WgpShashank
Monday, January 16, 2012
Why Programmer Works @ Night ..A Programmer Must Read :)
Friday, March 11, 2011
SATELLITE COMMUNICATION
A communications satellite (sometimes abbreviated to SATCOM) is an artificial satellite stationed in space for the purposes of telecommunication.
In telecommunication, the use of artificial satellites to provide communications links between various points on Earth. Communications satellites relay voice, video, and data signals between widely separated fixed locations (e.g., between the switching offices of two different national telephone networks), between a fixed location and numerous small fixed or mobile receivers in a designated area (e.g., direct satellite broadcasting of television programming), and between individual mobile users (e.g., aircraft, ships, motor vehicles, and personal handheld units). The technique involves transmitting signals from an Earth station to a satellite. Equipment onboard the satellite receives the signals, amplifies them, and retransmits them to a region of Earth. Receiving stations within this region pick up the signals, thus completing the link.
Satellites provide communications links via microwave radio, most commonly in the superhigh-frequency band of 3 to 30 gigahertz (3 billion to 30 billion hertz, or cycles per second). These frequencies correspond to wavelengths ranging from 10 cm to 1 cm (4 inches to 0.4 inch). On land this can be achieved by using towers or hilltop locations, but microwave communication across oceans is impossible without the use of satellites.
FREQUENCY BANDS
The specific frequency bands open to civilian satellite communication are assigned by the International Telecommunication Union, based in Geneva. Each band consists of an uplink (Earth-to-satellite) frequency and a downlink (satellite-to-Earth) frequency .The two bands that have been in use longest, and still carry the most traffic, are the C band, with uplink frequencies centred on 6 gigahertz and downlink frequencies centred on 4 gigahertz, and the Ku band, with uplink/downlink frequencies centred on 14/11 gigahertz.
TYPES
There are three different types of satellite systems.
1. International satellite communication system INTELSAT.
2. Domestic satellite system DOMSAT.
3. Search and rescue system SARSAT.
INTELSAT
The INTELSAT Organization was established in 1964 to handle the myriad of technical and administrative problems associated with a world wide telecommunication system. The international regions served by INTELSAT are divided in to the Atlantic Ocean region (AOR), the Pacific Ocean Region (POR) and the Indian Ocean region (IOR). For each region , satellites are positioned in geo-stationary orbit above the particular Ocean, where they provide a transoceanic telecommunication route. In addition to providing trans oceanic routes, the INTELSAT satellites are used for domestic services within any given country and regional services between countries. Two such services are vista for telephony and Intelnet for data exchange.
DOMSAT
Domestic satellites are used to provide various telecommunication services, such as voice, data, and video transmission (T.V channels), with in a country.
SARSAT
SARSAT is one type of Polar orbiting satellites.
Polar-orbiting satellites orbit the earth in such a way as to cover the north and south polar-regions. Infinite number of polar polar satellite orbits are possible
Polar satellites are used to provide environmental data , and to help locate ships and aircrafts in distress .This service known as SARSAT, for search and rescue satellite.
ADVANTAGES
o HIGH CAPACITY
o LONG RANGE
o GOOD QUALITY
o COVERAGE
o REALIABLITY
APPLICATIONS
AIR TRAFFIC CONTROL(ATC)
Satellites can provide two types of communication services to support air traffic control functions. Air traffic control satellites collect navigation data from ground monitoring systems and broadcasts it to aircraft aloft, greatly increasing the navigational accuracy and reliability of the global positioning system (GPS) for aircraft location and safe take-offs and landings. These satellites also provide a highly reliable digital communications path for air traffic controllers and pilots to share vital flight information.
BROAD BAND DIGITAL COMMUNICATIONS
Broadband satellites transmit high-speed data and video directly to consumers and businesses. Markets for broadband services also include interactive TV, wholesale telecommunications, telephony, and point-of-sale communications, such as credit card transactions and inventory control.
DIRECT BROADCAST SATELLITES
Direct-broadcast satellites (DBS) transmit signals for direct reception by the general public, such as satellite television and radio. Satellite signals are sent directly to users through their own receiving antennas or satellite dishes, in contrast to satellite/cable systems in which signals are received by a ground station, and re-broadcast to users by cable.
