CN112730983B - Test method for leaky coaxial cable - Google Patents
Test method for leaky coaxial cable Download PDFInfo
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- CN112730983B CN112730983B CN202110054256.0A CN202110054256A CN112730983B CN 112730983 B CN112730983 B CN 112730983B CN 202110054256 A CN202110054256 A CN 202110054256A CN 112730983 B CN112730983 B CN 112730983B
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- 238000010998 test method Methods 0.000 title claims description 5
- 238000012360 testing method Methods 0.000 claims abstract description 68
- 238000001228 spectrum Methods 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims description 15
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 claims description 9
- 230000005540 biological transmission Effects 0.000 abstract description 10
- 238000011156 evaluation Methods 0.000 abstract description 2
- 238000005259 measurement Methods 0.000 description 10
- 230000008878 coupling Effects 0.000 description 6
- 238000010168 coupling process Methods 0.000 description 6
- 238000005859 coupling reaction Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 3
- 238000004891 communication Methods 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 238000007619 statistical method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/16—Spectrum analysis; Fourier analysis
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2688—Measuring quality factor or dielectric loss, e.g. loss angle, or power factor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/083—Locating faults in cables, transmission lines, or networks according to type of conductors in cables, e.g. underground
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- General Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Measurement Of Resistance Or Impedance (AREA)
- Monitoring And Testing Of Transmission In General (AREA)
Abstract
The invention discloses a testing method of a leaky coaxial cable, which comprises the following steps: one end of each of the two test leads is respectively connected with the signal generator and the spectrum analyzer or the equivalent instrument, the other end of each of the two test leads is connected with each other, the frequency of the signal generator is adjusted to the test frequency, the input power is required to ensure that the power of the tail end of the whole section of sample meets the test requirement, the calibration is carried out, and the power level displayed by the spectrum analyzer or the equivalent instrument under the test frequency is recorded as Nin; then judging whether the length of the test sample needs to be segmented, and then measuring the whole segment or the segment. The invention calculates the relative power level by measuring the input power and the output power of the cable, thus realizing the accurate evaluation of the transmission quality of the cable.
Description
Technical Field
The invention relates to the technical field of digital communication cables, in particular to a testing method of a leaky coaxial cable.
Background
With the advancement of wireless communication technology, the application of wireless technology, the development of leaky coaxial cable is vigorous, new technology and new products are continuously developed, in order to ensure transmission quality and transmission distance, a cable with different attenuation constants and coupling losses on continuous length lines is developed, the traditional index for measuring the quality of the cable, namely the attenuation constant and the coupling loss, cannot be accurately measured on the cable, and the transmission quality of the cable cannot be measured, so a new cable testing method is proposed according to the use of the received power level and the power level of the cable input end.
Disclosure of Invention
The invention aims to provide a testing method of a leaky coaxial cable, which can measure the transmission performance of the cable by measuring the received power level.
The invention adopts the technical scheme that:
a method for testing leaky coaxial cable includes the following steps:
a: one end of each of the two test leads is respectively connected with the signal generator and the spectrum analyzer or the equivalent instrument, the other end of each of the two test leads is connected with each other, the frequency of the signal generator is adjusted to the test frequency, the input power is required to ensure that the power of the tail end of the whole section of sample meets the test requirement, the calibration is carried out, and the power level displayed by the spectrum analyzer or the equivalent instrument under the test frequency is recorded as Nin;
b: judging whether the length of the test sample needs to be segmented, wherein when the test sample does not need to be segmented, entering a step C, otherwise, entering a step E;
c: opening one end of a measurement lead wire connected with each other, connecting the other end of the measurement lead wire connected with a signal generator with the head end of a tested sample, then connecting the other end of the measurement lead wire connected with a spectrum analyzer or an equivalent instrument with an antenna, and connecting the tail end of the tested sample with a load;
d: the method comprises the steps that a spectrum analyzer or an equivalent instrument and an antenna are fixedly arranged on a mobile test vehicle, the mobile test vehicle starts from one end of a tested sample, the antenna keeps 2 meters away from the tested sample and moves until the other end of the tested sample, and the receiving power level Nr displayed by the spectrum analyzer or other applicable instruments is recorded;
e: i.e. the test sample is divided into N sequentially connected 1 、N 2 、…、N n The section, firstly, the section of the test sample N1 is passed through the steps C-D to obtain the test sample N 1 Reception power level N of a segment 1 r；
F: then to obtain the test sample N 1 Reception power level N of a segment 1 r as the next adjacent test sample N 2 Repeating steps C-D, and sequentially measuring other segments of the remaining test sample until obtainingLast section of test sample N n Reception power level N of a segment n r；
G: calculating the relative power level by receiving the power level and Nin, namely, evaluating the cable quality;
the measured received power level Nr is characterized by two typical values:
nr50 received power level: finger 50% reception probability, namely: 50% of the measured local received power level is greater than this value;
nr95 received power level: refers to a 95% probability of reception, namely: the local received power level measured at 95% is greater than this value.
