CN100501430C - Method and device for measuring insertion loss of digital subscriber line - Google Patents

Abstract

The invention relates to a method and device for testing digital user line inserting consumption. The core is that: taking DMM testing to digital user line to gain the voltage, resistance and capacity parameter of the line; judging whether the line contains the line inserting consumption testing condition based on TDR principle according to the parameters, if it is, taking testing. The invention would select corresponding testing method on special condition of the line. It is based on TDR principle, so it could gain accuracy inserting consumption.

Description

Measure the method and apparatus of insertion loss of digital subscriber line

Technical field

The present invention relates to communication field, relate in particular to a kind of method and apparatus of measuring insertion loss of digital subscriber line.

Background technology

In the telecommunication service field, operator provides broad band telecommunication service and arrowband telecommunication service to the user, as XDSL (X Digital Subscriber Line simultaneously by local cable; Digital subscriber line) business comprises: ADSL over POTS (plain old telephone increase ADSL), ADSL over ISDN (ISDN establishes ADSL newly), VDSL over POTS (plain old telephone increase VDSL), VDSLover ISDN (ISDN establishes VDSL newly) etc. are professional.

The principle that operator provides the XDSL business to the user as shown in Figure 1, XDSL signal and POTS (Plain Old Telephone Service; Plain Old Telephone Service)/ISDN (lntegratedServices Digital Network; ISDN (Integrated Service Digital Network)) signal coexistence is in a user outline, in the local side side, SPL (separation vessel) among the DSLAM (broadband access equipment) comes wide, narrow traffic differentiation, is sent to XDSL business board (broadband services plate) and POTS/ISDN business board (narrowband service board) respectively and handles; And distolateral the user, SPL (separation vessel) then is sent to user side RTU (Remote Terminal Unit with isolated wide, narrow band service; Remote Interface Unit) and phone.

In the operation and maintenance process of this type of business, often need be to the subscriber's line parameter, as, line voltage distribution parameter, line resistance parameter, line capacitance parameter, circuit insert loss, circuit background noise, line-to-ground quality of balance etc. and measure.Broadband line test module among Fig. 1 is realized these parameter testing functions.By the supplemental characteristic of these measurements, can judge the quality and the failure condition of circuit, so which kind of need to determine send the worker to do fault restoration.

In above-mentioned parameter, it is very important parameter in the broadband line test that described circuit inserts the loss parameter, just can estimate the XDSL service rate that circuit can be opened more accurately according to the insertion loss of the professional frequency range of circuit XDSL and the ground unrest of the professional frequency range of circuit XDSL.The broadband line test products has plenty of employing based on TDR (Time Domain Reflection in the market; Time Domain Reflectometry) principle realizes circuit insertion loss test; The broadband line test products that has is to adopt the method that goes out the professional frequency range insertion of the XDSL loss of circuit based on the narrow bandline calculation of parameter.

Prior art one related to the present invention is based on the insertion loss measurement method of TDR principle, its embodiment as shown in Figure 2:

Sending a predominant frequency (representative value is 300K Hz) voltage at local side to local cable is the pulse of Vs, this pulse is transferred to the terminal of local cable from local cable source end, if the terminal of local cable is open circuit or short circuit, this pulse is just all reflected, and reflected impulse is got back to the source end of local cable again; If this predominant frequency voltage that is reflected back toward the pulse of source end is Vf.So, utilize formula to be once obtaining the insertion loss F of cable to this predominant frequency voltage:

F＝0.5×20×LG(Vs/V/f)

(formula one)

(because signal has passed through the cable length decay of twice, so multiply by 0.5 coefficient in this formula).

By technique scheme as can be seen, adopt method that following shortcoming is arranged based on TDR principle measurement insertion loss:

1, because tested reflected impulse will be through the cable length of twice apart from the data acquisition unit that just can get back to local side, when cable was longer, measured reflected impulse amplitude was very little, the test very difficulty that then becomes.For example, if tested cable is a length is 4 kms, diameter is 0.4 millimeter a cable, dominant frequency component is that the pulse of 300KHz is attenuated 14DB for every kilometer, then this pulse is passed to cable termination from the cable source end and will be decayed to 56DB, after terminal is by total reflection, pass to the source end again, be attenuated 56DB again, be attenuated 112DB altogether; Consider the existence of noise in the test environment, so pulse by a small margin is just very difficult tested accurately.

