Satellite Communications/Power spectral density
My question its about the definition of the Power Spectral Density
in relations of satellite communications and
I had found to calculated the PSD for the downlink that is
PSDdownlink= Downlink EIRP - 10 *log (Symbol Rate)
But in many link budget calculations there are also PSD uplink
I want to know how to calculate the PSD from de uplink
Im looking forward for your answer
Have I nice day
Dear Mr Eduardo,
Satellite link budgets are done based on the satellite parameters and that helps in design of sufficient link availability from Transmitting Earth Station to Receiver Earth Stations. The parameters you mentioned are basically for design of Earth Station Receive System for may be TV reception (DTH for example). Normally transmitting Earth stations consider EIRP of the Uplink and the SPFD of the Satellite Specification for safety and margin. Uplink is not supposed to have higher EIRP because that is dangerous for onboard transponder. But in downlink D/L EIRP of the satellite along with Path loss will enable us to decide as to what type of antenna configuration and LNB design is to be done. So the important parameter for downlink is D/L EIRP is important as your equaition indicates.
There is no restriction for handling any of the mentioned parameters for considering but LINK Budget has to be made for design of Earth Station parameters and protection of Satellite parameters from going to saturation or damaging the Xponder.
By the by the formula for PSD is same for up and links: it is same as Radar equation. But SPF I mentioned earlier is Saturated PFD which is Satellite designer's specification. PFD depends on the Range and EIRP as well as Smbol rate.