ABSTRACT
A satellite receives a signal from a ground transmitter – the ‘uplink’ – and re-transmits (‘reflects’) the signal to a ground receiver – the ‘downlink’. A satellite can be considered to have a number of these ‘radio mirrors’ – termed transponders. The part of the system in the sky is termed the ‘space segment’, as we saw on page 15. The signal takes a finite time to travel up to the satellite and back down to earth (referred to as satellite delay), and is around 250 ms.
