What is DTH ?

Hello everyone, how are you all?? I hope you all enjoy reading my blogs so I thought of this new topic to help u broaden your knowledge as well as to have fun in your leisure time. But I didn’t see any comments from you. I know you people read my blogs but if you don’t comment then how will I know whats your interest and what am I lacking in?? So whatever you think, excellent, good, satisfactory, poor or anything else, please comment it. It can help me improve the way I write my blogs in future.

DTH, a blooming trend in the present world of infotainment is actually an acronym of Direct To Home. Nowadays its most highly appreciated technology in all around the globe for high quality video transmission. As we have generally seen, it not only can transmit TV and radio, but it is also used for data transfer in several parts of the world. Since it makes use of wireless technology, TV channels are sent to the subscriber's television direct from the satellite eliminating the need for cables and any cable infrastructure. Then how does a DTH works then?? How can we get such high quality pictures via DTH than normal cable distributed TV channels??

Now let me quench the thirst of your curious mind one by one. First lets start with what is DTH ? DTH is generally a satellite television broadcast system. It is a kind of DBS-TV(Direct Broadcast Satellite Television). The TV signal you receive is directly received from the satellite. No intermediate connection is necessary. These TV broadcast are served by geostationary satellite (which is located at 36,785 km above earth surface). Looking at the history it is found that, first direct broadcast of video via satellite was done in the Tokyo Olympic games in 1968. Since then this technology is extensively used commercially in the field of satellite communications. This technology is the greatest source of revenue generation for satellite companies till date.

Although the digital video transmission was used since 1960s, it was not commercially applied. The receiver antenna was large  and the decoding of the signal was also a tedious task. But in 1990s, digital video transmission became feasible. The development of low cost and small sized antennas and receivers, high speed digital integrated circuits, error control mechanisms, encryption and decryption of MPEG format video made the DBS-TV practically realizable. This gave rise to the fully digital DBS-TV which is also known as Direct TV. This Direct TV is commonly called DTH.

Then Hughes Electronics Corporation started commercial use of Direct TV by launching its first satellite for DBS-TV in 1993. The satellite was called DBS-1. After the launch of DBS-1 the company started providing limited service to the civilians. In 1993 and 1994, DBS-2 and DBS-3 was launched. Since then several satellites are launched for DBS-TV transmission. Direct TV was the first brand in the field of DTH and it alone has more than 80 million customers till date. Other giant vendors for DTH transmission are STAR TV, Telestar, Echostar, DISH TV, Astro etc. For more details of DTH vendors click here. These companies provide use of their satellite for the transmission in other small countries.

We all know we have mainly two parts in a general DTH system. An outdoor part i.e. Antenna and another is indoor part i.e Signal decoder also known as “Set top box”. The antenna acts as the signal receiver. In antenna there is a combination of two types of antenna, one is parabolic reflector antenna (the curved shaped metallic plate) and another is feed (generally HORN antenna is used). Feed is kept in front of the parabolic reflector antenna facing towards it. It is the feed, which is directly supplied by the  signal. The parabolic reflector is used just for directivity of signal. In DTH telecast the signals are transmitted in Ku band(10.7 GHz to 18 Ghz) and are received by the subscribers through a small dish antenna (nearly 60 cm diameter) and a set top box. The simplified block diagram of DTH receiving system is shown below.

There is a block in the receiver which verifies the user identity/ account and checks for his balance then only will decode the received signal. In this way the cost control is done.

In addition to TV and radio transmission, some of the companies also provide data facilities. These data are also encoded as encoding of other video and audio signal and is transmitted. The receiving side extracts data from the received signal.

                        Figure: Detailed diagram of DTH transmission

Advantages:

·         Easy installation

·         User friendly

·         Portable and efficient for home user

·         High definition video transmission

·         Reliable

·         Economical

Disadvantages:

·         time delay (normally it has time delay of about 2 seconds, as it is the time required for signal to reach satellite and come back to earth again)

·         disturbed by bad weather.

·         Only one user can be served by one receiver

This was all I could help you understand. Its just introductory article so for more technical details you may contact me or use the references. Thanks for reading.

References:

·         Pratt,T., Bostian,C.W., Allnutt,J.E. “Satellite Communications”.2nd Edition.John Wiley and Sons.

