【The content of the invention】
It is existing to solve it is an object of the invention to provide a kind of aircraft electromagnetic environment Safety Margin code method
The problem of mode experimentation cost and excessive research and development of products cost.
To achieve the above object, the present invention proposes a kind of aircraft electromagnetic environment Safety Margin code method, is suitable for
Interior of aircraft electromagnetic environment is assessed from compatible secure nargin, and this method comprises the following steps:
(1) confirm by assessment system;
(2) actual (or expected) electromagnetic ambient level of each equipment installation site is determined;
(3) each equipment actual electromagnetic Design of Compatibility control level is determined;
(4) accordance is assessed.
According to above-mentioned main feature, wherein the step of confirming assessment system includes determining that all of each mission phase fly
Machine, system, the various operating modes of equipment, with the possible most extreme electromagnetic environment of clear and definite interior of aircraft, while go out according to equipment
During existing EMC problems to aircraft may caused by consequence and the extent of injury, the influence degree of the mission that carries out to aircraft task, equipment
Functional characteristic, the inconsistency of hardware and related uncertain factor, establish each equipment importance rate and corresponding safety
Margin requirement.
According to above-mentioned main feature, determine that the actual or expected electromagnetic ambient level of each equipment installation site passes through field measurement
Obtain, the whole airborne electronic equipment/electrical equipments of the method order operate at full capacity and switch different working modes, investigate high-power, again
The extreme working position such as the possible most strong transmitting of load equipment, most fast level change rate, most fast power consumption/load switching rate;f≥
During 100MHz, choosing the area equipment cabinets such as head/each equipment compartment of fuselage/tail, cockpit, main cabin, cargo hold space is nearby
Ambient level sampled measurements point, with the scanning frequency spectrum of three axis Field probes+receiver measurement focus;During f≤400MHz, machine is chosen
All connector end interconnecting cables of the area equipment such as head/each equipment compartment of fuselage/tail, cockpit, main cabin, cargo hold are ambient level
Sampled measurements point, with the scanning frequency spectrum of current probe+receiver measurement focus;To scan the largest enveloping of frequency spectrum as expected electricity
Magnetic environment level.
According to above-mentioned main feature, determine that the actual or expected electromagnetic ambient level of each equipment installation site is estimated by analyzing
Determine, can be with conducted susceptibility CS, radiosensitivity in immediate system/device level EMC test standard GJB151A/152A
The experiment limiting level of RS is expected electromagnetic environment electricity;Or the experiment pole with conducted susceptibility CS, radiosensitivity RS in standard
Ration the power supply and be worth based on putting down, depending on installation region situation and neighbouring specific equipment, according to conventional practical experience, increased or decrease some
Value is rationally adjusted.
According to above-mentioned main feature, determine that the actual or expected electromagnetic ambient level of each equipment installation site passes through analogies of experience
Obtain, determined by the data with existing or appropriate correct of selecting similar airplane equipment scene.
According to above-mentioned main feature, determine that the actual or expected electromagnetic ambient level of each equipment installation site passes through simulation calculation
Obtain, by using Large Electromagnetic simulation calculation software kit, such as EM3D, CST, FECO, to fuselage interior structure size, material
Matter, size, trend, the material of laying interconnecting cable in cabin, installation site, size, the material of airborne equipment, equipment it is electrical
The assessment such as energy object, environment, boundary condition carry out as true to nature as possible, detailed modeling, then select suitable time domain, frequency domain value
Algorithm carries out resolving and obtains a result, and the transceiver with antenna can first be considered when calculating by simplifying, and by transmitter radiant power, receives
Machine receiving sensitivity, dual-mode antenna directional diagram and spacing, transmitting-receiving frequency and bandwidth, calculating may deposit between transmitting-receiving fundamental wave, harmonic wave
Interfere with each other influence;Transmitter is considered further that to miscellaneous equipment, according to transmitter transmission power, transmitting antenna directional diagram, hair
Antenna is penetrated to equipment installation site, fuselage screen efficiency is paid close attention to, goes out to launch signal using communication distance equation calculation and concern is set
Standby influence.
