A few years back, ARRL did some measurements of the ambient noise levels at
typical HF stations. The results were presented at a TIA T1E1.4 committee
meeting (VDSL standards).
The paper is available for download at:
http://www.arrl.org/~ehare/vdsl/vdsl-tia.htm
To put it into perspective, S9 is -73 dBm (50 microvolts across 50 ohms) and
an S unit is assumed to be 6 dB. (This is the old Collins "standard." There
is also a Region 1 standard that defines the S unit this way on HF.)
It is relatively easy to make the measurments with a calibrated signal
generator, a hybrid coupler and a calibrated audio voltmeter. They can also
be done with a calibrated receiver. If anyone has done any actual
measurements, please post them here. With permission, I can compile them,
along with additional measurements that ARRL will be doing over the ocoming
months, and make them available on the ARRL web site. If anyone would like
to do such measurements, I can provide more details on how to do the
testing.
When I get back to the office tomorrow, I will post some additional info
from the NTIA IONCAP/WINDOWS program (along with the URL to download it.)
73,
Ed Hare, W1RFI
ARRL Lab
-----Original Message-----
From: Pete Smith
To: rfi@contesting.com; topband@contesting.com
Sent: 2/28/2001 09:51 AM
Subject: [RFI] RFI levels
I'm wondering what the consensus is on a "reasonable" noise level for a
rural location on 80 meters in daytime, with no thunderstorm activity
within groundwave range. Right now, in CW wide position, my S-meter is
registering between S5 and S7 in the quietest direction, and S9 +10 in
the
noisiest. Switching in the cascaded 400 Hz filters, noise level is S5
in
the worst direction, and not registering on the S meter in the quietest.
I know about how unreliable and non-standard S meters are, particularly
at
the bottom of their range, but want to get some idea of what I should be
shooting for.
73, Pete N4ZR
Contesting is!
The World Contest Station Database
is waiting for your input at
http://www.qsl.net/n4zr
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