[RTTY] Filters

Jim Reisert AD1C jjreisert at alum.mit.edu
Sat Mar 27 09:20:50 EST 2004

At 10:21 AM 3/24/2004, Bill Turner wrote:

>When I'm using a 250 Hz filter, quite often when two stations are within
>10-20 Hz of each other and nearly the same strength, I can tune off to
>the side and get clear copy, something that probably would not happen
>with a wider filter.  Just something to keep in mind.

This doesn't have anything to do with the filter bandwidth, but rather the 
shape.  If the shape is very "square" then you will get good rejection just 
outside the passband.  If it slopes more gradually, the rejection will be 
reduced.  DSP filters like in the IC-756 are very good at these sorts of 

73 - Jim AD1C

Jim Reisert AD1C, 7 Charlemont Court, North Chelmsford, MA 01863
USA +978-251-9933, <jjreisert at alum.mit.edu>, http://www.ad1c.com
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