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(K3) APF and selected bandwidth

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RobertG

(K3) APF and selected bandwidth

When using the APF, does it make a difference which bandwidth has been
selected? Or in other words, does APF work better on top of a narrow or
wide bandwidth, or is selected bandwidth irrelevant? Thanks.
...robert
--
Robert G Strickland, PhD ABPH - KE2WY
[hidden email]
Syracuse, New York, USA
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Ken Arck

Re: (K3) APF and selected bandwidth

The narrower the bandwidth, the better signal to noise.

That should answer your question :-)

Ken

At 07:39 PM 10/15/2016, Robert G Strickland wrote:

>When using the APF, does it make a difference which bandwidth has
>been selected? Or in other words, does APF work better on top of a
>narrow or wide bandwidth, or is selected bandwidth irrelevant? Thanks.
>...robert
>--
>Robert G Strickland, PhD ABPH - KE2WY
>[hidden email]
>Syracuse, New York, USA
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
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Brian Hunt

Re: (K3) APF and selected bandwidth

In reply to this post by RobertG

On the other hand, when used in conjunction with NR a wider DSP BW is desirable since NR works on uncorrelated noise. Try:
BW= 700-1000 Hz,
NR= ~ 5-3
APF= ON
Great for pulling out weak signals on an uncrowded band. The NR settings of 5 and above mix processed and non-processed data so the APF has something to work on. My theory, anyway.

73,
Brian, K0DTJ

> On Oct 15, 2016, at 19:52, Ken Arck <[hidden email]> wrote:
>
> The narrower the bandwidth, the better signal to noise.
>
> That should answer your question :-)
>
> Ken
>
>
> At 07:39 PM 10/15/2016, Robert G Strickland wrote:
>> When using the APF, does it make a difference which bandwidth has been selected? Or in other words, does APF work better on top of a narrow or wide bandwidth, or is selected bandwidth irrelevant? Thanks.
>> ...robert
>> --
>> Robert G Strickland, PhD ABPH - KE2WY
>> [hidden email]
>> Syracuse, New York, USA
>>

ae5ka

Re: (K3) APF and selected bandwidth

I seem to recall a recommendation to use a 400 Hz bandwidth with APF. In my
own exerience, narrowing DSP bandwidth much below this does not seem to
help APF function and rather muddies it.

Chip
AE5KA

On Sat, Oct 15, 2016 at 11:44 PM, Brian Hunt <[hidden email]>
wrote:

> On the other hand, when used in conjunction with NR a wider DSP BW is
> desirable since NR works on uncorrelated noise. Try:
> BW= 700-1000 Hz,
> NR= ~ 5-3
> APF= ON
> Great for pulling out weak signals on an uncrowded band. The NR settings
> of 5 and above mix processed and non-processed data so the APF has
> something to work on. My theory, anyway.
>
> 73,
> Brian, K0DTJ
>
> > On Oct 15, 2016, at 19:52, Ken Arck <[hidden email]> wrote:
> >
> > The narrower the bandwidth, the better signal to noise.
> >
> > That should answer your question :-)
> >
> > Ken
> >
> >
> > At 07:39 PM 10/15/2016, Robert G Strickland wrote:
> >> When using the APF, does it make a difference which bandwidth has been
> selected? Or in other words, does APF work better on top of a narrow or
> wide bandwidth, or is selected bandwidth irrelevant? Thanks.
> >> ...robert
> >> --
> >> Robert G Strickland, PhD ABPH - KE2WY
> >> [hidden email]
> >> Syracuse, New York, USA
> >>
>
> ______________________________________________________________
> Elecraft mailing list
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briancom

Re: (K3) APF and selected bandwidth

Part of the problem with narrower bandwidths is making sure the signal
is at the APF peak.

I had fits trying to use APF with 200-400 Hz dialed in until I launched
Spectrogram and made sure the signal peak aligned with the APF peak.
Weak signals still show even when you have trouble hearing them. This
alignment helps with pulling them out. One can tune either the K3 shift
knob or K3 main tuning if it is set at 1 Hz steps.

