In certain applications it is of highly importance to be able to identify unintentional pulsed interference sources. One reason is that this kind of interference can cause severe performance degradation of modern digital wireless communications. In this paper we show that pulsed interference sources can be identified by standard radiated emission measurements performed in the frequency domain.
Part 1: Conduction Paths . As briefly described in our introductory Article N°1 ( Issue #2-2015 of EE Magazine), ElectroMagnetic Interference is a Source/Coupling Paths/Victim situation, the basis for an overall understanding of EMI control in order to reach a satisfactory level of compatibility (EMC). We also said that reducing the interference at the source itself, or at the victim’s levels, were most of the time unpractical. Therefore, the only remaining area for action is in general the coupling path, which implies understanding the coupling mechanism.
Most designers . and installers of electrical equipment agree that shielded cables are a good way to achieve EMC. But many times I have seen big money thrown ”down the drain” because of overconfidence to the cable shield effects and ignorance of its proper use and design.
The number of mobile . subscriptions in the world is now as large as the number of people. To ensure future market growth, the mobile industry is working towards a vision that will make today’s use of mobile communications look like a mere starter.
Vi fortsätter . att betrakta vår figur: ”EMC från bricka till bricka” och går vidare till skyddsledare (PE). EMC måste tas om hand i alla delar, såväl på elektrisk som på mekanisk systemnivå, och på alla nivåer i en utrustning på ett systematisk och planerat sätt.
Robotic lawn movers, . small autonomous robots, are becoming more and more popular in the gardens. With a minimum effort the garden is kept tidy, without the noise and emissions from a petrol engine. But how about EMC-related emissions then? And will the lawn mower co-exist with other products?
En redaktörs reflektioner . Ibland kan EMC-frågor resultera i dilemman där motstående behov/krav behöver hanteras.
Preamble . As briefly described.in our introductory Article N°1 (Issue #2-2015 of EE Magazine), ElectroMagnetic Compatibility is both a functional neccessity – equipments must operate in their intended environment without being disturbed nor causing disturbances to other devices- and a society requirement: interfering with radio/TV broadcast, radio-communications and other RF services is illegal and punishable by laws. Since consumers cannot be easily prosecuted as guilty for using an equipment that is causing interference, the most efficient way of controlling this EMC situation is to apply stringent limits to manufacturers, such as the products they put on market will ”never” (exceptional situations accounted) cause interference.
EYE ON . It is relatively easy to achieve good attenuation (> 80 – 100 dB) of electromagnetic fields using a compact metal shield. In most practical cases, the shield is not complete, there are almost always openings, i.e. slots, windows and apertures. It is mainly these imperfections in the shield that determines the overall shielding effectiveness of the box.
The new version . of the JAS39 Gripen fighter is now a strong competitor in the fighter aircraft world market and the aircraft operates in several countries. A historical review of the early EMC work for the Gripen project may be of interest. The JAS 39 Gripen fighter aircraft project was outlined and presented in 1979-1981 by SAAB Military Aircraft & The Industry Group JAS also including the Ericsson Microwave Co. and Volvo Flygmotor. The development of the Gripen system and a production of 30 aircraft for the Swedish Air Force was decided by the Government in 1982. The decision was made after an intense debate in the media whether Sweden had the competence and capability to continue the independent fighter aircraft development although such projects had become extremely complex and costly.