DTH Basics Business Development Service 1 T O
DTH Basics Business Development (Service) 1
T O C (Table of Content) Content What is DTH How DTH works Type of DTH Connections Advantages of DTH Components of DTH Sun Direct Parameters Elevation & Azimuth Skew BER – Bit Error Rate MER – Modulation Error Ratio Rain Fade Solar Fade Health & Safety
q DTH stands for Direct To Home q DTH is the direct mode of transmission between ‘Broadcaster’ and ‘Subscriber’ through satellite. Satellit e Broadcast er Subscrib er
Advantages of DTH q High quality Picture & Sound q Un-interrupted Viewing q Reaches Remote Areas q Pay only for your choice Channels q Interactive Features (like, Video on Demand)
Foot Prints The Geographic area covered by satellite is called as its Footprint Contour of the footprint matches that of the geographical boundaries of the area intended to be covered.
How does DTH work ?
Type of DTH Connections SDU – Single Dwelling Unit q Maximum 4 STBs can be connected from Single Dish MDU – Multi Dwelling Unit q More than 4 STB can be connected from Single Dish q Used to provide DTH Solution for High Rise / Multi Story Building. 0 Multi Switch 0 0 0 Multi Switch
Components of DTH Function : Reflector receive the Signal & focus to the LNBF. Installation Precautions : - q There should not be any scratch on the reflector surface q Reflector / LNBF Arm should not deform or bend. Reflector Function : Down converts RF signals to IF signals ( From High Frequency LNBF to Low Frequency ). Types : Universal / Single - Used for SDU Connection ( Single STB ) Dual - Used for SDU Connection ( Maximum Two STB ) Quad - Used for SDU Connection ( Maximum Four STB ) Quattro - Used for MDU Connection ( More than Four STB ) Installation Precautions : - q LNBF should be installed at Focal Point of Reflector q Proper Skew Alignment should be done as per Look angle Chart.
Components of DTH Function : Connector connects cable with Equipment. Type : RG - 6 (F type Compression) RG - 11 (F type Compression) Installation Precautions : Connector q Take extreme care while Connectorisation to avoid repeated complaints Function : Carries Signals from one end to other end. Types : RG - 6 (Coaxial Cable- 3 Ghz) RG – 11 (Coaxial Cable- 3 Ghz) Installation Precautions : - q Take extreme care during Cabling to avoid cable damage. q Take extreme care while taking out cable from cable drum
Components of DTH Function : - q STB decodes the signals q Provides supply to LNBF q Converts Digital signals into Analog signals Set Top Box Installation Precautions : - Ø TV & STB should be switched OFF while connecting cables Function : - Smartcard works as an access card for channel viewing. Installation Precautions : - Smart Card q Insert Smart card with care.
SUN DTH Parameters Our Satellite : INSAT 4 B (93. 50 E) Satellite Position : 93. 50 East S. No. Transponder Frequency Polarisation FEC Symbol Rate ( MHz ) 1 11030 Vertical 3/4 27500 2 11110 Vertical 3/4 27500 3 11185 Vertical 3/4 20000 4 11530 Vertical 3/4 27500 5 11610 Vertical 3/4 27500 6 11645 Vertical 3/4 20000
Elevation & Azimuth Elevation Azimuth The vertical movement of Reflector to track The horizontal movement of Reflector to track the satellite is called Elevation Adjustment. the satellite is called Azimuth Adjustment.
Skew q LNBF contains two antenna (Vertical & Horizontal) with 90 degree phase shift. q Skew is the amount of rotation of LNBF to match LNBF antenna with polarized signal direction. q To get maximum signal we have to match Antenna angle with received signal angle. Horizontal Antenna Vertical Antenna Horizontally Polarized Signal LNBF If SKEW is not done properly, few channels may not be seen.
Skew Marking on LNBF & LNBF top clamp are for Skew adjustment. 5 Degree 9 divisions For example: - If Polarization is -23 degree for a city, so set at 4. 6(approx) division of the LNBF (Left side division) with the centre point of the LNBF Clamp. Look Angle Chart
BER – Bit Error Rate BER is the ratio between total bits transmitted and the number of bit not interpreted by the de-modulator. INSAT 4 B Satellite No of Bit not interpreted by Demodulator (e. g. 3 bit error) Total bits transmitted (e. g. 10000 bit ) For Example Customer House 3 E-4 = 3 x 10 -4 = 3/10000 = 3 bit error in 10, 000 bit 2 E-4 means 2/10000 = 2 bit error in 10, 000 bit 6 E-5 means 6/100000 = 6 bit error in 1, 000 bit A good quality of Signal has BER of 1 E-4 or 1 E-5.
Rain Fade During Raining or snow fall, Rain, Snow or Rain filled clouds can reduce intensity of Ku band signals coming from satellite to the subscriber. Under Clear Sky condition For example MER = 13 d. B How to Counter-act q Tracking should be done up to peak level. During Rain fall For example MER = 7 d. B Picture freezing / No Picture
Solar Fade Exact time depends upon the position of the Satellite. What happens The sun passes through this plane. As seen from the ground, the sun seems to pass behind the satellites once a day. During the time when both the satellite and the sun are in the ground station's field of view, the energy from the sun can overpower the signal from the satellite, as shown in the below diagram
- Slides: 17