đš On Sun, 25 Dec 2022 at 01:35, 'gopala krishnan' via Thatha_Patty < [email protected]> wrote:
> *MOBILE PHONE PART 3* > > CONTINUED FROM PART 2 > > *17. The GSM System* > > Global System for Mobile Communications is the standard for mobile > telephone systems in the world. *In GSM, the signaling and speech > channels are digital, therefore GSM is considered a 2G (Second Generation) > system*. This helps wide-spread implementation of data communication > applications. *There are five different cell sizes in a GSM network These > are macro, micro, pico, femto and umbrella cells.* > > Macro cells are cells where the base station antenna is installed on a > mast above average roof top level. > > Micro cells are cells whose antenna height is under average roof top > level. > > Pico cells are small cells whose coverage diameter is a few dozen metres. > These are mainly used in indoors applications. > > Femto cells are cells designed for use in residential or small business > environments and connect to the service providerâs network via a broadband > internet connection. > > *Umbrella cells are used to cover shadowed regions* of smaller cells and > fill in gaps in coverage between those cells. Horizontal radius of the cell > varies depending on the antenna height, antenna gain and propagation > conditions. > > *Maximum distance the GSM supports is 35 kilometers*. Most 2G GSM > networks operate in the 900 MHz or 1800 MHz bands while 3G GSM in the 2100 > MHz frequency band. > > My note- Now 5 G is being implemented. This means better quality and > change in MHz > > *18 Time Sharing* > > Time Division Multiplexing technique is used to share eight full-rate or > sixteen half-rate speech channels per radio frequency channel. There are > eight radio time slots grouped into a TDMA frame. > > *19 Mobile Network* > > *Mobile phone converts voice, text, multi-media messages or data calls > into Radio Frequencies* (RF). *Mobile phone base stations transmit and > receive these RF signals and connect callers to other phones and other > networks*. Mobile phone network is divided into thousands of overlapping, > individual geographic areas or âcellsâ, each with a base station. The size > of a cell depends on the area of coverage and the number of calls that are > made in that area. The smallest cells are in crowded urban areas with > large buildings and heavy population density, while the biggest cells are > in rural areas, where people are dispersed. > > *20 Channels employed* > > There are two types of channels used in GSM . These are Control channels > and Traffic channels. > > *20a Control channels* > > These are responsible for housekeeping tasks such as telling the mobile > when a call is coming in and which frequency to use. To ensure this > handover works, *the phone constantly monitors the broadcast control > channel of up to 16 neighboring cells*. In normal operation, phones > continually adjust the power of the radio waves they send out to be the > minimum needed for the base station to receive a clear signal. *If a > phone moves far away from its base station and if the signal is weak, the > network consults the list and triggers a handover to a neighboring cell > with best signal.* > > *20b Traffic channels* > > > > It is used to carry calls or other data from the mobile phone to the base > station and vice versa. In the Traffic channel, voice or text data is > carried in bursts. Each burst comprises two consecutive strings of bits (a > series of signals representing 1s and 0s), each 57 bits long. > > *21 Range* > > The range within which mobile devices can connect is not a fixed figure. *It > depends on a number of factors like the frequency of signal in use, the > transmitterâs rated power, the transmitterâs size etc.* > > *My note- Often while we travel in train/ bus the* range differs, speech > becomes unclear or disrupted. With in the premises of home many times while > coming outside the speech becomes clear because range increases (The > resistance of walls in the home are removed and strong signals and > frequency is received. > > *22 Inside the Mobile phone* > > Mobile phone is a sophisticated device *using SMD components, > Microprocessor, Flash memory etc. In addition to the Circuit board, Mobile > phone also has Antenna, Liquid Crystal Display(LCD)* , *Keyboard, > Microphone, Speaker and Battery.* > > *The circuit board is the heart of the Mobile phone*. It has chips like > Analog-to-Digital and Digital-to-Analog conversion chips that translate the > outgoing audio signal from analog to digital and the incoming signal from > digital back to analog. > > *Following are the Chips present in Mobile phone.* > > 1Digital signal processor > > It is generally rated as having 40 MIPS (millions of instructions per > second) to conduct calculations of signal manipulation at high speed. This > chip deals with both compression and decompression of the signals. > > *2. Microprocessor* > > It handles all the housekeeping tasks for the keyboard and display. It > also deals with command and control signaling with the base station, and > coordinates the rest of the functions on the board. > > 3.The Flash memory > > *The Flash memory and ROM Chips of the Mobile phone act as a storage > location* for the phone. These chips store the customizable options of > the cell phone, as well as the entire operating system. The power and radio > frequency sections of the phone, phone recharging and power management etc > are controlled by this chip. It also controls several hundred FM channels. > *The > RF amplifiers focus on signals that go in and out of the phoneâs antennae.* > > *My note- Pressent day smart phones and ordinary* phones, the antenna is > not much visible protruding out if the device. It will be appearing > through a small hole to the right of charging connector in ordinary > phones and smart phones. > > 23 Mobile Phone Maintenance > > Mobile phone is a delicate device and needs care for its proper > functioning. Here are the common measures to keep the mobile phone in good > condition. > > *Do not keep Mobile phone in wet area* or use it with wet hands. Moisture > can cause non-repairable internal corrosion of parts. > > Do not drop the phone or damage the connection points. > > *Do not over stress the phone. It may damage the* display. > > *Do not keep the phone near heat generating* devices. High temperature in > a car can damage its electronics. > > *Do not over charge the battery. Charge the battery* only its charge > status goes below 50 percent. > > Prevent Cloning. > > *A phone is âClonedâ when someone steals its ID number and is able to make > fraudulent calls on the ownerâs account*. When the phone makes a call, it > transmits the ESN and MIN- a unique tag- for your phone to the network at > the beginning of the call. When the phone transmits its MIN/ESN pair, it is > possible to capture the ESN-MIN pair. Using a Scanner device it is easy to > modify another phone so that it contains your MIN-ESN tags. This allows the > person to make calls on your account. Cloning may also occurs when the > phone is repaired in an unauthorized service centre. It is possible to copy > the data including images and video present in the phone. > > *My note- Many other points like erasing memory* information, tapping a > mobile etc, which are commonly heard now, *are offences and punishable > under law* > > > > -- > You received this message because you are subscribed to the Google Groups > "Thatha_Patty" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/thatha_patty/1735012450.2861561.1671960891533%40mail.yahoo.com > <https://groups.google.com/d/msgid/thatha_patty/1735012450.2861561.1671960891533%40mail.yahoo.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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