JP2003134229A - Digital subscriber line test system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital subscriber line test system which can be synchronized with the burst timing of ISDN communications with a simple configuration. SOLUTION: The digital subscriber line test system applying a measurement test to a line to be tested synchronously with ISDN communications is provided with; a digital subscriber line test device at a telephone station side that detects the burst timing from an output of an ISDN clock supply device and transmits a modulation signal resulting from modulating a signal of a digital subscriber line signal band via the line to be tested; and a digital subscriber line test device at a terminal side that demodulates the modulation signal received via the line to be tested, extracts the burst timing and synchronizes itself with the burst timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital subscriber line (hereinafter, simply referred to as DSL) test system, and has an especially simple structure.
The present invention relates to a digital subscriber line test system capable of synchronizing with a burst timing of N (Integrated Services Digital Network: integrated digital communication network: hereinafter simply referred to as ISDN) communication.

[0002]

2. Description of the Related Art In a conventional DSL test system, a DSL tester is installed on each of a telephone station side and a terminal (subscriber home) side, and DSL is transmitted and received between two DSL testers via a line under test. It is a test.

On the other hand, ISDN is a TCM (Time Compressor).
Multiplexing: Time division control transmission method: Also called ping-pong transmission method. ) Is used, and the use time is alternately switched between transmission and reception on a pair of copper wires to enable full-duplex bidirectional transmission.

However, ISD cannot be used on the line near the line under test.
When N communication is performed, the echo generated from the ISDN line at the above-mentioned switching timing (hereinafter referred to as burst timing) causes crosstalk noise or the like on the line under test, which causes a decrease in transmission efficiency. .

Therefore, in the DSL test system, it is important to perform a measurement test in synchronization with ISDN communication (burst timing) on the line under test, but the burst timing can be obtained only by the DSL tester on the telephone station side. Therefore, the DSL tester on the terminal side must synchronize with the burst timing by some method.

FIG. 4 is a block diagram showing an example of such a conventional DSL test system. 1 in FIG.
Is an exchange installed in a telephone office, 2 and 6 are demultiplexers for separating and synthesizing low-frequency telephone signals and high-frequency DSL signals, 3
Is an ISDN clock supply device for supplying an ISDN clock, 4 is a DSL tester installed at the central office side, 5 and 9
Is a standard time generator that generates standard time from standard signals such as standard radio waves and satellite radio waves, 7 is a telephone corresponding to a terminal installed in the subscriber's home, and 8 is a DSL installed in the terminal (subscriber home) side It is a tester.

Reference numeral 100 is a circuit under test, 101 is a standard signal, and 102 is a TCM, which is an AMI (Alternated Mark In) including data transmission / reception timing (burst timing).
version) clock signal.

The exchange 1 is connected to a telephone signal input / output terminal of the demultiplexer 2, and a DSL signal input / output terminal of the demultiplexer 2 is connected to a DS.
The L tester 4 is connected. Further, one end of the line under test 100 is connected to the line terminal of the duplexer 2, and the line under test 10
The line terminal of the duplexer 6 is connected to the other end of 0.

The AMI clock signal 102 which is the output of the ISDN clock supply device 3 is applied to the DSL tester 4, and the output of the standard time generator 5 is also connected to the DSL tester 4.

The telephone 7 is connected to the telephone signal input / output terminal of the demultiplexer 6, and the DSL signal input / output terminal of the demultiplexer 6 is connected to the DS.
The L tester 8 is connected. The output of the standard time generator 9 is connected to the DSL tester 8, and the standard signal 101 is applied to the standard time generators 5 and 9, respectively.

The operation of the conventional example shown in FIG. 4 will be described with reference to FIGS. 5 and 6. FIG. 5 is a block diagram showing the details of the DSL tester 4 installed on the telephone station side, and FIG. 6 is a block diagram showing the details of the DSL tester 8 installed on the terminal (subscriber home) side.

In FIG. 5, 4,102, DS01 and T
S01 is assigned with the same reference numeral as in FIG. 4, 10 is burst timing detection means, 11 is communication means, 12 is control means for controlling the DSL tester 4 as a whole and for controlling burst timing detection means 10 and communication means 11. Is.

The AMI clock signal 102 output from the ISDN clock supply device 3 is connected to the burst timing detecting means 10, and the input / output signal of the burst timing detecting means 10 is connected to the control means 12.