ENVIRONMENTAL MONITORING
Environmental monitoring satellites carry highly sensitive imagers and sounders to monitor the Earth's environment, including the vertical thermal structure of the atmosphere; the movement and formation of clouds; ocean temperatures; snow levels; glacial movement; and volcanic activity. Large-scale computers use this data to model the entire earth's atmosphere and create weather forecasts such as those provided by national weather services in the U.S. and abroad
FIXED SATELLITES SERVICES
Satellites providing Fixed-Satellite Services (FSS) transmit radio communications between ground Earth stations at fixed locations. Satellite-transmitted information is carried in the form of radio-frequency signals. Any number of satellites may be used to link these stations. Earth stations that are part of fixed-satellite services networks also use satellite news gathering vehicles to broadcast from media events, such as sporting events or news conferences. In addition, FSS satellites provide a wide variety of services including paging networks and point-of-sale support, such as credit card transactions and inventory control.
MILTARY APPLICATIONS
RADAR(Radio Detection And Ranging) is used to detect the targets such as submarines and air craft along with its distance.
CONCLUSION
Thus satellite communication provides the basis of the different types of communication in today’s world.
Wi-Fi
WIRELESS FIDELITY
INTRODUCTION:
Wi: Wirless Fi: Fidelity.
The name itself indicates that wireless data carrying capacity so it is called wireless Fidelity. WiFi is the way to connect devices together without wires.
HOW DOES IT WORK:
Wireless Internet Access has four components that form its structure. The four components are,
1)High-speed access which is also known as broadband is an internet connection which is generally faster than dial up service. Example: satellite service.
2) Network Gateway is between your high-speed access connection and the wireless network, it acts like a gate. This gate will prevent people from accessing your wireless network unless you know about it, the gateway also allows managing tools as well.
3) Wireless network is a system of connecting PC's and otherdevices within the same physical proximity using high frequency radiowaves instead of wires.
4) Wireless customers are people who have a PC and a wireless adapter . The wireless adapter can be built in or it can be an external device plugged into your computer.
The radio waves are transmitted from antennas and routers and are picked up by WiFi receivers s. When these devices receive a signal, the WiFi card then reads the signals and produces an internet connection.
HOT SPOTS:
Hot spots are connection points for WiFi networks; areas where wireless internet is available for those who have internet ready devices. Hot spots are becoming available everywhere, in airports, hotels, etc.
HOW SECURE IS WiFi:
wireless LANs are more vulnerable due to the fact that the data travels over radio waves which are much easier to intercept. In 2002 the wireless LANs security was upgraded when WiFi Protected Access (WPA) was introduced. WPA had several improvements like better encryption, and it also used the RADIUS-based 802.1X, which authorizes the user to gain access to the ISP provider.
In 2004 802.11i was completed and became the new and current standard for WiFi. 802.11i is also nown as WPA2. WPA2 upgraded its encryption of data with the Advanced Encryption Standard
Many corporations today use a Virtual Private Network (VPN) to send and receive important information by creating a tunnel connecting the two end users. VPN encrypts the data to keep any hackers from stealing the information while it is being sent
FUTURE WiFi ADVANCEMENTS:
BLUETOOTH:
It is a wireless technology that allows computers, phones and other devices to talk to each other over short distances. In non-discoverable mode of devices all your information and data are safe. However, in order to receive business contacts wirelessly you will need to place the phone in discoverable mode.
ULTRA WIDEBAND MODULATIONS(UWB): one of the most leading technologies is Ultra-wideband (UWB) modulations. UWB usually refers to a radio modulation technique based on transmitting very-short-duration pulses . UWB operates at such low power, it has very little interference impact on other systems.
RADIO FREQUENCY IDENTIFICATION TAG (RFID):
It is a small silicon microchip attached to an antenna that emits a unique serial number via radio over short distances. And, just as a bar code or magnetic strip must be scanned to get the information, the RFID device must be scanned to retrieve the information. . RFID tags can also be placed in living organisms to help track or identify them within short distances. RFID tags can be read without your knowledge which enables others to view information about you.
ADVANTAGES:
Reduces the costs of network deployment and expansion.
The price of chipsets for Wi-Fi continues to drop.
Unlike mobile telephones, any standard Wi-Fi device will work anywhere in the world.
The current version WPA2 is not easily defeated, provided strong passwords are used.
