[RFI] Help Identifying RFI

[Dave Cole (NK7Z)]

Jim (WPA),

Respectfully, if you have not used an SDR for location you should give 
it a try before you write it off.

I have everything you mentioned-- and more with my SDR setup...  Almost 
all SDR packages come with a built in O-Scope display of the audio one 
is tuned to, all SDR packages allow one the ability to listen, and in 
any mode, although I use AM 99.9% of the time.  All SDRs gives me the 
ability to see the RFI across MHz, to KHz of spectrum, this helps in 
locating exactly what source I am looking for.  I can move higher in 
frequency as I approach with no changed in gear, just a different 
antenna...  Works like a champ to locate RFI.

I can see individual RFI sources drop and increase as I rotate the loop, 
that lets me follow one single source.  It's amazing to rotate the loop, 
and watch the ONLY the RFI source I am looking for dip, while the others 
are not dipped...  I take a bearing, and it is just like the old days, 
take a few more, then start looking at a map, then get closer, and use 
the Yagi at 100 MHz, using the same radio...

How did we do DFing before SDR, a Yaesu FT-817ND, several different 
sized loops, a Yagi, and maps, just the same as I use the SDR.

The SDR is tons faster.  You should give it a try-- really!  I have done 
both methods extensively, and the SDR makes it a lot simpler and faster 
for me.  I still wander around with headphones on listening to the RFI, 
I just get more data by looking at the SDR display which helps me in 
locating RFI.

Dave
NK7Z
http://www.nk7z.net

On 09/25/2017 03:41 PM, JW via RFI wrote:
> Well, maybe one's ears have gone bad limiting one's ability to note the noise characteristics.
> 
>  From the SDR spectrum displays I've seen one CANNOT note whether the carrier is AC line modulated or not - just a pip showing on the screen..
> 
> Real definitive. I find an oscilloscope observing the AM detected output of the receiver in the time domain to be more useful. I even use LINE TRIGGER to verify it is AC line related.
> 
> Also, if you'll  note, wideband arcing AC line sources simply cause an SDR's baseline to rise across the entire viewing range and without actually LISTENING one cannot know if the SDR is showing anomalous overload indications or broandand impulse noise. .
> 
> Give me a device I can use my ear with any day of the week .. ...
> 
> (How did we ever DF noise sources before SDR burst onto the scene? To me, many SDR aficionados are just looking for a 'mission' they can fill in this regard and have little to no other exposure to DF techniques.)
> 
> de Jim WB5WPA,
> 
> 
> 
>        From: Jim Brown <jim at audiosystemsgroup.com>
>   To: rfi at contesting.com
>   Sent: Monday, September 25, 2017 5:09 PM
>   Subject: Re: [RFI] Help Identifying RFI
>     
> On 9/25/2017 6:56 AM, JW via RFI wrote:
>> Massive overkill IMO to stress the need for an SDR to accomplish this task.
> 
> Not really -- any decent spectrum display can be a BIG help in chasing
> and identifying RFI.
> 
> 73, Jim K9YC
> 
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