S band and Eagle: an appeal for a higher level discussion
There has been a recent restatement of disappointment regarding the Eagle design committee's recent choice to use S band as an uplink not a downlink. Note that the next two HEO's scheduled to launch *will* have S band downlinks, so there's no worry that people like I, who live in radio quiet areas, will be unable to use our developing S band equipment in the future.
As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.
The design team have said again and again on this list that they would welcome contradicting evidence that is cogent, and I, for one, believe them. They're our volunteers, and they deserve our support. I can't provide that contradicting evidence: I'm not skilled or qualified. But I can assess an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point.
Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess their work, check their assumptions, present cogent opposing arguments. There is some thought that a dish antenna properly implemented will overcome the obstacles described by the design team. Let's model this. Or those who live in heavy 802.11b environments, do some experiements with terrestrial links (which I suppose could be assumed worse than earth/sky). Who knows? Maybe it's all like my last tax return, where a missed decimal point made me think I'd have to take out a second mortgage to pay our taxes :-) This list and the wiki exist so that we can undertake that sort of dialogue, and for my part, it is my favorite part of participation in AMSAT.
Some have suggested that Eagle fly with an S-band downlink on the off chance that it *does* work despite the theory; others, that we survey the members to see what they'd like. I fully support the design teams rejection of the former approach. Launch weight is very expensive and the kitchen sink approach is not to my mind sensible. As to the latter, a survey presumably pertains only to *working* bands, not ones that are polluted out of existance.
It's human nature for us more readily to see our misfortunes as caused by the malace of others, but I think we should strongly avoid terms like "bait and switch". We'll get much further if we all assume the goodwill of everyone involved.
73, Bruce VE9QRP
I have to agree with Bruce, however I don't take statements made by Bob McGwier (N4HY) (see below) for face value.
Quote by Bob(email to Amsat-bb on Tue 25/07/2006): "In upcoming journal articles and in Eaglepedia documents showing the detailed calculations upon which our statements are based" Quote End
It is important that the data are presented, discussed, accepted or thrown out.
The main problem with the whole discussion is that the majority of folks have NOT seen the data. In addition, if the data are as sound as they are portrait, why is AMSAT-DL not believing in them and is including S-band as a downlink. How is the discussion between ANSAT-NA and AMSAT-DL going on this?
The lack of transparency is concerning and Eaglepedia is just an empty word if key documents and information is not published especially if it is available. Waiting for journal articles to come does not help. At the same time Eaglepedia still has the now "old" mechanical design specs and information on the S-band TX transponder available with no indication that both are obsolete.
73, Stefan VE4NSA
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Bruce Robertson Sent: September 7, 2006 5:06 PM To: amsat-bb@amsat.org Subject: [amsat-bb] S band and Eagle: an appeal for a higher level discussion
....As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.....
Hi mode-S users:
I've read the comments (and their are quite a few...hint!), before adding my opinions.
First of all P3E has a much closer (we hope) launch date and is much further down the road in construction. I'm guessing they didnot anticipate that the WiFi generated noise floor posed a significant problem. Perhaps they can provide a larger mode-S ERP (I haven't compared spec's between the original Eagle and P3E). In any case, I am glad that P3E will fly both mode-S and Mode-L...and then we will see the "truth" in the Eagle engineering projections!
I wrote Bob McGwier (N4HY) soon after the referenced presentation was put out as a web-link (I believe it was slated to be presented at this years symposium, so was not intended to be pre-released). But many of us read it and discovered the major project changes that have been decided by the design team (dion't you think major shifts in design ought to have some public comment input ...i.e the users).
I proposed that the mode-S translator (S2) be flown as a contingency module to the beacon Tx (S1, I believe) and tested in orbit as a linear transponder. If the noise floor issue is found to be a problem then the module would just sit in standby (in case of failure of S1). Bob rejected that proposal.
Now, I'm hearing folks talk about the C-C Rider project but that has also been scrapped (at least as a 5-GHz in-band transponder) according to the presentation. What I understood was that mode-C would be used for digital-voice and video downlink with mode-S uplink.
BTW Eaglepedia does not reflect any of the recent design changes. An considerable portion is only outline with no content. The general membership will be challenged to follow the evolution of design (meetings) in order to discover what is the current version of the project. I guess we will see in time how that Eaglepedia works out.
Unless the membership (read this as users...quite a few with recent AO-40 experience) can sway the design, I see big issues looming for Amsat-NA "management". I for one will use the mode-UV transponder on Eagle and mode-LS on P3E. Since I will be on social security by the time Eagle is launched, I have little prospects for funding new mw bands. But we will see!
one users opinion, Ed - KL7UW
At 06:57 PM 9/7/2006 -0500, Stefan Wagener wrote:
I have to agree with Bruce, however I don't take statements made by Bob McGwier (N4HY) (see below) for face value.
Quote by Bob(email to Amsat-bb on Tue 25/07/2006): "In upcoming journal articles and in Eaglepedia documents showing the detailed calculations upon which our statements are based" Quote End
It is important that the data are presented, discussed, accepted or thrown out.
The main problem with the whole discussion is that the majority of folks have NOT seen the data. In addition, if the data are as sound as they are portrait, why is AMSAT-DL not believing in them and is including S-band as a downlink. How is the discussion between ANSAT-NA and AMSAT-DL going on this?
The lack of transparency is concerning and Eaglepedia is just an empty word if key documents and information is not published especially if it is available. Waiting for journal articles to come does not help. At the same time Eaglepedia still has the now "old" mechanical design specs and information on the S-band TX transponder available with no indication that both are obsolete.
73, Stefan VE4NSA
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Bruce Robertson Sent: September 7, 2006 5:06 PM To: amsat-bb@amsat.org Subject: [amsat-bb] S band and Eagle: an appeal for a higher level discussion
....As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.....
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's, Ed - KL7UW =================================== BP40iq, Nikiski, AK http://www.qsl.net/al7eb Amsat #3212 Modes: V - U - L - S ===================================
----- Original Message ----- From: "Stefan Wagener" stefan_wagener@hotmail.com To: brobertson@mta.ca; amsat-bb@amsat.org Sent: Friday, September 08, 2006 1:57 AM Subject: [amsat-bb] S band and Eagle: an appeal for more transparency (was Sband and Eagle: an appeal for a higher level discussion)
The main problem with the whole discussion is that the majority of folks have NOT seen the data. In addition, if the data are as sound as they are portrait, why is AMSAT-DL not believing in them and is including S-band as
a
downlink. How is the discussion between ANSAT-NA and AMSAT-DL going on
this?
73, Stefan VE4NSA
Hi Stefan, VE4NSA
The reverse is true. If the result of the S band as a downlink on AO40 was extremely succesfull why AMSAT-NA is not believing in AMSAT-DL ? The decision of AMSAT-DL to reuse the S band for downlink of P3E is based on already experimented facts using AO40 and there is no question about that. Is someone in condition to demonstrate that the S band of AO40 was a catastrophical affair ? Don't worry about because if P3E will be succesfull in orbit at the end of 2007 than the S band as a downlink will be again the voice of truth.
Best 73" de
i8CVS Domenico
Excellent point,
and I should use my spell checker more often. "Portrait" should have been "portrayed".
:-)
73, Stefan VE4NSA
-----Original Message----- From: i8cvs [mailto:domenico.i8cvs@tin.it] Sent: September 7, 2006 9:45 PM To: Stefan Wagener; brobertson@mta.ca; AMSAT-BB Subject: Re: [amsat-bb] S band and Eagle: an appeal for more transparency (was Sband and Eagle: an appeal for a higher level discussion)
----- Original Message ----- From: "Stefan Wagener" stefan_wagener@hotmail.com To: brobertson@mta.ca; amsat-bb@amsat.org Sent: Friday, September 08, 2006 1:57 AM Subject: [amsat-bb] S band and Eagle: an appeal for more transparency (was Sband and Eagle: an appeal for a higher level discussion)
The main problem with the whole discussion is that the majority of folks have NOT seen the data. In addition, if the data are as sound as they are portrait, why is AMSAT-DL not believing in them and is including S-band as
a
downlink. How is the discussion between ANSAT-NA and AMSAT-DL going on
this?
