CN100495045C - A method for examining impedance - Google Patents
A method for examining impedance Download PDFInfo
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- CN100495045C CN100495045C CNB2006100806371A CN200610080637A CN100495045C CN 100495045 C CN100495045 C CN 100495045C CN B2006100806371 A CNB2006100806371 A CN B2006100806371A CN 200610080637 A CN200610080637 A CN 200610080637A CN 100495045 C CN100495045 C CN 100495045C
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Abstract
An impedance testing method, includes the following steps: each sampling channel processes the voltage test on the same test signal, and uses the obtained voltage test value ratio as the channel difference parameter among the sampling channels; connect the voltage output ports of the sampling resistors in the measured impedance and signal source output channel, and the corrected sampling channels respectively test the input voltage of sampling resistor and the input voltage of measured impedance; according to the channel difference parameters and the said voltage test value, obtain the ratio of the voltage true value corresponding to each voltage test value; put the said ratio into the impedance calculation formula of the tested impedance to obtain impedance value. Since the invention processes correction to the sampling channels, obtaining sampling channels difference parameters, and using the parameters to correct the results, so it avoids the impact of the inherent difference of the sampling channels, and further enhances the test precision.
Description
Technical field
The present invention relates to field tests, specifically relate to a kind of impedance detecting 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 plain old telephone increase Asymmetrical Digital Subscriber Line (ADSL overPOTS), ISDN (Integrated Service Digital Network) increase ADSL (ADSL over ISDN), plain old telephone increase Very-high-speed Digital Subscriber Line road (VDSL over POTS), ISDN increase VDSL (VDSL over ISDL) etc., it is quite general that such is applied in home and overseas.
In the operation and maintenance process of this type of business, often need test the subscriber's line parameter, wherein the testing impedance of circuit is an important function, have plenty of the professional frequency range of XDSL that employing derives circuit by measurement circuit low-frequency impedance characteristic such as broadband line test products in the market and insert the method for loss, in the result of the accuracy affects of this method middle impedance test, so require high for the measuring accuracy of impedance.
For impedance detecting method, adopt following two kinds of solutions at present usually.
Technical scheme one:
As shown in Figure 1, when testing, the information source output channel is connected with tested impedance one end by sample resistance, and the information source output channel is exported a signal source Vs, and signal source is through after the signal Processing, be input to sample resistance one end node a, by sample resistance other end node a1 output, tested impedance one end is connected other end ground connection with the node a1 of sample resistance, sampling channel is connected on the node a1, and the magnitude of voltage that records node a1 is V1.If the voltage actual value of sample resistance two ends a, a1 is respectively Va, Val, according to Ohm law and dividing potential drop theory, the impedance of tested impedance can be expressed as:
Z＝Val/Iz＝Val.Rsa/(Va-Val)＝Rsa/(Va/Val-1).................(1)，
The input voltage Va of sample resistance one end economize on electricity a is approximately the signal source output Vs of information source output channel,, obtains relational expression Vs, V1 substitution formula (1):
Z＝Rsa/(Vs/V1-1)..............................(2)，
The numerical value of substitution Vs, V1 just can calculate resistance value by formula (2).
In the technical program, the input voltage of sample resistance is approximated to the signal source output Vs of information source output channel, yet, because signal source is in the transmission course of information source output channel, because the signal Processing of signal and the influence of line impedance, inevitably there is loss, Va compares with Vs, there is decay (for direct current or AC signal) in amplitude, there is skew (for AC signal) in phase place, if, will greatly influence the computational accuracy of impedance obviously with the Va of signal source output Vs value approximate substitution node a.
Technical scheme two:
As shown in Figure 2, the information source output channel is identical in technical scheme one with the annexation of tested impedance, institute's difference is, sampling channel is except the output voltage V al to sample resistance one end node a1 tests, and also the input voltage Va to the other end node a of sample resistance tests.If sampling channel is to node a test, the voltage tester value that obtains is V1, and to node a2 test, the voltage tester value that obtains is V2, and in like manner according to formula (1), with the test value V1 of Va, the test value V2 substitution formula (1) of Val obtains:
Z＝V2/[(V1-V2)/Rsa]＝Rsa/(V1/V2-1)...............(3)，
The numerical value of substitution test value V1, V2 just can calculate resistance value according to formula (3).
