Technology Facts

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Bluetooth 1. Why is Bluetooth called a cable replacement technology? - Bluetooth technology allows the creation of Personal Area Networks without cables or wires that are usual in home networks.

2. Give a generic description of Bluetooth? - Bluetooth is a low-cost, short-range (RF) links between mobile PCs, mobile phones 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.

and other portable devices. Bluetooth can transmit through solid, non-metal objects. Why can Bluetooth equipment integrate easily in TCP/IP network? - Because Bluetooth uses wireless LAN standards IEEE for data transmission. Is it possible to connect multiple Bluetooth hubs? - No, only one hub can be used at a time with a computer. USB or Serial devices can be added. What is FCC and how does it relate to Bluetooth? - FCC is Federal Communication Commission, which issues licenses to the stations for specific frequencies. It also decides who is able to use which frequency for what purpose. Since Bluetooth is using unlicensed spectrum, FCC has no direct involvement with Bluetooth Under what frequency range does Bluetooth work? - 2.45 GHz is the frequency range. Do Bluetooth devices need line of sight to connect to one another? - No. Which technology is used in Bluetooth for avoiding interference? - Frequency hopping is the technology used in Bluetooth. Bluetooth signals do not interfere with our PCs or cordless phones or portables. Why? - Bluetooth uses low-power signals, it plays around in 2.45 GHz range, while most of consumer devices would be using 900 MHz. What is Airport? - Airport is a wireless communications system, like Bluetooth. It is based on the IEEE 802.11 recommendation. It also uses 2.4 GHz frequency band, but its range is about 45 meters and it boasts a transmission speed of 11 Mbit/second. It is developed by Lucent Technologies. What is Piconet? - A collection of devices connected through Bluetooth technology in an ad hoc fashion. What are the three main types of connection used by Bluetooth? - Single slave, Master slave, Scatternet . What is FEC in Bluetooth? - Forward Error Correction is a method by which Bluetooth increases its noise immunity. FEC is a method that enables a receiver to not only detect, but also correct errors in a transmission. Which method is primarily used for Voice transfer? - Synchronous Connection Oriented (SCO) is a method primarily used for Voice transfer. What is the frequency range used for Bluetooth in Europe and United States? - 2402 MHz to 2480 MHz are the frequency ranges used in USA and Europe. List some Technology characteristic of Bluetooth? - Omni directional, Adaptive output power to minimize interference, Support Synchronous & asynchronous services, Fast Frequency Hopping to avoid interference, Short data packets to maximize capacity during interface. Which company originally conceived and developed Bluetooth? - Ericsson.

18. How does Bluetooth use frequency hopping for security? - Bluetooth picks a random frequency out of 79 and then hops around the range about 1600 times per second.

19. What is a Bluetooth dongle? - A device that hangs outside of a computer, or phone to provide Bluetooth connection. 20. What are the other (competing or not) wireless technologies? - Wi-Fi, IrDa, EDGE, UWB (Ultra Wide Band) 21. Which Bluetooth version uses adaptive frequency hopping? Why? - In Version 1.2 Adaptive frequency hopping method is 22. 23. 24. 25. 26.

used, which improves resistance to radio interference, and provides higher transmission speed. How many SCO links are there in a piconet? - In a piconet, there can be up to three SCO links of 64,000 bits per second each. what is the total number of masters and slaves in a piconet? - 1 Master and 7 Slaves. Which method is used for Data transfer? - Asynchronous Connectionless (ACL) is Data transfer method in Bluetooth What is the frequency range used for Bluetooth in Japan? - 2472 to 2497 MHz is the frequency range used for Bluetooth in Japan. What is the strength of the signal transmitted by powerful cell phones? - The powerful cell phones can transmit a signal of 3 watts.

8086 questions 1. What are the flags in 8086? - In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Interrupt 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

flag, Direction flag, and Sign flag. What are the various interrupts in 8086? - Maskable interrupts, Non-Maskable interrupts. What is meant by Maskable interrupts? - An interrupt that can be turned off by the programmer is known as Maskable interrupt. What is Non-Maskable interrupts? - An interrupt which can be never be turned off (ie.disabled) is known as Non-Maskable interrupt. Which interrupts are generally used for critical events? - Non-Maskable interrupts are used in critical events. Such as Power failure, Emergency, Shut off etc., Give examples for Maskable interrupts? - RST 7.5, RST6.5, RST5.5 are Maskable interrupts Give example for Non-Maskable interrupts? - Trap is known as Non-Maskable interrupts, which is used in emergency condition. What is the Maximum clock frequency in 8086? - 5 Mhz is the Maximum clock frequency in 8086. What are the various segment registers in 8086? - Code, Data, Stack, Extra Segment registers in 8086. Which Stack is used in 8086? - FIFO (First In First Out) stack is used in 8086.In this type of Stack the first stored information is retrieved first. What are the address lines for the software interrupts? -

RST 0

0000 H

RST1

0008 H

RST2

0010 H

RST3

0018 H

RST4

0020 H

RST5

0028 H

RST6

0030 H

RST7

0038 H

12. What is SIM and RIM instructions? - SIM is Set Interrupt Mask. Used to mask the hardware interrupts. RIM is Read Interrupt Mask. Used to check whether the interrupt is Masked or not.

