CN104849592B - A kind of radio telescope wideband electromagnetic shield effectiveness detection system and detection method - Google Patents
A kind of radio telescope wideband electromagnetic shield effectiveness detection system and detection method Download PDFInfo
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- CN104849592B CN104849592B CN201510237882.8A CN201510237882A CN104849592B CN 104849592 B CN104849592 B CN 104849592B CN 201510237882 A CN201510237882 A CN 201510237882A CN 104849592 B CN104849592 B CN 104849592B
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Abstract
The invention discloses a kind of radio telescope wideband electromagnetic shield effectiveness detection system and detection method, which includes transmitting module and receiving module；Transmitting module includes signal source and transmitting antenna, and signal source is used to issue the electric signal of assigned frequency and emitted antenna issues；Receiving module includes frequency spectrograph and receiving antenna, and receiving antenna is used to receive the electric signal of signal source sending, and by received electric signal transmission to frequency spectrograph；Frequency spectrograph is electrically coupled with signal source, to guarantee that the two sends and receives the synchronization of electric signal；Frequency spectrograph receives signal source respectively and is put into the electric signal issued before and after shield, and then calculates the shield effectiveness of shield.The application can detecte that multiple frequency points in frequency band, detection efficiency are high, the influence to tester that avoids manual test and automatically generate testing result report, time saving and energy saving.
Description
Technical field
The present invention relates to electromagnet shield effect detection field more particularly to a kind of radio telescope wideband electromagnetic shield effectiveness
Detection system and detection method.
Background technique
Radio astronomical telescope observes the radio signal very faint from universe, and receiving frequency range can cover from tens
Frequency range of the MHz to GHz up to a hundred.Since radio telescope has high sensitivity, easily receive from the external world and itself
Radio interference, to influence normal operation and Scientific output.With 500 meters of bore spherical radios of national major science and technology infrastructure projects
For telescope (FAST), its working frequency will become the radio of maximum caliber in the world in 70MHz-3000MHz after building up
Telescope, sensitivity is very high, also very high to platform location periphery electromagnetic environment requirements, and the radio interference from ground will affect
The work of radio astronomical telescope.Therefore, 70MHz-3000MHz is proposed to electromagnetic shielding chamber, the shielding cabinet in the FAST station
Frequency inner shield efficiency is greater than the requirement of 120dB, this just needs to carry out stringent electromagnet shield effect test.
The existing test method to shielding body electromagnetic shielding performance is usually to be tested with manual test, single-frequency point, is artificial
Record is arranged and is carried out based on accordance judgement；There are the following problems for it:
1, testing result is imperfect；Since radio telescope observing frequency range is very wide, if selecting limited Frequency point
It is detected, as the frequency point of routine test only surveys tetra- frequencies of 100MHz, 450MHz, 950MHz, 3GMHz in 70MHz-3GMHz
Point causes test result imperfect, and certain frequency points occur cannot meet the requirements, to interfere the normal operation of radio telescope.
2, testing efficiency is low；Due to needing shield to be tested more, if increasing test frequency point, the work of manual test
Amount will increase significantly, and testing efficiency is low.
3, the health of radiation effect tester；Since tester's manual operation will be exposed in radiation field, to survey
The health of examination personnel is unfavorable.
4, test result arranges time-consuming and laborious；Since time-consuming by hand-made testing journal sheet, and test is be easy to cause to tie
Fruit it is not objective.
Therefore, if the technical issues of solving the above problems as those skilled in the art's urgent need to resolve.
Summary of the invention
The problem of for background technique, the purpose of the present invention is to provide a kind of radio telescope wideband electromagnetic screens
Cover efficiency detecting system and detection method, the application can detecte that multiple frequency points in frequency band, detection efficiency is high, avoids hand
It moves the influence tested to tester and automatically generates testing result report, it is time saving and energy saving.
The purpose of the present invention is achieved through the following technical solutions:
A kind of radio telescope wideband electromagnetic shield effectiveness detection system, the detection system includes transmitting module and reception
Module；The transmitting module includes signal source and transmitting antenna, and the signal source is used to issue the electric signal and warp of assigned frequency
The transmitting antenna issues；The receiving module includes frequency spectrograph and receiving antenna, and the receiving antenna is for receiving the letter
The electric signal that number source issues, and by received electric signal transmission to the frequency spectrograph；The frequency spectrograph and the signal source thermocouple
It closes, to guarantee that the two sends and receives the synchronization of electric signal；The frequency spectrograph is received respectively before the signal source is put into shield
The electric signal issued afterwards, and then calculate the shield effectiveness of shield.