With respect to technical scheme one, the technical program is obtained owing to the input voltage value to sample resistance has carried out direct test, and do not take the mode of the Va of signal source output Vs approximate substitution node a, and avoided the transmission attenuation error of information source output channel to signal, improved the precision of impedance relatively; Yet, in the signal testing process, any one signal passes through sampling channel, because the loss of signal in the signal processing, and line impedance loss, inevitably having certain signal attenuation, specifically is that amplitude exists decay (for direct current or AC signal), and there is skew (for AC signal) in phase place.Therefore adopt this technical scheme to test, still have test error, cause resulting impedance precision not high.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of impedance detecting method, to obtain high-precision resistance value.
For solving the problems of the technologies described above, the objective of the invention is to be achieved through the following technical solutions:
A kind of impedance detecting method may further comprise the steps:
Sampling channel is proofreaied and correct; Each sampling channel carries out voltage tester to same test signal, and with the ratio value of each voltage tester value of being obtained, as the channel difference parameter between sampling channel;
Voltage tester: the voltage of the sample resistance on tested impedance and the information source output channel is exported an end be connected, other end ground connection with tested impedance, information source output channel output test signal, the input voltage of sampling channel test sample resistance and the input voltage of tested impedance obtain the voltage tester value;
The result proofreaies and correct: according to described channel difference parameter and voltage tester value, obtain the ratio of the pairing voltage actual value of each voltage tester value;
Impedance computation: the ratio substitution impedance computation formula with described voltage actual value, obtain resistance value.
Method of the present invention, in the sampling channel aligning step, described same test signal is provided by the information source output channel, specifically be on the information source output channel, to choose any node, with the signal of this node as described same test signal.
Method of the present invention, in the sampling channel aligning step, described voltage tester specifically: each sampling channel is connected to described node jointly, and each sampling channel is measured the signal voltage value of the same time of described node, obtains each voltage tester value.
Method of the present invention, described aligning step as a result is specially: described channel difference parameter be multiply by the ratio of described voltage tester value, obtain the ratio of described voltage actual value.
Method of the present invention, described test signal are direct current signal.
Method of the present invention, described test signal are AC signal.
Method of the present invention, described test signal are modulation signal.
Above technical scheme owing to adopted the sampling channel correction, is obtained the sampling channel difference parameter as can be seen, and this parameter reflects the difference of each sampling channel to the attenuation degree of test signal; Adopting described difference parameter to be updated in the impedance computation formula goes, test value is proofreaied and correct, reduced signal in sampling channel sampling test process owing to each sampling channel to the test error that the attenuation degree difference of signal causes, improved the precision of the impedance of gained greatly.
Description of drawings
Fig. 1 is the impedance detecting method synoptic diagram of technical scheme one of the prior art;
Fig. 2 is the impedance detecting method synoptic diagram of technical scheme two of the prior art;
Fig. 3 is the impedance test device synoptic diagram;
Fig. 4 is the synoptic diagram of a kind of sampling channel bearing calibration of the present invention;
Fig. 5 is the synoptic diagram of another kind of sampling channel bearing calibration of the present invention;
Fig. 6 is an impedance detecting method synoptic diagram of the present invention.
Embodiment
Core concept of the present invention is: each sampling channel carries out voltage tester to same signal, obtain each test value, get the difference parameter of the ratio value of each test value as sampling channel, this channel difference parameter is represented the parameter difference of each sampling channel, be specially the influence difference of each sampling channel to the amplitude of the actual signal of test point and phase place, be embodied in each voltage tester value of each sampling channel, with respect to the difference of the attenuation degree of the amplitude of the actual value of this same tested voltage and phase place; The output terminal of tested impedance with the sample resistance of information source output channel sampling channel is connected, according to Ohm law and dividing potential drop theory, the impedance of tested impedance is represented with the resistance value of input, output voltage and the sample resistance of sample resistance, obtained impedance expression; The input voltage of sampling channel test sample resistance and the input voltage of tested impedance obtain the correspondent voltage test value, and described channel difference parameter be multiply by the ratio of described voltage tester value, obtain the ratio of described voltage actual value.And, obtain high-precision resistance value with the described impedance expression of ratio substitution of described described voltage actual value.