13. Which is the tool used to connect the user and the computer? - Interpreter is the tool used to connect the user and the tool. 14. What is the position of the Stack Pointer after the PUSH instruction? - The address line is 02 less than the earlier value. 15. What is the position of the Stack Pointer after the POP instruction? - The address line is 02 greater than the earlier value. 16. Logic calculations are done in which type of registers? - Accumulator is the register in which Arithmetic and Logic calculations are done.

17. What are the different functional units in 8086? - Bus Interface Unit and Execution unit, are the two different functional units 18. 19. 20.

in 8086. Give examples for Micro controller? - Z80, Intel MSC51 &96, Motorola are the best examples of Microcontroller. What is meant by cross-compiler? - A program runs on one machine and executes on another is called as cross-compiler. What are the address lines for the hardware interrupts? 003C H

RST 7.5 RST 6.5

0034 H

RST 5.5

002C H

TRAP

0024 H

21. Which Segment is used to store interrupt and subroutine return address registers? - Stack Segment in segment register is used to store interrupt and subroutine return address registers.

22. Which Flags can be set or reset by the programmer and also used to control the operation of the processor? - Trace 23. 24. 25.

Flag, Interrupt Flag, Direction Flag. What does EU do? - Execution Unit receives program instruction codes and data from BIU, executes these instructions and store the result in general registers. Which microprocessor accepts the program written for 8086 without any changes? - 8088 is that processor. What is the difference between 8086 and 8088? - The BIU in 8088 is 8-bit data bus & 16- bit in 8086.Instruction queue is 4 byte long in 8088and 6 byte in 8086.

8085 questions 1. What are the various registers in 8085? - Accumulator register, Temporary register, Instruction register, Stack Pointer, Program 2. 3. 4. 5.

6. 7. 8. 9.

Counter are the various registers in 8085 . In 8085 name the 16 bit registers? - Stack pointer and Program counter all have 16 bits. What are the various flags used in 8085? - Sign flag, Zero flag, Auxillary flag, Parity flag, Carry flag. What is Stack Pointer? - Stack pointer is a special purpose 16-bit register in the Microprocessor, which holds the address of the top of the stack. What is Program counter? - Program counter holds the address of either the first byte of the next instruction to be fetched for execution or the address of the next byte of a multi byte instruction, which has not been completely fetched. In both the cases it gets incremented automatically one by one as the instruction bytes get fetched. Also Program register keeps the address of the next instruction. Which Stack is used in 8085? - LIFO (Last In First Out) stack is used in 8085.In this type of Stack the last stored information can be retrieved first. What happens when HLT instruction is executed in processor? - The Micro Processor enters into Halt-State and the buses are tri-stated. What is meant by a bus? - A bus is a group of conducting lines that carriers data, address, & control signals. What is Tri-state logic? - Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tri-state logic has a third line called enable line.

10. Give an example of one address microprocessor? - 8085 is a one address microprocessor. 11. In what way interrupts are classified in 8085? - In 8085 the interrupts are classified as Hardware and Software interrupts. 12. What are Hardware interrupts? - TRAP, RST7.5, RST6.5, RST5.5, INTR. 13. What are Software interrupts? - RST0, RST1, RST2, RST3, RST4, RST5, RST6, RST7. 14. Which interrupt has the highest priority? - TRAP has the highest priority. 15. Name 5 different addressing modes? - Immediate, Direct, Register, Register indirect, Implied addressing modes. 16. How many interrupts are there in 8085? - There are 12 interrupts in 8085. 17. What is clock frequency for 8085? - 3 MHz is the maximum clock frequency for 8085. 18. What is the RST for the TRAP? - RST 4.5 is called as TRAP. 19. In 8085 which is called as High order / Low order Register? - Flag is called as Low order register & Accumulator is called as High order Register.

20. What are input & output devices? - Keyboards, Floppy disk are the examples of input devices. Printer, LED / LCD display, CRT Monitor are the examples of output devices.

21. Can an RC circuit be used as clock source for 8085? - Yes, it can be used, if an accurate clock frequency is not required. Also, the component cost is low compared to LC or Crystal.

22. Why crystal is a preferred clock source? - Because of high stability, large Q (Quality Factor) & the frequency that doesn’t drift with aging. Crystal is used as a clock source most of the times.

23. Which interrupt is not level-sensitive in 8085? - RST 7.5 is a raising edge-triggering interrupt. 24. What does Quality factor mean? - The Quality factor is also defined, as Q. So it is a number, which reflects the lossness of a 25.

circuit. Higher the Q, the lower are the losses. What are level-triggering interrupt? - RST 6.5 & RST 5.5 are level-triggering interrupts.

OSI The OSI Model is used to describe networks and network application. Layers of OSI Model Three are Sever Layers of OSI Model : OSI Layer Diagram: 7) Application Layer : The application layer provider different services to the application. Example of services provided by this layer are file transfer, electronic messaging e-mail, virtual terminal access and network management.

