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#226 Re: Human missions » Advanced Communications Systems - more efficient communications » 2002-09-30 10:21:18
Yeah... what I am worried about it the lack of bounce capability. let a lone the free space lost accompanied with a dust storm. the power consumption you talk about also must realize that some of those signals where going to DSN (Deep Space Network) Sites. even though S-Band is still UHF(very high UHF) Someone could use a dish if they wanted to, I suppose, don't know what would be more efficient, let alon gain issues. but the directionality would also be key. an antenna with .5 degrees look angle would need 3 db less power of an antenna that had a .7 degree look angle. If you see where I am going with this. Some antennas are shotguns. Satellites are huge shotguns, some most likely in excess of 10-15 degrees. The other thing with that 20-30 watts is bandwidth. I guarantee it is not wide enought to do voice. So.. if you could tell me how much bandwidth we could do some calculations. Also, how much above the noise floor was it? did it say?
thanks
#227 Re: Human missions » Advanced Communications Systems - more efficient communications » 2002-09-28 00:17:59
Also another point to be brought up is communication on Mars. Does anyone know where the Clarke belt on Mars is? Also with the atmosphere being the way it is, I doubt there will be much of chance for Troposcatter communications.. which is still relied upon here for short runs ( ~250 miles). I am also curious on the noise floor on Mars.. on what is filtered out by the atmosphere.. How well hf and Vhf radio may work.. Just thoughts.. ???
#228 Re: Interplanetary transportation » Liquid fission rocket » 2002-09-27 00:10:41
Well number 04 I am in the same shoes as you. I am a journeyman level Sat Communications Maintainer in the Air Force and(equal to a few years of EE with Communications training in UHF and SHF) I also have a few years of Geology too. so I know a little about lot and a lot about very little... unfortunatly.. Will try to work towards a physics degree soon though.. 
#229 Re: Human missions » Advanced Communications Systems - more efficient communications » 2002-09-24 14:52:42
Anyone thought about any ideas for improving communications. ie bandwidth increases, bandwidth effiecency 128-PSK and crazy stuff like that or polarity modulation(Is it feasible). Would like some brain teasers on this point. Also, anyone know any equations for figuring power for communications systems, was thinking about it the other day how much power it would take to transmit a one Mhz wide signal in the SHF range from 30 light years.. Ie, how much power it would need for Seti to pick up a signal.
#230 Re: Interplanetary transportation » Power Limits of Advanced Propulsion » 2002-09-24 14:07:24
While it is a lot less weight then talked about a B-1B Lancer could carry in excess of 20,000 Kg to over 50,000ft up to or in excess of Mach 1
A C-5 Can carry atleast 270,000 lbs to atleast 40,000 ft approaching Mach .77
This could theoretically save on same energy requirments, but something like a B-70 would need to be used to get any true benefit, It was capable of flying in excess of 70,000 ft with over 50,000 lbs at over Mach 3. (again weight may not be enough to prove useful. This plane was designed in the 1950's so I imagine it would be possible to have a plane that goes in excess of Mach 1 at over 70,000 feet lifting well over 100,000 lbs that could prove as a somewhat efficient reusable first stage...
Also, any good books that I could read to get myself up to speed on Orbital Mechanics?
thanks