[Fwd: [amsat-bb] Re: S band downlink on P3E]
Team: The kind of rational technical argument we should be prepared to answer. . . .
73, Jim
-------- Original Message -------- Subject: [amsat-bb] Re: S band downlink on P3E Date: Thu, 7 Sep 2006 17:40:39 -0400 From: Jeff Griffin kb2m@comcast.net Reply-To: Jeff Griffin kb2m@comcast.net To: amsat-bb@amsat.org References: 01b401c6d28f$cc51d870$1001a8c0@RAFPavillion 050e01c6d2ac$e29ff720$6401a8c0@KO4MA
Ok guy's, how about a test ? Why not everyone who is mode L/S capable get on AO-51 between September 11, and September 18th and post all results here? Or have another mode V/S session for the L band challenged? All we need is degree(s) of elevation worked, type of antenna, and rx environment, and quality of rx signal received. This should tell us what we want to know. I don't think there is a problem, as I worked up to 10 stations a pass last mode V/S session , and didn't hear anyone complain....
73 Jeff kb2m
----- Original Message ----- From: "Andrew Glasbrenner" glasbrenner@mindspring.com To: "Rick Fletcher" rfletcher@plumdragon.com; "'AMSAT'" amsat-bb@amsat.org Sent: Thursday, September 07, 2006 2:38 PM Subject: [amsat-bb] Re: S band downlink on P3E
Rick,
I am in _TOTAL_ agreement. I live in the suburbs of Tampa/St. Pete and never had an interference problem on my 3 foot dish. I have used the same dish to log well over a dozen WiFi access points in that immediate neighborhood. With properly designed equipment, all that trash on 2.4 ghz goes away with some elevation. What won't work is helixes with multiple sidelobes, and surplus dishes that let one whole polarity of noise right thru the back.
Everyone knows I'm a big supporter of AMSAT, but I gotta call it as I see it. It makes me think of "bait and switch" to collect money for a project featuring such a popular mode and then drop it.
The loss of Mode B on AO-40 caused a lot of the hardcore AO-10/AO-13 types to walk away, and that was tough to overcome. Now that we have, and we have people wanting S band, we leave them behind too. Even if it's a sound engineering decision (and that hasn't been proven to me) it's a horrid marketing decision. Bad mojo for a organization that lives on the donations of it's members.
Sorry if this causes any pain to those involved with Eagle, but I needed to get it off my chest.
73, Drew KO4MA AMSAT LM 2332
While AO-40 was still alive and I was working it from deep within "Silicon Valley", an area blanketed by WiFi, 2.4GHz cordless phones, etc., I discovered that a parabolic dish with a properly positioned and designed patch feed (slightly under-illuminating the dish and having no significant side-lobes) would bring in AO-40's S-band downlink very nicely and cleanly.
Of course, other feed or antenna types such as helical antennas/feeds were useless in that environment.
I have to admit that I don't buy the "too noisy" argument.
73,
Rick KG6IAL
_______________________________________________ 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
I have a few problems with this.
1 - It has bad selection bias. Amateurs who are already on satellites and who use S-band downlinks are the ones who don't have problems with interference. If they had interference, they wouldn't be on those bands. Additionally, people currently on satellites tend to be those with lots of space for big dishes. The point here is to open this up to people who won't, and would have more interference problems, since they live in denser areas and can't put up big dishes with lots of directional gain.
2 - Anecdotal "evidence" is pointless, especially since it is 5 years old. WiFi is a lot more popular now than it was 5 years ago.
3 - Could you justify putting up an X million dollar satellite that uses a band which is questionable at best, just because some complainers who don't actually volunteer to do anything say that it works for them?
4 - Why should we have to justify why we're not using a band? As we agreed at the SD meeting, we are looking at providing _services_ and the best way to do that, not how to best make use of old hardware, which wouldn't be usable anyway. X-band is usable too. Why isn't anyone asking us to justify not using it?
Matt
Jim Sanford wrote:
Team: The kind of rational technical argument we should be prepared to answer. . . .