73, Stefan VE4NSA
Hi Stefan, VE4NSA
The reverse is true. If the result of the S band as a downlink on AO40 was extremely succesfull why AMSAT-NA is not believing in AMSAT-DL ? The decision of AMSAT-DL to reuse the S band for downlink of P3E is based on already experimented facts using AO40 and there is no question about that. Is someone in condition to demonstrate that the S band of AO40 was a catastrophical affair ? Don't worry about because if P3E will be succesfull in orbit at the end of 2007 than the S band as a downlink will be again the voice of truth.
Best 73" de
i8CVS Domenico
Bruce, While you bring up some good points in your message I feel there are questions that remain in need of answering.
The first question that I have is where is all this data that was used to produce such a theory of S-band pollution being too great for a HEO? I've seen data that I agree with that says that S-band uplinks would essentially be deaf on a HEO due to the rise in the noise floor from all of the non-licensed networks and such but that noise floor comes from millions of such devices. One would never have to put up with that much interference at their home stations. Until I see research data that supports such a theory I cannot possibly stand behind such a decision to cripple our next satellite.
Why should we buy a product that doesn't meet our needs and wants? I certainly wouldn't go out and purchase anything just because someone else wanted me to. My hard earned money goes into the products that fulfill my wants, needs, and desires. With S-band going away, and another project possibly being scrubbed as well, I'm seriously considering throwing my support and money towards the P3E project which has an outstanding lineup of experimental bands along with the more traditional ones on board.
Too bad this information didn't come out earlier as I'm sure it would have been a great discussion piece for those that were running for Board positions. I wonder how many Board members would support the decision of taking S-band off the future birds. Members of the Board should take note and realize that their time is coming to end with these kind of decisions being made. We pay the money to support AMSAT now where is their support back to us?
Eric KF4OTN
Bruce Robertson wrote:
There has been a recent restatement of disappointment regarding the Eagle design committee's recent choice to use S band as an uplink not a downlink. Note that the next two HEO's scheduled to launch *will* have S band downlinks, so there's no worry that people like I, who live in radio quiet areas, will be unable to use our developing S band equipment in the future.
As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.
The design team have said again and again on this list that they would welcome contradicting evidence that is cogent, and I, for one, believe them. They're our volunteers, and they deserve our support. I can't provide that contradicting evidence: I'm not skilled or qualified. But I can assess an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point.
Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess their work, check their assumptions, present cogent opposing arguments. There is some thought that a dish antenna properly implemented will overcome the obstacles described by the design team. Let's model this. Or those who live in heavy 802.11b environments, do some experiements with terrestrial links (which I suppose could be assumed worse than earth/sky). Who knows? Maybe it's all like my last tax return, where a missed decimal point made me think I'd have to take out a second mortgage to pay our taxes :-) This list and the wiki exist so that we can undertake that sort of dialogue, and for my part, it is my favorite part of participation in AMSAT.
Some have suggested that Eagle fly with an S-band downlink on the off chance that it *does* work despite the theory; others, that we survey the members to see what they'd like. I fully support the design teams rejection of the former approach. Launch weight is very expensive and the kitchen sink approach is not to my mind sensible. As to the latter, a survey presumably pertains only to *working* bands, not ones that are polluted out of existance.
It's human nature for us more readily to see our misfortunes as caused by the malace of others, but I think we should strongly avoid terms like "bait and switch". We'll get much further if we all assume the goodwill of everyone involved.
73, Bruce VE9QRP _______________________________________________ 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
If one looks at the bb archive in late July you will see a string titled "This Weekend in Minneapolis: Central States VHF Society Meeting". The subject of not having an S-band downlink on Eagle was thoroughly discussed by the likes of Bob McGwier, Tom Clarke, and Jim Sanford among others all before ballots for BOD's were due. You may not like the conclusions drawn from the previous discussion but the subject of not having an S-band downlink on Eagle is not new to this bulletin board.
Kevin Smith N3HKQ
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Eric H Christensen Sent: Thursday, September 07, 2006 8:24 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higher leveldiscussion
Bruce, While you bring up some good points in your message I feel there are questions that remain in need of answering.
The first question that I have is where is all this data that was used to produce such a theory of S-band pollution being too great for a HEO? I've seen data that I agree with that says that S-band uplinks would essentially be deaf on a HEO due to the rise in the noise floor from all of the non-licensed networks and such but that noise floor comes from millions of such devices. One would never have to put up with that much interference at their home stations. Until I see research data that supports such a theory I cannot possibly stand behind such a decision to cripple our next satellite.
Why should we buy a product that doesn't meet our needs and wants? I certainly wouldn't go out and purchase anything just because someone else wanted me to. My hard earned money goes into the products that fulfill my wants, needs, and desires. With S-band going away, and another project possibly being scrubbed as well, I'm seriously considering throwing my support and money towards the P3E project which has an outstanding lineup of experimental bands along with the more traditional ones on board.
Too bad this information didn't come out earlier as I'm sure it would have been a great discussion piece for those that were running for Board positions. I wonder how many Board members would support the decision of taking S-band off the future birds. Members of the Board should take note and realize that their time is coming to end with these kind of decisions being made. We pay the money to support AMSAT now where is their support back to us?
Eric KF4OTN
Bruce Robertson wrote:
There has been a recent restatement of disappointment regarding the Eagle design committee's recent choice to use S band as an uplink not a
downlink.
Note that the next two HEO's scheduled to launch *will* have S band downlinks, so there's no worry that people like I, who live in radio quiet areas, will be unable to use our developing S band equipment in the
future.
As I understand it, the Eagle design team have used standard predictions
of
801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I
cannot
imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would
be
a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.
The design team have said again and again on this list that they would welcome contradicting evidence that is cogent, and I, for one, believe them. They're our volunteers, and they deserve our support. I can't
provide
that contradicting evidence: I'm not skilled or qualified. But I can
assess
an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point.
Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess their work, check their assumptions, present cogent opposing arguments. There is some thought that a dish antenna properly implemented will overcome the obstacles described by the design team. Let's model this. Or those who
live
in heavy 802.11b environments, do some experiements with terrestrial links (which I suppose could be assumed worse than earth/sky). Who knows? Maybe it's all like my last tax return, where a missed decimal point made me think I'd have to take out a second mortgage to pay our taxes :-) This
list
and the wiki exist so that we can undertake that sort of dialogue, and for my part, it is my favorite part of participation in AMSAT.
Some have suggested that Eagle fly with an S-band downlink on the off chance that it *does* work despite the theory; others, that we survey the members to see what they'd like. I fully support the design teams
rejection
of the former approach. Launch weight is very expensive and the kitchen sink approach is not to my mind sensible. As to the latter, a survey presumably pertains only to *working* bands, not ones that are polluted
out
of existance.
It's human nature for us more readily to see our misfortunes as caused by the malace of others, but I think we should strongly avoid terms like
"bait
and switch". We'll get much further if we all assume the goodwill of everyone involved.
73, Bruce VE9QRP _______________________________________________ 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
_______________________________________________ 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
Bruce: Are you suggesting that "Please,, those of you who are qualified and competent" are the only folks who are worthy of a dissenting view regarding this topic? Please, that is precisely the attitude that turn folks off of AMSAT-NA, that elitist attitude has no place in a HOBBY. Particularly when we ALL contribute to the construction of the satellites. It just happens that I am a professional Network Engineer (Trainer) for a Telecommunications Company.
My background spans virtually every communications technology from DC to Daylight. I have an extensive background in EMI/RFI Labatory Testing, culminating in 35+ non-stop years in the Communications field. No I don't have any matamatical studies, what I do have is first hand empirical experience in a neighborhood where EVERY Home has at least a single 2.4GHz radiation source .
I worked AO-40 and thoroughly enjoyed the S Band downlink and have maintained the station in anticipation of continuing this activity on the HEOs. I'm not alone, I'm sure that the majority of members who have made the S Band and Investment.
