2.4GHz broadband router on satellite?
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
Lee and those who have responded so far,
Those are the questions that would need to be answered before even considering this 'novel' idea.
I use the WRT54GL as a reference since that is what I am familiar with. The WRT54GL would need to be almost redesigned because of space radiation conditions plus it may just not have enough output power to even be considered especially with trying to fit it into a microsat or smaller frame and then finding a suitable launch. Could the satellite utilize a modified 'backfire' antenna (referencing AO-40 2.4GHz antennas) that utilizes dipoles offset from the surface on every side and then use the surface of the satellite itself for gain?
As for HSMM-Mesh, this maybe the software to consider for something like this as its robust enough for what I have played with three WRT54G around my area (EN82jg), both mobile and stationary. My laptop (a Fujitsu Lifebook T4020) is sensitive enough to pick up one 54g half a mile away using just the supplied antennas and if I add a BBQ style dish (from my AO-40 reception days) to replace the supplied antenna, I can almost quadruple that range. Granted the laptop and 54g are both at ground level and have a lot of obstructions. Still have to take it out to one of the local parks to see what I can actually get for range with no buildings. With the laptop being so sensitive, I can connect to the local McD's free wi-fi almost half a mile away better than I can my d-link router in the basement.
As for frequency usage, going by the 'slide-band' chart (available at http://www.hsmm-mesh.org), there are 6 available 'channels' that fall in the satellite sub-band the way I am interpreting FCC rules. If the 'slide-band ' crystal modification is done, that gives 4 'channels' for use. Something to consider there about 'channel' hopping in the software.
Greg, KO6TH, brings up about the timing protocols. Maybe the HSMM group or TAPR would consider looking at the protocols and maybe modify them much like AX.25 was done for packet back in the 1980's.
Mark and Drew bring up about noise levels being unacceptable on a few of the lower bands. This might be mitigated with the use of the 'slide-band' modification by changing out the 20MHz crystal for a more appropriate frequency. As I noted earlier, more about the 'slide-band' mod for the 54GL is at the hsmm-mesh pages.
So if some of these obstacles can be 'overcome', would this be a 'viable' consideration? Could something like this be utilized to gain the faster input speeds that are wanted for uploading/ downloading images, files, and maybe store and forward systems that could tie into the regional packet networks utilizing JNOS 2.0, WinLink, and FBB.
I just miss having something that is more than just APRS-related on the satellites. This in no way is a knock on the present 1k2 sats, its just that my KPC-9612 has been VERY under-utilized since the mid-1990's and I miss having that fun :(
I am not a rocket scientist, electrical engineer, or a sat designer. These are just personal thoughts to see if this 'idea' is even feasible. My thoughts could be seriously flawed and skewed and totally 'out of this world' to say. For all I know, this might be one of those bright ideas that would work better with a placement on the lunar surface as long as it doesn't interfere with EME work and can survive the harsh environment there. That would be a TOTALLY separate discussion in itself alone.
James W8ISS ===== On Tue, 2013-02-19 at 10:12 -0500, 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
Hello James, I just wanted to throw my two cents in on the protocols. I'm not sure about the need for AX.25 implementation. The 802.11(Wi-Fi) standard should server the purpose needed. AX.25 is a considerably limited protocol. Low speeds, limited error correction, and frankly, it defeats the purpose of putting a wifi router in orbit to begin with. One key feature of 802.11 is its ability to operate in less than ideal conditions. The protocol natively supports error correction, multiple simultaneous users, and can avoid data collision with "carrier-sense" technology. Also, long distance shouldn't be too large a concern. I seem to remember reading about a successful experiment involving high altitude balloons. I may too not be entirely accurate on the above, I'm still in college for a networking degree. I'm just going on what I've learned so far.
Joshua KJ4VYR
On Fri, Feb 22, 2013 at 3:06 PM, James French [email protected] wrote:
Lee and those who have responded so far,
Those are the questions that would need to be answered before even considering this 'novel' idea.
I use the WRT54GL as a reference since that is what I am familiar with. The WRT54GL would need to be almost redesigned because of space radiation conditions plus it may just not have enough output power to even be considered especially with trying to fit it into a microsat or smaller frame and then finding a suitable launch. Could the satellite utilize a modified 'backfire' antenna (referencing AO-40 2.4GHz antennas) that utilizes dipoles offset from the surface on every side and then use the surface of the satellite itself for gain?
