CN101046492B - Double-port network parameter measuring method - Google Patents
Double-port network parameter measuring method Download PDFInfo
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Abstract
The double port network parameter measuring method includes: correcting the sampling channels and obtaining the sampling channel difference parameter; measuring the input voltage on the sampling resistor and that of the double port network with the corrected the sampling channels; and obtaining the true voltage values with the channel difference parameter and the measured voltage values and calculating the impedance parameters of the double port network with relevant formula. The present invention has raised measurement accuracy.
Description
Technical field
The present invention relates to field of telecommunications, particularly relate to a kind of double-port network parameter measuring method.
Background technology
At field of telecommunications, operator is by local cable (normally twisted-pair feeder), provide broad band telecommunication service and arrowband telecommunication service simultaneously to the user, professional as ADSL over POTS (plain old telephone increase ADSL), ADSL over ISDN (ISDN establishes ADSL newly), VDSL over POTS (plain old telephone increase VDSL), VDSL over ISDN (ISDN establishes VDSL newly) etc., it is quite general that such is applied in home and overseas.
In the operation and maintenance process of this type of business, declare fault such as the user, often need measure 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.According to these supplemental characteristics, judge the quality and the failure condition of circuit, and then determine whether to carry out fault restoration.Because subscriber's line is a typical two-port network, can passes through the method test parameter of tectonic model, thereby derive the actual track parameter.
Two-port network as shown in Figure 1, impedance parameter is promptly
Have according to its characteristic:
Be listed as into equation form:
When I2=0, have
Release
When I1=0, have
Release
This shows, by test port V parameter z1, Vz2, I1, I2 can calculate Z11, Z21, Z12, the value of Z22 is so impedance parameter Z has just obtained.Because data are obtained by test, the test error in the test process directly causes the error of result of calculation, so how to reduce test error, the measuring accuracy that improves parameter just becomes extremely important.
Existing two kinds of method of testings below are described respectively:
The test macro of at first employed two-port network comprises two sampling channels and an information source output channel, and the output terminal of information source output channel is in series with a sampling resistor, and the information source output channel is used to export test signal, and two sampling channels are used for the sampling test.
First method, as shown in Figure 2, this kind method thinks that the signal Va before the sample resistance equals to send source signal Vs, so sampling channel carries out parameter testing only at the sample resistance post-sampling.
According to the two-port network characteristic, when I2=0, have
Release
When I1=0, have
Release
Thereby can obtain impedance parameter by the port voltage value of measured two-port network.
As Z11 is example, and the sample resistance voltage output point a2 on the information source output channel is connected to two-port network terminal 1, and the information source output channel sends a signal source Vs, and this moment, I2=0 had so
Sampling channel is tested at sample resistance voltage output node a2.Be input to sample resistance in the circuit and be respectively Va and Vz1 through the actual signal of voltage that sample resistance outputs to the port one of two-port network, sampling channel is tested Vz1, and the test value that obtains is V2.The voltage Va that will be input to sample resistance in computation process is approximated to and sends signal source signal Vs, according to dividing potential drop theory, formula
Calculate Z11.
According to
The voltage of a2 node is added on two-port network port one and 2 simultaneously, and the magnitude of voltage that two sampling channels record this node is V1, V2, thereby can obtain Z21.
Method in like manner can be obtained Z22, Z12 according to this.
The defective of this method is: think that the sample resistance front signal equals to send signal source Vs, yet the actual signal Va before the sample resistance compares with signal source Vs, because the channel attenuation error of information source output channel, make the amplitude of signal have decay, there is skew in phase place, use the parameter of signal source Vs replacement actual signal Va calculating two-port network so, finally cause influencing greatly the precision of Z parameter;
In order to overcome the defective of first method, so adopt second method usually: sampling channel is at the voltage of sample resistance input node point and pass through the voltage that sample resistance is input to two-port network and take a sample respectively, test its magnitude of voltage, by magnitude of voltage calculation of parameter impedance parameter.