According to above-mentioned main feature, determine that each equipment actual electromagnetic Design of Compatibility control level is needed from electromagnetic susceptibility
Consider in terms of level and electromagnetic interference level two, provided by the EMC test reports of equipment;For EMC approved apparatus up to standard, its
Electromagnetic interference level is derived from the Electromagnetic Launching limit value for conducting and radiating in GJB151A, and electromagnetic susceptibility level is surveyed with equipment
Subject to value.
According to above-mentioned main feature, accordance assesses the external interface of slave device, including cabinet and interconnection line radiation and
The aspect of conduction two, respectively each device data obtained by abovementioned steps, substitutes into the following formula and obtains its conduction, radiation safety
Nargin meets implementations:
If:Electromagnetic interference level≤reality (or expected) electromagnetic ambient level -3dB
Electromagnetic susceptibility level >=reality (or expected) electromagnetic ambient level+MIt is required that
At this moment, actual margin of safety MIt is actual=electromagnetic susceptibility level-actual electromagnetic ambient level
If actual margin of safety MIt is actualMore than margin of safety setting MIt is required that, then show that evaluated equipment/system meets to want
Ask.
To realize the object of the invention, the present invention proposes another aircraft electromagnetic environment Safety Margin code method, fits
For aircraft exterior electromagnetic environment Safety Margin, this method comprises the following steps:
(1) confirm by assessment system;
(2) aircraft exterior electromagnetic ambient level is determined;
(3) the fuselage screen efficiency presented in equipment installation site is determined;
(4) each equipment installation site actual electromagnetic field level is determined;
(5) each installation electromagnetical Design of Compatibility control level is determined;
(6) accordance is assessed.
According to above-mentioned main feature, wherein when there are EMC problems according to equipment to aircraft may caused by consequence and harm
Degree, the influence degree of the mission that carries out to aircraft task, the functional characteristic of equipment, the inconsistency of hardware and related not true
Qualitative factor, establishes each equipment importance rate and corresponding margin of safety requirement.
According to above-mentioned main feature, aircraft exterior electromagnetic ambient level EMEL is determinedOutsideThe number that can be directly provided using user
According to or Certification requirement, the much more general regulations quoted in some related platform level electromagnetic compatible standards, also provide specific
The specific quantizating index of application scenarios.
According to above-mentioned main feature, aircraft exterior electromagnetic ambient level EMEL is determinedOutsideAnalysis measurement method can be used to determine, i.e.,
By the various electromagnetic environments that may be met with during analysis of aircraft use, reference, class are chosen wherein than conventional engineering experience
The most harsh typical scene of electromagnetic environment, carries out in-site measurement statistics.
According to above-mentioned main feature, aircraft exterior electromagnetic ambient level EMEL is determinedOutsidePair can be determined using simulation calculation, i.e.,
The most harsh typical scene progress of electromagnetic environment is as true to nature as possible, models in detail.It is every to have the contribution that compare to electromagnetic environment
Radiation source will consider, determine they transmission power, frequency range, signal waveform, antenna directivity, propagation distance,
On the basis of polarization direction etc. is participated in the experiment, the tribute of each field source is calculated with the lossless spatial range formula of electromagnetic wave, communication equation number value
Offer, and carry out vector superposed and synthesize total electromagnetic environment.
According to above-mentioned main feature, the fuselage screen efficiency for determining to present in equipment installation site can use field measurement true
Fixed, to whetheing there is two kinds of situations of aircraft, diverse location, the antenna in orientation are irradiated with safety equivalence level outside machine, to be closed in machine
The received minimum signal level difference of (cockpit, equipment compartment etc.) receiving sensor at position is noted to measure the fuselage screen in place effect ginseng
Number.
According to above-mentioned main feature, the fuselage screen efficiency for determining to present in equipment installation site can use simulation calculation true
It is fixed, such as use electromagnetic-field simulation computation software package, such as EM3D, CST, FECO, to aircraft external and internal compositions size, material, especially
Be cabin inner structure size, the material of installation concern equipment, carry out as true to nature as possible, detailed modeling, then select suitable time domain,
Frequency domain value algorithm is resolved.
