[RFI] Listen to a Sample of what Plasma TV RFI Sounds Like

[Tom Thompson]

Thanks, Rob...really helpful!!

Tom

On 4/7/2014 2:22 PM, Rob Atkinson wrote:
> There are a few variables you need to be aware of with reception of
> PTV RFI.  It sounds different depending on whether or not you are
> listening with or without a BFO.  It also depends on the passband of
> the rx.  Another factor is the distance between the set and the rx
> antenna.  More broadly, the frequency, because PTV RFI on the low HF
> bands sounds different from what you get on 15 meters.
>
> I've done some investigating on this.  PTV RF is a complex broad
> modulated signal that has many components and changes with the video
> signal.   If the set is tuned to a live sports event, there will be a
> lot of rapidly modulated RFI because the picture is constantly
> changing.  In my case, I listened to the recordings of PTV signals and
> thought I had some other problem because what I was receiving didn't
> sound like the PTV RFI mp3 recordings on-line.  Then I went to a few
> consumer electronics outlets with a portable SW BC receiver and walked
> around the plasma TVs on display.  Again, I thought I was not hearing
> what I I was hearing at home, but it turned out that the display TVs
> were all set up to show these videos of scenic vistas such as mountain
> valleys with the camera slowly panning from left to right.  Since that
> is an almost static video signal, the RFI generated did not have the
> pulsing rapidly modulated sound I heard at home.  Then a few started
> showing something like a football game and I began to hear exactly the
> noise I heard on my receivers in the shack.
>
> So you have to be careful.  If you don't think you are hearing PTV in
> your shacks, get a portable shortwave receiver (they are useful for
> other things around the station anyway) and take it to a store like
> Best Buy and walk around the TV sets on display and listen up close.
> some of the RF coming from the sets doesn't travel as far so in my
> tests, a distant set sounds different from one up close.
>
> 73
>
> Rob
> K5UJ
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