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Re: [RTTY] Great idea for the next 75 baud contest

To: rtty@contesting.com
Subject: Re: [RTTY] Great idea for the next 75 baud contest
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Mon, 21 Sep 2015 15:09:10 -0400
List-post: <rtty@contesting.com">mailto:rtty@contesting.com>

The only way to prevent this is to create several new Profiles for
75 baud, each from a different existing base Profile with different
taps and other settings. You will need to name them appropriately by
the baseProfile settings - Flutter 75, FIR 75, etc.

The "problem" with this is that the settings for 45.45 baud are not
appropriate for 75 baud.  In particular, one will need more bandwidth
for 75 baud ... profiles like the AA6YQ-FIR-512, "hyper sensitive"
and "EU1SA" are too tight for 75 baud - particularly in the presence
of multipath and/or selective fading.

I would expect the difference between 2-Tone decoding and MMTTY to be
much more pronounced at 75 baud than at 45.45 baud.

73,

   ... Joe, W4TV


On 9/21/2015 11:14 AM, Gary Senesac wrote:
Yeah but...

When you create this new Profile in MMTTY you are doing more than just just 
changing the baud rate settings. Whatever Profile you use for your base 
settings will also be used for your new 75 baud Profile. If during the contest 
you decide that MMTTY isn't decoding well enough and want to try switching to a 
different Profile you will find yourself back to 45 baud!

The only way to prevent this is to create several new Profiles for 75 baud, 
each from a different existing base Profile with different taps and other 
settings.  You will need to name them appropriately by the base Profile 
settings - Flutter 75, FIR 75, etc.

This problem may be mitigated somewhat if you run multiple decode windows using 
either other instances of MMTTY set for 75 baud, or multiple 2Tone instances 
set to 75 baud with different decode parameters.

Gary AL9A
Sent from my Kindle HDX

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