According to above-mentioned main feature, the fuselage screen efficiency for determining to present in equipment installation site can use empirical analysis true
It is fixed, i.e., estimated according to engineering experience, the shielding properties in astomous all-metal cabin is best, and the screen for generally having more than 40dB is imitated;
The shielding properties for having the metal cabin of perforation is taken second place;The shielding properties in fenestrate, door metal or non-all-metal cabin is worst, generally
The screen effect of only below 10dB, even strengthens on the contrary in resonant frequency, and general fuselage screen effect selection principle is:
0dB screens effect is corresponding without any shielding measure scene, such as non-conductive matrix material structural region, unshielded open zone
Domain, structure electrical bonding are without support area etc.;
The corresponding seldom shielding measure scene of 6dB screens effect, the cockpit of the non-conductive matrix material fuselage such as only shielded on a small quantity,
Edge, landing gear compartment etc. before and after wing;
Some corresponding shielding measure scenes of 12dB screens effect, as metal aeroplane band crossing cabin connector from rather than full-closed electronic set
Standby cabin, cockpit, without EMI choke grooves door and window/instrument board near zone, such as hydraulic tube, cable bundle, metal are led in these regions
The current-carrying conductors such as wire casing are not on all fine electrical bonding to the crossing cabin connector passed through.
The corresponding medium shielding measure scene of 20dB screens effect, as current-carrying conductor electrical bonding is good, bunch of cables is close to metal structure
The above-mentioned zone of cabling;
The corresponding fine shielding measure scene of 32dB screens effect, as in good full-shield metal cabin.
According to above-mentioned main feature, each equipment installation site actual electromagnetic field level EMEL is determinedIt is interiorFor by aircraft exterior electricity
Magnetic environment level EMELOutsideSubtract airframe shield effectiveness.
According to above-mentioned main feature, determine that each equipment actual electromagnetic Design of Compatibility control level is needed from electromagnetic susceptibility
Consider in terms of level and electromagnetic interference level two, provided by the EMC test reports of equipment;For EMC approved apparatus up to standard, its
Electromagnetic interference level is derived from the Electromagnetic Launching limit value for conducting and radiating in GJB151A, and electromagnetic susceptibility level is surveyed with equipment
Subject to value.
According to above-mentioned main feature, accordance assesses the external interface of slave device, including cabinet and interconnection line radiation and
The aspect of conduction two, respectively each device data obtained by abovementioned steps, substitutes into the following formula and obtains its conduction, radiation safety
Nargin meets implementations:
Electromagnetic interference level EMILControl≤ it is expected electromagnetic ambient level EMELIt is interior- 3dB
Electromagnetic susceptibility level EMSLControl>=it is expected electromagnetic ambient level EMELIt is interior+M
If margin of safety M=electromagnetic susceptibility level EMSLControl- it is expected electromagnetic ambient level EMELIt is interiorMore than defined
Value, then show that evaluated equipment/system is met the requirements.
To realize the object of the invention, the present invention proposes another aircraft electromagnetic environment Safety Margin code method, fits
For aircraft exterior electromagnetic environment Safety Margin, this method comprises the following steps:
(1) confirm by assessment system;
(2) aircraft exterior electromagnetic ambient level is determined;
(3) device-dependent reflux framework is established;
(4) Injection Current is calibrated, it includes low level scanning and irradiation and is injected with low level surface current of equal value;
(5) high level surface current injection method airworthiness compliance is tested.
According to above-mentioned main feature, the step of Injection Current is calibrated, includes configuration suitably by test specimen earthing mode and ground connection
Point position, first carries out low level irradiation, is closed with the sensing electric current in cable caliper measurements apparatus interconnection cable, then to airframe
Suitable point injection low level current, is sized, and makes to monitor to sense electric current and the measured value on the interconnecting cable of concern equipment
It is identical, the transfer function between irradiation field strength and Injection Current is thus obtained, is extrapolated using the linear relationship between low and high level
Sense electric current on aircraft skin under the high level irradiation field of standard requirement, this should be directly injected into current value, finally keep flying
The Current injection points of machine, earthing mode and earth point position are constant, and the high current is injected to aircraft skin.
To realize the object of the invention, the present invention proposes another aircraft electromagnetic environment Safety Margin code method, fits
For aircraft exterior electromagnetic environment Safety Margin, this method comprises the following steps:
(1) confirm by assessment system;
(2) aircraft exterior electromagnetic ambient level is determined;
(3) aircraft low level is scanned in the machine of determining by sensing electric current or installation place external electromagnetic field on test specimen interconnecting cable
Transmission function;
(4) linear extrapolation goes out on interconnecting cable corresponding with aircraft exterior electromagnetic ambient level to sense electric current or installation place is empty
Between electromagnetism field value;
(5) cable current injection or irradiation, and accordance assessment are carried out with the high level.
