[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

more P3D questions: orbit / xponder gain

I have a couple more questions about numbers for P3D:

I'd like to know the estimated apogee.  I've heard that the apogee that has 
been published is no longer best estimate, due to spacecraft weight.  If 
so, I'd like to know the present best estimate.

When attempting to calculate satellite link budgets, there is a number that 
is essential that it seems nobody ever publishes.  This is the TRANSPONDER 
GAIN.  It is easy to calculate an uplink budget, or a downlink budget, but 
to combine the two you need to know the GAIN of the transponder.  It isn't 
enough to know the size of the transponder PA, because depending on the 
transponder gain, one might not have a strong enough signal to obtain a 
fair share of that PA power.  One must have enough uplink signal to 
overcome noise in the transponder's receiver, AND ALSO enough uplink signal 
to produce a powerful enough downlink signal to overcome noise in the 
recipient's receiver on the ground.  The budget for the later has the 
transponder gain squarely in the middle of it.

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org