OT noise on 17m

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OT noise on 17m

RobertG
Can someone help me understand the "noise" on 17m - and elsewhere -
right now? It repeats every 17kc, very strong. Perhaps some sort of over
the horizon radar? Is it general or just something in my neighborhood?
Thanks much.
...robert
--
Robert G Strickland, PhD ABPH - KE2WY
[hidden email]
Syracuse, New York, USA
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Re: OT noise on 17m

ab2tc
Hi,

None of it here in Camillus (a suburb west of Syracuse).

AB2TC - Knut
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Re: OT noise on 17m

GM4JJJ
In reply to this post by RobertG
Bob,

Most probably a switched mode power supply somewhere locally, almost everything we see repeated at regular frequency intervals like that are harmonics of SMPS. Often up to VHF unfortunately :-(

Have you tried switching off the house breaker and listening on batteries to be sure it isn't self inflicted?

It could be anything from a mobile phone charger to a grow light ballast.

73 from David GM4JJJ

> On 11 Mar 2016, at 14:41, Robert G Strickland <[hidden email]> wrote:
>
> Can someone help me understand the "noise" on 17m - and elsewhere - right now? It repeats every 17kc, very strong. Perhaps some sort of over the horizon radar? Is it general or just something in my neighborhood? Thanks much.
> ...robert
> --
> Robert G Strickland, PhD ABPH - KE2WY
> [hidden email]
> Syracuse, New York, USA
> ______________________________________________________________
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Re: OT noise on 17m

Jim Brown-10
In reply to this post by RobertG
Yet another example of a switch-mode power supply.  Here's a preliminary
version of k9yc.com/KillingReceiveNoise.pdf  that might help.

73, Jim K9YC


On Fri,3/11/2016 6:41 AM, Robert G Strickland wrote:
> Can someone help me understand the "noise" on 17m - and elsewhere -
> right now? It repeats every 17kc, very strong. Perhaps some sort of
> over the horizon radar? Is it general or just something in my
> neighborhood? Thanks much.
> ...robert

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Re: OT noise on 17m

HankP
In reply to this post by RobertG
The stuff I have run into that is in the 16 to 18 khz range includes
furnace /air conditioner  motor controls and  washing machines.

Of course those are intermittent which is also a clue- although
there are some furnace/A/C blowers that stay on at low speed all
the time for circulation.  

If you have a P3 - decrease the span  and most of the newer stuff
at certain parts of the cycle will actually be several spikes in
each group of noise.

Hank K7HP



 


----- Original Message -----
Can someone help me understand the "noise" on 17m - and elsewhere -
right now? It repeats every 17kc, very strong. Perhaps some sort of over
the horizon radar? Is it general or just something in my neighborhood?
Thanks much.
...robert
--
Robert G Strickland, PhD ABPH - KE2WY
[hidden email]
Syracuse, New York, USA
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Re: OT noise on 17m

KENT TRIMBLE
In reply to this post by RobertG
Robert . . .

*Space Weather News for March 11,
2016*<http://Spaceweather.us11.list-manage.com/track/click?u=0c5fce34d5ca05f64a13d085d&id=e2ac0b4915&e=f3feb8fb27>http://spaceweather.com 
<http://Spaceweather.us11.list-manage.com/track/click?u=0c5fce34d5ca05f64a13d085d&id=e2ac0b4915&e=f3feb8fb27>
*

UNEXPECTED GEOMAGNETIC STORM: *  Earlier today, the outskirts of a CME
previously expected to miss Earth instead /hit/. The impact sparked a
G2-class geomagnetic storm and bright auroras around the Arctic
Circle.   At the time this alert is being written, the storm is still in
progress.   Visit Spaceweather.com
<http://Spaceweather.us11.list-manage.com/track/click?u=0c5fce34d5ca05f64a13d085d&id=7913f15e9f&e=f3feb8fb27>
for updates.


73,

Kent  K9ZTV


On 3/11/2016 8:41 AM, Robert G Strickland wrote:
> Can someone help me understand the "noise" on 17m - and elsewhere -
> right now? It repeats every 17kc, very strong. Perhaps some sort of
> over the horizon radar? Is it general or just something in my
> neighborhood? Thanks much.
> ...robert

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Re: OT noise on 17m

GM4JJJ
Coincidental I think hi. Yes Aurora on 144 MHz here this afternoon and the magnetometers showing the impact too.