Further, the frequency spectrograph is electrically coupled with the signal source by optical fiber realization, is connected without metal therebetween, with
Metal is avoided to connect the influence to shield effectiveness test accuracy.
Further, the detection method based on the detection system includes the following steps:
1) using optical fiber connection frequency spectrograph and signal source, the signal source is made to issue signal and frequency spectrograph reception signal
It is synchronous, and frequency spectrograph is connected with receiving antenna, signal source is connected with transmitting antenna；
2) signal source is controlled according to the power and frequency output signal of setting；
3) it is consistent that the frequency and the signal source for controlling the frequency spectrograph reception signal issue the frequency of signal；
4) frequency spectrograph receives the signal source respectively and is put into the electric signal issued before and after shield, and is automatically stored and connects
The data received；
5) data in step 4) are utilized and calculate the shield effectiveness of shield according to shield effectiveness.
Further, the step 3) specifically: setting will detect the initial frequency of frequency band and terminate frequency, frequency first
The output power of detection frequency point number in section and signal source, then controls the signal source according to the power and rate-adaptive pacemaker of setting
Signal.
Further, the detection method further includes step 6): the shield effectiveness for calculating shield automatically generates screen later
Cover efficiency report.
The present invention has following positive technical effect:
The application can detecte that multiple frequency points in frequency band, detection efficiency are high, avoid manual test to tester
Influence and automatically generate testing result report, it is time saving and energy saving.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of detection system of the invention；
Fig. 2 is the structural schematic diagram that transmitting module of the invention is put into inside shield.
Specific embodiment
Hereinafter, the utility model will be described more fully with reference to the accompanying drawings, shown in the drawings of showing for the utility model
Example property embodiment.However, the utility model can be presented as a variety of different forms, it is not construed as being confined to describe here
Exemplary embodiment.But these embodiments are provided so that this disclosure will be thorough and complete, and by the utility model
Range is fully communicated to those skilled in the art.
The spatially relative terms such as "upper", "lower" " left side " " right side " can be used herein for ease of explanation, for saying
Relationship of the elements or features relative to another elements or features shown in bright figure.It should be understood that in addition in figure
Except the orientation shown, spatial terminology is intended to include the different direction of device in use or operation.For example, if in figure
Device is squeezed, and is stated as being located at other elements or the element of feature "lower" will be located into other elements or feature "upper".Cause
This, exemplary term "lower" may include both upper and lower orientation.Device, which can be positioned in other ways, (to be rotated by 90 ° or is located at
Other orientation), it can be interpreted accordingly used herein of the opposite explanation in space.
It is as follows that electromagnet shield effect tests basic principle:
Shielding is to prevent or reduce a kind of measure of transmission of electromagnetic energy using shield.Shield be to equipment or
Device carries out a kind of closed barrier layer.
The performance of shield is indicated with shield effectiveness.The definition of shield effectiveness is: when being shielded to given external source,
The ratio of electric field strength or magnetic field strength before and after shield is placed on certain point, it may be assumed that
SE in formula --- shield effectiveness, multiple；
E0 --- the electric field strength or magnetic field strength of certain point when unshielded body；
E1 --- place the electric field or magnetic field strength of same point after shield.
According to the definition of the above shield effectiveness, as long as measuring same point respectively under conditions of maintaining like in-field power
The field strength of place shielding front and back, ratio is exactly shield effectiveness, is usually expressed in decibels:
The absolute field strength for measuring certain point is difficult.In shield effectiveness measurement, often need according to tested shield
Size, the corresponding probe of the property of shielding selection, and this kind of probe be usually it is uncertified, even if being surveyed using electromagnetic interference
Amount instrument makees indicating instrument.Also induced voltage can only be measured.
The probe for being generally used for shield EMC measurement belongs to linear unit, that is, the induced voltage popped one's head in is directly proportional to extraneous field strength,
Survey measurements are as follows:
U0=KE0 U1=KE1
U0 in formula --- the induced voltage before shielding on probe；
U1 --- the induced voltage after shielding on probe；
K --- it is related with probe parameter normal.
Shield effectiveness can be indicated with the ratio between the inductive voltage value of shielding front and back on probe in this way, it may be assumed that
The indicating graduation of voltage disturbance measuring instrument is the shield effectiveness as unit of dB μ V are as follows:
SEdB=U0dB-U1dB
Therefore, shield effectiveness is the difference that the decibel on the electromagnetic interference measuring apparatus of shielding front and back counts.
