JPH01293031A - Digital transmission equipment - Google Patents

Abstract

PURPOSE:To make prevention of interference, monitoring of a transmission line, and notification of fault occurrence possible and, at the same time, to perform a test by dividing a wireless link section into plural parts and to test an interface device itself by providing the interface device. CONSTITUTION:When the switch of the control section 24 of the interface device 2 is operated, a communication/test signal designating either ordinary digital communication or a test, a master/slave signal designating a master (transmitting side) or slave (receiving side) about two radio terminal stations, and a loop back signal indicating the method of the test are selected at the control section 24. The control section 24 controls each section of the interface device 2 in accordance with the selected signals. Therefore, tests, location of a faulty position, maintenance, etc., can be made easier.

Description

[Detailed description of the invention] 〔table of contents〕 overview Industrial applications Conventional technology Problems that the invention aims to solve Means to solve problems action Example Effect of the invention 〔overview〕 Regarding digital transmission equipment that performs wireless digital communication.

The purpose is to facilitate testing, locating fault locations, maintenance, etc.

A transmitting/receiving device that transmits and receives digital signals to and from other transmitting/receiving devices by wireless transmission, and a multiplexing device connected to the transmitting/receiving device via a connection line.

a first wireless terminal station including an interface device inserted into the connection line between the transmitting/receiving device and the multiplexing device, and having the same configuration as the first wireless terminal station; and a second wireless terminal station connected by a transmitting/receiving device, and a terminal device connected to each of the first and second wireless terminal stations, and the two interface devices allow transmission between them. The road is configured to be divided into multiple sections.

[Industrial application field]

The present invention relates to a digital transmission device, and more particularly to a digital transmission device that performs wireless digital communication.

In a digital transmission device, information such as audio, images, data, etc. is digitized and multiplexed high-order group digital signals are sent to a transmission path. Transmission methods include a method of transmitting on a high-speed digital line via a subscriber line, and a method of transmitting wirelessly using microwaves or millimeter waves.

[Conventional technology]

FIG. 10 is an explanatory diagram of the prior art.

In Fig. 1θ, 50 is a DMIX (multiplexer);
1 is subscriber line terminal unit (DSU>, 52 is 6 Mbps
53 is a transmitter/receiver (MRIJ) that performs wireless two-way communication, 54 is an antenna, 55 is a wireless transmission path, and 57 is a (user network).
interface) is a connection line.

FIG. 1θ (A) shows a digital transmission device using a high-speed digital dedicated line 52. DMIX 50 sends out a 5 Mbps multiplexed digital signal.

The two subscriber line termination devices 51 receive a reference clock from a reference station (not shown) that is a clock source, establish synchronization, and perform transmission and reception.

This digital transmission device is generally used, but if there is a failure in the high-speed digital dedicated line 52, for example, transmission and reception become impossible. Further, even for short distances, the cost of intervening subscriber lines is high, so a digital transmission device using a wireless transmission path as shown in FIG. 10(B) was developed.

The two transmitter/receivers 53 perform transmission and reception via their respective antennas 54. According to this, the connection between DMIX50 is
By using two lines, Ru 53 and DSU 51, backup can be provided in the event of a failure, and a large-capacity private network can be constructed without using subscriber lines.

[Problem to be solved by the invention]

In the digital transmission device of FIG. 1O(B).

Due to its nature, the transmitting/receiving device 53 needs to be small. Therefore, the transmitting/receiving device 53 does not have active maintenance functions other than transmitting and receiving.

Therefore, a problem arises in that the section between the two multiplexers 50, that is, from one connection line 57 to the other connection line 57 (hereinafter referred to as a wireless link section), is regarded as one transmission path. there were.

Therefore, when performing tests such as measuring the bit error rate (bit error rate), the wireless link section is treated as one transmission path to be measured.1For example, it is not possible to know the bit error rate of only the connection line 57. Ta. Similarly, in the wireless link section.

It was not possible to locate the fault location.

