In the time since the San Diego meeting, I have come to realize that:
1 - Nothing is ever final.
2 - The decision about bands for the DCP (digital communications payload) is likely to be made in some combination of the following venues, in none of which you are likely to find me: A - AMSAT-BB B - AMSAT Board Meetings C - Meetings with shadowy DoD figures without names D - IARU, ITU, ARRL, QCWA, or Wuoff-Hong Society meetings
3 - Many of the decision makers (especially those speaking the loudest) think that SSB is the way of the future and Shannon's Law means that sex offenders have to register with the police.
4 - It really doesn't matter to me which bands are chosen, as long as they meet certain basic criteria.
In that spirit, I decided to distill the major technical constraints which we agreed on at the San Diego meeting, in order to give a basic set of rules which would provide us a workable bandplan for this satellite. The only legal/regulatory constraint I applied to this list is that we are unlikely to GAIN privileges. Someone else can decide how likely we are to lose them.
The constraints, and their reasons, as I see the consensus from the SD meeting:
1 - The uplink band must be chosen from the set of { L, S1, S2, C }. The lower bands simply don't have the bandwidth necessary for what we want to do, and would have unwieldy antennas. The higher bands are much more difficult due to the pointing accuracy required for antennas and the difficulty of generating significant power and low noise figures.
2 - The downlink band must be chose from the set of { S1, S2, C }. The same reasons as constraint #1, with the added constraint that L-band is not legal for downlink (which falls under the "we're not likely to GAIN privileges" category).
3 - The uplink and downlink bands must be distinct. This means no C-C or S1-S1. The bands are simply too narrow to allow for practical duplexers in the quantity we are talking about (~36).
4 - The uplink band must not be used by any other payload on Eagle as a downlink. Obvious interference issues.
5 - The downlink band should not be used by any other payload as an uplink. Obvious interference issues.
6 - Sharing of uplink bands or downlink bands MAY be possible, but probably isn't necessary.
Taking constraints 1-6 together, the choices are (in the form A/B where A is up, B is down): { L/S1, L/S2, L/C, S1/S2, S1/C, S2/S1, S2/C, C/S1, C/S2 }
In addition to the above "hard facts", we can add in the following concerns which were expressed at the meeting:
7 - We would prefer not to use S1 as a downlink because of possible interference from WiFi devices. 8 - Fear of L being taken away 9 - Uncertain legality of S2 in ITU Region 1
This leads to the following matrix, which I believe effectively boils down the decision process from the SD meeting:
Bandplan 7 8 9 L/S1 X X L/S2 X X L/C X S1/S2 X S1/C S2/S1 X X S2/C X C/S1 X C/S2 X
The only bandplan with no X's is S1/C, which is what we chose at the meeting. Obviously, there are now additional concerns which have been raised: - S1-Uplink being taken away - #8 not being as big a deal as we thought.
This would change the matrix.
I welcome your thoughts, especially if you feel I have misrepresented the SD meeting consensus.
Thanks, Matt, N2MJI
Matt: I think you have done a nice job of condensing what we discussed there, or at least what I heard and captured in my notes.
Well done.
73, Jim [email protected]
Matt Ettus wrote:
In the time since the San Diego meeting, I have come to realize that:
1 - Nothing is ever final.
2 - The decision about bands for the DCP (digital communications payload) is likely to be made in some combination of the following venues, in none of which you are likely to find me: A - AMSAT-BB B - AMSAT Board Meetings C - Meetings with shadowy DoD figures without names D - IARU, ITU, ARRL, QCWA, or Wuoff-Hong Society meetings
3 - Many of the decision makers (especially those speaking the loudest) think that SSB is the way of the future and Shannon's Law means that sex offenders have to register with the police.
4 - It really doesn't matter to me which bands are chosen, as long as they meet certain basic criteria.
In that spirit, I decided to distill the major technical constraints which we agreed on at the San Diego meeting, in order to give a basic set of rules which would provide us a workable bandplan for this satellite. The only legal/regulatory constraint I applied to this list is that we are unlikely to GAIN privileges. Someone else can decide how likely we are to lose them.
