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Analysis of mobile phone out of service area

Often consulted by friends. Why do you often encounter the situation of calling others or others calling yourself "the mobile phone is not in service area", or sometimes the phone is suddenly interrupted during the call, and sometimes the text message is delayed or not received? What is the reason?

Bad cell phone signal is usually due to network reasons, which may also lead to SMS delay and other problems. Network problems generally lead to the interruption of calls for the following reasons.

First of all, the cell phone in the signal blind area will cause "out of service area" or call interruption. This blind area includes places beyond the network coverage, such as suburbs and rural areas where there are no network communication facilities, and places in cities where mobile phones are blocked by shields and signals cannot be covered, such as elevators, underground places and buildings.

Secondly, the phenomenon of poor signal caused by interference. Because the signal received by the mobile phone works through the propagation of electromagnetic waves, the base station establishes contact with the mobile phone by transmitting electric waves, thus achieving the purpose of voice call. Therefore, the interference of electromagnetic waves will have a negative impact on mobile phones. When the interference of some electromagnetic waves in the air exceeds a certain level and the signal-to-noise ratio of the mobile phone drops below the standard value, the mobile phone will have no signal or be disconnected. Therefore, it is best for consumers to stay away from devices that can emit powerful electromagnetic waves and make phone calls in places with little interference.

Third, the call was dropped due to handover failure. Network operators transmit wireless signals through base stations to serve users. The range of base stations is limited, so there may be many base stations in an area. All base stations are combined into a network system, and each base station has its own coverage. If it exceeds this range, the mobile phone will have to change the base station, so as to keep the mobile phone online all the time. When the user jumps from one service cell to another during the call, the voice channel of the user will also be switched from the original service cell. However, if the new service cell is busy at this time and there are no extra channels allocated to the user, the switching of the service cell will fail, and the call process of the user will be interrupted. Adding more base stations can appropriately alleviate this situation, but it will also increase the cost. Too many base stations will also increase radiation and pollute the environment. Therefore, how to make handover difficult without increasing the number of base stations is a problem that network operators strive to solve.

Also, due to temporary network failure, or the network is particularly busy, it will also cause poor cell phone signal. For example, in a busy business district, there may be cases where the phone cannot be dialed out or dialed in.

In addition to the poor signal caused by network reasons, another problem is the user's mobile phone. Dirty contacts of SIM card of mobile phone will also cause poor reception and transmission signals, so just take out the card and wipe it clean. Some mobile phone users have taken some "special measures"-when the mobile phone is turned on, unplugging the battery will produce an "out of service area" response effect. It is reported that some people use this method to avoid answering the phone. However, the staff of the maintenance center suggest that frequent use of this method will shorten the life of the SIM card and eventually cause damage to the mobile phone.

Analysis of dropped calls on mobile phones.

Cell phone disconnection means that the two sides of the call terminate the call abnormally for some reason. It is a technical problem that mobile communication is trying to solve but not completely overcome. There are generally three reasons why a mobile phone is dropped:

First, the strong interference of radio waves will cause disconnection. Because mobile communication is spread through air waves, when some air waves interferes with the radio waves in use to a certain extent, the signal-to-noise ratio will drop below the standard value, and the mobile phone will automatically turn off and drop the line.

Second, the transmission will be blocked, the building will reflect, and it will also interfere with the radio waves at the receiving point, leading to disconnection.

Third, the handover failed and the call was dropped. When the call location continues to cross from one service cell to another or cross again, the voice channel of the user's call needs to be switched from the original cell to the new service cell, but the users in the new service cell are busy at random. If no effective voice channel is provided during the handover, the handover will fail, resulting in the call being dropped.

If the call is suddenly dropped, you can move and change the location to avoid using it in a dead corner. If you are disconnected continuously, you can contact the relevant departments to explain the call situation at your location so as to solve it as soon as possible.

Causes and countermeasures of low quality of mobile phone call

With the progress and development of society, mobile phones have become an indispensable communication tool in people's lives. However, people sometimes encounter "troubles" brought by mobile phones. For example, when answering an important phone call, the phone suddenly disconnects, so how did these situations happen and how to solve them?

