Q 2.25-1 Jacek Pawlowski , How many SD/HD channels can we get from one transponder?

Number of channels supported by a satellite transponder depends on numerous variables:

TV transmission standard – standard definition (SD) or high definition (HD);

Satellite transmission standard: DVB-S or DVB-S2;

Video compression standard: MPEG-2 or MPEG-4;

Permissible modulation and coding schemes: QPSK, 8PSK, etc. as defined in the chosen standard. 

Traditional SD quality transmissions tend to use MPEG-2/DVB-S combination; more recent introductions particularly in support of HD use MPEG-4/DVB-S2.

Consider an example.

Video bit rates of 4 Mb/s for MPEG-2/SD and 10 Mb/s for MPEG-4/HD;

Transmission symbol rate = 26 Ms/s (that fills a 36 MHZ transponder);

Coding rates = respectively ½ and 7/8;

The corresponding numbers of SD TV channels in a 36 MHz transponder are estimated as 6 and 11 respectively, reducing respectively to 2 and 4 HD channels (Ref 2.25).

Since bandwidth = Symbol rate*(1+roll off factor),

With a typical roll-off of 0.35, corresponding bandwidth at 26 Ms/s = 35.1 MHz, adequate to fill a 36 MHz transponder.


Available: http://www.tele-audiovision.com/TELE-satellite-1107/eng/sdinhd.pdf, retrieved 3/3/2018.