JPS6334669B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the activation of a terminal device that uses a general subscription telephone line for communications other than telephone calls. More specifically, when a pair of subscriber telephone lines is connected to a telephone and two other terminal devices for communication other than telephone calls, the communication of one terminal device may cause the activation operation of the other terminal device to erroneously occur. The present invention relates to a method for starting a terminal device that does not cause such problems.

[Conventional technology]

In recent years, automatic meter reading to check usage of water, gas, electricity, etc., or monitoring of various electric power equipment, etc.
Furthermore, as a method to easily collect small amounts of data scattered over a wide area, such as when surveying the usage of vending machines, by sequentially activating slave stations from the master station, we have developed ”) is the most promising and is attracting attention.

On the other hand, recently, public facsimile machines have become popular for home use as terminal devices, and are designed to automatically receive calls using special signals from special facsimile communication networks.

In other words, in Japan's standard system, 1800 Hz, 2030 Hz, 2300
A special single frequency signal such as Hz is assigned. Additionally, a single frequency signal of 1300Hz is used as the activation signal for public facsimile communications.
By using signals of different frequencies among these single frequency signals, it has become possible to distinguish the activation of two terminal devices connected to one telephone line.

[Problem that the invention seeks to solve]

However, when two terminal devices with automatic call receiving functions, such as automatic meter reading or public facsimile machines, are connected in parallel to a pair of telephone lines, the data transmission signal of one telephone device may cause the other telephone to receive a call. The device may be activated by mistake.

For example, if the only activation condition is for the switch to transmit a single-frequency signal as described above, one terminal device uses a frequency modulated (FS) signal for data communication of the other terminal device. Detecting a component of the single frequency signal in the spectrum may cause erroneous activation.

Furthermore, when performing data transmission using a telephone line as described above, it is no exaggeration to say that the terminal system determines the cost of the system. In order to reduce the cost of the terminal system, it is not a good idea to use commercial power as the operating power source, but it is desirable to use the central power source from the exchange.

It is an object of the present invention to provide a system in which, when two terminal devices that perform communication other than telephone communication that have an automatic call receiving function, such as an automatic meter reading or a public facsimile, are connected to a pair of telephone lines, each terminal device has an effect on the other terminal device. It is an object of the present invention to provide a startup method that allows correct startup operation without causing any adverse effects. Another object of the present invention is to provide an activation method that gives priority to telephone calls over other data transmissions and prevents malfunctions caused by telephone voices or the like.

[Means for solving problems]

In the present invention, two terminal devices are activated not only by a special single frequency signal assigned to each as a activation signal, but also by having different polarities of the DC loop current of the telephone line as a activation condition. This is to prevent communications from one terminal device from causing the other terminal device to erroneously start up.

That is, in the present invention, first and second terminal devices that communicate with a telephone using signals other than telephone signals are connected to a pair of subscriber telephone lines, and the first terminal device is connected to the subscriber telephone line. The second terminal device includes a first detection means for detecting an incoming first single frequency signal, and the second terminal device includes a second detection means for detecting a second single frequency signal arriving at the subscriber telephone line. In the terminal activation method, the first terminal device includes a third detection means for detecting that the polarity of the DC loop current of the subscriber telephone line has changed from the telephone standby state to the opposite polarity. and means for activating the first terminal device when the detection output of the first detection means and the detection output of the third detection means are sent out simultaneously, the second terminal device comprising: , a fourth detection means for detecting that the polarity of the DC loop current of the subscriber telephone line is the same polarity as the standby state of the telephone, a detection output of the second detection means and a detection output of the fourth detection means; The present invention is characterized by comprising means for activating the second terminal device when the detection outputs are simultaneously sent out.

Preferably, the first and second terminal devices each include a detection circuit for detecting off-hook of the telephone, and a circuit for inhibiting the operation of the means for activating the terminal device based on the detection output of the detection circuit.

In addition, when one of the terminal devices uses the local power supply supplied to the telephone line, it is preferable to set the activation condition of this terminal device to the polarity opposite to that of the normal telephone standby state.

