layout, and relative spatial position between the sensor and the object under test, number of test frequency points, the operation time sequence of the object under test, limit of the test field strength, the susceptivity criteria and other important test elements, etc.;

(2)Conformity of the evaluation test items, the method and basis of EMC comprehensive evaluation, major problems and the verification results in tests, conclusions of tests in various phases, etc.

7.3 Evaluation Method

The evaluation method depends on the product’s characteristics that affect the EMC of the product. EMC evaluation can be conducted in hierarchy and by phase. “Hierarchy” means that the evaluation is performed on system, subsystem, and equipment. “By phases” means that the evaluation is performed throughout the principle design phase, the principle implementation phase, the system development and demonstration development phase, and the production and deployment phase.

7.3.1 The Hierarchical Evaluation Method

1. System-level EMC evaluation

System-level EMC is evaluated based on the electromagnetic environment, field coupling strength, inter-equipment interference strength, shielding effectiveness, harmonic characteristics, layout characteristics, antenna layout, cable, multi-equipment coupling, frequency allocation, and subsystem performance [75].

(1)Electromagnetic environment evaluation: Evaluate the impact of the electromagnetic environment inside and outside the system according to the environment of the intended mission;

(2)Field–circuit coupling strength evaluation: According to the electromagnetic environment of the system and the key circuits of each equipment, analyze the coupling relationship and their degree of influence of field–circuit, circuit— field, and circuit–circuit;

(3)Inter-equipment interference strength evaluation: Quantitative analyze the equipment that forms the interference, and evaluate the degree of the interference;

(4)Shielding effect evaluation: Evaluate the shielding effect of the key part of the equipment;

(5)Evaluation of resonance characteristics: evaluation of electromagnetic resonance characteristics of the key parts of the system;

(6)Evaluation of the layout characteristics: The system layout evaluation mainly includes evaluation of the equipment layout, antenna layout and cable layout;

(7)Antenna layout evaluation: Evaluate the antenna pattern after installation, isolation between antennas, etc.;

(8)Cable evaluation: Evaluate the radiated emission and conducted emission of the cables of high-power electrical equipment in the system, and evaluates the coupling of the cables of mission-critical equipment to EMI;

(9)Multi-equipment coupling evaluation: Based on the radiation emission and susceptibility characteristics of each equipment, evaluate the EMC of the subsystem or equipment set composed of multiple equipments;

(10)Frequency allocation evaluation: Evaluate the occupied frequency and frequency allocation of each subsystem and equipment in the system;

(11)Evaluation of subsystems/equipment’s performance degradation: After the equipment is interfered, quantitatively evaluate the degradation of performance indicators such as receiving sensitivity, decoding performance, and functional distance.

2.EMC evaluation of subsystems and equipment

Through the analysis and evaluation of PCB design, filter design, shielding design, cable and connector design, power supply characteristics, etc., we can predict the EMC of subsystems and equipment [76].

(1)PCB design: component selection, clock and bandwidth design, layering, functional partitioning, routing, impedance matching, decoupling and bypass, grounding, interface circuits, etc.;

(2)Filter design: filter design for power supply and signal;

(3)Shielding design: case shielding design, crystal shielding design, etc.;

(4)Cable and connector design: connector filtering, cable selection, cable termination, cable shielding design, etc.;

(5)Power supply characteristics: voltage and current characteristics, ripple and noise, temperature drift characteristics, overshoot amplitude of switching, etc.

The following should also be evaluated for the frequency using equipment:

(1)Emission characteristics: transmission power, harmonic rejection, and out-band emission attenuation;

(2)Receiving characteristics: reception sensitivity, out-band rejection, image suppression, and cross talk suppression.

7.3.2 Evaluation Method by Phase

Four phases, namely principle design phase, principle implementation phase, development and demonstration phase, and production and deployment phase are included.

1. Principle design phase

In the principle design phase, we mainly evaluate the EMC design schemes of systems, subsystems, and equipment.

(1)Analyze the dominant or implicit interference between the subsystems and equipment in the system and evaluate the system EMI prediction model.

(2)Evaluate the antenna layout scheme, focusing on the orientation pattern and antenna coupling after the antenna installation in the aircraft.

(3)Evaluate frequency allocation, equipment layout, and cable layout design.

(4)Analyze and evaluate the system shielding effectiveness, the electromagnetic environment inside and outside the system, the electromagnetic resonance characteristics of key parts of the system, and the performance degradation of the equipment subsystem.