2, when cable termination is in matching status, infeasible based on the insertion loss test of TDR principle.This be because: when terminal was in the matched load state, the burst transmissions of source end emission was all absorbed by matched load to terminal, does not have reflected impulse to return the source end substantially.

Prior art two related to the present invention is based on the method that the narrow bandline calculation of parameter goes out the professional frequency range insertion of the XDSL loss of circuit, and its embodiment is:

Step 1, determine the low-frequency channel model of a twisted-pair feeder, as shown in Figure 3, and according to needed line resistance R of described low-frequency channel Model Calculation and line capacitance C.

C＝c3+(c1×c2)/(c1+c2)

R＝(r1+r2)/2

Step 2, above-mentioned resistance R that obtains and line capacitance C are brought in the formula two, calculate one at f by formula two ₀Preliminary attenuation results X (f on the frequency ₀),

$X\left(f_0\right)=20\mathrm{lo}{g}_{10}e\×\sqrt{\mathrm{\π}\×f_0\×R\×C}$

(formula two)

Wherein, f ₀It is a frequency values.

Step 3, separate f by formula three ₀Trueattenuation Y (the f of the circuit on the frequency ₀):

Y(f ₀)＝k×X(f ₀)+const

(formula three)

In formula three, find by a large amount of tests and calculating, no matter be at 0.4mm line footpath circuit, 0.5mm line footpath circuit or the blend of 0.4mm and 0.5mm footpath circuit, to same f ₀, k and const are constants and constant substantially.As long as earlier to two known f ₀The circuit of frequency decay is tested, and two equations of simultaneous just can be easy to obtain the value of k and two parameters of const.

Step 4, separate pad value on each frequency f by formula four,

$Y\left(f\right)=Y\left(f_0\right)\×\sqrt{\frac{f}{f_0}}$

(formula four)

F in the formula four ₀A span is arranged, and span is between 100K Hz～500K Hz.Determine f ₀Value after, be easy to test and calculate f ₀Pad value Y (the f of place ₀), can be easy to solve Line Attenuation on other frequency according to formula four then.

By the technical scheme of prior art two as can be seen, there is following deficiency in it:

Because electric capacity obtains by the p-wire ground capacitance between circuit, when the twisted-pair feeder sheath does not have ground connection or ground connection in-problem, this method of testing then can't be utilized, and when cable was aging, the insertion loss parameter of utilizing this method of testing to obtain was inaccurate

Summary of the invention

In view of above-mentioned existing in prior technology problem, the purpose of this invention is to provide a kind of method that cable XDSL service frequency bands inserts loss of measuring, by this method, solved when cable is longer, the inaccurate problem of insertion loss test based on the TDR principle, and when cable terminations is in matching status, based on the infeasible problem of insertion loss test of TDR principle; Solved because cable is aging, utilization is inserted the loss test method based on narrow bandline calculation of parameter circuit and is caused testing inaccurate problem, and, insert the problem that the loss test method can't be carried out based on narrow bandline calculation of parameter circuit because cable cover(ing) does not have ground connection.

The objective of the invention is to be achieved through the following technical solutions:

A kind of method of measuring insertion loss of digital subscriber line provided by the invention comprises:

A, digital subscriber circuit are carried out the digital multimeter test, obtain voltage, resistance and the capacitance parameter of described circuit;

B, analyze described circuit according to the described parameter of obtaining and whether possess the condition of inserting loss test based on the circuit of Time Domain Reflectometry principle, if then the insertion loss of described circuit is tested based on the Time Domain Reflectometry principle; Otherwise, the insertion loss of described circuit is calculated based on circuit arrowband parameter.

Wherein, described steps A also comprises:

Digital subscriber circuit is carried out the digital multimeter test, obtains the reference value of the insertion loss of described circuit.

Wherein, described step B specifically comprises:

B1, according to the described parameter analysis circuit cable cover(ing) that obtains ground connection whether, if then the insertion loss of described circuit is tested based on the Time Domain Reflectometry principle; Otherwise, execution in step B2;

B2, analyze described line cord according to the described parameter of obtaining and whether surpass the length that is provided with, if then the insertion loss of described circuit is calculated based on circuit arrowband parameter; Otherwise, execution in step B3;

B3, the insertion loss of described circuit is tested based on the Time Domain Reflectometry principle.