The distance between the tested sample and the ground is not less than 10CM.
The difference between the received power level and the cable head-end input power level is formulated as follows:
Dr=Nr-Nin-G
wherein: dr is the relative power level with a reception probability of 95% or 50% in dB; nin is the power level of the cable head end, and the unit is dBm; nr is the received power level in dBm for which the probability in the antenna reception direction is 95% or 50%; g is the antenna gain in db.
The antenna is a half-wave dipole antenna, and the value of G is 0.
The invention calculates the relative power level by measuring the input power and the output power of the cable, thus realizing the accurate evaluation of the transmission quality of the cable.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, the present invention includes the steps of:
a: one end of each of the two test leads is respectively connected with the signal generator and the spectrum analyzer or equivalent instrument, the other end is connected with each other, the frequency of the signal generator is adjusted to the test frequency, the input power is required to ensure that the power of the tail end of the whole section of sample meets the test requirement, the calibration is carried out, and the power level displayed by the spectrum analyzer or equivalent instrument under the test frequency is recorded as the power levelN in ；
B: judging whether the length of the test sample needs to be segmented, wherein when the test sample does not need to be segmented, entering a step C, otherwise, entering a step E;
c: opening one end of a measurement lead wire connected with each other, connecting the other end of the measurement lead wire connected with a signal generator with the head end of a tested sample, then connecting the other end of the measurement lead wire connected with a spectrum analyzer or an equivalent instrument with an antenna, and connecting the tail end of the tested sample with a load;
d: the method comprises the steps that a spectrum analyzer or an equivalent instrument and an antenna are fixedly installed through a mobile test vehicle, the mobile test vehicle starts from one end of a tested sample, the antenna keeps 2 meters away from the tested sample and moves until the other end of the tested sample, and after the completion, the receiving power level Nr displayed by the spectrum analyzer or other applicable instruments is recorded;
e: i.e. the test sample is divided into N sequentially connected 1 、N 2 、…、N n Segment, first for test sample N 1 The section goes through the steps C-D to obtain a test sample N 1 Work of reception of a segmentRate level N 1 r；
F: then to obtain the test sample N 1 Reception power level N of a segment 1 r is used as the input level of the next adjacent section of test sample N2, the steps C-D are repeated, and the other sections of the rest test samples are sequentially measured until the last section of test sample N is obtained n Reception power level N of a segment n r；
G: by receiving power level and N in Calculating the relative power level, namely, evaluating the cable quality;
according to the invention, the cable is distinguished according to the actual condition of the cable, if the single measurement requirement is met, the quality of the cable can be evaluated by measuring the whole section and calibrating the power of the cable firstly, secondly, taking a calibration value as an input value, and then measuring the output power of the whole section by measuring the antenna, wherein the measured result is characterized by the relative power level. Meanwhile, in the cable process, the measuring equipment cannot carry out the whole-section test, the whole-section test is carried out on the cable, the first-section measurement is identical to the whole-section measurement in the measuring process, the steps of the subsequent measuring process are identical to the whole-section measurement except that the input power level is the output end power level of the adjacent upper end of the cable, and the relative power level, namely the quality characterization, can be finally obtained rapidly and accurately.
