It is very often we hear 3G and 4G technology.. and we use to speak more about it.. but when some one ask us what is the technical work behind it? we will be blinking for it...
so being a electronic and communication engineer i shouldn't blinking so i learned few about it and that is here...
The first generation in mobile communication technology is analog communication..In 1983, the analog cell-phone standard called AMPS (Advanced Mobile Phone System) was approved by the FCC and first used in Chicago. AMPS uses a range of frequencies between 824 megahertz (MHz) and 894 MHz for analog cell phones.
The transmit and receive frequencies of each voice channel are separated by 45 MHz to keep them from interfering with each other. Each carrier has 395 voice channels, as well as 21 data channels to use for housekeeping activities like registration and paging.

A version of AMPS known as Narrow band Advanced Mobile Phone Service (NAMPS) incorporates some digital technology to allow the system to carry about three times as many calls as the original version. Even though it uses digital technology, it is still considered analog. AMPS and NAMPS only operate in the 800-MHz band and do not offer many of the features common in digital cellular service, such as e-mail and Web browsing.
This uses FDMA (frequency division multiple access) -FDMA separates the spectrum into distinct voice channels by splitting it into uniform chunks of bandwidth.

This second generation in mobile communication technology is digital communication.GSM (Global System for Mobile Communications: originally from Groupe Sp├ęcial Mobile) is the most popular standard for mobile telephony systems in the world.  the world’s most widely used cell phone technology. Cell phones use a cell phone service carrier’s GSM network by searching for cell phone towers in the nearby area.
GSM operates in the 900-MHz and 1800-MHz bands in Europe and Asia and in the 850-MHz and 1900-MHz (sometimes referred to as 1.9-GHz) band in the United States.
it uses TDMA- Time Division Multiple Access:
Narrow band means "channels" in the traditional sense. Each conversation gets the radio for one-third of the time. This is possible because voice data that has been converted to digital information is compressed so that it takes up significantly less transmission space. Therefore, TDMA has three times the capacity of an analog system using the same number of channels. TDMA systems operate in either the 800-MHz (IS-54) or 1900-MHz (IS-136) frequency bands.
CDMA-Code Division Multiple Access:
Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne and CDMA2000 (which are often referred to as simply CDMA), which use CDMA as an underlying channel access method.
CDMA uses a “spread-spectrum” technique whereby electromagnetic energy is spread to allow for a signal with a wider bandwidth. This allows multiple people on multiple cell phones to be “multiplexed” over the same channel to share a bandwidth of frequencies.
With CDMA technology, data and voice packets are separated using codes and then transmitted using a wide frequency range. Since more space is often allocated for data with CDMA, this standard became attractive for 3G high-speed mobile Internet use. While CDMA and GSM compete head on in terms of higher bandwidth speed (i.e. for surfing the mobile Web), GSM has more complete global coverage due to roaming and international roaming contracts.

GSM technology tends to cover rural areas in the U.S. more completely than CDMA. Over time, CDMA won out over less advanced TDMA technology, which was incorporated into more advanced GSM.
3G :
3G is the third generation of mobile phone standards and technology.3G allows simultaneous use of speech and data services and higher data rates (at least 200 kbit/s peak bit rate to fulfill to IMT-2000 specification). Today's 3G systems can offer practice of up to 14.0 Mbit/s on the downlink and 5.8 Mbit/s on the uplink. since the bandwidth is high,greater network capacity and rate of data transfer is also high..
The first pre-commercial 3G network launched in May 2001 by NTT DoCoMo in Japan. The network was branded as FOMA. Following the first pre-commercial launch, NTT DoCoMo again made history with the first commercial launch of 3G in Japan on Oct. 1, 2001.
EDGE-Enhanced Data rates for GSM Evolution 
EDGE  is a backward-compatible digital mobile phone technology that allows improved data transmission rates, as an extension on top of standard GSM. EDGE is considered a 3G radio technology and is part of ITU's 3G definition. EDGE was deployed on GSM networks beginning in 2003— initially by Cingular (now AT&T) in the United States.