(5)Evaluate the design measures of transmission power, harmonic rejection, outband emission attenuation, receiving sensitivity, out-band receiving rejection, image rejection, cross talk suppression, shielding, grounding, and power supply filtering.

(6)Analyze the board radiation, line cross talk, signal integrity and other characteristics.

The main supporting documents from the research institute in this phase are:

(1)“EMC Management Requirements” of systems, subsystems, and equipment;

(2)“EMC prediction and evaluation report in principle design phase” of systems, subsystems, equipment;

(3)“EMC quality evaluation report in principle design phase” of systems, subsystems, and equipment;

(4)“Summary report on EMC work in demonstration phase” of systems, subsystems, and equipment;

(5)Other reports related to EMC, such as quality analysis reports, standardization reports.

Based on the above-supporting documents, the EMC management office will then review the following transition documents:

(1)“EMC outline”;

(2)“EMC control plan”;

(3)“EMC test plan”;

(4)“EMC design plan in principle design phase” for systems, subsystems, and equipment;

(5)“Overall technical requirements for EMC” for systems, subsystems, and equipment.

2. Principle implementation phase of subsystems and equipment

(1)Evaluate the EMC design scheme in the principle implementation phase, check whether the evaluation result of the principle design phase is implemented in the principle implementation design, and determine the rationality of the design scheme.

(2)Through the EMC test, evaluate the implementation of the EMC design for subsystems and equipment in principle implementation phase.

(3)Evaluate the EMC of the prototype in principle implementation phase by analyzing the electromagnetic emission and susceptive characteristics of the subsystem and equipment.

(4)Evaluate system EMC performance by predicting and analyzing factors including the electromagnetic environment of the system, the strength of the field coupling, the interference intensity between the equipment, the influence of system EMC oversize.

(5)Evaluate the EMC design indicators of the optimized subsystems and equipment.

(6)Evaluate the improved system integration design scheme by analyzing the optimized system-level EMI prediction model.

The main supporting documents from the research institute in this phase are:

(1)“Summary report on EMC work in principle design phase”;

(2)“EMC prediction and evaluation report of principle implementation phase”;

(3)“Evaluation report on EMC quality of principle implementation phase”;

(4)“EMC test outline of principle implementation phase”;

(5)“EMC test result of principle implementation phase”;

(6)Other EMC-related reports, such as quality analysis reports, standardization reports.

Based on the above-supporting documents, the EMC management office will then review the following transition documents:

(1)“EMC design scheme of principle implementation phase”;

(2)“Summary report on EMC work of principle implementation phase”.

3. System development and demonstration phase of subsystems/equipment

(1)Evaluate the EMC design scheme of the system development and demonstration phase. The major evaluation items include whether the EMC evaluation results of subsystems/equipment of principle implementation phase have been reflected in the design of system development and demonstration phase; and whether the method of the EMC process control in the system development and demonstration phase is reasonable.

(2)Through the EMC test, evaluate the implementation of EMC design on subsystems/equipment in system development and demonstration phase.

(3)By analyzing the effect of EMI suppression measures of the prototype in system development and demonstration phase, evaluate the EMC of the system and equipment in system development and demonstration phase.

(4)Evaluate system EMC through the prediction and analysis of the influence from subsystems/equipment’s EMC oversize on the system performance, combined with the EMC evaluation results of the subsystems and equipment in system development and demonstration phase.

(5)Through system EMC test, evaluate system EMC and optimize the EMC design.

The major supporting documents from the research organization in this phase are as follows:

(1)“Summary report on EMC work in principle implementation phase”;

(2)“EMC prediction and evaluation report in system development and demonstration phase”;

(3)“EMC quality evaluation report in system development and demonstration phase”;

(4)“EMC test outline in system development and demonstration phase”;

(5)“EMC test result system development and demonstration phase”;

(6)“EMC joint test report”;

(7)“EMC process control requirements”;

(8)“Hazard analysis report of excess EMC”;

(9)Other reports related to EMC, such as quality analysis reports, standardization reports.

Based on the above-supporting documents, the EMC management office will then review the following transition documents:

(1)“EMC design scheme of system development and demonstration phase”;

(2)“Summary report on EMC work of system development and demonstration phase.”

4. Stereotype phase

In the production and deployment (verification) phase as well as the application and maintenance phase, we need to evaluate the EMC of the systems, subsystems, and equipment.

