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Best CW Pitch???

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Steve Kallal

Best CW Pitch???

OK, I know this is personal preference thing. But with the K2, it isn't easy
to change CW pitch on the fly. While the sidetone frequency can be easily
changed, CAL FIL needs to be redone. Many other rigs will allow you to
select the CW pitch or offset on the fly.

I chose 400 Hz for my pitch. Sometimes I wonder if the best pitch varies
between rigs. I know it varies between bands. I can play with the K2 RIT
value and get at least +/- 50 Hz or more of variation from my 400 Hz
preference. Last night I readjusted the KAF2 pots and got the response more
centered around 400 Hz. It had been centered a little lower.

Last night I was working a CW station on 30 meters just in my noise level.
Usually I have to listen a little lower in pitch, but this time it helped to
listen a little higher. The band conditions seem to dictate the best pitch.

That said, I wonder how to best choose a pitch. I've thought of increasing
the pitch up to 420 or even 450 Hz. But I won't be able to return to 400 Hz
without running CAL FIL again, not a fast process. I definitely don't want
to go above 500 Hz. The 600 Hz default is very fatiguing to me and actually
piercing.

Again I know this is a personal thing. It really would be neat if the K2
firmware could be modified to accommodate several banks of filter settings
for different needs, such as CW pitches.

73,

Steve N6VL
K2 #2289

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drewko

Re: Best CW Pitch???

I had been using 650 Hz for awhile but decided to go to 800 Hz for
some reason. It just sounds better to me now. Maybe becuase I got used
to it while using my code practice program; higher pitch seems to
sound better for QRQ.

I was thinking of doing a bunch of filter alignments at sidetone
pitches 50 Hz apart, just to tabulate the filter settings. If you
recorded them all it wouldn't take very long to reprogram them when
you want to change sidetone pitch. It's only 4 three-digit DAC
numbers to dial in (or 8 if you want CW Rev). You could probably
change filters in a minute or so.

I was wondering, is there an electically optimal sidetone pitch which
the K2 prefers?

73,
Drew
AF2Z

On Fri, 28 Sep 2007 10:34:52 -0700, Steve N6VL wrote:

>OK, I know this is personal preference thing. But with the K2, it isn't easy
>to change CW pitch on the fly. While the sidetone frequency can be easily
>changed, CAL FIL needs to be redone. Many other rigs will allow you to
>select the CW pitch or offset on the fly.
>
>I chose 400 Hz for my pitch. Sometimes I wonder if the best pitch varies
>between rigs. I know it varies between bands. I can play with the K2 RIT
>value and get at least +/- 50 Hz or more of variation from my 400 Hz
>preference. Last night I readjusted the KAF2 pots and got the response more
>centered around 400 Hz. It had been centered a little lower.
>
>Last night I was working a CW station on 30 meters just in my noise level.
>Usually I have to listen a little lower in pitch, but this time it helped to
>listen a little higher. The band conditions seem to dictate the best pitch.
>
>That said, I wonder how to best choose a pitch. I've thought of increasing
>the pitch up to 420 or even 450 Hz. But I won't be able to return to 400 Hz
>without running CAL FIL again, not a fast process. I definitely don't want
>to go above 500 Hz. The 600 Hz default is very fatiguing to me and actually
>piercing.
>
>Again I know this is a personal thing. It really would be neat if the K2
>firmware could be modified to accommodate several banks of filter settings
>for different needs, such as CW pitches.
>
>73,
>
>Steve N6VL
>K2 #2289
>

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Don Wilhelm-4

Re: Best CW Pitch???

Drew,

There is nothing electrically preferred by the K2. If your BFO range is
adequate, the pitch can be set anywhere the BFO will support - and that
will usually allow a filter center frequency up to 1000 Hz.

However, look at the KAF2 and KDSP2 options for their upper frequency
centers (currently 800 Hz upper limit). A few capacitor and resistor
changes can move the KAF2 anywhere you want, but the KDSP2 would need
modified firmware to change its upper (or lower) limit.

While we are on the subject, I might say something about very low
pitches (since it has been mentioned) - there is a limit to how low you
can go and still retain the single signal reception because a
significant amount of the filter passband crosses over from zero Hz
pitch to the other sideband. In the extreme, you end up with the
response like a Direct Conversion receiver where the same pitch can be
heard (at equal amplitudes) on both sides of zero. One must consider
the IF filter skirt slope when deciding how low the filter can be set
while still retaining single signal reception. That is a situation that
potentially exists for any receiver, it is not unique to the K2. The K2
variable filter skirts do have a reduced slope at wider bandwidth
settings, and I suggest using Spectrogram (or equivalent) to observe the
actual filter slope when adjusting for a low pitch - make certain the
low frequency slope of the filter remains above zero Hz.