As for HSMM-Mesh, this maybe the software to consider for something like this as its robust enough for what I have played with three WRT54G around my area (EN82jg), both mobile and stationary. My laptop (a Fujitsu Lifebook T4020) is sensitive enough to pick up one 54g half a mile away using just the supplied antennas and if I add a BBQ style dish (from my AO-40 reception days) to replace the supplied antenna, I can almost quadruple that range. Granted the laptop and 54g are both at ground level and have a lot of obstructions. Still have to take it out to one of the local parks to see what I can actually get for range with no buildings. With the laptop being so sensitive, I can connect to the local McD's free wi-fi almost half a mile away better than I can my d-link router in the basement.
As for frequency usage, going by the 'slide-band' chart (available at http://www.hsmm-mesh.org), there are 6 available 'channels' that fall in the satellite sub-band the way I am interpreting FCC rules. If the 'slide-band ' crystal modification is done, that gives 4 'channels' for use. Something to consider there about 'channel' hopping in the software.
Greg, KO6TH, brings up about the timing protocols. Maybe the HSMM group or TAPR would consider looking at the protocols and maybe modify them much like AX.25 was done for packet back in the 1980's.
Mark and Drew bring up about noise levels being unacceptable on a few of the lower bands. This might be mitigated with the use of the 'slide-band' modification by changing out the 20MHz crystal for a more appropriate frequency. As I noted earlier, more about the 'slide-band' mod for the 54GL is at the hsmm-mesh pages.
So if some of these obstacles can be 'overcome', would this be a 'viable' consideration? Could something like this be utilized to gain the faster input speeds that are wanted for uploading/ downloading images, files, and maybe store and forward systems that could tie into the regional packet networks utilizing JNOS 2.0, WinLink, and FBB.
I just miss having something that is more than just APRS-related on the satellites. This in no way is a knock on the present 1k2 sats, its just that my KPC-9612 has been VERY under-utilized since the mid-1990's and I miss having that fun :(
I am not a rocket scientist, electrical engineer, or a sat designer. These are just personal thoughts to see if this 'idea' is even feasible. My thoughts could be seriously flawed and skewed and totally 'out of this world' to say. For all I know, this might be one of those bright ideas that would work better with a placement on the lunar surface as long as it doesn't interfere with EME work and can survive the harsh environment there. That would be a TOTALLY separate discussion in itself alone.
James W8ISS
On Tue, 2013-02-19 at 10:12 -0500, 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
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Could a gain antenna be incorporated into a gradient boom for aiming?
Roger WA1KAT
On 2/22/2013 3:06 PM, James French wrote:
Lee and those who have responded so far,
Those are the questions that would need to be answered before even considering this 'novel' idea. Could the satellite utilize a modified 'backfire' antenna (referencing AO-40 2.4GHz antennas) that utilizes dipoles offset from the surface on every side and then use the surface of the satellite itself for gain?
--- On Fri, 22/2/13, Joshua Abraham [email protected] wrote:
I seem to remember reading about a successful experiment involving high altitude balloons.
See http://www.nrl.navy.mil/content_images/07Information_Rupar.pdf
73 Trevor M5AKA
There has been some work done with wireless routers and amplifiers in several balloon flights in association with the Wx bureau. A group which I am a part of got the equivalent of an SBIR from a federal agency to do this work (plus they helped us get on the balloons. There is no secret here really, the various formulas associated with link margins etc "work" (grin) and the links were quite solid AND city RF made little difference. Directional arrays on the ground are ones friend and even near "WiFI" hotspots the systems worked well (that was part of the test).
The main issue for a satellite particularly one in LEO is going to be doppler shift. Farther out of course the shift is less but link margin is more difficult.
The frequencies are different but we are now using TACSAT 4 for some test. Robert WB5MZO
Date: Fri, 22 Feb 2013 21:36:01 +0000 From: [email protected] To: [email protected] Subject: [amsat-bb] Re: 2.4GHz broadband router on satellite?
--- On Fri, 22/2/13, Joshua Abraham [email protected] wrote:
I seem to remember reading about a successful experiment involving high altitude balloons.
See http://www.nrl.navy.mil/content_images/07Information_Rupar.pdf
73 Trevor M5AKA
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (5)
-
James French -
Joshua Abraham -
R Oler -
Roger -
Trevor .