Wherein, described step B also comprises:

B4, the reference value of the test result of described step B3 and digital subscriber circuit being carried out the insertion loss of the described circuit that obtains after the digital multimeter test compare, if the two unanimity, then execution in step B6; Otherwise execution in step B5;

B5, the insertion loss of described circuit is calculated based on circuit arrowband parameter;

B6, report and insert the loss result.

Wherein, before described step B1, also comprise:

BO, analyze described circuit according to described parameter and whether have the arrowband fault, if then report fault warning, and finish test; Otherwise, execution in step B1.

Wherein, after described process of the insertion loss of described circuit being tested, and based on circuit arrowband parameter the insertion loss of described circuit is carried out also comprising after the calculation process: report and insert the loss result described based on the Time Domain Reflectometry principle.

Wherein, described process of the insertion loss of described circuit being tested based on the Time Domain Reflectometry principle specifically comprises:

C1, to send predominant frequency voltage at the source of described circuit end to cable be the pulse of Vs;

C2, when described pulse is sent to terminal, by described end reflection Hui Yuanduan;

C3, the reflection predominant frequency voltage that obtains described pulse at the source of described circuit end are Vf;

C4, according to described voltage Vs and described voltage Vf, utilize formula one to calculate the insertion loss F of described circuit to described predominant frequency voltage Vs:

F=0.5 * 20 * LG (Vs/V/f) formula one.

Wherein, describedly based on circuit arrowband parameter calculation process is carried out in the insertion loss of described circuit and specifically comprises:

D1, determine the low-frequency channel model of a twisted-pair feeder, by described low-frequency channel model measurement and calculate frequency response and calculate needed line resistance R and line capacitance C;

D2, line resistance R and line capacitance C and formula two by calculating calculate at f ₀Preliminary attenuation results X (f on the frequency ₀),

$X\left(f_0\right)=20\mathrm{lo}{g}_{10}e\×\sqrt{\mathrm{\π}\×f_0\×R\×C}$ Formula two

Wherein, f ₀It is a frequency values;

D3, separate f by formula three ₀Trueattenuation Y (the f of the circuit on the frequency ₀):

Y (f ₀)=k * X (f ₀)+const formula three

Wherein, to same f ₀, k and const are constant;

D4, separate pad value on each frequency f by formula four,

$Y\left(f\right)=Y\left(f_0\right)\×\sqrt{\frac{f}{f_0}}$ Formula four

F wherein ₀Span between 100K Hz～500K Hz.

A kind of device of measuring insertion loss of digital subscriber line provided by the invention comprises:

Based on the insertion loss test module of Time Domain Reflectometry test philosophy, go out circuit based on the narrow bandline calculation of parameter and insert the test module of loss and the digital multimeter test module of measurement circuit DC characteristic;

Test by described digital multimeter test module digital subscriber circuit, obtain line voltage distribution, resistance and capacitance parameter; Described parameter is analyzed, selected to go out the test module that circuit inserts loss, the insertion loss of described circuit is tested based on the insertion loss test module of Time Domain Reflectometry test philosophy or based on the narrow bandline calculation of parameter according to analysis result.

Wherein, described digital multimeter test module also is used for digital subscriber circuit and carries out the digital multimeter test, obtains the reference value of the insertion loss of described circuit.

As seen from the above technical solution provided by the invention, the present invention at first digital subscriber circuit carries out Digital Multi-Meter Test, obtains voltage, resistance and the capacitance parameter of described circuit; Analyze described circuit according to the described parameter of obtaining then and whether possess the condition of inserting loss test based on the circuit of TDR principle, if then the insertion loss of described circuit is tested based on the TDR principle; Otherwise, the insertion loss of described circuit is calculated based on circuit arrowband parameter.By the present invention, can be at measurement circuit and select corresponding test method under the certain conditions flexibly, as, long and/or when cable terminations is in matching status when cable, can adopt based on circuit arrowband parameter Calculation Method is carried out in the insertion loss of described circuit, when aging and/or cable cover(ing) does not have ground connection when cable, can adopt the method for the insertion loss of described circuit being tested, therefore can access and insert loss more accurately based on the TDR principle.