To calculate Z11 is example: as shown in Figure 3: the information source output channel sends a signal source Vs, and this moment, I2=0 according to the two-port network characteristic, had
Voltage input node a1 before sampling channel 1 and the sample resistance is connected, and the real voltage value Va of node a1 is tested; The voltage output node a2 of the port one of sampling channel 2 and two-port network and the sampling resistor of information source output channel is connected, signal source is input to the two-port network port one by sampling resistor, the input signal real voltage value Vz1 of the port one of 2 pairs of two-port networks of sampling channel tests, and the test value of gained is V2.Though the input of the voltage in the circuit before sample resistance node a1, and the actual signal of the port one of two-port network is respectively Va and Vz1, the corresponding measured signal of sampling channel is respectively V1 and V2, according to the dividing potential drop theory, passes through formula
Calculate Z11.
Be connected respectively to terminal 1 and terminal 2 simultaneously to two-port network port one and 2 inputs, one signal, and sampling channel, test at this moment
By
Obtain Z21.
In like manner method can be obtained Z22, Z12 according to this.
For second method, though directly test is by the output voltage values Va of sampling resistor, Vs is approximate to be replaced and do not use, the test error of having avoided the decay of information source output channel relatively and having caused, first method has improved measuring accuracy relatively. but since any one signal by behind the sampling channel, amplitude has decay (direct current or interchange), phase place has skew (interchange), because the inherent loss of sampling channel causes resulting test value and actual value to have deviation; The difference that inevitably has the parameter aspect between while two sampling channels, thereby the real voltage of institute's test point, the amplitude fading on two passages and the degree of phase deviation also can be different. and the test value during with measurement Z11 is an example: for voltage parameter: Va ≠ V1, VZ1 ≠ V2; In addition because each sample channel is different to the attenuation degree of signal, so have
Wherein A1 and A2 are real number or plural number, so have
Therefore finally still there is test error in this method, causes parameter result's degree of accuracy not high.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of method of testing of impedance parameter of high-precision two-port network.
For solving the problems of the technologies described above, (referring to the claim) that the objective of the invention is to be achieved through the following technical solutions:
A kind of double-port network parameter measuring method is provided, it is characterized in that: may further comprise the steps::
Sampling channel is proofreaied and correct: each sampling channel is tested same testing source, gets the ratio of each sampling channel to the voltage tester value of this testing source, as the channel difference parameter between sampling channel;
The voltage parameter test: information source output channel output testing source, described sampling channel is tested the input voltage and the two-port network port voltage of sample resistance, obtains the voltage tester value;
The result proofreaies and correct: according to described channel difference parameter and described voltage tester value, obtain the ratio between the pairing voltage actual value of each voltage tester value.
In method of the present invention, in the sampling channel aligning step, described same testing source is provided by the information source output channel, and any node of choosing on the information source output channel obtains.
In method of the present invention, in the sampling channel aligning step, described test specifically is that each sampling channel is connected to described node jointly, and each sampling channel is measured the signal voltage value of same time.
In method of the present invention, described result proofreaies and correct and is specially: described channel difference parameter be multiply by the ratio of described voltage tester value, obtain the ratio of described real voltage value.
In method of the present invention, described aligning step as a result also comprises: with the ratio substitution two-port network impedance parameter computing formula between the described voltage actual value, obtain impedance parameter.
In method of the present invention, testing source can be chosen direct current signal, AC signal or modulation signal.
Above technical scheme as can be seen, in the present invention owing to carried out the correction calculation of sampling channel, and utilize resulting correction parameter, each test result is proofreaied and correct, and the error of having avoided sample channel difference to be produced has improved the parameter testing precision.In addition, in the present invention, directly the input voltage value of input sample resistance is sampled, and utilize the sampling channel correction parameter that this magnitude of voltage is proofreaied and correct, and the initial output valve of not using the information source output channel is carried out approximate substitution, avoided the fading channel error of information source output channel on the one hand, avoided the sampling error of sample channel on the other hand again, guaranteed that the sampling test value gets high precision.