Furthermore, due to this, maintenance had to be performed on the entire wireless link section.

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital transmission device that facilitates testing, locating fault locations, maintenance, and the like.

[Means to solve the problem]

FIG. 1 is a diagram illustrating the principle of the present invention and shows a digital transmission device according to the present invention.

In FIG. 1(A), 1 is a transmitting/receiving unit (MRU), 2
is an interface device having the configuration as shown in FIG.
is a data processing device, 71 is a telephone or facsimile machine, 72 is a TV conference system, 8 (81, 82) is a connection line (cable), 9 is a high-speed digital dedicated line, and 10 is a DSU.

As shown in FIG. 1(A), a transmitting/receiving device 1, a Zeinface device 2. Multiplexer 3. Antenna 4° connection lines (cables) 81 and 82 constitute one wireless terminal station. The two wireless terminal stations have 50G between the opposing antennas 4.
Connection is made by transmitting and receiving Ilz electromagnetic waves. It should be noted that each of the two wireless terminal stations is distinguished as a mask (transmission) side and a slave (reception) side, and is indicated by adding suffixes A and B to the reference numeral. The two wireless terminal stations can be both transmitting and receiving.

A plurality of data terminal devices 70 to 72 of different types (multimedia) are connected to the multiplexing device 3 of the wireless terminal station. It is not necessary that the same data terminal device be connected to the mask side and the slave side, and the data terminal device connected to the slave side wireless terminal station is not shown.

When two wireless terminal stations, each connected to a data terminal device, perform transmission and reception, the wireless link section is the section that includes the wireless transmission path 5, and specifically, the section from the connection line 81A to the connection line 81B. be.

The wireless link section is 6Mbps (or 1.
This is a section in which digital signals multiplexed (multiple conversion) at approximately 5 Mbps are transmitted.

The multiplexing device 3 includes data terminal devices 70, 71 and 72 (
and PBX 6), it constitutes the user interface part.

The multiplexing device 3 is connected to the interface device 2 (ie, the wireless link section) and to the high-speed digital private line 9 via the DSUIO. Multiplexer 3
for use by connecting to.

The interface device 2 receives a signal in the same format as the signal sent to the high-speed digital private line, that is, a signal conforming to the commonly used in-home interface of the private line for high-speed digital transmission. Therefore, the wireless link section (from 81A to 818) is provided in parallel with the high-speed digital dedicated line 9 between the multiplexers 3 (user interface portion), and is one transmission line that functions in the same way.

This wireless link section, which is regarded as one transmission path, is divided into a plurality of sections by the interface device 2. For this purpose, the interface device 2 connects the connection line 8 (81 and 82) through which the multiplexed digital signal is transmitted at each wireless terminal station, that is, the connection connecting the transmitting/receiving device l and the multiplexing device 3. It is provided (inserted) in the middle of the line 8.

FIG. 1(B) shows a schematic configuration of the interface device 2. As shown in FIG.

In FIG. 1(B), 20 is an interface section, 21
22 is a switching section, and 22 is a test pattern processing section.

23 is a monitoring section, 24 is a control section, and 25 is a clock section.

26 is a display section.

When the operator operates a switch on the control unit 24 of the interface device 2, the operator instructs the control unit 24 to perform either normal digital communication or testing (test and fault location location, the same applies hereinafter). communication/test signal,
A master/slave signal indicating that the two wireless terminal stations are masks (transmitting side) or slaves (receiving side) and a loopback signal indicating the test method are selected.

In response to this, the control unit 24 controls the interface device 2
Controls each part of.

If the interface device 2 is a mask and an external clock is available, the clock unit 25 takes in this and generates a reference clock from it. The reference clock is created based on the reference clock input to the mask side multiplexer. The slave-less WA terminal station extracts the clock component from the received signal and establishes synchronization. Further, the clock section 25 generates a timing signal necessary for the test and sends it to the interface section 20 during a test.

The interface unit 20 is used when the digital transmission device performs communication over a wireless link section.