According to above-mentioned main feature, this method is applicable in frequency range and divides LLSCI, LLSC and LLSF tri- kinds, and LLSCI is suitable for
10KHz~aircraft 1st resonant frequencies, LLSC are suitable for 500kHz~400MHz that cable plays main coupling, and LLSF is applicable in
In all influential 100MHz~40GHz of cabinet and cable, the method establishes electromagnetism on the airborne equipment of concern in a manner of surveying
Transmission function relation between effect and aircraft exterior electromagnetic environment, wherein LLSCI, LLSC are induced electricity on apparatus interconnection cable
Stream is connected with normalization aircraft exterior electromagnetic environment, and LLSF is equipment installation place field strength and normalization aircraft exterior electromagnetism
Environment connects, then transmission function linear extrapolation must be assessed equipment should be applied under the aircraft exterior electromagnetic environment of requirement accordingly
The interior of aircraft electromagnetic stress added, so as to carry out substituting indirect test verification.
Compared with prior art, the present invention realizes aircraft electromagnetic environment Safety Margin by above-mentioned method,
This method strong operability, has practical directiveness well, can significantly improve the work efficiency that such assessment is carried out in engineering, drop
Low expense, contributes to the aircraft-level seaworthiness of the civil aircraft of China's implementation at the startup to take, the development of certification work.
【Embodiment】
Refering to Figure 1, the present invention discloses a kind of aircraft electromagnetic environment Safety Margin code method, it is based on outer
Some accommodations of the response of equal value of galvanomagnetic-effect of equal value and/or EUT functional performances that portion's electromagnetic environment EME stress produces EUT
Equivalent Test method, mainly includes the following steps:(1) confirm by assessment system;(2) aircraft exterior electromagnetic ambient level is determined;
(3) suitable method is selected to determine external electromagnetic environment and the transmission function of electromagnetic environment at internal focus;(4) according to transmission letter
The definite focus actual electromagnetic field level of number;(5) each installation electromagnetical Design of Compatibility control level is determined;(6) accordance is assessed.
The present invention has standardization effect, strong operability, tool by above-mentioned method to the work of aircraft electromagnetic environment Safety Margin
There is practical directiveness well, the work efficiency that such assessment is carried out in engineering, reduction expense can be significantly improved.As for above-mentioned side
The particular content of each step in method, the specific descriptions in four embodiments that can be below.
Margin of safety Margin refers to the difference of actual interference level in sensitive thresholding and environment, commonly uses dB and represents.The electricity of aircraft
Magnetic environment margin of safety is the difference of sensitive thresholding and environment the actual interference level of airborne most sensitive equipment/system, excessively generally.
The specific electromagnetic environment margin of safety of each airborne equipment/system is more paid close attention in engineering, they are general different, so aircraft
Electromagnetic environment margin of safety be really minimum value in the electromagnetic environment margin of safety of each airborne equipment/system.
1. interior of aircraft electromagnetic environment is assessed from compatible secure nargin
Refer to aircraft the machine whole machine in internal electromagnetic environment Electromagnetic Environment Level-EMEL
The largest enveloping for the full machine electromagnetic ambient level that on-board electrical electronic system, equipment energization work are formed, it is abundant from compatible secure
Degree assessment mainly includes following 4 steps:
(1) confirm by assessment system;
(2) actual (or expected) electromagnetic ambient level of each equipment installation site is determined;
(3) each equipment actual electromagnetic Design of Compatibility control level is determined;
(4) accordance is assessed
As shown in Figure 2, specific embodiment 1 is shown in the narration in detail of each step to estimation flow figure.
2. aircraft exterior electromagnetic environment Safety Margin (fuselage screen is followed)
This is a kind of indirect assessment method.External electromagnetic environment Electromagnetic Environment Level-
EMEL refers to the largest enveloping for the full machine external electromagnetic environment level that aircraft is likely to be at outside, substantially it is considered that locating on aircraft skin
It is same value to locate equal.Aircraft exterior electromagnetic environment Safety Margin mainly includes following 6 steps:
1) confirm by assessment system;
2) aircraft exterior electromagnetic ambient level is determined;
3) the fuselage screen efficiency presented in equipment installation site is determined;
4) each equipment installation site actual electromagnetic field level is determined;
5) each installation electromagnetical Design of Compatibility control level is determined;
6) accordance is assessed.
