Consider the following statements regarding communication by geostationary satellites:
1. A back and forth telephone transmission involves nearly half a second.
2. Since the ground station antenna points towards a fixed direction, large corrections are necessary to compensate for orbital variation and atmospheric diffraction.
3. Since the satellite antenna is limited in size, the earth are illuminated by the beam is also small.
4. As there is no Doppler shift, no correction for frequency is necessary.
Select the correct answer out of these statements.