4G, which is also known as “beyond 3G” or “fourth-generation” cell phone technology, refers to the entirely new evolution and a complete 3G replacement in wireless communications.
Just as data-transmission speeds increased from 2G to 3G, the leap from 3G to 4G again promises even higher data rates than existed in previous generations. 4G promises voice, data and high-quality multimedia in real-time (“streamed”) form all the time and anywhere.
Various standardization and regulatory bodies estimate the launch of 4G networks commercially between 2012 and 2015.





Today, every human has an extra organ called cell phone... which is of variety of models and size...i say it as organ since it is being with us all around the clock..
 Every one is using it but very few know how it works..
as i said already i love to again knowledge... i put little effort to understand it... here is that...


This is the advanced version of radio,but sophisticated and secured one... As like as the radio each network operator gets their own unique carrier frequency with which they modulate the signals...

  • A cell-phone carrier typically gets 832 radio frequencies to use in a city.
  • Each cell phone uses two frequencies(one to receive and other to transmit) per call -- a duplex channel -- so there are typically 395 voice channels per carrier. (The other 42 frequencies are used for control channels -- more on this later.)      
The carrier chops up the city into cells. Each cell is typically sized at about 10 square miles (26 square kilometers). Cells are normally thought of as hexagons on a big hexagonal grid, like this:

The about 395 channels are divided into 7. each cell has about 56 channels (i.e. 56 people can be talking on their cell phone at a same time). the cell around will not have this same 56 channel.. but the cell outside the cells around the center can have the same this same 56 channel.. this is to avoid the repetition of channel

when the customer goes from one cell to another the signal to the current base station will diminish and the base station of the next cell will find the arrival of other channel with in its range and the two base stations coordinate with each other through the MTSO, and at some point, your phone gets a signal on a control channel telling it to change frequencies. This hand off switches your phone to the new cell.

Let's say you're on the phone and you move from one cell to another -- but the cell you move into is covered by another service provider, not yours. Instead of dropping the call, it'll actually be handed off to the other service provider.this is roaming

once the mobile is switched ON... our mobile will search for same SID(system identification number).. once the same SID is found, it will setup a connection with the base station using the control channels.. else it will say "NO SERVES" or " NO NETWORK COVERAGE"..

our mobile will communicate with base station using the control channels about call set up and channel changing.. for this communication sets up only if our phone system identification number(SID) should match with the base station SID... always there will be a connection between our mobile phone and the base station..with this the mobile telephone switching office(MTSO) will maintain a database of their customers..

once a call arrives.. the MTSO will find the location of the specific customer with the help of the data base.. and divert the call to the nearest base station... then the base station will allocates two frequency(one freq. to receive and another to send the date) which is support by the customer's phone.. then the call will be transferred..

when the customer wants to make a call the reverse operation will be done..

Cell Phone Codes

Electronic Serial Number (ESN) - a unique 32-bit number programmed into the phone when it is manufactured

Mobile Identification Number
(MIN) - a 10-digit number derived from your phone's number

System Identification Code
(SID) - a unique 5-digit number that is assigned to each carrier by the FCC

While the ESN is considered a permanent part of the phone, both the MIN and SID codes are programmed into the phone when you purchase a service plan and have the phone activated.

Hosanna lyrics vinnaithaandi varuvaaaya

The lyrics of the most wonder full............
HOSANNA ........
Yen idhayam udaithaai norungavey

en maruidhayam tharume nee udaikave

Hoooo .... hosanna hosanna
Hoooo .... hosanna hosanna ..

Andha neram andhi neram kanpaarthu kanhdalagi ponaneram edho aache
Oh vaanam thendi vanhdachu appavin thittuellam kaatrodu poye poche
Hosanna en vaasal thandi ponaale
Hosanna verondrum seiyamale
nan aadi pogriren
aval pona pinbu endhan nejai thedipogiren

Ho ...sanna ...
Vazhvukum pakkam vandhen Ho .saana...
savumkum pakkam nindren Ho .saana..
enendral kadhal enben   Ho .saana..