The DS of the duplexer 2 shown by "DS01" in FIG.
The DSL signal which is a signal from the L signal input / output terminal is connected to the communication means 11, and the input / output signal of the communication means 11 is connected to the control means 12. Further, the occurrence time indicated by “TS01” in FIG. 4 is connected to the control means 12.

On the other hand, in FIG. 6, 8, DS02 and TS
Reference numeral 02 designates the same reference numeral as in FIG. 4, 13 is burst timing synchronization means, 14 is communication means, 15 is control means for controlling the DSL tester 8 as a whole and for controlling burst timing synchronization means 13 and communication means 14. Is.

The input / output signal of the burst timing synchronization means 13 is connected to the control means 15, and the DSL signal which is a signal from the DSL signal input / output terminal of the demultiplexer 6 shown in "DS02" in FIG. The communication means 14 is connected, and the input / output signal of the communication means 14 is connected to the control means 15. Also, FIG.
The standard time indicated by medium "TS02" is connected to the control means 15.

In FIG. 4, standard time generators 5 and 9 generate a standard time from a standard signal 101 such as a standard radio wave or a satellite radio wave, and output the standard time to the DSL testers 4 and 8, respectively. As a result, the DSL testers 4 and 8 are brought into a state of being synchronized with the standard time.

Further, in FIG. 4, the DSL tester 4 detects the burst timing from the input AMI clock signal 102 and sets the standard time when the burst timing is detected as the generation time (numerical data).

Then, the DSL tester 4 transmits the obtained occurrence time (numerical data) as a DSL signal to the DSL tester 8 via the demultiplexer 2, the line under test 100 and the demultiplexer 6.

For example, in FIG. 5, the burst timing detection means 10 detects the burst timing from the AMI clock signal 102 and outputs it to the control means 12, and the control means 12 generates the standard time when the burst timing is detected as the generation time ( Numeric data).

Further, for example, the control means 12 in FIG.
Controls the communication means 11 to set the occurrence time (numerical data) to D
It is transmitted as an SL signal as indicated by "DS01" in FIG.

On the other hand, the DSL tester 8 which has received the transmission through the demultiplexer 2, the line under test 100 and the demultiplexer 6 performs a measurement test or the like in synchronization with the generation time (numerical data).

For example, the communication means 14 in FIG.
As indicated by medium "DS02", the DSL signal is received and the generation time (numerical data) is output to the control means 15. The control means 15 determines the time of occurrence (numerical data) and "TS0" in FIG.
The standard time shown in 2 "is used as the burst timing synchronization means 13
Then, the burst timing synchronization means 13 obtains the burst timing based on the generation time (numerical data) and the standard time, and the control means 15 performs the measurement test and the like in synchronization with the obtained burst timing.

As a result, the DSL tester 4 on the telephone station side and the DSL tester 8 on the terminal side are synchronized by the standard time obtained from the standard signal 101 such as the standard radio wave or the satellite radio wave, and the DSL tester on the telephone station side is synchronized. By transmitting the occurrence time of the burst timing obtained in 4 as a DSL signal to the DSL tester on the terminal side via the line under test or the like, the DSL tester 8 on the terminal side can also be synchronized with the burst timing. Become.

FIG. 7 is a block diagram showing another example of the conventional DSL test system. In FIG.
Reference numerals 2, 3, 6, 7, 100 and 102 are the same as those in FIG. 4, 16 is a DSL tester installed on the central office side, and 17 is a DSL installed on the terminal (subscriber home) side. The tester 103 is a synchronization signal.

The exchange 1 is connected to a telephone signal input / output terminal of the demultiplexer 2, and a DSL signal input / output terminal of the demultiplexer 2 is connected to a DS.
The L tester 16 is connected. Further, one end of the line under test 100 is connected to the line terminal of the duplexer 2 and the line under test 1
The other end of 00 is connected to the line terminal of the duplexer 6.

An AMI clock signal 102, which is an output of the ISDN clock supply device 3, is applied to the DSL tester 16.

The telephone 7 is connected to the telephone signal input / output terminal of the demultiplexer 6, and the DSL signal input / output terminal of the demultiplexer 6 has a DS.
The L tester 17 is connected. Further, the synchronization signal 103 is directly connected from the DSL tester 16 to the DSL tester 17.

