predetermined time (for example, 10n).
s) The continuity of the signal reception mode is maintained. At this time, when the control signal detection circuit 102 detects the detection signal CT, it is assumed that the reception of the transmission data SD has been completed, and the operation of the instantaneous interruption protection timer 101 is stopped. This prevents noise from being mixed into the received data RD immediately after the end of data reception.

In a communication system in which a plurality of terminal devices are connected to a packet multiplexing device via a transmission line, a transmission request signal RS is provided to control the communication operation of each terminal device.
And a modem control signal such as a transmission enable signal CS are transmitted and received via a transmission path. In such a communication system, a modem control signal transmitted from each terminal device to the packet multiplexer is sampled by inducing a transmission clock from the packet multiplexer to each terminal device.

However, when sampling the modem control signal due to the induction of the transmission clock, there is a problem that induced noise is generated and the state of the modem control signal is erroneously recognized. Japanese Patent No. 2697687 discloses a technique for preventing erroneous recognition of the state of a modem control signal due to the induced noise.

That is, as shown in FIG. 10, based on the line speed information on the transmission line, the time x from the change point of the transmission clock ST1 where the induction noise is synchronized to the point a which is not affected by the induction noise is calculated. Then, a sampling point for the modem control signal MC is determined. Furthermore,
The state of the modem control signal is determined according to whether or not the sampling result at this sampling point indicates the same state of the modem control signal continuously for the specified number of times.

[0009]

The latter two of the above-mentioned prior arts, when the statistical properties of the noise added to the signal transmitted through the transmission line are known, the transmission of this noise to the transmission signal. It is possible to eliminate the influence. However, in the case where noise due to disturbance on a transmission path, especially noise such as surge noise, which repeats for a relatively long time, and whose statistical properties are unpredictable, is added to the transmission signal, the above-mentioned known technique is used. Then, it was difficult to remove noise from the transmission signal.

As described above, when noise due to the above-described disturbance is added to a control signal such as a modem control signal transmitted through a transmission path, the control signal becomes unstable for a long time, and the control operation is performed. There is a problem that it may cause trouble.

SUMMARY OF THE INVENTION An object of the present invention is to accurately determine the state of a control signal even when noise which repeats for a relatively long time on a transmission path and whose statistical properties are unpredictable is added to the control signal. It is another object of the present invention to provide a control device or a modem control device capable of controlling the operation of an external device.

[0012]

According to the first aspect of the present invention, there is provided a method for controlling the operation of an external device connected via a transmission line via the transmission line with the external device. Sampling means for sampling the transmitted / received control signal at a sampling cycle shorter than the cycle corresponding to the line speed on the transmission line; and (b) an adaptive filter for removing noise from the sampled control signal by adaptive signal processing And means for determining the state of the control signal transmitted to and received from the external device based on the control signal from which the noise has been removed.

That is, in order to control the operation of an external device connected via a transmission line, a control signal transmitted / received via the transmission line to / from the external device is controlled based on a period corresponding to a line speed on the transmission line. Are also sampled with a short sampling period,
Noise is removed from the sampled control signal by adaptive signal processing, and the state of the control signal transmitted to and received from an external device is determined based on the control signal from which the noise has been removed. Thereby, the control signal transmitted / received to / from the external device is a noise generated by disturbance on the transmission path,
In particular, even when the noise is repeatedly generated for a relatively long time, such as surge noise, and is affected by noise whose statistical properties are unpredictable, the influence of the noise on the control signal is reliably removed, and the control signal is removed. Effectively extract the edge of the change point of
The state of the modem control signal can be accurately determined.

Further, according to the invention of claim 2, (a) a control transmitted / received via the transmission line to / from the external device to control an operation of the external device connected via the transmission line. First sampling means for sampling a signal at a sampling cycle shorter than the cycle corresponding to the line speed on the transmission line; and (b) adaptive filter means for removing noise from the sampled control signal by adaptive signal processing. (C) second sampling means for sampling the control signal from which the noise has been removed at a sampling period corresponding to the line speed, and (d) the control signal thus sampled continuously for a predetermined number of times. Determining means for determining a state of a control signal transmitted / received to / from the external device according to whether or not the same state of the control signal is indicated; .