Do I get interference from the IEEE 802.X devices and portable phones, yes, in the form of random clicks that are easily removed by using a noise blanker, try it works great!
What, if any studies considered that 5.2Ghz devices are taking off now and will probably eclipse the 2.4Gig interference levels. Make any argument you wish for dropping S Band from Eagle, but don't use the polluted spectrum argument, it simply doesn't hold water.
Regards, Joe, K7ZT
----- Original Message ----- From: "Bruce Robertson" broberts@mta.ca To: amsat-bb@amsat.org Sent: Thursday, September 07, 2006 5:06 Subject: [amsat-bb] S band and Eagle: an appeal for a higher level discussion
There has been a recent restatement of disappointment regarding the Eagle design committee's recent choice to use S band as an uplink not a downlink. Note that the next two HEO's scheduled to launch *will* have S band downlinks, so there's no worry that people like I, who live in radio quiet areas, will be unable to use our developing S band equipment in the future.
As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.
The design team have said again and again on this list that they would welcome contradicting evidence that is cogent, and I, for one, believe them. They're our volunteers, and they deserve our support. I can't provide that contradicting evidence: I'm not skilled or qualified. But I can assess an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point.
Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess their work, check their assumptions, present cogent opposing arguments. There is some thought that a dish antenna properly implemented will overcome the obstacles described by the design team. Let's model this. Or those who live in heavy 802.11b environments, do some experiements with terrestrial links (which I suppose could be assumed worse than earth/sky). Who knows? Maybe it's all like my last tax return, where a missed decimal point made me think I'd have to take out a second mortgage to pay our taxes :-) This list and the wiki exist so that we can undertake that sort of dialogue, and for my part, it is my favorite part of participation in AMSAT.
Some have suggested that Eagle fly with an S-band downlink on the off chance that it *does* work despite the theory; others, that we survey the members to see what they'd like. I fully support the design teams rejection of the former approach. Launch weight is very expensive and the kitchen sink approach is not to my mind sensible. As to the latter, a survey presumably pertains only to *working* bands, not ones that are polluted out of existance.
It's human nature for us more readily to see our misfortunes as caused by the malace of others, but I think we should strongly avoid terms like "bait and switch". We'll get much further if we all assume the goodwill of everyone involved.
73, Bruce VE9QRP _______________________________________________ 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
O.K. S or no S we are 5 years to launch. Forcasting band conditions and QRM at that point in time is 95 % dark clouds and 5% reality! getting satellite anything, built, tested, launched, and operational is not an easy task, certainly fnot for the faint of heart! If we do not decide now what we use we will not have anything at launch time even with 10,000 sidewalk engineers on the job!. . The 10 GHz band is the only band that does not provide for part 15 ISM equipment. 2.4 and 5.8 are good places to transmit. Pyro Joe has had some good deals on 30 + watt 2.4 GHz amps @ reasonable prices. I use one on ATV 18 MHz wide FM, not a lot of 2.4 activity here! Hmm. Maybe we should all be on ATV until P3E is operational.
Art, KC6UQH ----- Original Message ----- From: "Joe Westbrook" k7zt@cox.net To: brobertson@mta.ca; amsat-bb@amsat.org Sent: Thursday, September 07, 2006 6:01 PM Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higher leveldiscussion
Bruce: Are you suggesting that "Please,, those of you who are qualified and competent" are the only folks who are worthy of a dissenting view regarding this topic? Please, that is precisely the attitude that turn folks off of AMSAT-NA, that elitist attitude has no place in a HOBBY. Particularly when we ALL contribute to the construction of the satellites. It just happens that I am a professional Network Engineer (Trainer) for a Telecommunications Company.
My background spans virtually every communications technology from DC to Daylight. I have an extensive background in EMI/RFI Labatory Testing, culminating in 35+ non-stop years in the Communications field. No I don't have any matamatical studies, what I do have is first hand empirical experience in a neighborhood where EVERY Home has at least a single 2.4GHz radiation source .
I worked AO-40 and thoroughly enjoyed the S Band downlink and have maintained the station in anticipation of continuing this activity on the HEOs. I'm not alone, I'm sure that the majority of members who have made the S Band and Investment.
Do I get interference from the IEEE 802.X devices and portable phones, yes, in the form of random clicks that are easily removed by using a noise blanker, try it works great!
What, if any studies considered that 5.2Ghz devices are taking off now and will probably eclipse the 2.4Gig interference levels. Make any argument you wish for dropping S Band from Eagle, but don't use the polluted spectrum argument, it simply doesn't hold water.
Regards, Joe, K7ZT
----- Original Message ----- From: "Bruce Robertson" broberts@mta.ca To: amsat-bb@amsat.org Sent: Thursday, September 07, 2006 5:06 Subject: [amsat-bb] S band and Eagle: an appeal for a higher level discussion
There has been a recent restatement of disappointment regarding the Eagle design committee's recent choice to use S band as an uplink not a downlink. Note that the next two HEO's scheduled to launch *will* have S band downlinks, so there's no worry that people like I, who live in radio quiet areas, will be unable to use our developing S band equipment in the future.
As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.
The design team have said again and again on this list that they would welcome contradicting evidence that is cogent, and I, for one, believe them. They're our volunteers, and they deserve our support. I can't provide that contradicting evidence: I'm not skilled or qualified. But I can assess an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point.
Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess their work, check their assumptions, present cogent opposing arguments. There is some thought that a dish antenna properly implemented will overcome the obstacles described by the design team. Let's model this. Or those who live in heavy 802.11b environments, do some experiements with terrestrial links (which I suppose could be assumed worse than earth/sky). Who knows? Maybe it's all like my last tax return, where a missed decimal point made me think I'd have to take out a second mortgage to pay our taxes :-) This list and the wiki exist so that we can undertake that sort of dialogue, and for my part, it is my favorite part of participation in AMSAT.
Some have suggested that Eagle fly with an S-band downlink on the off chance that it *does* work despite the theory; others, that we survey the members to see what they'd like. I fully support the design teams rejection of the former approach. Launch weight is very expensive and the kitchen sink approach is not to my mind sensible. As to the latter, a survey presumably pertains only to *working* bands, not ones that are polluted out of existance.
It's human nature for us more readily to see our misfortunes as caused by the malace of others, but I think we should strongly avoid terms like "bait and switch". We'll get much further if we all assume the goodwill of everyone involved.
73, Bruce VE9QRP _______________________________________________ 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
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
--- kc6uqh kc6uqh@cox.net wrote:
The 10 GHz band is the only band that does not provide for part 15 ISM equipment.
True but bear in mind that in some contries only 10.450 - 10.460 GHz is available for Amateur Satellite use.
2.4 and 5.8 are good places to transmit.
Except that in a number of countries Amateurs have been banned from transmitting in 2.40 - 2.45 GHz in order to protect the myriad of unlicenced consumer devices operating in that band. 2.40 - 2.45 GHz is a bad place for an uplink.
At the present time a transponder downlink operating near the bottom edge of the Satellite allocation, somewhere between 2.400 and 2.401, is viable. The big question is what will it be like during the operational lifetime of the two Eagles from 2011 to 2026 ?
More and more consumer devices are having WiFi/Bluetooth added to them. It is not unrealistic to expect that by 2012 most households will have 3 or 4 seperate 2.4 GHz devices running continuously. In urban areas this would create significant problems for satellite operation.
Long term we need additional S-Band spectrum for the Amateur Satellite Service, say 2.390 - 2.400 GHz and/or 2.300 - 2.310 GHz although the latter allocation may be problematic with some countries.
We can only get additional Satellite allocations through the ITU. Is the ARRL considering putting forward any proposals regarding this ?
New allocations would of course take several years to acheive.
