Propgtn Is my hump the same as your hump ?

[TAC4]

Probably not the best way to phrase it lol but over the years even when I was an SDR user I notice my noise floor was very low at 11970 Khz then rise like a large hump for a long time in the band, getting larger as I was tuning (down) in the band.

It did not matter what radio I used or antenna or even the time of day the hump is always there. Sorry I don't have a waterfall to show. This hump that starts around 11970 Khz sounds just like the noise floor no man made RFI at all.

So my question is do you have this same hump in that same location in the band ? I also wonder if this is a world wide (atmospheric) hump or just a local thing ?

 

[KB4MSZ]

Here is what I have with a 250' end fed long wire, and 5 MHz of bandwidth centered on 11.970 Mhz.

 

[sunwave]

There will always be "peaks and valleys" on a radio whether it be a SDR, portable, handheld or tabletop. Its all about the performance of whatever antenna is attached to the receiver and environment. I am using an 18ft center fed wire. Here is my "humps" aka "peaks and valleys". I use Winrad color pallette in SDRuno for visibility.

SR (sample rate) is at 10msps or 10MHz of spectrum centered on 40m ham.

 

[KB4MSZ]

What hump?

 

[TAC4]

What hump?

View attachment 169297

Ha ha

 

[TAC4]

Thanks guys, those water falls show no hump or even a
major drop off (cliff) at 11790 Khz so it must be local
atmospheric conditions.

 

[Boombox]

I've noticed such 'humps' in atmospheric noise over the years, just tuning through the spectrum on regular digital readout and analog tuned portables and comm rigs. It's very similar to what shows on the SDR screenshots above.