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Trying to get to grips with the KDSP2 Filter

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Ray G3XLG

Trying to get to grips with the KDSP2 Filter

I am the 2nd owner of my K2 and have so far largely "ignored" the DSP filter but I thought I'd look into it further following my poor performance in a recent RTTY contest where some contacts were difficult but eventually OK and others were unable to decode my signals at all.
So far I have found the DSP filter settings currently in the K2 are as follows:
SSB
S1. .00 2.9
S2. .20 .2.5
S3. .30 .1.9
S4. .30 .1.6
Which I understand show that the denoiser is not currently activated, the notch is on and the other figures are the lower & upper cutoff frequencies in kHz.
CW
CF1 nr
CF2 nr
CF3 nr
CF4 nr
So it appears my DSP is not active on CW?
RTTY
r1 LPA.SS
r2 2.5 .1.0
r3 2.2 .30
r4 1.0 .20
I think this shows the centre frequencies of 1 to 2.5kHz & the width of 0.2 to 1.0kHz with filters r2, r3 & r4?

My questions are:
- why would the CW filters not be active & what does "nr" mean?
- what are typical DSP settings for RTTY, and are the ones in use OK?
- any other comments re these settings?

Still learning about this rig!
73
Ray, G3XLG

Ray G3XLG

Re: Trying to get to grips with the KDSP2 Filter

On CW I've just found that toggling the RCL button shows the following settings:

C.1 LPA.SS
C.2 .60 .80
C.3 .60 .30
C.4 .60 .10

73
Ray, G3XLG

Ray G3XLG

Ken Alexander-2

Re: Trying to get to grips with the KDSP2 Filter

In reply to this post by Ray G3XLG

Hi Ray,

I'm not an expert on the DSP, but my K2 has one and I'm happy with it.
To answer your questions:

1. The CW filters, like the SSB and RTTY filters are activated by using
the AFIL button on the front panel. nr = noise reduction I think the
DSP filter comes already configured, although I'm not positive about
that because I didn't buile mine either. Hopefully, some smarter person
will jump in and help. Regardless, you can cownload a copy of the KDSP2
manual from the Manuals and Downloads section of the Elecraft website.
It will tell you how to configure and use the filter.

2. The settings shown are perfectly good. The manual explains what
everything means. My interpretation is that the left hand number is the
frequency where the low pass filter kicks in and the right hand number
is the bandwidth...1 kHz for general uncrowded conditions and 200 Hz
during contests when the band is packed with signals.

3. The noise reduction works well on CW signals, although it softens
them somewhat, which some people don't like. But it does get rid of a
lot of noise! There are several "strengths" to which the noise
reduction can be set. I've always found the lowest setting to be the
best but that's a personal preference. Noise reduction isn't available
with the RTTY filters because it degrades the signal too much and makes
decoding difficult.

Definitely download yourself a copy of the manual!

Happy New Year,

Ken Alexander
VE3HLS

On 03/01/2012 6:47 AM, Ray G3XLG wrote:

> I am the 2nd owner of my K2 and have so far largely "ignored" the DSP filter
> but I thought I'd look into it further following my poor performance in a
> recent RTTY contest where some contacts were difficult but eventually OK and
> others were unable to decode my signals at all.
> So far I have found the DSP filter settings currently in the K2 are as
> follows:
> SSB
> S1. .00 2.9
> S2. .20 .2.5
> S3. .30 .1.9
> S4. .30 .1.6
> Which I understand show that the denoiser is not currently activated, the
> notch is on and the other figures are the lower& upper cutoff frequencies
> in kHz.
> CW
> CF1 nr
> CF2 nr
> CF3 nr
> CF4 nr
> So it appears my DSP is not active on CW?
> RTTY
> r1 LPA.SS
> r2 2.5 .1.0
> r3 2.2 .30
> r4 1.0 .20
> I think this shows the centre frequencies of 1 to 2.5kHz& the width of 0.2
> to 1.0kHz with filters r2, r3& r4?
>
> My questions are:
> - why would the CW filters not be active& what does "nr" mean?
> - what are typical DSP settings for RTTY, and are the ones in use OK?
> - any other comments re these settings?
>
> Still learning about this rig!
> 73
> Ray, G3XLG
>
>
> -----
> Ray G3XLG
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Trying-to-get-to-grips-with-the-KDSP2-Filter-tp7146478p7146478.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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>

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Ken Alexander-2

Re: Trying to get to grips with the KDSP2 Filter

In reply to this post by Ray G3XLG

I don't know why C.1 would say LPA.SS. It sounds like something hasn't
been set correctly. The other settings look OK. .60 means the filter
is centered on 600 Hz and the number to the right is the width of the
filter in kHz, where .80 would be 800 Hz and .10 would be 100 Hz (for
contests, etc.)

73 - Ken

On 03/01/2012 7:05 AM, Ray G3XLG wrote:

> On CW I've just found that toggling the RCL button shows the following
> settings:
>
> C.1 LPA.SS
> C.2 .60 .80
> C.3 .60 .30
> C.4 .60 .10
>
> 73
> Ray, G3XLG
>
> -----
> Ray G3XLG
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Trying-to-get-to-grips-with-the-KDSP2-Filter-tp7146478p7146503.html
> Sent from the Elecraft mailing list archive at Nabble.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
>
>

Ray G3XLG

Re: Trying to get to grips with the KDSP2 Filter

Thanks Ken & others who replied directly. I do have a copy of the KDSP2 manual & the KSB2 manual which are helpful and I now understand about "nr" on the CW filters.
But I still cannot find any recomended DSP filter settings for Data modes like RTTY or PSK31.
73
Ray, G3XLG

Ray G3XLG

Don Wilhelm-4

Re: Trying to get to grips with the KDSP2 Filter

Ray,

Think about how you are going to operate with data modes, and how you
have the RTTY filter set aligned (or will align it) - that will tell you
how to set the KDSP2 RTTY parameters.
If you will always use the full SSB filter width passband when using
digital modes, perhaps the RTTY filters that are set as default are OK
for you.
My recommendation is that you set the RTTY IF filters to widths of OP1,
1.00, 0.70, and 0.40. Set the passband for the OP1 filter the same as
you have for SSB, and center the passband for the more narrow filters at
1000 Hz.
Then set the center frequency of the KDSP2 filters to 1000 Hz.

In use, tune the desired signal to the vicinity of 1000 Hz in the
waterfall display so you can switch in the narrow IF filters and/or the
DSP filters to reduce QRM.

Why choose 1000 Hz for the center (you might ask) - well, the K2 BFO has
enough range to allow that frequency, but not much higher. Also, MMTTY
has a mark frequency setting of 910 Hz that works with that center
frequency.

73,
Don W3FPR

On 1/4/2012 10:13 AM, Ray G3XLG wrote:

> Thanks Ken& others who replied directly. I do have a copy of the KDSP2
> manual& the KSB2 manual which are helpful and I now understand about "nr"
> on the CW filters.
> But I still cannot find any recomended DSP filter settings for Data modes
> like RTTY or PSK31.
> 73
> Ray, G3XLG
>
> -----
> Ray G3XLG
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Trying-to-get-to-grips-with-the-KDSP2-Filter-tp7146478p7150770.html
> Sent from the Elecraft mailing list archive at Nabble.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
>