Re: Why do the amsats get more and more complex?
Jason,
I can easily imagine how you may have come to the conclusion by listening to some people on amsat-bb that satellites are becoming bigger, more complex and more expensive while not providing you with better services. You might even think that AMSAT officials are not listening. Nothing could be further from the truth.
P3E is designed to provide services similar to AO-13 in an effort to make it smaller, cheaper and simpler than AO-40. It also will carry experiments essential to the future P5A mission to Mars. This is a very reasonable increase in complexity for a good purpose.
Eagle is intended to be a series of satellites. Eagle has been designed to be smaller, lighter and cheaper than AO-40. Its shape was designed to optimize a low inclination orbit like the one AO-40 attained. This unintended orbit turned out to be very attractive to many users and it provides for orbit stability and much less propulsion, further reducing mission risk. It also carries fewer payloads and these payloads have been specifically chosen to get the best performance for the maximum number of users.
Both P3E and Eagle have chosen Software Defined Transponders (SDXs) to implement the "linear transponder" functions for many reasons. Among these are efficiency, stability, linearity, cost, in-flight performance improvement, the ability to simultaneously share the transponder with other modes (Packet, APRS, SMS are possible examples), and the ability to change performance parameters in flight. This choice does not make the satellite bigger, more expensive, or less useful, etc. In fact, it is just the opposite.
Eagle will carry a payload that it is hoped will revolutionize Amateur Satellite communications and Ham Radio as a whole. Initially called C-C Rider, I will call it the Advanced Communications Package (ACP) because it no longer uses C-band for both uplink and downlink. This package will be designed to bring satellites and DX to you and to many other Hams who have never been able to use a satellite or operate DX before. This is because the ground station antenna will be small, power levels reasonable, many modes will be supported (from Voice and CW to Video and data communications), the ground station will be affordable and the signal quality will be superior. Much of this is accomplished through the use of digital techniques so it will require all new equipment on the ground. AMSAT will design the ground station equipment and publish everything so you can buy it, copy it, sell it, or build it.
The Eagle band plan has been the subject of much discussion, of late. Eagle is still in the design phase and the band plan is not finalized, so don't worry just yet. The confusion was the result of the ACP (C-C Rider) team realizing that they had to find another band for the uplink. They chose S-band for some good reasons but that recommendation is under review by the whole Eagle team and is not yet final. There should be a final announcement at the AMSAT Symposium in a few weeks. I encourage everyone to come to the Symposium and meet your AMSAT officials and learn what is really happening in AMSAT.
There is much more I could say but, in summary, the new satellites are getting better in every way compared to the old ones. The future is bright and we need your support and involvement to achieve these goals.
Rick W2GPS AMSAT President Subject: [amsat-bb] Why do the amsats get more and more complex? From: Jason White jason@xxxxxxxxxxxxxxxx Date: Tue, 19 Sep 2006 10:48:44 -0400
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This is intended to be an honest question that I've wanted to ask, but I don't want to spark controversy or long threads that monopolize the reflector. I have a feeling this could go either way, so I'm just asking politely that the thread not go that way! It's not my intent.
Anyway, I'm just curious why it seems that every new satellite project proposed seems to be bigger and more complex than the last? I keep hearing about exotic modes and uplink/downlink bands for P3E. Software defined transceivers, etc. etc. and what it looks like to me are more and more failure points. I understand the need to push the limits of technology as a justification for our very existence, but personally I feel like the designs are overly complicated and highly priced. I'm not ready to switch my earth station to SDRs, for instance.. I'm dubious about putting one into orbit.. then again, I'm not skilled enough to make those sorts of decisions.
What I'm getting at is that Oscar 7 proved how reliable older technology can be.. For the price of one of the phase 3 birds it seems like several Mode B linear transponder sats could be put up, or a few more FM sats. I personally would much rather see a modest mode B sat in AO-40s intended orbital pattern than to try to wrangle parts for microwave.
Did it get too easy for people or something?
Wouldn't it be better to separate out some of the more experimental stuff from the old standbys? That way a failure of one whole sat would still leave something usable for the same money spent. My vote would be to piggyback a completely independent analog satellite onto P3E "just in case".
Like I said, please, I'm looking for a real, thought out response. I didn't write the above to be a critique or to troll or anything like that, I am just curious because it seems to me, as an outside observer, that after the failure of AO-40 the direction was to go bigger and even more complicated, which left me cold considering what I had done at my station to work AO-40. Even when AO-40 was up I felt it was very odd that time and money were spent on components and systems that were never used (did the solar panels ever deploy?) Yes, I know the sat was damaged, and that explains a good bit of it, but it still felt like some things were wasted. Emphasis on "felt".. I couldn't know the real process that resulted in the decisions made.
If someone could help me understand why the direction is the way it is maybe I could get excited about the bigger sats, but I think you get more "bang for the buck" with the smaller less complicated birds. My favorite so far is PCSat I. Mostly off the shelf hardware and I had a very easy time digipeating APRS through it. One of those in an elliptical orbit would be a hoot!
73s,
Jason - N1XBP
P.S. - One last plea, this isn't a troll! I'm worried people will think it is.
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Maybe someone can explain why Eagle could not use the L Band for its digital uplink instead of S Band? Then you would have a L/C mode and many users already have a L band uplink capability.
Les W4SCO
Eagle will carry a payload that it is hoped will revolutionize Amateur Satellite communications and Ham Radio as a whole. Initially called C-C Rider, I will call it the Advanced Communications Package (ACP) because it no longer uses C-band for both uplink and downlink. This package will be designed to bring satellites and DX to you and to many other Hams who have never been able to use a satellite or operate DX before. This is because the ground station antenna will be small, power levels reasonable, many modes will be supported (from Voice and CW to Video and data communications), the ground station will be affordable and the signal quality will be superior. Much of this is accomplished through the use of digital techniques so it will require all new equipment on the ground. AMSAT will design the ground station equipment and publish everything so you can buy it, copy it, sell it, or build it.
The Eagle band plan has been the subject of much discussion, of late. Eagle is still in the design phase and the band plan is not finalized, so don't worry just yet. The confusion was the result of the ACP (C-C Rider) team realizing that they had to find another band for the uplink. They chose S-band for some good reasons but that recommendation is under review by the whole Eagle team and is not yet final. There should be a final announcement at the AMSAT Symposium in a few weeks. I encourage everyone to come to the Symposium and meet your AMSAT officials and learn what is really happening in AMSAT.
At 11:29 PM 9/19/2006, sco@sco-inc.com wrote:
Maybe someone can explain why Eagle could not use the L Band for its digital uplink instead of S Band? Then you would have a L/C mode and many users already have a L band uplink capability.
My understanding is that there is not enough room for an antenna of the size required for 1296, at least not one with much gain. I'm sure that someone from the engineering team could speak further to this.
This was heavily discussed each night at the DCC in Tucson, and antennas and band availability were discussed ad nauseam.
No one is trying to ignore the users - heck, why build it if there would be no users, but they WERE trying to make sound engineering arguments so that there would actually be something worthwhile available. One AMSAT member present, someone who I recognized as an operator with some experience, made a number of suggestions that the engineers seemed to embrace, so you may see some additional info come forward by the time of the AMSAT meeting.
Dave VE3GYQ/W8 Spencerville, OH
Les,
Don't forget, these issues are all under review as we speak.
The answer is in two parts. First, an L-band ground antenna would be too large to disguise as a TVRO dish. Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers.
I don't wish to debate these points. I'm just telling you the reasoning that went into not choosing L-band. I assure you that every possibility was considered. Lists were created and discussed on each alternative.
Rick W2GPS AMSAT LM2232
-----Original Message----- From: sco@sco-inc.com [mailto:sco@sco-inc.com] Sent: Tuesday, September 19, 2006 11:29 PM To: Rick Hambly (W2GPS) Cc: amsat-bb@amsat.org Subject: Re: [amsat-bb] Re: Why do the amsats get more and more complex?
Maybe someone can explain why Eagle could not use the L Band for its digital uplink instead of S Band? Then you would have a L/C mode and many users already have a L band uplink capability.
Les W4SCO
Eagle will carry a payload that it is hoped will revolutionize Amateur Satellite communications and Ham Radio as a whole. Initially called C-C Rider, I will call it the Advanced Communications Package (ACP) because it no longer uses C-band for both uplink and downlink. This package will be designed to bring satellites and DX to you and to many other Hams who have never been able to use a satellite or operate DX before. This is because the ground station antenna will be small, power levels reasonable, many modes will be supported (from Voice and CW to Video and data communications), the ground station will be affordable and the signal quality will be superior. Much of this is accomplished through the use of digital techniques so it will require all new equipment on the ground.
AMSAT
will design the ground station equipment and publish everything so you can buy it, copy it, sell it, or build it.
The Eagle band plan has been the subject of much discussion, of late.
Eagle
is still in the design phase and the band plan is not finalized, so don't worry just yet. The confusion was the result of the ACP (C-C Rider) team realizing that they had to find another band for the uplink. They chose S-band for some good reasons but that recommendation is under review by the whole Eagle team and is not yet final. There should be a final announcement at the AMSAT Symposium in a few weeks. I encourage everyone to come to the Symposium and meet your AMSAT officials and learn what is really happening in AMSAT.
