Brian Lloyd wrote: For example: distance from Earth to Moon = ~384000km, then :
> >> 41 dBm EIRP (20dBm + 21dBi) at his house. > >> - 108 dB Free space loss - first link Free space loss from Earth to Moon = -227dB > >> + 18 dBi antenna gain on the mountain. > >> + 18 dBi antenna gain on the mountain. > >> - 118 dB Free space loss - second link. Free space loss from Moon to Earth = -227dB > >> + 24 dBi antenna gain at ISP. > >> ========= > >> - 125 dBm total : - 454 dB Free space loss ... сommunication impossible, even if to use "1Hz or less bandwidth" & "symbol rate is about one symbol every 10 seconds" -Ivan > > > > > > According to these calculate communication > > through the moon is impossible ... > > > > Really communication is, > > even if to use 10W > > Forgive me if I misunderstood your message but let me reply to what I think you are > saying. > > Yes, communications to the moon is possible with low power. Hams do it with 10W but > with more antenna gain. They also use 1Hz or less bandwidth. The symbol rate is > about one symbol every 10 seconds or so. If you are going to make a comparison, > please be sure that the comparison is valid. > > If you want to increase the bit rate you need to either increase the bandwidth or > increase the signal-to-noise ratio (Shannon's theorem). Increasing bandwidth > increases noise admittance and raises the noise energy in the passband thus > requiring a greater absolute signal strength to overcome more background thermal > noise energy in the increased passband. This is why you see the required signal > decrease as you decrease the bit rate with 802.11b. Sure, if you want to send data > at 1 baud you can use a LOT less signal. Is that what you are shooting for? > > TANSTAAFL (there ain't no such thing as a free lunch). > > -- > Brian Lloyd 6501 Red Hook Plaza > [EMAIL PROTECTED] Suite 201 > http://www.lloyd.com St. Thomas, VI 00802 > +1.340.998.9447 (voice) +1.360.838.9669 (fax) > > -- > general wireless list, a bawug thing <http://www.bawug.org/> > [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