73 Trevor M5AKA
___________________________________________________________ Now you can scan emails quickly with a reading pane. Get the new Yahoo! Mail. http://uk.docs.yahoo.com/nowyoucan.html
Quoting Joe Westbrook k7zt@cox.net:
Bruce: Are you suggesting that "Please,, those of you who are qualified and competent" are the only folks who are worthy of a dissenting view regarding this topic? Please, that is precisely the attitude that turn folks off of AMSAT-NA, that elitist attitude has no place in a HOBBY. Particularly when we ALL contribute to the construction of the satellites. It just happens that I am a professional Network Engineer (Trainer) for a Telecommunications Company.
Sorry if I seemed rude. I had meant the description of people who are qualified and competent to contrast with myself, whom I described before that quotation as "not skilled or qualified". And this is a statement I will stand by firmly :-)
Nor did I mean to suggest that people so defined are the only ones whose opinions matter. After all, I offered my opinion! I just know that some of the people who were writing, like yourself, have more of a means to analyze things, do some math, consult industry predictions, etc. And I'd like you (pl.) to prove wrong the contention that S band will be a sewer in X years. Let's all dispassionately read the article in the Journal, the material in Eaglepedia and see if we can find problems with it.
For instance, you argue that 5 GHz will be just as 'polluted' as 2.4 in the near future. I'd consider it a personal favour, and I'm sure many others would, if you were to cite what you consider authoritative studies to that effect.
One way or another, with the kind help of the people on this list and excellent on-air advice, I'm slowly building up my S band station and looking forward to my first HEO contacts on P3E.
73, Bruce VE9QRP
On 7 Sep 2006 at 19:06, Bruce Robertson wrote:
As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications.
I probably missed something here! Can you guide us where we can read what make's you "understand it" Why all the new Wi-FI device in all the electronic/computer stores around us here in QC are actually migrating towards 5.2ghz and higher? I was in Miami FL in July and i observed the same trend?
But I can assess an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point.
Have you been on AO-51 last week where U/S mode was on? I was and i can tell you there is absolutely no interference who prevent me to hear and make contacts without any problem..That's what i called rigorous testing... Use it test it and speak about what you know not on what you hear about. I am not trying to second guessing anyone here!
Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess their work, check their assumptions, present cogent opposing arguments.
Again show us where you read/hear "the design committee words" as rigorous you approach seems to be here is the way to prove it to us. I am not the one who blindly believe, and even more when we speak about AMSAT-NA...
"-" The medium is the message...The content is the audience...;)
Luc Leblanc VE2DWE Skype VE2DWE www.qsl.net/ve2dwe
{Tilt}
If 2.4 ghz pollution is going to be a problem for stations on the ground who are looking up (and away from) the noise, how is it possible that a satellite in the sky looking down on half of a planet's worth of 2.4 ghz noise, is going to be able to pick out one earthly station over the din? This is totally backwards in my mind.
Please, mode VS or US makes sense for the "installed base". Mode B suffers from a worse problem than the S-band noise: physics. The Mode B receive antennas need to be phyiscally large, and putting up large antennas is becomming a problem more rapidly than overcoming noise on 2.4. Small lots, CC&Rs, and other "environmental" factors are forcing hams to make do with smaller, less obtrusive antennas. I can solve the small antenna uplink problem on V with a power amp; I cannot solve the problem of a small antenna downlink problem on V, even with a preamp. I tried that when AO-13 was still up, and managed to get *one* contact. Really, I should be running LS. That would force me to get on 1.2 ghz.
Plus, noise on V is also getting worse by the day. For years I have checked into a weekly SSB net on 2m (144.250 8pm local on Sundays) and have noticed there has been a huge increase in noise coming from the populated areas. Like Bill, I live in the Sierra Foothills (Auburn for me), and overlook the Sacramento Valley. The noise peak from the direction of Stockton & Sacramento is amazing. 2.4 may be getting worse, but 2m noise is getting worse faster, and at least the laws of physics allow us to create S-band receive systems that can aim around (over) the din.
Greg KO6TH
----Original Message Follows---- From: Bruce Robertson broberts@mta.ca Reply-To: brobertson@mta.ca To: amsat-bb@amsat.org Subject: [amsat-bb] S band and Eagle: an appeal for a higher level discussion Date: Thu, 7 Sep 2006 19:06:17 -0300
There has been a recent restatement of disappointment regarding the Eagle design committee's recent choice to use S band as an uplink not a downlink. Note that the next two HEO's scheduled to launch *will* have S band downlinks, so there's no worry that people like I, who live in radio quiet areas, will be unable to use our developing S band equipment in the future.
As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.
The design team have said again and again on this list that they would welcome contradicting evidence that is cogent, and I, for one, believe them. They're our volunteers, and they deserve our support. I can't provide that contradicting evidence: I'm not skilled or qualified. But I can assess an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point.
Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess their work, check their assumptions, present cogent opposing arguments. There is some thought that a dish antenna properly implemented will overcome the obstacles described by the design team. Let's model this. Or those who live in heavy 802.11b environments, do some experiements with terrestrial links (which I suppose could be assumed worse than earth/sky). Who knows? Maybe it's all like my last tax return, where a missed decimal point made me think I'd have to take out a second mortgage to pay our taxes :-) This list and the wiki exist so that we can undertake that sort of dialogue, and for my part, it is my favorite part of participation in AMSAT.
Some have suggested that Eagle fly with an S-band downlink on the off chance that it *does* work despite the theory; others, that we survey the members to see what they'd like. I fully support the design teams rejection of the former approach. Launch weight is very expensive and the kitchen sink approach is not to my mind sensible. As to the latter, a survey presumably pertains only to *working* bands, not ones that are polluted out of existance.
It's human nature for us more readily to see our misfortunes as caused by the malace of others, but I think we should strongly avoid terms like "bait and switch". We'll get much further if we all assume the goodwill of everyone involved.
73, Bruce VE9QRP _______________________________________________ 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
----- Original Message ----- From: "Greg D." ko6th_greg@hotmail.com To: amsat-bb@amsat.org Sent: Sunday, September 10, 2006 8:40 PM Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higher leveldiscussion
If 2.4 ghz pollution is going to be a problem for stations on the ground
who
are looking up (and away from) the noise, how is it possible that a satellite in the sky looking down on half of a planet's worth of 2.4 ghz noise, is going to be able to pick out one earthly station over the din? This is totally backwards in my mind.
Greg KO6TH
Hi Greg, KO6TH
It is possible !
During the test of 23 Feb 2003 AO40 was looking down on half of the planet's using his S1 high-gain dish connected to the S1 RX worth of noise on 2400.475 MHz and was able to pick out G3WDG and i8CVS for the first experiment on S/K band in wich an amateur satellite was succesfully tested the first time to receive over the dim an uplink at 2400.475 MHz
So it is totally backward in my mind why the S band is considered a sewer three years now from the above test.
If you look at the following page you have the complete report written by G3WDG and a wave-file showing how clean where both signals over the noise on SSB
http://www.g3wdg.free-online.co.uk/s_ktest.htm
----------------------------------------------------------------------------
Quoting Stacey E. Mills W3SM [amsat-bb] AO-40 Update, 2003-02-23
Two tests were performed on AO-40 today.
The second test involving the S-band receivers was completely successful. Extremely strong downlink signals were possible using S-band uplink to K-band downlink. Charlie (G3WDG) phoned me and I heard beautiful downlink signals from his ~5 watt uplink to S1. S2 was also active, but because of its higher, less common frequency (2446 MHz), it may not have been tested. The S1 Rx uses the S1 Tx high-gain dish, and the S2 Rx uses the 5 turn helix used by the S2 Tx, so signals would not be as strong through S2 at low squint. More information will undoubtedly be posted on this by the participants, but special thanks to Charlie (G3WDG), Mike (N1JEZ), and Dom (I8CVS), and any others who participated in this successful test.
The S1 Rx can certainly be listed as fully functional. We will await further testing/info. on the S2 Rx.