(1)Evaluate the EMC of subsystems and equipment through EMC stereotype (verification) test of subsystems and equipment.

(2)Evaluate the system EMC through the system EMC stereotype test.

The major supporting documents input by the research organization in this phase are:

(1)“Summary report on EMC work in the system development and demonstration phase” of subsystems and equipment;

(2)“Summary report on EMC work of engineering development phase” of system;

(3)“EMC quality evaluation report in the production and deployment phase” of system, subsystem, equipment.

Based on the above-supporting documents, the EMC management office will then review the following transition documents

(1)“EMC stereotype (verification) test outline” of subsystems and equipment;

(2)“EMC stereotype test outline” of the system.

7.3.3 Specific Requirement for Documents

1. EMC outline

The EMC outline is used to specify the working requirements and methods for EMC organization, management, design, prediction, evaluation, verification, process control, delivery, training, etc. It is a general guide for EMC development of information systems. It is also the basis for developing EMC work plans and other documents.

The purpose of the EMC outline is to enable managers and engineers to treat EMC as a basic performance requirement throughout the entire life cycle of an information system and meet the EMC requirements.

The EMC outline should be developed at the beginning of the principle design phase. It mainly includes the following aspects:

(1)EMC standards, regulations the system follows and how they have been tailored;

(2)EMC organization and its duty, authority, division of labor, and scope of work;

(3)The objectives, contents, requirements, and methods of EMC management in the development process;

(4)EMC work plan;

(5)EMC training, design and verification, prediction and analysis, evaluation, process control, assessment requirements and methods.

2. EMC control plan

The EMC control plan is formulated to fully explain the planning and technical measures related to EMC, and establish the basis for EMC work in the development process to ensure that the EMC requirements specified in the contract are met.

The contents majorly include management, spectrum protection, design of EMI prevention structure, electronic/electrical wiring design, EMC circuit design. In the actual EMC design, the EMC of the system, subsystem, and equipment is controlled by quantitative design.

3. EMC test plan

To ensure a good EMC performance for equipment, a series of EMC tests are required during the development process. In order to coordinate the EMC with other aspects in engineering development, and determine the content, type, scheme and progress

of the EMC test, a special EMC test plan needs to be formulated and submitted to the management office in a timely manner.

The test plan mainly includes the scope of application, references, product technical status description, test items and requirements (including system-level test and equipment/subsystem-level test), test schedule, test facilities and equipment, budget, possible problems and solutions and test plan improvement measures.

4. EMC design scheme

EMC design mainly includes the scope of application, reference, electromagnetic environment, EMC requirements, EMC design guidelines, EMC design schemes, EMC prediction and analysis, and EMC test verification.

EMC design scheme includes subsystem or equipment key categories, performance degradation criteria, safety factors, interference and susceptibility control, wire and cable wiring, power, spikes, lapping and grounding, lightning protection, static protection, personnel protection, damage to flammable and explosive devices, design for external environment adaptation, design and application of devices.

EMC prediction and analysis mainly include internal system, between subsystems/equipment; between systems; among system, subsystem, equipment and electromagnetic environment; spectrum utilization and spectrum allocation.

5. Overall EMC technical requirement

The overall EMC technical requirements are used to stipulate the EMC technical indicators that the system and its subsystems and equipment should meet. The requirement should include a clear specification for the technical measures and test items to be carried out in order to meet the EMC requirements in the development process. The overall EMC technical requirements include the followings:

(1)Susceptive criteria when systems, subsystems, and equipment are subjected to EMI;

(2)EMC categories of subsystems and equipment, and the safety margins they should have;

(3)Test items of subsystems and equipment and the corresponding limit values. Description of the tailoring of the existing regulation should be included;

(4)Power supply characteristic requirements of systems, subsystems, and equipment;

(5)System cable selection, categorized laying, and wiring specifications;

(6)Design specifications for lap joint and grounding of systems, subsystems and equipment;

(7)Filter selection and installation specifications for subsystems and equipment;

(8)The specification of the crystal oscillator frequency of the clock circuit of the subsystem and equipment;

(9)Board layout and wiring specifications for subsystems and equipment;

(10)The digital circuit pulse rising edge specification of subsystems and equipment;

(11)Case structure and shielding design specifications for systems, subsystems, and equipment;

(12)Lightning and electrostatic protection class and measures for systems, subsystems, and equipment;

(13)Spurious rejection, harmonic rejection, cross talk rejection, and adaptability of external RF environment of RF equipment;

(14)Special tests and methods for systems, subsystems, and equipment.

