| Author |
Message |
    
Moderator1516
Moderator
Username: Moderator1516
Post Number: 339
Registered: 8-2005
| | Posted on Sunday, October 08, 2006 - 2:27 pm: | 
|
how does nasa communicate such long distance,and i believe it is line of sight,the moon is almost 239thousand miles away,and here it is with out the help of skip i cant get across the united states
moderator1516 |
Captian_radio
Member
Username: Captian_radio
Post Number: 52
Registered: 9-2004
| | Posted on Sunday, October 08, 2006 - 6:31 pm: |
|
nasa uses frequencies that are high in the spectrum,they arent affected by the ionsphere, they dont bend back to earth they pass through and off to deep space nine.Amatures use similar freqs to bounce signals off the moom and back this is EME earth moon earth,these sigs will pass through the inosphere or skip layer and bounce off what ever is out there and hopefully back to earth.Funny thing tech 808 and i were discussing this today on the chat page.I have heard eme signals once at a friends place , he was trying eme on 2 meters with very big antenna and an even bigger amp, sounded very cool.
Bob CEF451 |
Tech833
Moderator
Username: Tech833
Post Number: 1482
Registered: 8-2002
| | Posted on Sunday, October 08, 2006 - 9:11 pm: |
|
Using VHF and above, radio frequency radiation passes through the Earth's atmosphere with very little attenuation.
The astronaughts often bring 2-meter ham radios on board and communicate with hams on Earth. A 5-watt 2-meter HT with a rubber duck antenna held next to a window is all it takes.
Playing with moonbounce is a lot of fun too. It's amazing when you hear your own signal come back to you delayed. Just imagine, only a fraction of a millionth of the signal you sent out into space bounced back, and it was THAT crystal clear. Just imagine how clear your signal is hitting other planets and galaxies. Really blows you mind!
Playing with VHF, UHF and above is a lot of fun and very rewarding with minimal effort. An amplifier equals nearly zero on the higher frequencies. Antenna is 99.9% of success. Even inefficient rubber-duckie antennas work well on the higher frequencies. They don't do a thing on CB or HF. |
Hotwire
Senior Member
Username: Hotwire
Post Number: 1887
Registered: 1-2005
| | Posted on Tuesday, October 10, 2006 - 1:49 pm: |
|
I would imagine that astronauts have some satellite help especially if they are out of line of sight. |
Tech237
Moderator
Username: Tech237
Post Number: 554
Registered: 4-2004
| | Posted on Wednesday, October 11, 2006 - 9:13 am: |
|
Hotwire,
No not satellite help for th Astronauts, but they do have several ground stations around the world - Australia, England just to name two.
Somewhere I have a list of frequencies used by NASA and when I get around to packing that box I'll post them for those who are interested. |
Tech833
Moderator
Username: Tech833
Post Number: 1486
Registered: 8-2002
| | Posted on Wednesday, October 11, 2006 - 9:35 am: |
|
Hotwire....
Why would they neet any SatCom help? They ARE the sattellite!!!
They do use multiple ground stations though, since they are not always line of sight to Florida or California. Those remote ground stations are linked by SatCom and land line. |