73 from David GM4JJJ

> On 11 Mar 2016, at 19:01, KENT TRIMBLE <[hidden email]> wrote:
>
> Robert . . .
>
> *Space Weather News for March 11, 2016*<http://Spaceweather.us11.list-manage.com/track/click?u=0c5fce34d5ca05f64a13d085d&id=e2ac0b4915&e=f3feb8fb27>http://spaceweather.com <http://Spaceweather.us11.list-manage.com/track/click?u=0c5fce34d5ca05f64a13d085d&id=e2ac0b4915&e=f3feb8fb27> *
>
> UNEXPECTED GEOMAGNETIC STORM: *  Earlier today, the outskirts of a CME previously expected to miss Earth instead /hit/. The impact sparked a G2-class geomagnetic storm and bright auroras around the Arctic Circle.   At the time this alert is being written, the storm is still in progress.   Visit Spaceweather.com <http://Spaceweather.us11.list-manage.com/track/click?u=0c5fce34d5ca05f64a13d085d&id=7913f15e9f&e=f3feb8fb27> for updates.
>
>
> 73,
>
> Kent  K9ZTV
>
>
>> On 3/11/2016 8:41 AM, Robert G Strickland wrote:
>> Can someone help me understand the "noise" on 17m - and elsewhere - right now? It repeats every 17kc, very strong. Perhaps some sort of over the horizon radar? Is it general or just something in my neighborhood? Thanks much.
>> ...robert
>
> ______________________________________________________________
> 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]
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Re: OT noise on 17m

EUGENE GABRY
In reply to this post by HankP
Here's noise from my neighbors new washing machine (Samsung).  http://www.slickpic.com/users/GeneGabry/albums/N9TFHamStationPhotos/?wallpaper&viewer#11792105 
Repeats about every 17Khz. From about 20Mhz-22.5Mhz. Most of all the RF pollution in my neighborhood generates garbage on 15m. Have not seen any yet of 17m. At least the washing machine garbage only lasts for about 60 minutes two to three times a week (when I'm in the shack on 15m).
 
Just wait until buck/boost DC-DC converters and switchers are deployed more prolific at 1Mhz and higher. Company I work for makes the line choke and power inductors used in those switchers. They are worse noise generators than the lower frequency switchers 50khz-500khz. It's only going to get worse :(
 
Gene, N9TF 

From: "HankP" <[hidden email]>
To: "Robert G Strickland" <[hidden email]>
Cc: "Elecraft" <[hidden email]>
Sent: Friday, March 11, 2016 12:46:56 PM
Subject: Re: [Elecraft] OT noise on 17m

The stuff I have run into that is in the 16 to 18 khz range includes furnace /air conditioner  motor controls and  washing machines.

Of course those are intermittent which is also a clue- although
there are some furnace/A/C blowers that stay on at low speed all
the time for circulation.  

If you have a P3 - decrease the span  and most of the newer stuff
at certain parts of the cycle will actually be several spikes in
each group of noise.

Hank K7HP



  


----- Original Message -----
Can someone help me understand the "noise" on 17m - and elsewhere -
right now? It repeats every 17kc, very strong. Perhaps some sort of over
the horizon radar? Is it general or just something in my neighborhood?
Thanks much.
...robert
--
Robert G Strickland, PhD ABPH - KE2WY
[hidden email]
Syracuse, New York, USA
______________________________________________________________
Elecraft mailing list
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Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html 
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separating RFI from band noise, PX3

Greg Troxel-2
In reply to this post by Jim Brown-10
Jim Brown <[hidden email]> writes:

> Yet another example of a switch-mode power supply.  Here's a
> preliminary version of k9yc.com/KillingReceiveNoise.pdf  that might
> help.

I see you mention a 10 dB increase in levels between band closed and
band open, with the notion that if you don't see that, you have too much
local noise.  That makes a lot of sense for bands like 15m.  I don't
quite follow how one can use that rule of thumb on 6m.  For 80m,
presumably it should be quieter in the day.

I've been looking at various bands with a PX3.  Certainly my outside
(80m dipole ish) antenna is quieter than my attic dipole, but some times
it's pretty close -- presumably that's when band noise dominates.