As shown in Figure 3, specific embodiment 2 is shown in the narration in detail of each step to estimation flow figure.
3. aircraft exterior electromagnetic environment Safety Margin (high level surface current injection method)
HIRF irradiation, which is substituted, with Bulk current injection method carries out actual test, verification.Directly to the big electricity of fuselage skin injection
Stream, generates needed for aircraft exterior electromagnetic environment Safety Margin electromagnetic environment in machine, makes to be in by test specimen and high level outside machine
Under the electromagnetic stress of irradiation field equivalence, so as to produce same response.
It is alternate test assessment, one of advantage is an overall test just while completes to pacify the EMC of all airborne equipments
Full nargin assessment.Its most effective frequency of use scope 10kHz~1st aircrafts resonant frequency (generally aircraft maximum dimension 150~
30 meters of corresponding electromagnetic wave half-wavelengths, 1~5MHz), 400MHz is can be extended to, then high-frequency makes bad stability.Assessment is main
Including following 5 steps:
1) confirm by assessment system;
2) aircraft exterior electromagnetic ambient level is determined;
3) device-dependent reflux framework is established;
4) Injection Current is calibrated
A) low level scanning and irradiation;
B) low level surface current injection of equal value.
5) high level surface current injection method airworthiness compliance is tested.
Estimation flow figure is as shown in figure 4, in view of length is no longer illustrated in detail.
4. aircraft exterior electromagnetic environment Safety Margin (low level coupled method)
Belong to alternative, divide LLSCI, LLSC and LLSF tri- kinds by applicable frequency range.LLSCI is suitable for 10KHz~aircraft 1st
Resonant frequency, LLSC are suitable for 500kHz~400MHz that cable plays main coupling, and LLSF is suitable for cabinet and cable
Influential 100MHz~40GHz.The reason for the overlapping use of latter two method it is major electromagnetic in 100~400MHz frequency ranges
Coupling mechanism and field source characteristic, field source/object construction material, field source and target spacing, medium factors are closely related.Usually
Cable induced electricity stream plays main coupling on flivver, and space electric field plays main coupling on big aircraft.So herein frequently
General both of which is used in section, in order to avoid omit harsher electromagnetic environment scene.Pass is established in low level coupling in a manner of surveying
Transmission function relation on the airborne equipment of note between galvanomagnetic-effect and aircraft exterior electromagnetic environment, i.e., LLSCI, LLSC are equipment
Sense electric current on interconnecting cable to connect with normalization aircraft exterior electromagnetic environment, LLSF is equipment installation place field strength and normalizing
Change aircraft exterior electromagnetic environment to connect.Transmission function linear extrapolation must assess the aircraft exterior electromagnetic environment of requirement accordingly again
The interior of aircraft electromagnetic stress that equipment should be applied down, so as to carry out substituting indirect test verification.Assessment mainly includes following 5
A step:
1) confirm by assessment system;
2) aircraft exterior electromagnetic ambient level is determined;
3) aircraft low level scanning (Injection Current, irradiation) is asked in machine by sensing electric current or installation on test specimen interconnecting cable
Locate the transmission function of external electromagnetic field;
4) linear extrapolation goes out on interconnecting cable corresponding with aircraft exterior electromagnetic ambient level to sense electric current or installation place is empty
Between electromagnetism field value;
5) cable current injection or irradiation, and accordance assessment are carried out with the high level.
Estimation flow figure as shown in Figure 5, in view of length is no longer illustrated in detail.
For the understanding apparent to above-mentioned method, above-mentioned method is said respectively with specific example below
It is bright.
1. interior of aircraft electromagnetic environment of example is assessed from compatible secure nargin
1) confirm by assessment system
Consider all aircrafts, system, the various operating modes of equipment of each mission phase, thus clear and definite interior of aircraft may
Most extreme electromagnetic environment.When there are EMC problems according to equipment at the same time to aircraft may caused by consequence and the extent of injury, to flying
Machine carries out the influence degree of mission task, the functional characteristic of equipment, the inconsistency of hardware and related uncertain factor,
Establish each equipment importance rate and the requirement of corresponding margin of safety, usual safe level is 12dB, task level 6dB, and regular grade is
0dB;
2) actual (or expected) the electromagnetic ambient level EMEL of each equipment installation site is determinedIt is interior
EMELIt is interiorIt is the benchmark that aircraft is assessed from compatible secure nargin, can be used to lower several method and determine.