In normal communication, the digital small signal to be transmitted is connected to the interface between the transmitting/receiving device 1 and the multiplexing device 3. The received digital signal is transmitted in the order of connection line 82 - terminal d - interface section 20 - terminal - connection line 81 (down line). Terminals a and C are an input terminal and an output terminal for the upstream line of the interface device 2 or the interface section 20, respectively. Terminals d and b are respectively connected to the interface device 2.
Alternatively, it is an input terminal and an output terminal for a down line of the interface section 20.

In addition, the interface unit 20 performs the following operations in order to perform the test.
It includes a switching section 21 that switches transmission paths, and a test pattern processing section 22 that performs test pattern insertion and extraction 1 determination.

The monitoring unit 23 monitors signals transmitted via the interface unit 20 during normal communication. That is, the code error rate of the signal is measured, and when the code error rate exceeds a certain value, an alarm signal is sent out.

In addition, during testing, the monitoring unit 23 generates a test signal (test pattern) and interfaces the interface unit 2 with the signal (test pattern).
Send to 0. Then, an alarm signal is sent out based on the test results.

The display section 26 provides necessary displays to the operator based on these alarm signals.

The display section 26 is on the mask side during normal communication.

Both slave sides display alarm information under their own monitoring. During testing, it can only be operated from the monitoring section on the mask side. The display section shows "Testing in progress" on the slave side, and is displayed intensively on the mask side.

During the test, the switching section 21
0 (that is, the interface device 2), the transmission paths are switched so that transmission paths for various tests are formed. This switching is performed according to three signals input to the control section 24, and is mainly based on the connection between terminals a and b or terminals C and d.

On the other hand, during a test, the test pattern processing section 22 sends out a test signal supplied from the monitoring section 23 to a transmission line for testing at a timing according to a timing signal supplied from the clock section 25. That is, a test pattern is inserted into the transmitted signal. The signal including this test pattern is returned to the test pattern processing section 22 again via the transmission path for testing. For this purpose, the transmission path for testing is the interface section 20.
A transmission loop is formed in which a signal transmitted from (interface device 2) returns to the transmission source.

The test pattern processing unit 22 extracts a test pattern from the returned signal including the test pattern, compares it with the original test pattern, makes a judgment on the result, and sends the monitoring unit 23 to test the pattern. The determination result as a result of is sent.

[Effect]

FIG. 2 is an explanatory diagram of the operation of the present invention.

A signal instructing a test and a signal indicating a mask are input to the interface device 2A.

In response to this, the following processing is performed in the interface device 2A, which is a mask, as shown in FIG.

The switching unit 21 opens terminals a and a', and b and b'.

That is, the connection line 81A (multiplexer 3A) and the interface section 20 are divided (separated). This makes it possible to test the interface unit 20 itself.

The monitoring section 23 generates a test pattern, and the clock section generates a timing signal. The test pattern processing unit 22 that receives these inserts the test pattern into a predetermined position of the signal to be transmitted according to the timing signal, and sends it to the interface unit 20 (interface device W2A) to which the test pattern processing unit 22 belongs. A signal including this test pattern is sent to the terminal d connected to the terminal a in the interface section 20.

On the other hand, a signal instructing the test method, that is, the formation of a loop-shaped transmission path for the test, is input to the interface device W2A.

Accordingly, as shown in FIG. 2(B), a transmission loop for testing is formed starting from the mask side interface device 2A (input terminal a of the up line).

When loop ■ is instructed, the switching unit 21 of the interface device 2A switches terminals a and a, b and terminals d and d.
and connect terminals C' and d. This results in
The interface section 20 of the interface device 2A on the mask side is separated from the connection lines 81A and 82A (downstream). In addition, the transmission loop ■ is connected to the terminal d-interface section 2.
0 (up line side) one terminal C' → terminal terminal E interface part (down line side), C and d are connected even in the above case, and it is transmitted to the interface device 2B that it is being tested. ing.