The major supporting documents are:

(1)“EMC management requirements” of systems, subsystems, equipment;

(2)“EMC prediction and evaluation report of the principle design phase” of systems, subsystems, and equipment;

(3)“EMC quality evaluation report of the principle design phase” of systems, subsystems, and equipment;

(4)“Summary report on EMC work of the demonstration phase” of systems, subsystems, and equipment.

6. EMC management requirement

EMC management requirements are formulated according to the development requirements of systems, subsystems, and equipment.

7. Prediction and analysis report

EMC prediction and analysis should be performed to determine the scope and extent of the EMC problem of the engineering system, such that the project management personnel and engineers, as well as the production and maintenance personnel, will have an expectation or even discover the potential EMC problems in advance. EMC prediction and analysis provide basis for decision making for engineering development.

The content of prediction and analysis is as follows:

(1)Scheme demonstration and preliminary design phase. This phase is to assist the determination of the main characteristics and technical conditions of the system, such as modulation type, data rate, information bandwidth, transmission power, receiving sensitivity, antenna gain, and parasitic signal rejection. The general contents to be predicted and analyzed are:

electromagnetic problems between internal equipment and components of

the system;

electromagnetic problems between systems and subsystems;

electromagnetic problems among systems or equipment, components, and electromagnetic environment;

spectrum utilization and frequency configuration issues.

(2)Development and trial production phase. In this phase, it is necessary to determine the specific performance parameters and functional level components of the equipment, such as amplifiers, mixers, filters, modulators, detectors, display

or readout devices, power supplies. Common contents of prediction and analysis are:

Electromagnetic problems caused by external electromagnetic signals coupling to different devices and components in the system;

Cable coupling;Case coupling;

Case shielding effectiveness.

(3)Production, deployment, and application phase. In this stage, the electromagnetic control is analyzed and solved by frequency management and electromagnetic control in the time domain and airspace. The prediction and analysis contents generally include

Site effect;

Frequency management;

Effective radiated power limitation;Coverage of antenna beam;

System EMC comprehensive analysis.

8.Quality evaluation report

The evaluation report mainly includes the following contents:

(1)The basic conditions of the product such as product name, research organization, development phase, development type, product function, product composition, and principle;

(2)System EMC such as electromagnetic environment, shielding effectiveness, resonance characteristics, layout characteristics, and frequency allocation.

(3)Installation characteristics of subsystems and equipment:

Installation environment: Specify the installation position of the product. For

equipment with antennas, there should be a clear description of the installation location for the antennas and whether there are special requirements of electromagnetic field environment where the antennas are installed;

Operating power: Identify the transmission power of the transmitter, receiver sensitivity, voltage and current usage of nonRF transceivers, etc.;

Operating frequency: Specify frequency information including the local oscillator, IF, RF on the transmitting link and receiving link of the product;

Interfered object: Identify other products that may be interfered by this product;

Interfering object: Identify other products that may interfere with this product.

(4)EMC requirements for the product:

Standard items: Select the test items according to the test requirements of existing regulations combined with the characteristics of the systems, subsystems, and equipment;

Description of the tailoring: Explain the tailoring of existing regulations by the product;

Other explanations: In addition to the existing regulations, if there is any other EMC test needed due to the product’s own requirement, the research organization should list the additional test requirement.

(5)Existing EMC problems in products: Identify the EMC problems found in product testing. With the existing problems, we either keep the product as it is or solves the EMC problems that have occurred before;

(6)Product EMC design evaluation: Evaluate all EMC design of the products, including spectrum, structure, PCB, grounding, shielding, filter, cable interface, power supply;

(7)Test condition of the product: Identify the test organization, test items that the product fails and describe the test condition;

(8)Result of product improvement: Provide the system EMC performance after improvement;

(9)Quality management: Including the supervision and inspection of EMC issues by the quality system, and whether the technical quality problems have been solved;

(10)Product EMC compliance analysis.

9.Quality analysis report

The quality analysis report mainly includes introduction to the development process, how well the technical indicators are in line with the mission specifications, product technical status compliance, implementation of quality assurance outline; how well the product performance is in line with the technical indicators, product quality, quality issues; and whether the problems have been solved, special review, and product quality conclusions. The items are described in detail as following:

The implementation of the quality assurance outline includes outline preparation, work principles and quality objectives, management responsibilities, documents and records control, quality information management, technical status management, personnel training and qualification assessment, customer communication, quality control of design process, test control, procurement quality control, trial and production process quality control and standardization reports.

