Re: [amsat-bb] This Weekend in Minneapolis: Central States VHF Society Meeting

[Jim Sanford <wb4gcs@xxxxxxxxx>]

Gents:
I am on the way out the door, back later this am.

I can answer some of these issues later today.  All will be answered in 
detail in the next issue of the AMSAT Journal.

73,
Jim
wb4gcs@amsat.org
Eagle Project Manager


Edward R. Cole wrote:

>Andrew,
>
>At 11:44 PM 7/29/2006 -0400, Andrew Glasbrenner wrote:
>  
>
>>Jim and all,
>>
>>If I read things correctly Eagle will still carry a S-band beacon? It seems 
>>to me if we go to the trouble of including a transmitter and antenna, we 
>>might as well provide a little passband for those who don't have the 
>>interference issues? Even say 25 khz?
>>    
>>
>
>When I proposed this to Bob McGwier, he responded that they would not be
>providing S-band downlinking.  All I can guess from this is that no
>provision is being considered for linear transponding.  Perhaps the beacon
>is psk digital, only?
>
>  
>
>>I read with interest accounts of people with interference on S-band, and I 
>>notice that there may be a common thread. Many of the antennas used for 
>>reception on AO-40, and even more used for AO-51 are not very effective at 
>>blocking sidelobes and thereby mitigating interference. It may be (and 
>>certainly is in my own experience) that successful weak signal S band HEO 
>>operation is going to require more than a BBQ dish and unprotected feed, or 
>>a helix wound on some PVC pipe. My own AO-40 downlink antenna was nearly 
>>immune from interference when above 15-25 degrees, including from the WAP 
>>and video sender in my own house. This was in an urban environment where I 
>>routinely could see 5-6 local WAPs on a wifi PC in the yard, and over a 
>>dozen with a gain antenna. My dish was very simple. 36" prime focus, with a 
>>homemade helix feed in a cup to reduce sidelobes. All of this was mounted 
>>with 70cm and 2m CP yagis on a G5500 on a roof tripod. The dish and homebrew 
>>feed and mounts cost less than 100$. Just another anecdotal data point for 
>>your consideration.
>>    
>>
>
>I do not live in urban America so cannot guess how bad WiFi is or will be,
>but your reasoning seems logical to me.  What I am hearing is the subject
>of L or S-band is closed for Eagle.
>
>  
>
>>I understand that Eagle II is being considered as a close follow-on for 
>>Eagle I? Maybe there can be some diversity of modes between the two 
>>satellites, say U/V and S/C on I and UL/S and C/X? on II?
>>    
>>
>
>I asked about mode-X and got no response to my question, so I gather that
>it is not being included on Eagle-I.  If I were to guess it may be an
>attempt to not repeat trying to build a satellite with everything on it
>(like AO-40).  So the choice is for one VHF/UHF transponder and one mw
>transponder; one analog voice and one digital voice/video.
>
>But if I have any assumptions wrong I hope a member of Eagle design team
>will correct or clarify.  Really, I should not speculate as too many folks
>will read this as "fact".  
> 
>73's,
>Ed - KL7UW 
>===================================
>BP40iq,  Nikiski, AK      http://www.qsl.net/al7eb
>Amsat #3212
>Modes: V - U - L - S
>===================================
----
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