1. One of the reasons why the mobile phone is often disconnected during the call is that the owner of the base station powered by the mobile phone did not pay the electricity fee to the power supply bureau, and the internal power supply kept working normally for several hours at most. In addition, the signals between base stations cover each other, and a similar situation will occur when using mobile phones in this area. It can also be said that the signal has been disturbed. Generally, this kind of situation is rare, and there is no substantive solution.

2. When the call area is switched, the mobile phone will be disconnected because the conditions are not available. When we use mobile phones, if we move from one place to another, the reception of mobile phone signals will continue from one service cell to another due to the change of the user's location. However, the channel idle state of each service cell is random, so it is likely that when the user's call channel is switched from the original cell to the new cell, the channel of the new cell is in a busy state, and the mobile phone being used may be forced to interrupt because there is no signal transmission channel. Under normal circumstances, users can't solve this situation, and only the communication department can make the communication channels smooth.

3. When using a mobile phone, it may be disconnected as soon as it is connected, or it may take two or three times to connect. This may be a network failure. With more and more users using mobile phones, GSM or CDMA network systems are becoming more and more complex, and there are more and more devices. At the same time, because the equipment of these network systems is introduced earlier, the version is often lower and the adaptability is not strong, which leads to the failure of the whole network system. Users can't solve this problem by themselves, but only hope that the communication department can maintain and manage the network system in time to ensure the normal communication of mobile phones.

Of course, when we go to a remote place or a closed building, it is very common for our mobile phone to be disconnected. This is because the signal received by the mobile phone suddenly becomes weak or gone. If this happens, we can completely lengthen the antenna of the mobile phone, because the antenna must be used to receive signals in places with poor reception effect; If it still doesn't work, we can look at the signal strength displayed on the screen of the mobile phone. If the signal is really weak, we should move it to a relatively open position, such as near a window. If the above measures still can't guarantee the normal answering of your mobile phone, you should check whether your mobile phone is set with call forwarding and call prohibition. If so, just reset it.

5。 If the information is intermittent when the phone is answering, the sound is particularly low or only noise is heard, it may be that your phone is affected by nearby electromagnetic waves. Because when mobile phones are interconnected, signals are transmitted in the air in the form of radio waves through GSM or CDMA systems, in this process, signals will inevitably be coherent with other radio waves, which will directly affect the normal transmission of transmitted signals to receiving mobile phones. For this phenomenon, we should try to avoid using mobile phones near high-rise buildings.

6。 Of course, in addition to external influences, the failure of the mobile phone itself will also lead to disconnection. If the mobile phone can answer normally at first, but it can't answer later, it is that there is something wrong with the signal receiving part of the mobile phone. If the call quality is not high or the call is repeatedly dropped, you need to contact the relevant departments to find out the cause of the problem.

Don't forget that your mobile phone battery is dead or the battery is not in good contact with the mobile phone, and the mobile phone will be disconnected.

It's best not to use cell phones or surf the Internet in a thunderstorm.

Meteorologists reminded today that after the summer solstice, thunderstorm weather has entered a period of high incidence, so we must be alert to lightning strikes. In a thunderstorm, it's best to stop using mobile phones and don't use modems or ADSL devices to surf the Internet. It is best to unplug the computer and make sure that the computer has a good grounding. It is best to install lightning arrester for household appliances. Don't pull bare metal wires from outdoor to indoor, try not to answer and dial mobile phones, and avoid ordinary phones when they are struck by lightning.

Cell phone battery analysis

Looking at the flat and tightly sealed mobile phone battery and thinking about its high price, have you ever wondered: What is in the mobile phone battery?

Open the cell phone battery, and you will find that the internal structure of the cell phone battery is not complicated:

Several batteries about the size of No.5 or No.7 are connected in series, plus a protective circuit or switching device. It's that simple. Taking the 6V Ni-MH battery of Ericsson 398 mobile phone standard as an example, we connect 5 1.2V single Ni-MH rechargeable batteries or 4 1.5V single Ni-MH rechargeable batteries in series through special circuits (usually thin film circuits), and are equipped with overheating protection circuits, so as to make the mobile phone battery we see.