6) Presentation Layer : The Presentation layer is responsible for protocol conversion, date encryption/decryption, Expanding graphics command and the date compression. This layer makes the communications between two host possible. 5) Session Layer : This layer is responsible for establishing the process-to-process communication between the host in the network. This layer is responsible for establishing and ending the sessions across the network. The interactive login is an example of services provided by this layer in which the connective are re-connected in care of any interruption. 4) Transport Layer : This layer is responsible for end-to-end delivers of messages between the networked hosts. It first divides the streams of data into chunks or packets before transmission and then the receiving computer re-assembles the packets. It also guarantee error free data delivery without loss or duplications. 3) Network Layer : This layer is responsible for translating the logical network address and names into their physical address ( MAC address). This layer is also responsible for addressing, determining routes for sending and managing network problems such as packet switching, data congestion and routines. 2) Data Link Layer : Data link layer is responsible for controlling the error between adjacent nodes and transfer the frames to other computer via physical layer. Data link layer is used by hubs and switches for their operation. 1) Physical Layer : Physical Layer is responsible for transmitting row bit stream over the physical cable. The physical layer defines the hardware items such as cables, cards, voltages etc. How to remember the layer of OSI model? The easiest way to remember the different layers of OSI Model is to use the mnemonic "All people seem To need Data Processing": Layer Name Mnemonic 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical

WIMAX

All People Seem To Need Data Processing

Introduction What is WiMAX? Simply put WiMAX is, Worldwide Interoperability for Microwave Access, a technology standard that enables high speed wireless internet. In other words, WiMAX combines the high speed of a broadband connection with the convenience of mobile internet connectivity. WiMAX provides wireless broadband access up to a radius of 50 kilometers (30 miles) for fixed receivers and 5-15 kilometers (3-10 miles) for mobile receivers.

How does WiMAX work? WiMAX needs setting up of a tower to establish microwave connections with the users. This operates in the same way as a cell phone tower. In the case of WiMAX, the tower is connected to internet through a high speed cable like a T3 line. The difference from broadband is that here the bandwidth does not have to be divided using wires. WiMAX is in a way an advanced version of WiFi, a similar technology. Whereas WiFi allows a network within a radius of 30-100 meters (100-300 feet), WiMAX connectivity can be extended over a radius of up to 50 kilometers. This high speed data transfer over a much larger area is made possible by lessening interference using the IEEE 802.16 Air Interface Standard. Currently WiMAX operates on both licensed and non-licensed frequencies. Advantage and Applications As it is possible to use WiMAX over longer distances, this technology may come in handy in creating city wide networks. It is also better suited than WiFi for large area public places like airports, college and university campuses and large office set ups. It also provides for greater mobility to users. This way WiMAX may be a good option for people on the move using gadgets like laptops, iPods and PDAs. As WiMAX follows a point-to-multipoint architecture, it is an ideal solution for delivering broadband to places where it would not be viable to establish wired connections. Rural areas and high rises are examples for this situation. Currently this last mile part of the connectivity is the biggest stumbling block to broadband providers, in terms of cost and manpower requirements. WiMAX can bring down the costs and subsequently make internet connectivity cheaper to the end user. Another advantage over some other wireless technologies is that WiMAX does not need a direct line of sight between the source and the receptor. It also has a comparatively high shared data rate at 70Mbps, which is good enough to reach about a thousand homes. WiMAX is also an excellent saver of time. As it does not need cables to connect with the receptors, it is possible to establish connection to an entire campus or even city in a matter of a few days.

WiMAX also allows for greater convergence of diverse applications such as fixed and mobile telephony, apart from entertainment sectors like television. Challenges That said, WiMAX need not come to eliminate wired connectivity altogether. In areas where wired broadband is already established, DSL still reigns supreme. Thus it is more likely that WiMAX will develop as a complementary to wired connectivity. Secondly, the real potential of WiMAX is in the possibility of bringing diverse services such as telephony, mobile television and broadband internet under its umbrella. This requires that players from these different fields work together to provide single point service to the end user. Consumer billing and mutual settlement systems have to be extremely efficient to handle these requirements.

VOLP HISTORY Introduction VoIP stands for Voice over Internet Protocol. This phenomenon has made a profound change in the world of telephone communications. The traditional method of making calls the landlines are being fats replaced by this technology that has taken the world by storm. Not only is this method economical as this does not involve the telephony company charges that are pretty heavy, it also gives you better coverage. This works through the broadband and uses the World Wide Web to route its calls. The best thing about it is that the person who you are calling through the internet phone need not necessarily have it also to receive your call. A technology that has brought a revolution in our worlds at least deserves that we look into its history. What I promise you is that if you find its history exciting then you will find its future more intriguing and exciting. The roots of Internet phone service or VoIp goes back to 1995 when a small telecom company called Vocaltec released its first Internet phone software. The software had been designed for a home Pc and used similar attachments like headsets, microphones, sound cards and speakers. This software called ‘Internet Phone’ used the H.323 protocol instead of the currently prevalent SIP protocol. This software was very well accepted in the market and by 1996 Vocaltec had a successful IPO running. The position that SKYPE occupies in the market was then occupied by Vocaltec. The draw back because of which this software suffered was the non availability of broadband and a resultant poor voice quality owing to modems. The voice quality was worse than the normal phone calls. However the advancement of technology cannot be denied and it was a big leap forward. An employee of Vocaltec is also amongst the founders of Whichvoip.com 1998 saw VoIP traffic making about 1% of the total voice traffic in the United States. The heat was soon on and companies were head bent in creating softwares to enable PC to phone and phone to phone connections.