LIMITATIONS:
Wi-Fi signal actually occupies five channels in the 2.4 GHz band resulting in only three non-overlapped channels in the U.S.and three or four in Europe.
Security problems.
WAYS TO PROTECT YOUR WIRELESS COMPUTER:
You should have strong passwords on your wireless.
Another way to protect yourself is to download firewalls onto your computer.
Downloading anti-virus software onto your computer is another way to protect your computer. You should update your anti-virus software often .
Also when you are not on your computer, you should turn it off.
CONCLUSION:
WIFI has a lot of advantages over its disadvantages, hence we must understand that we have to take the proper precautions to make the WIFI technology more secure .
Sunday, January 9, 2011
Bsnl Broadband Connection setup in Ubuntu
**Method I:
Connecting broadband through command-line-Bridge Mode
/* all ubuntu versions*/
Note: your modem must be set in bridge mode
Steps:
1. Open a terminal
2. Type sudo pppoeconf
3. Enter sudo password if prompted
4. A window with blue screen pops up notifying the devices that are found
5. Follow the on screen instructions and press yes till you reach the screen which asks you to enter username
6. Backspace to delete the text username and then enter the username your ISP has provided you with
7. Press yes again and then enter the password
8. Follow the instructions till it asks you "Do you want to start the connection at start up."
Give yes if you want.
9. After setup is complete you will be prompted with a message in the terminal
10. To start the connection type pon dsl-provider in the terminal
Now, your internet connection gets activated.
11. To terminate this connection type poff in terminal
**Method II:
Ubuntu 8.10(hardy) and 9.04(jaunty) users often face a problem
Problem:The network menu does not appear in System>Administration
The solutions are:
*Method I:
1. Goto Applications>Add/Remove
2. In Show, from the drop-down menu select All available applications
3. In Search tab: type network
4. In Application: check the box next to Network(configure network devices and connections)
5. Apply changes
/*To download this file you need active internet connection*/
*Method II:
1. Open a terminal
2. Type network-admin
3. If your Network Settings is not installed then it will ask you to type
sudo apt-get install network-admin
4. If there is an active internet connection the Network Settings will be installed and it can be located under System>Administration>Network
Now,coming to configuration of Bsnl broadband connection through Network Settings
Steps:
1. Switch off your modem
2. Open Network Settings dialog box form System>Administration>Network
3. Select Wired Connection and click on Properties
4. In the Connection Settings Menu select Static IP and type in the following values and save:
IP Address : 192.168.1.2
/*Assigning the Ethernet Card an IP different from that of the modem*/
Subnet Mask: 255.255.255.0
Gateway address: 192.168.1.1
/* The Modem is being made the default gateway*/
5. Switch on the Modem .
6. Open the Terminal and type sudo pppoeconf
7 .A window with blue screen appears notifying the devices found
8. Press yes till the screen appears that asks you to enter username
9. Backspace to delete the text username and then enter the username your ISP has provided you with
10. Press yes again and then enter the password
Now, your internet connection gets activated.
Note: To check the IP configuration open a terminal and type ifconfig ppp0
The IPV4 address, default gateway and subnet mask addresses are shown
Tuesday, January 4, 2011
The Social Network (2010) - FaceMash Algorithm (
I saw Social Network three times in 1 week. Not for entertainment. Not because I had nothing better to do. But because I wanted to understand the math and computer science fundae used in the movie. I would like to discuss one particularly interesting scene from the movie.
You may remember Mark inviting his friend Eduardo to give him his chess algorithm at the beginning of the movie (Mark was drinking, blogging and hacking simultaneously and creating Facemash.com). You may also remember the scribbles on the window:
and
What is this? This is actually the math behind Elo Rating System. Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess. It is named after its creator Arpad Elo, a Hungarian-born American physics professor.
As explained in the movie, Facemash was quite simple. Not unlike hotornot.com, students went to a page and 2 random images of girls were picked and presented to them. The students then had to click on the hottest girl presented to them and then another set of two girls would be presented asking the students to repeat the same actions they had done. The difference with hotornot was that the girls presented were all Harvard students. In other words, the students were rating girls of Harvard based on their looks (You can imagine why Mark got into trouble).
