Not an arcing source.
Get BlueMail for Android
On Jan 9, 2020, 3:39 PM, at 3:39 PM, Don Kirk <wd8dsb@gmail.com> wrote:
>Hi Jim,
>
>I looked at that RFI noise in sync with 60 hertz video you wanted me to
>look at using my soundcard scope, and attached is what I captured.
>Very
>obvious 120 hertz.
>
>I also just took another look at Kens audio recording using another
>recording he supplied me which gave me more time to listen without
>human
>voice on top of the noise, and I do in fact see 120 hertz bursts (not
>60 as
>I initially reported), but not narrow bursts like the recording you had
>me
>look at.
>
>Either way I believe the info we have supplied Ken should help him
>track
>down the source.
>
>Thanks,
>Don (wd8dsb)
>
>On Thu, Jan 9, 2020 at 12:43 PM AA5CT <jwin95@yahoo.com> wrote:
>
>> Don,
>>
>> Can you feed this video's audio into the analysis software and
>> see what it gives? As can be clearly seen there is a 'pulse' for
>> each 1/2 cycle of the AC waveform, or two pulses for a complete
>> cycle of 60 Hz mains.
>>
>>
>> https://www.youtube.com/watch?v=C-S5ef-Ne6Y
>>
>>
>> Also note that the first 'breakdown' shifts around, while the second
>> breakdown is fairly constant; this is due to materials or the
>structure
>> involved in the area of where the arc forms.
>>
>>
>> Note: Scope triggered from local "Line" voltage, also shown overlaid
>> as a single cycle as seen on the scope's CRT.
>>
>>
>> de AA5CT
>>
>> .
>> .
>>
>> On Thursday, January 9, 2020, 10:46:02 AM CST, 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)
>> _______________________________________________
>> RFI mailing list
>> RFI@contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
>>
>_______________________________________________
>RFI mailing list
>RFI@contesting.com
>http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|