Galileo (if it is ever built and launched and worked) would just be over Europe, right? That would leave the rest of the world the ability to use our L band uplink, right? If we hams are using a dish pointed at the sky with a narrow bandwidth how is that going to interfere with ground receivers some distance from us? We would be smart enough to not have the Eagle uplink on the same freq, right? And we would design Eagle such that we could (from ground control) move the Eagle receive freq away from any potential conflict with Galileo, right? And Eagle would be in orbit and operational long before Galileo, right? And Galileo receivers on the ground will have the ability to cut out any possible interference from us, right?
Seems to me that we are planning to give up the L band (as an uplink) based on a lot of bad assumptions.
Les W4SCO
The answer is in two parts. First, an L-band ground antenna would be too large to disguise as a TVRO dish. Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers.
I don't wish to debate these points. I'm just telling you the reasoning that went into not choosing L-band. I assure you that every possibility was considered. Lists were created and discussed on each alternative.
Rick W2GPS AMSAT LM2232
Unfortunately, the Gaileo downlink covers 1258-1299 MHz, the first satellite has been lanched and the satellites in the constellation will be on over the entire world. Our uplink antennas have sidelobes that are 10-20 dB down, so a 1 kW EIRP SSB uplink results in 10-100 W radiated towards terrestrial receivers. A 256 kbps uplink would require 16 kW EIRP and be 0.5-1 MHz wide.
P3E has a second L receiver tuned to a null in the Galileo signal (there is only one null in the 1260-1270 MHz band) but no one knows if this will help. SSB users can move to the U uplink if L is a problem. However, this only works for narrowband signals. A wideband uplink won't fit in the null and can't move down in frequency.
73,
John KD6OZH
----- Original Message ----- From: sco@sco-inc.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 16:16 UTC Subject: [amsat-bb] Re: Why do the amsats get more and more complex?
Galileo (if it is ever built and launched and worked) would just be over Europe, right? That would leave the rest of the world the ability to use our L band uplink, right? If we hams are using a dish pointed at the sky with a narrow bandwidth how is that going to interfere with ground receivers some distance from us? We would be smart enough to not have the Eagle uplink on the same freq, right? And we would design Eagle such that we could (from ground control) move the Eagle receive freq away from any potential conflict with Galileo, right? And Eagle would be in orbit and operational long before Galileo, right? And Galileo receivers on the ground will have the ability to cut out any possible interference from us, right?
Seems to me that we are planning to give up the L band (as an uplink) based on a lot of bad assumptions.
Les W4SCO
The answer is in two parts. First, an L-band ground antenna would be too large to disguise as a TVRO dish. Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers.
I don't wish to debate these points. I'm just telling you the reasoning that went into not choosing L-band. I assure you that every possibility was considered. Lists were created and discussed on each alternative.
Rick W2GPS AMSAT LM2232
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
John,
Galileo is circularly polarized, so using the opposite polarization sense will help.
An excellent paper on Galileo interference was written by Peter Blair, G3LTF, a well known moonbounce authority and outstanding engineer. The paper can be found following this link:
http://www.southgatearc.org/articles/galileo.htm
73, Marc N2UO
--- "John B. Stephensen" kd6ozh@comcast.net wrote:
Unfortunately, the Gaileo downlink covers 1258-1299 MHz, the first satellite has been lanched and the satellites in the constellation will be on over the entire world. Our uplink antennas have sidelobes that are 10-20 dB down, so a 1 kW EIRP SSB uplink results in 10-100 W radiated towards terrestrial receivers. A 256 kbps uplink would require 16 kW EIRP and be 0.5-1 MHz wide.
P3E has a second L receiver tuned to a null in the Galileo signal (there is only one null in the 1260-1270 MHz band) but no one knows if this will help. SSB users can move to the U uplink if L is a problem. However, this only works for narrowband signals. A wideband uplink won't fit in the null and can't move down in frequency.
73,
John KD6OZH
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The article predicts that there may be limitations on the amateur service. The biggest problem is sidelobes from the antenna that can be of either polarization sense. A 16 kW EIRP uplink can easily generate 500 W EIRP sidelobes (15 dB down) within the Galileo receiver passband and, replicating the calculations outlined in the article, they can cause interference from 42 km away.
73,
John KD6OZH
----- Original Message ----- From: "Marc Franco" lu6dw@yahoo.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 19:03 UTC Subject: [amsat-bb] Galileo interference on L band
John,
Galileo is circularly polarized, so using the opposite polarization sense will help.
An excellent paper on Galileo interference was written by Peter Blair, G3LTF, a well known moonbounce authority and outstanding engineer. The paper can be found following this link:
http://www.southgatearc.org/articles/galileo.htm
73, Marc N2UO
--- "John B. Stephensen" kd6ozh@comcast.net wrote:
Unfortunately, the Gaileo downlink covers 1258-1299 MHz, the first satellite has been lanched and the satellites in the constellation will be on over the entire world. Our uplink antennas have sidelobes that are 10-20 dB down, so a 1 kW EIRP SSB uplink results in 10-100 W radiated towards terrestrial receivers. A 256 kbps uplink would require 16 kW EIRP and be 0.5-1 MHz wide.
P3E has a second L receiver tuned to a null in the Galileo signal (there is only one null in the 1260-1270 MHz band) but no one knows if this will help. SSB users can move to the U uplink if L is a problem. However, this only works for narrowband signals. A wideband uplink won't fit in the null and can't move down in frequency.
73,
John KD6OZH
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----- Original Message ----- From: "John B. Stephensen" kd6ozh@comcast.net To: "Marc Franco" lu6dw@yahoo.com; amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 10:13 PM Subject: [amsat-bb] Re: Galileo interference on L band
The article predicts that there may be limitations on the amateur service. The biggest problem is sidelobes from the antenna that can be of either polarization sense. A 16 kW EIRP uplink can easily generate 500 W EIRP sidelobes (15 dB down) within the Galileo receiver passband and,
replicating
the calculations outlined in the article, they can cause interference from 42 km away.
73,
John KD6OZH
Hi John, KD6OZH
Does this imply that all 23 cm EME stations including G3LTF will have to move away from 1296 MHz ?
73" de
i8CVS Domenico
----- Original Message ----- From: "Marc Franco" lu6dw@yahoo.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 19:03 UTC Subject: [amsat-bb] Galileo interference on L band
John,
Galileo is circularly polarized, so using the opposite polarization sense will help.
An excellent paper on Galileo interference was written by Peter Blair, G3LTF, a well known moonbounce authority and outstanding engineer. The paper can be found following this link:
http://www.southgatearc.org/articles/galileo.htm
73, Marc N2UO
--- "John B. Stephensen" kd6ozh@comcast.net wrote:
Unfortunately, the Gaileo downlink covers 1258-1299 MHz, the first satellite has been lanched and the satellites in the constellation will be on over the entire world. Our uplink antennas have sidelobes that are 10-20 dB down, so a 1 kW EIRP SSB uplink results in 10-100 W radiated towards terrestrial receivers. A 256 kbps uplink would require 16 kW EIRP and be 0.5-1 MHz wide.
P3E has a second L receiver tuned to a null in the Galileo signal (there is only one null in the 1260-1270 MHz band) but no one knows if this will help. SSB users can move to the U uplink if L is a problem. However, this only works for narrowband signals. A wideband uplink won't fit in the null and can't move down in frequency.
73,
John KD6OZH
The 1215-1240 MHz portion of our 23 cm band was deleted to protect GPS, so it could happen again.
73,
John KD6OZH
----- Original Message ----- From: "i8cvs" domenico.i8cvs@tin.it To: "John B. Stephensen" kd6ozh@comcast.net; "Marc Franco" lu6dw@yahoo.com; amsat-bb@amsat.org Sent: Thursday, September 21, 2006 04:15 UTC Subject: Re: [amsat-bb] Re: Galileo interference on L band
----- Original Message ----- From: "John B. Stephensen" kd6ozh@comcast.net To: "Marc Franco" lu6dw@yahoo.com; amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 10:13 PM Subject: [amsat-bb] Re: Galileo interference on L band
The article predicts that there may be limitations on the amateur service. The biggest problem is sidelobes from the antenna that can be of either polarization sense. A 16 kW EIRP uplink can easily generate 500 W EIRP sidelobes (15 dB down) within the Galileo receiver passband and,
replicating
the calculations outlined in the article, they can cause interference from 42 km away.
73,
John KD6OZH
Hi John, KD6OZH
Does this imply that all 23 cm EME stations including G3LTF will have to move away from 1296 MHz ?
73" de
i8CVS Domenico
----- Original Message ----- From: "Marc Franco" lu6dw@yahoo.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 19:03 UTC Subject: [amsat-bb] Galileo interference on L band
John,
Galileo is circularly polarized, so using the opposite polarization sense will help.
An excellent paper on Galileo interference was written by Peter Blair, G3LTF, a well known moonbounce authority and outstanding engineer. The paper can be found following this link:
http://www.southgatearc.org/articles/galileo.htm
73, Marc N2UO
--- "John B. Stephensen" kd6ozh@comcast.net wrote:
Unfortunately, the Gaileo downlink covers 1258-1299 MHz, the first satellite has been lanched and the satellites in the constellation will be on over the entire world. Our uplink antennas have sidelobes that are 10-20 dB down, so a 1 kW EIRP SSB uplink results in 10-100 W radiated towards terrestrial receivers. A 256 kbps uplink would require 16 kW EIRP and be 0.5-1 MHz wide.
