Echo “can be configured for simultaneous voice and data.” But to what extent does the power budget support that?
The satellite should generate up to 18 watts when in sunlight. Most of this will be available to the transmitters as the spacecraft consumes less than 1 W. At 7.5 watts of RF output the transmitters should be about 45% efficient (class AB amplifiers) which comes to 16.6 watts/transmitter or 33.3 watts. We can support that load for 10-15 minutes of activation periods on all orbits and still fully charge the battery. The battery capacity is 35 Wh so even transmitting in eclipse on every orbit with both transmitters near full power that will yield about 20% battery depth of discharge. It must be noted that we won’t know the actual power available till we get on orbit and characterize things. Also, Echo will not start out with any sort of scheduling or orbit determination software on board, so turning things on/off or changing modes automatically will be down the road a ways.