The constraints, and their reasons, as I see the consensus from the SD meeting:
1 - The uplink band must be chosen from the set of { L, S1, S2, C }. The lower bands simply don't have the bandwidth necessary for what we want to do, and would have unwieldy antennas. The higher bands are much more difficult due to the pointing accuracy required for antennas and the difficulty of generating significant power and low noise figures.
2 - The downlink band must be chose from the set of { S1, S2, C }. The same reasons as constraint #1, with the added constraint that L-band is not legal for downlink (which falls under the "we're not likely to GAIN privileges" category).
3 - The uplink and downlink bands must be distinct. This means no C-C or S1-S1. The bands are simply too narrow to allow for practical duplexers in the quantity we are talking about (~36).
4 - The uplink band must not be used by any other payload on Eagle as a downlink. Obvious interference issues.
5 - The downlink band should not be used by any other payload as an uplink. Obvious interference issues.
6 - Sharing of uplink bands or downlink bands MAY be possible, but probably isn't necessary.
Taking constraints 1-6 together, the choices are (in the form A/B where A is up, B is down): { L/S1, L/S2, L/C, S1/S2, S1/C, S2/S1, S2/C, C/S1, C/S2 }
In addition to the above "hard facts", we can add in the following concerns which were expressed at the meeting:
7 - We would prefer not to use S1 as a downlink because of possible interference from WiFi devices. 8 - Fear of L being taken away 9 - Uncertain legality of S2 in ITU Region 1
This leads to the following matrix, which I believe effectively boils down the decision process from the SD meeting:
Bandplan 7 8 9 L/S1 X X L/S2 X X L/C X S1/S2 X S1/C S2/S1 X X S2/C X C/S1 X C/S2 X
The only bandplan with no X's is S1/C, which is what we chose at the meeting. Obviously, there are now additional concerns which have been raised:
- S1-Uplink being taken away
- #8 not being as big a deal as we thought.
This would change the matrix.
I welcome your thoughts, especially if you feel I have misrepresented the SD meeting consensus.
Thanks, Matt, N2MJI
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
Consideration of X-band was dropped early in the meeting, but should be part of the re-evaluation as a downlink band. I suspect that S2 is not viable as an uplink or downlink because of regulatory issues outside our region. If S1 is unavailable and L remains a potential problem, C/X is a possible solution. The proposal in the U.K. to sell 10.125-10.225 and 10.475-10.575 GHz still leaves 10.450-10.475 GHz available for amateur satellites.
73,
John KD6OZH
----- Original Message ----- From: "Jim Sanford" [email protected] To: "Matt Ettus" [email protected] Cc: "EAGLE" [email protected] Sent: Sunday, September 10, 2006 23:53 UTC Subject: [eagle] Re: DCP Bands
Matt: I think you have done a nice job of condensing what we discussed there, or at least what I heard and captured in my notes.
Well done.
73, Jim [email protected]
Matt Ettus wrote:
In the time since the San Diego meeting, I have come to realize that:
1 - Nothing is ever final.
2 - The decision about bands for the DCP (digital communications payload) is likely to be made in some combination of the following venues, in none of which you are likely to find me: A - AMSAT-BB B - AMSAT Board Meetings C - Meetings with shadowy DoD figures without names D - IARU, ITU, ARRL, QCWA, or Wuoff-Hong Society meetings
3 - Many of the decision makers (especially those speaking the loudest) think that SSB is the way of the future and Shannon's Law means that sex offenders have to register with the police.
4 - It really doesn't matter to me which bands are chosen, as long as they meet certain basic criteria.
In that spirit, I decided to distill the major technical constraints which we agreed on at the San Diego meeting, in order to give a basic set of rules which would provide us a workable bandplan for this satellite. The only legal/regulatory constraint I applied to this list is that we are unlikely to GAIN privileges. Someone else can decide how likely we are to lose them.
The constraints, and their reasons, as I see the consensus from the SD meeting:
1 - The uplink band must be chosen from the set of { L, S1, S2, C }. The lower bands simply don't have the bandwidth necessary for what we want to do, and would have unwieldy antennas. The higher bands are much more difficult due to the pointing accuracy required for antennas and the difficulty of generating significant power and low noise figures.
2 - The downlink band must be chose from the set of { S1, S2, C }. The same reasons as constraint #1, with the added constraint that L-band is not legal for downlink (which falls under the "we're not likely to GAIN privileges" category).
