Basic design of a mobile phone

Today I want to talk about how to read diagrams correctly mobile phones. I will try to tell you the most basic things that a master should know. So. Where to start? The first thing you need to know. This is what the microcircuits are called and how they are designated on the diagrams.

1. Processor. The processor is usually signed on the CPU or RAP, RAPIDO circuit. They are most often square and most often the largest. If it is Nokia, then in most cases there is a “skirt” along the rim of the processor. In new Nokia models you can often find a processor mounted on a flash drive. They are called “sandwich”, this is the worst thing that can happen after the compound) what is the compound sometime later.
2. Flash drive. A flash drive on the diagrams is written as flash and somewhere I came across mem, memory. She most often rectangular shape. And remember, in Nokia phones the processor and flash drive can only be changed in pairs. And they only fit from an identical model. What I mean is that, for example, Nokia 6233 and 6300 phones have the same processor. But this is only in appearance! They won't work!

3. Power controller. It is signed on the diagrams with different “names”: it can be written retu, tahvo, betty, UEM - all this is a power controller. Most of them are small square chips.
4. Also, any mobile phone has a receiver and transmitter RF chip and GSM FEM. You need to be more careful when replacing transmitters. Some look identical but the last numbers in the markings are different. But they don't work on other phones. Others may be similar and fundamentally different numbers but will work. In the process of work, you can do it for yourself. Using your experience, build a model compatibility diagram.
These were the most basic ones in my opinion. If you have any questions about microcircuits and their designation. And in general any questions regarding mobile phone repair. Ask in the comments or write on Skype. The number can be found in my contacts

I'll add another example Nokia phone 6233 picture with the location of these parts

I remembered! There are 2 more important details in phones. Not everything is true. Briefly speaking. This is a thermistor and fuse. The fuse is most often used for charging. But in some phones it can also be found on camera. It burns out very often. And then you have to install a jumper. And a thermistor. What is a thermistor? This is such an insidious nasty thing)) The thermistor is in the phone charging circuit and is responsible for overheating. Very often this thermistor bursts after an impact or rots after water. Then the phone, when connected to the charger, starts to write “invalid battery” or “ charger not acceptable” or something else there. I don’t remember everything anymore. In this case, it is a thermistor. How can they be found on the diagram? Yes, very simple! The fuse is located immediately behind the connector and is called FUSE, and the thermistor is BTemp. We must also remember. that the thermistor cannot be replaced by anything. Only with a different thermistor. Jumpers are snot) in this case do not roll. That's all for today. I'm tired of writing))

Mobile phone is multifunctional device, whose main task is to provide cellular communication. At the present stage, manufacturers have equipped it a large number functions, which brings products closer of this type to smartphones. As a result, the cell phone today provides the user with necessary tools, without which many can no longer do. Among them are video cameras, players, editors and surfing the Internet.

Accordingly, such a small portable assistant, “under the hood” of which various capabilities are collected - indispensable device on any journey. With it you can:

Get in touch
Send an email.
Record video and audio.
Solve questions using the organizer.
Take a photo, etc.

But even protected devices can fail. In this case, to purchase components that have become unusable, you will need to visit an online store of spare parts for cell phones. To better understand what spare parts are needed to repair a travel phone while traveling, let’s take a closer look at its hardware functionality.

Basic phone details

The most important detail of any device is its motherboard. Today it looks like a small plate, often located along the entire internal length and width of the product, taking into account the presence of a battery and a display. Most other components are attached directly to it, and interfaces and other parts and modules are directly connected to the board. This is the basis of the phone.

In second place after the motherboard in importance is the microprocessor. This is the “engine” of the device, its main computing power, with which it is connected RAM. Random access (system) memory is responsible for the simultaneous use (activation) of various preinstalled software features.

No less important component– built-in memory (ROM). If the device does not have ROM, then it does not have the ability to process information, display it on the display, etc. – because there is simply no data. All software components focused on permanent memory. This module can be expanded in the form of a memory card slot, which usually accepts drives several times larger than the ROM capacity.

