Hi Mark,
Great advice from others on here and I was not going to respond to your
post but I finally broke down, so here goes.
About 10 years ago I experienced RFI from a VFD (variable frequency drive)
that generated a very similar pattern when it started up using a soft start
routine. The drive was running a large exhaust fan in a commercial kitchen
at a senior living apartment complex. In my case the VFD carrier frequency
was 4KHz but 3KHz is likely another common carrier frequency and if the RFI
now being discussed is being generated by a VFD it appears it might be
using a carrier frequency of 3KHz (assuming I’m interpreting the spectrum
display properly). This is all a wild guess and it really does not matter
what’s generating the RFI as you first need to use good direction finding
techniques to identify what property the RFI is originating from.
I would first document the on and off schedule/behavior of this RFI
(including possible weather dependency) as others have mentioned and also
identify what bands you hear it on and then use DF gear to determine what
property the RFI is originating from and then you can work with the
property owner to determine what device is really generating the RFI.
You need to keep an open mind when tracking down RFI and while it’s fun to
guess what might be generating the RFI it’s really not helpful guessing
besides determining if the RFI might be power line noise or not as that
helps determine what equipment to bring as what DFing techniques might be
helpful (example: HF or HF and VHF).
73,
Don wd8dsb
On Tue, Nov 14, 2023 at 11:55 AM Facility 406 <
facility_406@bruteforcedevelopment.com> wrote:
> Received the following message through another forum this morning.
> Peculiar RFI I've not seen, or heard before.
>
> Ideas?
>
> Original poster email address is:
>
> mark@spacetubes.com
>
> Original message below:
>
>
>
> Wondering if anyone has seen any RFI that looks like this.
>
>
> https://spacetubes.com/DX/Digital.RFI.Lower.AM.Band.Start--2023.Nov.14--sdkaz--perseus.mp4
>
>
> https://spacetubes.com/DX/Digital.RFI.Lower.AM.Band.End--2023.Nov.14--sdkaz--perseus.mp4
>
> The first link shows it starting up, then it goes like that for a while
> (sometimes a long time - half an hour or more), then it ends like what's
> shown in the second link,
>
> Then it can be quiet for a random amount of time, before it starts up
> again.
>
> Mark Pettifor
> Goshen, IN -- en71ao
> _______________________________________________
> 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
|