JPH0294861A - Automatic recognition system for data transmitter - Google Patents

Abstract

PURPOSE:To use a line installation or modulator-demodulator section or the like in common to both the data transmission using error control and the data transmission not using error control by sending a carrier intermittently when the error control function is provided prior to the start of the data transmission. CONSTITUTION:When a line is connected after a call from the caller side and a carrier detection section 40 detects a carrier, a control section 10 sends a carrier in a frequency of for a time tON after a wait time of t2 to apply interruption transmission to stop the carrier transmission by a time tOFF. Thus, the possession of the error control function is informed to a called party. When the repetition is detected by a prescribed number of times, the control section 10 of the called party stops the carrier by a time t4 and the continuous transmission in which the carrier is sent by the time tON and the transmission is stopped by the time tOFF is implemented. Thus, the provision of the error control function by itself is informed to the caller side.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a data transmission device that performs both data transmission using error control and data transmission without error control, in which the data transmission device on the other side has an error control function. The present invention relates to an automatic recognition system for a data transmission device that automatically recognizes whether or not the data transmission device has the following data before transmitting data.

(Prior art) Conventionally, this type of data transmission device has
There is one disclosed in No.-128260. This device includes a transmitting means for transmitting an intermittent carrier before data transmission using error control, a detecting means for detecting the presence or absence of discontinuity in the received carrier, and a detection result of the detecting means. and control means for recognizing whether or not the other party's data transmission device has an error control function based on the error control function. That is, before the control means of the conventional device transmits data using error control, it controls the transmission means and transmits an intermittent carrier, thereby making the data transmission device on the other side recognize that it has an error control function. . In addition, this control means monitors the detection result of the detection means when receiving a carrier from the data transmission device of the other party, and when the detection result indicates that there is an intermittent carrier, the control means provides an error control function to the data transmission device of the other party. If the detection result shows continuous carriers without intermittent carriers, it is recognized that there is no error control function. Therefore, the conventional device automatically recognizes whether or not the other party's data transmission device has an error control function based on the presence or absence of carrier interruption.

(Problem to be Solved by the Invention) However, in the conventional device described above, when transmitting data using a wireless line such as a car phone, when the received input electric field falls below a certain value, the power level of noise generated by the wireless device increases rapidly. , carrier discontinuation becomes undetectable, and in order to improve this, a bandpass filter with steep characteristics is required, making the device expensive and technically difficult to realize.

The present invention is intended to solve these problems, and aims to provide an inexpensive and highly reliable automatic recognition system for data transmission devices.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a data transmission device that performs both data transmission using error control and data transmission without error control. A transmitting means for transmitting an intermittent carrier before transmission, a detecting means for detecting the presence or absence of an intermittent carrier in a received carrier, and a data transmission device on the other side having an error control function from data demodulated from the received carrier. a determining means for determining whether or not the data transmission device has an error control function; It is characterized in that it is equipped with a control means for recognition.

(Function) According to the present invention having the above configuration, the present invention functions as follows. The control means (for example, the control section described later) transmits an intermittent carrier using the transmission means (for example, the carrier control section described later) before performing data transmission using error control, thereby preventing the data transmission device of the other party from receiving an error. It works to make you recognize that you have a control function. Further, the control means monitors the detection result of the detection means (for example, a carrier detection unit described later) and the judgment result of the judgment means when receiving the carrier from the data transmission device of the other party, and determines that the detection result is that there is an intermittent carrier. And if the data demodulated from the received carrier indicates that the data has a specific pattern indicating that the data transmission device on the other side has an error control function, the data transmission device on the other side has an error control function. It works to recognize that the detection result indicates continuous carriers without intermittent carriers, and that it does not have an error control function if it does not have the above-mentioned specific pattern. In this way, it is recognized whether the data device on the other side has an error control function or not based on whether the carrier is interrupted or not and whether the data demodulated from the carrier has the above-mentioned specific pattern.

Therefore, the present invention can solve the above problems and provide an inexpensive and highly reliable automatic recognition method for data transmission devices.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram of main parts of a data transmission device showing an embodiment of the present invention. As shown in the figure, the data transmission device of this embodiment includes a control section lO1 demodulation section 20, a modulation section 30, a carrier detection section 40, a carrier control section 50, a reception filter 6
0a, and a line changeover switch 60b.

