[RFI] Dancing Carriers

[k1ttt.dave at gmail.com]

Signals like that which move up and down are generally something like
harmonics of switching power supply or variable speed motor or some other
non locked frequency digital system, that is, something that doesn't rely on
a specific clock frequency like computers, tv's, modems, ethernet, etc
require.  Power supplies drift with temperature, line voltage, or load.  The
step functions you see may be because the sdr only processes the spectrum a
few times a second so they appear to stay the same for a short time then
jump a bit as the next set of samples is plotted and the signal has moved
into the next fft column range.

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: telnet://k1ttt.net:7373


-----Original Message-----
From: RFI <rfi-bounces+k1ttt=arrl.net at contesting.com> On Behalf Of
alex at kr1st.com
Sent: Monday, December 19, 2022 14:57
To: rfi at contesting.com
Subject: [RFI] Dancing Carriers

Hi there,

 

I'm trying to figure out what is generating these "dancing carriers" on 2m:

 

https://youtu.be/gKA0P2c-034

 

I see them om on 6m and 1.25m as well. Has anyone come across this before
and can share a hint at what may be causing this? Since the signature looks
to be easily recognizable to someone who ran across this before I thought
I'd ask on this list. 

 

I recorded this a few minutes ago using a RSP2Pro using SDR Console and a
CX-333 antenna at just 20ft or so. I have the gain on the RSP2 very low as
to rule out any overloading. The beacon you are hearing is W3CCX/b on
144.300 MHz. The carriers are not modulated and are there 24/7. They are
118.5 kHz apart. I also see it on the IC-9700 with a DCI-146-4H bandpass
filter so I don't think it's some mixing product caused by a strong out of
band signal. 

 

73,

--Alex KR1ST

 

 

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