Field measurement:Whole airborne electronic equipment/electrical equipments is operated at full capacity and switch different working modes, it is main to investigate
The limit work such as high-power, the possible most strong transmitting of heavy load equipment, most fast level change rate, most fast power consumption/load switching rate
Make state.During f >=100MHz, the area equipment cabinets such as head/each equipment compartment of fuselage/tail, cockpit, main cabin, cargo hold are chosen
Neighbouring space is ambient level sampled measurements point, with the scanning frequency spectrum of three axis Field probes+receiver measurement focus;f≤
During 400MHz, it is mutual to choose all connector ends of area equipment such as head/each equipment compartment of fuselage/tail, cockpit, main cabin, cargo hold
Even cable is ambient level sampled measurements point, with the scanning frequency spectrum of current probe+receiver measurement focus;To scan frequency spectrum
Largest enveloping is expected electromagnetic ambient level EMELIt is interior。
Analysis estimation:System/device level electromagnetic compatible testing standard GJB151A/152A has fully taken into account airborne set
The electromagnetic environment being likely encountered during standby installation experiment, directly takes the examination of conducted susceptibility CS, radiosensitivity RS in standard
It is expected electromagnetic ambient level EMEL to test limiting levelIt is interior;Or the experiment pole with conducted susceptibility CS, radiosensitivity RS in standard
Ration the power supply and be worth based on putting down, depending on installation region situation and neighbouring specific equipment, according to conventional practical experience, increased or decrease some
Value is rationally adjusted.
Analogies of experience:Select the data with existing of similar airplane equipment scene, or appropriate amendment.
Simulation calculation:Use Large Electromagnetic simulation calculation software kit, such as EM3D, CST, FECO, to fuselage interior knot
Structure size, material, size, trend, the material of the interior laying interconnecting cable of cabin, installation site, size, the material of airborne equipment,
The assessment such as electrical property of equipment object, environment, boundary condition carry out as true to nature as possible, detailed modeling.When selecting suitable again
Domain, frequency domain value algorithm carry out resolving and obtain a result.The transceiver with antenna can first be considered when calculating by simplifying, by transmitter spoke
Power, receiver receiving sensitivity, dual-mode antenna directional diagram and spacing, transmitting-receiving frequency and bandwidth are penetrated, calculates transmitting-receiving fundamental wave, harmonic wave
Between that may be present interfere with each other influence;Transmitter is considered further that to miscellaneous equipment, according to transmitter transmission power, transmitting antenna
Directional diagram, transmitting antenna go out to launch signal to equipment installation site, fuselage screen efficiency is paid close attention to using communication distance equation calculation
Influence to paying close attention to equipment.
3) each equipment actual electromagnetic Design of Compatibility control level is determined
The EMC margins of safety of so-called aircraft are too general, and the equipment of different importance rates has the requirement of different margins of safety,
The equipment of same hierarchically secure margin requirement also has different actual margins of safety.So the EMC margins of safety of aircraft are final
To specifically it implement in each equipment.The electromagnetic Compatibility Design control level of every equipment is, it is necessary to electric from electromagnetic susceptibility
Flat Electromagnetic Susceptibility Level-EMSLControlWith electromagnetic interference level Electromagnetic
Interference Level─EMILControlConsider in terms of two.It can generally be provided by the EMC test reports of equipment.For EMC
Approved apparatus up to standard, its EMILControlSuch as more conservative Electromagnetic Launching limit value that may be derived from conducting and radiating in GJB151A, and EMSLControl
It should then be subject to equipment measured value.
4) accordance is assessed
The external interface of slave device-- cabinet and interconnection line are set about so as to radiate and conduct two aspects, respectively by above
Each device data that a few section methods obtain, substitution the following formula obtains its conduction, radiation safety margin meets implementations.