73,
Don W3FPR

[hidden email] wrote:
> I was wondering, is there an electically optimal sidetone pitch which
> the K2 prefers?
>
>
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Joe Subich, W4TV

RE: Best CW Pitch???

Don,

> While we are on the subject, I might say something about very low
> pitches (since it has been mentioned) - there is a limit to how
> low you can go and still retain the single signal reception because
> a significant amount of the filter passband crosses over from zero
> Hz pitch to the other sideband. In the extreme, you end up with the
> response like a Direct Conversion receiver where the same pitch can
> be heard (at equal amplitudes) on both sides of zero. One must
> consider the IF filter skirt slope when deciding how low the filter
> can be set while still retaining single signal reception.

How does (if it does) this change when the second filter is a DSP
filter/demodulator working at IF instead of at audio? For example,
in the K3 with the 500 Hz (565 Hz SF=3.1) roofing filter set for
a 250 Hz pitch the IF will have significant bandwidth "below zero
beat." If the DSP is set for 200 Hz bandwidth, will it include
response at the "audio image" or does the K3 DSP "filter before
demodulate?"

73,

... Joe, W4TV

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Don Wilhelm-4

Re: Best CW Pitch???

Joe,

I believe that has been taken care of for you in the K3 - but the low
limit could still be restricted in the firmware. With the DSP IF at 15
kHz, the answer to your question will depend on how the demodulation is
done in the DSP - but remember that DSP can produce very steep (and
deep) filter skirts, so the problem may not exist in a particular DSP
implementation. With DSP, there is no fixed 'signal path' like there is
in an analog receiver even though the processing may be represented that
way on a block diagram for simplicity of explanation..

The mathematical functions can all be merged if it is more convenient to
do it that way, and there is no real need to process one function first
and then do the next - that is the choice of the DSP programmer, and is
why one DSP receiver can sound different from another - it all depends
on the skills and creativity of the DSP programmer, and his decisions
about which techniques to use. All my statements here are, of course,
theoretical and not a reflection of that actually used in the K3 I know
Lyle and Wayne have done a good job, because I hear good things from the
Field Testers, and it is unimportant to me exactly how they have chosen
to implement a particular function.

As a parallel example, consider the process for calculating power when
one knows the resistance and the peak to peak RF voltage. It is quite
possible to work at the solution one step at a time - divide the Peak to
Peak voltage by 2, then multiply it by the square root of 2 to obtain
the RMS value, then square the result and divide by the resistance.
Each step takes time, but if one reduces the formulas necessary to do
the same computation, and plug the values into the resulting formula,
the peak to peak voltage can be directly squared and divided by 4 times
the resistance to obtain the same result in much less time than the
stepwise approach. The same principles work in any mathematical
computation, including those used for DSP - no magic, it is all in the math.

The problem of crossover to the other sideband is a situation that does
exist with component oriented filters, and needs an awareness of it when
aligning the IF filters in a K2 for a low pitch (which was the main
focus of my statements) - watch the response on the low frequency end of
the passband to avoid it.

73,
Don W3FPR

Joe Subich, W4TV wrote:

> How does (if it does) this change when the second filter is a DSP
> filter/demodulator working at IF instead of at audio? For example,
> in the K3 with the 500 Hz (565 Hz SF=3.1) roofing filter set for
> a 250 Hz pitch the IF will have significant bandwidth "below zero
> beat." If the DSP is set for 200 Hz bandwidth, will it include
> response at the "audio image" or does the K3 DSP "filter before
> demodulate?"
>
> 73,
>
> ... Joe, W4TV
>
>
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>
>

Roelof Bakker

Re: Best CW Pitch???

A lower pitch can be benficial because the same absolute frequency
difference between two CW signals is perceived different at a different
pitch.
Two signals 40 Hz apart are much easier seperated at a pitch of 400 Hz than
at a pitch of 800 Hz. At 800 Hz the difference is 5%. At 400Hz it is 10 %.
This is the way our BSP (biological signal processor) handles it.
At LF I have been using a pitch as low as 100 Hz to seperate signals with a
small spacing with excellent results.

73,
Roelof Bakker, pa0rdt
Middelburg, Netherlands
JO11tm

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Ken Kopp

Re: Best CW Pitch and filter ripple

In reply to this post by Don Wilhelm-4

I like 450 hz...

