Assessment and control of spacecraft electromagnetic interference

Design criteria are presented to provide guidance in assessing electromagnetic interference from onboard sources and establishing requisite control in spacecraft design, development, and testing. A comprehensive state-of-the-art review is given which covers flight experience, sources and transmission of electromagnetic interference, susceptible equipment, design procedure, control techniques, and test methods

Unconsidered but influencing interference in unmanned aerial vehicle cabling system

The increasing complexity of electrical and electronic systems in unmanned aerial vehicles (UAVs) has raised concerns regarding unwanted electromagnetic interference (EMI) due to limited compartment space. Recent studies have highlighted the UAV cabling as the primary pathway for interference. This paper presents a novel approach to investigating the effects of interference power, polarization angle, and distance from the interference source on EMI in UAV cable systems. Measurements and simulations were performed to analyze the influence of these factors on the radiation received by the cable. A linear dipole antenna, operating at a frequency of 905 MHz, served as the radiation source, while a single wire cable pair terminated with a 50-ohm resistor was employed as the victim. The findings reveal that the power transmitted by the source, the distance between the cable and the source, and the polarization angle have a significant impact on the electromagnetic interference received by the cable. Notably, a perpendicular orientation of the cable to the interference source (antenna) in the far-field yielded a reduction of up to 15 dBm in EMI. The results underscore the necessity for more sophisticated models and comprehensive measurements to fully comprehend the diverse factors affecting polarization losses in practical scenarios

Multimission Aircraft Design Study: Electromagnetic Compatibility

The multi-mission aircraft (MMA) technical feasibility study looked at the replacement of the aging fleet of C-135 and C-130 theater based command & control (C2) and intelligence, surveillance and reconnaissance (ISR) fleet. It is proposed that the MMA be out-fitted to combine some or all the functions of existing AWACS, JSTARS, RIVET JOINT, COMPASS CALL, and ABC CC platforms. It would also have links to other manned or unmanned ISR aircraft, as well as satellites. The objective of the proposed design study is to examine the technical risks involved in combining multiple functions onto one aircraft that currently reside on separate aircraft. This thesis specifically focused on the risks that are due to electromagnetic interference between transmitters and interference between active and passive sensors. Two architectures were examined: one tail number (OTN) and different tail number (DTN). The OTN architecture was found to be incompatible due to interference between the air moving target indicator transmit and high band receive functions, whereas, the DTN was found to be compatible for all variant architectures

Probabilistic approach to EMP assessment

The development of nuclear EMP hardness requirements must account for uncertainties in the environment, in interaction and coupling, and in the susceptibility of subsystems and components. Typical uncertainties of the last two kinds are briefly summarized, and an assessment methodology is outlined, based on a probabilistic approach that encompasses the basic concepts of reliability. It is suggested that statements of survivability be made compatible with system reliability. Validation of the approach taken for simple antenna/circuit systems is performed with experiments and calculations that involve a Transient Electromagnetic Range, numerical antenna modeling, separate device failure data, and a failure analysis computer program

High-Density Digital Links: Optimization of Signal Integrity and Noise Performance of the High-Density Digital Links of the ATLAS-TRT Readout System

The Transition Radiation Tracker (TRT) is a sub detector of the particle detector ATLAS (A Toroidal LHC ApparatuS). About 420,000 detecting elements are distributed over 22 m3. They produce each second approximately 20 Tbit of data which has to be transferred from the front-end electronics inside the detector to the back-end electronics outside the detector for further processing. The task of this thesis is to guarantee the integrity of the signals and the electromagnetic compatibility inside the TRT as well as to the aggressive surroundings. The electromagnetic environment of particle detectors in high-energy physics adds special constraints to the high data rates and the high complexity: high sensibility of the detecting elements and their pre amplifiers, confined space, limited material budget, a radioactive environment, and high static magnetic fields. Thus many industrial standard measures have to be abandoned. Special design is essential to compensate this disadvantage

Analytical and experimental study of the electric shielding effectiveness of a metallic enclosure for off-centred apertures