Description of drawings

Fig. 1 provides the schematic diagram of XDSL business to the user for operator;

Fig. 2 is the insertion loss measurement schematic diagram based on the TDR principle;

Fig. 3 is the low-frequency channel model structure figure of twisted-pair feeder;

Fig. 4 is the process flow diagram of first embodiment of the invention;

Fig. 5 is the process flow diagram of second embodiment of the invention;

Fig. 6 is the schematic diagram of third embodiment of the invention.

Embodiment

The invention provides a kind of method and apparatus of measuring insertion loss of digital subscriber line, its core is: at first digital subscriber circuit is carried out Digital Multi-Meter Test, obtains voltage, resistance and the capacitance parameter of described circuit; Analyze described circuit according to the described parameter of obtaining then and whether possess the condition of inserting loss test based on the circuit of TDR principle, if then the insertion loss of described circuit is tested based on the TDR principle; Otherwise, the insertion loss of described circuit is calculated based on circuit arrowband parameter.

First embodiment at the method for the invention provides as shown in Figure 4, comprising:

Step S101, digital subscriber circuit is carried out Digital Multi-Meter Test, obtains voltage, resistance and/or the capacitance parameter of described circuit.

Wherein resistance test adopts general electric resistance partial pressure method of testing, and capacity measurement adopts general charging/discharging thereof.

Step S102 analyzes described circuit according to described parameter and whether has the arrowband fault, if then execution in step S103 promptly reports fault warning, and finishes test; Otherwise, execution in step S104.Described arrowband fault judgement comprises following situation: if the line-to-ground alternating voltage surpasses certain thresholding, such as 10 volts, just judge it is that circuit bumps power line failure; If the line-to-ground DC voltage surpasses certain thresholding,, just judge it is its mixed fault of circuit such as 10 volts; If line-to-ground resistance less than certain thresholding, such as 10K ohm, just judges it is line-to-ground insulation difference fault, if line resistance less than certain thresholding, such as 10K ohm, just judges it is insulation difference fault between line; If line mutual-ground capacitor surpasses certain thresholding,, just judge it is the line-to-ground leak current fault such as 1 microfarad.

Step S104, whether ground connection is (if line mutual-ground capacitor is greater than certain thresholding according to the described parameter analysis circuit cable cover(ing) that obtains, such as 0.01 microfarad, just judge cable cover(ing) ground connection), if not, then execution in step S105 promptly tests the insertion loss of described circuit based on the TDR principle, execution in step S109 promptly reports and inserts the loss result then; If the terminal that local cable is described is short circuit, execution in step S106 then.

Wherein, in step S105, described process of the insertion loss of described circuit being tested based on the TDR principle specifically comprises:

Step 1, at local side, promptly sending predominant frequency voltage at the source of described circuit end to local cable is the pulse of Vs;

Step 2, when described pulse is sent to terminal because the terminal short circuit of local cable, therefore described pulse is by described end reflection Hui Yuanduan; The reflection predominant frequency voltage that the source end that is located at described circuit obtains described pulse is Vf;

Step 3, according to described voltage Vs and described voltage Vf, utilize formula one to calculate the insertion loss F of described circuit to described predominant frequency voltage Vs:

F＝0.5×20×LG(Vs/Vf)

(formula one)

Step S106 analyzes described line cord according to the described parameter of obtaining and whether surpasses the length (if line mutual-ground capacitor surpasses certain thresholding, such as 0.2 microfarad, just judging that line cord surpasses the length of setting) that is provided with, if, execution in step S107 then; Otherwise, execution in step S108.

Step S107 calculates the insertion loss of described circuit based on circuit arrowband parameter, then execution in step S109.

In step S107, described based on circuit arrowband parameter the calculation process detailed process to be carried out in the insertion loss of described circuit as follows:

Step 1, determine the low-frequency channel model of a twisted-pair feeder, conciliate the linear equation method and obtain frequency response and calculate needed line resistance and line capacitance by measuring the Z parametric technique.

The low-frequency channel model of determining a twisted-pair feeder still as shown in Figure 3, r1, r2 are the A line and the B line direct current resistance of twisted-pair feeder, g1, g2, g3 be respectively the A line over the ground, the B line reaches the insulation admittance between the A line B line over the ground, c1, c2, c3 be respectively the A line over the ground, the B line reaches the electric capacity between the A line B line over the ground, terminator is made as complex impedance Z.