WHAT IS VOLP????????????? Introduction In this section you will learn about VoIP and its importance in today's scenarios. Why VoIP is so popular on the internet?

VoIP- What is VoIP? VoIP is a technology for sending and receiving voice single over Internet Protocol (IP). Using VoIP users can call to some other VoIP user without using the PSTN( public-switched telephone network). Any VoIP system consists of both hardware and Software. these hardware and software together enables the user to make telephone calls via Internet. VOIP technology user IP network to send the voice single in the form of data packets. To do this, it first converts the voice signals into data packets and then send. The major benefit of VOIP and Internet telephony is that if avoids the tolls charged by ordinary telephone service. VOIP is so beneficial that is saves hundreds or even thousand of dollars if used extensively. That is the reason behind VOIP Popularity. Many Companies are using VoIP for communication and saving thousands of dollars. Benefits of VoIP: VoIP provides wondered benefits to both corporate and individual users. Its grate technology of this time and it can provide huge benefits in many ways. VoIP can provide benefits to the web-enabled call centers, remote telecommuting, collaborative meetings etc.. and it even provides benefits to the individual users. Following list will give you an idea about the VoIP benefits: •

Significant Cost Savings: The cheap call is one of the main advantage of VoIP phones. Business can save over 30% to even 90% calling costs. Beside the cheap calls it other advantage also, you can integrate you phone and data networks together and increase the maintainability of the network.

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Grate mobility: You can take your VoIP phone with you anywhere in the world.

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Many facilities: VoIP phone provides Voice Mail, Caller ID, Call Conferencing, Call Forwarding, Long distance calls and many more benefits.

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Can be used on computers: VoIP can be configured on computer and easily used.

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Wireless Enabled: VoIP system can also work on the wireless network like Wi Fi and blue tooth.

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Scalability: In comparison to the Traditional PBX phone systems, VoIP system provides grater stability as you can run a number of ‘virtual users’ through each network socket.

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Less Operation Cost: If you use the software based VoIP system, you can use the existing hardware (computer) to enable the calling.

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Enhance Calling: You can even send documents along with you voice messages.

WI-FI Introduction WiFi is a globally used wireless networking technology that uses the 802.11 standard. The term WiFi is an abbreviation of ‘wireless fidelity’. The technology used in WiFi was developed in 1997 by the Institute of Electrical and Electronics Engineers (IEEE). This technology was later commercialized by the Wi-Fi Alliance, a trade group. What Happens? The basic system of WiFi is very simple. In a WiFi enabled network, computers with WiFi cards connect wirelessly to an access point or router. This access point or router is internet enabled the usual way, connected to the internet using a cable or DSL modem. Any PC or laptop with a WiFi card, which is within a radius of 200 feet (60 meters) from the access point can access internet. However a distance of 100 feet (30 meters) is considered ideal for good quality access. An area surrounding an access point, providing wireless access, is called a wireless hotspot. The Technology The technology used in WiFi is easiest to understand in terms of radio. It is quite similar to walkie-talkies, the only difference being in the strength of signals. An ordinary walkie-talkie can handle only limited data in the range of 1000 bits per second, and operate at 49 MHz. In

the case of WiFi radios, the signal strength is much more, so they can handle much higher data rates. WiFi radios typically operate at a frequency of 2.4GHz. There are three versions of WiFi radios currently available- the ones that work with 802.11b, 802.11g and 802.11a standards. While the first two- 802.11b and 802.11g- transmit 2.4 GHz, the radios operating at 802.11a standard can transmit at 5GHz. Another important feature of the WiFi radios that enables higher data rates is the coding techniques used. The 802.11a and 802.11g standard radios use Orthogonal Frequency-Division Multiplexing (OFDM) technique while the 802.11b uses Complementary Code Keying (CCK) technique. Due to the higher frequencies and the encoding techniques, WiFi radios can transmit a very high amount of data per second. The 802.11a and 802.11g standard radios transfer between 30-54 megabits per second and the 802.11b standard typically conveys 7-11 megabits per second. The WiFi Alliance has developed certification standards for laptops and other electronic gadgets like PDAs. Most of these appliances are today WiFi certified. This means that these gadgets are interoperable regardless of the brand. The Benefits The technology of WiFi was developed to enhance the convenience and increased productivity that portable computing and communication systems ushered in. In today’s scenario, the workforce moves about a lot on business. They typically carry laptops, PDAs and other gadgets and need to access the office network from wherever they are. WiFi is a hassle-free, cost effective and quicker way of deploying a network. It also makes greater flexibility possible. A WiFi enabled work environment helps workers to stay connected for longer and even interact with the co-workers effortlessly. Security- The Risk Factor A wireless access point has the risk that anyone can access the information if they get within an accessible distance. Therefore it is important to take security precautions while setting up a WiFi network in your organization. The degree of security depends on the nature of information your organization handles. If it is highly sensitive information, you will need to go for customized security measures. Introduction WiFi, the short form of Wireless Fidelity, is a technology that allows you to connect to the internet without a cabled network. WiFi technology uses the 802.11 standard developed by the Institute of Electrical and Electronics Engineers (IEEE) and commercialized by the WiFi Alliance.

