[Elecraft] K3 Filter questions

[k.igor at comcast.net]

Actually, my first point exactly is that hearing is subjective, the setting that works for you may not be good for somebody else. And there is nothing wrong with this. My other point is that from technical point of view, you reduce significance of the DSP filter with this setup, which is fact as opposed to categorical unbased statement from somebody that this is not true. That is all and I consider this thread is closed for me. 

  

73, 

Igor, N1YX   



----- Original Message -----




From: "Dave Hachadorian" <k6ll at arrl.net> 
To: "Elecraft Reflector" <elecraft at mailman.qth.net> 
Sent: Wednesday, March 28, 2012 3:55:56 PM 
Subject: Re: [Elecraft] K3 Filter questions 

Igor, 

You are missing the point.   K8ZOA's measurements were for a 
continuous carrier. You can't measure speech intelligibility with 
the K3's dBV meter. 

My  recommendation for DSP bandwidth of 2.1 KHz and 1.8 crystal 
filter were based on what I consider the best compromise between 
bandwidth and intelligibility for SSB human speech. 

Look at it this way - My ears find SSB speech very 
intelligible with a DSP bandwidth of 2.1 KHz.  You can put a 1.8 
crystal filter in front of that DSP and SSB STILL is very 
intelligible, plus you have the advantage of a nice tight roofing 
filter to keep the hardware AGC from pumping.  When you start 
reducing the DSP bandwidth below 2.1 KHz, intelligibility starts 
to become very dependent on the voice characteristics of the 
received signal, so you have to keep fiddling with the DSP 
controls.  You don't want to be fiddling with the controls if you 
are running at 200 QSO's per hour.  I'm saying that with DSP 2.1 
and a 1.8 roofing filter, one can pretty much leave the controls 
alone for the duration of the contest. 

After the contest is over, you can go back to 2.7/2.7 filters for 
more natural-sounding audio. 

Dave Hachadorian, K6LL 
Yuma, Arizona 


-----Original Message----- 
From: k.igor at comcast.net 
Sent: Wednesday, March 28, 2012 11:05 AM 
To: jim at audiosystemsgroup.com 
Cc: elecraft at mailman.qth.net 
Subject: Re: [Elecraft] K3 Filter questions 



If it pleases you to use DSP set wider than roofing filter - by 
all means, go for it. 

I would not, however, clame objectivity based on my subjective 
experience  or somebody's valuable opinion and simplistic 
explanation , I perefer measurements performed on good lab 
equipment. K8ZOA did some of the measurements on 500 Hz filter, 
but most of them probably applicable for the 1.8kHz filter. See 
report here: 
http://www.cliftonlaboratories.com/elecraft_k3_noise_blanker_and_crystal_dsp_filtering.htm 

In his measuremetns, setting DSP wider than the actual roofing 
filter actually degraded the total response in the stop band. 



73, 

Igor, N1YX 

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