When loop (2) is instructed, the switching section 21 of the slave side interface device 2B disconnects the terminals C and C' and connects the terminals C and d. As a result, the interface section 2 of the interface device 2B, which is the slave side,
0, the connection line 82B and the up line are disconnected. In addition, the transmission loop ■ is connected to the terminal d of the interface section 20 on the mask side.
Starting from.

The folded portion is the connection line 82B (down line) - terminal d of the slave side interface section 20 -> terminal C - connection wA82A (up line), and the mask side interface section (test pattern processing section 22) ( (down line side). In the case of loop (2), the dd connection exists, and the data under test is transmitted to the interface device 2B, causing the "TEST" LED on the slave side to be lit.

When loop ◎ is specified, the switching unit 21 of the slave side interface device 2B disconnects the terminals a and d and connects the terminals d and b'. Due to this.

The interface unit 20 of the interface device 2B on the slave side is separated from the connection line 81B.

In addition, the transmission loop ◎ is the interface section 2 on the mask side.
It starts from the terminal d of 0, and the folded part is the slave side interface part 20 (down line side) - its terminal b' -
Similarly, the terminal d-slave side interface section 20 (
(up line side) - ends at the master side interface section 20 (down line side).

In any transmission loop, the signal containing the test pattern sent by the test pattern processing section 22 on the mask side to the terminal I on the mask side is transmitted to the interface section 20 on the mask side.
It is transmitted again to the downlink side. The test pattern processing section 22 on the mask side is.

A test pattern is extracted from the signal transmitted to the interface section 20 (down line side), and this and the monitoring section 23
The test pattern is compared with the test pattern (same as the original test pattern) supplied from

According to loop (2), the test was performed on (the interface unit 20 of) the interface device W2A which was the mask side. If loops (2) and (2) are used together, it becomes possible to test mainly the transmitting/receiving devices IA, IB and the antennas 4A, 4B (sections directly connected to the wireless transmission path 5 of the wireless link section). By using loops {circle over (2)} and loops (O) in combination, it becomes possible to test mainly (the interface unit 20 of) the interface device 2B, which is the slave side, only by instructions from the mask side.

Tests using loops ■ or ◎ can be performed independently. Also, using the interface device 12B as a mask,
From this, loops ■ and ◎ can be formed in the same way. Which of the interface devices W2A and 2B should be used as a mask and slave?

You can decide either way before the service starts.

Manual switching is also possible during maintenance.

The test result is notified from the test pattern processing section 22 to the monitoring section 23 on the mask side, and is displayed on the display section 26 accordingly.

Note that in the interface device 2B which is the slave side, the control section 24 or the monitoring section 23 and the clock section 2
5 are configured not to generate test patterns and timing signals, respectively.

As described above, by providing the 9 interface device 2, the wireless link section, which was conventionally treated as one transmission line, can be divided into multiple sections 9 and tests and fault locations can be performed for each section. As a result, maintenance only needs to be done for each of them. Additionally, testing and fault location location can be performed not only on the interface device 2 itself, but also from one (mask side) to the other (slave side) of two wireless terminal stations that share a wireless link section. can.

〔Example〕

(al) Description of an Embodiment As an embodiment of the present invention, the digital transmission apparatus shown in FIG. 1 will be described in detail.

The multiplexing device 3 serves as an interface with (the interface device 2 of) the multimedia multiplexing section. That is, the data processing device 70 is (a plurality of) computers, workstations, etc., which are connected to the multiplexing device 3.
directly or via a packet switch or optical data highway. The terminal device 71 connected to the multiplexing device 3 via the PBX 6 is a telephone, a facsimile machine, a workstation, a multimedia mail system, or the like. The TV conference system 72 is connected to the multiplexing device 3 via, for example, a high-efficiency video transmission device.

The multimedia terminal devices 70 to 72 of one user interface part having the above configuration are 9, for example, 1
located in various locations within one building.

In order to perform transmission and reception with terminal devices 70 to 72 similarly provided in other buildings, each is connected to a wireless terminal station (and high-speed digital private line 9).