In order to make those skilled in the art better understand technical solution of the present invention, be described in further detail below in conjunction with accompanying drawing and specific embodiment.
Be illustrated in figure 3 as the proving installation that is used for testing impedance, this impedance test device comprises system control module, information source output channel, sampling channel, wherein said information source output channel and sampling channel are connected with system control module respectively, are controlled by system control module.The output terminal of described information source output channel is in series with a sample resistance, and the information source output channel is used to export test signal, and sampling channel is used for the sampling test.Wherein information source output channel and sampling channel can increase according to the actual needs of test.
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 is made of digital to analog converter, low-pass filter, operational amplifier and sample resistance.The derived digital signal of system controller output obtains quality test signal preferably through low-pass filtering and the processing of computing amplifying signal after digital to analog converter is converted to simulating signal, be input to sample resistance, through the output of sample resistance dividing potential drop.Sampling channel comprises operational amplifier, low-pass filter and analog to digital converter.After the operational amplifier of sampled signal process sampling channel and low-pass filter carry out signal Processing, be input to analog to digital converter, analog to digital converter is that digital signal is input to system control module with analog signal conversion, by system control module this sampled signal is carried out signal Processing, finish reading and showing or other functions of sampled signal.Wherein sampling channel is a voltage tester passage, and its electric current that flows through can be ignored.
Be illustrated in figure 4 as the synoptic diagram of sampling channel bearing calibration, sampling channel 1 and sampling channel 2 are connected respectively on the node a of information source output channel, information source output channel signal source output, if the voltage actual value of node a is Va, two sampling channels Va are respectively tested, the test result of sampling channel 1,2 is respectively V1, V2, supposes:
A1＝V1/Va................................(4)，
A2＝V2/Va........................(5)，
A＝A1/A2＝V1/V2........................(6)，
Wherein A1, A2 or A can be real number or plural number.
Obviously A1, A2 can be used for representing sampling channel 1,2 attenuation degree to signal Va in signals transmission respectively, so the ratio value of A1, A2 can be used for representing sampling channel 1,2 difference to the attenuation degree of signal in signals transmission.We are called the sampling channel difference parameter with A, will be updated to formula (6) for the numerical value of test value V1, the V2 of Va, Val, just can calculate the value of sampling channel difference parameter.
What deserves to be explained is, in the sampling channel trimming process, as long as guarantee that the signal that each sampling channel tests is identical, might not require this test point must be on the sampling channel certain a bit, perhaps must test simultaneously.Just for convenience, we preferably choose certain a bit on the information source output channel, each sampling channel all is connected to this point, test this signal simultaneously, thereby sampling channel is tested correction.Be illustrated in figure 5 as the method for attachment of the another kind of point of sampling channel bearing calibration, as seen from Figure 5, this scheme is that the node a1 of sampling channel after to sample resistance tested, and obtains the sampling channel difference parameter, and its principle and sampling channel bearing calibration shown in Figure 4 are in like manner.
Be illustrated in figure 6 as impedance detecting method synoptic diagram of the present invention, as shown, with an end ground connection of tested impedance, the other end is connected with the sample resistance of information source output channel, and the information source output signal outputs to tested impedance by sample resistance.The information source output channel is exported a signal source, signal is by a series of signal processing, be input to sample resistance, output to tested impedance by sample resistance, connect situation according to circuit, if the voltage actual value of sample resistance two end node a, a1 should be respectively Va ', Val ', obtain according to Ohm law and dividing potential drop theory:
Z＝Rsa/(Va′/Val′-1)...................(7)。
Sampling channel 1,2 is connected respectively to two end node a, the a1 of sample resistance, respectively two node signals is tested, the test value that 1 couple of node a of sampling channel is surveyed is V1 ', and the measured test value of 2 couples of node a2 of sampling channel is V2 '.
Proofread and correct the result in conjunction with top sampling channel, because employed sampling channel is constant, so sampling channel can think constant to the attenuation degree of signal, and promptly A1, A2, A are constant, therefore have:
Have for sampling channel 1:
Have for sampling channel 2:
Formula (8) and (9) substitution formula (7) are had:
Z＝Rsa/(Va′/Val′-1)＝Rsa/[(V1′/A1/V2′/A2)-1).........(10)。
The numerical value substitution formula (10) of parameter A is consulted in the sampling of being obtained during test value V1 ', V2 ' and sampling channel proofreaied and correct, and just can calculate resistance value Z.
