144 Mhz contact made using ISS as passive reflector
http://www.southgatearc.org/news/december2007/bouncing_signals_off_iss.htm
Congrats to the DF2ZC and DH7FB on making a CW contact using the ISS as a passive reflector!
It's interesting that in the article Bernd discusses the problems with using PSK due to doppler, as well as manually having to set az and el. It seems to me that a couple of well equipped computer-controlled earth stations should be able to do this using One True Frequency principles with PSK. Wish I had the equipment to give it a try.
Bob - AE6RV
This is pretty amazing. What about the viability of 'fast' modes such as FSK441?
I seem to recall somebody trying this with Mir (RIP) back in the day.
Bob Stewart wrote:
http://www.southgatearc.org/news/december2007/bouncing_signals_off_iss.htm
Congrats to the DF2ZC and DH7FB on making a CW contact using the ISS as a passive reflector!
I thought of doing this back in October, when all the Sputnik-1 / early satellite discussion was happening. Echo-1, and all that. But, I would think that NASA (if not the crew) would frown on a bunch of folks on the ground hurling a few megawatts EIRP at their home in outer space. If Bob had to have a bazillion levels of safety in place for the little PCSAT-2 transmitter, I would think this would be right up there in the safety category, no?
I haven't done the math yet... Are we far enough away that 1/x**2 saves us?
Greg KO6TH
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Date: Tue, 11 Dec 2007 11:32:50 -0800 From: bob@evoria.net To: amsat-bb@amsat.org Subject: [amsat-bb] 144 Mhz contact made using ISS as passive reflector
http://www.southgatearc.org/news/december2007/bouncing_signals_off_iss.htm
Congrats to the DF2ZC and DH7FB on making a CW contact using the ISS as a passive reflector!
It's interesting that in the article Bernd discusses the problems with using PSK due to doppler, as well as manually having to set az and el. It seems to me that a couple of well equipped computer-controlled earth stations should be able to do this using One True Frequency principles with PSK. Wish I had the equipment to give it a try.
Bob - AE6RV _______________________________________________ Sent via AMSAT-BB@amsat.org. 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
_________________________________________________________________ Share life as it happens with the new Windows Live. http://www.windowslive.com/share.html?ocid=TXT_TAGHM_Wave2_sharelife_122007
Already discussed on the MoonNet reflector:
Subject: Re: [Moon-net] ISS communicaton NOT a GOOD idea !!!!
Hi Steve ,
Even our "big" signals are small when they arrive up there . Assume you use 1kw and 20dB antenna gain , this makes an ERP of 100kw or 80 dBm ERP, once your signal is +/- 600km further then you have about -130dB less power due the path loss (on 144MHz) , this means that your signal arrives at ISS with a level of -50dBm , so nothing to worry about .
Best regards, Kenny ON4DPX
At 07:49 PM 12/11/2007, Greg D. wrote:
I thought of doing this back in October, when all the Sputnik-1 / early satellite discussion was happening. Echo-1, and all that. But, I would think that NASA (if not the crew) would frown on a bunch of folks on the ground hurling a few megawatts EIRP at their home in outer space. If Bob had to have a bazillion levels of safety in place for the little PCSAT-2 transmitter, I would think this would be right up there in the safety category, no?
I haven't done the math yet... Are we far enough away that 1/x**2 saves us?
Greg KO6TH
Date: Tue, 11 Dec 2007 11:32:50 -0800 From: bob@evoria.net To: amsat-bb@amsat.org Subject: [amsat-bb] 144 Mhz contact made using ISS as passive reflector
http://www.southgatearc.org/news/december2007/bouncing_signals_off_iss.htm
Congrats to the DF2ZC and DH7FB on making a CW contact using the ISS as a passive reflector!
It's interesting that in the article Bernd discusses the problems with using PSK due to doppler, as well as manually having to set az and el. It seems to me that a couple of well equipped computer-controlled earth stations should be able to do this using One True Frequency principles with PSK. Wish I had the equipment to give it a try.