I've also found that trying to use anything much lower results in the
case someone else has given ... the opposite side of zero beat starts
to appear ... decidedly undesirable ... for me anyway.

Slightly related ... I note see four distinct "gain peaks" in the
waterfall
display of my PSK-31 program(s) when using wider filter settings.
I assume is is a product of the crystal filter's "ripple'.

73! Ken Kopp - K0PP
acninc.net
or
[hidden email]

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Jim Brown-10

Re: Best CW Pitch???

In reply to this post by Roelof Bakker

On Sat, 29 Sep 2007 18:56:26 -0000, Roelof Bakker wrote:

>Two signals 40 Hz apart are much easier seperated at a pitch of 400 Hz than
>at a pitch of 800 Hz. At 800 Hz the difference is 5%. At 400Hz it is 10 %.
>This is the way our BSP (biological signal processor) handles it.

Yes, this is very good advice.

Jim Brown K9YC

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Don Wilhelm-4

Re: Best CW Pitch and filter ripple

In reply to this post by Ken Kopp

Ken,

That is one reason I recommend using the OP1 filter (set the same as the
SSB FL1) for the RTTY FL1 setting. I make the RTTY FL2 thru FL4
settings narrow enough that there is no significant passband ripple (I
typically use 1.00, 0.70, and 0.40 centered at 1000 Hz).

In use, one would tune the desired signal with the VFO to the vicinity
of 1000 Hz in the waterfall display and then proceed as normal from
there (except that I 'lock the transmit frequency' in the PSK31
application so the QSO does not 'walk the band' due to the slight
difference between the transmit BFO and the BFO for the filter in use.

73,
Don W3FPR

Ken Kopp wrote:
>
> Slightly related ... I note see four distinct "gain peaks" in the
> waterfall
> display of my PSK-31 program(s) when using wider filter settings.
> I assume is is a product of the crystal filter's "ripple'.
>
> 73! Ken Kopp - K0PP
>
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Don Wilhelm-4

Re: Best CW Pitch???

In reply to this post by Don Wilhelm-4

Folks,

It has been pointed out to me that I left out one step in my stepwise
calculation for power - there is one more step to be added and that is
to divide by 2 one more time - that is usually done just after the
'multiply by the square root of 2' in the steps below.

Just one more reason I like to reduce the formulas before calculation,
it is less prone to mistakes than stepwise calculation. If you are not
familiar with formula reduction techniques, it is covered in High School
level algebra (or at least it was in mine back in the late 50s).

73,
Don W3FPR

Don Wilhelm wrote:

>
> As a parallel example, consider the process for calculating power when
> one knows the resistance and the peak to peak RF voltage. It is quite
> possible to work at the solution one step at a time - divide the Peak
> to Peak voltage by 2, then multiply it by the square root of 2 to
> obtain the RMS value, then square the result and divide by the
> resistance. Each step takes time, but if one reduces the formulas
> necessary to do the same computation, and plug the values into the
> resulting formula, the peak to peak voltage can be directly squared
> and divided by 4 times the resistance to obtain the same result in
> much less time than the stepwise approach. The same principles work
> in any mathematical computation, including those used for DSP - no
> magic, it is all in the math.
>

drewko

Re: Best CW Pitch???

In reply to this post by Jim Brown-10

On Sat, 29 Sep 2007 12:20:21 -0700, Jim Brown K9YC wrote:

>On Sat, 29 Sep 2007 18:56:26 -0000, Roelof Bakker wrote:
>
>>Two signals 40 Hz apart are much easier seperated at a pitch of 400 Hz than
>>at a pitch of 800 Hz. At 800 Hz the difference is 5%. At 400Hz it is 10 %.
>>This is the way our BSP (biological signal processor) handles it.
>
>Yes, this is very good advice.
>
>Jim Brown K9YC
>

Ok, that makes sense.

Now what about weak signals in noise (no QRM): any idea which pitch is
better there?

And I wonder about keying speed (element length): a shorter element
must carry better at a higher pitch I would think.

Of course, it doesn't matter much if your own ears have a problem with
the theoretical best pitch, i suppose.

73,
Drew
AF2Z

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Don Wilhelm-4

Re: Best CW Pitch???

Drew,

Like other things in life, one often must make compromises. That
compromise would ideally be made based on your preferences and with
knowledge of what is best for certain conditions.

We know that low pitches are better for the brain to separate two
different pitches (a signal in QRM), and we also know that very high
speed CW operators like a higher pitch because it is easier to discern
the code elements. If you belong to either group, your choice is
obvious, but I believe for most, the compromise using the Elecraft
default of 600 Hz makes sense - but you can change it for any reason if
you have a desire to do that.