3 - The uplink and downlink bands must be distinct. This means no C-C or S1-S1. The bands are simply too narrow to allow for practical duplexers in the quantity we are talking about (~36).
4 - The uplink band must not be used by any other payload on Eagle as a downlink. Obvious interference issues.
5 - The downlink band should not be used by any other payload as an
uplink.
Obvious interference issues.
6 - Sharing of uplink bands or downlink bands MAY be possible, but probably isn't necessary.
Taking constraints 1-6 together, the choices are (in the form A/B where A is up, B is down): { L/S1, L/S2, L/C, S1/S2, S1/C, S2/S1, S2/C, C/S1, C/S2 }
In addition to the above "hard facts", we can add in the following concerns which were expressed at the meeting:
7 - We would prefer not to use S1 as a downlink because of possible interference from WiFi devices. 8 - Fear of L being taken away 9 - Uncertain legality of S2 in ITU Region 1
This leads to the following matrix, which I believe effectively boils down the decision process from the SD meeting:
Bandplan 7 8 9 L/S1 X X L/S2 X X L/C X S1/S2 X S1/C S2/S1 X X S2/C X C/S1 X C/S2 X
The only bandplan with no X's is S1/C, which is what we chose at the meeting. Obviously, there are now additional concerns which have been raised:
- S1-Uplink being taken away
- #8 not being as big a deal as we thought.
This would change the matrix.
I welcome your thoughts, especially if you feel I have misrepresented the SD meeting consensus.
Thanks, Matt, N2MJI
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
John B. Stephensen wrote:
Consideration of X-band was dropped early in the meeting, but should be part of the re-evaluation as a downlink band. I suspect that S2 is not viable as an uplink or downlink because of regulatory issues outside our region. If S1 is unavailable and L remains a potential problem, C/X is a possible solution. The proposal in the U.K. to sell 10.125-10.225 and 10.475-10.575 GHz still leaves 10.450-10.475 GHz available for amateur satellites.
I do not believe X-band is viable.
As we said at the meeting, links with both sides gain-limited will get worse at 6dB per octave. Links with both sides aperture-limited get better at 6dB per octave. Links with one side gain and one side aperture limited stay constant.
Remember, the satellite side of the link is gain-limited, so that means that for everything to stay the same, we'd have to keep the same apertures on the ground. A 60cm and 1.8m dish at 10 GHz are very tough to aim with simple setups. What is the pointing accuracy required for a 1.8m 10 GHz dish?
Matt
Pointing will be harder as the beamwidth decreases by 44%. I'd rather have an L-band uplink as its cheaper to generate RF for high data rate uplinks. However, its easier for us to solve engineering problems than regulatory problems.
Hams are using 12-foot TVRO dishes with COTS positioners for 10 GHz EME. When I lived in LA, I had a 2-foot dish for 10 GHz that was mounted on a Yaseu el-az rotator. It was difficult to point but it worked.
73,
John KD6OZH
----- Original Message ----- From: "Matt Ettus" [email protected] To: "John B. Stephensen" [email protected]; "EAGLE" [email protected] Sent: Monday, September 11, 2006 01:48 UTC Subject: Re: [eagle] Re: DCP Bands
John B. Stephensen wrote:
Consideration of X-band was dropped early in the meeting, but should be
part
of the re-evaluation as a downlink band. I suspect that S2 is not viable
as
an uplink or downlink because of regulatory issues outside our region. If
S1
is unavailable and L remains a potential problem, C/X is a possible solution. The proposal in the U.K. to sell 10.125-10.225 and
10.475-10.575
GHz still leaves 10.450-10.475 GHz available for amateur satellites.
I do not believe X-band is viable.
As we said at the meeting, links with both sides gain-limited will get worse at 6dB per octave. Links with both sides aperture-limited get better at 6dB per octave. Links with one side gain and one side aperture limited stay constant.
Remember, the satellite side of the link is gain-limited, so that means that for everything to stay the same, we'd have to keep the same apertures on the ground. A 60cm and 1.8m dish at 10 GHz are very tough to aim with simple setups. What is the pointing accuracy required for a 1.8m 10 GHz dish?