73, Jim
-------- Original Message -------- Subject: [amsat-bb] Re: S band downlink on P3E Date: Thu, 7 Sep 2006 17:40:39 -0400 From: Jeff Griffin kb2m@comcast.net Reply-To: Jeff Griffin kb2m@comcast.net To: amsat-bb@amsat.org References: 01b401c6d28f$cc51d870$1001a8c0@RAFPavillion 050e01c6d2ac$e29ff720$6401a8c0@KO4MA
Ok guy's, how about a test ? Why not everyone who is mode L/S capable get on AO-51 between September 11, and September 18th and post all results here? Or have another mode V/S session for the L band challenged? All we need is degree(s) of elevation worked, type of antenna, and rx environment, and quality of rx signal received. This should tell us what we want to know. I don't think there is a problem, as I worked up to 10 stations a pass last mode V/S session , and didn't hear anyone complain....
73 Jeff kb2m
----- Original Message ----- From: "Andrew Glasbrenner" glasbrenner@mindspring.com To: "Rick Fletcher" rfletcher@plumdragon.com; "'AMSAT'" amsat-bb@amsat.org Sent: Thursday, September 07, 2006 2:38 PM Subject: [amsat-bb] Re: S band downlink on P3E
Rick,
I am in _TOTAL_ agreement. I live in the suburbs of Tampa/St. Pete and never had an interference problem on my 3 foot dish. I have used the same dish to log well over a dozen WiFi access points in that immediate neighborhood. With properly designed equipment, all that trash on 2.4 ghz goes away with some elevation. What won't work is helixes with multiple sidelobes, and surplus dishes that let one whole polarity of noise right thru the back.
Everyone knows I'm a big supporter of AMSAT, but I gotta call it as I see it. It makes me think of "bait and switch" to collect money for a project featuring such a popular mode and then drop it.
The loss of Mode B on AO-40 caused a lot of the hardcore AO-10/AO-13 types to walk away, and that was tough to overcome. Now that we have, and we have people wanting S band, we leave them behind too. Even if it's a sound engineering decision (and that hasn't been proven to me) it's a horrid marketing decision. Bad mojo for a organization that lives on the donations of it's members.
Sorry if this causes any pain to those involved with Eagle, but I needed to get it off my chest.
73, Drew KO4MA AMSAT LM 2332
While AO-40 was still alive and I was working it from deep within "Silicon Valley", an area blanketed by WiFi, 2.4GHz cordless phones, etc., I discovered that a parabolic dish with a properly positioned and designed patch feed (slightly under-illuminating the dish and having no significant side-lobes) would bring in AO-40's S-band downlink very nicely and cleanly.
Of course, other feed or antenna types such as helical antennas/feeds were useless in that environment.
I have to admit that I don't buy the "too noisy" argument.
73,
Rick KG6IAL
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
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
Matt: While I agree with you technically, I disagree about the justification.
These are our users (customers, in the service perspective) and they had certain expectations, created by us. Although we said all along that it might change, that was not remembered by the most vocal.
Our members deserve answers, which I'll provide shortly. Bob and I have been working hard on the SD report, which I think will justify it all, to those who read and evaluate it. They're the ones that count. I've JUST read several rational emails from people who don't like the decision, but understand it, based on what we've published. They are our best allies, and we should support and accommodate them.
Thanks for all your good work.
73, Jim wb4gcs@amsat.org
Matt Ettus wrote:
I have a few problems with this. 1 - It has bad selection bias. Amateurs who are already on satellites and who use S-band downlinks are the ones who don't have problems with interference. If they had interference, they wouldn't be on those bands. Additionally, people currently on satellites tend to be those with lots of space for big dishes. The point here is to open this up to people who won't, and would have more interference problems, since they live in denser areas and can't put up big dishes with lots of directional gain.
2 - Anecdotal "evidence" is pointless, especially since it is 5 years old. WiFi is a lot more popular now than it was 5 years ago.
3 - Could you justify putting up an X million dollar satellite that uses a band which is questionable at best, just because some complainers who don't actually volunteer to do anything say that it works for them?
4 - Why should we have to justify why we're not using a band? As we agreed at the SD meeting, we are looking at providing _services_ and the best way to do that, not how to best make use of old hardware, which wouldn't be usable anyway. X-band is usable too. Why isn't anyone asking us to justify not using it?
Matt
Jim Sanford wrote:
Team: The kind of rational technical argument we should be prepared to answer. . . .