The following is further described in terms of specific experimental numerical control: the cable was tested 250 meters and required a relative power level of-40 dB or more, with an antenna gain of 0 dB.
And (3) whole-section test: 250 meters of the cable is tested, the input power level is 100dBm, the input test frequency is 3600MHz, the 95% receiving power level is 80dB, and the relative power level Dr=80-100-0= -20dB meets the requirements.
Segment test: the 250 m cable is divided into 5 sections, and each section is 50 m;
the input power level of the first section is 100dBm, the input test frequency is 3600MHz, the measured 95% of the received power level is 80dB, and the power level of the end of the first section is 96.4 dBm;
the input power level of the second section of cable is 96.4 dBm, the 95% of the received power level is 80.5dB, and the power level of the tail end of the second section is 92.5 dBm;
the input power level of the third section of cable is 92.5 dBm, the 95% of the received power level is 81.2dB, and the power level of the tail end of the third section is 88.5 dBm;
the input power level of the fourth section of cable is 88.5 dBm, the 95% of the received power level is 80.7dB, and the power level of the tail end of the fourth section is 84.3 dBm;
the fifth cable input power level was 84.3 dBm, measured 95% of the received power level was 79.8dB,
the relative power level dr=79.8-100-0= -20.2dB, meeting the requirements.
The measured received power level Nr is characterized by two typical values:
nr50 received power level: finger 50% reception probability, namely: 50% of the measured local received power level is greater than this value;
nr95 received power level: refers to a 95% probability of reception, namely: the local received power level measured at 95% is greater than this value. The magnitude of the Nr95% received power level and the Nr50% (median) received power level can be used to characterize the uniformity of the radiated field strength along the length of the cable, which is an automatically set statistical method in existing spectrum analyzers.
The distance between the tested sample and the ground is not less than 10CM, so that the requirements of standard radiation cable division specifications can be met.
The difference between the received power level and the cable head-end input power level is formulated as follows:
dr=nr-Nin-G formula: dr is the relative power level with a reception probability of 95% or 50% in dB; nin is the power level of the cable head end, and the unit is dBm; nr is the received power level in dBm for which the probability in the antenna reception direction is 95% or 50%; g is the antenna gain in db. The antenna is a half-wave dipole antenna, and the value of G is 0.
Transmission attenuation and coupling loss can be measured in segments on leaky coaxial cables that cannot be tested or are not determined by testing the whole length of cable: at different positions of a 350m cable, 2 sections of 50m cables are respectively cut off, the first cable meter is marked with 0-50m, the second cable meter is marked with 300-3500m, the test frequency point is 3600MHz, and the test results are as follows:
the first cable (0-50 m) has a transmission attenuation of 3.6dB and a 95% coupling loss of 85dB
The second cable (300-350 m) has 7.2dB transmission attenuation and 55dB 95% coupling loss
The transmission attenuation and coupling loss of different positions of the cable are greatly different, and the index of any section on the cable cannot represent the overall index level of the cable.
The test method can be used for cables with the requirements of the receiving power level or the difference between the receiving power level and the input power level of the head end of the cable.
In the description of the present invention, it should be noted that, for the azimuth terms, there are terms such as "center", "lateral", "longitudinal
References to orientation and positional relationships such as "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., are based on the orientation or positional relationships shown in the drawings, are merely for convenience of description and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the particular scope of protection of the present invention.
It should be noted that the terms "first," "second," and the like in the description and in the claims of the present application are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the present application described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Note that the above is only a preferred embodiment of the present invention and uses technical principles. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the present invention has been described in connection with the above embodiments, it is to be understood that the invention is not limited to the specific embodiments disclosed and that many other and equally effective embodiments may be devised without departing from the spirit of the invention, and the scope thereof is determined by the scope of the appended claims.