Matt
Thanks for sending this. I received no traffic from amsat.org between 9/8 at 4 AM and 4:57 AM this morning. Comcast had amsat.org blackballed.
I would not have known Matt sent this note without the inclusion.
It is just amazing to me what a land mine microwave has become. In the end, we are going to have to choose the best of no good options.
No one is frustrated with this more than me.
Bob
Jim Sanford wrote:
Matt: I think you have done a nice job of condensing what we discussed there, or at least what I heard and captured in my notes.
Well done.
73, Jim [email protected]
Matt Ettus wrote:
In the time since the San Diego meeting, I have come to realize that:
1 - Nothing is ever final.
2 - The decision about bands for the DCP (digital communications payload) is likely to be made in some combination of the following venues, in none of which you are likely to find me: A - AMSAT-BB B - AMSAT Board Meetings C - Meetings with shadowy DoD figures without names D - IARU, ITU, ARRL, QCWA, or Wuoff-Hong Society meetings
3 - Many of the decision makers (especially those speaking the loudest) think that SSB is the way of the future and Shannon's Law means that sex offenders have to register with the police.
4 - It really doesn't matter to me which bands are chosen, as long as they meet certain basic criteria.
In that spirit, I decided to distill the major technical constraints which we agreed on at the San Diego meeting, in order to give a basic set of rules which would provide us a workable bandplan for this satellite. The only legal/regulatory constraint I applied to this list is that we are unlikely to GAIN privileges. Someone else can decide how likely we are to lose them.
The constraints, and their reasons, as I see the consensus from the SD meeting:
1 - The uplink band must be chosen from the set of { L, S1, S2, C }. The lower bands simply don't have the bandwidth necessary for what we want to do, and would have unwieldy antennas. The higher bands are much more difficult due to the pointing accuracy required for antennas and the difficulty of generating significant power and low noise figures.
2 - The downlink band must be chose from the set of { S1, S2, C }. The same reasons as constraint #1, with the added constraint that L-band is not legal for downlink (which falls under the "we're not likely to GAIN privileges" category).
3 - The uplink and downlink bands must be distinct. This means no C-C or S1-S1. The bands are simply too narrow to allow for practical duplexers in the quantity we are talking about (~36).
4 - The uplink band must not be used by any other payload on Eagle as a downlink. Obvious interference issues.
5 - The downlink band should not be used by any other payload as an uplink. Obvious interference issues.
6 - Sharing of uplink bands or downlink bands MAY be possible, but probably isn't necessary.
Taking constraints 1-6 together, the choices are (in the form A/B where A is up, B is down): { L/S1, L/S2, L/C, S1/S2, S1/C, S2/S1, S2/C, C/S1, C/S2 }
In addition to the above "hard facts", we can add in the following concerns which were expressed at the meeting:
7 - We would prefer not to use S1 as a downlink because of possible interference from WiFi devices. 8 - Fear of L being taken away 9 - Uncertain legality of S2 in ITU Region 1
This leads to the following matrix, which I believe effectively boils down the decision process from the SD meeting:
Bandplan 7 8 9 L/S1 X X L/S2 X X L/C X S1/S2 X S1/C S2/S1 X X S2/C X C/S1 X C/S2 X
The only bandplan with no X's is S1/C, which is what we chose at the meeting. Obviously, there are now additional concerns which have been raised:
- S1-Uplink being taken away
- #8 not being as big a deal as we thought.
This would change the matrix.
I welcome your thoughts, especially if you feel I have misrepresented the SD meeting consensus.
Thanks, Matt, N2MJI
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
Eagle Team:
I concur with John's thought. I've been advocating consideration of X Band for some time. After all, we DID have it on AO-40, even if it was disabled by the unfortunate events which occurred to that handicapped bird.
One of the beefs about X Band have been the problem with getting low noise receivers, but low noise figure preamp devices are not that hard anymore. Just look at the results from the Central States noise figure tests and the fact that many people have low noise downconverters on their roofs.
Besides, ground station receivers won't be needed for several years yet and performance and prices should even more manageable by then.
So, let's at least put X Band into the mix for consideration.
CU in SF.