[Effect]

A single frequency signal having a different frequency is assigned to each of the first terminal device and the second terminal device for activation, and the terminal device to be activated can be distinguished by distinguishing the frequencies. However, this single-frequency signal alone may cause false activation, so in addition to selecting a terminal using this single-frequency signal, we also made reversal of the polarity of the telephone line a selection condition. That is, when selecting and activating the first terminal device, the single frequency signal assigned to the first terminal device is sent out to the telephone line, and the direct current of the communication current of the telephone line is reversed. When the second terminal device is selected and activated, a signal of the single frequency assigned to the second terminal device is sent to the telephone line, and the polarity of the telephone line remains unchanged. In this way, in addition to the selection based on the difference in frequency of a single frequency, the polarity of the direct current is used as a selection condition, and each terminal device is activated when both selection conditions match, thereby preventing erroneous activation.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

The figure is a diagram showing the connections and block configuration of a terminal device according to an embodiment of the present invention.

In the figure, numeral 100 is a first terminal device, numeral 200 is a second terminal device, and numeral 300 is a telephone set, which are connected to one telephone line 111 and one telephone line.
12 in parallel. In this example, the first terminal device 100 is a terminal device for automatic meter reading,
The second terminal device 200 is a minifax device.

The first terminal device 100 includes a single frequency receiving circuit 107 as a first detection means for detecting a first single frequency signal (in this example, 2300 Hz for a no-ringing communication service) arriving at a subscriber telephone line, The second terminal device is equipped with a single frequency receiving circuit 207 as a second detection means for detecting a second single frequency signal (1300 Hz for minifax in this example) arriving at the subscriber telephone line. The first terminal device 100 also includes a diode 102 as a third detection means for detecting that the polarity of the DC loop current of the subscriber telephone line has changed from the telephone standby state to the opposite polarity.
and a power supply circuit 106. Further, the single frequency receiving circuit 107 is activated by the output current of the power supply circuit 106 as means for activating this terminal device when the detection output of the first detection means and the third detection output are sent out simultaneously. It is structured as follows.

The second terminal device 200 is equipped with a photo coupler 202 as a fourth detection means for detecting that the polarity of the DC loop current of the subscriber telephone line is the same as that in the standby state of the telephone. Also, this terminal device 2
00, the output of the single frequency receiving circuit 207 and AND circuit 22 into which the output of photo coupler 202 is input
0 and its output circuit.

In the terminal device 100, two diodes 1
02 is a diode that turns on when the polarity of the telephone lines 111, 112 becomes opposite to that during telephone standby. Reference numeral 103 denotes a coupling transformer for AC signals, and reference numeral 105 denotes a connection line 13 to the power supply circuit 106 taken out from the midpoint tap on the primary side of the transformer 103.
Capacitor inserted between 1,132, code 10
7 is a first frequency receiving circuit connected to the secondary side of the transformer. Reference numeral 109 denotes a transmission circuit, which includes a modulation/demodulation section for finally performing data communication, a data processing section, and an interface section with external equipment via a connection line 116.

Reference numeral 108 connects the transmission circuit 109 to the transformer 103
A switch circuit 110 coupled to the switch circuit 110 is an off-hook detection circuit for detecting that the terminal device 200 is in operation or the telephone 300 is in use, and turning off the switch circuit 108 via the connection line 114. Further, the connection line 113 is a line that controls the switch circuit 108 when the single frequency signal is received by the reception circuit 107, and the connection line 15 is a current supply line from the power supply circuit 106, and the terminals 121, 122.
is a connection terminal of the terminal device 200 or the telephone 300. This terminal device 100 has telephone lines 111,1
It uses the local power supply from No. 12 and is activated by a reverse polarity and single frequency signal (2300 Hz in this example). That is, telephone line 11
1,112 becomes reverse polarity, the power supply circuit 106 is activated and the entire circuit is activated, and furthermore, the reception circuit 107 detects a single frequency signal, closes the switch circuit 108, and activates the transmission circuit 109. and start it.

Next, in the terminal device 200, reference numeral 202
203 is an AC signal coupling transformer, and 205 is a transformer 20.
A DC blocking capacitor inserted on the primary side of 3.
207 is a single frequency receiving circuit connected to the secondary side of the transformer, 209 is a transmission circuit consisting of a modulation/demodulation section and a data processing section for final data communication, and 20 is a transmission circuit that connects the transmission circuit 209 to the transformer 203. 210 is an off-hook detection circuit for detecting that the telephone 300 is in use and turns off the switch circuit 208 via a connection line 214; 220 is the output of the photo coupler 202 and the single frequency receiving circuit 207; This is a gate circuit that takes the logical AND of and controls the switch circuit 208. Reference numeral 231 denotes a switch, which is controlled by the transmission circuit 209, and creates a DC termination using a resistor 232 in order to automatically respond to incoming calls.
In addition, the connection line 215 is a current supply line from the power supply circuit 206 that uses commercial power, and the terminals 221 and 222.
is a connection terminal of the telephone 300. This terminal device 200 operates using external commercial power,
Moreover, when a single frequency signal (1300 Hz in this example) is received with the same polarity as the standby state of the telephone 300, an automatic call activation operation is performed. In other words, the photo-coupler 20 indicates that the polarity is the same.
The receiving circuit 207 detects that the single frequency signal (1300 Hz) has been detected by the switch circuit 2, and the receiving circuit 207 detects that the single frequency signal (1300 Hz) has been received.
08 is closed and the transmission circuit 209 is activated.