--W4SM for the AO-40 Command Team ----------------------------------------------------------------------------
Quoting Charlie G3WDG [amsat-bb] AO-40 S/K Test
All,
I have posted some info on the tests here, including some recordings of G3WDG and I8CVS's S-Band signals received on K-Band.
http://www.g3wdg.free-online.co.uk/s_ktest.htm
73
Charlie G3WDG ----------------------------------------------------------------------------
Best 73" de
i8CVS Domenico
For 13 cm uplinks we can just overpower the interferers. The WiFi interference is attenuated at the same rate as the uplink signal. Most interferers are 10 mW EIRP or less and the uplink is 1 KW EIRP or more.
For a 13 cm downlink, increasing the power level is impractical as solar panels are very expensive.
73,
John KD6OZH
----- Original Message ----- From: "i8cvs" domenico.i8cvs@tin.it To: "Greg D." ko6th_greg@hotmail.com; "AMSAT-BB" amsat-bb@amsat.org Sent: Monday, September 11, 2006 02:11 UTC Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higherleveldiscussion
----- Original Message ----- From: "Greg D." ko6th_greg@hotmail.com To: amsat-bb@amsat.org Sent: Sunday, September 10, 2006 8:40 PM Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higher leveldiscussion
If 2.4 ghz pollution is going to be a problem for stations on the ground
who
are looking up (and away from) the noise, how is it possible that a satellite in the sky looking down on half of a planet's worth of 2.4 ghz noise, is going to be able to pick out one earthly station over the din? This is totally backwards in my mind.
Greg KO6TH
Hi Greg, KO6TH
It is possible !
During the test of 23 Feb 2003 AO40 was looking down on half of the planet's using his S1 high-gain dish connected to the S1 RX worth of noise on 2400.475 MHz and was able to pick out G3WDG and i8CVS for the first experiment on S/K band in wich an amateur satellite was succesfully tested the first time to receive over the dim an uplink at 2400.475 MHz
So it is totally backward in my mind why the S band is considered a sewer three years now from the above test.
If you look at the following page you have the complete report written by G3WDG and a wave-file showing how clean where both signals over the noise on SSB
http://www.g3wdg.free-online.co.uk/s_ktest.htm
--
Quoting Stacey E. Mills W3SM [amsat-bb] AO-40 Update, 2003-02-23
Two tests were performed on AO-40 today.
The second test involving the S-band receivers was completely successful. Extremely strong downlink signals were possible using S-band uplink to K-band downlink. Charlie (G3WDG) phoned me and I heard beautiful downlink signals from his ~5 watt uplink to S1. S2 was also active, but because of its higher, less common frequency (2446 MHz), it
may
not have been tested. The S1 Rx uses the S1 Tx high-gain dish, and the S2 Rx uses the 5 turn helix used by the S2 Tx, so signals would not be as strong through S2 at low squint. More information will undoubtedly be posted on this by the participants, but special thanks to Charlie (G3WDG), Mike (N1JEZ), and Dom (I8CVS), and any others who participated in this successful test.
The S1 Rx can certainly be listed as fully functional. We will await further testing/info. on the S2 Rx.
--W4SM for the AO-40 Command Team
--
Quoting Charlie G3WDG [amsat-bb] AO-40 S/K Test
All,
I have posted some info on the tests here, including some recordings of G3WDG and I8CVS's S-Band signals received on K-Band.
http://www.g3wdg.free-online.co.uk/s_ktest.htm
73
Charlie G3WDG
--
Best 73" de
i8CVS Domenico
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
Hi John,
My concern on the uplink side is that any individual interferer is low power but there will be many tens of thousands of them wihin the field of view of the satellite. If there are enough of them on the ground to be a problem in the immediate vicinity of a station, then surely they would be a problem for the satellite looking down. I agree that we can probably scream louder than the collective noise, but how we get the signal to scream that loud is another question. Someone pointed out that power amps are going to be cheap because of all the WiFi gear out there, and that's probably true, but we're not going to get to a kw EIRP from one without a pretty big antenna (1W to 1KW is 30 db, right?). And, there aren't any up-converters coming free like we had with the MMDS downconverters that we all found. We have ready access to equipment and power on 2m and 70cm, making U and V uplinks easy and wide spread.
On the downlink side, my own opinion is that there will be a natural saturation point of 2.4 ghz equipment that is below the projections. One of the reasons I have for this opinion is that self-interference and marketing will drive many to 5 ghz (we see cordless phones already packing up and headed there now), and the demands on WiFi will force the move to 5 ghz for its non-overlaping channels. 802.11a is already there, and 802.11n is coming (pre-n stuff is on 2.4, but the standard also covers 5 ghz). One cranked-up 802.11n channel covers 40 mhz, which pretty much wipes out half of the 2.4 ghz allocation, so it's not going to live long down there.
The other factor is that there is a limit to how many gizmos we will put up with. The manufacturers have this happy stockholder-driven picture of everyone wandering around with a thingy sticking out of their ear, bluetoothed to a thingy on their belt, which talks to another thingy on their belt, in their pocket, on their wrist, the car naviation system, the home entertainment system, keyboard, mouse, coffee maker, and so on, ad nausium (with emphasis on the nausium part). My prediction is that there will be a revolt at some point, with too many gadgets being thrown at us, and people will buy ONE device that has a bunch of these things all built in (without the many wireless links). Either that, or our attention deficient society will tire of this line of business, and the rest of the gadgets will sit turned off in the drawer, on the shelf, or in the land fill, awaiting the day when some future archaeologist digs them up and wonders what on Earth we were thinking. The area networks, replacing the ill-fated BPL systems, will be on licensed spectrum, because (as my own internet service provider is finding out) unlicensed spectrum is too crowded to build a business around. All of this adds up to much less 2.4 ghz interference.
Just my own opinion,
Greg KO6TH
----Original Message Follows---- From: "John B. Stephensen" kd6ozh@comcast.net To: "i8cvs" domenico.i8cvs@tin.it,"Greg D." ko6th_greg@hotmail.com,"AMSAT-BB" amsat-bb@amsat.org Subject: Re: [amsat-bb] Re: S band and Eagle: an appeal for a higherleveldiscussion Date: Mon, 11 Sep 2006 03:20:05 -0000
For 13 cm uplinks we can just overpower the interferers. The WiFi interference is attenuated at the same rate as the uplink signal. Most interferers are 10 mW EIRP or less and the uplink is 1 KW EIRP or more.
For a 13 cm downlink, increasing the power level is impractical as solar panels are very expensive.
73,
John KD6OZH
----- Original Message ----- From: "i8cvs" domenico.i8cvs@tin.it To: "Greg D." ko6th_greg@hotmail.com; "AMSAT-BB" amsat-bb@amsat.org Sent: Monday, September 11, 2006 02:11 UTC Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higherleveldiscussion
----- Original Message ----- From: "Greg D." ko6th_greg@hotmail.com To: amsat-bb@amsat.org Sent: Sunday, September 10, 2006 8:40 PM Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higher leveldiscussion
If 2.4 ghz pollution is going to be a problem for stations on the
ground
who
are looking up (and away from) the noise, how is it possible that a satellite in the sky looking down on half of a planet's worth of 2.4
ghz
noise, is going to be able to pick out one earthly station over the
din?
This is totally backwards in my mind.
Greg KO6TH
Hi Greg, KO6TH
It is possible !
During the test of 23 Feb 2003 AO40 was looking down on half of the planet's using his S1 high-gain dish connected to the S1 RX worth of noise on 2400.475 MHz and was able to pick out G3WDG and i8CVS for the first experiment on S/K band in wich an amateur satellite was succesfully tested the first time to receive over the dim an uplink at 2400.475 MHz
So it is totally backward in my mind why the S band is considered a sewer three years now from the above test.
If you look at the following page you have the complete report written by G3WDG and a wave-file showing how clean where both signals over the noise on SSB
-------------------------------------------------------------------------- --
Quoting Stacey E. Mills W3SM [amsat-bb] AO-40 Update, 2003-02-23
Two tests were performed on AO-40 today.