The operation of the conventional example shown in FIG. 7 will be described with reference to FIGS. 8 and 9. 8 is a block diagram showing the details of the DSL tester 16 installed on the telephone station side, and FIG. 9 is a block diagram showing the details of the DSL tester 17 installed on the terminal (subscriber home) side.

In FIG. 8, 16, 102, 103 and D
Reference numeral S11 is the same as that in FIG. 7, 18 is a burst timing detection means, 19 is a communication means, 20 is a control means for controlling the DSL tester 16 and the burst timing detection means 18 and the communication means 19. Is.

The AMI clock signal 102 output from the ISDN clock supply device 3 is connected to the burst timing detecting means 18, and the input / output signal of the burst timing detecting means 18 is connected to the control means 20. Further, the burst timing detection means 18 outputs the synchronization signal 103.

DS of the demultiplexer 2 shown by "DS11" in FIG.
The DSL signal which is a signal from the L signal input / output terminal is connected to the communication means 19, and the input / output signal of the communication means 19 is connected to the control means 20.

On the other hand, in FIG. 9, 17, 103 and DS
Reference numeral 12 is given the same reference numeral as in FIG. 7, reference numeral 21 is burst timing synchronization means, 22 is communication means, and 23 is control means for controlling the DSL tester 17 as a whole and for controlling burst timing synchronization means 21 and communication means 22. Is.

The input / output signal of the burst timing synchronization means 21 is connected to the control means 23, and the synchronization signal 103 is connected to the burst timing synchronization means 21.

Further, the demultiplexer 6 shown in "DS12" in FIG.
The DSL signal which is a signal from the DSL signal input / output terminal of is connected to the communication means 22, and the input / output signal of the communication means 22 is connected to the control means 23.

In FIG. 7, the DSL tester 16 detects the burst timing from the input AMI clock signal 102. Then, the DSL tester 16 uses the obtained burst timing as the synchronization signal 103.
Send to 7 directly.

For example, in FIG. 8, the burst timing detecting means 18 detects the burst timing from the AMI clock signal 102, outputs it to the control means 20, and outputs it as the synchronizing signal 103.

On the other hand, the DSL tester 17 that has received the synchronization signal 103 performs a measurement test or the like in synchronization with the synchronization signal 103.

For example, in FIG. 9, the burst timing synchronization means 21 obtains 103 and outputs it to the control means 23, and the control means 23 synchronizes with the synchronization signal 103 to perform a measurement test or the like.

As a result, the burst timing obtained by the DSL tester 16 on the telephone station side is directly transmitted to the DSL tester 17 on the terminal side as the synchronization signal 103, so that the DSL tester 17 on the terminal side also changes the burst timing. It becomes possible to synchronize.

[0041]

However, in the conventional DSL test system shown in FIG. 4, since the standard signal 101 such as the standard radio wave or the satellite radio wave is used, the two DSL testers are synchronized. Since an antenna and a receiving means for receiving standard radio waves, satellite radio waves, and the like are required, there is a problem that the configuration becomes large and the DSL tester becomes large.

For this reason, for example, if the size of the maintenance DSL tester is limited, it becomes difficult to mount the antenna and the receiving means.

The conventional DSL test system shown in FIG. 7 requires a dedicated communication line or the like for transmitting the synchronization signal 103 directly to the DSL tester 17 installed on the terminal (subscriber home) side. There was a problem saying that it would end up.

Therefore, for example, the terminal (subscriber home) side where only the line under test 100 is laid cannot be used. Therefore, the problem to be solved by the present invention is to realize a digital subscriber line test system capable of synchronizing with the burst timing of ISDN communication with a simple configuration.

[0045]

In order to achieve the above object, the invention according to claim 1 of the present invention is a digital subscriber line for performing a measurement test in synchronization with ISDN communication on a line under test. In a test system, a digital subscriber line tester on the telephone station side for detecting a burst timing from an output of an ISDN clock supply device and transmitting a modulated signal modulated into a signal in a digital subscriber line signal band through the line under test. , A digital subscriber line tester on the terminal side that demodulates the modulated signal received via the line under test to extract the burst timing and synchronizes the burst of ISDN communication with a simple configuration. It becomes possible to synchronize with the timing.