Claims (5)
1. A method for testing a leaky coaxial cable is characterized by comprising the following steps of: the method comprises the following steps:
a: one end of each of the two test leads is respectively connected with the signal generator and the spectrum analyzer or the equivalent instrument, the other end of each of the two test leads is connected with the other end of each of the two test leads, the frequency of the signal generator is adjusted to the test frequency, the input power is required to ensure that the power of the tail end of the whole section of the tested sample meets the test requirement, the calibration is carried out, and the power level displayed by the spectrum analyzer or the equivalent instrument under the test frequency is recorded as the power level Nin of the head end of the cable;
b: judging whether the length of the tested sample needs to be segmented, wherein if the tested sample does not need to be segmented, entering the step C, otherwise, entering the step E;
c: opening one end of a test lead wire connected with each other, connecting the other end of the test lead wire connected with a signal generator with the head end of a tested sample, then connecting the other end of the test lead wire connected with a spectrum analyzer or an equivalent instrument with an antenna, and connecting the tail end of the tested sample with a load;
d: the method comprises the steps that a spectrum analyzer or an equivalent instrument and an antenna are fixedly arranged through a test vehicle, the test vehicle is moved, the antenna is enabled to keep 2 meters away from a tested sample from one end of the tested sample until the other end of the tested sample, and the receiving power level displayed by the spectrum analyzer or the equivalent instrument is recorded;
e: dividing the sample to be tested into N connected in turn 1 、N 2 、…、N n First, for the test sample N 1 The segment passes through the steps C-D to obtain the receiving power level N of the tested sample N1 segment 1 r；
F: then at a received power level N 1 r is used as the adjacent tested sample N 2 Repeating the steps C-D, and sequentially measuring other segments of the rest tested sample until the final tested sample N is obtained n Reception power level N of a segment n r；
G: by the received power level Nr of the whole test sample or the last test sample N n Reception power level N of a segment nr And calculating the relative power level with the power level Nin of the head end of the cable, namely, evaluating the quality of the cable.
2. The method for testing a leaky coaxial cable according to claim 1, wherein: the received power level is characterized by two typical values:
nr50 received power level: finger 50% reception probability, namely: 50% of the measured local received power level is greater than this value;
nr95 received power level: refers to a 95% probability of reception, namely: the local received power level measured at 95% is greater than this value.
3. The method for testing a leaky coaxial cable according to claim 1, wherein: the distance between the tested sample and the ground is not less than 10CM.
4. The test method according to claim 1, wherein: the relative power level calculation formula is as follows:
D r =（Nror (b)N n r）-Nin -G
Wherein:D r the relative power level in dB for a reception probability of 95% or 50%; nin is the power level of the cable head end, and the unit is dBm;Nrand N n r is the antenna connectionA received power level with a probability of 95% or 50% in the reception direction in dBm; g is the antenna gain in db.
5. The method of testing according to claim 4, wherein: the antenna is a half-wave dipole antenna, and the value of G is 0.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110054256.0A CN112730983B (en) | 2021-01-15 | 2021-01-15 | Test method for leaky coaxial cable |
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| CN202110054256.0A CN112730983B (en) | 2021-01-15 | 2021-01-15 | Test method for leaky coaxial cable |
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| CN112730983B true CN112730983B (en) | 2024-04-12 |
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| CN115765794B (en) * | 2022-12-06 | 2024-06-21 | 中国铁塔股份有限公司 | Leaky cable performance evaluation method and device |
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| CN110850239A (en) * | 2019-11-01 | 2020-02-28 | 索亮 | Leaky cable on-line monitoring method and device based on SDR platform and storage medium |
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2021
- 2021-01-15 CN CN202110054256.0A patent/CN112730983B/en active Active
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| KR200304761Y1 (en) * | 2002-10-04 | 2003-02-19 | 주식회사 팬택 | An adapter for measuring RF cable loss coeficient of mobile communication terminal test equipment |
| CN102062818A (en) * | 2010-11-16 | 2011-05-18 | 中天日立射频电缆有限公司 | System for testing performance of leaky cable in simulation tunnel |
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