[amsat-bb] Re: Eagle U/V modes

[John B. Stephensen]

800W EIRP should work -- the SNR will just be 2 dB lower. We used 1 kW EIRP 
as the requirement as it is the power limit in many parts of the U.S. I 
don't remember any publishedspecification for the AO-40 uplink, so I can't 
make a numberical comparison.

73,

John
KD6OZH

----- Original Message ----- 
From: "Greg D." <ko6th_greg at hotmail.com>
To: <kd6ozh at comcast.net>; <kb5mu at amsat.org>; <tmcgrane at suffolk.lib.ny.us>
Cc: <amsat-bb at amsat.org>
Sent: Thursday, October 12, 2006 04:15 UTC
Subject: [amsat-bb] Re: Eagle U/V modes


> 1kw EIRP...  I've got about 100w into a 2x8 CP antenna (guessing 8dbi ?), 
> so
> that's about the same.  How does this compare to the uplink requirements 
> for
> U/S on AO-40?  I was able (accidentally) to get Leila's attention with 
> that.
>
> Greg  KO6TH
>
>
> ----Original Message Follows----
> From: "John B. Stephensen" <kd6ozh at comcast.net>
> To: "Greg D."
> <ko6th_greg at hotmail.com>,<kb5mu at amsat.org>,<tmcgrane at suffolk.lib.ny.us>
> CC: <amsat-bb at amsat.org>
> Subject: Re: [amsat-bb] Re: Eagle U/V modes
> Date: Wed, 11 Oct 2006 07:14:05 -0000
>
> We're planing on 1 kW PEP EIRP (25 W into a 14 dBic antenna) U-band 
> uplinks
> for SSB on Eagle.
>
> 73,
>
> John
> KD6OZH
>
> ----- Original Message ----- From: "Greg D." <ko6th_greg at hotmail.com>
> To: <kb5mu at amsat.org>; <tmcgrane at suffolk.lib.ny.us>
> Cc: <amsat-bb at amsat.org>
> Sent: Wednesday, October 11, 2006 04:08 UTC
> Subject: [amsat-bb] Re: Eagle U/V modes
>
>
>>Two thoughts on Paul's comments:
>>
>>1.  I was also excited by what I heard about the Text Messaging proposal.
>>Has anybody approached (or future tense, could anyone approach) Kenwood 
>>for
>>a re-program of their TH-D7?  I suspect that the internal processing
>>capabilities won't be sufficient, but if it worked, that might provide a
>>readily available platform for a new product.  If not the D7, maybe the
>>D700?
>>
>>2.  What I thought I heard at the Symposium was that we wouldn't need such
>>a
>>massive station to work Eagle's traditional UV transponder.  While I 
>>expect
>>there were many such "baseline" stations in existence around the planet, I
>>wonder how many are still operational after years of no HEO UV birds and
>>all
>>the affects of weather?  Then there are those of us who cannot put such a
>>station on the air, lacking the space and/or neighborhood setting (cc&r) 
>>to
>>do so.  I managed a few contacts on AO-10 and one on AO-13 with my 8
>>footer,
>>under unusually good conditions, but they were an ear strain.  I had
>>planned
>>to need to go to LS on Echo until the Symposium convinced me that I'd be
>>fine on UV.  Do I need to re-think that?
>>
>>Thanks to all the presenters at the Symposium.  Great event!
>>
>>Greg  KO6TH
>>
>>
>>----Original Message Follows----
>>From: Paul Williamson <kb5mu at amsat.org>
>>To: McGrane <tmcgrane at suffolk.lib.ny.us>
>>CC: Amsat BB <amsat-bb at amsat.org>
>>Subject: [amsat-bb] Re: Eagle U/V modes
>>Date: Sun, 8 Oct 2006 09:39:56 -0700
>>
>>At 10:23 AM -0400 10/8/06, McGrane wrote:
>> >Could someone please explain further the capabilities of the U/V text
>> >messaging mode. Would this incude the use of typical packet equipment?
>>
>>No. In order to transfer information (even at low data rates) with
>>very small antennas and low power, it's necessary to use every trick
>>in the digital optimization book, so it won't be compatible with
>>existing packet equipment.
>>
>>By very small, it's meant that the radio might clip onto the back of
>>a handheld PDA, with an antenna system small enough to be manageable
>>handheld. Probably not as small as a rubber duckie, but something
>>that doesn't need pointing. Exact details are still to be designed.
>>
>>There's not a lot of detail yet about how the system will work from a
>>user standpoint. The work so far has been on making the links work
>>and determining the spacecraft requirements. For higher level
>>architecture, one idea is to use Jabber, which is an open protocol
>>for instant messaging (keyboard chat) used on the internet. It's
>>thought that many of the applications that work on APRS would work
>>great on this system (not just positioning).
>>
>>Now would be a good time to throw out your ideas for applications for
>>a service like this, so the system designers can try to accommodate
>>them.
>>
>>(The above info is based on what I heard at the Space Symposium and
>>not to be considered official in any way.)
>>
>> >Could some old timers describe a typical AO-13 or AO-40 mode U/V station
>> >for my education and to help me build a station.
>>
>>The baseline AO-13 Mode B station was a 20-foot-long circularly
>>polarized cross-yagi for 2m, plus a 14-to-20-foot circularly
>>polarized cross-yagi for 70cm, mounted for azimuth and elevation
>>rotation. Rather short low-loss coax feed (e.g., Belden 9913) or a
>>mast-mounted low-noise preamp on the downlink. On the uplink,
>>operators who wanted to work under all conditions had about 100 watts
>>available, but under good conditions much less power was needed.
>>Continuously variable uplink power was considered mandatory since
>>being too loud is bad practice and being too weak meant marginal
>>stations couldn't hear you. SSB and/or CW capability on the radios.
>>Most conveniently, a single-box "satellite" rig would allow the use
>>of a single knob to tune around the transponder, but separate
>>transmit and receive rigs were also common.
>>
>>Seriously hard-core stations who wanted to hear down to the
>>transponder noise floor even when conditions were poor would phase
>>two or more of the 20-foot cross-yagis. It was good to have a few of
>>those stations around to pick out the very weak uplinks, but it
>>wasn't really necessary for most users to have that much gain.
>>
>>Computer control of the rotators was convenient but not necessary,
>>since the satellite moves slowly across the sky. Likewise computer
>>control of radio frequency was generally not required, since the
>>Doppler shift changed rather slowly.
>>
>>73  -Paul
>>kb5mu at amsat.org
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>
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