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

Greg D. ko6th_greg at hotmail.com
Wed Oct 11 21:15:28 PDT 2006

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.



----- 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
>2.  What I thought I heard at the Symposium was that we wouldn't need such 
>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 
>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 
>under unusually good conditions, but they were an ear strain.  I had 
>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
>(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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