Has Agrentina banned transmission on S1 for all amateur services -- terrestrial, earth and space stations?
Are we all still agreed that the primary analog and digital transponders must provide access over 75% of the orbit for ground stations using the minimum antenna/uplink power configuration?
73,
John KD6OZH
----- Original Message ----- From: "Robert McGwier" rwmcgwier@comcast.net To: "'EAGLE'" eagle@amsat.org Sent: Saturday, September 16, 2006 13:10 UTC Subject: [eagle] Re: C-C Rider Band Plan Follow-up
Outside of finding hard proof that S1 is unavailable in LU, I have not found another example and no one has emailed me their input saying anything to the contrary. I believe that we are going to have to do this study ourselves.
L is not a solution for the primary uplink for the DCP because of the CC&R antenna. I do not believe we can feed a conventional 60cm dish with a dual band feed that includes L. The aperture efficiency on C would drop too low to use even if we could get the L band feed to be usable. L and 2 foot dish aren't really compatible. I don't think even an offset feed will help. I will ask Tom and others to comment on the feasibility of this. I let this slip right past me when I was thinking about the alternatives. L would seem to require two separate antennas and I am loathe to go there.
It is irrelevant where the phase noise arises, on the spacecraft or on the ground. The convolution of all of the sources from the spacecraft transmitter through the receiver LO's and samplers on the ground will lead to a system cumulative noise rise due to oscillator phase noise irrespective of where the contribution arises. We might be able to overcome this on the spacecraft with more transmit power but then we have to figure out what to do with the extra heat . The heat was already going to be larger for X if we assumed perfect phase noise LO because of the lower efficiency of those devices. We still need a certain EIRP to close the link and lower efficiency does not lower the requirement to emit a certain EIRP. Since there is a fixed power budget given the proposed size, we would have to take power from the linear transponder, etc. we seem to be working to protect. The greatly increased pointing requirements on the spacecraft and ground (with 4 times as many elements on power amplifiers needed on the spacecraft for the phased array) given our constant aperture solution, coupled with lower efficiency leading to increased DC power consumption on the spacecraft, and with the inevitably higher phase noise all seem to mitigate against attempting X. I would need to see a design with some numbers but let's just say that for now I dismiss this proposal until somebody proves my entire thinking to be way off base.
We are left with S1 and S2 as the possible uplinks for the DCP that preserves the CC&R, first responder communications system. It is the contention of Emily that U/V is a crap choice for the linear transponder. Yet P3E is including it as its primary transponder. But if we accept ther premise that we don't want to put this on U/V then that argues for L/S1 for the SDX and S2/C for the DCP and we give up on region 1 accessing our digital communications experiment and our first all microwave satellite.
All of these suggestions coming fast and furious need to slow and before finger hits the key, some consideration for how the suggestion impacts the entire system need to be undertaken as requirement 1 in your personal analysis before the suggestion hits the street.
Bob
I put in a tentative bid for almost $250,000 in the upcoming budget for engineering for the coming year but no one is going to allow to me say I need about a quarter mill, trust me. If I call Jim and he does not have your team's budget numbers (as in I have not submitted numbers either), then I am going to call you to get them (I just gave myself a call). I am going to get some kind of SWAG at a number that includes hardware, travel, tools, and telecommunications. We are putting together a unified engineering budget that includes Eagle, P3E, Suitsat II, etc. so these numbers are needed.
On our system recommendation, I am going to get a decision on the overall plan before the board meeting as to the final form of our recommendation so Jim can present that to board. If this decision must be made by one or two people, so be it. We are going to decide on the system by then. PERIOD. If you have a dog in this fight, give that cur a kick in the rear.
John B. Stephensen wrote:
I'm guessing that a worldwide ITU allocation results more availability than when one region is excluded. I beleive that Bob has asked for hard information on non-availability of S1 in countries outside the U.S. Perhaps the question should cover the entire microwave spectrum.
73,
John KD6OZH
----- Original Message ----- From: "Lee McLamb" ku4os@cfl.rr.com To: "'EAGLE'" eagle@amsat.org Sent: Friday, September 15, 2006 22:59 UTC Subject: [eagle] Re: C-C Rider Band Plan Follow-up
We also (re)learned after the fact that ITU allocation by region isn't the same as the individual countries allowing use within their borders. As a result S1 as an uplink doesn't really solve the problem of world-wide access either. Given that experience, how confident are we that C/X would be any more or less accessable?
From what I've seen so far, Rick's proposal appears to strike a very
reasonable balance. Perhaps compiling a database of band authorizations by country would be a good project for AMSAT-International.
73, Lee-McLamb
On Fri, 2006-09-15 at 10:14 -0400, Rick Hambly (W2GPS) wrote:
John,
You say "I still like S1/C, but if there is decision that it isn't feasible for non-technical reasons and we can't be absolutely certain that L/C will remain available everywhere through 2030, C/X is better than LS2/C by providing better worldwide availablity [sic] of the satellite."
My proposal (S2/C primary + L/C at apogee) is based on the best technical solution, as recognized at SDO, with mitigation for the political issues. I feel that if we abandon this opportunity to use the best band for the job, S2, we will never solve the Region 1 issue and we might as well give the band back. S2 has all the advantages of S1 without the interference noise.
Rick W2GPS AMSAT LM2232
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-- AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman "You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat." - Einstein
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