The transmitting/receiving device 1 and the antenna 4 are integrally formed.

The antennas are made to face each other. The distance between the antennas is lkm (standard) to enable communication via a private network.

In this communication, the signal that the interface device 2 receives from the multiplexer 3 is the same as the signal destined for the high-speed digital private line 9. That is, the wireless link section conforms to a commonly used private line in-home interface, and can be connected to an existing multiplexer in terms of frame format.

In this communication, one of the two wireless terminal stations with the antennas 4 facing each other is the mask side, and the other is the slave side. This switching is determined by operating a switch provided in the interface device 2.

FIG. 3 is a specific configuration diagram of the interface device 2, and corresponds to FIG. 1(B).

In FIG. 3, 24' is a switch operation section corresponding to the control section 24, 27 is a power supply section, 28 is a clock generation synchronization section, and 29 is a timing generation section.

30 and 32 are extraction 1 judgment and insertion processing units (hereinafter simply referred to as processing units) for uplink signals and downlink signals, respectively, and 31 and 33 are multiplexing units.

The interface device 2 is operated by a switch of a switch operating section 24', and has a power supply section 27 to which power is supplied via a power cable. Clock generation synchronization section 2
8 and the timing generating section 29 correspond to the clock section 25.

The processing section 30.32 and the multiplexing section 31.33 are connected to the interface section 20.32. Switching section 21. This corresponds to the test pattern processing section 22.

In Fig. 3, the transmission path during normal communication is as follows.

It is done as follows.

A signal to be transmitted from the transmitting/receiving device 1 is transmitted along a connection line 81 (up line) - processing section 30 - multiplexing section 31 - connection line 82 (up line). The signal received by the transmitter/receiver 1 is transmitted through the connection line 82 (down line) - processing section 32 - multiplexing section 33
- It is transmitted like the connection line 81 (down line).

In this case, all the signals on the connection line 81 have the same frame format as the signals transmitted on the high-speed digital dedicated line 9 (hereinafter referred to as connection line frame). On the other hand, the signal on the connection line 82 has a frame format (hereinafter referred to as a radio frame) in which various signals are inserted into the connection line frame based on the connection line frame.

That is, signals according to radio frames are transmitted between the two interface devices 2 in the wireless link section.

During normal communication, the processing section 30 once disassembles the connection line frame, inserts (adds) various signals into the predetermined positions, and the multiplexing section 31 multiplexes the signals and sends them out as a radio frame. Further, the processing section 32 decomposes the radio frame, extracts (removes) various signals at predetermined positions, and the multiplexing section 33 multiplexes the signals and sends them out as a connection line frame.

Using various signals included in the connection line frame.

During normal communication, the monitoring unit 23 and processing units 30 and 32 perform various processes described below. Note that the frame will also be described later.

In the third test, the transmission loops (1) to (2) are made linear.

The transmission loop (2) is actually configured as follows: (monitoring section 23-) multiplexing section 33-processing section 30-multiplexing section 31-processing section 32 (-monitoring section 23). The folding portion of the transmission loop (2) within the slave side interface device 2 is actually configured as follows: connection line 82 (down line) - processing section 32 - multiplexing section 31 - connection line 82 (up line). At this time, the processing section 32
The input signal is sent to the multiplexer 31 as it is without any processing. The return portion of the transmission loop ◎ within the slave side interface device 2 is actually the connection line 82 (down line) - processing unit 32
- Multiplexing section 33 - Processing section 30 - Multiplexing section 31 - Connection line 8
2 (upstream vA).

During the test, the signal on the transmission loop ■ or O.

All have a frame format (hereinafter referred to as a test frame) in which a test signal is inserted into a connection line frame as a base. As described above, the insertion and extraction of test signals are performed by the processing units 30 and 32, respectively.

Two connection line frames are supplied, for example, from the timing generator 29.

Using the test signal included in the test frame.

During the test, the monitoring unit 23 performs the processing described below.