The second test involving the S-band receivers was completely successful. Extremely strong downlink signals were possible using S-band uplink to K-band downlink. Charlie (G3WDG) phoned me and I heard beautiful downlink signals from his ~5 watt uplink to S1. S2 was also active, but because of its higher, less common frequency (2446 MHz), it
may
not have been tested. The S1 Rx uses the S1 Tx high-gain dish, and the
S2
Rx uses the 5 turn helix used by the S2 Tx, so signals would not be as strong through S2 at low squint. More information will undoubtedly be posted on this by the participants, but special thanks to Charlie
(G3WDG),
Mike (N1JEZ), and Dom (I8CVS), and any others who participated in this successful test.
The S1 Rx can certainly be listed as fully functional. We will await further testing/info. on the S2 Rx.
--W4SM for the AO-40 Command Team
-------------------------------------------------------------------------- --
Quoting Charlie G3WDG [amsat-bb] AO-40 S/K Test
All,
I have posted some info on the tests here, including some recordings of G3WDG and I8CVS's S-Band signals received on K-Band.
http://www.g3wdg.free-online.co.uk/s_ktest.htm
73
Charlie G3WDG
-------------------------------------------------------------------------- --
Best 73" de
i8CVS Domenico
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
A calculation was made estimating the worst-case contribution of 802.11 equipment in the footprint and it raised the noise floor at the satellite, but not by much. At S-band, a 2-foot dish gives 26 dBic of gain and with 4 parallel 1 W amplifier ICs ($5 each) this provides 1600 W EIRP. We'd like to allow use of WiFi parts as most mcrowave power transistors cost over $100 each.
I originally argued for an L-band digital uplink but was persuaded that it's too risky.
73,
John KD6OZH
----- Original Message ----- From: "Greg D." ko6th_greg@hotmail.com To: kd6ozh@comcast.net; domenico.i8cvs@tin.it; amsat-bb@amsat.org Sent: Monday, September 11, 2006 05:58 UTC Subject: Re: [amsat-bb] Re: S band and Eagle: an appeal for a higherleveldiscussion
Hi John,
My concern on the uplink side is that any individual interferer is low
power
but there will be many tens of thousands of them wihin the field of view
of
the satellite. If there are enough of them on the ground to be a problem
in
the immediate vicinity of a station, then surely they would be a problem
for
the satellite looking down. I agree that we can probably scream louder
than
the collective noise, but how we get the signal to scream that loud is another question. Someone pointed out that power amps are going to be
cheap
because of all the WiFi gear out there, and that's probably true, but
we're
not going to get to a kw EIRP from one without a pretty big antenna (1W to 1KW is 30 db, right?). And, there aren't any up-converters coming free
like
we had with the MMDS downconverters that we all found. We have ready
access
to equipment and power on 2m and 70cm, making U and V uplinks easy and
wide
spread.
On the downlink side, my own opinion is that there will be a natural saturation point of 2.4 ghz equipment that is below the projections. One
of
the reasons I have for this opinion is that self-interference and
marketing
will drive many to 5 ghz (we see cordless phones already packing up and headed there now), and the demands on WiFi will force the move to 5 ghz
for
its non-overlaping channels. 802.11a is already there, and 802.11n is coming (pre-n stuff is on 2.4, but the standard also covers 5 ghz). One cranked-up 802.11n channel covers 40 mhz, which pretty much wipes out half of the 2.4 ghz allocation, so it's not going to live long down there.
The other factor is that there is a limit to how many gizmos we will put
up
with. The manufacturers have this happy stockholder-driven picture of everyone wandering around with a thingy sticking out of their ear, bluetoothed to a thingy on their belt, which talks to another thingy on their belt, in their pocket, on their wrist, the car naviation system, the home entertainment system, keyboard, mouse, coffee maker, and so on, ad nausium (with emphasis on the nausium part). My prediction is that there will be a revolt at some point, with too many gadgets being thrown at us, and people will buy ONE device that has a bunch of these things all built
in
(without the many wireless links). Either that, or our attention
deficient
society will tire of this line of business, and the rest of the gadgets
will
sit turned off in the drawer, on the shelf, or in the land fill, awaiting the day when some future archaeologist digs them up and wonders what on Earth we were thinking. The area networks, replacing the ill-fated BPL systems, will be on licensed spectrum, because (as my own internet service provider is finding out) unlicensed spectrum is too crowded to build a business around. All of this adds up to much less 2.4 ghz interference.
Just my own opinion,
Greg KO6TH
----Original Message Follows---- From: "John B. Stephensen" kd6ozh@comcast.net To: "i8cvs" domenico.i8cvs@tin.it,"Greg D." ko6th_greg@hotmail.com,"AMSAT-BB" amsat-bb@amsat.org Subject: Re: [amsat-bb] Re: S band and Eagle: an appeal for a higherleveldiscussion Date: Mon, 11 Sep 2006 03:20:05 -0000
For 13 cm uplinks we can just overpower the interferers. The WiFi interference is attenuated at the same rate as the uplink signal. Most interferers are 10 mW EIRP or less and the uplink is 1 KW EIRP or more.
For a 13 cm downlink, increasing the power level is impractical as solar panels are very expensive.
73,
John KD6OZH
----- Original Message ----- From: "i8cvs" domenico.i8cvs@tin.it To: "Greg D." ko6th_greg@hotmail.com; "AMSAT-BB" amsat-bb@amsat.org Sent: Monday, September 11, 2006 02:11 UTC Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higherleveldiscussion
----- Original Message ----- From: "Greg D." ko6th_greg@hotmail.com To: amsat-bb@amsat.org Sent: Sunday, September 10, 2006 8:40 PM Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higher leveldiscussion
If 2.4 ghz pollution is going to be a problem for stations on the
ground
who
are looking up (and away from) the noise, how is it possible that a satellite in the sky looking down on half of a planet's worth of 2.4
ghz
noise, is going to be able to pick out one earthly station over the
din?
This is totally backwards in my mind.
Greg KO6TH
Hi Greg, KO6TH
It is possible !
During the test of 23 Feb 2003 AO40 was looking down on half of the planet's using his S1 high-gain dish connected to the S1 RX worth of noise on 2400.475 MHz and was able to pick out G3WDG and i8CVS for the first experiment on S/K band in wich an amateur satellite was succesfully tested the first time to receive over the dim an uplink at 2400.475 MHz
So it is totally backward in my mind why the S band is considered a
sewer
three years now from the above test.
If you look at the following page you have the complete report written
by
G3WDG and a wave-file showing how clean where both signals over the noise on SSB
--
Quoting Stacey E. Mills W3SM [amsat-bb] AO-40 Update, 2003-02-23
Two tests were performed on AO-40 today.
The second test involving the S-band receivers was completely successful. Extremely strong downlink signals were possible using
S-band
uplink to K-band downlink. Charlie (G3WDG) phoned me and I heard beautiful downlink signals from his ~5 watt uplink to S1. S2 was also active, but because of its higher, less common frequency (2446 MHz), it
may
not have been tested. The S1 Rx uses the S1 Tx high-gain dish, and the
S2
Rx uses the 5 turn helix used by the S2 Tx, so signals would not be as strong through S2 at low squint. More information will undoubtedly be posted on this by the participants, but special thanks to Charlie
(G3WDG),
Mike (N1JEZ), and Dom (I8CVS), and any others who participated in this successful test.
The S1 Rx can certainly be listed as fully functional. We will await further testing/info. on the S2 Rx.
--W4SM for the AO-40 Command Team
--
Quoting Charlie G3WDG [amsat-bb] AO-40 S/K Test
All,
I have posted some info on the tests here, including some recordings of G3WDG and I8CVS's S-Band signals received on K-Band.
http://www.g3wdg.free-online.co.uk/s_ktest.htm
73
Charlie G3WDG
--
Best 73" de
i8CVS Domenico
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
It is a simple matter for a ground station to raise power and be heard above the din. Most WiFi are at the milliWatt level. It is hard for the satellite to raise power and be heard above the din.
I found AO-13 to be the opposite. My original mode B (V) antenna was not large, and was not near the wind load or weight of my small dish. Later I went to a larger Yagi, because I got "into" the ZRO tests.
A little simple math from the ZRO test.