I wonder if it's possible to have any quantitative norms.  For example,
looking at the waterfall on 30m with a 50 kHz span, and ref of -110 dBm,
I'm seeing a lot of black pixels with a fair number of dark blue.  There
are a few solid lines that are obviously interference.  And I see some
short-duration broadband pulses (horizontal lines).  So I think I have
some issues, while others might find that better than usual.

Clearly some noise sources are obvious on the panadaptor.  But most of
what I'm seeing is not obvious.  In the end I suspect that trying to
decide if I have local noise by making measurements is not going to work
or be all that useful.  (Certainly measuring with power off makes sense,
and the open-vs-closed band levels is something I'll probably try to
really measure.)

Also when using the PX3, I realize that the levels can be interpreted in
two ways.  For signals narrower than the bin size, it seems that one
should read the level as the power in the bin and hence the signal.  But
for broad noise that is much bigger than bins, I think one should be
thinking in terms of dBm/Hz.  In other words, choosing a 5x narrower
span doesn't change the level of a carrier, but it lowers broadband
noise 5x.  So referring to "-100 dBm" seems to require giving the span
(or really the bin size, if one is comparing to non-Elecraft
panadaptors).

73 de n1dam
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Re: separating RFI from band noise, PX3

Jim Brown-10
On Fri,3/25/2016 4:29 PM, Greg Troxel wrote:
> Jim Brown <[hidden email]> writes:
>
>> Yet another example of a switch-mode power supply.  Here's a
>> preliminary version of k9yc.com/KillingReceiveNoise.pdf  that might
>> help.
> I see you mention a 10 dB increase in levels between band closed and
> band open, with the notion that if you don't see that, you have too much
> local noise.  That makes a lot of sense for bands like 15m.  I don't
> quite follow how one can use that rule of thumb on 6m.

Most noise sources get weaker with increasing frequency, so there tends
to be less noise on 10M and 6M because there's so there's much less to
propagate.

> For 80m, presumably it should be quieter in the day.

Yes, and on 160M too.

> I wonder if it's possible to have any quantitative norms.  For example,
> looking at the waterfall on 30m with a 50 kHz span, and ref of -110 dBm,
> I'm seeing a lot of black pixels with a fair number of dark blue.

Most spectrum analyzers are best used by setting  the threshold at the
noise floor, and with averaging set to the maximum for the amplitude
display. This will cause random noise to average out, making signals and
correlated noise stand out.  Do NOT use waterfall averaging.  Also, use
reasonable settings for SCALE -- I use 24 dB for general operating to
find signals on a dead band, etc. and 42 dB for contests where many
stations are running high power into big antennas. The only time I use a
wider scale than that is when I want to look at sidebands of a
transmitter working into a dummy load.

>   There
> are a few solid lines that are obviously interference.  And I see some
> short-duration broadband pulses (horizontal lines).  So I think I have
> some issues, while others might find that better than usual.
>
> Clearly some noise sources are obvious on the panadaptor.  But most of
> what I'm seeing is not obvious.  In the end I suspect that trying to
> decide if I have local noise by making measurements is not going to work
> or be all that useful.  (Certainly measuring with power off makes sense,
> and the open-vs-closed band levels is something I'll probably try to
> really measure.)

Don't view this as a "measurement," but rather as a graphic view of your
RF environment.  Also, the settings noted above can help.

> Also when using the PX3, I realize that the levels can be interpreted in
> two ways.  For signals narrower than the bin size, it seems that one
> should read the level as the power in the bin and hence the signal.  But
> for broad noise that is much bigger than bins, I think one should be
> thinking in terms of dBm/Hz.  In other words, choosing a 5x narrower
> span doesn't change the level of a carrier, but it lowers broadband
> noise 5x.  So referring to "-100 dBm" seems to require giving the span
> (or really the bin size, if one is comparing to non-Elecraft panadaptors).

Yes, this is generally true, and the P3 can be set to automatically
change the scale to compensate when changing the bin size (scan width).
I don't remember if the PX3 firmware has that feature. But we don't care
all that much about absolute levels unless we're measuring something,
and when chasing noise, we're usually not measuring (except, of course,
for seeing how much we've suppressed a noise source by applying a fix).
But none of this logic applies -- we don't care about absolute levels,
we only want to know if our fix helped and how much.

73, Jim K9YC
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