Whether you are at home, your office cabin or another business location, using WiFi you can access the internet from your laptop or PDA as long as you are within the range of a WiFi access point. What Happens WiFi uses radio technology for communication, and mostly operates at 2.4 or 5 GHz frequency. Most of the new connectible devices are today WiFi certified, which means not only that they are WiFi enabled, but also that these devices are interoperable. In a WiFi network, computers with a WiFi network card can connect wirelessly to a WiFi router. The router is connected to internet using a cable or DSL modem. Any WiFi enabled connectible device within 60 meters or so of the access point can access the internet. Some WiFi hotspots are open in the sense that anyone with a connectible device within the range can access them, while some others are closed which means that only authorized users can access them using a password. Where WiFi can Help Interoperability is one big advantage of WiFi. WiFi allows users to connect with internet as well as with each other and other devices. It also helps you transcend the distance imitations of using cables and also saves some of the cost. WiFi technology is of special advantage to people in marketing and sales as these sectors involve a lot of travel. In fact WiFi can help anyone who has to move about a lot on work. They can access their work email or company databases from wherever they are using WiFi technology. Thus WiFi technology allows businesses to grow and expand fast. Further, businesses do not have to throw away their existing network infrastructure to start on WiFi. It is very easy to integrate WiFi into your current wired network. This gives WiFi a definite cost advantage. As we saw earlier WiFi technology uses the 2.4-5 GHz bandwidth and speeds ranging from10 to 50 Mbps. This is quite comparable to the speed of a T1 line. Security All said and done, security is one of the biggest issues with a wireless network. This is all the more relevant in the case of a plug and play technology like WiFi. If you are not careful enough, anyone close enough to your base station can intercept the data you send and receive from your network or break into your system. Therefore it is important to take sufficient security measures when you set up a WiFi hotspot at your home or office. Security is also applicable when you need to access a public hotspot using your laptop or other devices.

WHAT IS HSDPA?????????????? Introduction HSDPA is an acronym for High Speed Downlink Packet Access which is an advanced protocol for mobile telephone data transmission. HSDPA is an evolved form of W-CDMA (Wideband Code Division Multiple Access) technology. HSDPA promises to provide download speeds equivalent to an ADSL (Asymmetric Digital Subscriber Line) line on your mobile phone. The technology standard used in HSDPA is called 3.5G. The Technology As we saw, the 3.5 G standard used in HSDPA is an improvement upon the 3G protocol used in W-CDMA technology. With HADPA, the data transfer rate improves over W-CDMA by a factor of at least five. Theoretically speaking, it is possible to reach data transmission speeds of 8-10 Mbps with HSDPA. Therefore HSDPA is touted as highly favorable for transmission areas like video and streaming music where high data transfer rates are required. Now the question is, in what way HSDPA has improved upon WCDMA. HSDPA employs different techniques for modulation and coding by creating a new channel within W-CDMA. This channel is called High Speed Downlink Shared Channel, or HS-DSCH. This channel is created in such a way that it makes higher downlink speeds possible. However this channel enables only downlinks, which means that the source can send data to the receptor but not vice versa. You cannot send data from your phone to the source using HSDPA. The HS-DSCH channel is shared among users, allowing the most efficient use of radio signals and thus helping faster download speeds. HSDPA uses 5 MHz bandwidth. The technology upgrade has enabled a smooth transition for Universal Mobile Telecommunications System (UMTS). In the HS-DCH channel, the variable spreading factor and fast power control of the WCDMA channels are done away with. The new technology uses Adaptive Modulation and Coding (AMC), fast packet scheduling at the Base Station and fast retransmissions from the Base Station. The retransmissions are done through Hybrid Automatic Repeat Request (HARQ), where the concept of incremental redundancy comes into play. Here, the retransmissions have different codes of the data against the codes of the original transmission. In other words, the data received at the base station is ‘processed’ to manage any corruption the data may have gone through at the time of the original transmission. The net result of this process is that the user device can receive error free packets, thus ensuring better quality to the video and sound. Is HSDPA Here to Stay? Well, only time can answer that question. Many mobile telecommunication companies are working to deploy 3G (WCDMA) networks and this is a positive indication. It would be easy to upgrade to 3.5 G once a 3G network is in place. Some companies are expected to deploy HSDPA by the end of 2006. However the downlink speeds in reality at this moment are going to be much lower at 1.8-3.6 Mbps, than the theoretical potential of 8-10 Mbps.

The success of HSDPA will also depend on many other factors. There are other technologies like CDMA2000, 1xEV-DO and WiMAX that promise high data transmission speeds. Further, HSDPA is an improvement upon the W-CDMA standard, so it can gain acceptance only in places where W-CDMA has been deployed successfully.