Description of drawings
Fig. 1 is the two-port network synoptic diagram;
Fig. 2 is a kind of method of testing synoptic diagram of double-port network parameter of the prior art;
Fig. 3 is the another kind of method of testing synoptic diagram of double-port network parameter of the prior art;
Fig. 4 is a test macro synoptic diagram of the present invention;
Fig. 5 is a kind of sampling channel bearing calibration synoptic diagram of the present invention;
Fig. 6 is an another kind of sampling channel bearing calibration synoptic diagram of the present invention;
Fig. 7 is an impedance parameter component Z11 method of testing synoptic diagram of the present invention;
Fig. 8 is an impedance parameter component Z22 method of testing synoptic diagram of the present invention;
Fig. 9 is impedance parameter component Z12 of the present invention, Z21 method of testing synoptic diagram.
Figure 10 is the another kind of method of testing synoptic diagram of impedance parameter component Z12 of the present invention, Z21.
Embodiment
Core of the present invention is: sampling channel is proofreaied and correct, to the identical signal of each sampling channel input, each sampling channel is tested this identical signal, obtains test value, represents channel difference parameter with the ratio of the measured voltage tester value of each sampling channel; Represent the parameter difference of each sampling channel by this channel difference parameter, be specially the influence difference of each sampling channel the amplitude of the actual signal of test point and phase place.Sampling channel is tested the port voltage value of two-port network and the input voltage value of sample resistance, and described channel difference parameter be multiply by the ratio of described voltage tester value, obtains the ratio of described real voltage value.With the ratio substitution two-port network impedance parameter computing formula of described voltage actual value, obtain high-precision impedance parameter.
In order to make those skilled in the art better understand technical solution of the present invention, enforcement of the present invention is described in further detail below in conjunction with accompanying drawing:
The double-port network parameter test macro, as shown in Figure 4, native system comprises system control module, an information source output channel and two sampling channels.The information source output channel is connected with system control module respectively with sampling channel.System control module is used for the test run control of system, comprises the signal output of information source output channel, the test of sampling channel and the processing of test result and demonstration.
This system control module can be selected DSP, CPU or FPGA or its combination for use according to the needs of system.The information source output channel is used to provide testing source, and this passage has digital to analog converter, low-pass filter, operational amplifier and a sampling resistor to constitute.The derived digital signal of system controller output is handled the arrival sample resistance through low-pass filtering and computing amplifying signal after digital to analog converter is converted to simulating signal.The sampling passage comprises operational amplifier, low-pass filter and analog to digital converter.After the signal Processing of sampled signal through operational amplifier and low-pass filter, arrive analog to digital converter, analog signal conversion is that digital signal is input to system control module, by system control module this sampled signal is carried out signal Processing, finishes reading and showing or other functions of sampled signal.
Cited in the present embodiment test macro is the most frequently used double-port network parameter test macro, and the test macro shown in the present embodiment only has an information source output channel and two sampling channels.But in actual applications, can increase a plurality of information source output channels and a plurality of sampling channel, perhaps in each passage, increase the needs of satisfied test such as signal processor according to the test needs.
The sampling channel bearing calibration, as shown in Figure 5, at first send a signal source road information source output channel, signal after digital-to-analog conversion is represented with Vs, the voltage input node a1 that chooses sample resistance is as proofreading and correct test point. disconnect tested network, two sampling channels all are connected with node a1. two sampling channels are tested the voltage of this correction test point a1 simultaneously respectively, and establishing the voltage that sampling channel 1 records is V1, and the voltage that sampling channel 2 records is that V2. sets so
A1, A2 and A can be real number or plural number, so as can be seen by expression formula, A1, A2 reflect the influence of each sampling channel to tested actual signal respectively, specifically be the amplitude of signal and the bias effect of phase place, therefore A1, A2 can be used for representing two passages channel parameters separately, and we are called the channel parameters of sampling channel to them.The ratio A of the channel parameters of corresponding two sampling channels just can represent the difference of two sampling channels, specifically be this two sampling channel of reflection to the difference of the influence of same input signal, specifically be difference degree to the influence of the amplitude of signal and phase place.We are called A the channel difference parameter of sampling channel.