The clock supply method in this embodiment using the clock generation synchronization section 28 is performed as follows.

Since the wireless link section is a private network, a reference clock is generated in the section.

The reference clock is generated by the clock generation synchronization section 28 on the mask side, and the mask side operates based on this. On the other hand, the slave side extracts the clock component from the signal transmitted from the mask side and performs slave synchronization. Processing for this purpose is performed in the clock generation synchronization section 28 on the slave side.

In order to generate the reference clock, the clock generation synchronization section 28
Equipped with L L (phase 1 locked 1 loop) circuit.

Highly stable external clock (64Kb) when used as mask side
ps) and generates a reference clock of a predetermined frequency,
On the other hand, when it is set to the slave side, no external clock is taken in.

This PLL circuit is made to run freely at a fixed oscillation frequency (12,624 MHz) with a stability of about 50 ppm. Normally, the mask side is dependent on a more stable external clock using a PLL, but even if the tracking range is exceeded due to interruption of the external clock supply, for example, the PLL circuit runs free.

This allows communication in the wireless link section even if the external clock is interrupted. After the external clock returns.

Again, subject to this. In this way, PLL circuit tracking/
By performing self-propulsion, continuity of communication in the wireless link section can be improved.

Note that in this embodiment, 0 is not shown.

A reference clock of 64 Kpbs is supplied to the PBX 6 in a looped manner between the two interface devices.

Therefore, upon power-off of the interface device.

There is no interruption of clock supply to other devices.

In this embodiment, an external clock signal is supplied from the multiplexer N3, and in response to this, the reference clock is supplied to the interface device 2.
is generated and supplied to the wireless link section. Further, in this embodiment, the multiplexer 3 (the multiplexer 3A in the mask example) takes in the clock supplied via the high-speed digital dedicated line 9 and sends it out as an external synchronization clock.

FIG. 4 to FIG. 7 are diagrams showing the structure of the frame.

FIG. 4 shows the structure of a connection line frame. The connection line frame is a frame used for a user network interface, and is a frame H and D.

It consists of free and ST channels. The H channel is a main signal information channel and includes information such as audio, 1 image, and data. The D channel is a signaling channel and contains signaling information that takes into consideration the use of broadband switching equipment. Free channels are left blank. The ST channel is a service information channel and has 5 bits per frame.

Four frames (four multiframes) constitute one superframe.

In this embodiment, various processes are performed by inserting various signals into the ST channel of one superframe.

5 and 6 only illustrate the ST channel of the superframe.

In Figures 5 to 7.

CRV: Coded Ru1e Violation
n, signal for frame synchronization (coding rule violation);

S: 5tatus of Indication,
Line usage status display signal, “1” indicates in use, “O” indicates not in use.

DNR: DCE Not Ready, a signal that notifies both user terminals of a failure on the J4 side. In this system, it appears on connection lines 81A (down) and 81B (down).

U N R: Uncontrolled Not R
eady, a signal that informs the other user's terminal of a failure on one user terminal side; in this system, it is sent to the other party when there is a problem with the terminal device 3A or 3B or connection &1181A (upstream) or 81B (upstream) be done.

S U N D: 5end Alarm, user
When a signal from a network interface cannot be received normally into the network, an Alarm+ signal is issued from the network side to the user network interface side. In this system.

Connection lines 81A (down) and 81B (down) transmitted using

REC: Input disconnection or synchronization loss.

F: Frame Bit + multi-frame synchronization bit, a signal that instructs the start of frame synchronization detection when all FFFs are "1".

P: Parity Bft, bit that maintains even parity throughout one frame.

ID: Identification Bit,
This bit is used to prevent interference, and has 16 combinations of 4 bits.

■ or ◎: Signal for testing by transmission loop ■ or ◎.

■' to O': Signals of the above ■ to ■ returned after being transmitted on the transmission loop.

It is.

FIG. 5 shows frames during normal communication in this embodiment. According to this embodiment, various signals are inserted and extracted by the interface device 2 during normal communication.