What is Ajax - Asynchronous JavaScript and XML This section explains you the Ajax. You will learn the basics of Ajax. Ajax is of the most important technologies for the development of highly interactive web application and due to its features it have become extremely popular these days. What is Ajax? Asynchronous JavaScript and XML or Ajax for short is new web development technique used for the development of most interactive website. Ajax helps you in making your web application more interactive by retrieving small amount of data from web server and then showing it on your application. You can do all these things without refreshing your page. Usually in all the web applications, the user enters the data into the form and then clicks on the submit button to submit the request to the server. Server processes the request and returns the view in new page ( by reloading the whole page). This process is inefficient, time consuming, and a little frustrating for you user if the only the small amount of data exchange is required. For example in an user registration form, this can be frustrating thing for the user, as whole page is reloaded only to check the availability of the user name. Ajax will help in making your application more interactive. With the help of Ajax you can tune your application to check the availability of the user name without refreshing the whole page. Understanding the technology behind Ajax Ajax is not a single technology, but it is a combination of many technologies. These technologies are supported by modern web browsers. Following are techniques used in the Ajax applications. •

JavaScript: JavaScript is used to make a request to the web server. Once the response is returned by the webserver, more JavaScript can be used to update the current page. DHTML and CSS is used to show the output to the user. JavaScript is used very heavily to provide teh dynamic behavior to the application.

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Asynchronous Call to the Server: Most of the Ajax application used the XMLHttpRequest object to send the request to the web server. These calls are Asynchronous and there is no need to wait for the response to come back. User can do the normal work without any problem.

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XML: XML may be used to receive the data returned from the web server. JavaScript can be used to process the XML data returned from the web server easily.

How Ajax Works? When user first visits the page, the Ajax engine is initialized and loaded. From that point of time user interacts with Ajax engine to interact with the web server. The Ajax engine operates asynchronously while sending the request to the server and receiving the response from server. Ajax life cycle within the web browser can be divided into following stages: •

User Visit to the page: User visits the URL by typing URL in browser or clicking a link from some other page.

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Initialization of Ajax engine: When the page is initially loaded, the Ajax engine is also initialized. The Ajax engine can also be set to continuously refresh the page content without refreshing the whole page.

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Event Processing Loop: * Browser event may instruct the Ajax engine to send request to server and receive the response data * Server response - Ajax engine receives the response from the server. Then it calls the JavaScript call back functions * Browser (View) update - JavaScript request call back functions is used to update the browser. DHTML and css is used to update the browser display.

Benefits of Ajax Ajax is new very promising technology, which has become extremely popular these days. Here are the benefits of using Ajax: •

Ajax can be used for creating rich, web-based applications that look and works like a desktop application

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Ajax is easy to learn. Ajax is based on JavaScript and existing technologies like XML, CSS, DHTML. etc. So, its very easy to learn Ajax

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Ajax can be used to develop web applications that can update the page data continuously without refreshing the whole page

What are GPS Tracking Systems? Introduction The technological advances of the last decade have brought about hitherto unimagined changes in the way we go about our lives. The most remarkable of these changes has been the way we communicate- at work, in our personal lives and in the media. Never has it been so easy to communicate with others, no matter which part of the world they are in. Apart from interpersonal communications, the Internet

and satellites have enabled us to keep track of people, places and things in the most remote parts of the world, 24/7. GPS or Global Positioning System is a major technology drive on this front. Origins GPS technology was initially developed in the United States for defense purposes. GPS uses satellite technology for its navigation system. The GPS navigation system can track a person or object fitted with GPS equipment irrespective of which part of the globe they’re in. The tracking range is quite accurate with a usual error range of about 100 meters. Further, the GPS bandwidth is available for free. GPS Solutions There is a wide range of GPS based tracking devices available today, that cater to different requirements. GPS specialist companies work with businesses to provided customized tracking systems for the specific requirements of each particular business.

Global Positioning System Brief History :-The Global positioning System (GPS), formally known as the Navstar Global Positioning System, was first time used by united states to enhance the effectiveness of their allied military forces in 1973. GPS was designed for dual use purpose. Now days GPS is being very popular as it is emerging as a Global Information Infrastructure for illustrating maps and surveying to international air traffic management and automatic vehicle location (AVL). Components:- GPS has three separate individual components, which works together to perform the task as a unit. These are: 1. Space Segment. 2. Control Segment 3. User Segment Space Segment:- Twenty four separate individual satellites situated in their own orbit above 11,000 nautical miles from the earth consists space segment. Control Segment:-Control segment component is the control station which works to check out the functions of satellite, whether these are properly working or not. There are only five control stations situated in the entire world. User Segment:- This component is made for the user. User can hold it in it’s hand or it can be mounted in the car. It works as a receiver. How GPS works:- GPS is used for tracing the exact position any time, any day, in any weather, anywhere on the earth. It is very accurate within 25 feet or less. Though it is said that it can works with accuracy within 150 feet or less. The tracking satellites of GPS works 24*7*365 means continuous signalling towards the earth, which can be traced anywhere, if there is it’s receiver component is present or it can point out the person who have it’s receiver component part. These satellites are continuously monitored by their control stations situated around the world.

