ECOWITT HP3501, Руководство по эксплуатации

Страница: 40 / 87

40
the correct airport from your search results and click on it. For example,
search for “Mountain View” and click on “Moffet Field.”
6. From the resulting page find the ICAO code, if listed. Otherwise use the
IATA code. For the example above, you would find IATA code
“NUQ.”
7. Now go to a web site like AVIATION WEATHER CENTER (for US
locations) at https://www.aviationweather.gov/metar?gis=off and enter
the code you found in step 2, and click “Decoded” (to make the next
step easier) before requesting the METAR information. For the
example we would enter “KNUQ” and find a result output like: “30.09
inches Hg (1019.0 mb) [Sea level pressure: 1019.1 mb]”
8. Go to the calibration settings page and observe the “REL Barometer
value (this is the value we just adjusted in step 4 above). Compare the
REL value with the value from the airport. IN our example, the REL
display was 1022.9 where we expected 1019.1. This then tells us that
our displayed REL pressure is 1022.9 – 1019.1 = 3.8 hPa different from
the reference source.
9. Since we assumed the absolute pressure measured was correct, and we
presumably calculated the elevation related offset correctly, we must
conclude that the absolute pressure was not correct after all. It appears
to be 3.8 too high, so we’ll now enter a correction of -3.8 in the settings
for “ABS Barometer” until it reads a value 3.8 hPa lower than before.
This kind of correction is entirely normal as during manufacturing
small shifts in the pressure sensor readings can be introduced.
10. For a more precise procedure, locate a very precise barometer that you
can place right next to the console, you would adjust “ABS Barometer”
until the ABS pressure reads identical. You would then still adjust
“REL barometer” until it displays the value from the reference airport.
This procedure would also produce the correct relative pressure, but
due to a precise calibration of the absolute pressure, it too is correct.
The first procedure above generally works quite well, but for stations at
fairly high altitudes (e.g. 5,000 ft. or higher) it may be more incorrect than at