If:Electromagnetic interference level≤reality (or expected) electromagnetic ambient level -3dB
Electromagnetic susceptibility level >=reality (or expected) electromagnetic ambient level+MIt is required that
At this moment, actual margin of safety MIt is actual=electromagnetic susceptibility level-actual electromagnetic ambient level
If actual margin of safety MIt is actualMore than margin of safety setting MIt is required that, then show that evaluated equipment/system meets to want
Ask.Here not only consider to be assessed from the electromagnetic susceptibility level of safety margin definition, also add to Electromagnetic Launching level
Assessment, to internal electromagnetic ambient level EMELIt is interiorIncrease some safety factors.
2. aircraft exterior electromagnetic environment Safety Margin of example (fuselage screen is followed)
1) confirm by assessment system
With example 1 1), general middle and high degree spatial domain electromagnetic environment is preferable, and ground or low latitude electromagnetic environment are harsher, and airport is attached
Closely, the electromagnetic environment on warship shutdown deck is harsher.
2) aircraft exterior electromagnetic ambient level EMEL is determinedOutside
EMELOutsideIt is the benchmark for carrying out the assessment of external electromagnetic environment compatible secure nargin.Lower several method is can be used to determine.
User requires:The data directly provided using user or the requirement of Certification, it is flat generally to quote some correlations more
Regulation in platform level electromagnetic compatible standard, also there is the specific quantizating index for providing application-specific scene.
Analysis actual measurement:The various electromagnetic environments that may be met with during analysis of aircraft use, reference, class are than conventional engineering
Experience, chooses the wherein most harsh typical scene of electromagnetic environment, carries out in-site measurement statistics.
Simulation calculation:The typical scene progress most harsh to electromagnetic environment is as true to nature as possible, models in detail.It is every to electricity
The radiation source that magnetic environment has the contribution that can compare will consider, determine they transmission power, frequency range, signal waveform, day
On the basis of line directionality, propagation distance, polarization direction etc. are participated in the experiment, with the lossless spatial range formula of electromagnetic wave, communication equation
The contribution of each field source of numerical computations, and carry out vector superposed and synthesize total electromagnetic environment.
3) the fuselage screen efficiency FSE presented in equipment installation site is determined
Integral body shield effectiveness seems excessively rough in engineering, and the fuselage that concerned equipment installed position shows
Shield effectiveness more has practical value.So when definition whether there is aircraft here, somewhere sensor received signal level ratio is in machine
The fuselage screen effect that the point is presented.Determined with following several method.
Field measurement:To whetheing there is two kinds of situations of aircraft, diverse location, the antenna in orientation are with safety equivalence level spoke outside machine
According to the received minimum signal level difference of (cockpit, equipment compartment etc.) receiving sensor is the measurement ground at concerned position in machine
The fuselage screen effect parameter of point.
Simulation calculation:Using electromagnetic-field simulation computation software package, such as EM3D, CST, FECO, to aircraft external and internal compositions ruler
Cabin inner structure size, the material of very little, material, especially installation concern equipment, carry out as true to nature as possible, detailed modeling, then select
Resolved with suitable time domain, frequency domain value algorithm.
Empirical analysis:Estimated according to engineering experience, the shielding properties in astomous all-metal cabin is best, generally there is 40dB
Screen effect above;The shielding properties for having the metal cabin of perforation is taken second place;Fenestrate, door metal or the shielding in non-all-metal cabin
Can be worst, the screen effect of general only below 10dB, even strengthens on the contrary in resonant frequency.General fuselage screen imitates selection principle:
0dB screens effect is corresponding without any shielding measure scene, such as non-conductive matrix material structural region, unshielded open zone
Domain, structure electrical bonding are without support area etc.;
The corresponding seldom shielding measure scene of 6dB screens effect, the cockpit of the non-conductive matrix material fuselage such as only shielded on a small quantity,
Edge, landing gear compartment etc. before and after wing;
Some corresponding shielding measure scenes of 12dB screens effect, as metal aeroplane band crossing cabin connector from rather than full-closed electronic set
Standby cabin, cockpit, without EMI choke grooves door and window/instrument board near zone, such as hydraulic tube, cable bundle, metal are led in these regions
The current-carrying conductors such as wire casing are not on all fine electrical bonding to the crossing cabin connector passed through.
The corresponding medium shielding measure scene of 20dB screens effect, as current-carrying conductor electrical bonding is good, bunch of cables is close to metal structure
The above-mentioned zone of cabling;
The corresponding fine shielding measure scene of 32dB screens effect, as in good full-shield metal cabin.