Utility of GPS in Defense:- The Military forces of United States generally used it as a powerful means to get the exact location before beginning the functioning of all the satellites. Now they are using it for all the military operations and weapon systems. They are also using it for getting highly accurate orbit data and controlling spacecraft orientation. Uses of GPS in daily life:- Now days GPS technology is also being used in daily life besides military forces. There are following areas, in which it is being used: Fleet Vehicle Management:- Fleet vehicle management system is also known as Automatic vehicle locator (AVL), in which commercial and private trucking companies use it for tracking their cars, trucks, buses and other equipment to check it out whether these are following the appropriate route and condition according to contract signed by the transport owner and the customer. Emergency Management:- GPS technology is very helpful for Police, Fire Brigade, emergency medical service units as they can find the exact location and can control over the situation before being beyond the limit. Police car, Fire truck or Ambulance can find the shortest route to reach to the destination point. Consumer Vehicle:- GPS technology is also very helpful for recovery of theft vehicle, in which GPS system is enabled. Police can find it easily due to receiver; the user component part is applied in it. Wildlife Management:- Scientist uses this technique for the counting of the wild animals especially endangered species like Tiger, Panda Bear, Elephant etc. Engineering:- Civil engineers used this technique for making tunnels, bridges etc. For example:- Britain and France used this technique for constructing a tunnel connecting both of them. Like this, there are many more fields in which it’s utilization has been increasing day by day. The future of this technology is unlimited.

How GPS Works? Introduction GPS or Global Positioning System is a technology for locating a person or an object in three dimensional space anywhere on the Earth or in the surrounding orbit. GPS is a very important invention of our time on account of the many different possibilities it brings. The technology is still involving and new applications are being developed to make full use of its potential. The Idea behind GPS The GPS system works with the help of a satellite network. Each of these satellites broadcasts a specific signal quite like a normal radio signal. These signals that carry the location data are received by a low cost aerial which is then decoded by the GPS software. The software is able to identify the satellite, its location in space and the time the signals take to travel from each satellite. The software then processes the information it receives from each satellite to calculate the position of the receiver. The overall process is quite like traditional navigation methods. If you can draw lines from three predefined places on the map to where you are, you can identify your position on map as the intersection of these lines, within a margin of error.

Error Rectification As we saw earlier, there are a number of factors that prevent absolute accuracy in locating the receiver. One major reason is that it is impossible to achieve perfect synchrony between the clocks in all the satellites and the GPS receiver. The satellites have atomic clocks which are very accurate by themselves and with respect to each other. But it is not possible to fit the GPS units with atomic clocks as atomic clocks are very expensive, and this is what usually causes time errors. However the GPS system has been designed to account for any error element due to the time factor. A fourth satellite is brought into the picture for cross checking the process. This enables the software to rectify not only any discrepancy in the calculations, but also any inaccuracy of its own clock. GPS and Mapping GPS by itself helps us only to know where the device is in space. However this has to be combined with mapping for many of the practical applications of GPS. The mapping part enables the user to work out possible routes and plan trips in advance. It is often this mapping component that adds to the price of a GPS package. The mapping data has to be accurate and be updated often. There are different kinds of maps for different users and kinds of needs. For instance, road users need maps that give accurate information about the road network in the region where they travel. However their maps need not contain information such as the height of hills. On the other hand people who use GPS for hiking need a detailed map of the terrain with rivers, hills, tracks and trails. Similarly what marine users need is information about sea bed, navigation channels and such maritime data. GPS is also used for fishing purposes like tracking shoals of fish and predicting their movements. This has huge benefits for cooperative fishing. The several boats in a group can relay their location and information about where they find the best fishing waters. There are special GPS packages called fish-finders for this purpose. Fish-finders have additional features like sonars, advanced tracking functions as well as data storage capacities. An Overview of Consumer GPS Devices The consumer range of GPS solutions start with sophisticated car GPS systems- they can have features like voice guiding, dynamic route calculation and in built features to load and update a map from a CD. The handheld range includes GPS devices from companies such as Magellan and Garmin. These typically have maps stored inside and work well for outdoor use. However the handheld range does not usually have dynamic route calculation facility and so the user has to find his/her route.

Another application that was launched in the market recently has GPS working in a PDA. The PDA is designed to connect with a GPS receiver. This range is generally cheap, but the PDA based application is not very rugged. There are also variants that use wireless Bluetooth connections. These can work both for personal navigation as well as inside a vehicle.

What is WAAS? Introduction WAAS or Wide Area Augmentation System is a system of satellites and ground stations that work with GPS to improve the quality of signals and rectify errors. The quality of the signals can be up to five times better with WAAS. A GPS receiver with WAAS can give a position accuracy of within three meters. Further, WAAS does not need additional equipment or service fees.

Why WAAS The WAAS system has been developed by the Federal Aviation Administration (FAA) and the Department of Transportation (DOT) jointly for use in precision flight approaches. GPS alone is not sufficient to meet the accuracy levels FAA requires. WAAS was therefore developed to account for signal errors due to ionosphere disturbances, time errors, and satellite orbit errors. WAAS is also vital in getting information about the health of each satellite in the GPS network. How WAAS Works The WAAS system is made up of about 25 ground stations across the United States, that act as reference points to monitor the GPS satellite data. Of these 25 stations two stations, located on the East and West coasts respectively, gather data from the other stations and create the correction message. The correction takes into account the clock and orbit errors as well as delays caused by atmospheric disturbances. The corrected message then goes to a geostationary satellite (geostationary satellites are satellites with a fixed position over the equator) which then relays it to GPS receivers. These signals can be read by all WAAS enabled GPS receiver. Who Benefits from It The WAAS coverage is currently confined to North America. Further areas with tall trees and mountains may not be able to receive the WAAS signals. WAAS signals are easy to receive for open land and marine applications. An advantage WAAS has over differential GPS system is that WAAS gives coverage both inland and offshore whereas DGPS is entirely land-based. Further, unlike DGPS, WAAS does not need additional receiving equipment.

