JPH04290366A - Automatic setting system for modem signal transmission level - Google Patents

Abstract

PURPOSE:To automatically set a modem signal transmission level and to easily set a facsimile, a data terminal equipment, etc., by setting the modem transmis sion level based on the magnitude of the current detected by a current detection means. CONSTITUTION:A coil 10 separates line and powder source systems. The telephone line becomes a constant value capable of the loop closing of dc resistance. A coil 11 serially provided on the line generates magnetic field proportional to the magnitude of the current of telephone lines L1 and L2, and a hole element 1 generates voltage proportional to the current. The voltage produced by the hole element 1 is amplified by an amplifier 2 and conveyed through an A/D converter 3 to a control part 4. On the other hand, the control part 4 calculates the lines loss of the telephone line based on the voltage value obtained from the A/D converter 3 and controls an attenator 6 so as to make a modem signal transmission level P the prescribed value. Therefore, the modem signal transmission level can be set according to the magnitude of the current of the telephone line.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a facsimile terminal device that transmits image information etc. via a modem using a telephone network;
The present invention also relates to a modem of a data terminal device that transmits data in an online system, etc., and relates to an automatic modem signal transmission level setting method for automatically setting the signal transmission level of the modem.

0002

2. Description of the Related Art When a terminal device having a modem is connected to a telephone network, it is necessary to set the modem's signal output level to a predetermined value according to technical standards related to the telecommunications industry. For example, if the signal transmission level of the modem is P,
P=-15dBm+L...(1) (L is the line loss of the line).

[0003] In order to satisfy such standards, it is necessary to take the line loss L of the line into consideration when installing the terminal equipment. Conventionally, in order to set the signal transmission level of the modem by taking the line line loss L into consideration, the construction worker (construction supervisor) would check the line line loss L by making an inquiry to the telephone office to which the terminal equipment is connected. Based on the line loss L value of the line, determine the transmission level based on the above equation (1), operate the attenuator built in the modem signal transmission section, set the signal transmission level, and install the terminal device. Was.

0004

[Problems to be Solved by the Invention] Therefore, when a user purchases a terminal device, it is necessary to request a construction worker to install the terminal device, and the construction worker also needs to install the terminal device at the telephone station to which the terminal device is connected. It was necessary to inquire about line line loss.

Furthermore, since the attenuator for setting the modem signal transmission level is usually located inside the terminal device, it takes a lot of time to set it up.

[0006] An object of the present invention is to provide a facsimile terminal device,
An object of the present invention is to provide a modem signal transmission level automatic setting method which is equipped with a function of measuring line loss in a terminal device having a modem such as a data terminal device, and which can automatically set the modem signal transmission level.

[0007]

[Means for Solving the Problems] An object of the present invention is to provide a terminal device including a modem and housed in a telephone network, including a current detecting means for detecting the magnitude of current in a telephone line; and means for setting the transmission level of the modem based on the magnitude of the current generated.

[0008]

[Operation] The magnitude of the current flowing through the telephone line is detected by current detection means. When determining the magnitude of the current, the line resistance can be determined from the property that the magnitude of the current and the magnitude of the line resistance are inversely proportional. Furthermore, line loss can be determined by the magnitude of the current, since the communication loss increases in proportion to the magnitude of the line resistance. The modem transmission level is set based on this determined line loss. This allows the modem signal transmission level to be automatically set.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a modem according to the present invention. Note that this embodiment is a diagram showing a case where a Hall element is used as the element for detecting the current of the telephone line.

A modem installed in a facsimile, data terminal device, etc. closes the relay 13 and sends a selection signal to the telephone line by the network control unit 7, then detects a response signal from the other party and activates the relay 12. By doing so, the modulation/demodulation section 5
are connected to telephone lines L1 and L2.

The coil 10 is for separating the line system and the power supply system, and on the telephone line side, the DC resistance has a constant value that can close the loop. A coil 11 provided in series with this generates a magnetic field proportional to the magnitude of the current in the telephone line, and the Hall element 1 generates a voltage in proportion to the magnitude of this magnetic field. That is, the voltage generated by the Hall element 1 is proportional to the magnitude of the current in the telephone line.

The voltage generated by the Hall element 1 is applied to the amplifier 2.
is amplified by the controller 4 via the A/D converter 3.
is transmitted to.

On the other hand, in the control section 4, the A/D converter 3
The line loss of the telephone line is calculated based on the voltage value obtained from
The attenuator 6 is controlled to a predetermined value, such as dBm+L (1) (where L is the line loss of the line).

The amplifiers 8 and 9 are for impedance matching with the transformer 10, and maintain a constant amplification factor.

As described above, since the direct current resistance of the transformer 10 on the telephone line side is constant, the current in the telephone line depends on the line loss. Therefore, the modem signal transmission level can be set depending on the magnitude of the current in the telephone line.

In this embodiment, a Hall element is used as an example of a current detection element. However, this is a photoresistor or a device that detects a current in a telephone line by detecting a voltage induced on the telephone line side of the coil 10. However, it also allows you to set the modem signaling level.

[0018]

[Effects of the Invention] According to the present invention, since the modem signal transmission level can be automatically set, facsimiles, data terminal equipment, etc. can be easily installed without requiring a construction worker (construction supervisor). Can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a modem of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Hall element, 2, 8, and 9... Amplifier, 3... A/D converter, 4... Control part, 5... Modulation/demodulation part, 6... Attenuator, 7... Network control part, 10 and 11... Coil.

Claims (1)

[Claims] 1. A terminal device including a modem and accommodated in a telephone network, comprising: current detection means for detecting the magnitude of current in a telephone line; 1. A method for automatically setting a modem signal transmission level, comprising means for setting a transmission level.