JPH0393343A - Data communication equipment - Google Patents

Abstract

PURPOSE:To improve the sureness of communication by measuring the predicted effect of background noise onto the communication while detecting a prescribed signal of an opposite station before data transmission after connection of a communication line to control the communication condition. CONSTITUTION:A control section 5 decides whether or not noise check is to be implemented with a program stored in a ROM 2 when a line is connected based on the detection of a call signal or an input of a communication instruction from an operation section 9. In the case of implementing the noise check, the retransmission interval of an initial identification signal of a receiver side is used and a tonal signal detector 7 checks the state of a signal on line. That is, a frequency data of a frequency counter 75 and a signal energy detection signal of an integration device 76 are inputted to a control section 5 and when the two signals satisfy a prescribed condition, it is decided that a prescribed total procedure signal is received. When the control section 5 judges no effect on the communication, since the communication is continued, sure communication is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a data communication device, and particularly to a communication device that uses a tonal procedure signal in a communication control procedure and has means for detecting a significant tonal procedure signal.

[Prior Art] Traditionally, in facsimile communications, image transmission errors may occur due to background noise (white noise, impulse noise, etc.) during image transmission. When an image transmission error occurs on the receiving side, there is a known method of terminating the communication due to an error, thereby notifying the transmitting and receiving side translators of the occurrence of the error in a post-communication procedure. Alternatively, a method is also known in which error correction processing is used to attempt to transmit a correct image.

[Problems to be Solved by the Invention] However, although image transmission errors can be confirmed with the above-mentioned conventional technology, there is a large time loss due to retransmissions or fall packs, resulting in a significant increase in communication time and communication costs. There was a problem with it being bulky. This problem is not limited to facsimile devices, but is common to communication devices that use similar data transmission methods.

An object of the present invention is to solve the above problems.

[1,000 Steps to Solve the Problems J In order to solve the above problems, in the present invention, a tonal procedure signal is used in the communication control procedure, and in a communication device having a means for detecting a significant tonal procedure signal, the communication After the line is connected, and prior to data transmission, the detecting means detects a signal from the other station after connection, measures the expected influence of background noise on communication, and sets the communication conditions according to this measurement result. We searched for a configuration to control this.

[Function 1] According to the above configuration, the degree of influence of background noise on communication can be measured in advance after the communication line is connected, and communication control can be performed according to the measurement results, without providing any new measuring means. [Embodiment J] Hereinafter, the present invention will be explained in detail based on the embodiment shown in the drawings. Here, an actual example of a facsimile machine is shown.

Figure 1 shows the structure of a facsimile machine incorporating the present invention. In FIG. 1, reference numeral 5 denotes a control unit consisting of a microprocessor or the like. ROM2, RAM as work area
3 is connected to control the operation of the entire device according to the program stored in ROM2. The control unit 5 is connected to the following components. First, code 8 is a modem and NCU (network control unit)
, a communication unit consisting of an automatic call originating/terminating device, etc., and used as an interface between the device and the communication line 10. Image input/output is performed by a reading section 4 and a recording section 6.
The reading section 4 is. It consists of a CCD line sensor, a document transport system, etc., and is used to read document images. The recording section 6 is comprised of a thermal recording head, a recording paper conveyance system, and the like, and is used to record received images or images read by the reading section 4 during original copying.

The operation unit 9 is for a user interface,
It consists of a display and a keyboard including a numeric keypad and function keys. In figure l. A display, such as an LCD display, is independently designated by l. In the device shown in FIG. 1, a tonal signal detector 7 is provided. This tonal signal detector 7 is used to detect tonal procedure signals such as CHD signals, and has a configuration as shown in FIG. 2. As shown in FIG. 2, the tonal signal detector 7 includes a low-pass filter 71 and level adjusters 72 and 73 that manually input the received signal input from the communication section 8.
, a binarization circuit 74, a frequency counter 75 that processes the output of the binarization circuit 74, and a signal energy detector including an integration circuit 76. The signals at the connection points a-e in Fig. 2 are expressed as shown in Fig. 3 (A) to (
E) and (F) respectively.

The binarization circuit 74 outputs a binarized signal as shown in FIG. 3(B) by comparing the input signal shown in FIG. 3(A) with a threshold value th. (If the level of the human signal is smaller than the threshold th as shown in Fig. 3 (F), binarization cannot be performed.) The frequency counter 75 is set as shown in Fig. 3 (B).
sampling clock cJk faster than the binary signal of
The integrator 76 counts the frequency and outputs a digital value corresponding to the frequency of the received signal (Fig. 3 ()). On the other hand, the integrator 76 outputs an integral signal as shown in Fig. 3 (D). The signal energy detection signal SDT (the bar on the symbol indicates a negative logic The frequency data of the frequency counter 75 and the signal energy detection signal of the integrator 76 are input manually to the control section 5, and these two
If both signals satisfy a predetermined condition, it is determined that the expected tonal procedure signal is being received. That is, if a signal having a predetermined frequency and a signal energy greater than a preset value is received, it is determined that a significant procedure signal is being received. Next, the operation of the above configuration will be explained with reference to FIG. FIG. 4 shows the image transmission procedure of the control section 5 of FIG. 1. The illustrated procedure is for conventionally controlling communication according to the state of noise, and is stored in the ROM 2 as a program for the control unit 5. When the line is connected based on the detection of a call signal or the input of a communication command from the operation unit 9, itI fit
First, in step Sl, the unit 5 determines whether or not to perform a noise check related to the present invention. This judgment is made by
This is done by determining the state of the control parameters in the RAM 3 that are set according to the operations of the controller. If a noise check is not to be performed, communication continues as usual, but if a noise check is to be performed, step S2 is performed.
Perform the following processing.