According to a second aspect of the present invention, in the digital subscriber line test system according to the first aspect,
The digital subscriber line tester on the central office side
Burst timing detection means for detecting the burst timing from the output of the SDN clock supply device, modulation means for modulating the burst timing into a signal in the digital subscriber line signal band, and output of this modulation means via the line under test. A burst of ISDN communication with a simple structure is constituted by the communication means for transmitting the data and the control means for controlling the entire digital subscriber line tester on the telephone station side and operating in synchronization with the burst timing. It becomes possible to synchronize with the timing.

According to a third aspect of the invention, in the digital subscriber line test system according to the first aspect of the invention,
From the burst timing, the digital subscriber line tester on the terminal side receives communication means for receiving the modulated signal via the line under test, demodulation means for demodulating the modulated signal and extracting the burst timing. The ISDN has a simple structure because it comprises a burst timing synchronization means for generating a synchronization signal and a control means for controlling the entire digital subscriber line tester on the terminal side and operating in synchronization with the synchronization signal. It becomes possible to synchronize with the burst timing of communication.

According to a fourth aspect of the invention, in the digital subscriber line test system according to the third aspect of the invention,
The burst timing synchronization means corrects the delay of the burst timing based on the delay information of the propagation path, whereby the delay error can be eliminated.

According to a fifth aspect of the present invention, in the digital subscriber line test system according to the third aspect,
The control means corrects the delay of the synchronization signal based on the delay information of the propagation path, whereby the delay error can be eliminated.

According to a sixth aspect of the present invention, in the digital subscriber line test system according to the fourth or fifth aspect of the invention, the delay information of the propagation path is stored in the digital subscriber line tester on the terminal side. By setting in advance, delay error can be eliminated.

According to a seventh aspect of the present invention, in the digital subscriber line test system according to the fourth or fifth aspect of the invention, the delay information of the propagation path is the digital subscriber line tester on the telephone station side. Is set in advance, is modulated into a signal in the DSL signal band together with the burst timing, and is transmitted to the digital subscriber line tester on the terminal side via the line under test, whereby the delay error can be eliminated. Further, the DSL tester on the terminal side can be easily miniaturized, and the delay information can be centrally managed by the DSL tester on the telephone station side, so that the delay information can be easily maintained.

[0052]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of a DSL test system according to the present invention. 1,
Reference numerals 2, 3, 6, 7, 100 and 102 are the same as those in FIG. 7, 24 is a DSL tester installed on the central office side, and 25 is a DSL installed on the terminal (subscriber home) side. It is a tester.

The exchange 1 is connected to the telephone signal input / output terminal of the demultiplexer 2 and the DSL signal input / output terminal of the demultiplexer 2 is connected to the DS signal.
The L tester 24 is connected. Further, one end of the line under test 100 is connected to the line terminal of the duplexer 2 and the line under test 1
The other end of 00 is connected to the line terminal of the duplexer 6.

An AMI clock signal 102 which is an output of the ISDN clock supply device 3 is applied to the DSL tester 24.

The telephone 7 is connected to the telephone signal input / output terminal of the demultiplexer 6, and the DSL tester 25 is connected to the DSL signal input / output terminal of the demultiplexer 6.

The operation of the embodiment shown in FIG. 1 will be described with reference to FIGS. 2 and 3. FIG. 2 is a block diagram showing the details of the DSL tester 24 installed on the telephone station side, and FIG. 3 is a block diagram showing the details of the DSL tester 25 installed on the terminal (subscriber home) side.

In FIG. 2, reference numerals 24, 102 and DS21 are the same as those in FIG. 1, 26 is a burst timing detection means, 27 is a modulation means, 28 is a communication means, and 29 is the entire DSL tester 24. It is also a control means for controlling the burst timing detection means 26, the modulation means 27 and the communication means 28.

The AMI clock signal 102 output from the ISDN clock supply device 3 is connected to the burst timing detecting means 26, and the input / output signal of the burst timing detecting means 26 is connected to the control means 29. Further, the output signal from the burst timing detection means 18 is the modulation means 2
Connected to 7.

DS of the demultiplexer 2 shown by "DS21" in FIG.
The DSL signal which is a signal from the L signal input / output terminal is connected to the communication means 28, and the input / output signal of the communication means 28 is connected to the control means 29.