P3E has a second L receiver tuned to a null in the Galileo signal (there is only one null in the 1260-1270 MHz band) but no one knows if this will help. SSB users can move to the U uplink if L is a problem. However, this only works for narrowband signals. A wideband uplink won't fit in the null and can't move down in frequency.
73,
John KD6OZH
--- "John B. Stephensen" kd6ozh@comcast.net wrote:
The 1215-1240 MHz portion of our 23 cm band was deleted to protect GPS, so it could happen again.
The battle for 1260-1300 was lost 6 years ago at WRC 2000 we need to ensure we keep vigilant for future challenges.
There are no Primary Amateur Satellite Service allocations between 146 MHz and 24 GHz. We need just a few MHz of primary allocations at key points in that spectrum.
BTW Peter Blair G3LTF's paper on Galileo can be seen at
http://www.southgatearc.org/articles/galileo.htm
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Allow me to add (AGAIN) for emphasis that the issue is the near/far problem. Maybe I should explain this in more detail as I think John and I are assuming that while you might not necessarily be able to calculate the exact path loss, you had an intutive understanding for the problem. The differences in distances are ENORMOUS. The Galileo satellites will typically be something like the circumference of the earth away from you and the best case is 1/2 the circumference of the earth.
The path loss from Galileo to your location is in the very best case given the planned orbit is approximately 180 dB.
The path loss from you to your neighbor a km away is about 93 dB. 100km improves this by approximately 55 dB. That is, ANY interference from your station given equal powers is inherently 87 dB stronger at the ground station than Galileo at 1 km and at 100 km, it is inherently ~30 dB stronger. Even if you factor in different powers on the spacecraft and ground, and losses from circularity, polarization, sidelobes, blah blah, 10^9 is a BILLION times advantage for your signal to clobber the Galileo signal before you take these into account. This calculation does not include any shaping of the beam on your part so a few dB gain in the direction of the ground station and the problem is worse. As the airplane approaches your location from 100 km, you will overload the front end without drastic measures taken by the manufacturers.
Please understand the engineers designing the Galileo system understand these issues well. They will argue very strongly that the interference sources be removed since they do not wish to notch you by 90 dB!
Bob N4HY
John B. Stephensen wrote:
The article predicts that there may be limitations on the amateur service. The biggest problem is sidelobes from the antenna that can be of either polarization sense. A 16 kW EIRP uplink can easily generate 500 W EIRP sidelobes (15 dB down) within the Galileo receiver passband and, replicating the calculations outlined in the article, they can cause interference from 42 km away.
73,
John KD6OZH
----- Original Message ----- From: "Marc Franco" lu6dw@yahoo.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 19:03 UTC Subject: [amsat-bb] Galileo interference on L band
John,
Galileo is circularly polarized, so using the opposite polarization sense will help.
An excellent paper on Galileo interference was written by Peter Blair, G3LTF, a well known moonbounce authority and outstanding engineer. The paper can be found following this link:
http://www.southgatearc.org/articles/galileo.htm
73, Marc N2UO
--- "John B. Stephensen" kd6ozh@comcast.net wrote:
Unfortunately, the Gaileo downlink covers 1258-1299 MHz, the first satellite has been lanched and the satellites in the constellation will be on over the entire world. Our uplink antennas have sidelobes that are 10-20 dB down, so a 1 kW EIRP SSB uplink results in 10-100 W radiated towards terrestrial receivers. A 256 kbps uplink would require 16 kW EIRP and be 0.5-1 MHz wide.
P3E has a second L receiver tuned to a null in the Galileo signal (there is only one null in the 1260-1270 MHz band) but no one knows if this will help. SSB users can move to the U uplink if L is a problem. However, this only works for narrowband signals. A wideband uplink won't fit in the null and can't move down in frequency.
73,
John KD6OZH
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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 understand this argument. BUT what i do not understand is the idea that an airliner would only be receiving one of the three bands that Galileo is saying that it intends to use for GPS. The L band is in just one of those three bands that the airplane would be receiving. Would the system not require the receiver to take data from the best signal? Could we not ask the FAA to require any airborne receiver that it certify must receive all three bands and switch bands if it receives any interference?
As a practical matter G GPS is not now in orbit, it would take years before it could be funded, launched and be operational. Then it would take the FAA probably another 10 years before they would certify it for use. I see 10-15-20 years before Galileo might be a problem to hams.
Why not fly Eagle with a backup L/S linear and use C/X for the digital transponder?
Les
At 12:15 PM 9/21/2006, Bob McGwier wrote:
Allow me to add (AGAIN) for emphasis that the issue is the near/far problem. Maybe I should explain this in more detail as I think John and I are assuming that while you might not necessarily be able to calculate the exact path loss, you had an intutive understanding for the problem. The differences in distances are ENORMOUS. The Galileo satellites will typically be something like the circumference of the earth away from you and the best case is 1/2 the circumference of the earth.
The path loss from Galileo to your location is in the very best case given the planned orbit is approximately 180 dB.
The path loss from you to your neighbor a km away is about 93 dB. 100km improves this by approximately 55 dB. That is, ANY interference from your station given equal powers is inherently 87 dB stronger at the ground station than Galileo at 1 km and at 100 km, it is inherently ~30 dB stronger. Even if you factor in different powers on the spacecraft and ground, and losses from circularity, polarization, sidelobes, blah blah, 10^9 is a BILLION times advantage for your signal to clobber the Galileo signal before you take these into account. This calculation does not include any shaping of the beam on your part so a few dB gain in the direction of the ground station and the problem is worse. As the airplane approaches your location from 100 km, you will overload the front end without drastic measures taken by the manufacturers.
Please understand the engineers designing the Galileo system understand these issues well. They will argue very strongly that the interference sources be removed since they do not wish to notch you by 90 dB!
Bob N4HY
John B. Stephensen wrote:
The article predicts that there may be limitations on the amateur service. The biggest problem is sidelobes from the antenna that can be of either polarization sense. A 16 kW EIRP uplink can easily generate 500 W EIRP sidelobes (15 dB down) within the Galileo receiver passband and,
replicating
the calculations outlined in the article, they can cause interference from 42 km away.
73,
John KD6OZH
----- Original Message ----- From: "Marc Franco" lu6dw@yahoo.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 19:03 UTC Subject: [amsat-bb] Galileo interference on L band
John,
Galileo is circularly polarized, so using the opposite polarization sense will help.
An excellent paper on Galileo interference was written by Peter Blair, G3LTF, a well known moonbounce authority and outstanding engineer. The paper can be found following this link:
http://www.southgatearc.org/articles/galileo.htm
73, Marc N2UO
--- "John B. Stephensen" kd6ozh@comcast.net wrote:
Unfortunately, the Gaileo downlink covers 1258-1299 MHz, the first satellite has been lanched and the satellites in the constellation will be on over the entire world. Our uplink antennas have sidelobes that are 10-20 dB down, so a 1 kW EIRP SSB uplink results in 10-100 W radiated towards terrestrial receivers. A 256 kbps uplink would require 16 kW EIRP and be 0.5-1 MHz wide.
P3E has a second L receiver tuned to a null in the Galileo signal (there is only one null in the 1260-1270 MHz band) but no one knows if this will help. SSB users can move to the U uplink if L is a problem. However, this only works for narrowband signals. A wideband uplink won't fit in the null and can't move down in frequency.
73,
John KD6OZH
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High-accuracy receivers use multiple downlink frequencies to compensate for errors, such as those induced by the ionosphere. There are probably 3 downlink frequencies in case 1 fails.
73,
John KD6OZH
----- Original Message ----- From: sco@sco-inc.com To: "amsat bb" amsat-bb@amsat.org Sent: Thursday, September 21, 2006 16:54 UTC Subject: [amsat-bb] Re: Galileo interference on L band
I understand this argument. BUT what i do not understand is the idea that an airliner would only be receiving one of the three bands that Galileo is saying that it intends to use for GPS. The L band is in just one of those three bands that the airplane would be receiving. Would the system not require the receiver to take data from the best signal? Could we not ask the FAA to require any airborne receiver that it certify must receive all three bands and switch bands if it receives any interference?
As a practical matter G GPS is not now in orbit, it would take years before it could be funded, launched and be operational. Then it would take the FAA probably another 10 years before they would certify it for use. I see 10-15-20 years before Galileo might be a problem to hams.
Why not fly Eagle with a backup L/S linear and use C/X for the digital transponder?
Les
At 12:15 PM 9/21/2006, Bob McGwier wrote:
Allow me to add (AGAIN) for emphasis that the issue is the near/far problem. Maybe I should explain this in more detail as I think John and I are assuming that while you might not necessarily be able to calculate the exact path loss, you had an intutive understanding for the problem. The differences in distances are ENORMOUS. The Galileo satellites will typically be something like the circumference of the earth away from you and the best case is 1/2 the circumference of the earth.
The path loss from Galileo to your location is in the very best case given the planned orbit is approximately 180 dB.
