[K3] APF and Pitch

[Pierfrancesco Caci]

Someone mentioned that APF rings less when pitch tone is set to 440 Hz
instead of 800 Hz. So, I'm trying and it indeed seems to ring less.
Anyone else hearing this?
Is this some DSP effect or a psychoacustic effect?

Condition of test:
200Hz 5-pole filter
DSP BW 50Hz
RF gain backed so that signal is barely audible with no APF
RX Audio EQ bands 4 and 5 set to 0, all rest down -6

Pf

--
Pierfrancesco Caci, ik5pvx
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[Ken G Kopp]

I operate almost exclusively CW and my APF is never turned off.
I use a 400 Hz filter, BW set at @350 Hz, and a pitch setting of
440 Hz.

FWIW, I hear -no- "ringing".

73!

Ken - K0PP


On Sun, May 12, 2013 at 8:25 AM, Pierfrancesco Caci <[hidden email]> wrote:

>
> Someone mentioned that APF rings less when pitch tone is set to 440 Hz
> instead of 800 Hz. So, I'm trying and it indeed seems to ring less.
> Anyone else hearing this?
> Is this some DSP effect or a psychoacustic effect?
>
> Condition of test:
> 200Hz 5-pole filter
> DSP BW 50Hz
> RF gain backed so that signal is barely audible with no APF
> RX Audio EQ bands 4 and 5 set to 0, all rest down -6
>
> Pf
>
> --
> Pierfrancesco Caci, ik5pvx
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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[Pierfrancesco Caci]

thanks Ron, I guess this relates to Q=f/deltaf ? Didn't even think of
this, and it's interesting that the effect is noticeable at these
frequencies.

Pf



>>>>> "Ron" == Ron D'Eau Claire <[hidden email]> writes:


    Ron> I believe that you'll find that is true of any filter. By cutting the tone
    Ron> frequency almost in half (800 to 440 Hz), you almost double the effective
    Ron> width of the passband. That leaves more room for the keying sidebands which
    Ron> means less "ringing" or stretching of the keying transitions.

    Ron> (I like lower frequency tones too.)

    Ron> 73 Ron AC7AC

    Ron> -----Original Message-----
    Ron> From: [hidden email]
    Ron> [mailto:[hidden email]] On Behalf Of Pierfrancesco Caci
    Ron> Sent: Sunday, May 12, 2013 1:25 AM
    Ron> To: [hidden email]
    Ron> Subject: [Elecraft] [K3] APF and Pitch


    Ron> Someone mentioned that APF rings less when pitch tone is set to 440 Hz
    Ron> instead of 800 Hz. So, I'm trying and it indeed seems to ring less.
    Ron> Anyone else hearing this?
    Ron> Is this some DSP effect or a psychoacustic effect?

    Ron> Condition of test:
    Ron> 200Hz 5-pole filter
    Ron> DSP BW 50Hz
    Ron> RF gain backed so that signal is barely audible with no APF RX Audio EQ
    Ron> bands 4 and 5 set to 0, all rest down -6

    Ron> Pf

    Ron> --
    Ron> Pierfrancesco Caci, ik5pvx


--
Pierfrancesco Caci, ik5pvx
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[Mike K4PI]

I use 350 hz pitch and with a decent signal the APF works okay although its not really needed under those conditions.  When the signal is very very weak it is hard for me to tell when the stations stops sending, ie the ring from noise burst sounds the same as the station transmitting.  For that reason it is very annoying.  I have spent time on 160 trying to copy something with APF that I cant without but cant find where it really helps.  It does sound neat when you turn it on and peak up signals and maybe if there were no noise burst at all it might be more useful.  I use dual QF-1A audio filters for stereo while has more control for me being able to control each ear separately.   73 Mike K4PI
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