K3's RF Clipping Speech Processing

[Jack Smith-6]

I've added a page with some measurements of the K3's RF speech clipping
functionality, including sample sound records, oscilloscope envelope
views and spectrum analyzer captures.

http://www.cliftonlaboratories.com/elecraft_k3_speech_processing.htm

Jack K8ZOA
www.cliftonlaboratories.com
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[n7ws]

Nice job (as always).  I haven't had a chance to really study it in depth, but one comment" audio clipping is a viable method too.

Wes N7WS


--- On Sun, 3/15/09, Jack Smith <[hidden email]> wrote:

> From: Jack Smith <[hidden email]>
> Subject: [Elecraft] K3's RF Clipping Speech Processing
> To: "'Elecraft'" <[hidden email]>
> Date: Sunday, March 15, 2009, 5:09 PM
> I've added a page with some measurements of the K3's
> RF speech clipping
> functionality, including sample sound records, oscilloscope
> envelope
> views and spectrum analyzer captures.
>
> http://www.cliftonlaboratories.com/elecraft_k3_speech_processing.htm
>
> Jack K8ZOA
> www.cliftonlaboratories.com
> ______________________________________________________________
> 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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[Julian, G4ILO]

Wes Stewart wrote

Nice job (as always).  I haven't had a chance to really study it in depth, but one comment" audio clipping is a viable method too.

With audio clipping harmonics of the clipped audio can fall within the audio passband wasting power and reducing intelligibility. RF clipping avoids this.

[n7ws]

--- On Mon, 3/16/09, Julian, G4ILO <[hidden email]> wrote:

> From: Julian, G4ILO <[hidden email]>
> Subject: Re: [Elecraft] K3's RF Clipping Speech Processing
> To: [hidden email]
> Date: Monday, March 16, 2009, 2:06 AM
> Wes Stewart wrote:
> >
> >
> > Nice job (as always).  I haven't had a chance to
> really study it in depth,
> > but one comment" audio clipping is a viable
> method too.
> >
> >
> With audio clipping harmonics of the clipped audio can fall
> within the audio
> passband wasting power and reducing intelligibility. RF
> clipping avoids
> this.

http://k6mhe.com/n7ws/S_PROC.pdf


     
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[Ignacy]

Excellent page. It confirms that the point of diminishing returns is compression of 25. Very effective and some 10db stronger than no compression. When the signals are strong, few see benefits of going below 15. So 15 for ragchewing and 25 for DX.  
Ignacy NO9E

Jack Smith-6 wrote

I've added a page with some measurements of the K3's RF speech clipping
functionality, including sample sound records, oscilloscope envelope
views and spectrum analyzer captures.

http://www.cliftonlaboratories.com/elecraft_k3_speech_processing.htm

Jack K8ZOA
www.cliftonlaboratories.com
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[Julius Fazekas n2wn]

Thanks Jack!

Based on your presentation and the voice settings, I'll be dropping my compression back a notch. Figure if it's easier for me to understand it will be easier for others to understand me (mumble mumble).

73,
Julius
n2wn

Jack Smith-6 wrote

I've added a page with some measurements of the K3's RF speech clipping
functionality, including sample sound records, oscilloscope envelope
views and spectrum analyzer captures.

http://www.cliftonlaboratories.com/elecraft_k3_speech_processing.htm

Jack K8ZOA
www.cliftonlaboratories.com
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[Jack Smith-6]

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[Julius Fazekas n2wn]

The higher clipping parameter seems to make the higher pitched voice less understandable. There does seem to be some "mushiness" to the lower pitched voice, but for my ears it seems less prominent.

The crispness of the 25 setting is how I would like to sound. I've had good reports with mine set at 30, but I can hear enough of a difference that I'm willing to go with clarity.

It doesn't seem to give up much in the way of "punch"...

