Monday, 15 August 2016

mobile communication


                                                    MOBILE COMMUNICATION
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 In olden days we communicated by smoke signals ,carrier pigeons
what is mobile communication?
      a wireless form of communication in which voice and data information is emitted, transmitted and received via microwaves. This type of communication allows individuals to converse with one another and transmit and receive data while moving from place to place.
some examples: cellular and digital cordless telephones,pagers,air to ground telecommunication and satellite based communications.
what is a mobile?
        A cellular phone is a portable telephone that does not use a wired connection. It connects to a wireless carrier network using radio waves.
what is a mobile phone?
        The mobile phone or cell phone is a long range ,portable electronic device used for mobile communication. In addition to the standard voice function of a telephone, current mobile phones can support many additional services such as SMS for text messaging, email, packet switching for access to the Internet, and MMS for sending and receiving photos and video. Most current mobile phones connect to a cellular network of base stations ,which is in turn interconnected to the public switched telephone network
Inside a cell phone
         parts of a cell phone

  • A microscopic microphone
  • A speaker
  • An LCD or plasma display
  • A keyboard 
  • An antenna
  • A battery
  • An amazing circuit board containing the guts of the phone
main uses of cell phone
   voice calling ,voice mail, E-mail, Messaging, Mobile content, Gaming, Play music, Take photos or video, Download and view images, Shop, Bank, Location based services
cellular fundamentals
    First Generation cellular system

  • Introduction of analog cellular systems in the late 1970s and 1980s
  • analog system
  • incompatible system
  • limited to voice service
  • no encryption
  • FM modulation
  • FDMA transmission technology
  • suffer from capacity saturation

Second Generation cellular system

  • Introduction of digital cellular systems
  • development of unified international standards for mobile communication
  • pan-national roaming
  • digital encryption
  • enhanced range of services
  • low power consumption
  • light weight, compact and pocket size terminals
  • TDMA transmission technology
  • huge capacity

Third generation cellular system


  • Multimedia services 
  • W-CDMA transmission technology
  • large BW
  • Higher bit rate
  • more services
The cellular structure


  • area divided into small zones (cells)
  • cells grouped into clusters
  • this gives less power usage
  • enable frequency reuse
GSM system
components in GSM:
       3 main components 
  1. Mobile station(MS) -UE,SIM
  2. Base Station Subsystem(BSS)-BTS,BSC
  3. Network and Switching Subsystem(NSS)-MSC,VLR,HLR
 MSC is the heart of the GSM Network
 In GSM- 900
Uplink frequency      :890-915MHz
Downlink frequency  : 935-960 MHz









Sunday, 14 August 2016

PHP & MYSQL

PHP is a server scripting language and a powerful tool for making dynamic and interactive web pages. PHP is  a widely - used, free and efficient alternative to competitors such as Microsoft's ASP.
  • PHP is an acronym for "PHP: Hypertext Preprocessor"
  • PHP is a widely-used, open source scripting language
  • PHP scripts are executed on the server
  • PHP is free to download and use
Basic PHP Syntax:
A PHP script can be placed anywhere in the document.

A PHP script starts with <?php and ends with ?>:
<?php
//php code goes here
?>
The default file extension for PHP files is ".php".
A PHP file normally contains HTML tags, and some PHP scripting code.
Below, we have an example of a simple PHP file, with a PHP script that uses a built-in PHP function "echo"  used to get output on a web page:
<html>
<body>
<h1>My first page</h1>
<?php
echo"Good Morning GPT Addanki";
?>
</body>
</html>

PHP supports the following data types:
  • String
  • Integer
  • Float (floating point numbers - also called double)
  • Boolean
  • Array
  • Object
  • NULL
  • Resource
With PHP  you can connect to and manipulate databases.
MySQL is the most popular database system used with PHP.
  • MySQL is a database system used on the web
  • MySQL is a database system that runs on a server
  • MySQL is ideal for both small and large applications
  • MySQL is very fast, reliable, and easy to use
  • MySQL uses standard SQL
PHP-AJAX

AJAX = Asynchronous JavaScript and XML.
AJAX is a technique for creating fast and dynamic web pages.
AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.
Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.
Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs.

AJAX FLOW CHART

AJAX