4) each equipment installation site actual electromagnetic field level is determined
Aircraft exterior electromagnetic ambient level EMELOutsideAirframe shield effectiveness FSE is subtracted, just obtains each equipment installation position
Put actual electromagnetic field level EMELIt is interior。
EMELIt is interior=EMELOutside- FSE
5) each installation electromagnetical Design of Compatibility control level is determined
With 3) saving for example 1.
6) accordance is assessed
With 4) saving for example 1.
3. aircraft exterior electromagnetic environment Safety Margin of example (high level surface current injection method)
Experiment process is:Configuration suitably by test specimen earthing mode and earth point position (with actual installation state consistency or
Carried out easy to test), low level irradiation is first carried out, with the sensing electric current in cable caliper measurements apparatus interconnection cable, then to flying
Machine fuselage appropriate point injects low level current, is sized, make to monitor to sense on the interconnecting cable of concern equipment electric current with
The measured value is identical, thus obtains the transfer function between irradiation field strength and Injection Current.Using linear between low and high level
Sense electric current on aircraft skin under the high level irradiation field of relation extrapolation standard requirement, this should be directly injected into current value.Most
Keep the Current injection points, earthing mode and earth point position of aircraft constant afterwards, the high current is injected to aircraft skin.Inductive step
It is rapid as follows:
1) with low level EOuter lowElectromagnetic Field Irradiation aircraft;
2) the sensing electric current of detection concern all interconnecting cables of equipment, is stuck in away from cable under test at cabinet 50mm with current clamp
On, measurement wherein senses electric current IIrradiate cable low;
3) to airframe appropriate point (common injection/outflow point pair:Head-vertical fin end, head-left/right horizontal tail end, machine
Head-left/right wingtip, wingtip-wingtip, keypoint part both sides etc.) injection low level current, it is sized, makes monitoring
To the sensing electric current I of the interconnecting cable of concern equipmentInject cable lowWith 1)~2) IIrradiate cable lowIt is identical, record this Injection Current INote low;
4) above step 1 is repeated)~3) to experiment full band scan measurement;
5) measurement data normalizes I to unit external irradiation fieldNote low/EOuter low;
6) by AVHRR NDVI data to desired aircraft exterior electromagnetic field level EMELOutsideCarry out linear extrapolation
INote high=EMELOutside×INote low/EOuter low
7) to airframe injection step 6) obtained high current INote high, realize that high level irradiation is replaced in electric current injection
Generation.Continue to sense electric current on the interconnecting cable of monitoring concern equipment, if also keeping linear ratio relation, confirm electromagnetism at the same time
The equivalence of environment.
4. aircraft exterior electromagnetic environment Safety Margin (low level coupled method) of example
Only illustrated by taking low level current scanning method LLSC as an example.Experiment process is:Configuration is suitably grounded by test specimen
Mode and earth point position (being carried out with actual installation state consistency or easy to test), first carry out low level irradiation, use strain relief clamp
Sensing electric current in pincers measurement interconnecting cable, obtains sensing the transfer function between electric current on irradiation field strength and interconnecting cable.Profit
With electric current is sensed in interconnecting cable under the high level irradiation field of the linear relationship extrapolation standard requirement between low and high level, that is, sense
Injected value of current.Finally keep constant by the earthing mode of test specimen and earth point position, will corresponding value electric current through cable clamp
Sensing injection is transmitted in interconnecting cable.Induction step is as follows:
1) with default low level EOuter lowElectromagnetic Field Irradiation is by test specimen;
2) detection current clamp is stuck in away from having at cabinet 50mm on interconnecting cable, measurement wherein senses electric current Ilow;
3) above step 1 is repeated)~2) to experiment full band scan measurement;
4) measurement data normalizes I to unit external irradiation fieldlow/EOuter low;
5) AVHRR NDVI data are subjected to linear extrapolation to the high level field strength of code requirement
Ihigh=EOuter high×Ilow/EOuter low
Electric current clamp are passed through to tested interconnecting cable and sense injection step 5) obtained high level energy, realize that electric current injects
To the replacement of high level irradiation, experiment is completed.
It is understood that for those of ordinary skills, can be with technique according to the invention scheme and its hair
Bright design is subject to equivalent substitution or change, and all these changes or replacement should all belong to the guarantor of appended claims of the invention
Protect scope.