73, Jim
-------- Original Message -------- Subject: [amsat-bb] Re: S band downlink on P3E Date: Thu, 7 Sep 2006 17:40:39 -0400 From: Jeff Griffin kb2m@comcast.net Reply-To: Jeff Griffin kb2m@comcast.net To: amsat-bb@amsat.org References: 01b401c6d28f$cc51d870$1001a8c0@RAFPavillion 050e01c6d2ac$e29ff720$6401a8c0@KO4MA
Ok guy's, how about a test ? Why not everyone who is mode L/S capable get on AO-51 between September 11, and September 18th and post all results here? Or have another mode V/S session for the L band challenged? All we need is degree(s) of elevation worked, type of antenna, and rx environment, and quality of rx signal received. This should tell us what we want to know. I don't think there is a problem, as I worked up to 10 stations a pass last mode V/S session , and didn't hear anyone complain....
73 Jeff kb2m
----- Original Message ----- From: "Andrew Glasbrenner" glasbrenner@mindspring.com To: "Rick Fletcher" rfletcher@plumdragon.com; "'AMSAT'" amsat-bb@amsat.org Sent: Thursday, September 07, 2006 2:38 PM Subject: [amsat-bb] Re: S band downlink on P3E
Rick,
I am in _TOTAL_ agreement. I live in the suburbs of Tampa/St. Pete and never had an interference problem on my 3 foot dish. I have used the same dish to log well over a dozen WiFi access points in that immediate neighborhood. With properly designed equipment, all that trash on 2.4 ghz goes away with some elevation. What won't work is helixes with multiple sidelobes, and surplus dishes that let one whole polarity of noise right thru the back.
Everyone knows I'm a big supporter of AMSAT, but I gotta call it as I see it. It makes me think of "bait and switch" to collect money for a project featuring such a popular mode and then drop it.
The loss of Mode B on AO-40 caused a lot of the hardcore AO-10/AO-13 types to walk away, and that was tough to overcome. Now that we have, and we have people wanting S band, we leave them behind too. Even if it's a sound engineering decision (and that hasn't been proven to me) it's a horrid marketing decision. Bad mojo for a organization that lives on the donations of it's members.
Sorry if this causes any pain to those involved with Eagle, but I needed to get it off my chest.
73, Drew KO4MA AMSAT LM 2332
While AO-40 was still alive and I was working it from deep within "Silicon Valley", an area blanketed by WiFi, 2.4GHz cordless phones, etc., I discovered that a parabolic dish with a properly positioned and designed patch feed (slightly under-illuminating the dish and having no significant side-lobes) would bring in AO-40's S-band downlink very nicely and cleanly.
Of course, other feed or antenna types such as helical antennas/feeds were useless in that environment.
I have to admit that I don't buy the "too noisy" argument.
73,
Rick KG6IAL
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
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
Jim:
I disagree with some of the things you have said here. They are our customers today. We want to serve them to the extent we can but we also need to serve the customers who will be there at the time of launch (whenever we guess that to be) and we need to build a service for the new customers we want to acquire. We have essentially built a business plan that brings in new customers while serving the older customers as well as we can.
Bob
Jim Sanford wrote:
Matt: While I agree with you technically, I disagree about the justification.
These are our users (customers, in the service perspective) and they had certain expectations, created by us. Although we said all along that it might change, that was not remembered by the most vocal.
Our members deserve answers, which I'll provide shortly. Bob and I have been working hard on the SD report, which I think will justify it all, to those who read and evaluate it. They're the ones that count. I've JUST read several rational emails from people who don't like the decision, but understand it, based on what we've published. They are our best allies, and we should support and accommodate them.
Thanks for all your good work.
73, Jim wb4gcs@amsat.org
Matt Ettus wrote:
I have a few problems with this. 1 - It has bad selection bias. Amateurs who are already on satellites and who use S-band downlinks are the ones who don't have problems with interference. If they had interference, they wouldn't be on those bands. Additionally, people currently on satellites tend to be those with lots of space for big dishes. The point here is to open this up to people who won't, and would have more interference problems, since they live in denser areas and can't put up big dishes with lots of directional gain.
2 - Anecdotal "evidence" is pointless, especially since it is 5 years old. WiFi is a lot more popular now than it was 5 years ago.
3 - Could you justify putting up an X million dollar satellite that uses a band which is questionable at best, just because some complainers who don't actually volunteer to do anything say that it works for them?
4 - Why should we have to justify why we're not using a band? As we agreed at the SD meeting, we are looking at providing _services_ and the best way to do that, not how to best make use of old hardware, which wouldn't be usable anyway. X-band is usable too. Why isn't anyone asking us to justify not using it?