Let's assume the downlink from the new bird will as good as AO-13 (I expect it will be better). With a 12 foot yagi I made ZRO 9 which is 27dB below the recommended signal level for QSOs. I will confess it was tough copy so I will give up another 3 dB just to be nice. So my 12 foot yagi (homebrew, not computer optimized) had 24 dB to spare. A six foot Yagi should have 21 dB to spare. A three foot Yagi should have 18 dB to spare.
We are not talking about large antennas. The Yagi does need proper care and feeding, but I never did smoke it by transmitting into it either.
Looking forward to mode B (U/V) again, 73, Joe
----- Original Message ----- From: "Greg D." ko6th_greg@hotmail.com To: amsat-bb@amsat.org Sent: Sunday, September 10, 2006 1:40 PM Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higher leveldiscussion
{Tilt}
If 2.4 ghz pollution is going to be a problem for stations on the ground who are looking up (and away from) the noise, how is it possible that a satellite in the sky looking down on half of a planet's worth of 2.4 ghz noise, is going to be able to pick out one earthly station over the din? This is totally backwards in my mind.
Please, mode VS or US makes sense for the "installed base". Mode B suffers from a worse problem than the S-band noise: physics. The Mode B receive antennas need to be phyiscally large, and putting up large antennas is becomming a problem more rapidly than overcoming noise on 2.4. Small lots, CC&Rs, and other "environmental" factors are forcing hams to make do with smaller, less obtrusive antennas. I can solve the small antenna uplink problem on V with a power amp; I cannot solve the problem of a small antenna downlink problem on V, even with a preamp. I tried that when AO-13 was still up, and managed to get *one* contact. Really, I should be running LS. That would force me to get on 1.2 ghz.
Plus, noise on V is also getting worse by the day. For years I have checked into a weekly SSB net on 2m (144.250 8pm local on Sundays) and have noticed there has been a huge increase in noise coming from the populated areas. Like Bill, I live in the Sierra Foothills (Auburn for me), and overlook the Sacramento Valley. The noise peak from the direction of Stockton & Sacramento is amazing. 2.4 may be getting worse, but 2m noise is getting worse faster, and at least the laws of physics allow us to create S-band receive systems that can aim around (over) the din.
Greg KO6TH
----Original Message Follows---- From: Bruce Robertson broberts@mta.ca Reply-To: brobertson@mta.ca To: amsat-bb@amsat.org Subject: [amsat-bb] S band and Eagle: an appeal for a higher level discussion Date: Thu, 7 Sep 2006 19:06:17 -0300
There has been a recent restatement of disappointment regarding the Eagle design committee's recent choice to use S band as an uplink not a downlink. Note that the next two HEO's scheduled to launch *will* have S band downlinks, so there's no worry that people like I, who live in radio quiet areas, will be unable to use our developing S band equipment in the future.
As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.
The design team have said again and again on this list that they would welcome contradicting evidence that is cogent, and I, for one, believe them. They're our volunteers, and they deserve our support. I can't provide that contradicting evidence: I'm not skilled or qualified. But I can assess an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point.
Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess their work, check their assumptions, present cogent opposing arguments. There is some thought that a dish antenna properly implemented will overcome the obstacles described by the design team. Let's model this. Or those who live in heavy 802.11b environments, do some experiements with terrestrial links (which I suppose could be assumed worse than earth/sky). Who knows? Maybe it's all like my last tax return, where a missed decimal point made me think I'd have to take out a second mortgage to pay our taxes :-) This list and the wiki exist so that we can undertake that sort of dialogue, and for my part, it is my favorite part of participation in AMSAT.
Some have suggested that Eagle fly with an S-band downlink on the off chance that it *does* work despite the theory; others, that we survey the members to see what they'd like. I fully support the design teams rejection of the former approach. Launch weight is very expensive and the kitchen sink approach is not to my mind sensible. As to the latter, a survey presumably pertains only to *working* bands, not ones that are polluted out of existance.
It's human nature for us more readily to see our misfortunes as caused by the malace of others, but I think we should strongly avoid terms like "bait and switch". We'll get much further if we all assume the goodwill of everyone involved.
73, Bruce VE9QRP _______________________________________________ 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
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
Hmmpf. Wonder what I was doing wrong? I had a 5 element yagi at the time, upgraded to an 8, and still hardly heard anything out of the bird. The one contact I had was when the satellite was only a few thousand km up. The 8' boom on the 2m antenna is the longest my roof tripod will take. Part of the problem probably was the 60' of RG-213 to the Shack. I now have some old hardline in its place, but that came after it was too late. Perhaps I'll get another chance with the new birds...
I handle the "smoke" problem by using an ICOM R-7000 receiver for the S-band IF. Deaf, but it also doesn't transmit.
Greg KO6TH
----Original Message Follows---- From: "Gary "Joe" Mayfield" gary_mayfield@hotmail.com To: amsat-bb@amsat.org Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higherleveldiscussion Date: Sun, 10 Sep 2006 23:13:44 -0500
It is a simple matter for a ground station to raise power and be heard above the din. Most WiFi are at the milliWatt level. It is hard for the satellite to raise power and be heard above the din.
I found AO-13 to be the opposite. My original mode B (V) antenna was not large, and was not near the wind load or weight of my small dish. Later I went to a larger Yagi, because I got "into" the ZRO tests.
A little simple math from the ZRO test.
Let's assume the downlink from the new bird will as good as AO-13 (I expect it will be better). With a 12 foot yagi I made ZRO 9 which is 27dB below the recommended signal level for QSOs. I will confess it was tough copy so I will give up another 3 dB just to be nice. So my 12 foot yagi (homebrew, not computer optimized) had 24 dB to spare. A six foot Yagi should have 21 dB to spare. A three foot Yagi should have 18 dB to spare.
We are not talking about large antennas. The Yagi does need proper care and feeding, but I never did smoke it by transmitting into it either.
Looking forward to mode B (U/V) again, 73, Joe
----- Original Message ----- From: "Greg D." ko6th_greg@hotmail.com To: amsat-bb@amsat.org Sent: Sunday, September 10, 2006 1:40 PM Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higher leveldiscussion
{Tilt}
If 2.4 ghz pollution is going to be a problem for stations on the ground who are looking up (and away from) the noise, how is it possible that a satellite in the sky looking down on half of a planet's worth of 2.4 ghz noise, is going to be able to pick out one earthly station over the din? This is totally backwards in my mind.
Please, mode VS or US makes sense for the "installed base". Mode B suffers from a worse problem than the S-band noise: physics. The Mode B receive antennas need to be phyiscally large, and putting up large antennas is becomming a problem more rapidly than overcoming noise on 2.4. Small lots, CC&Rs, and other "environmental" factors are forcing hams to make do with smaller, less obtrusive antennas. I can solve the small antenna uplink problem on V with a power amp; I cannot solve the problem of a small antenna downlink problem on V, even with a preamp. I tried that when AO-13 was still up, and managed to get *one* contact. Really, I should be running LS. That would force me to get on 1.2 ghz.
Plus, noise on V is also getting worse by the day. For years I have checked into a weekly SSB net on 2m (144.250 8pm local on Sundays) and have noticed there has been a huge increase in noise coming from the populated areas. Like Bill, I live in the Sierra Foothills (Auburn for me), and overlook the Sacramento Valley. The noise peak from the direction of Stockton & Sacramento is amazing. 2.4 may be getting worse, but 2m noise is getting worse faster, and at least the laws of physics allow us to create S-band receive systems that can aim around (over) the din.
Greg KO6TH
----Original Message Follows---- From: Bruce Robertson broberts@mta.ca Reply-To: brobertson@mta.ca To: amsat-bb@amsat.org Subject: [amsat-bb] S band and Eagle: an appeal for a higher level discussion Date: Thu, 7 Sep 2006 19:06:17 -0300
There has been a recent restatement of disappointment regarding the Eagle design committee's recent choice to use S band as an uplink not a downlink. Note that the next two HEO's scheduled to launch *will* have S band downlinks, so there's no worry that people like I, who live in radio
quiet
areas, will be unable to use our developing S band equipment in the future.
