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Terminology

YAW motion from http://www.lerc.nasa.gov/WWW/K-12/airplane/yaw.html

Pitch motion from http://www.lerc.nasa.gov/WWW/K-12/airplane/pitch.html

Roll motion from http://www.lerc.nasa.gov/WWW/K-12/airplane/roll.html
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Using air pressure measurement as an indication of altitude
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from http://www.intersema.ch/site/technical/files/an501.pdf



Use of the Intersema Sensoric MS5534 digital air pressure sensor as an altimeter

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from http://www.freescale.com/files/sensors/doc/data_sheet/MPX4115A.pdf



Thanks to Josh Levine for bringing this barometer module to our attention.
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Honeywell SDX15D4 for absolute pressure
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Use an absolute air pressure (barometric) sensor to determine:
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Honeywell 163PC01D36 for differential pressure
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A differential pressure sensor is used:
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Intersema MS5534B barometer module
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from http://www.intersema.ch/site/technical/files/ms5534b.pdf





Our experience: we ordered four units in August 2007, and they were delivered within a day. The UK representative, Nick Belson Design Limited, even added a small PCB (shown above) for good measure. Very impressive!
Thanks to Josh Levine for bringing this barometer module to our attention.
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VTI SCP 1000 absolute pressure sensor
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from http://www.vti.fi/midcom-serveattachmentguid-ee324736da76ce990658c6747c5e761d/scp1000-d01_-d11_pressure_sensor_datasheet_13-03-2007.pdf

Thanks to Josh Levine for bringing this absolute pressure sensor module to our attention.
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Above image and text below from http://www.r-p-r.co.uk/windsonic/windsonic.htm
WindSonic - Ultrasonic Wind
Sensor Specification |
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| PHYSICAL |
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Size: 142mm diameter x 160mm Weight:
0.5kg Mounting: Pipe mounting 1.75 inches (44.45mm) diameter Material
External: Acrylate Styrene Acrylonitrile, Polycarbonate blend. |
| PERFORMANCE |
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Wind speed range: 0.1m/s to 60m/s Wind speed
accuracy: +/- 2% Wind direction range: 0 - 360° (no dead band) Wind
direction accuracy: +/- 3° |
WindSonic - How it works
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The WindSonic sensor uses the time of flight method of air
velocity measurement. There are four ultrasonic transducers arranged as two
pairs at right angles to each other. Each pair is used to measurer the component
of the wind in the direction between the transducers. For example if one pair is
on a North South line and the other pair is on an East West line then the North
South component VN and the East West component VE are
measured. These are then combined to give the actual wind speed and direction.
Wind angle A = arctan ( VE / VN )
Wind speed S = sqrt ( VE 2 +
VN 2 )
To look at how the component measurements are done we will take
the example of the North South transducer pair. A pulse of ultrasonic sound is
transmitted by the North transducer and the time T1 it takes to
travel to the South transducer is accurately measured. The time T2 is
then measured for an ultrasonic pulse to travel in the opposite direction from
the South transducer to the North transducer. These times are affected by the
wind blowing along the line between the transducers. For example if there is
some wind blowing from a Northerly direction, then the time taken for the
ultrasonic pulse to travel from N to S will be shorter than from S to N.
The time for the pulse to travel from N to S is given by:
T1 = L / ( C + VN )
and the time for the pulse to travel from S to N is given by:
T2 = L / ( C - VN )
where L is the distance between the transducers and C the speed of
sound.
From this the northerly component of the wind can be found
from
VN = L ( 1/T1 - 1/T2 ) / 2
and the speed of sound from
C = L ( 1/T1 + 1/T2 ) / 2
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© Barnard Microsystems Limited 2006 - 2008
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