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EMI Detectors: a key item to enhance safety of the systems?

As we are moving toward advance technologies like Industry 4.0 and autonomous systems, more and more issues related to electromagnetic disturbance are getting common. The EMI detector aims to solve the issue of EMI disturbance by detecting electromagnetic disturbances.

Have you ever wondered why your radio sometimes creates a sharp chirping sound when it is close to other electronic devices or why we are asked to turn off our mobile phones in an airplane during takeoff and landing? I don’t know about you, but I’ve always had a strong curiosity about this issue, especially when I was studying engineering. Although I hadn’t had a clear answer, I considered it was a signal transmission issue, but later on, reading about electromagnetic interference, I finally saw the light and I discovered most answers to my questions.

Actually, all electrical/electronic devices generate some kind of electromagnetic wave even when we don’t need them. However, reading that for the first time created doubts in my mind. Of course, we expect our mobile phone to send and transmit signals wirelessly through the air, but I wasn’t expecting this from other devices like simple motors and light bulbs. All electronic devices generate electromagnetic waves, wanted or unwanted as shown in figure below. Sometimes these waves are very useful and used for various applications, especially for the wireless transmission of a signal. Still, at other times, they can disturb a useful signal and in extreme cases, they can cause a fatal error. This is exactly the reason why we are asked to keep our phones off while taking off and landing.

Fig. 1: Different devices generate electromagnetic waves with different frequencies.

Many of us want to think about a quick solution whenever we find any problem. Same happened with me; the first idea in my mind was to solve this issue by designing all electrical/electronic devices in a way so they don’t generate electromagnetic waves, but this is practically not possible because of the inherent physical properties and the overall complexity. And moreover, some devices generate electromagnetic waves on purpose! A second option could be to develop other devices in a way that they keep working safely, even when electromagnetic waves are present. Many researchers are working on this topic, but it’s difficult to ensure protection for electromagnetic waves with all ranges of amplitude, frequency and phase, especially if we don’t know which electromagnetic waves are present.

In my PhD, I would like to tackle that last problem. Our idea is to develop EMI sensors or detectors. Then, if the EMI sensor detects the presence of electromagnetic disturbances that are beyond the normal immunity level of our system, our system could start working in safe, degraded mode, i.e. with a limited capability ensuring safe working and save the system from fatal errors.

Fig. 2: Initial design of the EMI detector for the data transmission lines.

More precisely, I am currently working on the idea of designing the EMI detector based on data transmission lines. This detector will generate a warning when EMI disturbs the transmitted signal and the system can retransmit the data or stop sending for some time while the EMI detector is generating the warning. My first detector prototypes are working very well when I am using two transmission, quite close to each other w.r.t wavelength of EMI , lines for the detection.. However, we have discovered some, albeit rare, situations in which the detector fails to detect the EMI. So I keep on working on the development of enhanced EMI detectors, which will detect EMI for all cases of a wired communication channel. I am excited and curious to find out something which will detect EMI in all cases, and if I do, I will share it with you.


About the Author: Hasan Habib

Hasan Habib has studied Electrical Engineering in his Master’s and also in Bachelors. He earned his Master’s degree with Distinction from Tampere University of Technology, where he carried out research in the field of RF sensors. During his Master’s research, he analyzed the relation between a wound’s state and the performance of RFID tags. The condition of a wound is proportional to the humidity level inside the bandage. The humidity level, in its turn, then affects the performance of RFID tags. Hence, a relation exists between the performance of RFID tags and a wound’s state. This phenomenon can help physicians to determine the condition of an injury without opening the bandage. After his Master’s, Hasan worked as a lecturer at National University of Sciences and Technology in Pakistan for three years.