Link Budget

i want 2 know whether we use half bit rate of QPSK modulated carrier in the calculation of satellite link budget or full bitrate........

use ADS ptolemy

Ptolemy You can use for modelling but I feel you should refer the books on satellite communication where they have mentioned the link budget calculation or find the link below for link budget calculation:
http://www.accessmylibrary.com/coms2...6-31853873_ITM
Hope this will be helpful for your calculation purposes.