The path loss from you to your neighbor a km away is about 93 dB. 100km improves this by approximately 55 dB. That is, ANY interference from your station given equal powers is inherently 87 dB stronger at the ground station than Galileo at 1 km and at 100 km, it is inherently ~30 dB stronger. Even if you factor in different powers on the spacecraft and ground, and losses from circularity, polarization, sidelobes, blah blah, 10^9 is a BILLION times advantage for your signal to clobber the Galileo signal before you take these into account. This calculation does not include any shaping of the beam on your part so a few dB gain in the direction of the ground station and the problem is worse. As the airplane approaches your location from 100 km, you will overload the front end without drastic measures taken by the manufacturers.
Please understand the engineers designing the Galileo system understand these issues well. They will argue very strongly that the interference sources be removed since they do not wish to notch you by 90 dB!
Bob N4HY
John B. Stephensen wrote:
The article predicts that there may be limitations on the amateur service. The biggest problem is sidelobes from the antenna that can be of either polarization sense. A 16 kW EIRP uplink can easily generate 500 W EIRP sidelobes (15 dB down) within the Galileo receiver passband and,
replicating
the calculations outlined in the article, they can cause interference from 42 km away.
73,
John KD6OZH
----- Original Message ----- From: "Marc Franco" lu6dw@yahoo.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 19:03 UTC Subject: [amsat-bb] Galileo interference on L band
John,
Galileo is circularly polarized, so using the opposite polarization sense will help.
An excellent paper on Galileo interference was written by Peter Blair, G3LTF, a well known moonbounce authority and outstanding engineer. The paper can be found following this link:
http://www.southgatearc.org/articles/galileo.htm
73, Marc N2UO
--- "John B. Stephensen" kd6ozh@comcast.net wrote:
Unfortunately, the Gaileo downlink covers 1258-1299 MHz, the first satellite has been lanched and the satellites in the constellation will be on over the entire world. Our uplink antennas have sidelobes that are 10-20 dB down, so a 1 kW EIRP SSB uplink results in 10-100 W radiated towards terrestrial receivers. A 256 kbps uplink would require 16 kW EIRP and be 0.5-1 MHz wide.
P3E has a second L receiver tuned to a null in the Galileo signal (there is only one null in the 1260-1270 MHz band) but no one knows if this will help. SSB users can move to the U uplink if L is a problem. However, this only works for narrowband signals. A wideband uplink won't fit in the null and can't move down in frequency.
73,
John KD6OZH
Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ 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
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-- Robert W. McGwier, Ph.D. Center for Communications Research 805 Bunn Drive Princeton, NJ 08540 (609)-924-4600 (sig required by employer)
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John B. Stephensen wrote:
High-accuracy receivers use multiple downlink frequencies to compensate for errors, such as those induced by the ionosphere. There are probably 3 downlink frequencies in case 1 fails.
73,
John KD6OZH
----- Original Message ----- From: sco@sco-inc.com To: "amsat bb" amsat-bb@amsat.org Sent: Thursday, September 21, 2006 16:54 UTC Subject: [amsat-bb] Re: Galileo interference on L band
I understand this argument. BUT what i do not understand is the idea that an airliner would only be receiving one of the three bands that Galileo is saying that it intends to use for GPS. The L band is in just one of those three bands that the airplane would be receiving. Would the system not require the receiver to take data from the best signal? Could we not ask the FAA to require any airborne receiver that it certify must receive all three bands and switch bands if it receives any interference?
As a practical matter G GPS is not now in orbit, it would take years before it could be funded, launched and be operational. Then it would take the FAA probably another 10 years before they would certify it for use. I see 10-15-20 years before Galileo might be a problem to hams.
Why not fly Eagle with a backup L/S linear and use C/X for the digital transponder?
This debate grows more interesting with time.
Current publicly available Galileo documentation indicates that "Safety of Life" services will be provided on E5a/E5b (1164 to 1215 MHz) downlink and the E2/L1/E1 (1559 to 1591 MHz) downlink. The E6 (1260 to 1300 MHz) downlink is designated for 'commercial services' and not the aviation. Thus, I am VERY curious why the interference to aircraft navigation receivers is constantly brought up in this discussion as it appears a non-player.
For all but the most precise needs, dual frequency capabilities will eliminate the 1st order ionospheric errors leaving only the 2nd and 3rd order terms which are on the centimeter level. Thus I don't see the need for aircraft navigation systems to employ 'tri-frequency' receivers.
What am I missing here?
Thanks Bruce for your input. It seems to have quieted the crowd.
You wrote (and it's worth repeating!!)
"This debate grows more interesting with time.
Current publicly available Galileo documentation indicates that "Safety of Life" services will be provided on E5a/E5b (1164 to 1215 MHz) downlink and the E2/L1/E1 (1559 to 1591 MHz) downlink. The E6 (1260 to 1300 MHz) downlink is designated for 'commercial services' and not the aviation. Thus, I am VERY curious why the interference to aircraft navigation receivers is constantly brought up in this discussion as it appears a non-player.
For all but the most precise needs, dual frequency capabilities will eliminate the 1st order ionospheric errors leaving only the 2nd and 3rd order terms which are on the centimeter level. Thus I don't see the need for aircraft navigation systems to employ 'tri-frequency' receivers.
What am I missing here?
So, interference in the "safety for life" band is of interest to the government, and lots of testing, backups, and certification will be required to use it. Interference in the "commercial" band is of interest to Galileo's bottom line ($$), and they will be motivated ($$, again) to invest the least for the best payback. My worry is that it may appear cheaper to them to try to ban all other uses of those frequencies, than to invest in the engineering design and end-user hardware components to prevent that service from going down. Loss of life due to interference cannot be tolerated, of course, but to see what motivates action, follow the money.
Greg KO6TH
----Original Message Follows---- From: Bruce Rahn brahn@woh.rr.com Reply-To: brahn@woh.rr.com To: "John B. Stephensen" kd6ozh@comcast.net CC: amsat bb amsat-bb@amsat.org Subject: [amsat-bb] Re: Galileo interference on L band Date: Thu, 21 Sep 2006 14:28:21 -0400
John B. Stephensen wrote:
High-accuracy receivers use multiple downlink frequencies to compensate
for
errors, such as those induced by the ionosphere. There are probably 3 downlink frequencies in case 1 fails.
73,
John KD6OZH
----- Original Message ----- From: sco@sco-inc.com To: "amsat bb" amsat-bb@amsat.org Sent: Thursday, September 21, 2006 16:54 UTC Subject: [amsat-bb] Re: Galileo interference on L band
I understand this argument. BUT what i do not understand is the idea that an airliner would only be receiving one of the three bands that Galileo is saying that it intends to use for GPS. The L band is in just one of those three bands that the airplane would be receiving. Would the system not require the receiver to take data from the best signal? Could we not ask the FAA to require any airborne receiver that it certify must receive all three bands and switch bands if it receives any interference?
As a practical matter G GPS is not now in orbit, it would take years before it could be funded, launched and be operational. Then it would take the FAA probably another 10 years before they would certify it for use. I see 10-15-20 years before Galileo might be a problem to
hams.
Why not fly Eagle with a backup L/S linear and use C/X for the digital transponder?
This debate grows more interesting with time.
Current publicly available Galileo documentation indicates that "Safety of Life" services will be provided on E5a/E5b (1164 to 1215 MHz) downlink and the E2/L1/E1 (1559 to 1591 MHz) downlink. The E6 (1260 to 1300 MHz) downlink is designated for 'commercial services' and not the aviation. Thus, I am VERY curious why the interference to aircraft navigation receivers is constantly brought up in this discussion as it appears a non-player.
For all but the most precise needs, dual frequency capabilities will eliminate the 1st order ionospheric errors leaving only the 2nd and 3rd order terms which are on the centimeter level. Thus I don't see the need for aircraft navigation systems to employ 'tri-frequency' receivers.
What am I missing here?
-- Bruce Rahn
Wisdom has two parts: 1. having a lot to say; and 2. not saying it!
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Wireless 1.2 GHz cameras
I just picked up one of these little $60 cameras and am glad to report that they are not in the Amateur Allocation. They are 40 MHz wide each (4 channels) starting at 1060-1100, 1100-1140, 1140-1180, 1180-1220. But I was impressed with their range. An easy 1000' with the supplied receiver. My guess is about 5 milliwatts ERP. The energy at the edges was more than 60 dB down...
We also got a 2.4 GHz camera, and I was surprised that omni-to-omni, it too, did the 1000' LOS easily. My spectrum analyzer does not go high enough to see it. But what impressed me was that the little cameras did not appear to have any out-of band spurs (though I could not look at 2.4 GHz which would be the 2nd harmonic.)..
Doesn't mean much, but I did the test, so I thought I'd share it.
Bob, Wb4APR
Lets see, I should be able to get 10 dB easy with a corner reflector on both TX and RX and so I should be able to get 20 dB link gain for point-to-point and extend that 1000' range to 2 miles (LOS only). This is starting to look like its time to put this baby up on the ole'water tower with a remote control link. Do something like 15 dB gain antennas and this could be 5 miles or so...
Hi Bob,
While I do concur that Galileo interference is a "potential but currently unknown" problem, I'm approaching the issue with confidence that their design teams will find ways to handle the potential interference issues they appear to be well aware of.
Just look at their report "Galileo Interference Measurement Campaign" at: http://www.joanneum.at/index.php?id=530&L=1 and you will read about the many sources of potential interference they will need to be concerned about. In all their travels they found only one source of Amateur interference: an Amateur TV repeater. (I guess AO-51 wasn't in the L/S or L/U mode at the time of their trip!)