·         http://en.wikipedia.org/wiki/Direct_To_Home

·         http://www.dishhome.com.np/what-is-dth

Engineering Projects Ideas for New Nepal.....

Engineering, in one word its heart of everything we have today. From a tiny toy to huge skyscrapers, engineering is the core of everything. Generally Engineering is the stream that helps to make people's lifestyle easier nowadays. And according to my personal aspect, Engineering is something that must modify and make lifestyle easier and must no violate humanity and environment features.

During studies of Engineering (especially BE), students must complete a project in order to gain some practical experience in working with the related materials and a team. May be I'm not capable of writing this blog from many aspects, I'm just trying to list out some of the useful techniques and ideas I learnt so that our  juniors will not face the problem I faced. I've compiled a list of all kinds of electronics projects that may be relevant in context of Nepal. I believe in the concept "Don't reinvent the wheel", so I've tried to make a list that may be quiet unique for you guys. And let me tell you clearly that, most of the project ideas are inspired from several incidents, peoples, systems and various sites. I have written this blog in order to facilitate students who are in confusion of choosing a project. As it is said "A journey of miles begins with a single step", I've just taken a little step to make youth innovative. I hope you people will join me and make it large. 

One of my senior said me that "Nepal is the country of problems but that is an opportunity for people like us to do something innovative to develop it." Of course, he was correct. Engineers are called creatures of logic, so being a creature of logic, we must try to find solutions of a certain problems. 

Reinventing the wheel by copying some international developed countries standard, our hard work, talent is total waste. So if we do some activities that can help our community to grow up, our effort will definitely count up someday.

Now without any further delay, i'll take you to our topic. 

According to Nepalese University system, most of the university has requirement of one minor project and one major project. 

Minor project must minimally be able to solve few problems or must be able to do at least one or two tasks. The tasks and problem may be of your choice.

In the other hand, major project must be accomplished by making a complete system comprising of several subsystems. you can use any micro-controller for your project.

And most importantly, both the project must be done in a team. A single student project is not allowed.

Now first of all lets list out the problems in Nepal. And then list out the solutions for it.

Problems in Nepal:

1. Energy Scarcity
2. Health problems
3. Lack of education
4. Traffic
5. Poverty
6. Traditional working pattern
7. Lack of support for disabled people
8. Water supply
9. Slow government works
10. Internet bandwidth
11. Lack of public awareness
12. Lack of digitization
13. and many others......

Just finding out problems and not doing anything is a shame for all technical students. So even all of us just include one of any smallest problem from our society and solve it, that can be a great contribution for development of our country.

Solutions by using Engineering ( Minor Project List):

1. E-portals for government institutions.
2. Automatic Traffic light control based on vehicle pressure
3. Paper free Offices (Centralized Server)
4. Green Industries (industrial waste status indicator)
5. E-Hospital/Online hospital
6. Automated Museum
7. Interactive Displays
8. Pinless Recharge 
9. Water Level Alarm in rivers to detect flooding
10. Automated Irrigation projects
11. Greenhouse projects
12. Patients status monitoring software
13. Online education
14. Solar tracking
15. Power load indicator
16. Digital hoarding boards
17. Wind Mill (Electricity generation by wind)  
18. Mobile shield
19. Intelligent automatic three phase shifter system
20. Ultrasonic mosquito repellant 
21. Automatic staircase lamps
22. Shadow alarms
23. Versatile power supply
24. Vibration Detector
25. Shadow detector with alarm
26. Friendly mobile chargers
27. Automatic timer for DVD players
28. Digital Energy meter 
29. Mobile shield
30. Earthquake sensor
31. Voice controlled circuits
32. Sun-Down switch( Advanced Street light controller)        
33. Visitor counter
34. Pollution controlling Tower ( It filters the solid particles from smoke)
35. Effect of current through a magnetic coil
36. Generation of electricity by moving magnetic field
37. Digital thermometer
38. Digital Hoarding Displays
39. Brake Failure Detector
40. Fuel Reserve Indicator
41. Friendly Energy consumption indicator

More projects and major project lists will be published very soon. And I'd like to humbly resuest all the seniors and experts to contribute project names in comment below. your list will be put on the blog. I hope to get positive response and help from everyone. Thank You!! Lets help Nepalese youth be more innovative and better than students from any country in the world.