According to circuit model shown in Figure 3, in order further to reduce difficulty,, regard A line and ground a port of two-port network as with g3, c3 and the synthetic complex impedance z of load Z, with the B line with regard another port of two-port network as.

According to two-port network Z parameter-definition, adding frequency between A line and ground is the alternating voltage Va of f1, measure the electric current 1a and the B line-to-earth voltage Vab of A line, between B line and ground, add the alternating voltage Vb that frequency is f1 again, measure the electric current 1b and the A line-to-earth voltage Vba of B line; According to the Z parameter-definition, obtaining exciting signal frequency is the serial equation of f1:

z11’＝Va/Ia＝Z11’(r1、r2、c1、c2、g1、g2、z)

z22’＝Vb/Ib＝Z22’(r1、r2、c1、c2、g1、g2、z)

z12’＝Vba/Ib＝Z12’(r1、r2、c1、c2、g1、g2、z)

z21’＝Vab/Ia＝Z21’(r1、r2、c1、c2、g1、g2、z)

Equally, the exciting signal frequency that adds on A line or the B line is become f2, obtain serial equation

z11”＝Z11”(r1、r2、c1、c2、g1、g2、z)

z22”＝Z22”(r1、r2、c1、c2、g1、g2、z)

z12”＝Z12”(r1、r2、c1、c2、g1、g2、z)

z21”＝Z21”(r1、r2、c1、c2、g1、g2、z)

Because above-mentioned equation all is a plural form, therefore be actually 16 real coefficient equations.These 16 real coefficient equations can change into 7 linear equations; Obtain r1, r2, c1, c2, g1, g2, these model parameters of z according to these 7 linear equations.

Generally speaking, if circuit is normal, r1 approximates r2, and c1 approximates c2, and c3 approximates 1/3 of c1 or c2; Therefore can obtain:

C＝c3+(c1×c2)/(c1+c2)

R＝(r1+r2)/2

Wherein, R is the average direct current loop resistances of two lines, and C is the comprehensive electric capacity of line-to-line.

Step 2, calculate one at f by formula two ₀Preliminary attenuation results X (f on the frequency ₀),

$X\left(f_0\right)=20\mathrm{lo}{g}_{10}e\×\sqrt{\mathrm{\π}\×f_0\×R\×C}$

(formula two)

Wherein, R is two line direct current loop resistances, and C is the comprehensive electric capacity of line-to-line, f ₀It is a frequency values.

Step 3, separate f by formula three ₀Trueattenuation Y (the f of the circuit on the frequency ₀):

Y(f ₀)＝k×X(f ₀)+const

(formula three)

In formula three, find by a large amount of tests and calculating, no matter be at 0.4mm line footpath circuit, 0.5mm line footpath circuit or the blend of 0.4mm and 0.5mm footpath circuit, to same f ₀, k and const are constants and constant substantially.As long as earlier to two known f ₀The circuit of frequency decay is tested, and two equations of simultaneous just can be easy to obtain the value of k and two parameters of const.

Step 4, separate pad value on each frequency f by formula four,

$Y\left(f\right)=Y\left(f_0\right)\×\sqrt{\frac{f}{f_0}}$

(formula four)

F in the formula four ₀A span is arranged, and span is between 100K Hz～500K Hz.

Determine f ₀Value after, be easy to test and calculate f ₀Pad value Y (the f of place ₀), can be easy to solve Line Attenuation on other frequency according to formula four then.

Step S108 tests the insertion loss of described circuit based on the TDR principle, then execution in step S109.

Step S109 reports and inserts the loss result.

Second embodiment at the method for the invention provides as shown in Figure 5, comprising:

Step S201, digital subscriber circuit is carried out Digital Multi-Meter Test, gets access to voltage, resistance and/or the capacitance parameter of described circuit; And get access to the reference value of the insertion loss of described circuit.

Step S202 analyzes described circuit according to described parameter and whether has the arrowband fault, if then execution in step S203 promptly reports fault warning, and finishes test; Otherwise, execution in step S204.

Step S204, according to the described parameter analysis circuit cable cover(ing) that obtains ground connection whether, if not, then execution in step S205 promptly tests the insertion loss of described circuit based on the TDR principle, and execution in step S211 promptly reports and inserts the loss result then; If, execution in step S206 then.