More than a kind of impedance detecting method provided by the present invention is 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 (7)
1, a kind of impedance detecting method may further comprise the steps:
Sampling channel is proofreaied and correct: each sampling channel carries out voltage tester to same test signal, and with the ratio value of each voltage tester value of being obtained, as the channel difference parameter between sampling channel;
Voltage tester: the voltage of the sample resistance on tested impedance and the information source output channel is exported an end be connected, other end ground connection with tested impedance, information source output channel output test signal, the input voltage of sampling channel test sample resistance and the input voltage of tested impedance obtain the voltage tester value;
The result proofreaies and correct: according to described channel difference parameter and voltage tester value, obtain the ratio of the pairing voltage actual value of each voltage tester value;
Impedance computation: the ratio substitution impedance computation formula with described voltage actual value, obtain resistance value.
2, impedance detecting method according to claim 1, it is characterized in that: in the sampling channel aligning step, described same test signal is provided by the information source output channel, specifically be on the information source output channel, to choose any node, with the signal of this node as described same test signal.
3, impedance detecting method according to claim 2, it is characterized in that: in the sampling channel aligning step, described voltage tester is specifically: each sampling channel is connected to described node jointly, each sampling channel is measured the signal voltage value of the same time of described node, obtains each voltage tester value.
4, impedance detecting method according to claim 1 is characterized in that: described aligning step as a result is specially: described channel difference parameter be multiply by the ratio of described voltage tester value, obtain the ratio of described voltage actual value.
5, impedance detecting method according to claim 1 is characterized in that: described test signal is a direct current signal.
6, impedance detecting method according to claim 1 is characterized in that: described test signal is an AC signal.
7, according to claim 5 or 6 described impedance detecting methods, it is characterized in that: described test signal is a modulation signal.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
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| CNB2006100806371A CN100495045C (en) | 2006-05-23 | 2006-05-23 | A method for examining impedance |
| 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 |
| EP07720245A EP2006692A4 (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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| CNB2006100806371A CN100495045C (en) | 2006-05-23 | 2006-05-23 | A method for examining impedance |
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| CN100495045C true CN100495045C (en) | 2009-06-03 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101701971B (en) * | 2009-10-24 | 2011-09-21 | 中北大学 | High-precision multichannel analog signal source |
| US9535102B2 (en) | 2012-05-17 | 2017-01-03 | Yamaha Corporation | Test signal supplying device and semiconductor integrated circuit |
| CN103063926B (en) * | 2012-12-19 | 2016-03-02 | 中国电力科学研究院 | A kind of method of testing of low-voltage power line narrowband carrier termination and proving installation |
| CN104062504B (en) * | 2014-06-13 | 2017-02-22 | 华为技术有限公司 | Super-capacitor detecting circuit |
| CN108414817A (en) * | 2018-02-14 | 2018-08-17 | 黎耀呀 | A kind of integrated circuit of high-precision measuring electricity consumption and electrical leakage |
| CN108594020B (en) * | 2018-04-27 | 2020-05-05 | 陈德文 | Digital display high-sensitivity conductance and high-resistance measuring circuit and method |
| CN109633273B (en) * | 2018-11-30 | 2021-06-04 | 上海无线电设备研究所 | Open-hole load impedance test system and method |
| CN111610358B (en) * | 2020-05-27 | 2022-09-27 | 许昌中科森尼瑞技术有限公司 | Method for calculating residual current by collecting three-phase and zero-sequence currents under three-phase four-wire system |
| CN114280985A (en) * | 2021-12-13 | 2022-04-05 | 航天新长征大道科技有限公司 | Signal output board card and automatic test system |
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Non-Patent Citations (2)
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| 基于DSP的高精度阻抗测量方法及其实现. 武小娟，潘明海，于维双，刘英哲.计量技术，第3期. 2005 |
| 基于DSP的高精度阻抗测量方法及其实现. 武小娟，潘明海，于维双，刘英哲.计量技术，第3期. 2005 * |
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