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[K3] Notch filter vs JT65?

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Don Putnick-6

[K3] Notch filter vs JT65?

There's a local ham who is also on JT65. He shows up as a big red splatter
on the waterfall. I used the K3's notch filter to remove him. He's gone but
now there's big red splatter to either side of the notch on the waterfall
and two wide peaks on the spectrum. K3, iMic soundcard, or JT65 signal
processing artifacts?
73 Don NA6Z
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Grant Youngman-2

Re: [K3] Notch filter vs JT65?

Rather than blame the K3, your sound card or “artifacts”, I’m going to stick my neck out and suggest he’s one of those guys that thinks everything works better when you crank the gain all the up …

How far away from you is he?

> On Aug 27, 2017, at 10:41 AM, Don Putnick <[hidden email]> wrote:
>
> There's a local ham who is also on JT65. He shows up as a big red splatter
> on the waterfall. I used the K3's notch filter to remove him. He's gone but
> now there's big red splatter to either side of the notch on the waterfall
> and two wide peaks on the spectrum. K3, iMic soundcard, or JT65 signal
> processing artifacts?
> 73 Don NA6Z
>

Grant NQ5T
K3 #2091, KX3 #8342

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Don Putnick-6

Re: [K3] Notch filter vs JT65?

He's really close - 2 miles. At that distance, any power would wipe out
JT65. I'm venturing to guess it's DSP artifacts. The humps are too smooth
and asymmetric to either side of the notch in the spectrum display.

On Sun, Aug 27, 2017 at 8:00 AM, GRANT YOUNGMAN <[hidden email]>
wrote:

> Rather than blame the K3, your sound card or “artifacts”, I’m going to
> stick my neck out and suggest he’s one of those guys that thinks everything
> works better when you crank the gain all the up …
>
> How far away from you is he?
>
> Grant NQ5T
> K3 #2091, KX3 #8342
>
>
>
>

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Bob McGraw - K4TAX

Re: [K3] Notch filter vs JT65?

A couple of things to check. Be sure the Line Output from the radio is not set to high such that it is driven into distortion.

Also check the computer CODEC gain isn't too high and it being driven into distortion. This is set in Windows Sound device Recording Level.

Also make sure the ALC is ON and handling the signal. Perhaps some attention on the input of the receiver is in order.

The receiver Noise Blanker should be OFF.

Bob, K4TAX

Sent from my iPhone

> On Aug 27, 2017, at 12:53 PM, Don Putnick <[hidden email]> wrote:
>
> He's really close - 2 miles. At that distance, any power would wipe out
> JT65. I'm venturing to guess it's DSP artifacts. The humps are too smooth
> and asymmetric to either side of the notch in the spectrum display.
>
> On Sun, Aug 27, 2017 at 8:00 AM, GRANT YOUNGMAN <[hidden email]>
> wrote:
>
>> Rather than blame the K3, your sound card or “artifacts”, I’m going to
>> stick my neck out and suggest he’s one of those guys that thinks everything
>> works better when you crank the gain all the up …
>>
>> How far away from you is he?
>>
>> Grant NQ5T
>> K3 #2091, KX3 #8342
>>
>>
>>
>>
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Wes Stewart-2

Re: [K3] Notch filter vs JT65?

In reply to this post by Don Putnick-6

If it's on, turn off flatten and see what happens.

Wes N7WS

On 8/27/2017 7:41 AM, Don Putnick wrote:
> There's a local ham who is also on JT65. He shows up as a big red splatter
> on the waterfall. I used the K3's notch filter to remove him. He's gone but
> now there's big red splatter to either side of the notch on the waterfall
> and two wide peaks on the spectrum. K3, iMic soundcard, or JT65 signal
> processing artifacts?
> 73 Don NA6Z

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Dave Sublette

Re: [K3] Notch filter vs JT65?

In reply to this post by Bob McGraw - K4TAX

Well, to state the obvious — just transmit during the same time slot that the other station transmits….

