Re: [amsat-bb] Re: Why preference for mode J?

["Norbert Sayou" <norbert.sayou@xxxxxxxxxx>]

Hello

There are same problems in south america...on AO27 UO14 and FO20 who can
transmit FM QRM (!!!)

FY1DW  Norbert

----- Original Message -----
From: Tony Langdon <tlang@freeway.apana.org.au>
To: <amsat-bb@AMSAT.Org>
Sent: Sunday, July 30, 2000 7:39 AM
Subject: Re: [amsat-bb] Re: Why preference for mode J?


>
> Hello Jim.
>
> 29 Jul 00 18:39, you wrote to Tony Langdon:
>
>  JW>     A couple comments about the preference for mode J.  I understand
>  JW> the Asian QRM problem.  We have the same problem around here with
>  JW> Tijuana Taxi on the UO-14 uplink.
>
> Oh, OK.  Yes, the Asian problem is severe.  A pass over the West
Australian
> border is useless from AOS for the first 5 minutes, and een by mid pass,
there
> is still sporadic QRM.  This isn't one company, but _masses_ of stations.
> Sounds like the dogpiles one gets in the middle of a major contest or when
the
> rare DX pops up!.
>
> I just uploaded a MP3 which gives a vague idea of what the QRM is like.
There
> will be a more suitable pass this week which should give me a better
> opportunity to record the QRM.  Look up the July 29 entry on
> http://www.qsl.net/vk3jed/sat.html
>
>
>  JW>     What is the issue with the typically equipped FM station that
>  JW> would be any different between mode V-U (or J) and U-V (or B).  I
know
>
> It's the radiation angle of most peoples' antennas.  If 70cm is the
uplink, the
> station can use power to compensate (partially) for the poor antenna
> performance (the average FM base has 25-50W, compared to a 0.25-5W for the
> average transponder).
>
> Obviously, those who get serious do install suitable antennas, or go
portable
> with beams and the like.
>
>  JW> receiving 435 MHz here in the Los Angeles is much easier than 2M due
>  JW> to the much lower noise floor.  Also
>
> Well, same here, but it's not 9dB worse on 2m. :)  The only areas where 2m
is a
> wipeout is the central few km of the cities and the odd locations close to
> paging transmitters.
>
>  JW> remember that in some parts of the world, mode U-V is not available
>  JW> due to 435 MHz not being authorized for amateurs.  Charlie - VR2XMT
in
>  JW> Hong Kong has commented about that before.
>
> Oh, OK.
>
> Tony
>
> .. What if there were no hypothetical situations?
> --
> |Fidonet:  Tony Langdon 3:633/284.18
> |Internet: tlang@freeway.apana.org.au
> |
> | Standard disclaimer: The views of this user are strictly his own.
>
>
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