That is, in order to control the operation of an external device connected via a transmission line, a control signal transmitted / received to / from the external device via the transmission line is controlled by a period corresponding to a line speed on the transmission line. Are also sampled with a short sampling period,
Noise is removed from the sampled control signal by adaptive signal processing, and the control signal from which the noise has been removed is sampled at a sampling period corresponding to the line speed.
The state of the control signal transmitted / received to / from the external device is determined according to whether or not the sampled control signal indicates the same state of the control signal continuously for a predetermined number of times of sampling. Thus, in addition to the effect of the first aspect, even when the level of the control signal temporarily largely fluctuates due to the influence of noise, the state of the control signal can be accurately determined.

Further, in the control device according to the first or second aspect, the adaptive filter means has a FIR (finite impulse response) digital filter, and determines a filter coefficient of the FIR digital filter according to an adaptive algorithm. It may be.

Further, in the control device according to the present invention, the adaptive filter means has an IIR (infinite impulse response) digital filter, and determines a filter coefficient of the IIR digital filter according to an adaptive algorithm. It may be. This allows
Even when a relatively low-order digital filter is used, a high convergence speed of the filter coefficient can be achieved, so that the effect of removing noise by the adaptive filter means can be easily improved.

According to the third aspect of the present invention, (a) a modem control signal transmitted / received to / from the terminal device for controlling a communication operation of the terminal device connected via the transmission line is transmitted on the transmission line. Sampling means for sampling at a sampling cycle shorter than the cycle corresponding to the line speed of (b)
(C) adaptive filter means for removing noise from the sampled modem control signal by adaptive signal processing;
The communication control device is provided with determining means for determining the state of the modem control signal transmitted from the terminal device based on the modem control signal from which the noise has been removed.

That is, a modem control signal transmitted / received to / from a terminal device for controlling a communication operation of the terminal device connected via the transmission line has a sampling period shorter than a period corresponding to a line speed on the transmission line. , And noise is removed from the sampled modem control signal by adaptive signal processing. Based on the modem control signal from which the noise has been removed, the state of the modem control signal transmitted from the terminal device is determined. As a result, the modem control signal transmitted / received to / from the terminal device repeats for a relatively long time, such as noise generated by disturbance on the transmission path, particularly surge noise, and the statistical property is unpredictable. Even when the control signal is affected by noise, the influence of the noise on the modem control signal is reliably removed, the edge of the control signal change point is effectively extracted, and the state of the modem control signal is accurately determined. be able to.

Further, according to the invention of claim 4, (a) a modem control signal transmitted / received to / from the terminal device for controlling a communication operation of the terminal device connected via the transmission line is transmitted on the transmission line. First sampling means for sampling at a sampling cycle shorter than a cycle corresponding to the line speed of
(B) adaptive filter means for removing noise from the sampled modem control signal by adaptive signal processing;
(C) second sampling means for sampling the noise-removed modem control signal at a cycle corresponding to the line speed, and (d) the same number of times that the sampled modem control signal is continuously sampled for the same number of times. The communication control device is provided with determining means for determining the status of the modem control signal output from the terminal device according to whether or not the status of the modem control signal is indicated.

That is, in order to control a communication operation of a terminal device connected via a transmission line, a modem control signal transmitted / received to / from the terminal device has a sampling rate shorter than a cycle corresponding to a line speed on the transmission line. The sampled modem control signal is sampled at a cycle corresponding to the line speed, the noise is removed by adaptive signal processing from the sampled modem control signal, and the sampled modem control signal is sampled at a cycle corresponding to the line speed. The state of the modem control signal output from the terminal device is determined depending on whether or not the same state of the modem control signal continues for a predetermined number of samplings. Thus, in addition to the effect of the third aspect of the present invention, even when the level of the modem control signal temporarily fluctuates greatly due to the influence of noise, the state of the modem control signal can be accurately determined.

