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The Sensitivity Of Phones or Harmful Myth About Those

Together with occurrence of first mobile phones, already analog standards, among users began popular to discuss, as far as sensitivity of this or that model is great. Under this term was taken literally how well worked the device in conditions of weak signal, for example, in cellars or on border of a cover zone. Accordingly to a choice of phone people tried to be guided by models which had the best features, providing communication even there, where other models gave in. Really, the sensitivity in narrow-minded concept of this word for analog standards plays a role, as quality of communication depends on many factors, in particular capacities of the phone transmitter, a level of the battery charge and characteristics of the category, weather in the street, and others. Actually and there was a stereotype which prevails now over consciousness of the ordinary consumer.

Analog standards of communication were superseded in our country (Russia) by GSM, i.e. with the digital standard, but conversations on "sensitivity" of the devices have not ceased. Let's try to take up together of what there are similar discussions and what reasons can result subscribers of various networks confirming «various sensitivity» of the devices. As background it would be desirable to note, that, as well as any other standard, GSM has undergone some phases of development. At the first stage of becoming, despite of the existing parameters described in the standard for terminals, not all the manufacturers kept them. The reason was that recustomizing of the manufacture was required, creation of the new element base and training of the engineers to work with it. Many principles of the terminals construction have been taken from experience of the analog devices creation. But half of the problem consists in it only, the other half was predicted and expected. At the moment of occurrence the GSM-networks had the worse covering, rather than already existing analog networks, for example, NMT or AMPS. As result subscribers of such networks received for comparable money, or even big, the worst service, as their phones was not working everywhere.

The most obvious and simple way of this question decision, besides expansion of operator's cover zone, began increasing in capacity of the transmitter fixed in the user's terminal, i.e. usual phone. It resulted in the raised power consumption; the phone worked one, two days at heavy use. Users of that time frequently bragged as far as powerful were their devices, how many pickups they caused in audio equipment or monitors at incoming call. Frequently, speakers started to rattle even in the case when the person was in pair meters from them. Each manufacturer independently defined what capacity transmitter to fix in this or that model, frequently the decision was accepted on the basis of the operator's requests which ordered a large batch of devices. It is necessary to be stipulated, that for that moment there were restrictions on the maximal capacity of terminals, but they were rather liberal for manufacturers. As indicative example that fact can serve, that one of Motorola models worked in the Moscow underground in 1996, at stations with small bedding depth. By that moment in the underground it has not been established base stations of operators, the phone accepted signal from ground surface.

High capacity of the transmitter in GSM-terminals besides steady communication resulted in influence on organism, and harmlessness or perniciousness of such influence have not been proved. Nevertheless, the first wave of GSM-phones fell, operators had time to provide comprehensible covering, both in city boundaries and behind it, and they turn into competitors with analog networks. Need for capacity overstating of transmitters has disappeared itself. Since this moment to compare the sensitivity of GSM standard devices became useless as began the rough process of standardization.

On my memoirs from the end of 1997, the beginning of 1998 began to appear phones of the new formation, they differed the increased operating time in standby mode, but had the same accumulators as their predecessors. It is possible to explain the increased operating time the improved covering in networks of operators, work in two ranges (GSM900/1800), and also gradual decrease of transmitters’ capacity. To the middle of 1999 the process has taken the avalanche character, and the majority of manufacturers inside the products model line have reduced capacity of terminals to the general denominator.

The other reason that induced them to such actions was the interest of consumers to influence of the radiation on organism, to occurrence of such size as SAR (Specific Absorption Rates) which is directly connected with capacity of the device became induced. SAR is a level of radiation (issue) in watts on kg of tissue (Wt/kg). Simply speaking, SAR shows how much radiation is absorbed by body. Till 2001 the SAR size fixed legislatively, was rather big - in the Great Britain, for example, the top threshold was equal to 10 Wt/kg. In reality the phones radiated for that moment less radiation, the acceptance of more rigid norms did not conduct to change in the phones construction. Therefore the manufacturers have helped to generate such norms with pleasure, in this case it could not be the claims to them from the direction of consumers, they carried out all the governments’ instructions of various countries. Having created positive image to themselves, nevertheless, the companies have helped involuntarily to organize really working measures of radiation which bears the fruits already now. Any manufacturer cannot sell mobile phone in the USA or Europe if the level of radiation is not specified in the instruction. In Europe maximum SAR level is equal to 2 Wt/kg (at measurement on 10 grams of tissue), Australia and the USA - 1,6 Wt/kg (at measurement on 1 gram of tissue).

The less is the SAR value, the apriori the phone is more safely, though his influence on the organism has not been proved. Manufacturers have joined in race for the least SAR parameters; within the next years many countries have obliged them to specify the corresponding SAR value in phone's instruction. From the end of 2002, the beginning of 2003 many western consumers start to be guided by SAR value at a choice of the device, pushing manufacturers to even big decrease of this size.