The correction test point that this sampling channel is proofreaied and correct in the test can be arranged on the optional position of information source output channel, and to get signal source identical as long as guarantee to be input to each sampling channel.As shown in Figure 6: different with above-mentioned sampling channel correction is: proofread and correct the electronegative potential one end node a2 place that test point can also be chosen in sample resistance.The channel difference parameter of its sampling channel to obtain computing method the same.
Existing method of testing all is that the acquiescence sampling channel is just the same, but inevitably there are differences between each sampling channel in practice, so the degree of the amplitude fading of same signal on each sampling channel and phase deviation also can be different.Compared with prior art, the present invention is by to the correction of sampling channel, and the error of having avoided the intrinsic difference owing to two sampling channels to produce has significantly improved measuring accuracy.
Double-port network parameter test: at first Z11 or Z22 are example with Z11 in the present embodiment.As shown in Figure 7: disconnect the port 2 of two-port network, the two-port network port one is connected with the electronegative potential one end node a2 and the sampling channel 2 of sample resistance, and the voltage of sample resistance Rsa input node a1 is connected with sampling channel 1 on the information source incoming line.Export a signal source by the information source output channel, signal source is linked into the port one of two-port network by sampling resistor output, this moment I2=0, the real voltage value Va1 of 1 couple of node a1 of sampling channel tests, measured test value is V1, the input voltage actual value Vz1 of the port one of 2 pairs of two-port networks of sampling channel tests, and measured voltage tester value is V2.According to the principle of two-port network, have so
So
Obtain Z11.
According to the result of top sampling channel correction, in conjunction with the circuit-line annexation of present embodiment test: Va1=V1A1, Vz1=V2A2, simultaneously
Derive the ratio between the voltage actual value:
Wherein A1, A2, A are real number or plural number.Z11 is proofreaied and correct substitution ratio:
Obtain:
In like manner, as shown in Figure 8, make I1=0, can obtain Z22, disconnect the two-port network port one, sampling channel 1 and two-port network port 2 are connected with sample resistance voltage output node a2 on the information source output channel, the voltage Vz2 of port 2 is tested, the voltage input node a1 of sampling channel 2 and sampling resistor is connected, and the voltage Va1 of input sample resistance is tested.Import an information source, signal source is input to two-port network port 2 by sample resistance, this moment I1=0, sampling channel 1,2 survey magnitude of voltage be respectively V1, V2.According to the two-port network principle, have
Obtain Z22.
Sampling channel above last same the utilization proofreaies and correct the result and the measurement circuit annexation of this moment obtains: Va1=V2A2, and Vz2=V1A1, simultaneously
Derive the ratio between the voltage actual value:
The expression formula of Z22 above the described ratio substitution is obtained
Test Z12 and Z21 have obtained Z11 and Z22 by top test, concern according to two-port network:
Can calculate Z12 and Z21.Specific as follows:
As shown in Figure 9: the port one, 2 with two-port network is connected with sampling channel 2,1 respectively, voltage output node a2 at the sample resistance of information source output channel is connected with the two- port 1,2 of two-port network, import a signal source, the voltage Va2 test of 1,2 couples of node a2 of sampling channel, measured magnitude of voltage is respectively V1, V2.
Proofread and correct the result and obtain according to top sampling channel: Vz1=V2A2, Vz2=V1A1 in conjunction with the line connecting relation of this test.So the ratio between the voltage actual value is arranged:
Further obtain:
Certainly, when test Z12, Z21, can choose any point on the information source output channel connects respectively as test point rainfall sampling channel, each sampling channel is tested the magnitude of voltage of this test point respectively, as shown in figure 10, different with the represented method of Fig. 9 is, the voltage input node of having chosen sample resistance in the present embodiment is as test point, and is connected with each sampling channel and tests.Its computing method are the same.
In implementation process of the present invention, the information source of each test both can have been imported direct current signal also can input exchange signal can also import the modulation wave signal that multi-frequency superposes, owing in the reality test, often need the test of repeatedly sampling, in actual application, often select modulation wave signal for use with multi-frequency stack.