Works every time.

Spectrogram can be collapsed to a small rectangle for this purpose an
permanently left on the display. HSDR also has a narrow bandwidth
display. Other spectrum display programs would work as well.

73 de Brian/K3KO

On 10/16/2016 13:03 PM, Chip Stratton wrote:

> I seem to recall a recommendation to use a 400 Hz bandwidth with APF. In my
> own exerience, narrowing DSP bandwidth much below this does not seem to
> help APF function and rather muddies it.
>
> Chip
> AE5KA
>
> On Sat, Oct 15, 2016 at 11:44 PM, Brian Hunt <[hidden email]>
> wrote:
>
>> On the other hand, when used in conjunction with NR a wider DSP BW is
>> desirable since NR works on uncorrelated noise. Try:
>> BW= 700-1000 Hz,
>> NR= ~ 5-3
>> APF= ON
>> Great for pulling out weak signals on an uncrowded band. The NR settings
>> of 5 and above mix processed and non-processed data so the APF has
>> something to work on. My theory, anyway.
>>
>> 73,
>> Brian, K0DTJ
>>
>>> On Oct 15, 2016, at 19:52, Ken Arck <[hidden email]> wrote:
>>>
>>> The narrower the bandwidth, the better signal to noise.
>>>
>>> That should answer your question :-)
>>>
>>> Ken
>>>
>>>
>>> At 07:39 PM 10/15/2016, Robert G Strickland wrote:
>>>> When using the APF, does it make a difference which bandwidth has been
>> selected? Or in other words, does APF work better on top of a narrow or
>> wide bandwidth, or is selected bandwidth irrelevant? Thanks.
>>>> ...robert
>>>> --
>>>> Robert G Strickland, PhD ABPH - KE2WY
>>>> [hidden email]
>>>> Syracuse, New York, USA
>>>>
>>
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
>>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

Robert .

Re: (K3) APF and selected bandwidth

I'm curious about others BW (width) setting on CW
If weak, really weak using 20 to 15 hz
Going narrower to 10 or 5hz setting doesn't seem to do much
Really helps on weak 160 signals, generally APF off

73 Robert W5AJ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of brian
Sent: Sunday, October 16, 2016 9:43 AM
To: [hidden email]
Subject: Re: [Elecraft] (K3) APF and selected bandwidth

Part of the problem with narrower bandwidths is making sure the signal is at
the APF peak.

I had fits trying to use APF with 200-400 Hz dialed in until I launched
Spectrogram and made sure the signal peak aligned with the APF peak.
Weak signals still show even when you have trouble hearing them. This
alignment helps with pulling them out. One can tune either the K3 shift
knob or K3 main tuning if it is set at 1 Hz steps.

Works every time.

Spectrogram can be collapsed to a small rectangle for this purpose an
permanently left on the display. HSDR also has a narrow bandwidth display.
Other spectrum display programs would work as well.

73 de Brian/K3KO

On 10/16/2016 13:03 PM, Chip Stratton wrote:

> I seem to recall a recommendation to use a 400 Hz bandwidth with APF.
> In my own exerience, narrowing DSP bandwidth much below this does not
> seem to help APF function and rather muddies it.
>
> Chip
> AE5KA
>
> On Sat, Oct 15, 2016 at 11:44 PM, Brian Hunt <[hidden email]>
> wrote:
>
>> On the other hand, when used in conjunction with NR a wider DSP BW is
>> desirable since NR works on uncorrelated noise. Try:
>> BW= 700-1000 Hz,
>> NR= ~ 5-3
>> APF= ON
>> Great for pulling out weak signals on an uncrowded band. The NR
>> settings of 5 and above mix processed and non-processed data so the
>> APF has something to work on. My theory, anyway.
>>
>> 73,
>> Brian, K0DTJ
>>
>>> On Oct 15, 2016, at 19:52, Ken Arck <[hidden email]> wrote:
>>>
>>> The narrower the bandwidth, the better signal to noise.
>>>
>>> That should answer your question :-)
>>>
>>> Ken
>>>
>>>
>>> At 07:39 PM 10/15/2016, Robert G Strickland wrote:
>>>> When using the APF, does it make a difference which bandwidth has
>>>> been
>> selected? Or in other words, does APF work better on top of a narrow
>> or wide bandwidth, or is selected bandwidth irrelevant? Thanks.
>>>> ...robert
>>>> --
>>>> Robert G Strickland, PhD ABPH - KE2WY [hidden email]
>>>> Syracuse, New York, USA
>>>>
>>
>> ______________________________________________________________
>> 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 Message delivered to
>> [hidden email]
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html Message delivered to
> [hidden email]
>

