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P-RAEBER
Electronic Instruments |
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Interested in the
Weather? |
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The Meteograf is a precise electronic barograph designed
for the observation and recording of climatic pressure changes, which are
important indicators of forthcoming wind and weather conditions. The
instantaneous air pressure, as shown on a conventional barometer, gives
only vague information about imminent weather changes. Only by exactly
recording the current air pressure, and the rate at which it is rising or
falling, is it possible to make reliable short-term weather predictions
and to give prompt warning of dangerous weather conditions.
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Thanks to the
intelligent use of the most modern technology (microprocessor,
surface-mounted electronics, etc.) the barograph, Meteograf is able to
combine the advantages of traditional mechanical barographs with those of
purely electronic instruments, along with its own merits of small
dimensions, low weight and high precision. Ease of operation, good
readability and the requirement to reload the recording paper roll only
once per year can be taken for granted, Attractive new functions, such as
‘Zoom’, ‘Transport’ and ‘Time Change’ (see below) can be offered for the
first time in a unit of this size and price range.
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A microprocessor controls all the
functions of the barograph, Meteograf. An analogue signal from the
internal pressure sensor is amplified in a signal processor, digitalized
and input to the microprocessor, which calculates and outputs the air
pressure. Linearity and temperature correction factors for the pressure
sensor are pre-programmed into the microprocessor, thus making the
installation of trim potentiometers unnecessary. This guarantees an
extremely high accuracy over the whole operating temperature and pressure
range, as well as optimal long-term stability. There are also no
positioning or hysteresis errors.
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To set up the barograph, Meteograf, the
current air pressure is entered using the push-buttons adjacent to the
display. If the current air pressure is not known, the local elevation is
entered instead. The barograph, Meteograf then automatically converts this
to the equivalent air pressure, as defined in the ISAO Standard
Atmosphere.
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The barograph,
Meteograf can be used at any altitude between -500 m and 6'000 m above Sea
Level (-1,600 ft to 20,000 ft.) Air pressure in the range 960 mBar to 1055
mBar (28.3 inHg to 31.2 inHg), reduced to Sea Level, will be displayed and
recorded.
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4-Day Display:
Rectilinear and Ink-free |
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The scriber point
engraves the barogram into the reverse side of the waxed paper roll. The
pressure record from the previous four days is shown clearly in the main
display window. The continuous rectilinear record (unlike that of many
other barographs, which produce a circular barogram) is therefore produced
without using felt-tip markers or pens. (There is therefore no dirtying of
the fingers or of the apparatus itself, and no requirement to replace or
replenish markers or pens.) Because the scriber is behind the paper a new
paper roll can be loaded into the apparatus as easily as a film into a
camera. One paper roll is sufficient for one year’s operation.
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The paper movement is
controlled to extremely high tolerances by a small servo motor. A second
servo motor controls, via a spindle, the movement of the scriber.
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In addition to the linear display in the main window, the barograph, Meteograf has a numerical
LCD display. This normally shows the current air pressure, but is also
used to select and adjust the barograph, Meteograf’s operating functions.
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The LCD can be used to
observe short-term pressure changes which would be indiscernible on the
main display. Together with the current air pressure, the overall change
in air pressure (+/- 0.1 mBar) in the last 1, 5, 15, 30 or 60
minutes may be displayed. This enables a uniquely accurate observation of
the approaching weather.
(Hier a change of – 0.1 hPa in 30 minutes)
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An electronic filter cancels out fluctuations in indicated
air pressure caused by operation in rough water.
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Weather conditions,
particularly wind strength, are dependent on the rate at which air
pressure changes. For any given geographical position, a given rate of
change of air pressure may be defined as indicating an imminent storm. To
provide prompt warning of this, the barograph, Meteograf has an aural and
a visual alarm, which is activated when the rate of change of atmospheric
air pressure exceeds a preset limit. This limit is adjusted by the
operator to suit the perceived danger level. (Note that, if required, the
operator can turn the aural warning off, leaving only the visual warning
active.)
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Transporting the
barograph, Meteograf usually results in a change in altitude, which in
turn produces a change in air pressure unrelated to any meteorological
effects. When in ‘Transport’ mode, the Meteograf ignores these changes and
displays the current altitude on its LCD display. When the relocation is
complete, the Meteograf can be easily reset to its normal display mode. An
overall correction to the display can then be made to account for any
weather-related pressure changes whilst the device was in ‘Transport’
mode.
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To reduce power
consumption. the microprocessor is automatically switched to an
energy-saving mode between measurements, with only the LCD display and
other basic functions operating continuously. The total power consumption
is so low that the barograph, Meteograf will run off a single household
battery for about 12 months. There is no requirement for any connection to
an external power source.
The battery voltage is continuously monitored. The LCD display indicates
battery capacity as one of four levels; Charge sufficient, Charge low,
Battery change required and Battery flat.
To ensure
maximum reliability and durability when operated at sea, or in any hostile
environment, the barograph, Meteograf uses high quality gold-plated
electrical contacts throughout. For battery connections, these are
duplicated. The electronic parts are lacquered for protection against
corrosion. The mechanical parts are manufactured from stainless steel and
all other parts are high quality plastic.
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The ‘Meteograph‘ is
also available with a PC-Interface if required.
The ‘Meteograf’ contains a memory in which the barometric pressure data
recorded over the last ten days is stored. The data is recorded to a
tolerance of 0.1 hP. (Equivalent to 0.1 mBar.)
Using the data transfer cable supplied, this data can be downloaded to a
PC for permanent storage or for further manipulation.
The software is compatible with Microsoft ‘Windows’ Versions 95, 98, NT
and 2000. Using the ‘Excel’ program, the data downloaded can be
automatically displayed graphically using a Macro function.
As this software is freely available, it can be customised by the operator
to suit his or her individual data processing requirement.
Her an example of a recording
of the last 5 days
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The barograph, Meteograf is a true European! Over 90% of
the components are made in Europe and assembly is performed exclusively in
Switzerland. |
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