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Hi Mick,
I don't know a lot about radio technology. But to be able to transmit at long distances with low power it is essential to not spread out the signal. Communication with the Voyager spacecrafts are done by using big disc antennas in both ends (transmitter and receiver). The Voyager 1 craft transmits with 23W and the signal take 10 hours of travel time between the antennas. Use a search engine to find the information or go to a library. Communication with the Voyager spacecrafts: https://science.howstuffworks.com/question431.htm. https://science.howstuffworks.com/question431.htm
They use a frequency range with low noise which allows for big amplification of the signal. The distance is from outside the solar system.
Regards
Ole
---In [email protected], <mkjekyll@...> wrote :
Ole,
Thanks for the link.
As I understand it in theory a maser would make perfect sense but as far as I am aware until very recently they required so much input power for so little output they were just lab curiosities until the much more efficient lasers were invented and became a useful tool.
From your knowledge of electronics and RF math without tricks such as DSP's digging into the noise floor or special totally coherent non beam expanding collimated antennas what is the amount of power required to communicate reliably day in and day out 250k miles without repeaters or satellites, just two way with lets say a pair of 28dbi gain dishes? I just want to see if my math is completely messed up.
On 6/6/2018 4:06 PM, onielsen@... mailto:onielsen@... [EVGRAY] wrote:
Hi Mick,
The RF beam must be as narrow as possible to not spread out the energy to places where it does no good. The guy I told about used a helical antenna. I don't know anything about how he did it and the power used. One way could be by using the predecessor of the LASER which was the MASER. This would transmit a thin beam of microwaves.
This Wikipedia article (https://wiki2.org/en/Earth%E2%80%93Moon%E2%80%93Earth_communication https://wiki2.org/en/Earth%E2%80%93Moon%E2%80%93Earth_communication) has a gallery of antennas used for earth moon earth communication. It tells that as low as 100W can be used when using digital signal processing.
Regards
Ole
---In [email protected] mailto:[email protected], <mkjekyll@...> mailto:mkjekyll@... wrote :
Ole,
Specifically the math is messing with my head. Either I am misunderstanding / applying the math else according to FPL calculations antenna gain and dbW something the distance of the moon should not be feasible without millions of watts of transmitter power.
Laserbounce is another story due to the reflectors and the fact a laser stays colimated enough not to disperse as quickly as does Rf.
On 6/6/2018 3:04 PM, onielsen@... mailto:onielsen@... [EVGRAY] wrote:
Hi Mick,
The problem by using the moon as a reflector could be made more efficient if placing a RF reflector just like the LASER reflectors already out there. Another way could be making a RF repeater like is done in communication satellites. It would probably be much cheaper to put up a communication satellite or to use one of the many already up there.
The surface of the moon isn't a good conductor (I guess) and it may even spread out the signal instead of reflecting it back to the transmitter like it is done with corner reflectors https://wiki2.org/en/Corner_reflector. This gives great loss of the received signal.
Regards
Ole
---In [email protected] mailto:[email protected], <mkjekyll@...> mailto:mkjekyll@... wrote :
https://www.electronics-notes.com/articles/ham_radio/amateur-propagation/moonbounce-propagation-eme.php https://www.electronics-notes.com/articles/ham_radio/amateur-propagation/moonbounce-propagation-eme.php
Here is a link for ham radio folk about EME or moonbounce radio. The path loss in best case scenarios is very high.
Can someone who knows more RF electronics theory such as Ole or Hector please comment as to how this is overcome with 1000 watt input transmitter when the maximum theoretical S/N ratio and 252 db PL should require transmitters larger than AM radio stations.
I must be missing something. Also checking the amateur radio sites for an answer.
Thanks,
Mick