Matt
Jim Sanford wrote:
Team: The kind of rational technical argument we should be prepared to answer. . . .
73, Jim
-------- Original Message -------- Subject: [amsat-bb] Re: S band downlink on P3E Date: Thu, 7 Sep 2006 17:40:39 -0400 From: Jeff Griffin kb2m@comcast.net Reply-To: Jeff Griffin kb2m@comcast.net To: amsat-bb@amsat.org References: 01b401c6d28f$cc51d870$1001a8c0@RAFPavillion 050e01c6d2ac$e29ff720$6401a8c0@KO4MA
Ok guy's, how about a test ? Why not everyone who is mode L/S capable get on AO-51 between September 11, and September 18th and post all results here? Or have another mode V/S session for the L band challenged? All we need is degree(s) of elevation worked, type of antenna, and rx environment, and quality of rx signal received. This should tell us what we want to know. I don't think there is a problem, as I worked up to 10 stations a pass last mode V/S session , and didn't hear anyone complain....
73 Jeff kb2m
----- Original Message ----- From: "Andrew Glasbrenner" glasbrenner@mindspring.com To: "Rick Fletcher" rfletcher@plumdragon.com; "'AMSAT'" amsat-bb@amsat.org Sent: Thursday, September 07, 2006 2:38 PM Subject: [amsat-bb] Re: S band downlink on P3E
Rick,
I am in _TOTAL_ agreement. I live in the suburbs of Tampa/St. Pete and never had an interference problem on my 3 foot dish. I have used the same dish to log well over a dozen WiFi access points in that immediate neighborhood. With properly designed equipment, all that trash on 2.4 ghz goes away with some elevation. What won't work is helixes with multiple sidelobes, and surplus dishes that let one whole polarity of noise right thru the back.
Everyone knows I'm a big supporter of AMSAT, but I gotta call it as I see it. It makes me think of "bait and switch" to collect money for a project featuring such a popular mode and then drop it.
The loss of Mode B on AO-40 caused a lot of the hardcore AO-10/AO-13 types to walk away, and that was tough to overcome. Now that we have, and we have people wanting S band, we leave them behind too. Even if it's a sound engineering decision (and that hasn't been proven to me) it's a horrid marketing decision. Bad mojo for a organization that lives on the donations of it's members.
Sorry if this causes any pain to those involved with Eagle, but I needed to get it off my chest.
73, Drew KO4MA AMSAT LM 2332
While AO-40 was still alive and I was working it from deep within "Silicon Valley", an area blanketed by WiFi, 2.4GHz cordless phones, etc., I discovered that a parabolic dish with a properly positioned and designed patch feed (slightly under-illuminating the dish and having no significant side-lobes) would bring in AO-40's S-band downlink very nicely and cleanly.
Of course, other feed or antenna types such as helical antennas/feeds were useless in that environment.
I have to admit that I don't buy the "too noisy" argument.
73,
Rick KG6IAL
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
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
I rarely post to this list but I hope you will accept my apologies for doing so on this topic.
At 05:31 PM 9/7/2006, Matt Ettus wrote:
I have a few problems with this.
1 - It has bad selection bias. Amateurs who are already on satellites and who use S-band downlinks are the ones who don't have problems with interference. If they had interference, they wouldn't be on those bands.
This is IMHO a very bad assumption. If this was a problem with AO-40 or AO-51 (since the assumption is the problem grew expotentially since 2003) then I think we would have heard volumes about it. We haven't. I would be the first to defend that AO-51 is not the best example to use, but I swept my yagi and downconverter around 360 degrees with my spectrum analyzer attached. The spikes were s1 or below. It's not a calibrated measurement, but I'd have to side with the "this isn't a problem" folks. So I feel strongly more tests are needed.
Additionally, people currently on satellites tend to be those with lots of space for big dishes.
I live in a townhouse - this is again a bad assumption. I work AO-51 with a Yagi for 2.4G. If the wind conditions here in San Mateo are light (which they generally aren't) I might put put up a 60CM dish, but generally I won't. Even with the Yagi - WiFi is not a problem.
The point here is to open this up to people who won't, and would have more interference problems, since they live in denser areas and can't put up big dishes with lots of directional gain.