Nice that you have a good test setup and willing to share your findings with those of us without :o)

73,
Julius

Julius Fazekas
N2WN

Tennessee Contest Group
http://www.k4ro.net/tcg/index.html

Tennessee QSO Party
http://www.tnqp.org/

Elecraft K2/100 #4455
Elecraft K3/100 #366


--- On Mon, 3/16/09, Jack Smith <[hidden email]> wrote:

> From: Jack Smith <[hidden email]>
> Subject: Re: [Elecraft] K3's RF Clipping Speech Processing
> To: "Julius Fazekas n2wn" <[hidden email]>
> Cc: [hidden email]
> Date: Monday, March 16, 2009, 11:42 AM
> I was surprised at the intelligibility of speech
> with essentially zero amplitude variation - clipping level
> = 40. The
> envelope looks almost like FM, but the speech is still
> understandable,
> although not comfortable to listen to for extended periods.
> I had read
> this in one of the books written by the staff engineers at
> Collins
> Radio but didn't fully appreciate their comment at the
> time.
>
>
>
> Jack
>
>
>
>
>
> Julius Fazekas n2wn wrote:
>
>   Thanks Jack!
>
> Based on your presentation and the voice settings, I'll
> be dropping my
> compression back a notch. Figure if it's easier for me
> to understand it will
> be easier for others to understand me (mumble mumble).
>
> 73,
> Julius
> n2wn
>
>
> Jack Smith-6 wrote:
>  
>  
>     I've added a page with some measurements of the
> K3's RF speech clipping
> functionality, including sample sound records, oscilloscope
> envelope
> views and spectrum analyzer captures.
>
> http://www.cliftonlaboratories.com/elecraft_k3_speech_processing.htm
>
> Jack K8ZOA
> www.cliftonlaboratories.com
> ______________________________________________________________
> 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
>
>
>    
>  
>  
>
> -----
> Julius Fazekas
> N2WN
>
> Tennessee Contest Group
> http://www.k4ro.net/tcg/index.html
>
> Tennessee QSO Party
> http://www.tnqp.org/
>
> Elecraft K2/100 #4455
> Elecraft K3/100 #366

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[David Gilbert]

During the NAQP SSB contest in January, I heard a single-op somewhere in
the midwest calling CQ with a steady S9 +20db signal that was so
overcompressed that he was literally not understandable.  Nobody was
answering him, but lots of guys were commenting on his bad signal behind
his back.  So I gave him a call and told him all of that, and suggested
he crank back the supercharger.  He backed off the compression three
different times before he sounded crisp, and by the time he got there
his signal was S9 +5db but FAR more intelligible.

There were many South American contest stations during the recent ARRL
DX SSB contest that sounded like voice-modulated spark gap transmissions
... horrible stuff.  It often took several tries to ferret out their
callsigns, and what they thought they gained in terms of quick QSO rates
is beyond me.

The great thing about the K3 is that by speaking into the mic with the
monitor set loud enough to drown out your own voice (the one inside your
own head even while wearing headphones), you can set mic gain and
compression for your own perception of crisp intellgibility instead of
maximum average power out.  The two are definitely not the same.

73,
Dave   AB7E




Julius Fazekas n2wn wrote:

> Thanks Jack!
>
> Based on your presentation and the voice settings, I'll be dropping my
> compression back a notch. Figure if it's easier for me to understand it will
> be easier for others to understand me (mumble mumble).
>
> 73,
> Julius
> n2wn
>
>
> Jack Smith-6 wrote:
>  
>> I've added a page with some measurements of the K3's RF speech clipping
>> functionality, including sample sound records, oscilloscope envelope
>> views and spectrum analyzer captures.
>>
>> http://www.cliftonlaboratories.com/elecraft_k3_speech_processing.htm
>>
>> Jack K8ZOA
>> www.cliftonlaboratories.com
>> ______________________________________________________________
>> 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
>>
>>
>>    
>
>
> -----
> Julius Fazekas
> N2WN
>
> Tennessee Contest Group
> http://www.k4ro.net/tcg/index.html
>
> Tennessee QSO Party
> http://www.tnqp.org/
>
> Elecraft K2/100 #4455
> Elecraft K3/100 #366
>  

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[Julius Fazekas n2wn]

Agreed Dave...