Not only must the Galileo system be designed to handle terrestrial interference but now that the GPS and Galileo frequencies have overlap they must handle mutual interference. I can reference reports on that issue too.
Then too - the Galileo E6 signal (pilot carrier at 1276 Mhz) has a significant null region around 1260+ Mhz. Now that's the lower end of our Amateur satellite band. P3E has L2 located there (good choice guys and gals!) and I would trust that is where you plan on locating Eagle's L-Band receiver.
By the way, the upper null falls around 1296 MHz so EME activities may also be able to co-exist.
This isn't the first time Amateurs had to deal with interference sources and surely won't be the last (i.e. power line internet), but we can't just admit defeat so early in the game - vacant our use of L-Band - and make the job of regulators who might wish to take the allocation away from us any easier than necessary.
Again, I think we can co-exist - my positive outlook. Naturally we must stay in touch with their progress and I would further suggest we establish a dialog with them early on to indicate to them we are aware of the potential for interference we could cause and try to "work with them" to find areas of mitigation.
Admittedly a tall task but surely its worthy of an attempt. In other words - try to get on their good side early in the game and let's take a pro-active approach to this potential problem!
Regards...Bill - N6GHz
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org]On Behalf Of Bob McGwier Sent: Thursday, September 21, 2006 9:16 AM To: John B. Stephensen Cc: amsat-bb@amsat.org Subject: [amsat-bb] Re: Galileo interference on L band
Allow me to add (AGAIN) for emphasis that the issue is the near/far problem. Maybe I should explain this in more detail as I think John and I are assuming that while you might not necessarily be able to calculate the exact path loss, you had an intutive understanding for the problem. The differences in distances are ENORMOUS. The Galileo satellites will typically be something like the circumference of the earth away from you and the best case is 1/2 the circumference of the earth.
The path loss from Galileo to your location is in the very best case given the planned orbit is approximately 180 dB.
The path loss from you to your neighbor a km away is about 93 dB. 100km improves this by approximately 55 dB. That is, ANY interference from your station given equal powers is inherently 87 dB stronger at the ground station than Galileo at 1 km and at 100 km, it is inherently ~30 dB stronger. Even if you factor in different powers on the spacecraft and ground, and losses from circularity, polarization, sidelobes, blah blah, 10^9 is a BILLION times advantage for your signal to clobber the Galileo signal before you take these into account. This calculation does not include any shaping of the beam on your part so a few dB gain in the direction of the ground station and the problem is worse. As the airplane approaches your location from 100 km, you will overload the front end without drastic measures taken by the manufacturers.
Please understand the engineers designing the Galileo system understand these issues well. They will argue very strongly that the interference sources be removed since they do not wish to notch you by 90 dB!
Bob N4HY
John B. Stephensen wrote:
The article predicts that there may be limitations on the amateur service. The biggest problem is sidelobes from the antenna that can be of either polarization sense. A 16 kW EIRP uplink can easily generate 500 W EIRP sidelobes (15 dB down) within the Galileo receiver passband and,
replicating
the calculations outlined in the article, they can cause interference from 42 km away.
73,
John KD6OZH
----- Original Message ----- From: "Marc Franco" lu6dw@yahoo.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 19:03 UTC Subject: [amsat-bb] Galileo interference on L band
John,
Galileo is circularly polarized, so using the opposite polarization sense will help.
An excellent paper on Galileo interference was written by Peter Blair, G3LTF, a well known moonbounce authority and outstanding engineer. The paper can be found following this link:
http://www.southgatearc.org/articles/galileo.htm
73, Marc N2UO
--- "John B. Stephensen" kd6ozh@comcast.net wrote:
Unfortunately, the Gaileo downlink covers 1258-1299 MHz, the first satellite has been lanched and the satellites in the constellation will be on over the entire world. Our uplink antennas have sidelobes that are 10-20 dB down, so a 1 kW EIRP SSB uplink results in 10-100 W radiated towards terrestrial receivers. A 256 kbps uplink would require 16 kW EIRP and be 0.5-1 MHz wide.
P3E has a second L receiver tuned to a null in the Galileo signal (there is only one null in the 1260-1270 MHz band) but no one knows if this will help. SSB users can move to the U uplink if L is a problem. However, this only works for narrowband signals. A wideband uplink won't fit in the null and can't move down in frequency.
73,
John KD6OZH
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-- Robert W. McGwier, Ph.D. Center for Communications Research 805 Bunn Drive Princeton, NJ 08540 (609)-924-4600 (sig required by employer)
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Friends,
My job deals with Air Traffic Control systems (I'm not a controller... I am an engineer for a company that makes all sorts of ATC electronics systems). You can be assured that neither the FAA nor Eurocontrol (the European version of FAA) will require any navigation or landing system without years of testing. And re-testing. And more testing after that. GPS has been under study for at least 10 years... Galileo will receive the same scrutiny when it is operational. That means that adoption of any GPS +/- Galileo system for precision air navigation or landing is a LONG way off.
Having said this, AMSAT planners should know that any amateur interference or intrusion into the GPS & Galileo "band" would be supremely foolish. All the arguments about how ham radio is great in emergencies will count for nothing the first time an aircraft crashes after losing its satellite navigation due to interference. I have been a ham for 35+ years and love the hobby dearly, but we must keep in mind that in the Big Picture, we are not very important. The FCC and its European counterparts will yank our 13cm ("L" band) allocation in a heartbeat if we interfere with GPS/Galileo.
73, W9IP
On 20 Sep 2006 at 17:51, Michael R. Owen wrote:
All the arguments about how ham radio is great in emergencies will count for nothing the first time an aircraft crashes after losing its satellite navigation due to interference. I have been a ham for 35+ years and love the hobby dearly, but we must keep in mind that in the Big Picture, we are not very important. > 73, W9IP
-- Michael R. Owen, W9IP
It is refreshing to see wisdom is still present in the Ham community. If AMSAT-NA is willing to buy some i will try to be the first seller.
Who wants to be a millionnaire!
Not all hope is gone yet "Don't forget, these issues are all under review as we speak."
Written by: Rick W2GPS
P.S. Always impress by call sign letter choices...
"-" The medium is the message...The content is the audience...;)
Luc Leblanc VE2DWE WAC basic,CW,Phone,Satellite Skype VE2DWE www.qsl.net/ve2dwe
Gosh! How did we ever fly airplanes without crashing them, before satellite navigation?
Show me a commercial pilot who would rely solely on his GPS for navigation, and I'll show you a pilot who doesn't belong in the cockpit!
----- Original Message ----- From: "Michael R. Owen" nlsa@nlsa.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 4:51 PM Subject: [amsat-bb] Re: Galileo interference on L band
Friends,
<snip>
Having said this, AMSAT planners should know that any amateur interference or intrusion into the GPS & Galileo "band" would be supremely foolish. All the arguments about how ham radio is great in emergencies will count for nothing the first time an aircraft crashes after losing its satellite navigation due to interference. I have been a ham for 35+ years and love the hobby dearly, but we must keep in mind that in the Big Picture, we are not very important. The FCC and its European counterparts will yank our 13cm ("L" band) allocation in a heartbeat if we interfere with GPS/Galileo.
73, W9IP
-- Michael R. Owen, W9IP
At 11:08 PM 9/20/2006, George Henry wrote:
Gosh! How did we ever fly airplanes without crashing them, before satellite navigation?
Show me a commercial pilot who would rely solely on his GPS for navigation, and I'll show you a pilot who doesn't belong in the cockpit!
With all due respect George, that is an overly emotional and inane comment. I relied on GPS navigation solely on my trip back from the DCC in Tucson ... as well, I used my XM-Radio weather datalink to pick my way through the front created by Hurricane Helene. The VOR receiver would not have allowed me to do all that.
And once my Garmin 430 is updated for WAAS , I'll be able to do precision approaches with GPS.
ADFs are being decommissioned and I doubt you'll see any new ILS approaches being installed ...
No, I'm not a COMMERCIAL pilot, but I fly a lot, and there ARE a lot of commercial missions being flown with GPS alone (with probably 2 GPS receivers on board). AND, GPS improves situational awareness which DOES decrease crashes and other accidents.
73 Dave VE3GYQ/W8 Spencerville, OH
Do not forget that GPS will be a key component of ADS-B, which has been accepted by the FAA.
John WA4WDL
----- Original Message ----- From: "David B. Toth" ve3gyq@amsat.org To: "George Henry" ka3hsw@earthlink.net; "amsat bb" amsat-bb@amsat.org Sent: Thursday, September 21, 2006 12:28 AM Subject: [amsat-bb] Re: Galileo interference on L band
At 11:08 PM 9/20/2006, George Henry wrote:
Gosh! How did we ever fly airplanes without crashing them, before satellite navigation?
Show me a commercial pilot who would rely solely on his GPS for navigation, and I'll show you a pilot who doesn't belong in the cockpit!
With all due respect George, that is an overly emotional and inane comment. I relied on GPS navigation solely on my trip back from the DCC in Tucson ... as well, I used my XM-Radio weather datalink to pick my way through the front created by Hurricane Helene. The VOR receiver would not have allowed me to do all that.
And once my Garmin 430 is updated for WAAS , I'll be able to do precision approaches with GPS.
ADFs are being decommissioned and I doubt you'll see any new ILS approaches being installed ...
