Abstract :
Mobile SSB and FM systems are compared on the basis of the same equipment size. The influence of the speech processing on the comparative results is discussed. It is concluded that SSB may provide a somewhat better range of operation with considerable spectrum saving but the S/N ratio in strong signal areas will be poorer. My remarks will be strictly limited to the use of SSB for mobile service, voice communication in VHF band above 30 mc and not to other SSB applications. There are two major questions to answer. 1. Will SSB be suitable for VHF mobile application and how well it will perform in comparison to FM or to put it bluntly, will all FM systems become obsolete overnight? The second question is: Why bother with SSB in the first place, will it really save the frequency spectrum and provide more channels? In my paper I will try to cover the first question, the second will be only briefly mentioned; the answer to it is complex and not an obvious "yes", or "no." In comparing SSB and FM some engineers previously based the comparison either on equal transmitter peak power or equal average power, or what not; some claim that SSB is better than FM by 9 db, some think it is 20 dB or more better and some others think that it is no darn good at all. I am not questioning these figures, they are all correct, relative to the assumptions made in comparing the systems.
