[RFI] How very interesting...

[Larry Benko]

Dave,

No Sh-t Sherlock!!  This was a comment a guy I used to work with would 
say when someone touted something that was blatantly obvious!

I have also felt this way for a few years.  I built an active hi-Z 
preamp on a magnetic base with a 4' whip and drive around with a Perseus 
receiver.  Looking at a wide chunk of spectrum was the only way W0IVJ 
and myself were able to show Century Link how much VDSL2 radiates (an 
SDRPlay ws used for the VDSL2 stuff).  We drove up a street with a 
Century Link engineer in the back seat of the car and pointed out 
exactly which houses had DSL service. Without getting out of the car we 
were correct about 80% of the time and sometimes were off by one house.

Driving through a commercial or industrial area is especially 
interesting as the noise floor varies easily 1000x (30dB) within a 
several hundred feet.

Hope others will realize that this is an extremely good way to track 
down RFI while being stealthy.  A non-directional antenna will never 
replace a directional one but is an additional tool.

73,

Larry, W0QE


On 8/25/2016 4:59 AM, Dave Cole wrote:
> Hi,
>
> Just thought I would share this with the collective group, because it
> seems so interesting...
>
> I took an SDRPlay, and set it to something like 2 MHZ wide, then pointed
> that at the 40 meter band, and set it loose recording in graphic form,
> across a very long time frame to get an overview of my RFI environment
> across time.  It is attached...  All times are GMT, and the graph starts
> at around 2:30 PM local time here in Oregon.
>
> I expected interesting results, but got something far more fascinating,
> and busy than I thought.  Much structure is visible in this...  Being
> able to visualize huge swaths of spectrum over time is so informative.
>
> I have been trying to get a tool for generating an RFI survey of an
> area, and this seems to fit the bill well.
>
> In the near future, I will be moving to AZ, and I think I will strap
> this setup onto a laptop, put it in my car, and connect it to my mobile
> antenna for Low Bands, to survey the area I am considering moving
> into...
>