Extra exam question E2A02

WhyAn inverting linear transponder reduces net Doppler shift, reverses a signal's position within the passband, and swaps upper sideband for lower sideband on the downlink, all at once. An inverting linear transponder receives on one band and retransmits on another by mixing the uplink with a local oscillator and taking the difference frequency, and that mixing process happens to flip the spectrum: it reduces net Doppler shift because uplink and downlink shifts move in opposite directions and partially cancel, it reverses where a station's signal falls within the passband, and it swaps upper sideband for lower sideband and vice versa, answer D. Each of those three effects is a genuine consequence of the same inversion, so all of them being correct together is accurate.