[amsat-bb] Re: S band and Eagle: an appeal for a higher leveldiscussion

Thu Sep 7 21:23:30 PDT 2006

O.K. S or no S we are 5 years to launch. Forcasting band conditions and QRM 
at that point in time is 95 % dark clouds and 5% reality! getting satellite 
anything, built, tested, launched, and operational is not an easy task, 
certainly fnot for the faint of heart! If we do not decide now what we use 
we will not have anything at launch time even with 10,000 sidewalk engineers 
on the job!.  .
The 10 GHz band is the only band that does not provide for part 15 ISM 
equipment.
2.4 and 5.8 are good places to transmit. Pyro Joe has had some good deals on 
30 + watt 2.4 GHz amps @ reasonable prices. I use one on ATV 18 MHz wide FM, 
not a lot of 2.4 activity here! Hmm. Maybe we should all be on ATV until P3E 
is operational.

Art,
KC6UQH
----- Original Message ----- 
From: "Joe Westbrook" <k7zt at cox.net>
To: <brobertson at mta.ca>; <amsat-bb at amsat.org>
Sent: Thursday, September 07, 2006 6:01 PM
Subject: [amsat-bb] Re: S band and Eagle: an appeal for a higher 
leveldiscussion

> Bruce:
> Are you suggesting that "Please,, those of you who are qualified and
> competent"  are the only folks who are worthy of a dissenting view 
> regarding
> this topic?  Please, that is precisely the attitude that turn folks off of
> AMSAT-NA, that elitist attitude has no place in a HOBBY.  Particularly 
> when
> we ALL contribute to the construction of the satellites.  It just happens
> that I am a professional Network Engineer (Trainer) for a 
> Telecommunications
> Company.
>
> My background spans virtually every communications technology from DC to
> Daylight.  I have an extensive background in EMI/RFI Labatory Testing,
> culminating in  35+ non-stop years in the Communications field.  No I 
> don't
> have any matamatical studies, what I do  have is first hand empirical
> experience in a neighborhood where EVERY Home has at least a single 2.4GHz
> radiation source .
>
>  I worked AO-40 and thoroughly enjoyed the S Band downlink and have
> maintained the station in anticipation of continuing this activity on the
> HEOs.  I'm not alone, I'm sure that the majority of members who have made
> the S Band and Investment.
>
> Do I get interference from the IEEE 802.X devices and portable phones, 
> yes,
> in the form of random clicks that are easily removed by using a noise
> blanker, try it works great!
>
> What, if any studies considered that 5.2Ghz devices are taking off now and
> will probably eclipse the 2.4Gig interference levels.  Make any argument 
> you
> wish for dropping S Band from Eagle, but don't use the polluted spectrum
> argument, it simply doesn't hold water.
>
> Regards,
> Joe, K7ZT
>
> ----- Original Message ----- 
> From: "Bruce Robertson" <broberts at mta.ca>
> To: <amsat-bb at amsat.org>
> Sent: Thursday, September 07, 2006 5:06
> Subject: [amsat-bb] S band and Eagle: an appeal for a higher level
> discussion
>
>
>> There has been a recent restatement of disappointment regarding the Eagle
>> design committee's recent choice to use S band as an uplink not a
>> downlink.
>> Note that the next two HEO's scheduled to launch *will* have S band
>> downlinks, so there's no worry that people like I, who live in radio 
>> quiet
>> areas, will be unable to use our developing S band equipment in the
>> future.
>>
>> 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.
>>
>> The design team have said again and again on this list that they would
>> welcome contradicting evidence that is cogent, and I, for one, believe
>> them. They're our volunteers, and they deserve our support. I can't
>> provide
>> that contradicting evidence: I'm not skilled or qualified. But I can
>> assess
>> an argument, and the responses so far have not been nearly as rigorous.
>> They have amounted to "works for me", which I think misses the point.
>>
>> Please, please, those of you who are qualified and competent and hold the
>> opposing opinion, take the design committee at their word and assess 
>> their
>> work, check their assumptions, present cogent opposing arguments. There 
>> is
>> some thought that a dish antenna properly implemented will overcome the
>> obstacles described by the design team. Let's model this. Or those who
>> live
>> in heavy 802.11b environments, do some experiements with terrestrial 
>> links
>> (which I suppose could be assumed worse than earth/sky). Who knows? Maybe
>> it's all like my last tax return, where a missed decimal point made me
>> think I'd have to take out a second mortgage to pay our taxes :-) This
>> list
>> and the wiki exist so that we can undertake that sort of dialogue, and 
>> for
>> my part, it is my favorite part of participation in AMSAT.
>>
>> Some have suggested that Eagle fly with an S-band downlink on the off
>> chance that it *does* work despite the theory; others, that we survey the
>> members to see what they'd like. I fully support the design teams
>> rejection
>> of the former approach. Launch weight is very expensive and the kitchen
>> sink approach is not to my mind sensible. As to the latter, a survey
>> presumably pertains only to *working* bands, not ones that are polluted
>> out
>> of existance.
>>
>> It's human nature for us more readily to see our misfortunes as caused by
>> the malace of others, but I think we should strongly avoid terms like
>> "bait
>> and switch". We'll get much further if we all assume the goodwill of
>> everyone involved.
>>
>> 73, Bruce
>> VE9QRP
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>
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