[0022] According to the fifth aspect of the present invention, the third aspect is provided.
5. The communication control device according to claim 4, wherein said adaptive filter means includes an FIR digital filter, and a filter coefficient of said FIR digital filter is determined according to an adaptive algorithm.

According to the sixth aspect of the present invention, there is provided the third aspect.
5. The communication control device according to claim 4, wherein the adaptive filter means has an IIR digital filter, and determines a filter coefficient of the IIR digital filter according to an adaptive algorithm. This allows
Even when a relatively low-order digital filter is used, a high convergence speed of the filter coefficient can be achieved, so that the effect of removing noise by the adaptive filter means can be easily improved.

[0024]

Embodiments of the present invention will be described below in detail.

FIG. 1 shows a schematic configuration of a communication system including a control device or a communication control device according to an embodiment of the present invention.

In this communication system, a plurality of terminal devices 10 ₁ to 10 _N as external devices are connected to a packet multiplexing device 12 via a line cable 11 as a transmission line. This packet multiplexing device 12 is connected to a host device 15 via a network 14. These first to N-th terminal devices 10 ₁ to 10 _N transmit communication data to the packet multiplexing device 12 via the line cable 11, and transmit a modem control signal via the line cable 11 to the packet multiplexing device 12. And send and receive. The modem control signals, packet multiplexing apparatus 12 is the terminal apparatus 10 ₁ to 10 _N
It is a control signal such as a transmission request signal and transmit enable signal which is transmitted and received between the terminal apparatus 10 ₁ to 10 _N for controlling the communication operation.

The packet multiplexer 12 is a terminal device 10 ₁
The communication data transmitted from _N to 10 _N is multiplexed and transmitted to the host device 15 via the network 14. The packet multiplexer 12 has a plurality of modem control signal state detector 13 ₁ to 13 _N. These first to Nth modem control signal state detectors 13 _{1 to} 13 _N are for detecting the state of the modem control signal and have the same configuration. An arrow N in the figure indicates noise added to a signal transmitted by the line cable 11.

FIG. 2 shows the internal configuration of the first modem control signal state detector. First modem control signal state detector 13
₁ has an analog / digital converter (hereinafter, referred to as an A / D converter) 20 as sampling means. Modem control signal MC to the terminal apparatus 10 ₁ to 10 _N is output is input via the line cable 11 to the A / D converter 20.
The A / D converter 20 samples the modem control signal MC at a sampling period sufficiently shorter than the line clock CL generated based on the line speed information on the line cable 11. The sampling in the A / D converter 20 is executed in synchronization with a clock (hereinafter, referred to as a clock h) obtained by dividing an initial clock generated by an oscillator (not shown) to a frequency higher than the line clock CL. It is desirable that the frequency of the clock h be at least twice the maximum frequency of the frequency component of the noise to be removed. However, the upper limit of the frequency of the clock h is defined by the signal processing capability of the packet multiplexer 12 and the number of calculation steps of the adaptive algorithm described later. In consideration of this point, the cycle of the clock h is 1 / the cycle of the line clock CL.
It is preferred to be about 10.

The modem control signal sampled in this way is quantized by the A / D converter 20 and converted into time-series data 20 '. This time-series data 20 'is input to an adaptive filter unit 21 as adaptive filter means. The adaptive filter unit 21 removes noise from the time series data 20 'of the modem control signal by adaptive signal processing. The time-series data 21 ′ from which the noise has been removed is output to the comparing unit 22. The comparison unit 22 calculates the time-series data 2
1 ′ is compared with a predetermined threshold value LR and converted into binary data indicating a high level or a low level. this is,
Binary data 22 'indicating ON / OFF of the modem control signal
It is. The binary data 22 'indicating ON / OFF of the modem control signal is input to a judgment unit 23 as judgment means. The determination unit 23 determines the state of the modem control signal MC based on the binary data 22 'input from the comparison unit 22, and outputs a signal 23' indicating the determination result.