As shown in No. 511J (A), super frame S
A signal in which the signals CRV and S are inserted at predetermined positions of T is transmitted from the multiplexer 3A on the upstream line of the connection cotton 81A on the mask side.

The two mask-side interface devices that have received the connection line frame create a wireless frame based on this. In the radio frame, the H and D channels remain in the connection line frame, while the ST channel is as shown in FIG. 5(B).

In other words, in order to monitor the quality of the transmission path, an even number (
or odd number) is the signal P with parity.

Inserted at the end of the frame. Also, 4 bits (4 bits) are added to the second frame (or fourth frame) of the super frame.
A signal ID (ID code) of (not limited to focus) is inserted. The 10 code is used to prevent crosstalk.

In addition to this, a 3-bit signal F is used to achieve frame synchronization.
(FFF=111> is inserted, and the insertion position of the signal CRV is changed to insert the signal P. Also, if a failure has occurred in the transmission up to this point, the signal UNR is inserted at a predetermined position. Ru.

The wireless frame configured as described above is transmitted from the mask side to the slave side via the wireless transmission path 5. and,
The slave side interface device 2B receives a signal with an ST channel as shown in FIG. 5(C). This signal is the same radio frame as the radio frame created by the mask side interface device 2A.

Processing based on the signal P is performed in the slave side interface device 2B. That is, the monitoring unit 23 always measures the bit error rate using the signal P during normal communication. If the error rate exceeds a predetermined value (IXIO-'), the slave side display section 26 is notified of the deterioration of the transmission path, and each time an error pulse is sent from the slave side to the external output terminal, Output. Thereby, the quality of the transmission path can be monitored and maintenance can be easily performed. Further, processing based on the signal ID is similarly performed. Interface section 2 of slave side interface device 2B
0 (or the processing unit 32) knows from the ID code whether or not it is the masked side of the communication. If the communication is from the mask side, which should not be communicated, no further communication is performed. This allows wireless terminal stations using the same frequency to
Prevents interference even when a large number of devices are concentrated in a small area.

Reduce the frequency of data leaking to other stations.

Next, the interface device 2B returns the received radio frame to a connected VtvA frame. At this time, the H and D channels are left as the radio frame, while the ST channel is changed as shown in FIG. 5(D). be done.

That is, the signal P and ID are removed by the extraction for the above processing, and the signal F used for frame synchronization is
is removed and signal CRV is inserted in its original position. Furthermore, if a failure occurs in the wireless link section, a signal DNR is inserted at a predetermined position.

In addition, when the signal UNR is inserted (“l” is set) due to a failure on the connection line 81A, the super frame S with the signal 5END inserted at a predetermined position as shown in FIG.
The T-format signal is sent back to multiplexer 3A.

Figure 7 shows the test (or maintenance) in this example.
Shows the frame of time. At test time.

According to this embodiment, test patterns and the like are inserted and extracted by the interface device 2.

During the test, the mask-side interface device 2A uses the frame structure shown in FIG. 4 as a test frame.
Assume that a PN pattern (a pattern in which "1" and "0" are repeated alternately) is inserted into the 11 channels, and the ST channel as shown in FIG. 7(A) is created. That is, when performing the test using the transmission loop ■ mentioned above,
Flag 1” in the first bit of the ST channel in the 4th frame
stand up. It may also be caused by other transmission loops ■ or ◎.

Similarly, a flag is set at the position shown in 1. The PN pattern is generated by a timing generator 29 on the mask side.

The test frame passes through one of the transmission loops ① to ② formed by the control unit 24 on the mask side and returns as an ST channel having the same configuration as shown in FIG. 7(B).

Regarding the returned test frame, processing based on the PN pattern is performed in the mask side interface device W2A. That is, the monitoring unit 23 measures the bit error rate for the PN pattern during testing. For this purpose, the original PN pattern and the returned PN pattern are bit-compared. Then, a predetermined value (2X 1O-6
) or more, the display section 26 on the mask side is notified that the transmission path has deteriorated. Also, each time a bit comparison error occurs, it is output from the output terminal in the form of a pulse. This allows for monitoring the quality of the transmission path,
Maintenance is easy.