The control unit IO reads the output signal of the carrier detector 40 via the signal line 14, controls line switching to the line changeover switch 60b via the line switching control line 16, and controls the carrier control unit via the carrier control signal line 15. At the same time, data is transmitted and received via the reception data signal line 12 and the transmission data signal line 13. The demodulator 20 demodulates the analog modulated signal sent to the reception signal line 26 and outputs it as a digital signal to the reception data signal line 12.
Send to. The modulator 30 modulates the digital signal from the transmission data signal line 13 and sends it to the signal line 35 as an analog modulated signal. The carrier detection unit 4o is connected to the reception signal line 2
Detect the received signal level from 6, and if the received signal level is above a certain value, it will be "1", and if it is lower than the certain value, it will be "0".
” are sent to the signal line 14, respectively. Carrier control unit 5
0 turns on/off the carrier signal from the modulation section 30 in accordance with carrier control signals (digital signals) of rlJ and rOJ sent to the carrier control signal line 15 from the control section IO. The reception filter 60a removes line noise from the received signal to prevent false detection by the carrier detection section 40. The line changeover switch 60b is used to switch the line connection between the inside of the device and the telephone set using a line control signal from the control unit IO, and when 1 is connected to 2, 1' is changed to 2. ', and when 1 is connected to 3, it becomes 1
' acts to connect with 3'.

FIG. 2 is a time chart for explaining the automatic recognition procedure of the data transmission device. The transmitted and received signals are shown.

Next, the automatic recognition operation of this embodiment will be explained with reference to the time chart of FIG.

First, a case will be described in which both the data transmission device on the calling side and the data transmission device on the called side have an error control function.

When a call is made by the calling side and the line is connected, the control unit 10 on the called side sends a line switching control signal to the signal line 14 at time TO, thereby switching the line changeover switch 60b from the telephone to the line. After switching, it will take a certain period of time. After waiting for a while, the carrier control section 50 is turned on (carrier control signal "1") to send a carrier of frequency fa to the line as an answer tone. When this carrier is recognized via the line, the control unit 10 on the calling side at time T1
Switch the line from the telephone to the inside of the device using the line changeover switch 60b.
(There are various possible methods for recognizing this carrier, but these are omitted as they are not directly related to the present invention). As a result, the carrier signal from the called side that comes through the line is sent to the receiving signal line 26 through the line changeover switch 60b and the receiving filter 60a.
Furthermore, it enters the carrier detection section 40.

As a result, the carrier detection section 40 sends a signal "1" indicating that the carrier has been detected to the control section]0 through the signal line 14.
Send to. The control unit 10 controls the time 1. When it is recognized that carriers have been continuously detected for a period of time t2, a carrier of frequency fo is transmitted for a period of time tON after waiting for a period of time t2. By performing intermittent transmission in which only the FP stops transmitting carriers, it notifies the called party that it has an error control function. At this time, the carrier is interrupted by the control unit 10.
from the carrier control unit 5 through the carrier control signal line 15.
This is done by controlling 0. While repeating this process up to N times, it is detected whether or not the carrier from the called side is stopped.

On the other hand, the control unit 10 on the called side monitors the signal from the carrier detection unit 40 via the signal line 14, and detects the signal from the carrier detection unit 40 at time t. N.

Detect whether there is a repetition of Lortp. When this repetition is detected a certain number of times, the control unit 10 recognizes that the calling party has an error control function. After that, the control unit 10 controls the carrier control unit 50 to transmit the carrier that has been continuously transmitted up to the time t4.
then stop for a time t. Send N carriers and wait. By performing intermittent transmission in which only the PP stops transmitting carriers, it notifies the calling party that it also has error control.

When the control unit 10 on the calling side recognizes that the carrier has been stopped for time t3 based on the output signal of the carrier detection unit 40, it controls the carrier control unit 50 to stop the intermittent transmission of the carrier, and the called side The carrier detection unit 40 detects discontinuation of the carrier from the carrier. In addition, time L4 is time L
It is set longer than 3. Then, when carrier interruption from the called side is detected a certain number of times, the control unit 10 recognizes that the called side also has error control, and the carrier control unit 1O recognizes that the called side also has error control.
0 to continuously send out carriers. When the control unit IO of the called side detects continuous carriers from the calling side for a time L5 via the carrier detection unit 40, it recognizes that the calling side also has error control, and changes the carrier from intermittent transmission. Continuous transmission. At this point in time T2, the called party completes automatic recognition. On the other hand, on the calling side, automatic recognition is completed at time T3 when the control unit IO detects continuous carriers from the called side via the carrier detection unit 40 for a time t6.