K4TO

> On Aug 27, 2017, at 2:07 PM, Bob McGraw K4TAX <[hidden email]> wrote:
>
> A couple of things to check. Be sure the Line Output from the radio is not set to high such that it is driven into distortion.
>
> Also check the computer CODEC gain isn't too high and it being driven into distortion. This is set in Windows Sound device Recording Level.
>
> Also make sure the ALC is ON and handling the signal. Perhaps some attention on the input of the receiver is in order.
>
> The receiver Noise Blanker should be OFF.
>
> Bob, K4TAX
>
>
> Sent from my iPhone
>
>> On Aug 27, 2017, at 12:53 PM, Don Putnick <[hidden email]> wrote:
>>
>> He's really close - 2 miles. At that distance, any power would wipe out
>> JT65. I'm venturing to guess it's DSP artifacts. The humps are too smooth
>> and asymmetric to either side of the notch in the spectrum display.
>>
>> On Sun, Aug 27, 2017 at 8:00 AM, GRANT YOUNGMAN <[hidden email]>
>> wrote:
>>
>>> Rather than blame the K3, your sound card or “artifacts”, I’m going to
>>> stick my neck out and suggest he’s one of those guys that thinks everything
>>> works better when you crank the gain all the up …
>>>
>>> How far away from you is he?
>>>
>>> Grant NQ5T
>>> K3 #2091, KX3 #8342
>>>
>>>
>>>
>>>
>> ______________________________________________________________
>> 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
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>
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Bob McGraw - K4TAX

OT - Notch filter vs JT65?

In reply to this post by Grant Youngman-2

And he may be running a linear amplifier which is not tuned correctly.
I find frequently that hams really do not know how to tune a linear
amplifier and operate it so it is "linear". The result is splatter
among other artifacts. As they say, there's more that 's wrong than
correct.

73
Bob, K4TAX

On 8/27/2017 10:00 AM, GRANT YOUNGMAN wrote:
> Rather than blame the K3, your sound card or “artifacts”, I’m going to stick my neck out and suggest he’s one of those guys that thinks everything works better when you crank the gain all the up …
>
> How far away from you is he?
>
>

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Jim Brown-10

Re: [K3] Notch filter vs JT65?

In reply to this post by Bob McGraw - K4TAX

All very good advice.

BUT - how close is he? How much bandwidth is he occupying? How many dB
down at how many Hz from the center of his signal?

AND VERY important -- K1JT has repeatedly advised to NOT to any
filtering ahead of WSJT-X, because the phase shift associated with the
filter degrades decoding.

I have locals in the range of 5-20 miles from me and both they and I are
running power (me, a KPA500). Depending on what direction each of our
antennas are pointed, the "red" can be pretty wide. But that does NOT
mean that WSJT-X cannot decode signals in that red zone! Further, the
colors in the waterfall are absolute level at input to WSJT-X. ANY
signal will have sidebands. If, for example, he's 40 over S9 (not
unusual at two miles), even the cleanest of radios with modulation will
be S9 within 200-300 Hz of his signal.

73, Jim K9YC

On 8/27/2017 11:07 AM, Bob McGraw K4TAX wrote:
> A couple of things to check. Be sure the Line Output from the radio is not set to high such that it is driven into distortion.
>
> Also check the computer CODEC gain isn't too high and it being driven into distortion. This is set in Windows Sound device Recording Level.
>
> Also make sure the ALC is ON and handling the signal. Perhaps some attention on the input of the receiver is in order.
>
> The receiver Noise Blanker should be OFF.

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Elecraft mailing list

Re: [K3] Notch filter vs JT65?

I agree with Jim, very strong signals will wash out a waterfall but have very little effect on decodes. I have decoded extremely weak signals only a fewHz away from strong signals. I leave filters at 2700hz and NEVER use anotch filter on any WSJT modes.
73, Dave N4DB

On Sunday, August 27, 2017, 6:41:03 PM EDT, Jim Brown <[hidden email]> wrote:

All very good advice.

BUT - how close is he? How much bandwidth is he occupying? How many dB
down at how many Hz from the center of his signal?

AND VERY important -- K1JT has repeatedly advised to NOT to any
filtering ahead of WSJT-X, because the phase shift associated with the
filter degrades decoding.

I have locals in the range of 5-20 miles from me and both they and I are
running power (me, a KPA500). Depending on what direction each of our
antennas are pointed, the "red" can be pretty wide. But that does NOT
mean that WSJT-X cannot decode signals in that red zone! Further, the
colors in the waterfall are absolute level at input to WSJT-X. ANY
signal will have sidebands. If, for example, he's 40 over S9 (not
unusual at two miles), even the cleanest of radios with modulation will
be S9 within 200-300 Hz of his signal.

73, Jim K9YC

On 8/27/2017 11:07 AM, Bob McGraw K4TAX wrote:
> A couple of things to check. Be sure the Line Output from the radio is not set to high such that it is driven into distortion.
>
> Also check the computer CODEC gain isn't too high and it being driven into distortion. This is set in Windows Sound device Recording Level.
>
> Also make sure the ALC is ON and handling the signal. Perhaps some attention on the input of the receiver is in order.
>
> The receiver Noise Blanker should be OFF.

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