I have heard that weak signal operators (i.e. EME) like to use a wide
bandwidth, but I have not heard about a preferred pitch.

73,
Don W3FPR

> Now what about weak signals in noise (no QRM): any idea which pitch is
> better there?
>
> And I wonder about keying speed (element length): a shorter element
> must carry better at a higher pitch I would think.
>
> Of course, it doesn't matter much if your own ears have a problem with
> the theoretical best pitch, i suppose.
>
> 73,
> Drew
> AF2Z
>
>

Don Wilhelm-4

Re: Best CW Pitch???

In reply to this post by Joe Subich, W4TV

Joe,

I believe you are mixing 'zero beat' with zero frequency audio (or DC) -
unless I misunderstood your note.

It makes no difference if the DSP is working at audio (baseband) or at
an IF frequency, the filtering is set to a specific width and the math
figures it out - the resulting signal that you hear is at baseband, but
that is only the output, not necessarily the processing, and IF DSP will
convert to baseband at its output so we can hear the result.

Properly done, a 500 Hz roofing filter would be centered above the audio
zero frequency entirely, so the roofing filter response would extend
from (say) 150 Hz up to 650 Hz - nothing on the opposite sideband, and
even if it does spill over a bit on the filter slope, the DSP can clean
it up.
Then the DSP takes over, and your 200 Hz Hz bandwidth at a 250 Hz pitch
would extend from 150 Hz to 350 Hz - still nothing on the opposite
sideband, and if the roofing filter had allowed a bit of opposite
sideband through (up to 150 Hz), the DSP would not allow it through.

Of course, this is much supposition on my part, I do not have the
details yet myself. If they get a break from pushing the K3 out the
door, maybe Wayne and Lyle will provide additional information about
'how it really works'.

I don't really think it is anything to worry about, but if there are low
frequency limits placed on the sidetone pitch, that may be the reason
why it is limited at the low end.

73,
Don W3FPR

Joe Subich, W4TV wrote:

Vic K2VCO

Re: Best CW Pitch???

Don Wilhelm wrote:

> Properly done, a 500 Hz roofing filter would be centered above the audio
> zero frequency entirely, so the roofing filter response would extend
> from (say) 150 Hz up to 650 Hz - nothing on the opposite sideband, and
> even if it does spill over a bit on the filter slope, the DSP can clean
> it up.
> Then the DSP takes over, and your 200 Hz Hz bandwidth at a 250 Hz pitch
> would extend from 150 Hz to 350 Hz - still nothing on the opposite
> sideband, and if the roofing filter had allowed a bit of opposite
> sideband through (up to 150 Hz), the DSP would not allow it through.

I can tell you that when set the crystal ('roofing') filter in my K3 to
2.8 KHz and listen to a CW signal at a 550 Hz pitch, then whatever I set
the DSP bandwidth to -- from 2.8 KHz down to 50 Hz -- I do not hear an
audio image (the signal on the 'other' side of zerobeat).

Having said that, if there were an S9+30dB signal above or below the
desired signal by 1.4 KHz, then it would activate the hardware AGC and
cause a gain reduction on the desired signal. In this case I would want
a narrower crystal filter.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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drewko

Re: Best CW Pitch???

In reply to this post by Don Wilhelm-4

Ok, I've recorded several sets of filter settings for different
sidetone/offsets, so now I can change them in about a minute. Doing
this shouldn't be a problem for the rig, right?

If you wanted to you could put one set of filters in the CW Normal
slots and another set in the CW Rev slots. I suppose for the CW Rev
filters you could put the BFO on the 'wrong' side of center and you
would then have two sets of filters, two different sidetone/offsets,
both CW Norm, right? Not sure I'd really want to do that; just
wondering.

73,
Drew
AF2Z

On Sat, 29 Sep 2007 16:33:53 -0400, Don W3FPR wrote:

>Drew,
>
>Like other things in life, one often must make compromises. That
>compromise would ideally be made based on your preferences and with
>knowledge of what is best for certain conditions.
>
>We know that low pitches are better for the brain to separate two
>different pitches (a signal in QRM), and we also know that very high
>speed CW operators like a higher pitch because it is easier to discern
>the code elements. If you belong to either group, your choice is
>obvious, but I believe for most, the compromise using the Elecraft
>default of 600 Hz makes sense - but you can change it for any reason if
>you have a desire to do that.
>
>I have heard that weak signal operators (i.e. EME) like to use a wide
>bandwidth, but I have not heard about a preferred pitch.
>
>73,
>Don W3FPR