Elecraft mailing list

Re: (K3) APF and selected bandwidth

I chase very weak CW signals on 160M 80M and 6M many of which Iwould not have been able to hear unless I turned on the APF feature.
I have a 400kz filter as my narrowest CW filter and tune like this:
1) Zero beat exactly
2) Hold the XFIL/APF button 3) Narrow the width as far as it will go to .05 which I interpret as being 50hz 4) it might help to change tuning to 3 digits by taping the FINE button 5) Tune ever so carefully +/- a few hz and sometimes shifting slightly until the best signal is heard
A weak signal often pops right out of the noise, but be you will find there may be unpleasantringing, popping in the noise you might not like. Point is u can pull a signal out and work himwhen it would otherwise be impossible to copy.
73Dave N4DB K3s 10223

On Sunday, October 16, 2016 12:56 PM, Robert W5AJ Wood <[hidden email]> wrote:

I'm curious about others BW (width) setting on CW
If weak, really weak using 20 to 15 hz
Going narrower to 10 or 5hz setting doesn't seem to do much
Really helps on weak 160 signals, generally APF off

73 Robert W5AJ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of brian
Sent: Sunday, October 16, 2016 9:43 AM
To: [hidden email]
Subject: Re: [Elecraft] (K3) APF and selected bandwidth

Part of the problem with narrower bandwidths is making sure the signal is at
the APF peak.

I had fits trying to use APF with 200-400 Hz dialed in until I launched
Spectrogram and made sure the signal peak aligned with the APF peak.
Weak signals still show even when you have trouble hearing them. This
alignment helps with pulling them out. One can tune either the K3 shift
knob or K3 main tuning if it is set at 1 Hz steps.

Works every time.

Spectrogram can be collapsed to a small rectangle for this purpose an
permanently left on the display. HSDR also has a narrow bandwidth display.
Other spectrum display programs would work as well.

73 de Brian/K3KO

On 10/16/2016 13:03 PM, Chip Stratton wrote:

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delivered to [hidden email]

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Message delivered to [hidden email]

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Bill W4ZV

Re: (K3) APF and selected bandwidth

In reply to this post by RobertG

(BTW I wrote the following ~3 years ago before APF was changed from HOLD to TAP on DUAL PB):

##############################################################
I use APF virtually all the time and never use RIT, SHIFT, etc. Just HOLD DUAL PB to actuate APF and use the VFO to zero beat. COARSE (10 Hz) VFO steps is usually close enough but you can switch to FINE (1 Hz) if necessary for ultra weak signals. I also strongly endorse N6KR's suggestion below:

"I suggest setting the passband width to about 250-300 Hz when using APF."

This is extremely important since bandwidths too narrow will introduce additional ringing to the APF which already borders on ringing. I actually use a 200 Hz XFIL but set to actuate at DSP 400 Hz. With WIDTH set to 400 Hz, the signal first goes through the relatively broad (4.0 shape factor) 200 Hz XFIL, then a 400 Hz DSP and finally the narrow APF. This makes the cascaded XFIL/DSP seem more like 250 Hz, reduces ringing, still allows you to hear off-frequency callers (although attenuated) and helps your ears discriminate weak signals from noise by providing a wider background sample of noise.
#######################################################

The last phrase "helps your ears discriminate weak signals from noise by providing a wider background sample of noise" is key. Narrower bandwidths are not best for the human ear/brain...no matter what theory says about narrower bandwidths having better S/N.

73, Bill W4ZV