Topband: Skimmer calibration

[Guy Olinger K2AV]

We were talking about validating or debunking people's RX experience
at the shore in various relationships to the edge of salt water.  And
the anecdota included just about any signal around, on whatever path
and whatever TX takeoff angle, not just the signals of a few specific
TX stations.

Contests would create a maximum number of stations, where signals on a
pair or trio of identical RX antennas get reported by a pair or trio
of skimmer RX. A test grouping could consist of one antenna were over
salt water or at edge, another 500 meters off shore, and another well
inland but within 50 km. This would assess the same situations as
anecdotal reports, and create enough paired or tripled data to
identify differences greater than 2 or 3 dB. It is possible that a
single contest might generate 10,000 groupings of over a thousand
stations, from the very weak to the quite strong.

What will be missing in a recent contest's worth of data apparently is
the over salt water data, perhaps a few within 500 meters, and the
rest. I don't know of current RBN nodes in the first two categories.
They serve the spotting network's users well by not reporting signals
at water's edge that a lot of people might not be able to hear.

It is one thing to RX at exotic sites with short vertical antennas,
and quite another to transmit there, with transmit grade antennas.

An RX setup, would use a common vertical, include a power source, RX
and CPU and blue tooth or 811g to connect, in a sealed box. The base
of each vertical would be 8 feet and use for each box a technology
chosen from the RX short vertical techniques.

Each setup would be calibrated with a milliwatt source to a very short
standard antenna at 100 meters distance to calibrate the band-is-dead
background noise. These could be transmitting during during the
contest as a beacon. Then we would have the ability to mark ambient
noise with an absolute value, thus deriving an absolute signal value
for any skimmer s/n reading.

Then it's up to program analysis of all the signals that came in
during a contest. The basic reference points become certain functions
against all the data or complete categories of data.  Everything is
very large sample analysis. It would be yet to be determined what
degree of dB accuracy could be proven.

It would be useful to operate these skimmers to a separate server just
used for the signal trio, and keep ALL the data readings, instead of
using the [necessary for general spotting use] reducing a single
skimmer's data release to a skimmer's reading of a given station on a
given frequency to once every ten or fifteen minutes.

Then it would be simple to remove fades, or measure fade depth, etc in
the data analysis math.

73, Guy.