JPH03117056A - Modem with data signal speed selecting and switching function - Google Patents

Abstract

PURPOSE:To selectively input and output two signals to and from one pin and to simplify the signal transmission line by providing a switching circuit for switching whether a first signal for transferring fall-back information is inputted or a second signal for sending out the fall-back information is outputted. CONSTITUTION:A circuit quality deterioration detecting means 29, a switching circuit 25, and a switching circuit control means 26 for switching in advance this switching circuit 25 to an input side of a first signal, when the circuit quality is not deteriorated, and for switching the switching circuit 25 to an output side of a second signal, when the circuit quality deterioration detecting means 29 detects deterioration of the circuit quality, and when a first signal is received are provided on MODEMs 13A, 13B with a data signal speed selecting and switching function. In such a way, irrespective of a higher sank circuit or a lower rank circuit, when their quality is deteriorated, fall-back can always be executed, and it is possible to cope with deterioration of the quality of the circuit.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides fallback information for reducing the data signal speed of a modem in response to deterioration of the line quality of an upper line, for example, to a modem on a lower line side. The present invention relates to a modem with a data signal speed selection switching function used in a fall pack system to transmit the data signal speed of the modem on the lower line side to the same speed as the modem on the upper line side.

[Conventional technology]

The interface circuit that selects the data signal speed of the modem is connected to the DTE supply signal (hereinafter referred to as the SDS signal) that controls the data signal speed of the modem from the data introduction (end device (1) i'E) side, and the line quality. A DCE supply signal (hereinafter referred to as FBI
It's called a signal.

) has been recommended by the CCITT (International Telegraph and Telephone Consultative Committee). However, it is specified that both of these signals use the same pin (pin 23) in the same interface circuit.

Therefore, the modem side selects whether to use pin 23 for the SDS signal or the FBI signal, and uses a strap or the like to permanently use the selected pin.

[Problem to be solved by the invention]

In this way, in conventional modems, this one pin is connected to the SDS
It was designed to have a fixed setting whether to use it for signals or FBI signals.

FIG. 5a shows an example of a conventional communication system. In this communication system, four modems 13-1 are connected in tandem between the host 11 and the data terminal 12.
~13-4 are arranged. The first modem 13-1 connected to one end of the upper line 14 as a line located on the host 11 side detects quality deterioration of the upper line 14 and sends an FBI signal to the host 11. It is now possible to do so. The second terminal connected to the other end of the upper line 14
The modem 13-2 also detects the quality deterioration of the upper line 14,
An FBI signal can be sent to the third modem 13-3. A third modem 13-3 connected to one end of the lower line 15 as a line located on the data terminal 12 side.
is adapted to input an SDS signal that controls the data signal rate. The fourth terminal connected to the other end of the lower line 15
The modem 13-4 is capable of detecting deterioration in the quality of the lower line 15 and sending an FBI signal to the data terminal 12.

In the system shown in FIG. 5, when the quality of the upper line 14 deteriorates (marked with an X in the figure), the first modem 13-1 uses a FBI signals can be provided to host 11. In addition, the second modem 1, 13-2 outputs the FBI signal, and the third modem 13-3 inputs the SDS signal to the lower line 1.
5 to the fourth modem 13-4, and the fourth
modem 13-4 outputs the FBI signal to data terminal 1.
2, the data signal rate can be similarly reduced. In this way, both the FBI signal and the SDS signal function well against the line quality deterioration shown in the figure.

However, a problem occurs if the quality of the lower line 15 deteriorates as shown in FIG. That is, in this case, the fourth modem 13-4 can send an FBI signal to the data terminal 12 to reduce the data signal rate, but when looking at the third modem 13-3, it can send an SDS signal to the data terminal 12. It is not possible to transmit the fall pack information to the upper line 14 side only by As a result, the automatic line fall pack function of the modem 13 was not effectively used, and the communication system was brought down because it could not cope with line quality deterioration.

SUMMARY OF THE INVENTION An object of the present invention is to provide a modem with a data signal speed selection switching function that always enables fall pack when the quality of the upper line or lower line deteriorates.

[Means to solve the problem]

In the present invention, (i) a line quality deterioration detection means for detecting the presence or absence of line quality deterioration; and (ii) a first signal for manually transmitting fall pack information or a first signal for transmitting fall pack information. (iii) When the line quality is not degraded, this switching circuit is switched to the input side of the first signal, and the line quality deterioration detection means detects the line quality. A modem with a data signal speed selection switching function is provided with a switching circuit control means for switching the switching circuit to the output side of the second signal when deterioration of the signal is detected and when the first signal is received.

That is, in the present invention, the first signal (for example, SDS signal)
The modem with the data signal speed selection switching function is equipped with a switching circuit that switches the second signal (for example, the FBI signal) within the modem with the data signal speed selection switching function. This will no longer cause problems when selected.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples.

FIG. 1 shows a simplified form of a communication system using a modem with a data signal rate selection switching function according to an embodiment of the present invention. That is, in FIG. 1, for the sake of simplicity, a line 21 and modems 13A and 13B with a data signal speed selection switching function connected to the line 21 are arranged between the host 11 and the data terminal 12, respectively.