FIG. 3 shows the internal configuration of the adaptive filter unit. As shown in the figure, the adaptive filter unit 21 has an n-th order FIR (finite impulse response) digital filter 30.
Having. This FIR digital filter 30 has n number of delay elements 31 _{1 to} 31 _n connected in series. Each of the delay elements 31 _{1 to} 31 _n delays the input signal by one cycle of the clock h, and outputs the n multipliers 32 ₁ to 32 n.
32 _n respectively. Each multiplier 32 ₁ to 32 _n is input from the delay element 31 ₁ to 31 _n respectively corresponding signal, in order to perform the weighting, the filter coefficients A ₁ to A _n supplied from the adaptive algorithm operating portion 36, respectively The result is multiplied and output to the adder 33.

The FIR digital filter 30 has a multiplier 32 _0. The multiplier 32 ₀ converts the filter coefficient A ₀ supplied from the adaptive algorithm operation unit 36 to A / A
A signal directly input from the D converter 20 is multiplied and output to the adder 33. The adder 33 calculates the sum of all output signals of the multipliers 32 _{0 to} 32 _n , and outputs a signal 21 ′ indicating the result of the calculation to the comparing unit 22 and the subtracting unit 34.

The adaptive filter section 21 has a delay element 35 for generating reference data SA for the output signal 21 ′ of the FIR digital filter 30. A / D delayed by one cycle of clock h by this delay element 35
The output signal 20 'of the converter 20 (see FIG. 2) is output to the subtractor 34 as reference data SA. The subtractor 34 calculates an error between the output signal 21 ′ of the adder 33 and the output signal SA of the delay element 35. In the adaptive algorithm operating portion 36, this so that the error value approaches "0", the filter coefficient A ₀ to A _n which is supplied to respective multipliers 32 ₀ to 32 _n in accordance with the adaptive algorithm for each one cycle of the clock h is operational Is done. The calculated value is in synchronism with the clock h, it is output corresponding to each of the multipliers 32 ₁ to 32 _n, each multiplier 32 _1-3
The 2 _n filter coefficients A _{0 to An} are updated in synchronization with the clock h.

The signal 21 'output from the adder 33 to the comparing section 22 shown in FIG. 2 is compared with a predetermined threshold value LR in the comparing section 22 to determine whether the modem control signal is ON or OFF.
It is converted into binary data 22 ′ indicating OFF,
Is output to

FIG. 4 shows the internal configuration of the determination unit. The determination unit 23 determines whether the modem control signal MC from the comparison unit 22 is on or not.
Second sampling of binary data 22 'indicating OFF
Has a sampling control section 40 as a sampling means. In the sampling control section 40, the signal 22 'from the comparison section 22 is sampled in synchronization with the line clock. This sampling result is
The values are sequentially stored in the m-th (for example, m = 3) registers 41 _{1 to} 41 _m , and the stored values are sequentially updated each time a new sampling result is obtained. And the first to m-th
State determination unit 42 determines the state of the modem control signal based on the values of the data stored in the registers 41 _{1 to} 41 _m .

That is, when the values of the data stored in the _m registers 41 _{1 to} 41 _m all match, the state of the modem control signal MC corresponding to this value is recognized as the current state of the modem control signal MC. . Also, m registers 41 ₁
If all the data values stored in .about.41 _m do not match, the recognition result one clock cycle before is held as the current state of the modem control signal MC. Thus, the state of modem control signal MC is determined according to whether or not the result of sampling by sampling control section 40 indicates the same state of modem control signal MC continuously for a predetermined number of times of sampling. The signal 23 ′ indicating this determination result is notified to the CPU (Central Processing Unit) of the packet multiplexing device 12 as a higher function unit via the state holding / notifying unit 43.

Next, the operation of the modem control signal determination device will be described.

FIG. 5 is a flowchart showing the flow of the process for determining the state of the modem control signal executed by the CPU of the packet multiplexer. First, modem control signal MC to the terminal apparatus 10 ₁ to 10 _N is output, sufficient cycles are sampled synchronously with the shorter clock h than line clock CL (step S101). The sampled modem control signal MC is quantized by the A / D converter 20 and converted into time-series data 20 '(step S10).
2).