Wherein, the associated description among the detailed process of described step S205 and first embodiment is identical, is not described in detail here.

Step S206 analyzes described line cord according to the described parameter of obtaining and whether surpasses the length that is provided with, if, execution in step S207 then; Otherwise, execution in step S208.

Step S207 calculates the insertion loss of described circuit based on circuit arrowband parameter, then execution in step S211.

Wherein, the associated description among the detailed process of described step S207 and first embodiment is identical, is not described in detail here.

Step S208 tests the insertion loss of described circuit based on the TDR principle.

Step S209, the reference value of described test result and digital subscriber circuit being carried out the insertion loss of the described circuit that obtains behind the Digital Multi-Meter Test compares, if the two unanimity, then execution in step S211; Otherwise execution in step S210.

Step S210 calculates the insertion loss of described circuit based on circuit arrowband parameter.

Step S211 reports and inserts the loss result.

The invention provides a kind of device of measuring insertion loss of digital subscriber line, its schematic diagram comprises insertion loss test module 310 based on the TDR Test principle, goes out the Digital Multi-Meter Test module 330 of test module 320 that circuit inserts loss, measurement circuit DC characteristic and select module 340 based on the narrow bandline calculation of parameter as shown in Figure 6.

The Digital Multi-Meter Test module 330 of described measurement circuit DC characteristic can be measured subscribers feeder voltage, resistance and capacitance parameter.Wherein voltage parameter comprises A line alternating voltage over the ground as shown in Figure 3, and the B line is alternating voltage over the ground, the alternating voltage between the A line B line, and the A line is DC voltage over the ground, and the B line is DC voltage over the ground, the DC voltage between the A line B line; Resistance parameter comprises A line insulation against ground resistance, B line insulation against ground resistance, the insulation resistance between the A line B line; Capacitance parameter comprises A line ground capacitance, B line ground capacitance, the electric capacity between the A line B line.

Described selection module 340, the circuit arrowband parameter that measures according to DMM are dispatched circuit to insert loss measurement are the insertion loss measurement modules that adopts based on the TDR principle, still adopt the measurement module that inserts loss based on narrow bandline calculation of parameter circuit.

After testing by described Digital Multi-Meter Test module 330 digital subscriber circuit, obtain line voltage distribution, resistance and capacitance parameter; Described parameter is analyzed, produce corresponding signal triggering according to analysis result and select module 340 actions, promptly select to go out the test module 320 that circuit inserts loss, the insertion loss of described circuit is tested based on the insertion loss test module 310 of TDR Test principle or based on the narrow bandline calculation of parameter.

Wherein, described Digital Multi-Meter Test module 330 also is used for digital subscriber circuit and carries out Digital Multi-Meter Test, obtains the reference value of the insertion loss of described circuit.

As seen from the above technical solution provided by the invention, the present invention at first digital subscriber circuit carries out Digital Multi-Meter Test, obtains voltage, resistance and the capacitance parameter of described circuit; Analyze described circuit according to the described parameter of obtaining then and whether possess the condition of inserting loss test based on the circuit of TDR principle, if then the insertion loss of described circuit is tested based on the TDR principle; Otherwise, the insertion loss of described circuit is calculated based on circuit arrowband parameter.By the present invention, can be at measurement circuit and select corresponding test method under the certain conditions flexibly, as, long and/or when cable terminations is in matching status when cable, can adopt based on circuit arrowband parameter Calculation Method is carried out in the insertion loss of described circuit, when aging and/or cable cover(ing) does not have ground connection when cable, can adopt the method for the insertion loss of described circuit being tested, therefore can access and insert loss more accurately based on the TDR principle.

The above; only for the preferable embodiment of the present invention, but protection scope of the present invention is not limited thereto, and anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.

Claims (10)

1, a kind of method of measuring insertion loss of digital subscriber line is characterized in that, comprising:

A, digital subscriber circuit are carried out the digital multimeter test, obtain voltage, resistance and the capacitance parameter of described circuit;

B, analyze described circuit according to the described parameter of obtaining and whether possess the condition of inserting loss test based on the circuit of Time Domain Reflectometry principle, if then the insertion loss of described circuit is tested based on the Time Domain Reflectometry principle; Otherwise, the insertion loss of described circuit is calculated based on circuit arrowband parameter.