No, I'm not a COMMERCIAL pilot, but I fly a lot, and there ARE a lot of commercial missions being flown with GPS alone (with probably 2 GPS receivers on board). AND, GPS improves situational awareness which DOES decrease crashes and other accidents.
73 Dave VE3GYQ/W8 Spencerville, OH
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My point is that no pilot should put all his eggs in one basket, nor does any autopilot system rely on one source of data, such as GPS. There are also data that GPS simply cannot provide (like height above terrain). GPS is not now, nor do I think it ever will be, the "be-all and end-all" for aeronautical navigation. There will ALWAYS be backup systems to GPS, primary systems to which GPS might be the backup, and systems which GPS cannot replace.
This is probably all moot, as others have pointed out that the Galileo web site makes it clear that the aviation and other "safety of life" services will be on channels well-removed from our allocations.
----- Original Message ----- From: "David B. Toth" ve3gyq@amsat.org To: "George Henry" ka3hsw@earthlink.net; "amsat bb" amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 11:28 PM Subject: Re: [amsat-bb] Re: Galileo interference on L band
At 11:08 PM 9/20/2006, George Henry wrote:
Gosh! How did we ever fly airplanes without crashing them, before satellite navigation?
Show me a commercial pilot who would rely solely on his GPS for navigation, and I'll show you a pilot who doesn't belong in the cockpit!
With all due respect George, that is an overly emotional and inane comment. I relied on GPS navigation solely on my trip back from the DCC in Tucson ... as well, I used my XM-Radio weather datalink to pick my way through the front created by Hurricane Helene. The VOR receiver would not have allowed me to do all that.
And once my Garmin 430 is updated for WAAS , I'll be able to do precision approaches with GPS.
ADFs are being decommissioned and I doubt you'll see any new ILS approaches being installed ...
No, I'm not a COMMERCIAL pilot, but I fly a lot, and there ARE a lot of commercial missions being flown with GPS alone (with probably 2 GPS receivers on board). AND, GPS improves situational awareness which DOES decrease crashes and other accidents.
73 Dave VE3GYQ/W8 Spencerville, OH
Right on. Every airplane flying passengers will still have our GPS system on board. The european gps if it ever is built will broadcast on three (3) channels so even if one was degraded a little bit it wouldn't matter much. They will need to keep our system if they ever want to be able to fly passengers into US or NATO controlled airspace. It will be at least 10-15 years before such a system could be in place and certified by the airlines. By then Eagle would be at the end of its life anyway.
If we just give up whole freq bands because we are scared of the big bad europeans who are drowning in socialist social program debt, then we deserve to lose our bands if we give up without a fight. If a country tries to take away our bad because of this "bad science" then we should fight them in court and in the public relations area. I say figure out a way to use and justify our L band in WWIII that we find ourselves in now. Are we not now recognized at least in this country as the last line of communications in case of attack? Plan for a way to use Eagle when the next attack or hurricane comes our way.
If L band makes sense from a technical point of view then build and deploy it. let the political battles come and be fought if they must after that.
Les W4SCO
At 11:08 PM 9/20/2006, George Henry wrote:
Gosh! How did we ever fly airplanes without crashing them, before satellite navigation?
Show me a commercial pilot who would rely solely on his GPS for navigation, and I'll show you a pilot who doesn't belong in the cockpit!
----- Original Message ----- From: "Michael R. Owen" nlsa@nlsa.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 4:51 PM Subject: [amsat-bb] Re: Galileo interference on L band
Friends,
<snip> > > Having said this, AMSAT planners should know that any amateur > interference or intrusion into the GPS & Galileo "band" would be > supremely foolish. All the arguments about how ham radio is great in > emergencies will count for nothing the first time an aircraft crashes > after losing its satellite navigation due to interference. I have been > a ham for 35+ years and love the hobby dearly, but we must keep in mind > that in the Big Picture, we are not very important. The FCC and its > European counterparts will yank our 13cm ("L" band) allocation in a > heartbeat if we interfere with GPS/Galileo. > > 73, > W9IP > > -- > Michael R. Owen, W9IP >
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The first HEO U/V linear transponder flew in 1983 and everyone wants compatibility for the next satellite -- effectively until 2018. A digital transponder will have the same issues. If the first one flies in 2010, users will want compatibility until 2045.
73,
John KD6OZH
----- Original Message ----- From: sco@sco-inc.com To: "amsat bb" amsat-bb@amsat.org Sent: Thursday, September 21, 2006 04:54 UTC Subject: [amsat-bb] Re: Galileo interference on L band
Right on. Every airplane flying passengers will still have our GPS system on board. The european gps if it ever is built will broadcast on three (3) channels so even if one was degraded a little bit it wouldn't matter much. They will need to keep our system if they ever want to be able to fly passengers into US or NATO controlled airspace. It will be at least 10-15 years before such a system could be in place and certified by the airlines. By then Eagle would be at the end of its life anyway.
If we just give up whole freq bands because we are scared of the big bad europeans who are drowning in socialist social program debt, then we deserve to lose our bands if we give up without a fight. If a country tries to take away our bad because of this "bad science" then we should fight them in court and in the public relations area. I say figure out a way to use and justify our L band in WWIII that we find ourselves in now. Are we not now recognized at least in this country as the last line of communications in case of attack? Plan for a way to use Eagle when the next attack or hurricane comes our way.
If L band makes sense from a technical point of view then build and deploy it. let the political battles come and be fought if they must after that.
Les W4SCO
At 11:08 PM 9/20/2006, George Henry wrote:
Gosh! How did we ever fly airplanes without crashing them, before satellite navigation?
Show me a commercial pilot who would rely solely on his GPS for navigation, and I'll show you a pilot who doesn't belong in the cockpit!
----- Original Message ----- From: "Michael R. Owen" nlsa@nlsa.com To: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 4:51 PM Subject: [amsat-bb] Re: Galileo interference on L band
Friends,
<snip> > > Having said this, AMSAT planners should know that any amateur > interference or intrusion into the GPS & Galileo "band" would be > supremely foolish. All the arguments about how ham radio is great in > emergencies will count for nothing the first time an aircraft crashes > after losing its satellite navigation due to interference. I have been > a ham for 35+ years and love the hobby dearly, but we must keep in mind > that in the Big Picture, we are not very important. The FCC and its > European counterparts will yank our 13cm ("L" band) allocation in a > heartbeat if we interfere with GPS/Galileo. > > 73, > W9IP > > -- > Michael R. Owen, W9IP >
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
Les,
Galileo (if it is ever built and launched and worked) would just be over Europe, right?
No.
That would leave the rest of the world the ability to use our L band uplink, right?
No.
If we hams are using a dish pointed at the sky with a narrow bandwidth how is that going to interfere with ground receivers some distance from us?
The high EIRP signals will impinge on aircraft. Also, other Hams like ATV will create interference that will not be tolerated for long and all will suffer the consequences.
We would be smart enough to not have the Eagle uplink on the same freq, right?
Wrong, there is almost no place to hide.
And we would design Eagle such that we could (from ground control) move the Eagle receive freq away from any potential conflict with Galileo, right?
No.
And Eagle would be in orbit and operational long before Galileo, right?
No.
And Galileo receivers on the ground will have the ability to cut out any possible interference from us, right?
No.
Seems to me that we are planning to give up the L band (as an uplink) based on a lot of bad assumptions.
The assumption that we are giving up on anything, including L-band, for our satellites (P3E and Eagle) is overblown and untrue.
Rick W2GPS AMSAT LM2232
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of sco@sco-inc.com Sent: Wednesday, September 20, 2006 12:16 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: Why do the amsats get more and more complex?
Galileo (if it is ever built and launched and worked) would just be over Europe, right? That would leave the rest of the world the ability to use our L band uplink, right? If we hams are using a dish pointed at the sky with a narrow bandwidth how is that going to interfere with ground receivers some distance from us? We would be smart enough to not have the Eagle uplink on the same freq, right? And we would design Eagle such that we could (from ground control) move the Eagle receive freq away from any potential conflict with Galileo, right? And Eagle would be in orbit and operational long before Galileo, right? And Galileo receivers on the ground will have the ability to cut out any possible interference from us, right?
Seems to me that we are planning to give up the L band (as an uplink) based on a lot of bad assumptions.
Les W4SCO
The answer is in two parts. First, an L-band ground antenna would be too large to disguise as a TVRO dish. Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers.
I don't wish to debate these points. I'm just telling you the reasoning
that
went into not choosing L-band. I assure you that every possibility was considered. Lists were created and discussed on each alternative.
Rick W2GPS AMSAT LM2232
_______________________________________________ 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 Rick,
I've been critical of the "no L-Band" decision and your recent comments don't lessen that critique.
Your last posting said "Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers."
What concrete evidence is available that substantiates your claim? Perhaps "real" data could convince me and others that the decision is based on fact and not a paranoia about what could happen. Everything I've heard to date from AMSAT is anecdotal, opinionated and based on what you just said - FEAR.
To the contrary, the "fact" is that Galileo's own web site states (which I have referenced here already) the reality of having to work in an interference environment (i.e. ground ATC radar's and harmonics from TV transmitters just to name of few) and has already started a two year study program to evaluate appropriate design considerations.
I have been unable to find ANY reference to any governmental agency making plans to eliminate the L-Band Amateur allocation in view of Galileo. Do you have evidence to the contrary?