Within the framework of this material we are interested in decrease of capacity of the devices which has taken place. Moreover, last tendencies are those, that manufacturers build the model line on the basis of the same technological platform. As example, Nokia 6610/6100/7210/7250/5100 phones can serve, all of them have an identical "hardware" stuffing, and also the software responsible for communication (this hardware-software complex has received the name a platform 40). To compare "sensitivity" of these devices is silly; it will be identical or very close. Other manufacturers also reduce the costs and build the model line on one platform that allows its standardizing.

The close reader, who has read up the material up to this place, has already a set of questions. He can tell, that all this is the theory, and in practice all phones behave differently, ones work better, and the others work worse. Let's try to understand, in what can be a problem here.

First, it is necessary to understand that each phone has the software responsible for work with network, it directly influences adjustments of a send-receive part of phones. There are factory adjustments, they, as a rule, are optimal, that provides steady work of phone in various networks. In conditions of the service centers at change of the software or without those, phone can be adjusted for work in a concrete network; it receives optimum adjustments under this network. In most cases this procedure is unnecessary as factory adjustments approach to 99 of 100 networks, the device perfectly works in them.

The problem can arise, if someone has independently rummaged in the software of the phone, without having the necessary tools, skills and knowledge. In this case the device can work, somehow, for example, constantly to lose the network, to break off conversations, in the loud speaker you can hear a constant echo and etc. Such problems are occasionally observed in unlocked devices, unofficially delivered and initially intended for work in the certain networks, for example, Orange, Vodafone. Thus the devices which have not undergone updating perfectly work in various networks.

Other interesting moment is connected with prototypes of models which have not acted yet in the wide sale. Any company prior to the beginning of the official sales makes a few thousand engineering samples which serve for natural tests, testing of the software. Sometimes such phones get in sale, but sellers do not mention that they are stolen, and second, frequently work unstable, not providing steady communication. It is a problem of prototypes, and not completely serial samples. The SAR value for such devices frequently exceeds all conceivable norms. For the sake of justice, it is necessary to tell, that the problem with prototypes is not so is wide, as there are a few of them in the market, it's more likely individual sales.

Example of other sort. Your friends and you have gone to a small restaurant which is in the cellar, phones work for them, but not for you. The first explanation can be the most simple, you have different operators so one has nearby base station, and your operator does not. Thus it is necessary to remember that to judge the quality of communication by quantity of "sticks" on the screen is impossible, different phone models have various speed of updating this information. So, you can go down in the underground where there is no network, and the phone will still show its presence. Attempt to call naturally will give nothing. As the most real check attempt to call can serve and it only.

It sounds enough strangely, but work in a network can depend on a charge of your accumulator so in conditions of a steady signal you can accept calls, to call. In conditions of unstable communication when peak loading on the phones transmitter is required, the accumulator can not provide a necessary pressure (it concerns not completely new devices, and more likely that are in use more than one and a half two years).

As other reason for deterioration of reception the cover of phone can serve. So, some Chinese models have opposite to the aerial of the device (especially if it is internal) every possible metal rivets and holders. They, certainly, worsen quality of communication, the phone increases capacity to provide steady connection.

If you cover during conversation the aerial with a hand capacity also increases as there is reduction of signal. Taking into account, that phones became small in the sizes, to cover the aerial with hand is very easily. It changes sensitivity of the device a minimum on 4-5 dB. And as show tests of all modern phones distinction between them just and are stacked in those 4-5 dB. In turn on tests 4-5 dB are entered in a statistical error, the term of sensitivity ceases to be objective and passes in a subjective plane. It is possible to continue to give examples, but let me stop on it, having noted only, that on quality of communication phones with the external aerial and built - in do not differ, it is the other myth of mobile communication.

Modern phones provide high quality of communication but if in your device are constantly audible noise, crash, echo, communication breaks, the interlocutor of yours does not hear you, that time to turn into the service center. Probably some troubles with your phone, a concrete sample, and not at all similar devices of this manufacturer. To do global conclusions it is necessary, as minimum, to test a little such phones from various factory parties.

And, at last, I will tell, how frequently users define sensitivity by eye. So, for a long time all known phone Sony Ericsson T68i has recommended itself, as the reliable device which does not have problems with reception quality. This platform has been licensed by other large manufacturer, on the basis of it the model of the same class is let out. Users assert that Т68i works better than this device, it's more sensitive. Under our request this statement has been checked up in laboratory conditions, devices, predictably, have shown similar results. So, that sensitivity is only psychological and by no means an objective category.

Eldar Murtazin ([email protected])
Translated by Andreas von Horn ([email protected])

Published — 02 April 2003

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