Hi, I checked the max. input rate of different receivers. some of them can reach 80Mbit/s, some of them are only 15Mbit/s. is it important to have the receiver with high input bit? what 's the max input rate for TV normally? thanks.
Normally the 15Mbit/sec would be allocated to the minimum spec on a comercial receiver (or one used for older style reception on a dedicated transmission for subscriber card only)
For this type of hobby the best ones to go for are 1 - 35 (or even 45) Mbit/s
(though a while ago there were receivers in the Echostar and Manhattan brand name that claimed these figures, but could not reach 32Mbit/sec.
Are you sure you have got the right specification?
Bits/sec refers to i.f. passband of the receiver. Max bitrate is (approx) twice frequency passband. Too narrow passband filtering of the i.f. will distort the signal and increase demodulation error rate.
Symbol rate depends on modulation system used, which - at least currently - is QPSK for satellite (2 symbol bits per phaseshift).