2, method according to claim 1 is characterized in that, described steps A also comprises:

Digital subscriber circuit is carried out the digital multimeter test, obtains the reference value of the insertion loss of described circuit.

3, method according to claim 2 is characterized in that, described step B specifically comprises:

B1, according to the described parameter analysis circuit cable cover(ing) that obtains ground connection whether, if then the insertion loss of described circuit is tested based on the Time Domain Reflectometry principle; Otherwise, execution in step B2;

B2, analyze described line cord according to the described parameter of obtaining and whether surpass the length that is provided with, if then the insertion loss of described circuit is calculated based on circuit arrowband parameter; Otherwise, execution in step B3;

B3, the insertion loss of described circuit is tested based on the Time Domain Reflectometry principle.

4, method according to claim 3 is characterized in that, described step B also comprises:

B4, the reference value of the test result of described step B3 and digital subscriber circuit being carried out the insertion loss of the described circuit that obtains after the digital multimeter test compare, if the two unanimity, then execution in step B6; Otherwise execution in step B5;

B5, the insertion loss of described circuit is calculated based on circuit arrowband parameter;

B6, report and insert the loss result.

5, method according to claim 4 is characterized in that, also comprises before described step B1:

B0, analyze described circuit according to described parameter and whether have the arrowband fault, if then report fault warning, and finish test; Otherwise, execution in step B1.

6, according to claim 1 or 3 described methods, it is characterized in that, after described process of the insertion loss of described circuit being tested, and based on circuit arrowband parameter the insertion loss of described circuit is carried out also comprising after the calculation process described based on the Time Domain Reflectometry principle:

Report and insert the loss result.

According to claim 1 or 3 described methods, it is characterized in that 7, described process of the insertion loss of described circuit being tested based on the Time Domain Reflectometry principle specifically comprises:

C1, to send predominant frequency voltage at the source of described circuit end to cable be the pulse of Vs;

C2, when described pulse is sent to terminal, by described end reflection Hui Yuanduan;

C3, the reflection predominant frequency voltage that obtains described pulse at the source of described circuit end are Vf;

C4, according to described voltage Vs and described voltage Vf, utilize formula one to calculate the insertion loss F of described circuit to described predominant frequency voltage Vs:

F=0.5 * 20 * LG (Vs/Vf) formula one.

8, according to claim 1 or 3 described methods, it is characterized in that, describedly based on circuit arrowband parameter calculation process carried out in the insertion loss of described circuit and specifically comprise:

D1, determine the low-frequency channel model of a twisted-pair feeder, by described low-frequency channel model measurement and calculate frequency response and calculate needed line resistance R and line capacitance C;

D2, line resistance R and line capacitance C and formula two by calculating calculate at f ₀Preliminary attenuation results X (f on the frequency ₀),

$X\left(f_0\right)=20{\log }_{10}e\×\sqrt{\mathrm{\π}\×f_0\×R\×C}$ Formula two

Wherein, f ₀It is a frequency values;

D3, separate f by formula three ₀Trueattenuation Y (the f of the circuit on the frequency ₀):

Y (f ₀)=k * X (f ₀)+const formula three

Wherein, to same f ₀, k and const are constant;

D4, separate pad value on each frequency f by formula four,

$Y\left(f\right)=Y\left(f_0\right)\×\sqrt{\frac{f}{f_0}}$ Formula four

F wherein ₀Span between 100K Hz～500K Hz.

9, a kind of device of measuring insertion loss of digital subscriber line is characterized in that, comprising:

Based on the insertion loss test module of Time Domain Reflectometry test philosophy, go out circuit based on the narrow bandline calculation of parameter and insert the test module of loss and the digital multimeter test module of measurement circuit DC characteristic;

Test by described digital multimeter test module digital subscriber circuit, obtain line voltage distribution, resistance and capacitance parameter; Described parameter is analyzed, selected to go out the test module that circuit inserts loss, the insertion loss of described circuit is tested based on the insertion loss test module of Time Domain Reflectometry test philosophy or based on the narrow bandline calculation of parameter according to analysis result.

10, device according to claim 9 is characterized in that, described digital multimeter test module also is used for digital subscriber circuit and carries out the digital multimeter test, obtains the reference value of the insertion loss of described circuit.

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