Other smartphone components

Cellular module. Responsible for connecting through cell towers.
Vibration motor. Transmits a signal to the user through vibration of the smartphone.
Audio module. Usually represented by external and internal speakers.
Display. Allows you to receive visual information and easily navigate the software component.
External protective elements (plugs, films, gaskets, tempered glass etc.).
Camera components. These are sensors, flashes, etc.
Microphone. Responsible for transmitting audio to the phone.
Keyboard. Mechanical part of functional control.
Auxiliary modules – accelerometer, hygrometer, etc.
Wireless modules. Allows you to synchronize with other devices over the air.
GNSS modules.
Battery
Coaxial cables, all kinds of cables, etc.

In addition, there are additional parts for phones with advanced functionality. For example, for repairs you will need a corresponding radio module and connector for external antenna. There is also large number small, but no less significant components– external connectors, bolts for protective housings, etc.

As it becomes clear, a modern cell phone is a complex electronic and electrical device that combines powerful functionality and has enormous potential for further development. Therefore, the ability to navigate its structure will be at least superficially useful to any traveler. This will allow you to quickly navigate and purchase the right part, especially since experienced tourists can replace many components themselves.

It is hardly possible today to find a person who has never used a cell phone. But does everyone understand how cellular communications work? How does what we have all become accustomed to work and work? Are signals transmitted from base stations about the wires or does it all work somehow differently? Or maybe all cellular communications function only through radio waves? We will try to answer these and other questions in our article, leaving the description of the GSM standard outside its scope.

At the moment when a person tries to make a call from his mobile phone, or when they start calling him, the phone is connected via radio waves to one of the base stations (the most accessible), to one of its antennas. Base stations can be seen here and there, looking at the houses of our cities, at the roofs and facades of industrial buildings, at high-rise buildings, and finally at the red and white masts specially erected for stations (especially along highways).

These stations look like rectangular boxes gray, of which in different sides various antennas stick out (usually up to 12 antennas). The antennas here work for both reception and transmission, and they belong to the cellular operator. The base station antennas are directed in all possible directions (sectors) to provide “network coverage” to subscribers from all directions at a distance of up to 35 kilometers.

The antenna of one sector is able to simultaneously service up to 72 calls, and if there are 12 antennas, then imagine: 864 calls can, in principle, be serviced by one large base station at the same time! Although they are usually limited to 432 channels (72*6). Each antenna is connected by cable to the control unit of the base station. And blocks of several base stations (each station serves its own part of the territory) are connected to the controller. Up to 15 base stations are connected to one controller.

The base station is, in principle, capable of operating on three bands: the 900 MHz signal penetrates better inside buildings and structures and spreads further, so this band is often used in villages and fields; a signal at a frequency of 1800 MHz does not travel that far, but more transmitters are installed in one sector, so such stations are installed more often in cities; finally 2100 MHz is a 3G network.

Of course, there may be several controllers in a populated area or region, so the controllers, in turn, are connected by cables to the switch. The purpose of the switch is to connect operator networks mobile communications with each other and with regular city lines telephone communication, long distance communication And international communications. If the network is small, then one switch is enough; if it is large, two or more switches are used. The switches are connected to each other by wires.

In the process of moving a person talking on a mobile phone along the street, for example: he walks, drives public transport, or travels in a personal car - his phone should not lose the network for a moment, you cannot interrupt the conversation.

Continuity of communication is obtained due to the ability of a network of base stations to very quickly switch a subscriber from one antenna to another as he moves from the coverage area of ​​one antenna to the coverage area of ​​another (from cell to cell). The subscriber himself does not notice how he ceases to be connected to one base station and is already connected to another, how he switches from antenna to antenna, from station to station, from controller to controller...

At the same time, the switch provides optimal load distribution across a multi-level network design to reduce the likelihood of equipment failure. A multi-level network is built like this: cell phone - base station - controller - switch.

Let's say we make a call, and the signal has already reached the switchboard. The switch transmits our call towards the destination subscriber - to the city network, to the international or long-distance communication network, or to the network of another mobile operator. All this happens very quickly using high-speed fiber optic cable channels.

Next, our call goes to the switch, which is located on the side of the recipient of the call (the one we called). The “receiving” switch already has data about where the called subscriber is located, in what network coverage area: which controller, which base station. And so, the network polling begins from the base station, the recipient is located, and a call is received on his phone.

The entire chain of events described, from the moment the number is dialed to the moment the call is heard on the receiving end, usually lasts no more than 3 seconds. So today we can call anywhere in the world.

Andrey Povny

In order to find out the phone device, find out principle GSM work mobile communications wrote this review.