The modulation signal of the modulation means 27 is connected to the communication means 28, and the control signal of the control means 29 is the modulation means 2.
Connected to 7.

On the other hand, in FIG. 3, reference numerals 25 and DS22 are the same as those in FIG. 1, 30 is burst timing synchronizing means, 31 is demodulating means, 32 is communicating means, and 33 is D.
It is a control means for controlling the entire SL tester 25 and controlling the burst timing synchronization means 30, the demodulation means 31, and the communication means 32.

The input / output signal of the burst timing synchronization means 30 is connected to the control means 33, and the demodulation signal of the demodulation means 31 is connected to the burst timing synchronization means 30.

Further, the demultiplexer 6 shown in "DS22" in FIG.
The DSL signal which is a signal from the DSL signal input / output terminal of is connected to the communication means 32, and the input / output signal of the communication means 32 is connected to the control means 23.

The output of the communication means 32 is the demodulation means 31.
, And the control signal of the control means 33 is connected to the demodulation means 31.

In FIG. 1, the DSL tester 24 detects the burst timing from the input AMI clock signal 102. Then, the DSL tester 24 modulates the obtained burst timing into a signal in the DSL signal band,
As the L signal, the duplexer 2, the line under test 100, and the duplexer 6
To the DSL tester 25 via.

For example, in FIG. 2, the burst timing detection means 26 detects the burst timing from the AMI clock signal 102 and outputs it to the control means 29 and the modulation means 27.

Then, for example, the modulation means 27 modulates the input burst timing into a signal in the DSL signal band and outputs it to the communication means 28 as a modulation signal. The communication means 28 transmits the modulated signal as a DSL signal to the DSL tester 25 via the demultiplexer 2, the line under test 100, and the demultiplexer 6.

On the other hand, the DSL tester 25 which has received the transmission via the demultiplexer 2, the line under test 100 and the demultiplexer 6 generates a synchronizing signal based on the burst timing obtained by demodulating the modulated signal. The measurement test etc. are performed in synchronization with.

For example, the communication means 32 in FIG.
As shown by medium "DS22", the DSL signal is received and the modulated signal is output to the demodulation means 31. The demodulation means 31 demodulates the modulated signal, extracts the burst timing, and outputs it to the burst timing synchronization means 30.

Then, for example, the burst timing synchronization means 30 generates a synchronization signal on the terminal side based on the input burst timing, and the control means 33 performs a measurement test or the like in synchronization with the generated synchronization signal.

As a result, the burst timing obtained by the DSL tester 24 on the telephone station side is modulated by the modulating means 27 into a signal in the DSL signal band, and converted into a DSL signal through the line under test or the like, and the DSL tester on the terminal side. By transmitting it to 25 and demodulating it, it becomes possible to synchronize with the burst timing of ISDN communication with a simple configuration.

The burst timing detected by the DSL tester 25 on the terminal side is the modulation means 27, the line under test 1
00 and the demodulation means 31 generate delays respectively in the propagation paths. Therefore, the delay of the propagation path is measured in advance, the delay of the propagation path is set in the DSL tester 25 on the terminal side as delay information, and demodulation is performed. The delay error can be eliminated by correcting the generated burst timing.

Further, the delay information is held in the DSL tester 24 on the telephone station side instead of the DSL tester 25 on the terminal side, and the delay information is transmitted along with the burst timing to be transmitted.
It may be modulated into a signal in the L signal band and transmitted as a DSL signal to the DSL tester 25 on the terminal side via the line under test or the like.

In this case, the DSL tester 25 on the terminal side
Since there is no need to hold delay information in the
It is easy to downsize the L tester 25.

Further, since the delay information can be centrally managed by the DSL tester 24 on the telephone station side, maintenance of the delay information and the like becomes easy.

Regarding the delay correction, the burst timing synchronizing means 30 may correct the demodulated burst timing based on the delay information as described above, or the control means 33 causes the burst timing synchronizing means 30 to generate. The synchronization signal may be synchronized based on the delay information.

[0077]

As is apparent from the above description,
The present invention has the following effects. According to the inventions of claims 1, 2 and 3, the burst timing obtained by the DSL tester on the telephone station side is modulated by the modulating means into a signal in the DSL signal band, and is converted into a DSL signal via the line under test or the like. By transmitting it to the DSL tester on the terminal side and demodulating it, it becomes possible to synchronize with the burst timing of the ISDN communication with a simple configuration.

