JPS6354832A - Switching device for digital analog common standby system - Google Patents

Abstract

PURPOSE:To decrease the locking time at the time of changeover from analog signal transmission into digital signal transmission by inputting a pattern signal to a digital modulator-demodulator at the transmission of an analog signal so as to always supervise the fault state of the modulator-demodulator. CONSTITUTION:Switches 5, 6, 9, 10 are switched in the position to supervise modulator/demodulator 7, 8. Thus, an output signal of a pattern generator 12 is selected by the switch 10 and inputted to the digital modulator 8. The output of the digital modulator 8 is selected by the switches 6 and 5 and inputted to the digital demodulator 7. The output of the digital demodulator 7 is selected by the switch 9 and inputted to a pattern detector 11. Thus, the characteristic of the digital demodulator 7, the digital modulator 8 is always supervised by the pattern detector 11.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a digital signal transmission system that has a modem and performs regenerative relay, and a through transmission or analog transmission at an intermediate relay station in a digital/analog common protection line. With regard to equipment that switches between an analog signal transmission system and an analog signal transmission system that has an amplitude limiter, etc. necessary for
The present invention relates to a digital/analog common standby system switching device that allows the status of an iJ device to be monitored.

[Prior Art] A conventional switching device of this type is as shown in FIG. That is, a switch 3 connected to the input terminal 1,
It has a switching device 4 connected to the output terminal 2, and these switching devices 3.4 provide functions necessary for through transmission or analog transmission 1, such as an analog signal transmission system having an amplitude limiter 13, and regeneration of digital signals. The configuration is such that a digital signal transmission system having a digital demodulator 7 and a digital modulator 8 that perform middle A is selected.

Therefore, in the conventional switch, only the through transmission or the amplitude limiter 13 etc. necessary for analog signals are selected during analog transmission, and the digital demodulator 7 and digital modulator 8 are selected and used during digital transmission. It was something.

[Problems to be Solved] In the conventional digital/analog common backup system switching device described above, it is not possible to detect a failure state of the digital demodulator 7 and digital modulator 8 that are not in use during analog signal transmission. , and.

When switching from analog signal to digital signal,
There is a drawback that it takes a long time for the demodulator 7 to become normal.

The present invention has been made in view of the above-mentioned problems, and it is possible to detect a failure state of a modulator/demodulator in an unused digital signal transmission system during analog signal transmission, and also to enable switching from an analog signal to a digital signal. An object of the present invention is to provide a switching bag for a common digital/analog standby system, which allows a demodulator to return to normal status in a short time when the situation occurs.

[Means for Solving Problems] In order to solve the above problems, the present invention provides a method for connecting a digital signal transmission system having a digital demodulator and a digital modulator to a digital signal transmission system having a digital demodulator and a digital modulator at an intermediate relay station in a digital/analog common protection line. , a configuration including a pattern generator, a switch that inputs the pattern signal from the generator to the digital demodulator and the digital modulator, and a pattern detector that inputs the output from the digital demodulator and the digital modulator. It's Toshide.

Thereby, the pattern generator and pattern detector for monitoring the status of the digital modulator/demodulator can be switched and used only when the digital signal transmission system is not used.

[Example] An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a first embodiment of the present invention. In the switching device of this first embodiment, input terminal 1
a switch 3 connected to the output terminal 2; a switch 4 connected to the output terminal 2;
Digital demodulator 7 and digital modulator 8 in the digital signal transmission system, and amplitude limiter 1 in the analog signal transmission system
3 is the same as the conventional one.

Switching device 5, 6, 9. input terminal 1, output terminal 2, and digital demodulator 7.to. A digital signal transmission circuit connecting the digital modulator 8, the digital demodulator 7, the digital modulator 8, and the pattern detector 11. Switching is performed with the monitoring circuit to which the pattern generator 12 is connected.

The switching devices 3 and 4 shown in FIG. 1 are in an analog signal transmission state. The analog signal now input from the input terminal 1 is input to the amplitude limiter 13 by the switch 3, and then output to the output terminal 2 by the switch 4.

On the other hand, the switching devices 5, 6, 9, and 10 are switched to a state where they monitor the variable tl[7°8. Therefore, the output signal of the pattern generator 12 is selected by the switch 10 and input to the digital modulator 8. Digital modulator 8
The output is selected by the switch 6 and further by the switch 5, and is input to the digital demodulator 7. The output of digital demodulator 7 is selected by switch 9 and input to pattern detector 11 . The pattern detector 11 constantly monitors the characteristics of the digital demodulator 7 and the digital modulator 8.

FIG. 2 shows a blowing block diagram of a second embodiment of the present invention. The switching device of this second embodiment is configured to monitor only the failure states of the digital demodulator 7 and the digital modulator 8. In this case, a fault detection circuit equivalent to a pattern detector for detecting faults is installed in the digital demodulator 7.
and is built into the digital modulator 8. Therefore, the switch 9 and the pattern detector 11 are excluded.

Note that the pattern signal is input to the digital demodulator 7,
If a regular digital signal is input by switching while the clock frequency is synchronized, the time required for normal operation will be the same as when the digital demodulator 7 is in an unattended state and the clock frequency is not synchronized. This is generally much faster than switching with .

[Effects of the Invention] As explained above, the present invention enables constant monitoring of the failure state of the modulator/demodulator by inputting a pattern signal to the digital modulator/demodulator during analog signal transmission, and also enables the transmission of digital signals from analog signal transmission. This has the effect of shortening the lead-in time when switching to transmission.

[Brief explanation of drawings]

Figures 1 and 2 relate to embodiments of the present invention; Figure 1 is a block diagram of the first embodiment, Figure 2 is a block diagram of the second embodiment, and Figure 3 is the block diagram of the conventional example. Show the diagram. 3.4, 5.6 + switch 7: Digital demodulator 8: Digital modulator 9, 10: Switch 11: Pattern detector 12: Pattern generator 13: Amplitude limiter

Claims (1)

[Claims] At an intermediate relay station in a digital/analog common protection line, a pattern generator is connected to a digital signal transmission system having a digital demodulator and a digital modulator via a switch, and a pattern signal from this generator is connected to the digital demodulator. 1. A switching device for a common digital/analog backup system, comprising a switch for inputting an input to a digital modulator, and a pattern detector for inputting outputs from a digital demodulator and a digital modulator.