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Next, you can find and read about the structure of a cell phone and its main functional components. Find mobile device diagrams. Learn how a mobile phone works and how the GSM channel works. Design and circuitry telephone sets cellular communication standard GSM.

Spare parts and repair of mobile phones.

Store spare parts and components for phones, tablets, smartphones

radiomaster.net- another Internet service that provides downloads to your computer or phone of phone device diagrams and instructions for simple and mobile phones and other equipment. Mobile phone diagrams are downloaded from the site for free, without advertising and SMS, directly from this site. At the time of writing this review, download free diagrams for cell phones, is possible for more than 600 models of mobile devices.

market.yandex.ru- search and purchase of spare parts for mobile and cell phones through the irreplaceable Yandex.Market service. As always, for users of the service it is convenient to sort and search for phone parts by price and the nearest location of the cell phone spare parts store.

Almost everyone used a cell phone, but few people thought about how it all works? In this literary opus we will try to consider how communication occurs from the point of view of your telecom operator.

When you dial a number and start calling, well, or someone calls you, your device communicates via radio channel with one of the antennas of the nearest base station.

Each of the base stations contains from one to twelve transceiver antennas, directed in different directions, to provide communication to subscribers from all directions. In professional jargon, antennas are also called “sectors”. You yourself have probably seen them many times - large gray rectangular blocks.

From the antenna, the signal is transmitted via cable directly to the control unit of the base station. The set of sectors and a control block is usually called - BS, Base Station, base station. Several base stations, whose antennas serve a specific territory or area of ​​the city, are connected to a special unit - the so-called L.A.C. Local Area Controller, “local zone controller”, often called simply controller. Up to 15 base stations are usually connected to one controller.

In turn, the controllers, of which there may also be several, are connected to the very central “brain” unit - MSC, Mobile services Switching Center, Control Center Mobile services , popularly known as switch. The switch provides output (and input) to city telephone lines, to other cellular operators and so on.

That is, in the end the whole scheme looks something like this:

Small GSM networks use only one switch; larger ones, serving more than a million subscribers, can use two, three or more M.S.C., united with each other.

Why such complexity? It would seem that you could simply connect the antennas to the switch - and that’s it, there would be no problems... But it’s not so simple. It's all about one simple English word - handover. This term refers to handover in cellular networks. That is, when you are walking down the street or driving a car (train, bicycle, roller skates, asphalt paver...) and at the same time talking on the phone, then in order for the connection not to be interrupted (and it is not interrupted), you need to switch in time Your phone from one sector to another, from one BS to another, from one Local Area to another, and so on. Accordingly, if the sectors were directly connected to the switch, then all these switchings would have to be managed by the switch, which already has something to do. A multi-level network design makes it possible to evenly distribute the load, which reduces the likelihood of equipment failure and, as a result, loss of communication.

Example - if you and your phone move from the coverage area of ​​one sector to the coverage area of ​​another, then the BS control unit handles the transfer of the phone, without affecting the “superior” devices - L.A.C. And M.S.C.. Accordingly, if the transition occurs between different B.S., then it is controlled L.A.C. and so on.

The operation of the switch should be considered in a little more detail. A switch in a cellular network performs almost the same functions as a PBX in a wired network. telephone networks. It is he who determines where you call, who calls you, and is responsible for the work additional services, and, in the end, generally determines whether it is possible to call or not.

Let's stop at the last point - what happens when you turn on your phone?

Here, you turn on your phone. Your SIM card has special number, the so-called IMSI – International Subscriber Identification Number. This number is unique for every SIM card in the world, and it is precisely by this number that operators distinguish one subscriber from another. When you turn on the phone, it sends this code, the base station transmits it to LAC, LAC– to the switch, in turn. Two things come into play here additional modules associated with the switch – HLR, Home Location Register And VLR, Visitor Location Register. Respectively, Register of Home Subscribers And Register of Guest Subscribers. IN HLR are stored IMSI all subscribers who are connected to this operator. IN VLR in turn, contains data about all subscribers who are in at the moment use the network of this operator. IMSI transferred to HLR(of course, in a highly encrypted form; we will not go into detail about the features of encryption, we will only say that another block is responsible for this process - AuC, Authentication Center), HLR, in turn, checks whether he has such a subscriber, and, if so, whether he is blocked, for example, for non-payment. If everything is in order, then this subscriber is registered in VLR and from now on can make calls. Large operators may have not one, but several working in parallel HLR And VLR. Now let’s try to display all of the above in the figure:

Here we briefly looked at how it works cellular network. In fact, everything there is much more complicated, but if we describe everything as it is in detail, then this presentation may well exceed “War and Peace” in volume.