An electromagnetic shielding is frequently used to protect against external fields and leakage from electronic products to meet the electromagnetic compatibility (EMC) requirement. However, it is a great challenge to design a practical electromagnetic shield because its integrity is often compromised by apertures and slots used to accommodate ventilation or access to interior components. Such openings allow exterior fields to be coupled onto printed circuit boards (PCBs), thus inducing current and voltage on interior conductors. This phenomenon will degrade the shielding effectiveness (SE) of the enclosure. This research is performed to investigate the effects of apertures on the SE of a rectangular metallic enclosure for off-centred apertures by using an analytical formulation and experimental study. The theories developed by other researchers have been extended to take into account the contribution of higher order modes and off-centred apertures in the enclosure. The electric shielding effectiveness, Se were calculated as a function of frequency, enclosure dimensions, aperture dimensions, aperture locations and various observation points by employing a transmission line equivalent circuit approach. The extended formulation applies only to rectangular enclosures with rectangular apertures, but simple modifications were included to account for square, circular, multiple apertures and the effect of the enclosure contents. Generally, the analytical results of the Se are in good agreement with measurement results which were conducted in a Gigahertz Transverse Electromagnetic (GTEM) cell in the range of frequency from 10 MHz to 1 GHz. As an example, the Se at 600 MHz using analytical formulation has 92% similarity compared to measurement results. It was also found out that by taking into account five modes above the TEio will contribute an additional 35 dB to the Se at 800 MHz. This indicates the significance of multimode in determining Se for enclosure with off-centred aperture. In addition, the results agree with present understanding on the dependence of SE on aperture sizes, aperture shapes, aperture locations and effect of electromagnetic losses in the enclosure. The reduction of Se by about 9.5 dB due to multiple apertures indicated by 20 log n where n is the number of apertures was also successfully endorsed in this work. The findings generated from this research work can be used as design rules by designers of practical shielded enclosures. Future works can be carried out to incorporate enclosures of various shapes and sizes at frequencies greater than 1 GHz

REDUCTION OF SUSCEPTIBILITY FROM ELECTROMAGNETIC INTERFERENCE IN SENSORLESS FOC OF IPMSM

This paper presents main problems of practical implementation of Field Oriented Control (FOC) developed for an Interior Permanent Magnet Synchronous Motor (IPMSM). The main sources of Electromagnetic Interferences (EMI) noises are discussed and practical aspects when a position sensor is used are presented. The control system is based on the DSP processing unit, together with inverter and encoder. The main problem addressed in this paper is reduction of vibrations in torque and speed response in a real system by re-placing a hardware device of control system very susceptible to EMI noises, like encoder, with a soft block in control unit like Sliding Mode Observer, less sensitive to EMI. The experimental results with this control structure show considerable ripple reduction at steady state in torque, speed and current, as a consequence of reduction of sensitivity to EMI noises

Design for Electromagnetic Compatibility--In a Nutshell

This open access book provides practicing electrical engineers and students a practical – and mathematically sound – introduction to the topic of electromagnetic compatibility (EMC). The author enables readers to understand better how to overcome commonly failed EMC tests for radiated emission, radiated immunity, and electrostatic discharge (ESD), while providing concrete EMC design guidelines. The book also presents an overview of EMC standards and regulations and how to test for a global market access

Space Station Freedom data management system growth and evolution report

The Information Sciences Division at the NASA Ames Research Center has completed a 6-month study of portions of the Space Station Freedom Data Management System (DMS). This study looked at the present capabilities and future growth potential of the DMS, and the results are documented in this report. Issues have been raised that were discussed with the appropriate Johnson Space Center (JSC) management and Work Package-2 contractor organizations. Areas requiring additional study have been identified and suggestions for long-term upgrades have been proposed. This activity has allowed the Ames personnel to develop a rapport with the JSC civil service and contractor teams that does permit an independent check and balance technique for the DMS

Sortie laboratory, phase B technical summary

The design and operational requirements which evolved from Sortie Lab (SL) analysis are summarized. A source of requirements for systems is given along with experimental support for the SL, baseline. Basic design data covered include: configuration definition, mission analysis, experimental integration, safety, and logistics. A technical summary outlines characteristics which reflect the influence of the growth in SL capability and the results of the mission and operational analysis. Each of the selected areas is described in terms of objectives, equipment, operational concept, and support requirements