As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.
The design team have said again and again on this list that they would welcome contradicting evidence that is cogent, and I, for one, believe them. They're our volunteers, and they deserve our support. I can't provide that contradicting evidence: I'm not skilled or qualified. But I can assess an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point.
Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess
their
work, check their assumptions, present cogent opposing arguments. There
is
some thought that a dish antenna properly implemented will overcome the obstacles described by the design team. Let's model this. Or those who live in heavy 802.11b environments, do some experiements with terrestrial
links
(which I suppose could be assumed worse than earth/sky). Who knows? Maybe it's all like my last tax return, where a missed decimal point made me think I'd have to take out a second mortgage to pay our taxes :-) This list and the wiki exist so that we can undertake that sort of dialogue, and
for
my part, it is my favorite part of participation in AMSAT.
Some have suggested that Eagle fly with an S-band downlink on the off chance that it *does* work despite the theory; others, that we survey the members to see what they'd like. I fully support the design teams rejection of the former approach. Launch weight is very expensive and the kitchen sink approach is not to my mind sensible. As to the latter, a survey presumably pertains only to *working* bands, not ones that are polluted out of existance.
It's human nature for us more readily to see our misfortunes as caused by the malace of others, but I think we should strongly avoid terms like "bait and switch". We'll get much further if we all assume the goodwill of everyone involved.
73, Bruce VE9QRP _______________________________________________ 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
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
_______________________________________________ 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
Mode B suffers from a worse problem than the S-band noise: physics. The Mode B receive antennas need to be phyiscally large, and putting up large antennas is becomming a problem more rapidly than overcoming noise on 2.4.
Lets preserve 2m downlinks for OMNI directional downlinks to Mobiles and handhelds where the 19" mobile whip OMNI has a 9 dB advantage over 70cm and a 24 dB advantage over 2.4 GHz.
We can easily close the link to mobiles and handhelds with Omni antennas with 2 meter downlinks from space. I hope we Continue to develop this mobile satellite capability. PCSAT and ARISS packet system demonstrate this easily.
De WB4APR, Bob
--- Robert Bruninga bruninga@usna.edu wrote:
Lets preserve 2m downlinks for OMNI directional downlinks to Mobiles and handhelds where the 19" mobile whip OMNI has a 9 dB advantage over 70cm and a 24 dB advantage over 2.4 GHz.
We can easily close the link to mobiles and handhelds with Omni antennas with 2 meter downlinks from space. I hope we Continue to develop this mobile satellite capability. PCSAT and ARISS packet system demonstrate this easily.
Bob raises a good point here.
What are peoples views on trying to get an Amateur Satellite Service allocation at 50-51 MHz ?
Granted omni antennas would be 3 times bigger than 2 metres but we would benefit from low path loss and low doppler shift ?
73 Trevor M5AKA
___________________________________________________________ All new Yahoo! Mail "The new Interface is stunning in its simplicity and ease of use." - PC Magazine http://uk.docs.yahoo.com/nowyoucan.html
Would the allocation be for Uplink only?
Kenneth - N5VHO
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Trevor Sent: Monday, September 11, 2006 4:24 PM To: AMSAT BB Subject: [amsat-bb] 50 MHz (was S band and Eagle: an appeal for a higherleveldiscussion)
--- Robert Bruninga bruninga@usna.edu wrote:
Lets preserve 2m downlinks for OMNI directional downlinks to Mobiles and handhelds where the 19" mobile whip OMNI has a 9 dB advantage over 70cm and a 24 dB advantage over 2.4 GHz.
We can easily close the link to mobiles and handhelds with Omni antennas with 2 meter downlinks from space. I hope we Continue to develop this mobile satellite capability. PCSAT and ARISS packet system demonstrate this easily.
Bob raises a good point here.
What are peoples views on trying to get an Amateur Satellite Service allocation at 50-51 MHz ?
Granted omni antennas would be 3 times bigger than 2 metres but we would benefit from low path loss and low doppler shift ?
73 Trevor M5AKA
___________________________________________________________ All new Yahoo! Mail "The new Interface is stunning in its simplicity and ease of use." - PC Magazine http://uk.docs.yahoo.com/nowyoucan.html _______________________________________________ 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
Ransom, Kenneth G. (JSC-OC)[BAR] escribió:
What are peoples views on trying to get an Amateur Satellite Service allocation at 50-51 MHz ?
First, we should get a worldwide amateur service allocation in the range 51-52 MHz. Many countries have (very) restricted access to 6m band, and others do not have allocation at all!
I wonder if the severe Sporadic E on 6m can affect to the satellite service at moderate and low angles... I suspect the answer is yes.
73!
______________________________________________ LLama Gratis a cualquier PC del Mundo. Llamadas a fijos y móviles desde 1 céntimo por minuto. http://es.voice.yahoo.com
At 01:12 AM 9/13/2006, Miguel A. Vallejo wrote:
Ransom, Kenneth G. (JSC-OC)[BAR] escribió:
What are peoples views on trying to get an Amateur Satellite Service allocation at 50-51 MHz ?
First, we should get a worldwide amateur service allocation in the range 51-52 MHz. Many countries have (very) restricted access to 6m band, and others do not have allocation at all!
Most VK amateurs aren't able to transmit on 50-52 MHz, except for the DX window at the very bottom of the band. That segment is still used for TV broadcasting down here (a small number of TV stations). Maybe the shift to digital TV around 2012 will offer a small window to get this part of the band (the low band is being phased out for TV broadcasting, and is not used by the digital service).
I wonder if the severe Sporadic E on 6m can affect to the satellite service at moderate and low angles... I suspect the answer is yes.
This could lead to all sorts of interesting effects...
73 de VK3JED http://vkradio.com
Why uplink only ?
Wherever possible it is desirable to have allocation that permit both Space-to-Earth and Earth-to-Space communications.
73 Trevor M5AKA --- "Ransom, Kenneth G. (JSC-OC)[BAR]" kenneth.g.ransom@nasa.gov wrote:
Would the allocation be for Uplink only?
Kenneth - N5VHO
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Trevor Sent: Monday, September 11, 2006 4:24 PM To: AMSAT BB Subject: [amsat-bb] 50 MHz (was S band and Eagle: an appeal for a higherleveldiscussion)
--- Robert Bruninga bruninga@usna.edu wrote:
Lets preserve 2m downlinks for OMNI directional downlinks to Mobiles and handhelds where the 19" mobile whip OMNI has a 9 dB advantage over 70cm and a 24 dB advantage over 2.4 GHz.
We can easily close the link to mobiles and handhelds with Omni antennas with 2 meter downlinks from space. I hope we Continue to develop this mobile satellite capability. PCSAT and ARISS packet system demonstrate this easily.
Bob raises a good point here.
What are peoples views on trying to get an Amateur Satellite Service allocation at 50-51 MHz ?
Granted omni antennas would be 3 times bigger than 2 metres but we would benefit from low path loss and low doppler shift ?
73 Trevor M5AKA
___________________________________________________________ All new Yahoo! Mail "The new Interface is stunning in its simplicity and ease of use." - PC Magazine http://uk.docs.yahoo.com/nowyoucan.html _______________________________________________ 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
------------- Chelmsford Amateur Radio Society ------------- Support Essex Air Ambulance - Apply for the Chelmsford Award See CARS website http://www.g0mwt.org.uk/ ------------------------------------------------------------
___________________________________________________________ All new Yahoo! Mail "The new Interface is stunning in its simplicity and ease of use." - PC Magazine http://uk.docs.yahoo.com/nowyoucan.html
participants (17)
-
Bruce Robertson -
Edward R. Cole -
Eric H Christensen -
Gary "Joe" Mayfield -
Greg D. -
i8cvs -
Joe Westbrook -
John B. Stephensen -
kc6uqh -
Kevin J. Smith -
Luc Leblanc VE2DWE -
Miguel A. Vallejo -
Ransom, Kenneth G. (JSC-OC)[BAR] -
Robert Bruninga -
Stefan Wagener -
Tony Langdon -
Trevor