The internal structure of mobile phone battery looks simple, but the performance of mobile phone battery is very different. Mainly depends on the equilibrium identity of the single rechargeable battery that constitutes the mobile phone battery. The excellent performance of mobile phone battery requires that the internal resistance, capacitance, charging characteristics, discharge characteristics and other indicators of its internal single battery be as consistent or similar as possible. Such batteries are combined together, and each battery is charged and discharged almost simultaneously; For the single battery, the problem of overcharge or overdischarge will not occur, so that the whole mobile phone battery can reach the ideal state of long life, large capacity and good stability. If the internal resistance, capacitance, charging and discharging characteristics of single cells are quite different, the overall matching performance will be reduced. When used in mobile phones, it is prone to problems such as insufficient power, noisy sound quality, short standby time and easy interruption of calls. What's more, if the single battery appears alkali creep, it may corrode the contacts of the mobile phone. If the internal pressure of single battery is too high, if the safety protection device fails to play its role in time (especially during fast charging), it may explode and damage the mobile phone. The structure of mobile phone battery is relatively simple and easy to counterfeit. Counterfeit mobile phone batteries are easy to burn because of the lack of protective circuits, so consumers must pay attention to distinguish the authenticity when buying mobile phone batteries. You get what you pay.

Tips for first aid of mobile phone falling into water

Once the mobile phone is flooded, take out the battery immediately, and never turn it on immediately to understand the situation of the mobile phone. Do not use a hair dryer after removing the battery. Send it to a professional for water treatment immediately. If it falls into sewage or corrosive substances, it should be cleaned by ultrasonic wave first, and then dried before the next maintenance treatment. If the mobile phone can still be used after being flooded, it should be sent to a professional to prevent the circuit board from being corroded and irreparable.

Five fears of mobile phones

Do you know what cell phones are most afraid of? Of course, in addition to your "intentional killing", the compulsion of nature and your own carelessness are the reasons for shortening its life! The author here provides five "most afraid" mobile phones for your reference.

The first fear: water and humidity. Avoid using the mobile phone in humid environment (seaside/rainy day) to avoid a large amount of water vapor invading the circuit board to form water stains, resulting in short circuit or oxidized metal interfaces. Because if the charging hole is oxidized, it is easy to burn the machine when charging. Mobile phones should be used moderately to generate a certain temperature inside them and naturally evaporate the water vapor accumulated at ordinary times. And if the mobile phone is idle for a long time, it needs special moisture-proof treatment. Soak in water: what can still be alive and kicking after soaking in water? Sulfur: mobile phones should be avoided in places with heavy sulfur, so as not to aggravate metal oxidation.

Second fear: dust. The accumulation of dust will also affect the current conduction between circuit board contacts. Grease: When the mobile phone panel is used for a long time, the grease on the face may penetrate into the fuselage, pollute the internal wiring and cause damage!

The third fear: hot and high temperature. Mobile phones should avoid being exposed to high temperature. Especially in summer, it is easy to replace the circuit board or battery due to high temperature in the car, and the screen is also easy to be deformed due to material changes. Temperature difference: the temperature difference when the mobile phone enters and exits the air-conditioned room. The water vapor condensed by cold air may corrode the circuit board, causing short circuit of electronic components and affecting the life of the mobile phone!

The fourth fear: falling or colliding. Basic knowledge, mechanical collision is easy to damage. Squeezing: The mobile phone is squeezed hard. Although the damage is not as direct as falling off the machine, some screens have black spots, mostly caused by the liquid crystal being squeezed and broken. Because the pressure that LCD can bear is quite limited, users must pay attention!

Fifth fear: charging and batteries. If the original battery is not used, the contact between the mobile phone and the battery is not as close as the original battery. Long-term shaking down may lead to contact relaxation and instant power failure.

