JPH0316461A - Modulator and demodulator - Google Patents

Abstract

PURPOSE:To prevent succeeding illegal use by sending a stored equipment identi fication number when an equipment identification number transmission command is received through a communication line and writing a new equipment identifica tion number when the equipment identification number transmission command and a new equipment identification number arc received so as to rewrite the equipment identification number even when the equipment identification number is used illegally. CONSTITUTION:An ID write command and an ID readout command commanded in a frequency other than a data transmission carrier through a communication line connecting to a host computer are analyzed by a command analysis circuit 2 via a hybrid transformer 10 and a filter 3. In the case of the ID write com mand, the ID is written through a write line 12. On the other hand, in the case of the ID readout command, the content of a register 1 is read from a readout line 13 through the command of the 18 transmission circuit 4 through the read out command line 11, the data is sent in a frequency other than the transmission carrier and sent to the communication circuit 14 via a filter 5 and the hybrid transformer 10.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a modulation/demodulation device.

[Conventional technology]

Conventionally, modulation and demodulation methods for modem equipment have been specified by CCITT's v series recommendations (V.21, V.23, etc.), but regulations for adding a function to send a unique device identification number to the modulation and demodulation equipment have been introduced. has not been standardized in interdisciplinary institutions.

[Problem that the invention seeks to solve]

Conventional modem equipment simply modulates and demodulates data from a terminal, so when connecting to a host combinator via a general telephone exchange network to receive service, the host computer is the terminal to which the terminal is registered. The identification number and password of the terminal operator are used to determine whether the Therefore, even if someone else uses the operator's identification number and password from another terminal, connection to the host computer cannot be restricted.

[Means for solving problems]

The present invention includes a first means for storing a device identification number in a modem device that accommodates a communication line connected to a host computer and is connected to a communication terminal, and a first means for storing a device identification number, and a device identification number sending instruction command through the communication line. a second means for transmitting the device identification number stored in the first means upon receipt;
and third means for writing a new device identification number into the first means upon receiving a device identification number write instruction command and a new device identification number through the communication line.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

Referring to the diagram showing one embodiment of the present invention, 1 is a register for storing a device identification number (ID), and a communication line 14 (in this case, 2lg) is connected to a host computer.
ID write instruction command and ID that are instructed on a frequency other than the data transmission carrier through
The fi output instruction command passes through a hybrid transformer 10 and a filter 3, and is analyzed by a command analysis circuit 2. If it is an ID write instruction command, the ID is written into register 1 through write line l2. On the other hand, in the case of an ID read instruction command, the ID sending circuit 4
to read the contents of register 1 through read line 13,
Sending on a frequency other than the data transmission carrier, filter 5
and is sent to the communication line 14 via the hybrid transformer 10.

In normal data transmission, the received carrier from the communication line 14 is given to the terminal 20 as received data via the hybrid transformer 10, filter 6, and demodulator 7. Furthermore, a transmission carrier is generated from the transmission data from the terminal 20 by the modulator 8, and is sent to the communication line 14 via the filter 9 and the hybrid transformer 10.

The above-mentioned modem [15] is a standard CCITTV. It has an interface of 24 recommendations.

In the above embodiment, a two-wire communication line has been described, but the same can be applied to a 4-meter communication line by omitting the hybrid transformer.

In addition, by backing up the power supply for the resistor 1 with a battery or a capacitor, etc., even if the power to the modem is cut off, the register 1
can hold the contents of

〔Effect of the invention〕

As explained above, according to the present invention, the device identification number of the modem can be written (rewritten) and read out through the communication line, so even if the device identification number is misused, it will not be rewritten. This will prevent future unauthorized use. Furthermore, by reading the device identification number before connecting the host computer and the terminal, unauthorized intrusion from a general modulation/demodulation device that does not have this identification number can be prevented.

[Brief explanation of drawings]

The figure is a diagram showing an embodiment of the present invention. 1...Register, 2...Command analysis circuit, 4...ID sending circuit, l4...
Communication line, 15... modem, 20... river terminal.

Claims (1)

[Claims] In a modem device accommodating a communication line connected to a host computer and connected to a communication terminal, a first means for storing a device identification number; a second means for transmitting the device identification number stored in the first means; and upon receiving a device identification number write instruction command and a new device identification number through the communication line, transmitting the new device identification number and third means for writing to the means.