Another "fact" is that the P3E team, rather than "abandoning" the allocation, has an "engineering" approach to mitigate the potential for interference by selecting a L-Band frequency which puts the signal in a Galileo signal null (already pointed out by others here).
This debate could be put to rest if you could present us with "facts" and not the "lets get out of the kitchen 'cause we may not be able to stand the heat" argument I've seen so far.
Ready to be convinced...
Bill - N6GHz AMSAT #21049
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org]On Behalf Of Rick Hambly (W2GPS) Sent: Wednesday, September 20, 2006 5:55 AM To: sco@sco-inc.com Cc: amsat-bb@amsat.org Subject: [amsat-bb] Re: Why do the amsats get more and more complex?
Les,
Don't forget, these issues are all under review as we speak.
The answer is in two parts. First, an L-band ground antenna would be too large to disguise as a TVRO dish. Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers.
I don't wish to debate these points. I'm just telling you the reasoning that went into not choosing L-band. I assure you that every possibility was considered. Lists were created and discussed on each alternative.
Rick W2GPS AMSAT LM2232
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Bill Ress wrote:
Hi Rick,
I've been critical of the "no L-Band" decision and your recent comments don't lessen that critique.
Your last posting said "Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers."
What concrete evidence is available that substantiates your claim? Perhaps "real" data could convince me and others that the decision is based on fact and not a paranoia about what could happen. Everything I've heard to date from AMSAT is anecdotal, opinionated and based on what you just said - FEAR.
What will happen if the Galileo goes up is that no European airport will allow a commercial jetliner to land without the Galileo system. This will inevitably lead to this basic system being in world wide use for navigational purposes. The Near/Far difference between your emission of billions of times as much power (so far as the aircraft receiver is concerned) as that to be received by the aircraft from the satellite will inevitably lead to collapse of the front end. The receiver manufacturers will not want to build high quality, expensive front ends to filter out powerful emissions that could bring an airplane down. They will choose the path of "clean the bums out" and they will win. The Europeans no longer wish to maintain the VOR sites and their contention is that Galileo will be less expensive in the long run. There are indeed some who argue the upfront cost will be too large for the Europeans to actually come up with but until they announce this one must assume they will go forward.
So your idea is that we should spend $10,000,000 of donated money on the back of prayer that Galileo will not force us off our band when we KNOW it will be viewed as a safety of life service and that we will overload the front ends of the receiver in the (admittedly very rare) cases where the airplanes are in our emitter beams? No one can be that naive to believe that even the slightest possibility of interference will be allowed.
To the contrary, the "fact" is that Galileo's own web site states (which I have referenced here already) the reality of having to work in an interference environment (i.e. ground ATC radar's and harmonics from TV transmitters just to name of few) and has already started a two year study program to evaluate appropriate design considerations.
We cannot use L band for the advanced communications package anyway because we do not want to increase the antenna size for the ground user. We want to accomodate CC&R restricted users with a 60cm (2 foot) dish. The L band feed required, being dual band with C band (say) makes this infeasible.
So the argument is whether or not to design an L band receiver for the linear transponder. I have asked John Stephensen to do just exactly that. I asked him to do this a few months ago and he has taken up the challenge. I don't understand what the argument is about.
I have been unable to find ANY reference to any governmental agency making plans to eliminate the L-Band Amateur allocation in view of Galileo. Do you have evidence to the contrary?
Another "fact" is that the P3E team, rather than "abandoning" the allocation, has an "engineering" approach to mitigate the potential for interference by selecting a L-Band frequency which puts the signal in a Galileo signal null (already pointed out by others here).
Here is a fact you have not taken into account. The advanced communications package needs 10 MHz not a few tens of kHz but I have already discussed why L band is not usable for the system (ground and space) we are attempting to accomodate. That has nothing to do with Galileo or the loss of L band. In fact, if we can fit the antennas on the spacecraft, I see no reason we shouldn't include an L band receiver and we should drop it into the Galileo null. The issue will be coordination with our AMSAT-DL friends and partners to mitigate interference issues. These should be rare indeed if we achieve our target orbit for Eagle and they achieve their target orbit for P3E. The birds will be many degrees apart almost always when L band will be appropriate.
This debate could be put to rest if you could present us with "facts" and not the "lets get out of the kitchen 'cause we may not be able to stand the heat" argument I've seen so far.
Ready to be convinced...
Bill - N6GHz AMSAT #21049
73's Bob N4HY
Bill,
I've already written a requirements document for the L receiver. It may end up being a U receiver (see EaglePedia for description and schematics) modified for different first LO and RF frequencies. It's a secondary uplink for the linear transponder, but can't be the primary uplink for the digital transponder.
73,
John KD6OZH
----- Original Message ----- From: "Bob McGwier" n4hy@idaccr.org To: "Bill Ress" bill@hsmicrowave.com Cc: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 18:21 UTC Subject: [amsat-bb] Re: Why do the amsats get more and more complex?
Bill Ress wrote:
Hi Rick,
I've been critical of the "no L-Band" decision and your recent comments don't lessen that critique.
Your last posting said "Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers."
What concrete evidence is available that substantiates your claim? Perhaps "real" data could convince me and others that the decision is based on fact and not a paranoia about what could happen. Everything I've heard to date from AMSAT is anecdotal, opinionated and based on what you just said - FEAR.
What will happen if the Galileo goes up is that no European airport will allow a commercial jetliner to land without the Galileo system. This will inevitably lead to this basic system being in world wide use for navigational purposes. The Near/Far difference between your emission of billions of times as much power (so far as the aircraft receiver is concerned) as that to be received by the aircraft from the satellite will inevitably lead to collapse of the front end. The receiver manufacturers will not want to build high quality, expensive front ends to filter out powerful emissions that could bring an airplane down. They will choose the path of "clean the bums out" and they will win. The Europeans no longer wish to maintain the VOR sites and their contention is that Galileo will be less expensive in the long run. There are indeed some who argue the upfront cost will be too large for the Europeans to actually come up with but until they announce this one must assume they will go forward.
So your idea is that we should spend $10,000,000 of donated money on the back of prayer that Galileo will not force us off our band when we KNOW it will be viewed as a safety of life service and that we will overload the front ends of the receiver in the (admittedly very rare) cases where the airplanes are in our emitter beams? No one can be that naive to believe that even the slightest possibility of interference will be allowed.
To the contrary, the "fact" is that Galileo's own web site states (which I have referenced here already) the reality of having to work in an interference environment (i.e. ground ATC radar's and harmonics from TV transmitters just to name of few) and has already started a two year study program to evaluate appropriate design considerations.
We cannot use L band for the advanced communications package anyway because we do not want to increase the antenna size for the ground user. We want to accomodate CC&R restricted users with a 60cm (2 foot) dish. The L band feed required, being dual band with C band (say) makes this infeasible.
So the argument is whether or not to design an L band receiver for the linear transponder. I have asked John Stephensen to do just exactly that. I asked him to do this a few months ago and he has taken up the challenge. I don't understand what the argument is about.
I have been unable to find ANY reference to any governmental agency making plans to eliminate the L-Band Amateur allocation in view of Galileo. Do you have evidence to the contrary?
Another "fact" is that the P3E team, rather than "abandoning" the allocation, has an "engineering" approach to mitigate the potential for interference by selecting a L-Band frequency which puts the signal in a Galileo signal null (already pointed out by others here).
Here is a fact you have not taken into account. The advanced communications package needs 10 MHz not a few tens of kHz but I have already discussed why L band is not usable for the system (ground and space) we are attempting to accomodate. That has nothing to do with Galileo or the loss of L band. In fact, if we can fit the antennas on the spacecraft, I see no reason we shouldn't include an L band receiver and we should drop it into the Galileo null. The issue will be coordination with our AMSAT-DL friends and partners to mitigate interference issues. These should be rare indeed if we achieve our target orbit for Eagle and they achieve their target orbit for P3E. The birds will be many degrees apart almost always when L band will be appropriate.
This debate could be put to rest if you could present us with "facts" and not the "lets get out of the kitchen 'cause we may not be able to stand the heat" argument I've seen so far.
Ready to be convinced...
Bill - N6GHz AMSAT #21049
73's Bob N4HY
-- Robert W. McGwier, Ph.D. Center for Communications Research 805 Bunn Drive Princeton, NJ 08540 (609)-924-4600 (sig required by employer)
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Hi Bob,
Thanks for your response which is starting to focus on the pitch you really need to make, and which you can defend (it's down toward the end!).
You state another "what if" and not a "fact."
"What will happen if the Galileo goes up is that no European airport will allow a commercial jetliner to land without the Galileo system. This will inevitably lead to this basic system being in world wide use for navigational purposes."
But consider the "fact" that all commercial airlines are currently using the US GPS system and a MLS (microwave landing system) that uses around 5 GHz. Our GPS system is also going through additional studies regarding issues with potential interference and these are NOT Amateur transmissions. Since the Galileo is intended to focus on "personal" and "for profit" applications, (check out their web site and mission statements), I can't see commercial airlines scraping their current working systems in favor of an uncertain Galileo system. If they do - it will be many, many years down the road. So I can't buy your commercial airline "fear" scenario. Again an argument based on "fear" not "fact".
Again, I keep repeating that Galileo recognizes the potential for interference (again - see their web site). We are but one of many potential sources of interference. In "fact" to date they have not even included us in their list of potential interfering sources (again see their web site).