In step S2, the initial identification signal (here, DI
Using the retransmission interval of S (digital identification signal), the tonal signal detector 7 checks the state of the signal on the line.

In step S3, the influence of noise on communication is determined from the measurement results obtained in step s2. Step S3
One possible method for determining the influence on communication is to determine the level of background noise during the retransmission interval of the initial identification signal of the other station and its distribution on the frequency axis. For example, in a certain measurement period, FIGS. 5(A) and (B)
When the intensity of the signal level is distributed as shown by curve C in FIG. The noise level can be evaluated by sequentially changing as shown in B) and determining at which level the identification signal of the partner station having the frequency fx can be detected. As is clear from FIG. 5, the detection level of the tonal signal detector 7, which can identify a significant signal having the frequency fX, increases or decreases depending on the intensity of the background noise. In other words, in the example of Fig. 5, Fig. 5 (
Although a significant procedure signal cannot be detected at the detection level B), if the detection level is increased to the detection level shown in FIG. 5(A), a procedure signal can be detected for the first time.

That is, since frequency components other than those around the frequency fx can be considered as noise components, the value of the detection level at which a significant signal can be detected increases as the noise level increases, and decreases as the noise level decreases.

Therefore, in the determination at step S3, the influence of communication on the S/N ratio or noise level can be determined based on the magnitude of the detection level at which the tonal signal detector 7 can detect a significant signal. This determination can be made by comparing the detection level at which a significant signal can be identified with a threshold value stored in a RAM or the like in advance. This threshold value is determined based on the dependence relationship between the error rate that does not cause an error termination due to a transmission error and the S/N ratio detected as the detection level of the above-mentioned tonal signal detector 7, which has been measured in advance through experiments. This threshold value can also be set by the user at the operation panel 9.
As a result of determining the impact on communication in step s3 as described above, if it is determined that there is no impact on communication, communication may be continued. , If it is determined that there is an impact, the process moves to step s4, and if the device is set to allow fall pack, the optimum communication speed is determined based on the data measured using the method described above. Select and continue communicating. Additionally, if the device is configured not to fallback or has already fallen back to the lowest communication speed, a repeated disconnect signal (D
CN signal, etc.) to open the line, or, in the case of a called call such as a polling transmission, the @ line is opened without answering in the expectation that there will be a dial.

Although the transmission procedure has been described above, it is also possible to perform similar control in the receiver, for example, using the retransmission interval of the other party's CS (digital command) signal. In this case, training and TCP (} training check) signals will be received following the DCS, so T
If the reception result of the CP signal is good, communication can be continued. In this case, the noise check control shown in FIG. 4 may or may not be performed. On the other hand, if the reception result of the TCP signal is defective, the TCP signal is
The reception result of the CP signal can also be made highly reliable in terms of its influence on communication. In the case of the receiving procedure, if a fallback is to be performed from the receiving side, the purpose can be achieved, for example, by once again declaring the result of speed adjustment to the DCS signal as the maximum speed using the DIS signal. If fallback is no longer possible, there is no need to declare it again, and it is sufficient to return the FTT signal.

In addition, as a common control for transceivers, if the noise level is determined to be high enough to affect communication and the line is disconnected or falls back as described above, an alarm sound,
The user may be warned of this through display or the like. Furthermore, after this warning, you can select whether or not to immediately disconnect the line or force communication without performing a fallback.
Alternatively, the user may be allowed to specify it via .

Although a facsimile machine has been exemplified above, it goes without saying that the present invention can be implemented in various communication devices that use similar communication procedures.

[Effect of the Invention 1] As is clear from the above, according to the present invention, in a communication device that uses a tonal procedure signal in a communication control procedure and has means for detecting a significant tonal procedure signal, data transmission is performed after a communication line is connected. Prior to this, after the connection, while detecting a predetermined signal of the other station by the detection means, measuring the predicted influence of background noise on communication,
Since we have adopted a configuration that controls communication conditions according to the measurement results, we can measure the influence of background noise on communication after the communication line is connected, without installing any new measurement means, and then respond according to the measurement results. control communication using
Retransmission due to error termination, which can improve the reliability of communication,
Error correction communication has excellent effects such as not causing substantial increases in communication time and communication costs.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a facsimile machine adopting the present invention, Fig. 2 is a block diagram showing the structure of the tonal detector shown in Fig. 1, and Figs. A waveform diagram showing the operation of the detector, FIG. 4 is a flowchart diagram showing the transmission procedure of the control unit in FIG. 1, and FIG.
B) is an explanatory diagram showing the noise level evaluation method.
■Display section 2--ROM 3--RAM 4--Reading section 5--Control section 6--Recording section 7--Tonal signal detector 8--Communication section 9-- 1 Operation part l O...Communication line Facsimile installation foo, 7th Figure 1 clk 11111111 11111111 1+ body (F)

Claims (1)

[Claims] 1) In a communication device that uses a tonal procedure signal in a communication control procedure and has means for detecting a significant tonal procedure signal, after a communication line is connected and prior to data transmission, the detecting means detects a predetermined signal of the other station after the communication line is connected. A data communication device characterized in that, while detecting background noise, the predicted degree of influence on communication is measured, and communication conditions are controlled according to the measurement result.