One could use the 24/7 NCDXF beacons. BeaconSee does a very nice job of
displaying the beacon signals on the computer screen and will
automatically write the image to a file at intervals you specify. If
you display the beacons on all 5 bands from 20 to 10, it takes 2 hours
to fill the display with, I think, 8 measurements at 15 minute intervals
for each beacon on each band. The result is qualitative, rather than
quantitative, no numbers, but high noise levels show up quite dramatically.
This doesn't help, of course, for bands below 20m. It does have the
advantage of being really cheap and easy to implement, provided your rig
can be interfaced to a computer. How cheap? Free if you don't want to
automatically file the images. Paying a registration fee ($30?) allows
auto save. http:\\www.ip.pt/coaa
Given that you'll be receiving from beacons all over the world on many
bands, an all-band vertical is probably the best antenna to use. I use
a CC R-5. Works great.
The usual disclaimer applies.
73 de Jim Smith VE7FO
Jim wrote:
Martin,
It would seem to me that some 'standard' QSO
contacts need to be run (scheduled) and the
S/N ratio measured and 'recorded', maybe on a
daily or weekly basis, demonstrating a negative
slope, to fit in with Ed's comment and philosoply
I think.
'Harmful Interference' could then be seen numerically
how it impacts actual QSOs via 'degraded S/N ratios'.
By contrasting 'normal' signal levels and 'noise' signal
levels in the bands as opposed to absolute signal
strengths of 'noise' alone the 'harmful' aspect could
be emphasized (however, absolute signal levels
are/would always be useful for engineering purposes).
Using a slightly different methology, perhaps some
statistics of 'average' received signal strengths from
various stations on various bands could be 'established'
as 'figures' for comparison against measured, 'absolute'
noise levels later on, and from which a determination,
after examination of the recorded data, one could deem
that certain noise 'levels' are indeed deemed to be
'harmful'.
One could record the activity on a couple of the more
popular HF nets, including the county hunters net, and
this collected data could be used as a baseline figure
as the resident, normal, expected in-band amateur
activity against which 'absolute' noise figures could be
compared. And the 'noise' need not be active at the
same time as the nets are; the two can be compared
at any convenient time, one against the other.
Just my two cents this evening ...
Jim de WB5WPA
----- Original Message -----
From: "Martin Ewing" <martin@aa6e.net>
To: <rfi@contesting.com>
Sent: Friday, November 05, 2004 2:44 PM
Subject: [RFI] RFI / Band Monitor
Folks,
I have been working on a semi-realtime band monitor
system, and there are some early results at
www.aa6e.net/aa6e/rfi/monitor.html. I am recording
what happens on 40 & 20 M in 2 kHz channels in my
particular environment.
Why would we want to do this?
-Learn a little about propagation conditions vs solar
activity, etc.
-Pick up (and record) RFI problems
-Get a baseline, pre-BPL deployment
-Too much hardware, software, and time available ;-)
Ed Hare actually suggests it's a bad idea to make
baseline recordings if you want to proceed against the
power companies with a BPL complaint. The logic is
perverse, but he may be right. See Ed's famous URL:
http://www.arrl.org/~ehare/bpl/measurements.html .
But as a frustrated radio astronomer and programmer, I
couldn't resist. Already, I see some interesting
"UFOs", but they're probably somewhere in my house.
The process needs to be automated more, and I will
have to decide if it's worth trying to make a
long-term record (months/years).
How could this stuff be made more useful?
73, Martin, AA6E
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