What is a virus? In 1983, Fred Cohen coined the term “computer virus”, postulating a virus was "a program that can 'infect' other programs by modifying them to include a possibly evolved copy of itself.” Mr. Cohen expanded his definition a year later in his 1984 paper, “A Computer Virus”, noting that “a virus can spread throughout a computer system or network using the authorizations of every user using it to infect their programs. Every program that gets infected may also act as a virus and thus the infection grows.” Using that explanation, we can see that viruses infect program files. However, viruses can also infect certain types of data files, specifically those types of data files that support executable content, for example, files created in Microsoft Office programs that rely on macros. Compounding the definition difficulty, viruses also exist that demonstrate a similar ability to infect data files that don't typically support executable content - for example, Adobe PDF files, widely used for document sharing, and .JPG image files. However, in both cases, the respective virus has a dependency on an outside executable and thus neither virus can be considered more than a simple ‘proof of concept’. In other cases, the data files themselves may not be infectable, but can allow for the introduction of viral code. Specifically, vulnerabilities in certain products can allow data files to be manipulated in such a way that it will cause the host program to become unstable, after which malicious code can be introduced to the system. These examples are given simply to note that viruses no longer relegate themselves to simply infecting program files, as was the case when Mr. Cohen first defined the term. Thus, to simplify and modernize, it can be safely stated that a virus infects other files, whether program or data. In contrast to viruses, computer worms are malicious programs that copy themselves from system to system, rather than infiltrating legitimate files. For example, a mass-mailing email worm is a worm that sends copies of itself via email. A network worm makes copies of itself throughout a network, an Internet worm sends copies of itself via vulnerable computers on the Internet, and so on. Trojans, another form of malware, are generally agreed upon as doing something other than the user expected, with that “something” defined as malicious. Most often, Trojans are associated with remote access programs that perform illicit operations such as passwordstealing or which allow compromised machines to be used for targeted denial of service attacks. One of the more basic forms of a denial of service (DoS) attack involves flooding a target system with so much data, traffic, or commands that it can no longer perform its core functions. When multiple machines are gathered together to launch such an attack, it is known as a distributed denial of service attack, or DDoS. While purists draw a firm distinction between viruses, worms, and Trojans, others argue that it is merely a matter of semantics and give the virus moniker to all viruses, worms, and Trojans. The term malware, a.k.a. malicious software, can most easily be used to describe viruses, worms and Trojans while satisfying both arguments. Malware is an even more appropriate term when one considers spyware, adware, and and browser hijacking techniques that may not fit in any of the aforementioned virus, worm, or Trojan classifications. Thus, malware can be defined as any program, file, or code that performs malicious actions on the target system without the user’s express consent. This is in contrast to Sneakyware, which can best be described as any program, file, or code that the user agrees to run or install without realizing the full implications of that choice. One of the best examples of Sneakyware was Friendly Greetings, a greeting-card trick that exploited users’ willingness to say Yes without reading

the licensing agreement. By doing so, they were blindly agreeing to allow the same email to be sent to all contacts listed in their address book. To recap: • • • •

Viruses infect other files; Worms make copies of themselves; Trojans perform malicious actions but do not spread; Malware is an all-encompassing term that describes any malicious software program or file operating without the users explicit consent.

Code division multiple access (CDMA) is a form of multiplexing (not a modulation scheme) and a method of multiple access that does not divide up the channel by time (as in time division multiple access), or frequency (as in frequency-division multiple access), but instead encodes data with a special code associated with each channel and uses the constructive interference properties of the special codes to perform the multiplexing. CDMA also refers to digital cellular telephony systems that make use of this multiple access scheme, such as those pioneered by Qualcomm, and W-CDMA by the International Telecommunication Union or ITU.CDMA has since been used in many communications systems, including the Global Positioning System and in the OmniTRACS satellite system for transportation logistics.

The Global System for Mobile Communications, GSM (original acronym: Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. GSM service is used by over 2 billion people across more than 212 countries and territories [1] [2]. The ubiquity of the GSM standard makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs significantly from its predecessors in that both signaling and speech channels are Digital call quality, which means that it is considered a second generation (2G) mobile phone system. This fact has also meant that data communication was built into the system from the 3rd Generation Partnership Project (3GPP).

General Packet Radio Services (GPRS) is a mobile data service available to users of GSM

and IS-136 mobile phones. GPRS data transfer is typically charged per megabyte of transferred data, while data communication via traditional circuit switching is billed per minute of connection time, independently of if the user actually has transferred data or been in an idle state. GPRS can be utilized for services such as WAP access, SMS and MMS, but also for Internet communication services such as email and web access. In the future, it is expected that low cost voice over IP will be made available in cell phones. 2G cellular systems combined with GPRS is often described as "2.5G", that is, a technology between the second (2G) and third (3G) generations of mobile telephony. It provides moderate speed data transfer, by using unused TDMA channels in for example the GSM system. Originally there was some thought to extend GPRS to cover other standards, but instead those networks are being converted to

use the GSM standard, so that is the only kind of network where GPRS is in use. GPRS is integrated into GSM standards releases starting with Release 97 and onwards. First it was standardized by ETSI but now that effort has been handed onto the 3GPP.