The most widely used marking on products today is undoubtedly the CE logo. This sign of conformity with European Union norms in fact symbolizes the conformity of the product used with the relevant technical standards of the European Union. In terms of electrical and electronic devices, this marking means that the product is designed and manufactured according to the;

  • relevant EU standards
  • Electromagnetic Compatibility (EMC) Directive
  • Low Voltage Directive (LVD)

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The relevant EU standards are standards, which are specific to the product family, including functional tests that are sometimes required. However, more than the functional tests, the important issue for CE are the EMC and LVD standards, directed by the product family standard.

So, What about the directives?

Directives are the regulations announced by European Parliament and Council about a spesific topic, which contain the basic principles on that subject and all member states have to apply for the subject matter. As I mentioned above, there are two directives for CE in terms of electrical and electronic products, EMC and LVD. We have to remember the main principle that directives does not directly point out the tests to be applied, standards to be used or technical information etc…It sets the principles on the subject, explains the method of implementation, determines the responsibilities and describes the actions and penalties in case of non-compliance.

I have shared basic information about EMC in my previous articles. The European Union’s directive on general principles of EMC for CE marking is 2014/30 /EU at the time of writing this article (you can reach the original directive by clicking the link). It, in general, introduces the fundamental procedures for ensuring EMC requirements (the product is electromagnetically able to operate without disturbing its surroundings more than allowed and also not disturbed from the electromagnetic effects surrounding it). Therefore, it must be ensured that the relevant product conforms to EMC standards.

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The other essential requirement, as in EMC, is the compliance with the Low Voltage Directive (LVD). LVD is aiming to take measures to protect the health and safety of people, animals and goods in the market. The current EU directive is 2014/35/EU. We can say that the directive basically aims at enforcing related products safety standards.

Both directives share basic principles as I mentioned above. As a summary the most basic titles you will see in the content will be;

  • Requirements for placing the product on the market
  • Obligations of the manufacturer, representative, importers, distributors
  • Conformity assessment procedures, declarations
  • Non-compliance and penalties

There are two important points to be considered in CE marking;

First, preparation and storage of a Technical File containing reports showing the conformity of the product with the above directives, technical information about the product, explanatory documents etc. The other is to make the correct markings and to issue the necessary information on the product, its packaging or in the documents sent with the product. These details are set out in the contents or Annexes of the relevant directives. The most important issue, of course, is to take into account the latest version, the last one containing all the updates.


Do You Know That The Information In Your PC Is Spreading Around??

We know that electrical and electronic equipment may have intentionally or unintentionally electromagnetic energy radiation to their surroundings. Wireless transmitters, mobile phones, radars, detectors, wireless data transmission systems do voluntarily emit this energy. But it is not desirable for a computer, copier or projection device to emit electromagnetic energy around. As I mentioned in my previous article, TEMPEST is a term that refers to unintentional electromagnetic energy emissions caused from electrical and electronic equipment that process confidential information, and also a code name by U.S. to investigate, examine, and control such emissions.

Although it seems utopian, TEMPEST is quite an old method of intelligence. Once energy emitted from the electrical device is picked up by an antenna and receiver, it can be amplified and reprocessed, and sometimes image refined thus information leakage can be obtained. This method was brought to Turkey by a team that I myself was a member of, in 1990’s, a laboratory and technical infrastructure that can create, solve and test the TEMPEST Problem with completely national abilities was established and personnel were trained. The most striking point of the problem is that leakage from any information processing device can be obtained … information displayed on the computer screen, information read on the CD drive, information replicated on the copier, transmitted by fax, scanned on the scanner, printed on the printer … all the information processing equipment that can come into your mind, is a potential TEMPEST leak source.

Are you sure that your PC is safe with the precautions you had taken???

The simplest TEMPEST scenario is that; while you are writing a CONFIDENTIAL article in your computer, the exploiter is collecting the signals electromagnetically spreading from your screen and reconstructing it… just like collecting aerial broadcast information sent over kilometers and watching a TV programme in our living room… This process can be done surreptitiously upstairs, in the next building or in a panelvan with darkened glass parking in front of your office…just like you do not know who is watching your television broadcasts! This kind of leak is known as “radiated emissions leakage”. Another way of collecting information leaks beyond using an antenna is to penetrate the network which the information processing device is connected and reach to the information … Going through the same example, CONFIDENTIAL information in your computer can also be obtained by penetrating to the power network or internet network it is connected to, collecting the data by a monitoring probe, even from hundreds of meters away..! This method is known as “conducted emissions leakage”. Neither the update of the antivirus on your system, nor the power of your firewall means anything against TEMPEST, because if the information is open on your screen, the same information exists in the air and on your network, and therefore on the exploiters antenna and probe…

So, how can we become safe against TEMPEST Leaks??

