GE Don,
Yes I hear them. They aren't like a SMPS or arcing RF audio which is
pretty easy to identify but it is not quite white noise either.
I am running the system with the gain turned down and the automatic gain
control turned off. There's no limiting occurring. I also moved the
center frequency of the sweep around by adding odd numbers to the base
frequency (for example, 4.077Mhz) and the repetitive signals remain at
the same frequency indedpendent of the center frequency chosen.
I have found hash generated by the Dell laptop but it is generally above
10MHz. I looked at the 2MHz to 6MHz band, where this hash is most
evidence using two SDRs (an RSP1 and an RSPro2) on a business class Dell
desktop machine and laptop.
I have not scanned the spectrum while away from the QTH yet. That's next
on the list. I did power down the house at the service panel, removed
the battery from the fiber modem, and checked to be sure that any
battery powered computing machinery was turned off. The results before
and after doing so were the same.
73 Bill K7WXW
______________
brevity is beautiful.
Don Kirk wrote on 12/21/18 6:01 PM:
Hi Bill,
You show these repetitive signals on your SDR setup, but need to make
sure they are real.
1) Do you actually hear each of these repetitive signals on your HF
rig versus the SDR receiver?
2) If you reduce the SDR system gain, do the spikes suddenly disappear
(do they suddenly appear when you increase your SDR gain past a
certain point)? It's very common that when SDR gain exceeds a
particular value that spurious emissions appear in the SDR display.
3) If you go outside away from your house with your SDR system, are
these signals still present?
Note: I run a portable SDR DF system with a lap top, and the battery
operated lap top (a Dell high end lap top) generates lots of RF hash
that can be detected when my portable DF antenna is within a few feet
of the laptop.
Don (wd8dsb)
On Fri, Dec 21, 2018 at 5:19 PM bill K7WXW <K7WXW@qrpdx.org
<mailto:K7WXW@qrpdx.org>> wrote:
GA All
My noise reduction project continues. I have been working on noise
sources in my house
but need some help with what seems to be an external source.
For data capture, I am using an RSPro2 and RSP-SAS spectrum analyzer
software, running on a
battery powered laptop. The RSPro2 SDR is connected, via window
line, to
my main antenna through the
high Z port.
I ran four series of data capture:
SDR with nothing on any antenna port (establishing a base line,
looking
for artifacts).
SDR with 2' of window line connected to the high z port
SDR connected to my main antenna, house power and fiber modem power on
SDR connected to my main antenna, house power and fiber modem
power off
Each set includes captures at 3.25, 7.15, 10, 14.15, 18.00, 21.00,
24.50, 28.50,
and 29.50 MHz, all using the same SDR and SA settings.
As expected, some of the noise is produced inside my house (modems,
switching power
supplies, etc). I am cleaning that stuff up by switching out
supplies,
adding ferrites
and so on.
But there is a lot of noise between 2 and 6 MHz that is present
whether
my QTH is powered
up or down. That's what I want to focus on in my request for
help. I've
posted six
screen captures that show what is happening, which can found at this
dropbox link:
https://www.dropbox.com/sh/zncdt66fdnqb2my/AADSHrTgcV5nJOTVgj1zm6vua?dl=0
The first four show a 500KHz span around 3.25MHz. The first three are
all with
house power on, the last with power off:
003 K7WXW RFI 122018
- window line feed, 2' (evening)
001 K7WXW RFI 122118-1
- window line feed, 2' (morning)
001 K7WXW RFI 122118-2 (AGC was accidentally switch on for this
set of
captures)
- 130' doublet (main antenna)
002 K7WXW RFI 122118-3
- 130' doublet (main antenna, power off)
The last two two show a wider span, with house power off:
015 K7WXW RFI 122118-3 (5MHz sweep, centered at 4.05MHz)
- 130' doublet (main antenna, power off, fiber power on)
016 K7WXW RFI 122118-3 (5MHz sweep, centered at 4.05MHz)
- 130' doublet (main antenna, power off, fiber power off)
Whatever the source, it is powerful enough to pick up with a 2'
section
of window line
connected to an SDR in my basement. It doesn't change when I power
down
the house and
fiber modem. It appears to be going 24 hours a day, though I haven't
gotten up in the
middle of the night to confirm that. Any ideas where to start looking?
thx and 73 Bill K7WXW
______________
brevity is beautiful.
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