Hi mode-S users:
I've read the comments (and their are quite a few...hint!), before adding my opinions.
First of all P3E has a much closer (we hope) launch date and is much further down the road in construction. I'm guessing they didnot anticipate that the WiFi generated noise floor posed a significant problem. Perhaps they can provide a larger mode-S ERP (I haven't compared spec's between the original Eagle and P3E). In any case, I am glad that P3E will fly both mode-S and Mode-L...and then we will see the "truth" in the Eagle engineering projections!
I wrote Bob McGwier (N4HY) soon after the referenced presentation was put out as a web-link (I believe it was slated to be presented at this years symposium, so was not intended to be pre-released). But many of us read it and discovered the major project changes that have been decided by the design team (dion't you think major shifts in design ought to have some public comment input ...i.e the users).
I proposed that the mode-S translator (S2) be flown as a contingency module to the beacon Tx (S1, I believe) and tested in orbit as a linear transponder. If the noise floor issue is found to be a problem then the module would just sit in standby (in case of failure of S1). Bob rejected that proposal.
Now, I'm hearing folks talk about the C-C Rider project but that has also been scrapped (at least as a 5-GHz in-band transponder) according to the presentation. What I understood was that mode-C would be used for digital-voice and video downlink with mode-S uplink.
BTW Eaglepedia does not reflect any of the recent design changes. An considerable portion is only outline with no content. The general membership will be challenged to follow the evolution of design (meetings) in order to discover what is the current version of the project. I guess we will see in time how that Eaglepedia works out.
Unless the membership (read this as users...quite a few with recent AO-40 experience) can sway the design, I see big issues looming for Amsat-NA "management". I for one will use the mode-UV transponder on Eagle and mode-LS on P3E. Since I will be on social security by the time Eagle is launched, I have little prospects for funding new mw bands. But we will see!
one users opinion, Ed - KL7UW
At 06:57 PM 9/7/2006 -0500, Stefan Wagener wrote:
I have to agree with Bruce, however I don't take statements made by Bob McGwier (N4HY) (see below) for face value.
Quote by Bob(email to Amsat-bb on Tue 25/07/2006): "In upcoming journal articles and in Eaglepedia documents showing the detailed calculations upon which our statements are based" Quote End
It is important that the data are presented, discussed, accepted or thrown out.
The main problem with the whole discussion is that the majority of folks have NOT seen the data. In addition, if the data are as sound as they are portrait, why is AMSAT-DL not believing in them and is including S-band as a downlink. How is the discussion between ANSAT-NA and AMSAT-DL going on this?
The lack of transparency is concerning and Eaglepedia is just an empty word if key documents and information is not published especially if it is available. Waiting for journal articles to come does not help. At the same time Eaglepedia still has the now "old" mechanical design specs and information on the S-band TX transponder available with no indication that both are obsolete.
73, Stefan VE4NSA
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Bruce Robertson Sent: September 7, 2006 5:06 PM To: amsat-bb@amsat.org Subject: [amsat-bb] S band and Eagle: an appeal for a higher level discussion
....As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch.....
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73's, Ed - KL7UW =================================== BP40iq, Nikiski, AK http://www.qsl.net/al7eb Amsat #3212 Modes: V - U - L - S ===================================