Actually the risk is big, but some measures are quite easy. First, I must say that the only and safest measure of the leakage through the conducted emissions is the TEMPEST filtering to be done on the signal lines or the power lines. Filters are devices that prevent leaks out without affecting the operation of the device. Leaks caused by radiated emissions can be prevented by the use of special designed equipment. During my years at TÜBİTAK – UEKAE, I have directed National TEMPEST Filters, National TEMPEST Proof IT Equipment development projects. Today, thousands of devices we have developed are used in many critical govermental institutions and military areas. If you do not have a chance to use these special devices of high cost, you should pay attention to work in the special chambers with TEMPEST proof or having a large controlled zone by taking advantage of the principle that leakage signals decrease inversely with distance.


This article was published in periodical “Science and Technology to Everybody (Herkese Bilim Teknoloji)”, March 10th, 2017.

Electromagnetic Information Leaks: TEMPEST

The facilities we provide for living in the age of information technology are making information being processed with technological improvements more and more common every day. We are now able to carry information in discs about the size of a finger where not so much, back to 20 years ago, the same information was only be reached through hundreds of books on the shelves. All the libraries in the world are as close as our smartphone in our pocket …

A common feature of information-processing technologies is being under usage of electrical and electronic systems. This is, for sure, also the open door firstly applied by unauthorized persons who wish to access information. We know that electrical and electronic equipment voluntarily or unintentionally radiate some electromagnetic energy to their surroundings. The effect of this energy on the performance of the devices is observed under Electromagnetic Compatibility (EMC) subject. In terms of information security, there is a very serious threat in this case. TEMPEST is a code name that describes the work carried out to collect, examine, and reconstruct the information contained in electromagnetic energy emitted from electrical and electronic equipment. Although it seems like an abbreviation, TEMPEST is a name given by U.S. to the works in this subject. Yes, it may seem quite utopian at first sight, but TEMPEST has been used since the 1950s. The information is reconstructed by processing the electromagnetic leaks that propagate from the body of the information processing device to the air or to power network to which it is connected through its conductors. If this information is classified (confidential) information, of course the value is very high.

The first use of TEMPEST for intelligence purposes is that the British MI5 organization in the 1960s obtained information from France’s cryptographic communication in this way. However, during the Second World War, America had worked on this method and obtained a variety of information with similar principles, it can be understood from the documents that lost confidentiality today.

The first scientific and completely open work on TEMPEST was in 1985, an experiment and the paper explaining it by Wim Van Eck, a Dutch telecom researcher. The experiment  showed that a computer’s screen can be reconstructed from the electromagnetic emissions, meters away from the source.

So, what is the situation in Turkey ???

TEMPEST technology was brought to our country in the 1990s by a team that I was also a memeber of. In TÜBİTAK National Cryptology Institute, a TEMPEST laboratory was established and put in service for Turkish Armed Force and govermental bodies, by a protocol signed with the General Staff. So, although a little bit late compared to some leading states, the technology can still be pursued with national possibilities. The question that needs to be emphasized here is, what technologies do these advanced nations develop in our country’s today?

This article was published in periodical “Science and Technology to Everybody (Herkese Bilim Teknoloji)”, February 10, 2017.


Why Do We Have To Turn Off Our Mobile Phones in Aircrafts?


At these days of feeling as if naked at a deserted island when we don’t have our mobile phones with, it is for sure the most hated announcement of aircrafts hearing “Please turn your mobile phones off”. Like it or not we abide the  rule,but why is this measure necessary? Well, the answer to this question is right in it, this is a measure as most rough form..!

As I had shared in my previous articles, affecting other electronic devices with intentional or unintentional emissions from electronic devices is known as Electromagnetic Interference” (EMI), where operating without causing or being affected from interference is known as Electromagnetic Compatibility” (EMC). It is not difficult to find out that the main reason of the measure is this matter of fact..So, do the  mobile phones really cause harmful EMI? This question does not have clear and universally valid answer, it can be, or it is likely to be, because the matter depends on many factors; frequency of source, amplitude, environmental conditions, realization of the coupling requirements etc. All electronic devices of their nature, have electromagnetic emissions, more or less… It is unquestionably a fact that in case of this emissions build interference on the sensitive aircraft systems, it poses a vital risk!