The case where both the calling side and the called side have an error control function has been described above, but in this case, the carrier transmission time during intermittent transmission. , and carrier transmission stop time. Fl- is set to be shorter than the time for something without error control to recognize that a carrier has been detected and the time to recognize that a carrier has disappeared (which is specified by the Be1l standard and the CITT standard). Otherwise, if the other side does not have error control, it recognizes the carrier at the first N time, then recognizes the carrier has been disconnected at the PP time and abandons the line. This is because you end up doing it.

In addition, in recognizing carrier discontinuity, the time of discontinuity is not strictly monitored, or hysteresis is provided. This is because in a car telephone line, fading occurs due to multipath while the vehicle is running, and carriers may disappear, so detection of intermittent time is not guaranteed.

Next, if the calling side has an error control function and the called side does not have an error control function, the calling side performs carrier intermittent transmission up to N times, but still Since the outage is not recognized, the called party recognizes that it does not have error control capabilities. Furthermore, if the calling side does not have an error control function and the called side does have an error control function, the called side receives the carrier information from the calling side. By being directly detected for more than N hours, the calling party recognizes that it does not have an error function.

When the reception condition is good, it is possible to correctly recognize whether or not the other party's data transmission device has an error control function by performing the operations described above. However, as the reception condition worsens, the noise level increases and the reception filter 60a
If the line noise cannot be removed even if the line noise is removed, it becomes impossible for the carrier detection unit 40 to detect carrier discontinuity, and the above operation alone will cause errors even if the data transmission device on the other side has an error control function. It will be judged and recognized as having no control function.

Therefore, if it is determined that the other party's data transmission device has an error control function, the controller IO further monitors the received data sent from the demodulator 20 via the received data signal line 12, and A device whose received data does not have error control sends out certain patterns, such as some being a series of 1's and others alternating 1's and 0's. Determine whether such a signal is detected for a certain period of time. It is only when the other party's data transmission equipment simultaneously recognizes that it has received a signal with a specific pattern when the carrier is continuous and the other party's data transmission equipment does not have an error control function. Make decisions that have no error control capabilities. Further, even if it is recognized that the carriers are continuous, if the above-mentioned specific pattern cannot be received, it is determined that the continuity of the carriers is due to the noise level due to deterioration of the line condition. It then determines that error control is necessary under such severe conditions on the line, and recognizes that the data transmission device on the other end also has an error control function. By using such a recognition method, it is possible to correctly determine and recognize whether or not the data transmission device on the other end has an error control function even when the noise level is high in a wireless line or the like.

As described above, according to this embodiment, the following effects can be obtained.

(2) In a data transmission device that selectively performs both data transmission using error control and data transmission without error control, line equipment, modulation section 20, and demodulation section 30 (modulation/demodulation section) can be shared.

■Common modulation/demodulation units (Bell and CCI) commonly used
TT), there is no need to increase the required precision of the filter for carrier detection (separation).

(2) Since recognition is made based on the presence or absence of carrier interruption (that is, tone on/off), highly reliable recognition can be performed even on lines with poor data transmission conditions, such as car telephone lines.

(Effects of the Invention) As explained above, according to the present invention, before starting data transmission, if an error control function is provided, a carrier is transmitted intermittently, and depending on whether or not this carrier is interrupted, Since the data transmission device recognizes the presence or absence of an error control function, and the received data from the other party's data transmission device receives and recognizes a signal with a specific pattern indicating the presence or absence of an error control function, error control In addition to making it possible to share line equipment and modulation/demodulation parts for both data transmission using a carrier detection system and data transmission without error control, the filter for carrier detection can be implemented with a simple filter, and highly reliable recognition can be achieved. can be done.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a time chart showing the automatic recognition operation of this embodiment. IO...Control unit, 20...Demodulation unit, 30...Modulation unit, 40...Carrier detection unit, 50...Carrier control unit, 60a...Reception filter, 60b...Line switching switch.

Claims (1)

[Scope of Claims] A data transmission device that performs both data transmission using error control and data transmission without error control, comprising: transmitting means for transmitting an intermittent carrier before performing data transmission using error control; a detecting means for detecting the presence or absence of discontinuity in the received carrier; a determining means for determining whether the data transmission device on the other side has an error control function from data demodulated from the received carrier; and a transmitting means for the transmitting means. and control means for recognizing whether or not the other party's data transmission device has an error control function based on the detection result of the detection means and the judgment result of the judgment means. Automatic recognition method for data transmission equipment.