Next, the time-series data 20 'is input to the adaptive filter unit 21 and, according to the above-described configuration, sampling for the past (n + 1) times from the latest sampling result to the sampling result n cycles before the clock h. Depending on the result, noise is removed by adaptive signal processing (step S103). The time-series data 21 'of the modem control signal from which the noise has been removed in this manner is compared with a predetermined threshold value LR in the comparator 22, and converted into binary data 22' indicating ON / OFF of the modem control signal MC. Is performed (step S104).

The binary data 22 'is sampled by the sampling control section 40 in synchronization with the line clock CL, and stored in the _first to m-th registers 41 _{1 to} 41 _m of the determination section 23 based on the sampling result. The updated values are sequentially rewritten (step S105). Then, it is determined whether all the values stored in the _first to m-th registers 41 _{1 to} 41 _m match (step S10).
6). Here, when all the values match, the state of the modem control signal MC corresponding to this value is recognized as the current state of the modem control signal MC (step S107), and this processing ends. When all the values do not match, the state recognized one clock before is recognized as the current state of the modem control signal MC (step S108), and this processing ends. Thus, the state of the modem control signal MC is determined according to whether or not the time-series data 22 'sampled in synchronization with the line clock CL indicates the same state of the modem control signal MC continuously for a predetermined number of times. Is done.

FIG. 6 shows a change in the modem control signal in the above-described process of determining the state of the modem control signal.

FIG. 6A shows a modem control signal MC to which noise is added on the line cable 11. FIG. 6 (b)
6A shows time-series data 20 ′ obtained by sampling the modem control signal MC shown in FIG. 6A in synchronization with the clock h and quantizing it in the A / D converter 22. FIG. 6C shows a signal 21 ′ obtained by removing noise from the time-series data of FIG. 6B by adaptive signal processing in the adaptive filter unit 21. Further, the dotted line in the figure indicates the level of the threshold LR that is compared in the comparison unit 22 with the signal 21 ′ obtained by removing the noise.
FIG. 6D shows the time series data 22 ′ of the modem control signal MC binarized by the comparison unit 22 by the line clock C.
A sampling point at which sampling is performed in synchronization with L is indicated by an arrow SP. FIG. 6E shows the modem control signal MC whose state has been determined by the determination unit 23 based on the signal sampled at the sampling point SP shown in FIG. 6D. “OFF” in the figure indicates that the modem control signal MC is at a low potential and is in an off state. “ON” indicates that the modem control signal MC is at a high potential and is in an ON state.

[0042] As described above, the control apparatus of the present embodiment, a modem control signal M by the terminal device 10 ₁ to 10 _N is output
C is sampled by the A / D converter 20 at a sampling period sufficiently shorter than the line clock CL generated based on the line speed information. Then, the adaptive filter section 21 performs adaptive signal processing on the sampled modem control signal 20 ′ to remove noise from the modem control signal MC. This allows
Since the edge of the changing point of the modem control signal MC can be effectively extracted, the state of the modem control signal MC can be accurately determined.

Further, binary data 22 'indicating ON / OFF of the modem control signal MC output from the comparing section 22 is sampled in synchronization with the line clock CL. The determination unit 23 determines the state of the modem control signal MC according to whether or not the sampling result indicates the same state of the modem control signal MC continuously for a predetermined number of times of sampling. Accordingly, even when the level of the modem control signal MC temporarily fluctuates greatly due to the influence of noise, the state of the modem control signal MC can be accurately determined.

In the above-described embodiment, the adaptive filter section 21 has the FIR digital filter 30. However, the present invention is not limited to this.

FIG. 7 shows a case where the adaptive filter section 21 has a configuration having an IIR (infinite impulse response) digital filter 60. Thus, the adaptive filter unit 21
Has an IIR digital filter 60, so that the filter coefficients can be converged more rapidly than in the case of using FIR digital filters of the same order. For this reason, it is easy to improve the effect of noise removal in the adaptive filter unit 21.

