On 12/28/2018 11:29 PM, Simon wrote:
Is there a source of data for natural and man made noise, as pick up
by an isotopic antenna (or dipole which will be about 2dB higher) in
dBm value, either
a) based on 'fixed paper model" as page 5 of ITU-R document,
R-REC-P.372-13-201609
b) actual measurement or 'daily' prediction of 'atmospheric conditions'
I'm vaguely aware that bodies like ITU or IEEE have published stuff like
this, but I'm not aware of who and where. Further, that's wildly
variable by location, propagation conditions, and many other factors.
Further, and most important, data that's decades old won't reflect the
proliferation of SMPS, other power-handling systems,
microprocessor-based systems, and so on. And there are now "backhaul"
transmissions on CATV and DSL systems (they bring user data to the
system) in the 3.5-6 MHz range that have massive leakage problems. I
strongly suspect that the mechanism by which this trash escapes the CATV
system is what we EMC specialists in the pro audio world call "The Pin
One Problem." See RFI tutorials on my website for a discussion of the
mechanism.
Does the natural noise level vary with air temperature, season,
Power line noise is well known to vary with humidity
geographic location, sun spot, etc.?
Of course. It is, for example, generally true that in a quiet location,
propagated noise will increase by 10 dB or more when the band is open.
I was under the impression that the HF (unlike VUHF) noise floor will
be some what higher and the HF receiver sensitivity cannot be use to
its lowest level, specification is 0.3uV, -117dBm for the RSP1A. I
used decimation 8, so may be noise floor is a little bit lower.
Presumably, it will be 10 dB SINAD and -127dBm noise floor
All of that is quite dependent on the antennas used. It's quite common
for serious operators on the 160M band to have dedicated receive
antennas. I have two reversible Beverages, 550 and 500 ft long, and I
have a pair of VE3DO loops spaced 5/8 wave (about 350 ft). Beverages
have fairly high output, the loops far less.
The SOTA test show noise floor at -130dBm and the HF receiver can work
at its lowest level as in the case of VUHF. The SDRPlay RSP1A is
calibrated to show real dBm value.
Again, that number is highly dependent on the antenna. Here's a nice
piece of work that I think you might find useful. It addresses exactly
the issues I think you're trying to get at.
http://wwrof.org/webinar-archive/receiving-antenna-metrics-with-examples/
There are a lot of tutorials and applications notes on my website that
you may find helpful. k9yc.com/publish.htm
BTW -- if you're Simon Brown, I'd like to thank you for all the fine
software you've contributed to the ham community over the years.
73, Jim K9YC
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