[RFI] LED Street lights

Thu Aug 24 11:03:06 EDT 2023

Hi Jim,

Respectfully, as far as I know, a SDR does not qualify as an exotic 
device anymore...

Your premise seems to be that if an exotic device is needed to spot the 
RFI, it is not RFI.  I would tend agree with that, but that is not what 
the OP asked, he asked what he should be listening for, and he 
specifically mentioned the lack of an Spectrum Analyzer, which indicates 
he is interested in something beyond what his K3, or a handheld SW radio 
provides.  Hence my suggestion for the SDR approach, it provides him a 
wide spectrum device, showing RFI in a wide spectrum view, and can be 
done from his home, while at the same time showing him the start wand 
end times for ALL his RFI.

I never look for RFI I don't hear first in my ham receiver.  If it is 
not on my day to day rig, (or someone else's if I am assisting them), it 
is not RFI.  Yet another reason for using the SDR first.  If I suspect 
something may be causing RFI, but don't hear it, I pull the SDR out and 
look for it.  Wandering around with a SW radio in hand won't help me 
locate something I can't hear, or don't know what to look for.  That 
approach will confuse me because I don't know what to look for...

Standing at the base of an RFI filled pole, listening with a hand held 
SW radio will let you hear all the RFI on that pole at once, not just a 
street light.  However, if you set up an SDR, and record what is 
happening, showing that the RFI covers a few MHz, (only the SDR can do 
that), and you have the time frame of the RFI, (tying it to the 
streetlight start/end, via the SDR waterfall), you stand a FAR better 
chance of getting your RFI located and correctly IDed.

You have also taken a recording of the problem, and can show it to the 
owner of the device, all from the comfort of your home, not wandering 
the streets with a SW radio, hoping you are in the right place at the 
right time to hear some RFI source you have never heard before.

That is why I suggested the use of the SDR, as opposed to walking around 
with a hand held SW rig, it shows FAR more than a simple hand held 
receiver ever will.

BTW, you used quotes of the words, 'spot the noise' in your post, I cant 
seem to locate that quote in my post, can you point me at that quote 
please?

My RFI hunting practice is not to spot noise, (I am looking because I 
have already spotted an RFI issue with my normal HF rig), but to 
characterize the RFI noise before I go looking.  Much the same as the 
power companies do with their Radar Engineering equipment.

The first thing the power company does is to connect to your home 
antenna, and take a snapshot of the RFI, then go looking.  That way they 
know what to look for.

I stand a far better chance of following the right noise source around, 
by not relying just on my ears alone to pattern match.

I am really good a pattern matching via ear, I can pick structure out of 
noise instantly, and remember it, I did for years before I started using 
an SDR, however, using an SDR is FAR better than my ears will ever be.

When I null a source, I see several MHz of RFI null at the same time, 
while I also see several MHz, of RFI NOT null, if I know what I am 
looking for I can spot the RFI instantly, and without ambiguity.

Again, please take this respectfully, as it is intended.

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 8/23/23 17:17, AA5CT wrote:
> Hmmm ... if an exotic receive apparatus is required to 'spot the noise', 
> how serious could the noise really be?
> 
> First tier inspection ought to be a portable SW radio brought to the 
> pole and a quick survey made of the ham bands.
> 
> Just an observation of the situation on my part.
> 
> de AA5CT Jim
> 
> --------------------------
> 
> On Wednesday, August 23, 2023, 6:09:14 PM GMT-5, Dave (NK7Z) 
> <dave at nk7z.net> wrote:
> 
> 
> Hi,
> Your best option is to spend a hundred bucks and get an RSP 1A from
> SDRPlay, any SDR will work, but the RSPPlay RSP1A works very well for a
> tool to evaluate RFI issues..  Then see:
> 
> https://www.nk7z.net/sdr-rfi-survey-p1/ 
> <https://www.nk7z.net/sdr-rfi-survey-p1/>
> 
> 73, and thanks,
> Dave (NK7Z)
> https://www.nk7z.net <https://www.nk7z.net>
> ARRL Volunteer Examiner
> ARRL Technical Specialist, RFI
> ARRL Asst. Director, NW Division, Technical Resources
> 
> On 8/23/23 15:57, Eric Rosenberg wrote:
>  > Yesterday my city (Washington, DC) replaced our neighborhood’s street 
> lights with LED ones. I suspect they will be installed in the alley on 
> the other side of my city (140 ft x 40 ft) lot.
>  >
>  >
>  >
>  > I didn’t get a chance to take a picture of the one on the pole in 
> front of my house, nor have I checked out ow noisy they are, if at all.
>  >
>  >
>  >
>  > I hope to o do that in the next week or so (been very busy at work).
>  >
>  >
>  >
>  > I don’t have a pan adapter or and test gear other than  m y K3.
>  >
>  >
>  >
>  > That being said,  what should I be listening for?  I nothing else, I 
> assume they’ll be brighter.
>  >
>  >
>  >
>  > Thanks & 73,
>  >
>  >
>  >
>  > Eric W3DQ
>  >
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