Note that the monitoring unit 23 identifies whether the communication is 1 normal communication or a test, and sets a value (IXIO-' or 2XIO-
' or ) selectively. By setting strict values during testing, the quality of the transmission path can be made high, and reliability during normal communication can be improved.

FIG. 8 is a diagram simply showing a transmission system for various signals inserted into the above-mentioned ST channel. In the figure, the "○" mark is the sending point, and the "■" mark is the detection point.

The signal S is regardless of the presence or absence of a failure on the transmission path.

It is transmitted from multiplexer 3A to 3B.

A signal DNR is sent for a failure (signal interruption or frame synchronization loss) within the wireless link section. Signal DNR is transmitted to multiplexer 3B. Multiplexer 3A
In case of input interruption or synchronization failure, a signal REC is generated and transmitted as UNR to the other terminal. Further, the signal 5END is returned to the multiplexer 3A.

During the test, the flags at the positions shown in FIGS. 7(A) and 7(B) are sent out and returned together with the test pattern including the PN pattern.

Needless to say, a similar transmission system can be constructed by replacing the mask side and slave side.

Mountain) Description of other examples FIG. 9 is an explanatory diagram of another embodiment of the present invention.

Only the vicinity of the interface device is shown.

In FIG. 9, 34 is the main clock generator (MC
G), 35 is an external monitoring device (NSP).

If the digital transmission device according to the invention is intended for use only in a private network, the external clock to the clock section 25 is supplied from the main clock generator 34.

The external monitoring device 35 is provided to manage the quality of the transmission path over time. That is, the monitoring section 23.

During normal communication and/or testing, a pulse signal (for example, one pulse per error) is sent out according to the measured bit error rate. Interface device 2
has an independent output terminal for this purpose. The external monitoring device 35, for example a data processing device, stores the pulse signals over time. Thereby, the management of the transmission path can be ensured.

〔Effect of the invention〕

As explained above, according to the present invention, in a digital transmission device that performs wireless digital communication, by providing an interface device, it is possible to prevent interference during normal communication, monitor the transmission path, and notify the occurrence of a failure. At the same time, during testing, it is possible to divide the wireless link section into multiple sections and test the interface device itself, improving the reliability and continuity of communication by digital transmission devices, and making it easier to maintain them. can be facilitated.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle configuration of the present invention. FIG. 2 is an explanatory diagram of the operation of the present invention. FIG. 3 is a configuration diagram of the interface device. 4 to 7 are configuration diagrams of the frame. FIG. 8 is a diagram showing a transmission system for various signals. FIG. 9 is an explanatory diagram of another embodiment. FIG. 10 is an explanatory diagram of the prior art. 1 is a transmitting/receiving device, 2 is an interface device, 3 is a multiplexing device, 4 is an antenna, and 5 is a wireless transmission path. 6 is a PBX (private branch exchange), 70 is a data processing device,
71 is a telephone or facsimile device, 72 is a TV conference system, 8 (81, 82) is a connection line (cable),
9 is a high-speed digital dedicated line, 20 is an interface section,
21 is a switching section, 22 is a test pattern processing section, 23 is a monitoring section, and 24 is a control section. 25 is a clock section, and 26 is a display section.

Claims (1)

[Claims] A transmitting/receiving device (1) that transmits and receives digital signals by wireless transmission with another transmitting/receiving device (1); a connected multiplexing device (3); and an interface device (2) inserted into the connection line (81, 82) between the transmitting/receiving device (1) and the multiplexing device (3). a first wireless terminal station; a second wireless terminal station having the same configuration as the first wireless terminal station and connected thereto by a transmitting/receiving device (1); and the first and second wireless terminal stations. 1. A digital transmission device comprising a terminal device connected to each of the terminal stations, the two interface devices (2) dividing a transmission path between them into a plurality of sections.