Although the flight permissions are given after the aircraft passed the EMC tests and is certified to be in compliance with the standards, both as a system an also as equipment base, there is no guarantee that the test scenerio will exactly suit to the conditions of the real daily life! Think of it, notification of even a one percent margin of error is adequate for us to give up the use of the aircraft, taking the risk of this interference does not look very rational…

So, how big is the risk???

When using the mobile phone apart from its communication functions (as taking photo, playing music etc.) I can briefly state that the unintentional emissions are very small in amplitude. So the risk is “bigger than zero”, but clearly much too small. However, if the the subject is messaging or having a call, that requires wireless communication, we surely know that the intentional emissions of the device while trying to connect to the base station reach to high power levels, and also we know that those levels may be high enough to create risk to disturb the sensitive navigation systems of the aircraft. Although in today’s technology this risk is minimized with EMC precautions, it is still important  and can not be ignored…

Result; Stay away from mobile phones during flights! This will reduce the risk of danger, besides it also will lead to create an opportunity to socialize by contacting other passengers, face to face…



ESD Tests and ESD Precautions

In our daily life we often face to Electrostatic Discharge as the rapid transfer of static electricity on the human body to another object in the form of electric current. This discharge generally do not create a negative impact on human health. However, if the object that receives the current is a sensitive equipment or dangerous material, for example a flammable substance, then the result is not so much innocent.

Electrical and electronic devices may show susceptibility against this instant and rapid discharge. ESD in the order of kilovolts, can very easily affect circuits and devices running on the order of millivolts or volts. Therefore, especially the electronic devices restricted to some specific rules are expected to show an immunity at certain level against ESD. The most widely used standard in electrical and electronic equipment, is the European Union standardEN 61000-4-2.ESD Immunity Standardorganzied under Electromagnetic Compatibility (EMC) group mainlydescribes the basic pulse shape of ESD, voltage level to be applied, application method and the test setup simulating the ESD  resulting from of the operators of electrical and electronic equipment.

Waveform of an ESD Current (EN 61000-4-2)

Waveform of an ESD Current (EN 61000-4-2)

In the previous article entitled “What is ESD?” it was mentioned that ESD can occur by direct contact discharge and also by air discharge caused by breakdown of the air between two different potential objects approaching each other. Accordingly ESD tests of the standards explain to perform two seperate tests as contact (touching) or air (approaching) discharge. In these tests, ESD generator simulates the body of an operator charged with static electricity and the rounded tipof the generator represents operators finger.

Portable ESD Generator

Portable ESD Generator

Today, considering that many electronic devices have touch screens, it is more clear to understand the importance of ESD tests, especially for end users. So how does ESD affect the electronic device? In fact, the effect can manifest itself in several different ways. First, if we consider ESD as on the order of kilovolts therefore break the insulation of air, we would not be difficult to predict the mechanical and thermal effects. Especially, in the organizationsmanufacturing electronic device or a card, the components on the card may face physical and thermalstresses and burn out if an operator touches them without any measures. ESD, by generating an electromagnetic energy around the circuit may cause sensitive circuits and components to fail by electromagnetic effects. Besides all these, ESD causing unwanted currents to flow and voltage to be induced, may directly affect the sensitive circuits. This will result as breakdown of the components, reset of the device, display faulty values or maybe completely go off.

ESD precautions should be evaluated in two categories :

Precautions to be taken in the source device or operator: The main way to prevent ESD is to prevent static electricity forming. Antistatic materials may be preferred for this. For example, to cover the floor of the working area with material that does not cause static charging, in the same way operator shoes, garments, gloves made ​​of material which does not create static electricity is a solution. Furthermore, grounding the operator or the device potential to cause static electricity will prevent to be charged and lead the charge to flow to ground under control. The ESD wrist strap which is mandatory to wear while working is used for this purpose…

Precautions to be taken on the victim device or circuits: First, if possible, covering the vulnerable devices with antistatic material can be considered as a solution. However, it is unlikely to perform this practically.So, ESD resistant component selection, designing circuit according to the rules of EMC, efficient and proper grounding, designing filters to regions likely to face ESD or before sensitive components, and most common using varistors (MOV especially) that cuts the high voltage or current wave will lead to solutions in general.