Further, according to the inventions of claims 4, 5 and 6, the delay of the propagation path is measured in advance and the delay of the propagation path is set as delay information in the DSL tester on the terminal side. The delay error can be eliminated by correcting the demodulated burst timing.

Further, according to the invention of claim 7, the delay information is held in the DSL tester on the telephone station side, and the delay information is modulated into a signal in the DSL signal band together with the burst timing to be transmitted to obtain a DSL signal. The delay error can be eliminated by transmitting to the DSL tester on the terminal side via the line under test or the like. Further, since it is not necessary to hold the delay information in the DSL tester on the terminal side, it is easy to downsize the DSL tester on the terminal side, and the delay information can be centrally managed by the DSL tester on the telephone station side. Maintenance of delay information becomes easy.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a DSL test system according to the present invention.

FIG. 2 is a configuration block diagram showing details of a DSL tester installed on the telephone office side.

FIG. 3 is a configuration block diagram showing details of a DSL tester installed on the terminal (subscriber home) side.

FIG. 4 is a configuration block diagram showing an example of a conventional DSL test system.

FIG. 5 is a configuration block diagram showing details of a DSL tester installed on the telephone station side.

FIG. 6 is a configuration block diagram showing details of a DSL tester installed on the terminal (subscriber home) side.

FIG. 7 is a configuration block diagram showing another example of a conventional DSL test system.

FIG. 8 is a configuration block diagram showing details of a DSL tester installed on the telephone station side.

FIG. 9 is a configuration block diagram showing details of a DSL tester installed on the terminal (subscriber home) side.

[Explanation of symbols]

1 exchange 2, 6 duplexer 3 ISDN clock supply device 7 telephone 4,8,16,17,24,25 DSL tester 5, 9 standard time generator, 10, 18, 26 Burst timing detection means 11,14,19,22,28,32 Communication means 12, 15, 20, 23, 29, 33 Control means 13, 21, 30 Burst timing synchronization means 27 Modulation means 31 demodulation means 100 lines under test 101 standard signal 102 AMI clock signal 103 sync signal

Claims (7)

[Claims] 1. A digital subscriber line test system for performing a measurement test on a line under test in synchronism with ISDN communication, wherein burst timing is detected from an output of an ISDN clock supply device and modulated into a signal in a digital subscriber line signal band. The digital subscriber line tester on the side of the telephone station that transmits the modulated signal transmitted through the line under test, and the modulated signal received through the line under test is demodulated to extract and synchronize the burst timing. A digital subscriber line test system comprising a terminal side digital subscriber line tester. 2. A burst timing detecting means for detecting the burst timing from the output of the ISDN clock supply device by the digital subscriber line tester on the telephone station side, and the burst timing as a signal in a digital subscriber line signal band. And a communication means for transmitting the output of the modulation means via the line under test, and the digital subscriber line tester on the telephone station side as a whole and operating in synchronization with the burst timing. 2. The digital subscriber line test system according to claim 1, further comprising: 3. The communication means, wherein the digital subscriber line tester on the terminal side receives the modulated signal via the line under test, and demodulating means for demodulating the modulated signal to extract the burst timing. A burst timing synchronization means for generating a synchronization signal from the burst timing, and a control means for controlling the entire digital subscriber line tester on the terminal side and operating in synchronization with the synchronization signal. The digital subscriber line test system according to claim 1. 4. The digital subscriber line test system according to claim 3, wherein said burst timing synchronizing means corrects the delay of the burst timing based on delay information of a propagation path. 5. The digital subscriber line test system according to claim 3, wherein said control means corrects the delay of said synchronizing signal based on delay information of a propagation path. 6. The digital subscriber line test system according to claim 4, wherein the delay information of the propagation path is preset in the digital subscriber line tester on the terminal side. 7. The delay information of a propagation path is preset in the digital subscriber line tester on the telephone station side, is modulated into a signal in a DSL signal band together with the burst timing, and is transmitted to the terminal side via the line under test. 6. The digital subscriber line test system according to claim 4 or 5, wherein the digital subscriber line tester is transmitted to the digital subscriber line tester.