The algorithm used - The Elo Rating system - insured a fair rating and ranking of the girls. A hot girl A winning over hot girl B girl would gain more points than winning (or being picked) against ugly girl C. Same goes for the following: ugly girl C wins over ugly girl D. ugly girl C gains some points in her general ranking. If ugly girl C wins over hot girl A then ugly girl C gains more points because the ranking of hot girl A is much higher than ugly girl D. The previous scenario is roughly what the algorithm implemented by Mark was doing. It was somewhat insuring a level of fairness despite the misogynistic nature of the product.
In today’s society, the Elo Rating system is used by many rating and ranking system to predict the outcome of matches but also insure a level of fairness between teams of different levels playing against each others. FIFA uses it to rank football teams.
You can read more about the system on wikipedia page(http://en.wikipedia.org/wiki/Elo_rating_system).
The Social Network (2010) - FaceMash Algorithm
The Social Network (2010) - FaceMash Algorithm
I saw Social Network three times in 1 week. Not for entertainment. Not because I had nothing better to do. But because I wanted to understand the math and computer science fundae used in the movie. I would like to discuss one particularly interesting scene from the movie.
You may remember Mark inviting his friend Eduardo to give him his chess algorithm at the beginning of the movie (Mark was drinking, blogging and hacking simultaneously and creating Facemash.com). You may also remember the scribbles on the window:
and
What is this? This is actually the math behind Elo Rating System. Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess. It is named after its creator Arpad Elo, a Hungarian-born American physics professor.
As explained in the movie, Facemash was quite simple. Not unlike hotornot.com, students went to a page and 2 random images of girls were picked and presented to them. The students then had to click on the hottest girl presented to them and then another set of two girls would be presented asking the students to repeat the same actions they had done. The difference with hotornot was that the girls presented were all Harvard students. In other words, the students were rating girls of Harvard based on their looks (You can imagine why Mark got into trouble).
The algorithm used - The Elo Rating system - insured a fair rating and ranking of the girls. A hot girl A winning over hot girl B girl would gain more points than winning (or being picked) against ugly girl C. Same goes for the following: ugly girl C wins over ugly girl D. ugly girl C gains some points in her general ranking. If ugly girl C wins over hot girl A then ugly girl C gains more points because the ranking of hot girl A is much higher than ugly girl D. The previous scenario is roughly what the algorithm implemented by Mark was doing. It was somewhat insuring a level of fairness despite the misogynistic nature of the product.
In today’s society, the Elo Rating system is used by many rating and ranking system to predict the outcome of matches but also insure a level of fairness between teams of different levels playing against each others. FIFA uses it to rank football teams.
You can read more about the system on wikipedia page(http://en.wikipedia.org/wiki/Elo_rating_system).
Saturday, December 4, 2010
Google Acquires Phonetic Arts To Make Robo-Voices Sound Human
No, Google hasn’t acquired Groupon (yet). But it does have a smaller, though very interesting acquisition to announce: it’s just acquired Phonetic Arts, a company based in the UK that works on speech synthesis in games.
Phonetic Arts makes technology that can convert lines of recorded dialog into a ‘speech library’ — feed it a few hundred lines of recordings using your voice, and it can then piece together those sounds to generate new sentences that sound surprisingly realistic. Up until now Phonetic Arts has primarily been focused on using this technology for games, but Google intends to use it more broadly to make its own automated voices sound more fluid and human.
In case you haven’t noticed, Google has been paying a huge amount of attention to its voice recognition and transcription technologies over the last few years (they’ve been researching it much longer, but now the tech is making it into products). YouTube now includes automatic voice transcription captions for millions of videos; Android has voice recognition integrated throughout the OS; and Google has voice search apps for other mobile platforms, like the iPhone.
But while these voice recognition apps are getting much better, whenever they need to read something back to you (for example, for language translation or GPS navigation) it’s quite obvious that you’re listening to a computer. Which is where Google is planning to start applying Phonetic Arts’ technology.
Also worth pointing out: in its official blog post, Google specifically talks about the growing tech scene in London:
There’s a particular focus right now in the U.K. on technology and innovation, and we’re delighted to be deepening our investment in the country with this acquisition. We already have a strong engineering center in London and look forward to welcoming Phonetic Arts to the team. We are excited about their technology, and while we don’t have plans to share yet, we’re confident that together we’ll move a little faster towards that Star Trek future.