Next, the operation of this embodiment device will be explained.

If we consider normal data communications, frequency modulation (FS) signaling is generally used.
This FS signal is a binary frequency modulation signal whose frequency is shifted by logic “1” or “0”,
The spectrum is determined by the shift ratio, that is, the ratio of the frequency shift between mark and space to the dot frequency. Here, the dot frequency is a frequency determined by the communication speed and the pattern component of logic "1" or "0". The details are described in detail in ``Data Transmission'' published by Latisse and translated by Shogo Amari.

Such a spectrum appears as various frequency components depending on the code being communicated, although the level may be large or small, and may include a single frequency that is the activation condition for the terminal device, in which case it may lead to incorrect activation of the terminal device. .

In the present invention, in order to prevent false activation due to the spectrum of the FS signal during data communication, the two terminal devices 100 and 200 are activated only on the condition that they receive the assigned single frequency signal as described above. Instead, the polarity of the telephone line is used as an activation condition, and the two activation devices are devised so that they activate when the polarity is different from each other. Therefore, when one activation device is activated, the other terminal device cannot be activated, and one terminal device will not be erroneously activated during data communication.

In the case of automatic meter reading, the above polarity conditions are created in a special trunk placed in the exchange of the central office that accommodates the terminal equipment, and in the case of public facsimile, in the switching network including the facsimile-dedicated network.

Further, each terminal device 100, 200 is equipped with an off-hook detection circuit 110, 210, and the detection circuit 110, 210 detects the off-hook state of the lines 114, 2.
14, the switch circuits 108, 208 can be opened. As a result, it is possible to stop the data communication of this terminal device by off-hooking the next high-priority terminal device or telephone, and to give priority to calls from these telephones, etc. over other data transmission. can. At the same time, each terminal device detects that the handset of the telephone is lifted and stops its operation, thereby preventing malfunctions caused by the voice of the telephone or the like.

〔Effect of the invention〕

As described above, according to the present invention, one of the two terminal devices is prevented from being erroneously activated while the other terminal device is communicating. Furthermore, by providing an off-hook detection circuit in each terminal device, it is possible to give priority to telephone calls over data communication of the terminal device, and
It is also possible to prevent erroneous activation of the terminal device due to voice from the telephone or the like.

[Brief explanation of drawings]

The figure is a connection and block diagram of a terminal device according to an embodiment of the present invention. 100,200...terminal device, 300...telephone, 107,207...single frequency receiving circuit, 10
8,208...Switch circuit, 109,209...
...Transmission circuit, 110, 210...Off-hook detection circuit.

Claims (1)

[Claims] 1. First and second terminal devices that communicate with a telephone using signals other than telephone signals are connected to a pair of subscriber telephone lines; The second terminal device includes a first detecting means for detecting a first single frequency signal arriving at the telephone line, and the second terminal device includes a first detecting means for detecting a first single frequency signal arriving at the subscriber telephone line. In the activation method of a terminal device equipped with the second detecting means, the first terminal device has a first terminal device that detects that the polarity of the DC loop current of the subscriber telephone line has changed from the telephone standby state to the opposite polarity. and means for activating the first terminal device when the detection output of the first detection means and the detection output of the third detection means are sent out simultaneously, The terminal device includes a fourth detection means for detecting that the polarity of the DC loop current of the subscriber telephone line is the same polarity as that of the telephone standby state, and a detection output of the second detection means and the fourth detection means. and means for activating the second terminal device when the detection outputs of the detection means are sent out at the same time. 2. The first and second terminal devices each include a detection circuit for detecting off-hook of the telephone, and the claims include a circuit that prohibits the operation of the means for activating the terminal device based on the detection output of the detection circuit. A method for starting a terminal device according to item 1 or 2.