JPS60204129A - Data line automatic switching system - Google Patents

Abstract

PURPOSE:To ensure the high reliability of an analog data transmission line through automatic line changeover by using analog data from a channel section of a carrier terminal equipment to supervise always a transmission line thereby making the maintenance and inspection effective. CONSTITUTION:A data modulator-demodulator 202 converts base band data 201 into a data signal 203 in a voice band and the result is fed to an automatic line changeover device 204. A band stop filter 205 of the device 204 eliminates the component of a pilot signal of the signal 203 and branches the result into two, which are combined with a pilot signal from a pilot signal generator 206 at each of combiners 208, 209 and the combined result is transmitted to existing and spare carrier lines 212, 213. The signal 203 and the pilot signal from the lines 212, 213 are received by existing and spare separators 217, 218 of the automatic line changeover device 216 and the result is fed to a changeover device 221 and BPF219, 220. The pilot signal extracted from the BPF219, 220 is supervised by pilot supervisory circuit 223, 224 and the output controls the switch 221 thereby improving the reliability of changeover.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention provides analog data (50 to 9600 bits/
s) Pertains to transmission systems, particularly to automatic data line switching systems.

<Prior art> In response to the demand for high reliability despite its small capacity, an automatic data line switching system has been adopted for analog data transmission systems that use carrier telephone lines from the viewpoint of system economy and high line reliability. It is often done.

FIG. 1 is a block diagram of an analog data transmission system having a conventional example of this data line automatic switching system. For convenience, FIG. 1 is for one-way communication (4t?). Although only the two-way transaction is shown, it is commonly used for two-way mail order.

The baseband data signal lO1 is the data modulator/demodulator 10
2 is converted into a voice band data signal 103.

This voice band data signal 103 then goes up to the branch 105 provided in the automatic line switching device 104 and is split into the same two signals. The working transport line 112 runs between 106 and 114.
transmitted through. The other signal is routed between the carrier terminal equipment 109 and 117 on the transmitting side and the receiving side via the preliminary carrier port +1!11.
3. Working and backup transport line 112,
The voice 'II7 intra-region data transmission code 103 transmitted through 113 is transmitted to a switching device 123 provided in an automatic line switching device 122. A failure in the carrier line is detected by the common parts 115 and 118 of the carrier terminal equipment 114 and 117, respectively, and the i! 17 Delivery gland disorder information 120,1
21, it is input to the switching control circuit 124. The switching control circuit 124 sends a switching command signal 12 to the switching device 123 based on the information 120 and 121 (in the transport direction)
Send 5. The switch 123 selects either the working or protection carrier line based on the switching command signal 125, and transmits the voice in-band data signal 126 to the data modulator/demodulator fji 127. The baseband data signal 128 is then reproduced by the data modulation/demodulation device 127.

In this way, in the conventional data line automatic switching system,
Line faults are detected in the common section of the carrier terminal equipment, and if a line fault is not detected in this common section and a fault occurs in the communication path section after the common section, a line fault will occur. The switching control circuit could not detect this, and the lines could not be automatically switched.

<Object of the Invention> Therefore, the object of the present invention is to provide an automatic data line switching system that improves the reliability of carrier data transmission lines by enabling automatic line switching even when a failure occurs in the communication path. Our goal is to provide the following.

<Structure of the Invention> The present invention is based on the bandwidth of a carrier telephone line (0.3 to 3.4
Generally, a band of (0.3 to 3.0 KHz) is sufficient for medium data (50 to 9600 bit/8) transmission (CCITT Recommendation M1020). KHz), and in accordance with the first rule of transmission, a signal is inserted into this vacant band, and on the receiving side, the line signal containing the signal is branched for each line. The circuit is automatically switched by separating the pilot signal from one signal to obtain line failure information, and switching the other branched signal based on the line failure information.

<Examples> Examples of the present invention will be described below with reference to the drawings. C explanation 1
'ru. Figure 2 shows data distribution according to an embodiment of the present invention)
FIG. 2 is a block diagram of an analog data transmission method having the i139υB method. For convenience, Fig. 2 shows only the communication structure for one side, but generally speaking, the communication structure for both sides (
Used in i-reconstruction.