Next, we will look at how (and most importantly, why!) the operator debits money from our account. As you've probably already heard, tariff plans there are three different types– the so-called “credit”, “advance” and “prepaid”, from English Pre-Paid, that is, prepaid. What's the difference? Let's look at how money can be written off during a conversation:

Let's say you called somewhere. It was recorded on the switchboard that subscriber such and such called there and talked for, say, forty-five seconds.

The first case is that you have a credit or advance payment system. In this case, the following happens: data about your and not only your calls is accumulated in the switch and then, in the order of the general queue, is transferred to a special block called Billing, from English to bill - to pay bills. Billing is responsible for all issues related to subscribers' money - calculates the cost of calls, writes off subscription fees, writes off money for services, and so on.

Speed ​​of information transfer from M.S.C. V Billing depends on how much computing power you have billing, or, in other words, how quickly he manages to convert technical data about calls made into direct money. Accordingly, the more subscribers talk, or the more “slow” the billing, the slower the queue will move, and accordingly, the greater the delay between the conversation itself and the actual debiting of money for this conversation. This fact is associated with the dissatisfaction often expressed by some subscribers - “They say they are stealing money! I didn’t speak for two days - a certain amount was written off...” But it does not take into account at all that for conversations that took place, for example, three days ago, the money was not immediately written off... Good people they try not to notice... And these days, for example, billing could simply not work - due to an accident, or because it was somehow modernized.

IN reverse side– from billing to M.S.C.- there is another queue in which billing informs the switchboard about the status of subscribers' accounts. Again, a fairly common case - the debt on the account can reach several tens of dollars, but you can still make phone calls - this is precisely because the “reverse” queue has not yet arrived and the switchboard does not yet know that you are a malicious defaulter and You should have been blocked a long time ago.

Advance tariffs differ from credit tariffs only in the method of settlement with the subscriber - in the first case, a person deposits some amount into the account, and money for calls is gradually deducted from this amount. This method is convenient because it allows you to plan and limit your communication costs to some extent. The second option is credit, in which the total cost of all calls for any period (“ billing cycle"), usually per month, is issued in the form of an invoice that the subscriber must pay. The credit system is convenient because it insures you against those cases when you urgently need to make a call, but the money in your account suddenly runs out and your phone is blocked.

Prepaids are designed completely differently:

In the prepaide billing as such is usually called " Pripad platform».

Immediately at the moment the telephone connection starts, a direct connection is established between switch And prepaid platform. No queues, data is transmitted in both directions directly during the conversation, in real time. In connection with this, prepaids have the following characteristic features: the absence subscription fee(since there is no such thing as billing period), a limited range of additional services (they are technically difficult to charge in “real time”), the inability to “go into the red” - the conversation will simply be interrupted as soon as the money in the account runs out. Clear dignity preipedes is the ability to accurately control the amount of money in the account, and, as a result, your expenses.

IN preipedes sometimes a funny phenomenon is observed - if prepaid platform for some reason refuses to work, for example, due to overload, then, accordingly, for subscribers prepaid tariffs at this time all calls become absolutely free. Which, in fact, makes them – the subscribers – happy.

But how is our money calculated when we talk while in roaming? And how does the phone work in roaming? Well, let's try to answer these questions:

Number IMSI consists of 15 digits, and the first 5 digits, the so-called СС – Country Code(3 digits) and NC – Network Code(5 digits) – clearly characterize the operator to which it is connected this subscriber. According to these five numbers VLR finds the guest operator HLR home operator and looks in it - but, in fact, can this subscriber use roaming with this operator? If yes, then IMSI is registered with VLR guest operator, and in HLR home - link to the same guest VLR to know where to look for the subscriber.

The situation with writing off money in billing is also not very simple. Due to the fact that calls are processed by the guest switch, but the “home” switch counts the money billing, quite possible long delays in debiting funds – up to a month. Although there are systems, for example, “ Camel2”, which even in roaming work on the prepaid principle, that is, they write off money in real time.