It is the basic principle of shield effectiveness measurement above.But for different size of shield, according to the electric field of selection
Sensor difference, emission source and receiving device are different, and measurement method is discrepant.It is domestic at present for screened room or small-sized
The shield effectiveness measurement of shielding case body respectively has standard:
Large-scale screened room: GB/T 12190-2006
Small-sized shielded box: GJB 5185-2003, GB/T 18663.3-2007
As shown in Figs. 1-2, a kind of radio telescope wideband electromagnetic shield effectiveness detection system of the application, the detection system
Including transmitting module and receiving module；Wherein, transmitting module includes signal source and transmitting antenna, and signal source is for issuing specified frequency
The electric signal of rate and the sending of emitted antenna；Receiving module includes frequency spectrograph and receiving antenna, and receiving antenna is for receiving signal
The electric signal that source issues, and by received electric signal transmission to frequency spectrograph；Frequency spectrograph is electrically coupled with signal source, to guarantee the two hair
It is synchronous with reception electric signal out；Frequency spectrograph receives signal source respectively and is put into the electric signal issued before and after shield, and then calculates
The shield effectiveness of shield out.Wherein, frequency spectrograph selection Agilent N9020A (instrument carries Windows XP operating system,
So control computer is no longer separately configured)；Windows XP operating system: hardware driving management, file operation processing are realized
With network communication services, base layer support is provided for Matlab software.Matlab: realizing that wideband electromagnetic shield effectiveness is tested automatically is
The core function of system, including signal source control, frequency spectrograph control, test data processing, algorithm, data sheet automatically generate function
Energy.Signal source selects Agilent N5181B.
Preferably, the frequency spectrograph is electrically coupled with the signal source by optical fiber realization, is connected without metal therebetween, with
Metal is avoided to connect the influence to shield effectiveness test accuracy.Frequency spectrograph and signal source cooperate.Signal source is placed in screen
Interior is covered, frequency spectrograph is placed in outside screened room.The two is communicated using fiber optic network, no metal contact wires, it is ensured that do not interfere screen
Cover the true shield effectiveness of room.Frequency spectrograph and signal source support LXI (LAN eXtension for instrumentation)
Agreement is run on Ethernet, is used Ethernet protocol completely in network layer, is allowed to simple reformation at based on optical fiber
General network link, order transmission delay are less than 1ms.
Frequency spectrograph operation itself has an operating system, is equivalent to a computer, can be used simultaneously LXI protocol integrated test system frequency
Spectrometer itself and signal source, so that the two can cooperate at a high speed.Meanwhile frequency spectrograph, signal source, control computer three will be needed
The work that platform instrument is completed is integrated to be completed by two instruments.
The frequency that signal source can quickly be changed using network communication after setting a frequency, and then is measured using frequency spectrograph
The power received at the frequency.A Frequency point required time is measured about 3 seconds, much smaller than conventional method.
By taking FAST service band as an example: frequency selects 100 frequency points, similar to Geometric Sequence, covering that can be very intensive
70MHz is to 3GHz wave band, and time of measuring used was less than 5 minutes.Frequency point number can be tested with frequency is started over according to specific
Demand carries out free adjustment.Tetra- frequency points of 100MHz, 450MHz, 950MHz, 3GHz are only measured relative to conventional method, more comprehensively
And quickly cover FAST wave band.After automatic measurement generates Frequency point, an environmental disturbances are measured, it will be by mobile phone
The interference frequency point removal of the frequency ranges such as communication.In this way can intensive coverage test frequency range, and environmental disturbances can be reduced to minimum.
The power that shield effectiveness test receives is subtracted with the power that the test of first step reference level receives again to get arriving
Shield effectiveness.Because being relative measurement, while having another convenience: cable decaying and amplifier need not be demarcated strictly,
It only needs using identical cable and amplifier.
The detection method for being preferably based on detection system includes the following steps:
1) using optical fiber connection frequency spectrograph and signal source, keep signal source sending signal synchronous with frequency spectrograph reception signal, and
Frequency spectrograph is connected with receiving antenna, and signal source is connected with transmitting antenna；
2) signal source is controlled according to the power and frequency output signal of setting；
3) it is consistent to issue the frequency of signal for the frequency and signal source of control frequency spectrograph reception signal；
4) frequency spectrograph receives signal source respectively and is put into the electric signal issued before and after shield, and the number received is automatically stored
According to；
5) data in step 4) are utilized and calculate the shield effectiveness of shield according to shield effectiveness.