In the above-described embodiment, an example has been described in which the control device is a packet multiplexing device. However, the present invention is not limited to this. INDUSTRIAL APPLICABILITY The present invention is applicable to all control devices that are connected to an external device via a transmission path and that transmit and receive control signals for controlling the external device via the transmission path.

Although the present invention is suitable for a system for transmitting a control signal by a baseband system, it is particularly suitable for preventing erroneous recognition of the state of the control signal when transmitting the control signal by a single-flow system. It is.

[0048]

As described above, according to the first aspect of the present invention, transmission / reception to / from an external device via a transmission line is performed to control the operation of an external device connected via the transmission line. Control signal is sampled at a sampling cycle shorter than the cycle corresponding to the line speed on the transmission line, noise is removed from the sampled control signal by adaptive signal processing, and the control signal from which the noise has been removed is converted to a control signal. The state of the control signal transmitted to and received from the external device is determined based on the determination. As a result, the control signal transmitted / received to / from the external device repeatedly occurs for a relatively long time, such as noise generated by disturbance on the transmission line, particularly surge noise, and the statistical property is unpredictable. Even when affected by noise, it is possible to accurately remove the influence of noise on the control signal, extract the edge of the control signal change point effectively, and accurately determine the state of the modem control signal. it can.

According to the second aspect of the present invention, a control signal transmitted / received to / from an external device via a transmission line to control the operation of the external device connected via the transmission line is: Sampling is performed at a sampling cycle shorter than the cycle corresponding to the line speed on the transmission line, noise is removed from the sampled control signal by adaptive signal processing, and the control signal from which the noise has been removed is a sample corresponding to the line speed. The state of the control signal transmitted / received to / from the external device is determined according to whether or not the sampled control signal indicates the same state of the control signal continuously for a predetermined number of times of sampling. You. Accordingly, in addition to the effect of the first aspect, even when the level of the control signal temporarily fluctuates greatly due to the influence of noise,
The state of the control signal can be accurately determined.

According to the third aspect of the present invention, a modem control signal transmitted / received to / from a terminal device for controlling a communication operation of the terminal device connected via the transmission line has a line speed on the transmission line. , A noise is removed from the sampled modem control signal by adaptive signal processing, and a modem control transmitted by a terminal device based on the noise-removed modem control signal. The state of the signal is determined. As a result, the modem control signal transmitted / received to / from the terminal device repeats for a relatively long time, such as noise generated by disturbance on the transmission path, particularly surge noise, and the statistical property is unpredictable. Noise,
The influence of noise on the modem control signal can be reliably removed, and the edge of the control signal change point can be effectively extracted to accurately determine the state of the modem control signal.

According to the fourth aspect of the present invention, a modem control signal transmitted / received to / from the terminal device for controlling a communication operation of the terminal device connected via the transmission line is transmitted through a line on the transmission line. Sampling is performed at a sampling period shorter than the period corresponding to the speed, noise is removed from the sampled modem control signal by adaptive signal processing, and the modem control signal from which the noise has been removed is sampled at a period corresponding to the line speed. Then, the state of the modem control signal output from the terminal device is determined according to whether or not the sampled modem control signal continuously shows the same state of the modem control signal a predetermined number of times. Thus, in addition to the effect of the third aspect of the present invention, even when the level of the modem control signal temporarily fluctuates greatly due to the influence of noise, the state of the modem control signal can be accurately determined.

According to the fifth aspect of the present invention, the adaptive filter means has an FIR digital filter, and determines a filter coefficient of the FIR digital filter according to an adaptive algorithm.

According to the invention of claim 6, the adaptive filter means has an IIR digital filter, and determines a filter coefficient of the IIR digital filter according to an adaptive algorithm. As a result, a high convergence speed of the filter coefficient can be achieved even when a relatively low-order digital filter is used, so that the effect of noise removal by the adaptive filter means can be easily improved.

[Detailed description of drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a communication system including a modem control signal determination device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a modem control signal state detection unit according to one embodiment of the present invention.

FIG. 3 is a block diagram illustrating an internal configuration of an adaptive filter unit according to one embodiment of the present invention.