Charging: Don't turn on the phone when charging, so as to avoid the high temperature when charging the phone affecting the circuit board. After the car is started, the car charger should be plugged in to avoid the instantaneous peak current flowing back to the mobile phone through the circuit and damaging the internal parts. Friends who often go abroad had better bring more spare batteries, otherwise they must use the original charger to avoid damage to the machine due to different voltages.

Static electricity: The human body is charged with static electricity. If the disassembly and assembly of the mobile phone is not carried out on a platform that can release static electricity, impurities may be brought into the fuselage by static electricity, causing a short circuit.

What should I do if I encounter a mobile phone virus?

Any electronic product with memory may be infected with "virus". Like a mobile phone with data transmission, it is not difficult to write some junk instructions to the mobile phone system.

Attacks on mobile phones are nothing more than three levels: First, WAP phones cannot receive normal information by attacking WAP servers. The second is to attack and control the "gateway" and send a large number of spam messages to mobile phone users. Third, direct attacks on the mobile phone itself, targeted attacks on its operating system and running programs, so that the mobile phone can not provide services. Here are some ways to deal with the mobile phone virus that has already appeared:

1, "EPOC" virus

There are six kinds of viruses * * *: The virus that can disable keyboard operation is "EPOC _ Loneliness". One ". When the computer executes this program, it will display the screen displayed when receiving files in infrared communication, and the virus will be stored in the memory. After the virus memory exists, "Warning-Virus" will be displayed on the computer screen, and no keyboard operation will be accepted thereafter. But if you enter "leavemealone", you can cancel the right of residence-it's very similar to the cheating password in the game. Among the other five viruses, "EPOC _ alarm" is a continuous warning sound; And "BANDINFO of EPOC". A "change the user information to" someone's book "; "EPOC _ fake. A "is very similar to a joke applet that was widely circulated before: displaying pictures when formatting the built-in hard disk without actually performing the formatting operation; "EPOC _ ghost. A "displays" Everyonehatettsyou "on the screen; "EPOC _ lighting. A "Keeping the backlight flashing continuously looks more like a joke than a virus.

2、“ACE—？” virus

If a mobile phone virus report recently released by a website receives a byte of "ACE—-?" Don't start calling. If the call function is enabled, the mobile phone will be infected with a virus. The outbreak of the virus will make the mobile phone unable to connect to the network.

3. "Unavailable" virus

This is a virus that first appeared in Vietnam to destroy mobile phones. When the other party dials, the phone number of the caller should be displayed on the screen, but the words "Unable to connect" or some strange symbols are displayed. Don't answer the phone at this time, or you will get a virus, and all the information and settings in the machine will be destroyed (including the phone that pays to use the calling card). Once this happens, you may need to get a new mobile phone.

4. Mobile phone-specific virus

Researchers at ITSX, a Dutch security company, have found that there are loopholes in the operating systems of some popular Nokia phone models. Hackers can use this security vulnerability to send deformed electronic text messages with the length less than 160 characters to the mobile phone, causing the operating system to crash. This harmful SMS virus mainly damages Nokia 33 10, 3330 and 62 10 mobile phones. Nokia confirmed the existence of the above security vulnerability and said that it had been fixed last year, but many old mobile phones are still vulnerable to attacks. And hackers. Cell phone. Smsdos that specifically attacks all kinds of Siemens mobile phones. This virus can send a virus program in the form of short messages to Siemens mobile phone users through the Internet or mobile phones, causing the other mobile phone to automatically shut down.

In addition to all kinds of viruses mentioned above, some IBM researchers recently said that the SIM cards of some cellular phones can be cloned in a few minutes, so that hackers can make calls and transfer the phone bill to the victim's account. Hackers mainly use an intrusion technology to analyze the current flow direction of the mobile phone security identity confirmation card, and then crack the password stored in the security card. Fortunately, this technology can only crack the password of the first generation GSM mobile phone security card, and the hacker must personally touch the mobile phone he wants to attack within 1 to 2 minutes. IBM researchers designed a technical patch to prevent the above attacks. Experts pointed out that for ordinary mobile phone users, the simplest preventive measure is: don't lend your mobile phone to strangers easily.

I'll tell you when I think of it! ! Everybody learn from each other! ! Ha ha! ~