On 12/28/2018 4:54 PM, Simon wrote:
Hi K9YC,
Many thanks for the detailed analysis.
1. Sorry, I do not understand why u said, quoted, "Gauging by the FT8
signals centered around 7075 kHz, I'd call this QTH pretty noisy". This
is the FT8 band at 7074kHz, usb and wsjt-x decoded good copy of
traffic. Those are wanted ft8 signals.
I'm using their strength as a guide to the strength the noise sources I
identified.
Ft8 Traffic was busy, 4 decodes per 15 seconds cycle. Strongest signal
is 4 dB snr. Most are better than -4dB snr, rare one was weakest at -19
dB. From call sign, many are from Indonisia, Australia and new zealand,
4000km from Hong Kong sota qth. So, it was good received signal from
4000 to 6000km away. It was healthy signals.
That's not a lot of decodes -- I regularly decode several dozen signals
on each pass on the HF bands.
2. The sota site has no AC utility electricity and no street lamps, it
is a laws protected country park area where they preserve nature.
100 meters away is a public toilet with solar panel and pir triggered
led lighting, which should be off as there is likely no one in toilet.
Solar panel was zero output as it was dark, 30 minutes after sunset. No
charging pwm noise.
500 meters away, and blocked by hill profile, as 100 meter lower, is a
ranger office. Should be all person off duty at that time. Sure, there
may be some smps still running.
Up 150 meters, are two airport long range survilance radars, one
primary, one secondary radar, with Powerful smps inside. Radar range
about 700km for the hong kong fir, flight information region, from hong
kong to taiwan to philpines.
There is a residential estate, 500 homes, 30 floors buildings, 2 km
away, with all kind of smps inside, computer, fluroresent lighting, led
lighting, vfd motor drive for lift, etc.
It's hard to get away from noise. In essence, all of these noise sources
are added together to form the noise floor. To find a dead quiet band,
you almost need to be tens of miles from sources. One of the few times
I've encountered that was a county expedition for the California QSO
Party three years ago in a very remote part of Trinity National Forest.
No homes, no radio sites, nothing as far as the eye can see from our
site looking out from about 1,000 ft above the ground sloping away from us.
73, Jim K9YC
_______________________________________________
wsjt-devel mailing list
wsjt-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/wsjt-devel