FIG. 4 is a block diagram illustrating an internal configuration of a determination unit according to one embodiment of the present invention.

FIG. 5 is a flowchart showing a flow of a process for determining a state of a modem control signal.

FIG. 6 is an explanatory diagram showing a change in a modem control signal due to the processing of FIG. 5;

FIG. 7 is a block diagram showing another embodiment of the internal configuration of the adaptive filter unit.

FIG. 8 is a block diagram showing a schematic configuration of a conventional communication system for collecting communication data from a terminal device via a telephone line network.

FIG. 9 is a block diagram illustrating a schematic configuration of a communication system including a conventional noise removing device.

FIG. 10 is an explanatory diagram illustrating a conventional method for removing noise from a modem control signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Terminal device 11 Line cable 12 Packet multiplexer 13 Modem control signal state detection unit 20 A / D converter 21 Adaptive filter unit 22 Comparison unit 23 Judgment unit 30 FIR digital filter 31, 35 Delay element 32 Multiplier 33 Adder 34 Subtractor 36 Adaptive algorithm operation unit 40 Sampling control unit 41 Register 42 State determination unit 50 IIR digital filter

Continuation of the front page (51) Int.Cl. ⁶ identification code FI H04M 11/00 302 H04M 11/00 302 H04Q 3/42 104 H04Q 3/42 104 (58) Investigated field (Int.Cl. ⁶ , DB name) H04B 1/10 H04B 15/00 H03H 17/00-21/00 H04B 3/06 H04M 11/00 H04Q 3/42

Claims (6)

(57) [Claims] 1. A control signal transmitted / received via the transmission line to / from the external device for controlling the operation of the external device connected via the transmission line corresponds to a line speed on the transmission line. Sampling means for sampling at a sampling cycle shorter than the cycle to be performed; adaptive filter means for removing noise from the sampled control signal by adaptive signal processing; and the external device based on the control signal from which the noise has been removed. A determination unit for determining a state of a control signal transmitted and received between the control device and the control device. 2. A control signal transmitted / received via the transmission line to / from the external device for controlling the operation of the external device connected via the transmission line corresponds to a line speed on the transmission line. First sampling means for sampling at a sampling cycle shorter than the sampling cycle, adaptive filter means for removing noise from the sampled control signal by adaptive signal processing, and transmitting the control signal from which the noise has been removed to the line speed A second sampling means for sampling at a sampling period corresponding to the following, and the external device according to whether or not this sampled control signal continuously shows the same state of the control signal a predetermined number of times of sampling A control unit for determining a state of a control signal transmitted and received between the control unit and the control unit. 3. A modem control signal transmitted / received to / from a terminal device for controlling a communication operation of the terminal device connected via a transmission line is shorter than a cycle corresponding to a line speed on the transmission line. Sampling means for sampling at a sampling period; adaptive filter means for removing noise from the sampled modem control signal by adaptive signal processing; and a modem transmitted by the terminal device based on the modem control signal from which the noise has been removed. A communication control device comprising: a determination unit configured to determine a state of a control signal. 4. A modem control signal transmitted / received to / from a terminal device for controlling a communication operation of the terminal device connected via the transmission line is shorter than a cycle corresponding to a line speed on the transmission line. First sampling means for sampling at a sampling period, adaptive filter means for removing noise from the sampled modem control signal by adaptive signal processing, and the modem control signal from which the noise has been removed corresponds to the line speed. Second sampling means for sampling periodically, and modem control output by the terminal device according to whether or not the sampled modem control signal continuously shows the same state of the modem control signal for a predetermined number of times of sampling. A communication control device comprising: a determination unit configured to determine a state of a signal. 5. The modem control signal judging device according to claim 3, wherein said adaptive filter means has an FIR digital filter, and determines a filter coefficient of said FIR digital filter according to an adaptive algorithm. . 6. The control device according to claim 3, wherein said adaptive filter means has an IIR digital filter, and determines a filter coefficient of said IIR digital filter according to an adaptive algorithm.