Everybody wanna know be like be like,
I really wanna be here with you..
Is that enough to say that
we are made for each other is all that is *Hosaana* true

Hosaanna... be there when you are calling i will be there..
Hosaanna... be the life the whole life i share..
i never wanna be the same..
its time we re arrange i take a step,
you take a step and me calling out to you...

Helloooo... Hellooooo... Helloooo oooo
Ho.. Hosaanna... Hosaanna..
Ho.... Ho.. Hosaanna... Hosaanna.. Ho... Ho....

Vanna vanna pattu pochi poothedi poothedi
angum ingum alaihindradhey
oh sottu sottai thottu poga
vagam ondru ondruengngo nagarkindrathey
Hosaana - pattu poochi vandhacha ?
Hosaana - megam unnai thottacha ?
Kilinjal aagirai nan kulandhai agiren
nan unnai alli vaithu pothi kolkiren

Helloooo... Hellooooo... Helloooo oooo
Hosaana enmeedu anbu kolla
Hosaana ennodu serdhu sella
Hosaana hmm endru sollum podhu
Ho .. Hosaana....

Yen idhayam udaithaai norungavey
en maruidhayam tharume nee udaikave


here is my second paper with my friennd Rajesh khanna... EMBEDDED BASED AUTO MOBILE COLLISION PREVENTION... this paper is entirely different from my last paper... expect the title everything is on our own... it is completely our paper... we took nearly a weak to complete this paper... while working on this paper we learnt many recent concepts like range finder, how to select controller, braking systems, ABS, etc... it was very enjoyable and interesting to us...
More important is that we won second prize for this in ANNA UNIVERSITY,coimbatore...
here is that interesting paper for you


Most of the automobile accidents could be avoided if the brake had been applied at proper time and at proper distance. In this paper we are using embedded system which could be embedded in the automobile to remove the driver’s reaction time from the situation. The system, consisting of controllers, which analyzes possible accident situations based on the vehicle separation distance, their relative velocity and a static friction coefficient that represents the road conditions. The controller determines the sufficient brake pressure required to prevent collisions while providing a smooth ride for the vehicle’s passengers. 

Our work is to design controller to automate and optimize the application of brake pressure to an automobile’s brakes at proper time. So first requirement implies that the two vehicles should never have any physical contact, while the second one implies that the brakes should be used only in the amount necessary, e.g., they should not undergo large excursions to make small adjustments.

In general, if the automobile in front decelerate, then the vehicle behind it must decelerate to avoid the collision.  Here, the controller tracks the vehicle and have its velocity as reference and applies the appropriate brake pressure at the proper time. So, the controller automatically decelerates to match the velocity of the tracked vehicle and avoid a collision. 

The parameters that we took to avoid collision are
  •  separation between the two vehicles
  • velocity with which they approach each other
  • surface conditions
  For calculating these three parameter, Laser range finders could provide the first two measurements, while wheel-slip sensors currently used for automobile Traction Control Systems or Anti-lock Breaking systems (ABS) could estimate could estimate the third measurement.  

we have three modules, they are
  •       distance finder
  •       intelligent control module
  •       braking system 
here,the distance finder finds the distance between the vehicles and reports to the controller.The controller processes data and  calculates the percentage of braking. this braking is coupled with actual braking of the ABS unit..


"The most incomprehensible about the universe is that it is comprehensible"-ALBERT EINSTEIN
How this universal comes into existence?...Why this universe?... What for?... Why this earth?... Why we are in this world?...How we came in this world?...What,why,when,how.......universe,world,mankind.......?
Many are filled these questions?
Many are trying to give answer for these question?in terms of theories.... so for many theories are proposed and many trying to give new theory for it....But no one gave the exact theory or piratical proof  for it...
One of such theory is Big Bang,which made scientists to accept it... It says before 13.7 billion years, a bang which occurred in the space that created this universe...

