[RFI] Urban noise

[Tom Thompson]

Jim,

What surprised me was the magnitude.  45 dB above the band noise is a lot!!

Tom  W0IVJ

On 2/12/2016 10:23 AM, Jim Brown wrote:
> On Thu,2/11/2016 7:23 PM, Tom Thompson wrote:
>> Yesterday, a friend of mine drove down a main street in the suburbs 
>> of Denver using a Perseus radio and a wide band antenna.  On the 20 
>> mile trip we experienced 45 dB of change in band noise due to various 
>> RFI sources.
>
> Was this a surprise?  If so, why? Certainly you must have been aware 
> of the proliferation of switch-mode power supplies and other noisy 
> electronics, some of it part of infrastructure for street signalling 
> and lighting, traffic cameras, etc. Those switch-mode power supplies 
> are part of virtually ALL modern electronics, whether internal or a 
> wall wart or a cord lump, they are used as battery chargers for 
> everything from power tools to mobility scooters. And they are used as 
> power supplies for low voltage lighting, including track lighting, 
> fancy architectural fixtures, and so on. The vast majority of this 
> crap is NOT suppressed and much of it lacks an FCC compliance sticker.
>
> All of this noise is radiated by attached wiring, both on the 120V 
> side and on the low voltage side.
>
> 73, Jim K9YC
>
>
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