You state "The receiver manufacturers will not want to build high quality, expensive front ends to filter out powerful emissions that could bring an airplane down. They will choose the path of "clean the bums out" and they will win."
You can't be serious Bob? You know darn well any airborne receiver used for aircraft navigation will be designed to be as bullet proof as possible. Again read the Galileo web site for their comments about interference where they state their system will "detect, identify and mitigate" potential inference. Is this lip service to sell the system or a real desire to build a solid system?
You state:
"So your idea is that we should spend $10,000,000 of donated money on the back of prayer that Galileo will not force us off our band when we KNOW it will be viewed as a safety of life service and that we will overload the front ends of the receiver in the (admittedly very rare) cases where the airplanes are in our emitter beams? No one can be that naive to believe that even the slightest possibility of interference will be allowed."
No Bob, I'm saying that your reason for dropping L-Band should be based on technical considerations not "fear" of what might happen.
You state:
"We cannot use L band for the advanced communications package anyway because we do not want to increase the antenna size for the ground user. We want to accomodate CC&R restricted users with a 60cm (2 foot) dish. The L band feed required, being dual band with C band (say) makes this infeasible."
Bob - now you talking the RIGHT ARGUMENT! Given a variety of technical considerations, available money, available current, space etc., these are the justifications you need to emphasize.
Get this "weak" (in my opinion) Galileo argument off the table and focus on we what we know to be the "real science" that you are already bringing to the project.
You stated another good technical "fact" when you said:
"Here is a fact you have not taken into account. The advanced communications package needs 10 MHz not a few tens of kHz but I have already discussed why L band is not usable for the system (ground and space) we are attempting to accomodate. That has nothing to do with Galileo or the loss of L band. In fact, if we can fit the antennas on the spacecraft, I see no reason we shouldn't include an L band receiver and we should drop it into the Galileo null. The issue will be coordination with our AMSAT-DL friends and partners to mitigate interference issues. These should be rare indeed if we achieve our target orbit for Eagle and they achieve their target orbit for P3E. The birds will be many degrees apart almost always when L band will be appropriate."
Way to go Bob. Technical arguments! That's what I want and your hitting on them now.
Bill - N6GHz AMSAT #21049
----- Original Message ----- From: "Bob McGwier" n4hy@idaccr.org To: "Bill Ress" bill@hsmicrowave.com Cc: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 8:21 PM Subject: [amsat-bb] Re: Why do the amsats get more and more complex?
Hi Bob, N4HY
You said"
What will happen if the Galileo goes up is that no European airport will allow a commercial jetliner to land without the Galileo system. This will inevitably lead to this basic system being in world wide use for navigational purposes.
Does this imply that all 23 cm EME stations have to be moved away from 1296 MHz ?
73's Bob N4HY
73" de
i8CVS Domenico
Dom:
I do not have a crystal ball and I would not presume to say that I know the ultimate outcome. I can only say what I believe. I believe strongly that if Galileo goes up and the safety of life services we envision are made mandatory for airplanes in the EU, that amateur radio operators in Europe in particular will lose all of L band. I believe this because the manufacturers will not want to have to provide highly selective front ends that will reduce the near/far problem to manageable levels. There are simple laws of physics that dictate the nature, size, etc. to get these filters to operate with the required Q that will allow us to continue to aim thousand of watts into high gain antennas and point them up. Possibly the aviation control bodies such as our FAA will force them to include them. But the manufacturers will not do it willingly when only a few hams are in the way of a multi-billion dollar industry.
Again, for the record, these are my opinions based on an understanding of what it will take to make them immune to interference from us.
73's Bob N4HY
i8cvs wrote:
----- Original Message ----- From: "Bob McGwier" n4hy@idaccr.org To: "Bill Ress" bill@hsmicrowave.com Cc: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 8:21 PM Subject: [amsat-bb] Re: Why do the amsats get more and more complex?
Hi Bob, N4HY
You said"
What will happen if the Galileo goes up is that no European airport will allow a commercial jetliner to land without the Galileo system. This will inevitably lead to this basic system being in world wide use for navigational purposes.
Does this imply that all 23 cm EME stations have to be moved away from 1296 MHz ?
73's Bob N4HY
73" de
i8CVS Domenico
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At 06:04 AM 9/21/2006 +0200, i8cvs wrote:
----- Original Message ----- From: "Bob McGwier" n4hy@idaccr.org To: "Bill Ress" bill@hsmicrowave.com Cc: amsat-bb@amsat.org Sent: Wednesday, September 20, 2006 8:21 PM Subject: [amsat-bb] Re: Why do the amsats get more and more complex?
Hi Bob, N4HY
You said"
What will happen if the Galileo goes up is that no European airport will allow a commercial jetliner to land without the Galileo system. This will inevitably lead to this basic system being in world wide use for navigational purposes.
Does this imply that all 23 cm EME stations have to be moved away from 1296 MHz ?
73's Bob N4HY
73" de
i8CVS Domenico
Domenico and other interested folks,
Read what G3LTF has said about Galileo and 23cm EME: http://www.batc.org.uk/club_stuff/G3LTF_Galileo.pdf
He paints not quite so bad a picture as Bob and John do. If you think a handful of "potential" ham satellite users are potentially effected, the large (2nd most popular EME band, today) 23cm EME population are watching this keenly. I have several thousand dollars invested in my future 23cm EME station...and I will just been a medium size station. There several
10m EME dishes operating in Europe...those are not cheap. I suspect Ham
radio on L-band will not go down without controversy and a significant fight. Yes, I understand the multi-B$ industry "owns" the radio spectrum, but I think this is gotten a bit hysterical and negative in view. I suspect EME will survive on 23cm and perhaps satellite uplink use (with some compromise).
At this point it is all speculation (even with engineering analysis). I am glad the decision is to fly a mode-L Rx. I predict it will be usable in the early years of Eagle (at least). 73's, Ed - KL7UW ========================================= http://www.qsl.net/al7eb - BP40iq 144-EME: FT-847, mgf-1801/1402, 4xM2-xpol-20, 170w 432-EME: FT-847, mgf-1402, 1x21-ele (18.6 dBi), 60w =========================================
Bill,
Your premise that there is no L-band is incorrect and based on fragments of comments, not the whole story. The Eagle satellite is still undergoing design review but I suspect you will fine L-band to be active in the final design. If you want to be part of the discussions, join the Eagle project team and contribute your time and energy to the satellite design as many others are doing. That, and not amsat-bb is where the serious technical discussions are taking place.
Rick W2GPS AMSAT LM2232
-----Original Message----- From: Bill Ress [mailto:bill@hsmicrowave.com] Sent: Wednesday, September 20, 2006 1:15 PM To: Rick Hambly (W2GPS); sco@sco-inc.com Cc: amsat-bb@amsat.org Subject: RE: [amsat-bb] Re: Why do the amsats get more and more complex?
Hi Rick,
I've been critical of the "no L-Band" decision and your recent comments don't lessen that critique.
Your last posting said "Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers."
What concrete evidence is available that substantiates your claim? Perhaps "real" data could convince me and others that the decision is based on fact and not a paranoia about what could happen. Everything I've heard to date from AMSAT is anecdotal, opinionated and based on what you just said - FEAR.
To the contrary, the "fact" is that Galileo's own web site states (which I have referenced here already) the reality of having to work in an interference environment (i.e. ground ATC radar's and harmonics from TV transmitters just to name of few) and has already started a two year study program to evaluate appropriate design considerations.
I have been unable to find ANY reference to any governmental agency making plans to eliminate the L-Band Amateur allocation in view of Galileo. Do you have evidence to the contrary?
Another "fact" is that the P3E team, rather than "abandoning" the allocation, has an "engineering" approach to mitigate the potential for interference by selecting a L-Band frequency which puts the signal in a Galileo signal null (already pointed out by others here).
This debate could be put to rest if you could present us with "facts" and not the "lets get out of the kitchen 'cause we may not be able to stand the heat" argument I've seen so far.
Ready to be convinced...
Bill - N6GHz AMSAT #21049
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org]On Behalf Of Rick Hambly (W2GPS) Sent: Wednesday, September 20, 2006 5:55 AM To: sco@sco-inc.com Cc: amsat-bb@amsat.org Subject: [amsat-bb] Re: Why do the amsats get more and more complex?
Les,
Don't forget, these issues are all under review as we speak.
The answer is in two parts. First, an L-band ground antenna would be too large to disguise as a TVRO dish. Second, there is fear that over the lifetime of Eagle that L-band could become unavailable, particularly in Europe, if the Galileo system is deployed. Galileo would be a primary service and Ham transmissions would likely interfere with low cost commercial receivers.
I don't wish to debate these points. I'm just telling you the reasoning that went into not choosing L-band. I assure you that every possibility was considered. Lists were created and discussed on each alternative.
Rick W2GPS AMSAT LM2232
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (18)
-
Bill Ress -
Bob McGwier -
Bruce Rahn -
David B. Toth -
Edward R. Cole -
George Henry -
Greg D. -
i8cvs -
jmfranke -
John B. Stephensen -
Luc Leblanc VE2DWE -
Marc Franco -
Michael R. Owen -
Rick Hambly (W2GPS) -
Robert Bruninga -
Robert McGwier -
sco＠sco-inc.com -
Trevor