San Mateo has almost a million people in a 12 mile radius. I get no little inteference in the lower S band, and only a very small amount of popping (that my DSP removes completely) in the upper S band. So I personally need more convincing that this isn't a problem. At worse we may have to convince our members to buy better downconverters or add on notch filters so that their wideband downconverters don't suck up noise from outside the band. But telling people to get a filter isn't a big inconvenience. It's been done before.
2 - Anecdotal "evidence" is pointless, especially since it is 5 years old. WiFi is a lot more popular now than it was 5 years ago.
Matt, I don't want to seem confrontational, but so far all I've seen is anecdotal eveidence from the Eagle team. I will admit I don't read everything, but I do read things more closely when I see things like camera shots from spectrum analyzers that are real experiments. I haven't seen it.
It is important to provide empirical data. I have a very open mind, but so far the only thing I've seen are predictions of impending doom and statistics, not hard data.
3 - Could you justify putting up an X million dollar satellite that uses a band which is questionable at best, just because some complainers who don't actually volunteer to do anything say that it works for them?
I think this is a very good question - so if that is the argument, why would you put up a mode U/V transponder? It's as usable as mud in a gas tank.
4 - Why should we have to justify why we're not using a band?
There are several reasons. The first is because we have spectrum allocated there, and if we don't use it we simply lose it. In the future we may need to rely upon it.
The other reason is because the people who bought into the technology 5-10 years ago have an investment that hasn't yet been fully realized. I don't want to go down the road questioning the judgement of people who told our customer base to go down the road, but if it was flawed we haven't told people we are sorry. It's also why none of the commercial broadcasters cut off analog TV transmissions when the FCC set the 2006 deadline. People hang on to technology.
As we agreed at the SD meeting, we are looking at providing _services_ and the best way to do that, not how to best make use of old hardware, which wouldn't be usable anyway.
I wasn't invited to that meeting, but can you tell me why you don't think it wouldn't be usable? I think that is a very bad assumption.
X-band is usable too. Why isn't anyone asking us to justify not using it?
I'm not an expert at that level of microwave technology, but I think that the biggest hurdle (and I could be slammed here) is that if we were to try to launch an X-Band satellite I'm not sure the baseband oscillator technology would be stable in space at a price we can afford. Rick can comment on that - he's the GPS expert and I'm commenting with only terrestrial experience. But putting a GPS corrected clock for X-Band stabilization is something we haven't tried before. However, perhaps we should, and I think the membership would get behind that experiment.
73,
Emily
The point here is to open this up to people who won't, and would have more interference problems, since they live in denser areas and can't put up big dishes with lots of directional gain.
San Mateo has almost a million people in a 12 mile radius. I get no little inteference in the lower S band, and only a very small amount of popping (that my DSP removes completely) in the upper S band. So I personally need more convincing that this isn't a problem. At worse we may have to convince our members to buy better downconverters or add on notch filters so that their wideband downconverters don't suck up noise from outside the band. But telling people to get a filter isn't a big inconvenience. It's been done before.
Only the upper S-band is a satellite band. If you get "pops" in a narrowband receiver, chances are that the noise is bad enough to make problems for a wideband receiver trying to receive signals at the background noise level. You can't use a notch filter if the interference is wideband and is on the wideband channel you are trying to receive.
3 - Could you justify putting up an X million dollar satellite that uses a band which is questionable at best, just because some complainers who don't actually volunteer to do anything say that it works for them?
I think this is a very good question - so if that is the argument, why would you put up a mode U/V transponder? It's as usable as mud in a gas tank.
If it were up to me, we wouldn't....
4 - Why should we have to justify why we're not using a band?
There are several reasons. The first is because we have spectrum allocated there, and if we don't use it we simply lose it. In the future we may need to rely upon it.
What band aren't we using? We're using S-band for uplink instead of downlink, bet we're still using it. How does that cause us to lose spectrum?
The other reason is because the people who bought into the technology 5-10 years ago have an investment that hasn't yet been fully realized. I don't want to go down the road questioning the judgement of people who told our customer base to go down the road, but if it was flawed we haven't told people we are sorry. It's also why none of the commercial broadcasters cut off analog TV transmissions when the FCC set the 2006 deadline. People hang on to technology.
As we agreed at the SD meeting, we are looking at providing _services_ and the best way to do that, not how to best make use of old hardware, which wouldn't be usable anyway.
