[RFI] Guidance on finding noise?

[Dave Cole]

Here is a link to the SDR as a site survey tool pages:

https://www.nk7z.net/sdr-rfi-survey-p1/

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist
ARRL Asst. Director, NW Division, Technical Resources

On 1/12/20 10:53 AM, Jim Brown wrote:
> On 1/12/2020 10:14 AM, Lee STRAHAN wrote:
>>   The point to all this is try looking at the noise with a SDR radio 
>> that should give you a wider bandwidth picture.
> 
> RIGHT! It is quite likely that the noise K2KW and crew are chasing is 
> NOT generated by the power system, but rather some electronic or power 
> control device in a home or business. Traditional methods used to "pin 
> point a pole" make no sense for this kind of noise, which is why I keep 
> on saying "LOOK AT THE SPECTRUM."
> 
> The traditional methods that ARE applicable are what Lee describes and 
> loop antennas, in both cases connected to 1) an RX with a spectrum 
> display (best) or 2) a portable RX using a loop antenna that tunes to 
> the frequency(ies) where you hear the noise. For example, the broad 
> coverage RX in my Kenwood TH-F6A talkie uses an internal loopstick below 
> 10 MHz; the antenna input can be manually switched between that loop and 
> the SMA connector.  That's the upside; the downside is that it's not 
> very sensitive, so you have to be either pretty close to the source or 
> an external loop needs a preamp.
> 
> Another very important point -- virtually all noise generated by the 
> power system is IMPULSE NOISE that is the result of arcing, and it looks 
> like horizontal lines on a fast waterfall. Electronic noise, including 
> that generated by power-handling and control equipment like motor 
> controllers, industrial equipment, and switch=mode power supplies, looks 
> like humps on a spectrum display and slightly "squiggley" trails of 
> those humps on a waterfall.
> 
> A study of NK7Z's website is quite worthwhile. I also strongly STUDYING 
> my own application note. k9yc.com/publish.htm
> 
> Bottom line -- audio frequency spectrum and o-scopes are the WRONG tools 
> for anything but impulse noise, and a spectrum display is the RIGHT tool 
> for electronic noise.
> 
> 73, Jim K9YC
> 
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