Preferably, step 3) specifically: setting will detect in the initial frequency and termination frequency, frequency band of frequency band first
Detection frequency point number and signal source output power, then control the signal source according to setting power and rate-adaptive pacemaker believe
Number.
Preferably, detection method further includes step 6): the shield effectiveness for calculating shield automatically generates shielding effect later
It can report.
The source code of the application is as follows:
Radio telescope wideband electromagnetic shield effectiveness Auto-Test System has obtained in FAST engineering EMC test specific
Using having carried out the measurement of multiple shield effectiveness.Here is in December, 2014 in the progress shield effectiveness measurement of the scene great Wo Dang
Application example.
Test equipment arrangement: indoor transmitting antenna and outdoor 2 meters of receiving antenna spacing, same level height and polarization.Optical fiber
Connection control signal source uniformly chooses 100 measurement points on the index coordinates in 70-3000MHz test scope.Frequency spectrograph is same
Step receives test.
Rope drives 7H electric shield room shield effectiveness test result: the screened room design objective is 70MHz-3000MHz big
In being equal to 120dB, test display 200MHz-2GHz has been met the requirements.The limitation of tested person antenna, 70-200MHz measurement sensitivity
Not enough, low-frequency antenna is replaced herein, and 2GHz above section is not reached due to screened room weld seam and shield door etc. to be wanted
It asks, need to be rectified and improved.
High dynamic range, wideband electromagnetic shield effectiveness Auto-Test System have put into FAST actual measurement of engineering application, are
Unite easy to use, test efficiently, shield effectiveness that 120dB can be tested, test result it is objective and accurate.Solves tradition shielding effect
Can manual test there are the problem of.The electromagnet shield effect in the broadband, high dynamic range that meet radio astronomical telescope requirement is surveyed
Examination demand.
It is described above simply to illustrate that of the invention, it is understood that the present invention is not limited to the above embodiments, meets
The various variants of inventive concept are within the scope of the present invention.
Claims (2)
1. a kind of radio telescope wideband electromagnetic shield effectiveness detection system, which is characterized in that the detection system includes transmitting
Module and receiving module；The transmitting module includes signal source and transmitting antenna, and the signal source is for issuing assigned frequency
Electric signal is simultaneously issued through the transmitting antenna；The receiving module includes frequency spectrograph and receiving antenna, and the receiving antenna is used for
Receive the electric signal that the signal source issues, and by received electric signal transmission to the frequency spectrograph；The frequency spectrograph with it is described
Signal source is electrically coupled, to guarantee that the two sends and receives the synchronization of electric signal；The frequency spectrograph receives the signal source respectively and puts
Enter the electric signal issued before and after shield, and then calculates the shield effectiveness of shield；
The frequency spectrograph is electrically coupled with the signal source by optical fiber realization, is connected without metal therebetween, to avoid metal company
Connect the influence to shield effectiveness test accuracy.
2. the detection method based on detection system described in claim 1, which is characterized in that described method includes following steps:
1) using optical fiber connection frequency spectrograph and signal source, the signal source sending signal and the frequency spectrograph is made to receive signal same
Step, and frequency spectrograph is connected with receiving antenna, signal source is connected with transmitting antenna；
2) signal source is controlled according to the power and frequency output signal of setting；
3) it is consistent that the frequency and the signal source for controlling the frequency spectrograph reception signal issue the frequency of signal；
4) frequency spectrograph receives the signal source respectively and is put into the electric signal issued before and after shield, and is automatically stored and receives
Data；
5) shield effectiveness of shield is calculated using the data in step 4) and according to shield effectiveness；
The step 3) specifically: setting will detect the detection in the initial frequency and termination frequency, frequency band of frequency band first
Then the output power of frequency point number and signal source controls the signal source according to the power and frequency output signal of setting；It is described
Detection method further includes step 6): the shield effectiveness for calculating shield automatically generates shield effectiveness report later.
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| CN112763818B (en) * | 2020-12-18 | 2023-10-13 | 北京无线电计量测试研究所 | Device and method for measuring broadband shielding effectiveness of small shielding body |
| CN117825849A (en) * | 2024-01-02 | 2024-04-05 | 北京航空航天大学 | Cooperative control system and test method for cable shielding effectiveness reverberation room test |
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