The execution of quality problem solving includes problem description, cause analysis, corrective action and final check of whether the problem has been solved.

10. EMC test outline

The main contents of the EMC test outline include scope of application, basis for outline, purpose of the test, quantity and technical status of the test object, accompanying test object and supporting equipment, test items, test contents, test methods,

number of major test equipment and key parameters, data processing principles and qualification criteria, test organization, institutes that participate the test and task division, test schedule, test security and requirements.

11. EMC test report

The main contents of the EMC test report include test overview, test items, steps and methods, test data, main technical problems and solutions in the test, test results, conclusions, problems and suggestions for improvement, test photos, real-time audio, and video data of the main test items.

12. EMC comprehensive evaluation report

The main contents of the EMC comprehensive evaluation report include electromagnetic environmental conditions, EMC requirements, EMC design guidelines, EMC design schemes, EMC test contents and results, EMC problems and solutions, and the remaining problems and the suggested solutions.

Among them, the EMC design scheme mainly includes key categories of subsystems and equipment, performance degradation criteria, safety factor, interference and susceptibility control, wire and cable wiring, power supply, spike signal, lap and grounding, lightning protection, static protection, personnel safety protection, flammable and explosive materials and equipment hazards, external electromagnetic environment, and suppression measures taken.

EMC problems and solutions mainly include phenomena, problem causes, solutions, and verification.

7.3.4 Specific Evaluation Methods

The analytic hierarchy process is used to classify the EMC requirements involved in the evaluation and determine the weights. Then, according to the interference correlation relationship and the interference correlation matrix, each scoring criteria is determined, and finally, the EMC factors during product development are rated by experts.

1. Determination of the weight value

(1) Cluster analysis by existing standards

According to the existing standards, the key categories of subsystems and equipment stipulate that all subsystems and equipment installed in the system or related to the system should be classified as one of the key EMC categories. These divisions are based on the effects of EMI, failure rates, or degradation procedures for assigned tasks. There are the following three categories.

(1)Class I: This type of EMC problem may result in shortened life, damage to the vehicle, disruption of tasks, costly transmission delays, or unacceptable system efficiency degradation.

(2)Class II: This type of EMC problem may cause malfunction of vehicle, decrease of system efficiency, such that the task cannot be completed.

(3)Class III: This type of EMC problem may cause noise, slight error, or performance degradation, but will not reduce the effectiveness of the system.

According to the classification of the safety equipment in the existing regulations, all subsystems and equipment are first clustered according to I, II, and III classes.

(2) Constructing weight indicators using hierarchical analysis process.

When the analytic hierarchy process is used to determine the weight of the subsystem and equipment, it is necessary to comprehensively consider various factors, including the probability of problems in the development of information system and equipment in the past, the degree of influence on other equipment and on the system. The metrics of the analytic hierarchy process indicators are shown in Table 7.1.

2. Determine the evaluation criteria

(1) Determine the limit

According to the interference correlation relationship and the interference correlation matrix, we can determine the radiation and susceptibility related limits of each subsystem and equipment. The main limits are as follows:

(1)Susceptibility threshold: refers to the signal level that causes the test object to exhibit a minimum discernible undesired response;

(2)Susceptibility threshold: the interference threshold level at which the system cannot work normally;

(3)Failure interference level: the level of EMI that the system is not allowed to accept, in other words, the interference level that causes permanent failure or permanent malfunction of the receiver;

(4)Allowed interference: the maximum interference that the system allows;

(5)EMI emission value: EMI (including radiation emission and conducted emission) brought to the surrounding environment when the system with electromagnetic transmission is allowed to work, the EMI value must not affect the operation condition of surrounding subsystems;

(6)Safety margin: the difference between the relative threshold and the actual interference signal level in the environment.

(2) Optimization limits

The limit value is optimized through the comparison with the test data, and the system’s feasibility, cost-effectiveness, and other factors.

3. Expert scoring system

The expert scoring system is used to evaluate the EMC of the system, subsystems and equipment, and the evaluation results are comprehensively processed [77].

The expert scoring comes in two levels: Firstly, according to whether the planned EMC work has been carried out, a 0–1 score will be filled by computer, that is, 1 point for work being carried out, and 0 point for not carried out. The work carried out is then evaluated in detail from a technical level and scored by experts.