JPH0276437A - Data transmitting equipment - Google Patents

Abstract

PURPOSE:To automatically set up a line level without using manual operation by setting a proper receiving level for a receiver in an attenuation level value setting receiving circuit. CONSTITUTION:When a transmitter 1 and a receiver 2 are connected to a transmission line 7, a test signal generating circuit 11 is driven prior to data transmission and a test signal 102 is sent to an attenuation level value setting transmitting circuit 13 through a receiving level detecting circuit 12 in the receiver 2. The circuit 13 compares the signal 102 with the previously set proper receiving level value, and when their difference is more than a fixed value, an attenuation level changing signal 103 is sent so as to correct the attenuation variable of an attenuation circuit 5. The signal 103 controls the circuit 5 through an attenuation level value setting receiving circuit 14 in the transmitter 1 to adjust the circuit 5 to the proper receiving level. Then, normal data communication is started. Thus, an always optimum receiving level can be obtained by previously setting up the proper receiving level in the circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data transmission device capable of setting a plurality of transmission levels for transmitting data through a voice line.

2. Description of the Related Art Conventionally, a data transmission device using a voice line usually has an attenuation circuit called a transmission level adjuster in order to transmit a signal at a level suitable for a receiving end prior to data transmission.

Problems to be Solved by the Invention To explain an example of a conventional method for setting the level reached at the receiving end using a transmission level adjuster (hereinafter abbreviated as attenuation circuit), after establishing a line, the transmitter sends a modulated signal to the receiver. Send. At the receiving end, a person measures the received level at the connection point where the transmission line and receiver are connected using a level measuring device.
Check whether it is at the specified level. At this time, if the reception level is outside the specified level, request the person on the transmitter side to reset the attenuation circuit, and confirm that the reception level reaches the specified value before data transmission. conduct.

Normally, these steps are used to adjust the reception level to the specified reception level.

However, with this setting method, when setting an appropriate attenuation circuit, a service person or the like must measure the reception level and manually switch the setting.
The drawback is that it takes time to start up the system.

Also, even if you set it up once, if you use a different line,
Since the characteristics of the data transmission paths are different, there is also a drawback that settings need to be reset each time.

The present invention has been made in view of the above-mentioned conventional situation,
Therefore, it is an object of the present invention to eliminate the above-mentioned drawbacks inherent in the conventional technology, to be able to perform line level measurement and switching settings without human intervention, and to quickly start up a system. The object of the present invention is to provide a new data transmission device that can perform the following functions.

Means for Solving the Problems In order to achieve the above object, a data transmission device according to the present invention includes a data modulation/demodulation device that transmits data through an audio line and is equipped with an attenuation circuit that can set a plurality of transmission levels. , the transmitter includes a test signal generation circuit that sends a signal to a transmission line via a modulation circuit, the attenuation circuit, and an attenuation level setting that sets and controls the attenuation circuit according to a command code received from the receiver via the transmission line. a receiving circuit, the receiver includes a receiving level detecting circuit that detects a signal level of the test signal generating circuit that arrives from the transmitter via the transmission path, and a receiving level detecting circuit that detects the signal level of the test signal generating circuit that arrives from the transmitter via the transmission path, and detecting the attenuation based on the output of the receiving level detecting circuit. The attenuation level value setting transmitting circuit transmits an instruction code for setting and controlling the circuit.

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, a signal 101 input to a data transmission input terminal 3 passes through a transmitter 1, a transmission path 7, and a receiver 2, and is output to a data transmission output terminal IO.

Referring to FIG. 1, the transmitter 1 includes a test signal generating circuit 11 that generates a spectrum such that the received level detecting circuit 12 of the receiver 2 can detect an accurate level within the audio band.
and signals 102 and 10 output from the generating circuit 11
a modulation circuit 4 that modulates the signal of 1;

It includes an attenuation circuit 5 that attenuates the modulated output signal to a constant level, and a coupling circuit 6 that sends the modulated signal from the attenuation circuit 5 to a transmission line 7. The transmitter 1 also includes an attenuation level value setting receiving circuit 14 that receives an attenuation level change signal 103 sent from the receiver 2 via the transmission line 7 through the coupling circuit 6 and controls the setting of the attenuation circuit 5. .

On the other hand, the receiver 2 includes a coupling circuit 8 that inputs the modulated signals 101 and 102 sent from the transmitter 1 via the transmission path 7, and demodulates the signal 101 output from the coupling circuit 8 to output data transmission. It also includes a demodulation circuit 9 that sends out data to a terminal IO. The receiver 2 also receives the 10 output from the coupling circuit 8.
2, and an attenuation level value setting transmission circuit 13 that generates a signal for setting and controlling the attenuation circuit 5 based on the output signal thereof.

Next, the operation of this embodiment will be explained.

When the transmitter 1 and receiver 2 are connected to the transmission path 7, the test signal generation circuit 11 operates before data transmission, and the test signal 102 is sent to the modulation circuit 4. The signal is sent to an attenuation level value setting transmission circuit 13 via an attenuation circuit 5, a coupling circuit 6, a transmission line 7, a coupling circuit 8, and a reception level detection circuit 12. At this time, the amount of attenuation of the attenuation circuit 5 is the minimum value.

The attenuation level value determination circuit 13 compares the test signal 102 with a preset appropriate reception level value,
If the difference is greater than a certain value, an attenuation level change signal 103 is sent out to correct the attenuation amount of the attenuation circuit 5, and the attenuation level change signal 103 is transmitted to the coupling circuit 8, the transmission line 7, the coupling circuit 6, and the attenuation level value setting receiving circuit 14. The attenuation circuit 5 is controlled through the , and adjusted to an appropriate reception level. After that, normal data communication begins.

Therefore, by setting the appropriate reception level of the receiver in the attenuation level value setting receiving circuit 13 in advance, the optimum reception level can always be obtained.

As described in detail, the present invention makes it possible to set and control the attenuation circuit of the transmitter from the receiver in order to ensure an appropriate reception level at the receiver and the receiver. , there is no need to measure the reception level as in the past, and switching and setting of the attenuation circuit can be performed without manual operation, which reduces personnel costs and contributes to quick system start-up, which has practical effects. is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a data transmission device according to the present invention. 100. transmitter, 200. receiver, 300. data transmission input terminal, 400. Modulation circuit, 50. . Attenuation circuit, 600. coupling circuit, 7. ,,transmission line,800
．． Coupling circuit, 901. demodulation circuit, 10. , .

Claims (1)

[Claims] In a data transmission device that transmits data through an audio line and is equipped with an attenuation circuit that can set a plurality of transmission levels, the transmitter includes a test signal generation circuit that sends a signal to the transmission line through the attenuation circuit via a modulation circuit. and an attenuation level setting receiving circuit that sets and controls the attenuation circuit according to a command code received from the receiver via the transmission path, and the receiver receives the test signal arriving from the transmitter via the transmission path. Data characterized by comprising a reception level detection circuit that detects the signal level of the generation circuit, and an attenuation level value setting transmission circuit that transmits an instruction code for setting and controlling the attenuation circuit based on the output of the reception level detection circuit. Transmission device.