The first modem 13A connects its 23rd pin 24 to the switching circuit 2.
It is placed on the common contact side of 5. The first contact of the switching circuit 25 is connected to the SDS signal input side of the control circuit (CONT) 26, and the second contact is connected to the FB of this control circuit 26.
Connected to the I signal output side. The switching circuit 25 is composed of contacts of a relay circuit 28 connected to a control circuit 26. That is, when this relay circuit 28 is in a demagnetized state, the first contact and the common contact are connected as shown in the figure.
The SDS signal supplied from the host 11 is now input to the control circuit 26. Further, when the relay circuit 28 is energized, the second contact and the common contact are connected, and an FBI signal is sent from the control circuit 26 to the host 11. The control circuit 28 is connected to one end of the line 21 via a modulation/demodulation section 29.

On the other hand, the other end of this line 21 is connected to a control circuit 26 of another modem 13B with a data signal speed selection switching function via a modem section 29 thereof.

The configuration of the modem 13B with a data signal speed selection and switching function is the same as the modem 13A with a data signal speed selection and switching function described above, so a description thereof will be omitted.

The state shown in FIG. 1 is a standby state in which the quality of the line 21 is normal, and the modem 1 with both data signal speed selection switching functions
The relay circuits 28 of 3A and 13B are in a demagnetized state. At this time, both switching circuits 25 and 25 are set to input the SDS signal.

Now, assuming that the communication system shown in FIG. 5a is configured, the operation of the modem with the data signal speed selection switching function of this embodiment will be explained with reference to FIGS. 2 to 4.

FIG. 2 shows the operation when the line quality of both the upper line 14 and the lower line 15 are normal. During standby, each modem 13-1 to 13
-4 is in a state where an SDS signal is input. Figure 2 shows the SDS from host 11 (see Figure 1) in this state.
This shows a state in which a signal is supplied to the first modem 13-1.

In the first modem 13-1, this is modulated by a modem section 29 (see FIG. 1) and sent to the upper line 14. In the second modem 13-2, the modem section 29 demodulates this signal, and the first
The control circuit 26 shown in the figure excites the relay circuit 28,
Switch the contact to the FBI signal output side. This results in
The signal supplied from the host 11 side is sent to the third modem 13-
3, where it is modulated and sent out to the lower line 15. The fourth modem 13-4 demodulates the signal, and its control circuit 26 similarly excites the relay circuit 28 to switch the contact to the FBI signal output side.

In this way, the data terminal 1 not shown in FIG.
2. It becomes possible to transmit signals for (see FIG. 1).

FIG. 3 shows the operation of the modem with the data signal speed selection switching function when the line quality of the upper line has deteriorated. In this case, when the first modem 131 detects deterioration in the quality of the upper line 14 with its modulation/demodulation unit 29 (see FIG. 1), it excites the relay circuit 28 and switches to the FBI signal output side.

This allows the host 11 to receive fall pack information.

The second modem 13-2 also performs the same switching operation as the first modem 13-1, and the fall pack information is transmitted to the third modem 1.
3-3. The fall pack information sent out from the third modem 13-3 is transmitted to the fourth modem 13-4 via the lower line 15, and here the switching circuit 25 (first
(see figure) is switched and finally transmitted to the data terminal 12.

FIG. 4 shows the operation of the modem with data signal speed selection switching function when the line quality of the lower line has deteriorated. In this case, when the fourth modem 134 detects deterioration in the quality of the lower line 15 with its modulation/demodulation section 29, it excites the relay circuit 28 and switches to the output side of the 1-' BI signal. This allows the data terminal 12 to receive fall pack information.

0 The third modem 13-3 also performs the same switching operation as the fourth modem 13-4, and the fallback information is transferred to the second modem 1.
3-2. The fallback information sent from the second model l-13-2 is sent to the first model via the upper line 14.
is transmitted to the modem 13-1 of the switching circuit 25 (
The contact point (see FIG. 1) is switched and the information is finally transmitted to the host 11.

〔Effect of the invention〕

As described above, according to the present invention, a switching circuit is provided that switches between inputting the first signal for transmitting fallback information and outputting the second signal for transmitting the Surkaf Allpack information. 2 pins per pin.
It is possible to selectively output two signals, and the signal transmission path can be simplified. In addition, when modems with a data signal speed selection function are connected in tandem, the entire system can be set to the same speed to prevent quality deterioration in the upper line and lower line.
7) There is an effect that a fallback speed can be set.

[Brief explanation of drawings]

Figures 1 to 4 are for explaining one embodiment of the present invention, of which Figure 1 is a system configuration diagram showing the main parts of a system using a modem with a data signal speed selection switching function; Figure 2 is an explanatory diagram showing the normal operation of a system using a modem with data signal speed selection switching function, and Figure 3 shows quality deterioration in the upper line when using a modem with data signal speed selection switching function. Figure 4 is an explanatory diagram showing the operation when a modem with a data signal speed selection switching function is used and quality deterioration occurs in the lower line. Figure 5 is the system configuration. FIG. 2 is an explanatory diagram for explaining the state of a line failure in the prior art. 11...Host, 12...Data terminal, 13...Modem with data signal speed selection switching function, 14...Upper line, 15... ...Lower line, 25...Switching circuit, 26...Control circuit, 28...Relay circuit, 29...
・Modulation/demodulation section.

Claims (1)

[Claims] Line quality deterioration detection means for detecting the presence or absence of line quality deterioration; and a second signal for inputting a first signal for transmitting fallback information or for transmitting fallback information. There is a switching circuit that switches whether to output or not, and a switching circuit that switches between
when the line quality deterioration detecting means detects the deterioration of the line quality and the first signal is switched to the input side of the first signal.
1. A modem with a data signal speed selection switching function, comprising: switching circuit control means for switching the switching circuit to the output side of the second signal when receiving the second signal.