[RFI] FCC Limits on Harmful Interference: Clarification

[EDWARDS, EDDIE J]

Kim is absolutely correct!  We do NOT want a measured level of interference to define "harmful interference".  

The level of RFI to a big gun DXer or contester is going to be something completely different than a 75 meter guy who only rag chews with local and regional guys on weekends in the winter or to a VHF-only guy on 6 & 2 meters.  

If they set a specific measured level, the DXer/Contester will be very unhappy, but the majority of hams might be just fine with it.  

Here's the FCC's Part 15.3 definition of Harmful Interference that can keep nearly all hams satisfied: 
(m) Harmful interference. Any emission, radiation or induction that endangers the functioning of a radio navigation service or of other safety services or seriously degrades, obstructs or repeatedly interrupts a radiocommunications service operating in accordance with this chapter. ( https://www.ecfr.gov/cgi-bin/text-idx?SID=e166a4ce09aa3e1d0025e4e6ae005023&mc=true&node=pt47.1.15&rgn=div5#se47.1.15_13 )

The part that applies to the Amateur Radio Service is: 
"...or seriously degrades, obstructs or repeatedly interrupts a radiocommunications service operating in accordance with this chapter." 

This applies equally to all ham radio operations at all frequencies (VLF to microwaves) used by the ham radio operator.  It also equally applies to aviation and commercial services as well.  And it applies to all part 15 devices from arcing or sparking power lines to unfiltered devices such as touch lamps or computers and everything in between.  

If the FCC gave a specific level, utilities would measure the noise and only fix noises to that specific level leaving many with harmful interference.  I would be unable to convince utility management to do anything more about it.  

So as this shows, we already have the best specific level of Part 15 RFI: Harmful Interference.  


73, de ed -K0iL
Ed Edwards

-----Original Message-----
From: RFI <rfi-bounces+eedwards=oppd.com at contesting.com> On Behalf Of Kim Elmore
>From what I've understood form Ed Hare, "harmful interference" is 
defined on a case-bay-case basis. I don't think we want a hard and fast 
limit, to be honest. What works in one case may be a disaster in another.

Kim N5OP

On 12/28/2019 7:49 PM, Tony wrote:
> All:
>
> I made the mistake of hitting send without editing so I apologize for 
> my previous post on radiated emission limits. As Ed Hare mentioned 
> numerous times, there are no FCC limits on radiated emissions below 30 
> MHz.
>
> What I meant to say was this:
>
> Ed mentioned that the FCC had taken action based on harmful 
> interference and I assumed it was based solely on the definition of 
> interference and not how it was generated i.e, radiated or conducted. 
> Hence, I asked how the FCC measures harmful interference.
>
> This seems logical because the term harmful interference would be 
> meaningless if the FCC only deems it as such if it's conducted and not 
> radiated -- it's either harmful or it's not.
>
> Or am I missing something?
>
> Tony -K2MO
>>
>>> On Dec 28, 2019, at 2:56 PM, Tony <dxdx at optonline.net> wrote:
>>>
>>> ???On 12/22/2019 6:19 PM, Hare, Ed W1RFI wrote:
>>>> the FCC has sent out many dozens of advisory letters to operators 
>>>> of various devices on the basis of harmful interference.
>>> Does anyone know what the FCC limits are on harmful interference 
>>> caused by radiated emissions with regard to HF and the amateur radio 
>>> service? Is the noise measured at the receiving station or is it?? 
>>> measured at some specified distance from the offending device?
>>>
>>> It would be interesting to know if the same FCC standards apply to 
>>> commercial and aviation services.
>>>
>>> Tony -K2MO