Don, I am very appreciative of you time and insight! Tonight we’re going out
with a Kx3 and 160m loop, hopefully we can find it this time.
With the AM radio we found a few nearby options to check first. We also found
other really noisy areas 2 miles away, but we will start close by.
I will keep you posted. While you already did some analysis, here’s my first
take of the audio which has about 4 seconds of no speech at the beginning. For
the trained ear you will also hear a few pulses at the start which are part of
4 pulses heard every 2 minutes On the nose. But that’s another project.
https://m.youtube.com/watch?v=r98vONfZGH4&feature=youtu.be
Regards , Kenny K2KW
> On Jan 9, 2020, at 11:45 AM, Don Kirk <wd8dsb@gmail.com> wrote:
>
>
> Hi Ken,
>
> Using 3 different audio software tools, I come up with a frequency of 60
> Hertz, not 120 Hertz. Typically power line noise has bursts at a frequency
> of 120 hertz (arcing each half of the sine wave).
>
> If it really is not power line noise which I suspect it's not, you will
> probably have a somewhat easier time locating it. It appears you have a good
> idea what direction it's coming from assuming the gain of the beverages are
> similar to each other. If so I would say the noise is from the East North
> East. If it were me I would use a portable tuned loop with portable preamp
> and portable HF receiver that would allow me to hear the noise just outside
> the house of KC4D, and then I would use the null (or peak) of the tuned loop
> to guide me right to the source while heading in the East North East
> direction (I consider this method a form of infinite triangulation because as
> you walk you continue to use the null of the loop to guide your direction of
> travel), I would reduce receiver gain or install attenuation as I get closer
> to the source so that I could still detect the null as I rotate the loop. In
> my experience you should be able to narrow in on this noise within 15 to 30
> minutes of walking. Most folks probably are not willing to invest in a
> preamp (buying or building one).
>
> The problem is that overhead power lines can radiate the signal, so you need
> to stay away from the power lines as much as possible. When this is the
> case, I then do true triangulation by going to different locations away from
> power lines to get headings, and then I plot the headings on Google Earth to
> see where they intersect.
>
> You should probably be able to hear this noise with a portable AM broadcast
> band radio too, and you might be able to just use the built in loop stick
> antenna to guide you to the source (using the null and peak method) but if
> you can't throw in attenuation as you get close you might have some
> difficulty when you get very close to the source, but I would certainly try
> this method. When you get right next to the source you might be able to hear
> it up on 136 MHz AM (if you have a police scanner this would be a tool you
> might try as the aviation band on the radio will provide AM reception), but
> this is probably not even necessary but might be very helpful in confirming
> you have located the source.
>
> If you want to assume it could be a street light (I see a lot of street
> lights on the main roads near KC4D), and you know the approximate time the
> noise shows up each day, I would listen on my cars AM radio while parked out
> on the side of these roads to see if I could catch the noise coming on when
> the lights turn on (observing both street lights and house lights, etc.).
> This assumes you are able hear the noise (a lot of new car radios have such
> good noise blankers that you can't hear this type of noise).
>
> There are a lot of other tools I use such as portable SDR receiver, but again
> that's normally more than most folks want to mess with for a one time
> situation.
>
> I would recommend driving the streets up to an approximate 1 mile radius and
> note the noise level during the day and during the night, and note where the
> noise was horrible at night but not during the day (this might be the very
> first thing I would try to do to isolate the problem while keeping things
> simple for you).
>
> Everyone has their own technique, and you need to work with whatever tools
> you can easily obtain.
>
> Keep us posted.
> Don (wd8dsb)
>
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