The baseband data signal 201 is a data modulator/demodulator J
i202 converts it into an audio band data signal 203. (X) The automatic line switching device 204 detects the frequency component of the pilot signal from the voice band data signal 203 by the band rejection filter 205 for inserting the pilot signal into the voice band data signal 203. After being removed, the splitter 207 &d branches into the same two signals.The two branched signals are sent to the combiner 2
After being combined with the pilot signal (frequency fp) generated by the pilot signal generator 206 at 08 and 209, the carrier terminal equipment 2 on the transmitting side and the receiving side
The working transport line 212 consisting of 10°214, the transmitting side, and the receiving side 14. Fitting end station device 211, 21
Each of the signals is transmitted to a backup carrier line 213 consisting of 5.

The voice band data signals transmitted through the working and protection carrier lines 212 and 213 and Byron) (Ei') are separated by separators 217 .
218, the signal is branched into two signals and output. One branched signal is transmitted to the pilot switch 22u, and the other signal is sent to the pilot monitoring circuit 2 after the pilot signal is extracted through band pass filters 219 and 220.
23 and 224 respectively provide the working and backup transport lines 21.
2.213 failures are monitored. Pilot monitoring circuit 2
The transport line failure information detected by 23 and 224 is transferred to the switch 1f as transport line information 225 and 226, respectively.
It is internally input to the ilJ control circuit 227. This switching control circuit 2
27 is the transport direction i! 1ill'r?・Lightning information 225, 22
6, the switching destination command signal 228 is sent to the switching device 221 based on
Send out. The switch 221 selects either the current or backup carrier line 212 or 213 based on the switching destination command signal 228 and transmits it to the band rejection filter 222 . After the pilot signal is removed by the band-rejection filter 222, the voice in-band data signal is transmitted to the data modulator Iff 230. This data modulation/demodulation device 23
0, the baseband data signal 231 is reproduced.

In addition, the frequency 21p of pilot number 4 and 1 is 3 to 3.4 KH.
This is an appropriate frequency selected from within the z band.

<Advantageous Effects> According to the present invention, since the analog data transmission path including the communication path section of the carrier terminal equipment is constantly monitored, it is not only effective for maintenance, but also facilitates analog data transmission by automatic line switching. High reliability of the line is ensured.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an analog data transmission system having a conventional example of an automatic data line switching system, and FIG. 2 is a block diagram of an analog data transmission system having an automatic data line switching system according to an embodiment of the present invention. It is. 201... Baseband data code (transmission side) 202
...Data modulation/demodulation device (transmission side) 203...Audio band data signal (transmission side) 204...Automatic line switching device (transmission side) 205...Band rejection filter 206...Pilot code generation Unit 207... Branch 208... Coupler (working carrier line) 209... Coupler (backup carrier side M) 210... Carrier terminal device 4 (transmission side, working carrier line gland) 211. ... Carrier terminal equipment f (transmission (1!l, backup transport line) 212... Working transport line 213... Protection transport line 214... Carrier terminal equipment (receiving side, working 9 transmission lines n) 2
15... Carrier terminal equipment f? J+, (receiving side, backup transport line) 216... automatic line switching device (receiving' (f!l
) 217... Separator (currently used transport port 9) 218...
・Separator (preliminary transport line) 219...Band pass filter (current transport port a1) 2
20...Band pass filter (preliminary conveyance side) 221
...Switcher 222...Band rejection filter 223...Pilot monitoring circuit (current carrier line) 22
4...Pilot monitoring circuit (preliminary transport line) 225.
... Working carrier line failure information 226... Backup carrier line failure information 227... Switching control circuit 228... Switching command signal 229... Data signal within voice band (receiving side) 230...
・Data modulation/demodulation device・((Reception-11111) 231
...Baseband data signal (receiving (i side).

Claims (1)

[Claims] In an analog data transmission system using a carrier telephone line, the transmitting side inserts a pilot signal into an empty band not used for data transmission within the carrier band, and the receiving side transmits the 41 (IT) signal containing this pilot signal to each line. The pilot signal is separated from one of the branched signals to obtain line failure information, and the other branched signal is switched based on this line failure information to perform line switching. A patented data line self-4Iij switching system.