I wasn't invited to that meeting, but can you tell me why you don't think it wouldn't be usable? I think that is a very bad assumption.
It wouldn't be usable, not because of interference. it wouldn't be usable because this is a wideband digital system, not the kind of thing where you just hook a downconverter up to your Icom. You need special hardware all the way from the antenna to the backend.
Matt
Emily: Go look at the article on EaglePedia discussing the SD meeting.
In the appendix you will see spectrum analyzer plots.
Thanks & 73, Jim wb4gcs@amsat.org
Emily Clarke wrote:
I rarely post to this list but I hope you will accept my apologies for doing so on this topic.
At 05:31 PM 9/7/2006, Matt Ettus wrote:
I have a few problems with this.
1 - It has bad selection bias. Amateurs who are already on satellites and who use S-band downlinks are the ones who don't have problems with interference. If they had interference, they wouldn't be on those bands.
This is IMHO a very bad assumption. If this was a problem with AO-40 or AO-51 (since the assumption is the problem grew expotentially since 2003) then I think we would have heard volumes about it. We haven't. I would be the first to defend that AO-51 is not the best example to use, but I swept my yagi and downconverter around 360 degrees with my spectrum analyzer attached. The spikes were s1 or below. It's not a calibrated measurement, but I'd have to side with the "this isn't a problem" folks. So I feel strongly more tests are needed.
Additionally, people currently on satellites tend to be those with lots of space for big dishes.
I live in a townhouse - this is again a bad assumption. I work AO-51 with a Yagi for 2.4G. If the wind conditions here in San Mateo are light (which they generally aren't) I might put put up a 60CM dish, but generally I won't. Even with the Yagi - WiFi is not a problem.
The point here is to open this up to people who won't, and would have more interference problems, since they live in denser areas and can't put up big dishes with lots of directional gain.
San Mateo has almost a million people in a 12 mile radius. I get no little inteference in the lower S band, and only a very small amount of popping (that my DSP removes completely) in the upper S band. So I personally need more convincing that this isn't a problem. At worse we may have to convince our members to buy better downconverters or add on notch filters so that their wideband downconverters don't suck up noise from outside the band. But telling people to get a filter isn't a big inconvenience. It's been done before.
2 - Anecdotal "evidence" is pointless, especially since it is 5 years old. WiFi is a lot more popular now than it was 5 years ago.
Matt, I don't want to seem confrontational, but so far all I've seen is anecdotal eveidence from the Eagle team. I will admit I don't read everything, but I do read things more closely when I see things like camera shots from spectrum analyzers that are real experiments. I haven't seen it.
It is important to provide empirical data. I have a very open mind, but so far the only thing I've seen are predictions of impending doom and statistics, not hard data.
3 - Could you justify putting up an X million dollar satellite that uses a band which is questionable at best, just because some complainers who don't actually volunteer to do anything say that it works for them?
I think this is a very good question - so if that is the argument, why would you put up a mode U/V transponder? It's as usable as mud in a gas tank.
4 - Why should we have to justify why we're not using a band?
There are several reasons. The first is because we have spectrum allocated there, and if we don't use it we simply lose it. In the future we may need to rely upon it.
The other reason is because the people who bought into the technology 5-10 years ago have an investment that hasn't yet been fully realized. I don't want to go down the road questioning the judgement of people who told our customer base to go down the road, but if it was flawed we haven't told people we are sorry. It's also why none of the commercial broadcasters cut off analog TV transmissions when the FCC set the 2006 deadline. People hang on to technology.
As we agreed at the SD meeting, we are looking at providing _services_ and the best way to do that, not how to best make use of old hardware, which wouldn't be usable anyway.
I wasn't invited to that meeting, but can you tell me why you don't think it wouldn't be usable? I think that is a very bad assumption.
X-band is usable too. Why isn't anyone asking us to justify not using it?
I'm not an expert at that level of microwave technology, but I think that the biggest hurdle (and I could be slammed here) is that if we were to try to launch an X-Band satellite I'm not sure the baseband oscillator technology would be stable in space at a price we can afford. Rick can comment on that - he's the GPS expert and I'm commenting with only terrestrial experience. But putting a GPS corrected clock for X-Band stabilization is something we haven't tried before. However, perhaps we should, and I think the membership would get behind that experiment.
73,
Emily
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
participants (4)
-
Emily Clarke -
Jim Sanford -
Matt Ettus -
Robert McGwier