More than a kind of double-port network parameter measuring method provided by the present invention and system are described in detail, used specific case herein principle of the present invention and embodiment are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.
Claims (8)
1. double-port network parameter measuring method is characterized in that: may further comprise the steps:
Sampling channel is proofreaied and correct: each sampling channel is tested same testing source, with the ratio of each sampling channel to the voltage tester value of described testing source, as the channel difference parameter between sampling channel;
The voltage parameter test: information source output channel output testing source, described sampling channel is tested the input voltage and the two-port network port voltage of sample resistance, obtains the voltage tester value;
The result proofreaies and correct: described channel difference parameter be multiply by the ratio of described voltage tester value, obtain the ratio between the pairing voltage actual value of each voltage tester value.
2. a kind of double-port network parameter measuring method according to claim 1, it is characterized in that: in described sampling channel aligning step, described same testing source is provided by the information source output channel, and any node of choosing on the information source output channel obtains.
3. a kind of double-port network parameter measuring method according to claim 1 and 2, it is characterized in that: in described sampling channel aligning step, described test specifically is that each sampling channel is connected to described node jointly, and each sampling channel is measured the signal voltage value of same time.
4. a kind of double-port network parameter measuring method according to claim 1 is characterized in that: described aligning step as a result further comprises: with the ratio substitution two-port network impedance parameter computing formula of described voltage actual value, obtain impedance parameter.
5. a kind of double-port network parameter measuring method according to claim 1 is characterized in that: described testing source is a direct current signal.
6. a kind of double-port network parameter measuring method according to claim 1 is characterized in that: described testing source is an AC signal.
7. according to claim 5 or 6 described a kind of double-port network parameter measuring methods, it is characterized in that: described testing source is a modulation signal.
8. a kind of double-port network parameter measuring method according to claim 1 is characterized in that: described sampling channel is at least two.
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| CN200610058470A CN101046492B (en) | 2006-03-28 | 2006-03-28 | Double-port network parameter measuring method |
| EP07720245A EP2006692A4 (en) | 2006-03-28 | 2007-02-13 | A sample channel signal calibrating method for impedance testing and an impedance testing method |
| PCT/CN2007/000497 WO2007109964A1 (en) | 2006-03-28 | 2007-02-13 | A sample channel signal calibrating method for impedance testing and an impedance testing method |
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| CN101236247B (en) * | 2008-03-07 | 2010-06-16 | 北京航空航天大学 | Star-carrying multichannel antenna SAR data channel amplitude and phase error correction platform |
| CN103209144A (en) * | 2013-03-15 | 2013-07-17 | 中国电子科技集团公司第二十二研究所 | Relative extraction method for network parameters of transmission line impedance transformer |
| CN106062572B (en) * | 2014-03-04 | 2018-10-30 | 株式会社村田制作所 | The S parameter deriving method of circuit network |
| CN104181392B (en) * | 2014-08-07 | 2016-08-24 | 电子科技大学 | Two-port network phase shift method of testing based on vector network analyzer |
| CN104407229A (en) * | 2014-10-24 | 2015-03-11 | 中国人民解放军国防科学技术大学 | Method for testing capacitance of double-grid field effect transistor |
| CN105182080B (en) * | 2015-09-09 | 2018-01-12 | 浙江大华技术股份有限公司 | A kind of apparatus and method and the network equipment for measuring netting twine impedance |
| CN106771650A (en) * | 2016-11-15 | 2017-05-31 | 中国电子科技集团公司第四十研究所 | A kind of difference multiport device detection modeling method |
| CN106771649A (en) * | 2016-11-15 | 2017-05-31 | 中国电子科技集团公司第四十研究所 | A kind of multiport scattering parameter method of testing for being based on four port vector network analyzers |
| CN112230700A (en) * | 2020-09-29 | 2021-01-15 | 许继电源有限公司 | Output voltage control device |
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| US5748000A (en) * | 1996-08-01 | 1998-05-05 | Hewlett-Packard Company | Error correction method for transmission measurements in vector network analyzers |
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