Lee Maisel wrote:
James French wrote:
What are the possibilities of building a satellite that uses a Linksys WRT54GL router with a modified DD-wrt or HSMM-Mesh software as a store and forward BBS, to route a received request from one station to another station, or even to connect to a on board networked camera to receive images?
What kind of uplink power would be needed from the home station?
How fast could the speed(s) get theoretically?
How big would the antenna have to be on the craft and for the ground station to even be able to do this adequately?
Would the doppler be too much to even consider this?
Would the space environment be too harsh for something like this?
This is just something I was thinking about this morning and thought I would toss it out.
James W8ISS
THAT is an AWESOME Idea!
I don't see why it wouldn't work, I don't know if doppler is an issue though, it may not be if the modulation is FM. The antenna would not have to be big, it's 2.4Ghz
Why don't you post this on the HSMM-MESH.org web forums and get ideas?
73 Lee W5LMM
Hi James, Lee,
If you are thinking of using standard Wi-Fi as the link protocol, be aware that the timers that drive the protocol don't well work over long distances (few miles). Something about the speed of light not being fast enough. Real bummer. These would need to be adjusted, though I think the implications for a point-point connection may not be too severe.
Besides doppler shift, which could be a problem depending on how agile the ground station is, the modulation scheme (it's NOT simply FM) uses about 20 mhz of bandwidth, so you will need significant power to get the 20db S/N needed to decode anything halfway reliably. Remember, a typical AP runs 100mw on 2.4 ghz, and gets reliable communication over distances of 100's of FEET with omni antennas. Add some gain on both ends (so now you need attitude control on the satellite!), and you can go a few miles. But 100's of miles to orbit? I need someone to "do the numbers", but I bet it's not too good.
Greg KO6TH