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On Sep 16, 3:33*pm, John Smith wrote:
wrote: ... No, they are declining if you are talking about anything over 200m. They are also losing spectrum for example in 40m to amateurs. No, the AM Broadcast Band is the MW band, ~.5Mc to ~1.800Mc ... not related to happenings in the 40m amateur band at all ... But I qualified the statement by saying anything above 200m (in wavelegth) which you faithfully quoted above. Minus 2 points for John. John, Quiz Question: Suppose you tried to modulate a 14 Khz carrier with a 50MHz digital signal. Would that be possible? (Y/N) Where would you locate the side bands? (________ and ________) A nut would attempt that ... others would modulate the 50Mhz signal ... and 49.993 to 50.007 ... in a perfect world. OK, now, since 50MHz is being modulated, how much bandwidth will each sideband occupy? Cannot be done, John. HF frequencies can only handle insignificant amounts of data information making them useless in today's digital age. THAT is why (to answer the original question) nobody gives a damn about small antennas on HF frequencies. The data we are transferring today goes far beyond a simple 10KHz voice communication on a small section of spectrum. Even a single analog TV channel occupies 5MHz which I think would cover the entire HF spectrum if it were tried. There are some exceptional HF digital applications which society can find useful in extremely limited applications such as sail mail but even that is quite disruptive due to the wide chunk of HF it occupies for a single email transmission. Really, you need a beginners group ... :-( *Won't your mom play with you today? RRAP IS a beginners group John. |
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