I thought KV4FZ was way over compressed during ARRL DX SSB, along with a couple of the US M/M or M/S. The only advantage I could see was taking up a lot of room with basically a "KEEP OUT" sign posted.

I've had mixed results informing folks of lousy sounding signals on both CW and SSB. A few times have resulted in finding a problem and other have told me I don't know what I'm talking about...

Still playing with the SSB settings, and learning what works and what doesn't. I do need to adjust my self monitor level as I tend to keep it very low on CW so I can pick weak signals out better when running.

Muffled guys I have been skipping over if I can't figure the call out somewhat quickly.

Don't know which is worse, key clicks or Backman Turner Overdrive ;o)

Maybe see you in RDXC? probably in WPX ;o)

Good luck and do let me know if I sound like crap please!

73,
Julius

Julius Fazekas
N2WN

Tennessee Contest Group
http://www.k4ro.net/tcg/index.html

Tennessee QSO Party
http://www.tnqp.org/

Elecraft K2/100 #4455
Elecraft K3/100 #366


--- On Mon, 3/16/09, David Gilbert (via Nabble) <[hidden email]> wrote:

> From: David Gilbert (via Nabble) <[hidden email]>
> Subject: Re: [Elecraft] K3's RF Clipping Speech Processing
> To: "Julius Fazekas n2wn" <[hidden email]>
> Date: Monday, March 16, 2009, 1:43 PM
> During the NAQP SSB contest in January, I heard a single-op
> somewhere in
> the midwest calling CQ with a steady S9 +20db signal that
> was so
> overcompressed that he was literally not understandable.
> Nobody was
> answering him, but lots of guys were commenting on his bad
> signal behind
> his back.  So I gave him a call and told him all of that,
> and suggested
> he crank back the supercharger.  He backed off the
> compression three
> different times before he sounded crisp, and by the time he
> got there
> his signal was S9 +5db but FAR more intelligible.
>
> There were many South American contest stations during the
> recent ARRL
> DX SSB contest that sounded like voice-modulated spark gap
> transmissions
> ... horrible stuff.  It often took several tries to ferret
> out their
> callsigns, and what they thought they gained in terms of
> quick QSO rates
> is beyond me.
>
> The great thing about the K3 is that by speaking into the
> mic with the
> monitor set loud enough to drown out your own voice (the
> one inside your
> own head even while wearing headphones), you can set mic
> gain and
> compression for your own perception of crisp intellgibility
> instead of
> maximum average power out.  The two are definitely not the
> same.
>
> 73,
> Dave   AB7E
>
>
>
>
> Julius Fazekas n2wn wrote:
> > Thanks Jack!
> >
> > Based on your presentation and the voice settings,
> I'll be dropping my
> > compression back a notch. Figure if it's easier
> for me to understand it will
> > be easier for others to understand me (mumble mumble).
> >
> > 73,
> > Julius
> > n2wn
> >
> >
> > Jack Smith-6 wrote:
> >  
> >> I've added a page with some measurements of
> the K3's RF speech clipping
> >> functionality, including sample sound records,
> oscilloscope envelope
> >> views and spectrum analyzer captures.
> >>
> >>
> http://www.cliftonlaboratories.com/elecraft_k3_speech_processing.htm
> >>
> >> Jack K8ZOA
> >> www.cliftonlaboratories.com
> >>
> ______________________________________________________________
> >> 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
> >>
> >>
> >>    
> >
> >
> > -----
> > Julius Fazekas
> > N2WN
> >
> > Tennessee Contest Group
> > http://www.k4ro.net/tcg/index.html
> >
> > Tennessee QSO Party
> > http://www.tnqp.org/
> >
> > Elecraft K2/100 #4455
> > Elecraft K3/100 #366
> >  
> ______________________________________________________________
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