Comtech EF Data CDM-625A - Page 624

CDM-625A Advanced Satellite Modem MN-CDM625A
Appendix F Revision 4
F–18
F.3.2 Methods to Estimate PSD Ration
F.3.2.1 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
F.3.2.2 Use LST