Hi Stephanie,
Sorry for the following long text in regards to your question about what
utility companies typically use, but believe some of it directly addresses
your question.
Radar Engineers is the company that makes RFI detection tools that's used
by most utility companies. Their model 243 is the device utility companies
typically will use to capture the RF signature of RFI encountered at a hams
QTH and they can store the signature and then go out looking for hardware
that generates a signature that matches the signature they stored. The
model 243 is not cheap (see below), so some utility companies might not own
one, and if it's a large utility company it might reside with someone in
their company many miles or states away. You can check out the Radar
Engineers website to see other RFI detection tools they also make. I also
show the price for their model 251 which is the parabolic ultrasound dish
they make that many utility companies use.
Current list price follows:
Model 243.........$6,700.00 plus shipping
Model 251.........$3,650.00 plus shipping
The only time a parabolic ultrasound dish should be used (in my opinion) is
after the pole generating the RFI has been located using VHF/UHF detection
gear, as you can almost always hear some kind of acoustic noise being
generated by hardware on a pole when using ultrasound if you look hard
enough (based on my limited experience with ultrasound gear), but the real
question is what pole is generating the noise that is causing the
interference at your QTH. One time when working with Duke Energy we tested
out their Radar Engineers parabolic dish and we could detect acoustic noise
to some extent on just about every pole we listened to in a string of
poles, but there was only one pole generating RFI up on VHF/UHF in this
string of poles and it turned out to be the source of RFI at my QTH.
I never contact a utility company until I have identified the faulty pole
using VHF radio direction finding gear, and then I leave it up to the
utility company to find the defective device on the pole.
The model 243 offers two different modes of operation, but it appears the
only mode that folks use operates as an oscilloscope looking at AM
demodulated baseband audio (Fred at Radar Engineers calls this "O'Scope"
mode versus "Spectrum mode" which he said also looks at the AM demodulated
signal). Based on my questioning of Radar Engineers, the horizontal axis
is indeed time and it represents a total of 20 msec with the vertical axis
being amplitude (20 msec allows them to capture a full cycle of the 60 Hz
power and then some). The model 243 is a narrow band receiver which you
dial in the frequency of interest, and then it demodulates the signal and
the built in oscilloscope displays the demodulated audio in the time
domain. I have had a hard time getting any additional details from Radar
Engineers regarding the architecture of the model 243 but the info they
provided offered a pretty good clue about their system. I have been
testing various SDR receiver software packages to duplicate what the model
243 sees, and believe I have been able to accomplish this with limited
success but that's a long story for another day.
In my opinion you really can do as good if not better than someone at the
utility company using their model 243 if you have a portable VHF AM
receiver with a good portable directional antenna (like a 4 element Yagi)
along with attenuators you can place in line (good to have 10 dB, 20 dB and
30 dB of attenuation available and a few times I have even needed 40 dB of
attenuation). As you get very close to the faulty pole you often need to
introduce 20 or 30 dB of attenuation in order to pinpoint the faulty pole.
I typically can hear arcing pole hardware up on 136 MHz when within 0.2
miles of the pole, but sometimes as far away as 0.8 miles as an example. I
first use portable HF direction finding gear to get me close enough to the
point where I can start hearing the RFI up on 136 MHz, and I often can hear
arcing power pole hardware from 1 or 2 miles away when using my portable HF
radio direction finding gear.
Hope I have answered your question, and then some.
73,
Don (wd8dsb)
On Fri, Sep 10, 2021 at 10:42 PM Stephanie WX3K via RFI <rfi@contesting.com>
wrote:
> All
>
> I live near the territory boundary of two utilities. My work with PP&L has
> fruitful and they have been very cooperative in resolving RFI issues i
> would report to them over the years.
>
> I have been struggling with MetEd for the same powerline noise for at
> least 5 years now. I recently got their attention again and reopened a new
> work order. I spoke to their tech today and learned they have been
> replacing cut-outs and repairing resistive connections. All good but my RFI
> issue continues mostly driven by drier windier weather conditions, the RFI
> swamps the 25-150 MHz spectrum.
>
> https://www.dropbox.com/s/ekn6xpl0960qrm7/IMG_9711.MOV?dl=0
>
>
> There are old bell type insulators on poles near this suspected line area.
> I consistently request they replace those problematic antiquated bell
> insulators that are notorious for RFI issues. They(MetEd) seem to avoid
> this. With my work with PP&L, replacing those bell insulators have
> completely resolved those reported issues. The techs from MetEd use their
> ultrasonic detectors to find issues but it is my impression these bell type
> insulators do not show up as issues when they look around with their
> ultrasonic detectors. True statement ? How does one convince a utility to
> actually listen to the RF spectrum for issues ? Is there a specific model
> spectrum analyzer that the utilities tend to use to scan for RFI ???
>
> Stephanie WX3K
>
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