Here is a technical comparison of the HD Digital Video Recorders of all DTH providers.

The following list gives you the details of customer contact info for all the DTH service providers in India. All DTH listed as per alphabetical order

AIRTEL DIGITAL TV
TOLL FREE: 1800 102 8080
TOLLED: North: 0124 4448080
East: 033 44448080
West: 020 44448080
South: 080 44448080
WEBSITE: http://www.airtel.in/digitaltv      
FACEBOOK: http://facebook.com/Airtel.In      
TWITTER: https://twitter.com/airtelindia      
EMAIL: digitalTV@airtel.in

Ajai Puri, CEO
Bharti Teletech Pvt. Ltd. Plot no-4,
Sec-20, Phase-1, Udyog Vihar
Gurgaon 122 001
Ph. : 0124 4244294 
Fax : 0124 4244282
M : 9958590000

Airtel Presence
FACEBOOK: http://www.facebook.com/bhartiairtelltd      
TWITTER: https://twitter.com/#!/Airtel_Presence      
EMAIL: airtelpresence@in.airtel.com
DIRECT CONTACT: http://www.airtel.in/airtelpresence      
NOTE: They Solve all airtel related issues(DTH,Landline/Broadband,Mobile)
DD DIRECT PLUS
WEBSITE: http://www.ddinews.gov.in/DTH/DDDIRECT        

M.C.Aggarwal
Room no-531 A, Doordarshan Bhawan,
Copernicus Marg, New Delhi-110001
Mob: 9818394454 Tel: 011-23383396  

DISH TV
TOLL FREE: 1860-180-3474 (Only BSNL/MTNL lines)
TOLLED: 0120-2550000 (All phone lines),
Northern India: 011 -60013474
Southern India: 044 -60013474
Eastern India: 033 -60013474
Western India: 022 -60013474
Dish TV for vehicles: 09711443366
WEBSITE: http://www.dishtv.in      
FACEBOOK: http://www.facebook.com/dishtvindia      
TWITTER: https://twitter.com/Dishtv_India      
EMAIL: customercare@dishtv.in
SMS: DISHTV to 57575

Salil Kapoor, CEO
FC-19 Sec-16A Filmcity,
Noida-201301 Tel: 95120-2599391/ 2599555
salil_kapoor@dishtv.in

RELIANCE DIGITAL TV
TOLL FREE: All India (except North East states and J&K) :
1860 200 6666
1800 200 9001
TOLLED: Assam: 9864098888
Other North East States: 9863098888
Jammu & Kashmir: 0191-2475018
WEBSITE: http://www.reliancedigitaltv.com      
FACEBOOK: http://www.facebook.com/RelianceDigitalTV      
TWITTER: https://twitter.com/reliancedtv      
EMAIL: customercare@reliancedigitaltv.com

Sanjay Behl, CEO
A 202, 6 Auranzeb Road New Delhi-110011
Tel: 011-30321100/30321122
Fax: 011-30321101
Email:sanjay.behl@relianceada.com

SUN DIRECT
WEBSITE: http://www.sundirect.in      
CUSTOMER CARE: http://www.sundirect.in/customer-care.php      

Tony D’Silva, CEO
93, Kodambakkam High Road,
Chennai-34
Tel: 040-8204236/8242237
tony@sundirect.in

TATASKY
TOLL FREE: 1860 425 6633 (MTNL/BSNL lines)
TOLLED: Western India: 020 6600 6633
Northern India: 0172 6600 6633
North East: 0361 6000 6633
Southern & Eastern India: 040 6600 6633
WEBSITE: http://www.tatasky.com/      
EMAIL: help@tatasky.com
SMS: BUY to 56633

Harit Nagpal CEO
3rd floor Bombay dying AO Building,
Pandurang Pudhkar Marg, Worli,
Mumbai-400025
Tel: 022-66133000

VIDEOCON D2H
TOLLED: 09082099999
WEBSITE: http://www.videocond2h.com      
FACEBOOK: http://www.facebook.com/videocond2h      
TWITTER: https://twitter.com/videocon_d2h      
EMAIL: customercare@d2h.com

Anil Khera, CEO
Bharat Business Channel Limited
5th Floor, A wing, Corporate Centre,
Opp Hotel Vits, Andheri Kurla Road,
Andheri (East), Mumbai-400 059

In order to receive good signal quality from the Satellites aligning the Dish Antenna in the right direction is very important.
But not many know that we could actually calculate the direction at which the Dish has to be mounted using a trigonometric formula. These values are called as the Azimuth angle and the Elevation angle. Now lets see what these angle mean.

Azimuth Angle:
Azimuth refers to the rotation of the whole antenna around a vertical axis. It is the side to side angle. Azimuth is the turning of your satellite dish East and West or Left & Right.  This is the same as your compass reading.  Make sure when you look on your compass for the proper degree, that your compass is away from your satellite dish, because metal can affect the reading on your compass. Typically you loosen the main mount bracket and swing the whole dish all the way around in a 360° degree circle.

Elevation Angle:
Elevation refers to the angle between the dish pointing direction, directly towards the satellite, and the local horizontal plane. It is the up-down angle. Elevation is how high up the signal is coming from. You can usually measure your elevation based on the degree markings on the back bracket of your satellite dish antenna. Make sure you don't tighten the bolts too much to leave room for play in case you need to fine tune your antenna with your signal meter. Once you fine tune to the highest possible signal, you can tighten the elevation bolts.  When your dish is pointed at low elevation angles, below 5 deg at C band and 10 deg at Ku band, the path through the atmosphere is longer and the signals are degraded by rain attenuation and rain thermal noise. Scintillation also occurs, particularly in hot humid weather. This causes increases and decreases in the signal level frequently.

Now the formula:
Elevation = ATAN((COS(ACOS(L * COS(S-N))) - 0.1512) / SIN(ACOS(COS(L) * COS(S-N))))
Azimuth = ACOS(-TAN(L)/(TAN(ACOS(COS(L)*COS(S-N)))))
where,
L is the Latitude of your city in North
N is the Longitude of your city in  East
S is the Satellite's Longitude in East

For those who are not familiar with Trigonometry, go to the Tools Page to find a java script calculator to calculate the angles easily.