K(U)- VS C-BAND AND DIGITAL VS ANALOG TELEVISION TRANSMISSION IN A TROPICAL CLIMATE

This paper analyses the K(u)-band versus C-band transmission for digit al and/or analogue TV, keeping in mind K(u)-band attenuation in the tr opical climate as a function of earth-station antenna elevation angle. The analysis is done for the case that adjacent satellites illuminate the same converage area and that interfering signals are of same e.i. r.p. and spectral make-up. It is shown that a multiplex of compressed digital carriers requires smaller receiving antennas than a single ana logue TV carrier. It turns out that because of low power requirements of the compressed digital carrier and/or for high e.i.r.p. values, the earth-station antenna diameter is interference limited. Below the int erference limit the aperture can only be reduced by applying an ellipt ical area to provide for a narrower beamwidth along the geostationary arc.