[Elecraft] RTTY and filters

[Joe Subich, W4TV]

Mike, 

My concern is that the 200 Hz filter might be too tight. 
With 170 Hz shift and 45.45 baud, the minimum bandwidth would 
be around 225 Hz (right at the rated - 6dB point of the "200 
Hz" filter) and probably closer to 310 Hz to maintain some of 
the "sharpness" of the shift.  

Lyle or one of the other DSP folks would know the minimum 
necessary bandwidth better that I do.  However but since the 
200 Hz roofing filter is not selected until the DSP bandwidth 
200 Hz or less it would be safe to suggest that a full 200 Hz 
configuration might be a little "too tight." 

I would think the "250 Hz" filter with its 370 Hz -6 dB 
bandwidth or even the 400 Hz filter with its 455 Hz -6 dB 
bandwidth would be more appropriate roofing filters for 
RTTY than the 200 Hz filter.  

73, 

   ... Joe, W4TV 
 

> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Mike 
> Fatchett W0MU
> Sent: Monday, January 07, 2008 1:29 PM
> To: Elecraft Discussion List
> Subject: [Elecraft] RTTY and filters
> 
> 
> I previously mentioned in an email to the group that I was 
> looking forward to trying out the 200hz filter in my K3 for 
> RTTY contesting.   I had one reply wondering if that filter 
> was going to be too tight for RTTY.
> 
> Any comments from the group on this.
> 
> The other person that emailed was planning on using the 400hz 
> filter.
> 
> 
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