Bob - AE6RV _______________________________________________ Sent via AMSAT-BB@amsat.org. 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
Share life as it happens with the new Windows Live. http://www.windowslive.com/share.html?ocid=TXT_TAGHM_Wave2_sharelife_122007 _______________________________________________ Sent via AMSAT-BB@amsat.org. 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
73, Ed - KL7UW ====================================== BP40IQ 50-MHz - 10-GHz www.kl7uw.com 144-EME: FT-847, mgf-1801, 4x-xpol-20, 185w DUBUS Magazine USA Rep dubususa@hotmail.com ======================================
Yep, think the HAM signal would be minute compared to what it gets hit with from the NAVSPASUR, USA Radar on 216.980Mhz !!
Mark VK3MJ Geelong, Australia.
-------------------------------------------------------------------------------- Already discussed on the MoonNet reflector:
Subject: Re: [Moon-net] ISS communicaton NOT a GOOD idea !!!!
Hi Steve ,
Even our "big" signals are small when they arrive up there . Assume you use 1kw and 20dB antenna gain , this makes an ERP of 100kw or 80 dBm ERP, once your signal is +/- 600km further then you have about -130dB less power due the path loss (on 144MHz) , this means that your signal arrives at ISS with a level of -50dBm , so nothing to worry about .
Best regards, Kenny ON4DPX
At 07:49 PM 12/11/2007, Greg D. wrote:
I thought of doing this back in October, when all the Sputnik-1 / early satellite discussion was happening. Echo-1, and all that. But, I would think that NASA (if not the crew) would frown on a bunch of folks on the ground hurling a few megawatts EIRP at their home in outer space. If Bob had to have a bazillion levels of safety in place for the little PCSAT-2 transmitter, I would think this would be right up there in the safety category, no?
I haven't done the math yet... Are we far enough away that 1/x**2 saves us?
Greg KO6TH
..."big" signals are small when they arrive up there . Assume 1kw and 20dB antenna gain... makes an ERP of 100kw... once your signal is about 600km further then you have -50dBm , so nothing to worry about .
Yes, although - 50dBm is a very "strong" signal... 100 million times more power than the sensitivity of a good receiver, it is still only one one-hundred-millionth of a watt. Couldn't even harm a flea's eyeball. And even a hamtronics receiver has over 100 dBm rejection just 15 KHz away.
So as long as it is not transmitted on exactly a channel presently in use by an ISS receiver, then there is no problem.
Or something like that. Bob
At 11:49 PM 12/11/2007, Greg D. wrote:
I thought of doing this back in October, when all the Sputnik-1 / early satellite discussion was happening. Echo-1, and all that. But, I would think that NASA (if not the crew) would frown on a bunch of folks on the ground hurling a few megawatts EIRP at their home in outer space. If Bob had to have a bazillion levels of safety in place for the little PCSAT-2 transmitter, I would think this would be right up there in the safety category, no?
I haven't done the math yet... Are we far enough away that 1/x**2 saves us?
Greg KO6TH
Hi Greg,
The ISS flies through the 217 MHz AFSSS Radar Fence 6 times a day and it has an ERP of over 6,000 megawatts. It is only for about a second at the peak but even the sidelobes are much higher than anything a ham station could possibly come up with - no problem.
73, Tony AA2TX
The ISS flies through the 216.98 MHz AFSSS Radar Fence across the southern USA 6 times a day and it has an ERP of over 6,000 megawatts. It is only for about a second at the peak but even the sidelobes are much higher than anything a ham station could possibly come up with...
Bit of history on the sidelobes: On the AMSAT-BB you might remember our PANIC about 6 months ago trying to find a good OSCAR class station in the Southern states during the final days of the RAFT satellite (Radar Fence Transponder) to command the radar receiver ON at exactly the time of passage through the fence beam.
We could not do it here from Maryland because the satellite was too low when it passed through that one second beam. But darned-it-all. When we finally did get a student at UC Irvine (KF6RDB) to turn it on, of course we found out all about those sidelobes! He heard the transmitter through most of the pass, not just the one second when it went through the beam...
If we had thought about that, we could have been doing all kinds of neat testing from here throughout the mission... Oh well. Live and learn. The sidelobes would have to have been attenuated by milliions to not be heard. Even 50 dB down, is still very strong on VHF... Conidering the 100 meggawatts of transmitter.
The ANDE re-entry campaign is getting HOT. So lets capture that telemetry and feed it to the APRS-IS...
Bob, WB4APR
participants (7)
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Anthony Monteiro -
Bob Stewart -
Edward Cole -
Greg D. -
jonny 290 -
Mark Jeffrey -
Robert Bruninga