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August 10th 04, 04:46 AM
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In article , Leo
writes: On 09 Aug 2004 23:45:24 GMT, (Len Over 21) wrote: In article , (N2EY) writes: (N2EY) wrote in message ... In article , Robert Casey writes: Contests working Earth-Mars contacts should be interesting, when you remember that speed'o light means that radio signals take about 5 to 15 minutes one way to make the trip... If my math is right, the one-way transmission time works out to between 188 seconds at closest approach to 688 seconds maximum. Well, it's not correct. The 188 seconds is pretty close but the 688 is way off because I added the Earth orbit radius rather than diameter. Or perhaps grabbed the distance data off the wrong website?  Nah...just Internet QRM...he was reading video instead of morse. :-) Oh, my! Had anyone else come up with those numbers you would have sent many a multi-screen message accosting them of error-prone perfidy! :-) I can see the reply now: "Wrong again, ..xxx.......", followed by the usual Jim-style rub-the-nose-in-it verbiage. Plus a nice little macro to insert in other, later messages, claiming that the error-maker "always made errors" and isn't trustworthy and may not use deoderant... Here's a more exact calculation: Per NASA website, the Earth's orbit varies from 149.5 to 149.7 million kilometres and Mars' orbit varies from 204.52 to 246.28 million kilometres. The closest the two planets approach is 204.52 - 149.7 = 54.82 million kilometres The farthest apart they get is 246.28 + 149.7 = 395.98 million kilometres Using 0.3 million km/sec (that's 300,000,000 metres/sec) as the speed of light, we get: 54.82 / 0.3 = 183 sec (3 minutes 3 seconds) 395.98 / 0.3 = 1320 sec (22 minutes 0 seconds) give or take...... What, no EXACTNESS? Speed of light isn't EXACTLY that nice round figure. Tsk, tsk. Precision is for others. True, but the unique criticsm is HIS... :-) But you can count on contest ops to figure a way to make that work. Use the transmission time as a 'buffer' of sorts. Not a problem. Ingenious use of the delay interval would permit pretty good contest rates. Of course the ability to work duplex would be a plus. I am non-plussed. With a 44 minute round-trip time you wouldn't need any sort of T/R switch, just solder some lands on a PCB to do the same job to go from Rx to Tx and back again. :-) For rag chewing, contacts between fixed nonpolar stations on each planet up to about 12 hours long are possible if the locations are just right at both ends. You could WEAVE the rag material, cut it to shape, sew it up in the time of those contacts... :- No problem, though, for someone who takes 48 hours to reply to this little Usenet-based QSO - and fails to reply in context of the thread at that. Think of it as "a buffer." :-) "I just noticed that I was incorrect - all by myself!" Duh. Well, at least he NOTICED... He took the time out to look...away from Worked All Usenet logging... SO2R is just the beginning. Of course the reason no one - professional or amateur - has been awarded the Elser-Mathes Cup is because it requires operators at both ends of the QSO. Human space programs won't be in a position to do that for decades yet. Ah! One of the remarkable OBVIOUS statements! :-) And a brilliant one at that.....you need someone on the other end of a QSO? Sunnavagun! He could have called for the comic strip character "Obviousman!" I hearby nominate you for three or four votes in the Department of Redundancy Department. But not the Department of Mathematics. I keep having the crazy idea that a relative was working at JPL when they had that conversion error on a probe a while back. The one that failed due to the wrong constant or something, metric instead of english... Nah. Okay, now what is the PATH LOSS and what kind of Tx power is needed at each end for a given S:N ratio? Can you get by on amateur radio power levels? Without violating any of the regulations? How about Doppler Shift? How much? LHA / WMD |
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