Before 13.7 billion years ago, a bang took place... But don't ask what was before the Bang and where the bang is from? it is unknown... a "singularity" of zero volume that nevertheless contained infinite density and infinitely large energy....A bang in  that created this universe...
Less than a billionth of a second after the Big Bang....A bubble much small than an atom appeared... That is universe...with in that bubble 4 natural super forces namely Gravity,Electromagnetic,Strong and weak nuclear force existed in it...suddenly the gravity spited and bubble expanded... then the temperature came down enough to create atoms... hydrogen evolved and then it combined to form helium....after nearly 1 billion years later the stars came and heavier atoms like nitrogen, oxygen and carbon were formed...after nearly 9 billion years later matter and gravity combined to form star...this created pressure, which produced heat.. that gave birth to nuclear fusion and the star was created( That the SUN)....The disk of dust around that star are changed into plants and moon... And the temperature of the 3rd plant,earth helped hydrogen di-oxide(water) to built up here...The chemical reaction took place under the water gave rise to living thing... from which we came(many theories explains how we came in this plant)... At last after 13.7 billions years from the Big Bang i'm typing this.......

and the galaxy is still of the major proof of this theory
What are the major evidences which support the Big Bang theory?
    * First of all, we are reasonably certain that the universe had a beginning.
    * Second, galaxies appear to be moving away from us at speeds proportional to their distance. This is called "Hubble's Law," named after Edwin Hubble (1889-1953) who discovered this phenomenon in 1929. This observation supports the expansion of the universe and suggests that the universe was once compacted.
    * Third, if the universe was initially very, very hot as the Big Bang suggests, we should be able to find some remnant of this heat. In 1965, Radioastronomers Arno Penzias and Robert Wilson discovered a 2.725 degree Kelvin (-454.765 degree Fahrenheit, -270.425 degree Celsius) Cosmic Microwave Background radiation (CMB) which pervades the observable universe. This is thought to be the remnant which scientists were looking for. Penzias and Wilson shared in the 1978 Nobel Prize for Physics for their discovery.
    * Finally, the abundance of the "light elements" Hydrogen and Helium found in the observable universe are thought to support the Big Bang model of origins.  


CERN ,is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. It is situated in the northwest suburbs of Geneva on the Franco-Swiss border, established in1954.
Now, In 30 mar,2010...Their 2nd attempt of Big Bang gave a success result.. They believe that it could give answer for some of the long standing puzzle..Actually they collided two protons in Large Hadron Collider 
(LHC)...LHC is about 27 k.m. long and placed 175 m beneath the ground..This collision gave the result more than the scientists of CERN expected... 

I feel this discussion is incomplete without speaking about GOD.... Who is he?... is there anything else which exists outside of the natural realm?... is there a Architect behind these thing?...Was God the "First Cause"? What was the super natural thing behind everything that had happen, happening and about to happen?..

Being an engineer, I believe in science and not in supernatural... But i won't say there is no GOD.. and pls don't try to prove there is no GOD... Because if someone proves that there is no one called GOD,then suddenly the crime rate will shoot up at lightening speed..many are not involving in crime since they afraid of  GOD...
 so, GOD pls make us to believe that you are watching us and punishing us.... 

F4-Repeat facility

Here is one interesting fact of F4 key...
In MSOFFICE, Use of F4 key will save our time... It will do the same what we did previously before using this F4 key....
Example,when working with word document, we wont concentrate on changing formate while typing... After typing the entire document,we go to the each side heading and we make correspondent change in formate....
Instead of doing change to each side heading separately... just do the formation a single side heading and take our cursor to the next side heading and press F4 key.. It will make a similar change to it...

even, if your deleting a letter form the word "not possible"..After pressing DEL key,it will"ot possible"..then if you press F4 key, it will be "t possible".. again if you press F4 for 2 more times then it will be " possible"...   

In excel, if you are copying a cell content to next 10 cells by clicking and dragging and next if you feeling of copying it to further 10 more cells then just  press F4 key.. it will do the same...

Interesting na?

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Hi everyone,myself Alagappan...electronic and communication engg. student... living in madurai... interested in everything... want to achieve something great in my lifetime...


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