Here another question arises - what is the money written off for? roaming? If “at home” everything is clear - there are clearly defined tariff plans, then with roaming the situation is different - a lot of money is written off and it is not clear why. Well, let's try to figure it out:

All phone calls in roaming are divided into 3 main categories:

Incoming calls – in this case, the cost of the call consists of:

Costs international call from home to guest region
+
Cost of an incoming call from a guest operator
+
Some surcharge depending on the specific guest operator

Outgoing call home:

Cost of an international call from the guest region to home
+
Price outgoing call at the guest operator

Outgoing call to guest region:

Cost of an outgoing call from a guest operator
+
Some surcharge depending on the specific operator

As you can see, the cost of calls in roaming depends only on two things - on which operator the subscriber is connected to at home and which operator the subscriber uses when away. This reveals one very important thing - the cost of a minute in roaming absolutely does not depend on the tariff plan chosen by the subscriber.

I would like to add one more remark - if two phones of one operator are roaming together with another operator (well, for example, two friends went on vacation), then it will be very expensive for them to talk to each other - the caller pays as for outgoing home, and the recipient pays the call is like someone coming from home. This is one of the disadvantages of the GSM standard - that communication in this case goes through the house. Although technically it is quite possible to arrange a connection “directly”, which operator will do this if you can leave everything as it is and make money?

One more question, in lately owners of more than one mobile phone are often interested in – how much will a forwarded call from one phone to another cost? And it’s quite possible to answer this question:

Let’s say call forwarding is set from phone B to phone C. A call is made from phone A to phone B - accordingly, the call is forwarded to phone C. In this case, they pay:

Phone A – as for outgoing to phone B
(actually, this is logical - after all, that’s what he’s calling)
Phone B – pays the forwarding price
(usually a few cents per minute)
+
the cost of an international call from the region where B is registered to the region where C is registered
(if the phones are from the same region, then this component is zero).
Phone C – pays as for incoming calls from phone A

In conclusion, I would like to mention one more subtle point - how much will forwarding in roaming cost? And here's where the fun begins:

For example, the phone has a call forwarding based on busy conditions to home number. Then at incoming call the so-called “ roaming loop" - the call will go to home phone via guest switch, accordingly, the cost of such a forwarded call for roamer will be equal to the sum of the costs of incoming and outgoing calls to home plus the cost of the forwarding itself. And what’s funny about this is that the roamer may not even know that such a call took place, and subsequently be surprised when he sees the bill for communication.

It follows practical advice– when traveling, it is advisable to disable all types of forwarding (you can leave only unconditional - in this case, a “roaming loop” does not work), especially forwarding to voicemail- otherwise, later you can wonder for a long time - “Where did that money go, huh?”

List of terms used in the text:

AuC– Authentification Center, Authentication Center, is responsible for encoding information when transmitted over the network and received from the network
Billing– Billing, accounting system cash from the operator
B.S.– Base Station, base station, several transceiver antennas belonging to one control device.
Camel2– one of the Prepaid systems, which implements instant debiting of funds in roaming
CC– Country Code, country code in GSM standard(for Russia – 250)
GSM– Global System for Mobile Communications, the most widespread cellular communication standard in the world
Handover – transfer of handset control from one antenna/base station/LAC to another
HLR– Home Location Register, a register of home subscribers, contains detailed information about all subscribers connected to this operator.
IMEI – International Mobile Equipment Identification, international serial number equipment in the GSM standard, unique for each device
IMSI– International Mobile Subscriber Identification, the international serial number of a subscriber for GSM standard services, is unique for each subscriber
L.A.C.– Local Area Controller, Local Zone Controller, devices, work manager a certain number of base stations whose antennas serve a certain area.
Local Area– Local zone, an area served by BSs that are part of the same LAC
M.S.C.- Mobile services Switching Center, Mobile Services Control Center, switch – central link GSM networks.
NC– Network Code, Network Code, the code of a specific operator in a given country in the GSM standard (for MTS – 01, BeeLine – 99).
Prepaid– Prepaid, prepayment – ​​a billing system based on instant debiting of funds.
Roaming– Roaming, using the network of another, “guest” operator.
SIM– Subscriber Identification Module, Subscriber Identification Module, SIM card – an electronic unit inserted into the phone on which the subscriber’s IMSI is recorded.
VLR– Visitor Location Register, a register of active subscribers – contains information about all subscribers who are currently using the services of this operator.