Comtech EF Data CDM-625 - Manual (Page 348)

CDM-625 Advanced Satellite Modem Revision 15
DoubleTalk Carrier-in-Carrier Option MN-CDM625
10–18
10.5.2 Methods to Use to Estimate PSD Ratio
10.5.2.1 Use Downlink EIRP and Symbol Rate
Use Downlink EIRP and Symbol Rate to estimate the PSD Ratio from a link budget:
PSD = Downlink EIRP – 10 * Log (Symbol Rate)
PSD Ratio Example:
Carrier Downlink EIRP Symbol Rate Power Spectral Density
A to B 27 dBW 500 ksps -29.99 dBW/Hz
B to A 24 dBW 375 ksps -31.74 dBW/Hz
PSD Ratio (@ A) = -29.99 – (-31.74) = 1.75 dB
PSD Ratio (@ B) = -31.74 – (-29.99) = -1.75 dB
10.5.2.2 Use LST