73,
Bill, W3XO
----- Original Message ----- From: "John B. Stephensen" [email protected] To: "Jim Sanford" [email protected]; "Matt Ettus" [email protected] Cc: "EAGLE" [email protected] Sent: Sunday, September 10, 2006 8:39 PM Subject: [eagle] Re: DCP Bands
Consideration of X-band was dropped early in the meeting, but should be part of the re-evaluation as a downlink band. I suspect that S2 is not viable as an uplink or downlink because of regulatory issues outside our region. If S1 is unavailable and L remains a potential problem, C/X is a possible solution. The proposal in the U.K. to sell 10.125-10.225 and 10.475-10.575 GHz still leaves 10.450-10.475 GHz available for amateur satellites.
73,
John KD6OZH
----- Original Message ----- From: "Jim Sanford" [email protected] To: "Matt Ettus" [email protected] Cc: "EAGLE" [email protected] Sent: Sunday, September 10, 2006 23:53 UTC Subject: [eagle] Re: DCP Bands
Matt: I think you have done a nice job of condensing what we discussed there, or at least what I heard and captured in my notes.
Well done.
73, Jim [email protected]
Matt Ettus wrote:
In the time since the San Diego meeting, I have come to realize that:
1 - Nothing is ever final.
2 - The decision about bands for the DCP (digital communications payload) is likely to be made in some combination of the following venues, in none of which you are likely to find me: A - AMSAT-BB B - AMSAT Board Meetings C - Meetings with shadowy DoD figures without names D - IARU, ITU, ARRL, QCWA, or Wuoff-Hong Society meetings
3 - Many of the decision makers (especially those speaking the loudest) think that SSB is the way of the future and Shannon's Law means that sex offenders have to register with the police.
4 - It really doesn't matter to me which bands are chosen, as long as they meet certain basic criteria.
In that spirit, I decided to distill the major technical constraints which we agreed on at the San Diego meeting, in order to give a basic set of rules which would provide us a workable bandplan for this satellite. The only legal/regulatory constraint I applied to this list is that we are unlikely to GAIN privileges. Someone else can decide how likely we are to lose them.
The constraints, and their reasons, as I see the consensus from the SD meeting:
1 - The uplink band must be chosen from the set of { L, S1, S2, C }. The lower bands simply don't have the bandwidth necessary for what we want to do, and would have unwieldy antennas. The higher bands are much more difficult due to the pointing accuracy required for antennas and the difficulty of generating significant power and low noise figures.
2 - The downlink band must be chose from the set of { S1, S2, C }. The same reasons as constraint #1, with the added constraint that L-band is not legal for downlink (which falls under the "we're not likely to GAIN privileges" category).
3 - The uplink and downlink bands must be distinct. This means no C-C or S1-S1. The bands are simply too narrow to allow for practical duplexers in the quantity we are talking about (~36).
4 - The uplink band must not be used by any other payload on Eagle as a downlink. Obvious interference issues.
5 - The downlink band should not be used by any other payload as an
uplink.
Obvious interference issues.
6 - Sharing of uplink bands or downlink bands MAY be possible, but probably isn't necessary.
Taking constraints 1-6 together, the choices are (in the form A/B where A is up, B is down): { L/S1, L/S2, L/C, S1/S2, S1/C, S2/S1, S2/C, C/S1, C/S2 }
In addition to the above "hard facts", we can add in the following concerns which were expressed at the meeting:
7 - We would prefer not to use S1 as a downlink because of possible interference from WiFi devices. 8 - Fear of L being taken away 9 - Uncertain legality of S2 in ITU Region 1
This leads to the following matrix, which I believe effectively boils down the decision process from the SD meeting:
Bandplan 7 8 9 L/S1 X X L/S2 X X L/C X S1/S2 X S1/C S2/S1 X X S2/C X C/S1 X C/S2 X
The only bandplan with no X's is S1/C, which is what we chose at the meeting. Obviously, there are now additional concerns which have been raised:
- S1-Uplink being taken away
- #8 not being as big a deal as we thought.
This would change the matrix.
I welcome your thoughts, especially if you feel I have misrepresented the SD meeting consensus.
Thanks, Matt, N2MJI
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
Via the Eagle mailing list courtesy of AMSAT-NA [email protected] http://amsat.org/mailman/listinfo/eagle
participants (5)
-
Bill Tynan -
Jim Sanford -
John B. Stephensen -
Matt Ettus -
Robert McGwier