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Re: Circular polarity - Don't Bother!



But aren't you comparing apples and oranges? More specifically rhcp to lhcp,
and not cp to linear?

Drew, KO4MA
----- Original Message -----
From: Bill Magnusson <williamb@netc.net.au>
To: <amsat-bb@AMSAT.Org>
Sent: Saturday, December 30, 2000 6:09 PM
Subject: Re: [amsat-bb] Circular polarity - Don't Bother!


>
> Hi all,
>
> I always bite my tongue and walk around the chair 3 times before replying
to
> the list but here goes.
>
> As we say here in OZ  "it's horses for courses".
> If you are talking about a "power-house in the sky" like ao-40 promises to
> be then a minimal setup may suffice. Some amateur satellites can be worked
> using nothing more than a hand-held radio. But if you are talking about
> (let's say) the 38k4 digital birds like uo-36 and TiungSat-1 then let me
> assure you that CP does matter. I have switchable polarity yagis and if I
> leave the system work on auto and go off to do something else I return to
> find an overall d/l efficiency of 30 - 40 % and total download of maybe
> 500 - 600 kilobytes. If I'm here in the shack and watching the 's' meter
for
> polarity fades, the overall d/l efficiency is close to 100% and the total
> downloads 2.6 to 2.8 Megabytes per pass. I have watched polarity fades
take
> uo-36 from (remember these are FM readings) hard-over on the 's' meter to
> below the noise level in a matter of seconds. Below the noise level
equates
> to data lost.
>
> I guess most of the discussion on this list has centred around ao-40
> recently so this post may  be viewed by some as telling people how to suck
> eggs but there may be others who would interpret some of the recent posts
as
> applying to all amateur radio satellites .... Not so!
>
> Regards to all,
>
> Bill Magnusson ... vk3jt
> Milawa Australia
>
>
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