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Kategorie: Diplomové, bakalářské práce |
Tento dokument chci!
Práce popisuje principy a problémy při realizaci ultrazvukového anemometru. Je popsán princip výpočtu rychlosti větru a následné korekce výpočtu. Pro realizaci jsou využity ultrazvukové sensory a microcontrolér ARM Cortex-M3. Práce se zabývá generováním PWM signálu, jeho analogovou filtrací, zesílením a odvysíláním. Na přijímací straně jeto nízkonapěťový zesilovač a komparátor. Vyvíjený kód je popsán pomocí vývojového diagramu.
1)
where d[m] distance and c[m/s] airspeed.1) have add variable which represent speed wind v[m/s]. Distance between sensors a
constant, but airspeed should corrected concrete atmospheric conditions [1]. know the air temperature T[°C]
between sensors, can correct airspeed according following equation [1]:
(2. The wind affects the sound wave making going slower faster. [1]
1.1 Correction speed
Airspeed dependent mainly temperature.4)
When the vector wind speed has opposite direction than propagation the
sound, there will increase time delay. can expect time delay non windy conditions based this
equation:
(2. case less time
delay obvious that airspeed increased speed wind.3)
where a[g/m3
] amount water the air. Then have correct our measured temperature
and use the corrected temperature calculation above (2.2)
There another weak dependence air humidity.2 Time delay windy conditions and wind speed
A sound wave affected the movement the transmission medium, air the
wind. equation
(2. With air temperature 20°C the
measured temperature with 100% relative dampness about higher.2). can adjust this equation just calculate
2
. When vector wind
speed same oriented like direction sound propagation, obtain the equation [1]:
(2.
1. The correction based on
knowledge amount H2O grams per cubic meter. this case can suppose that the wind
speed the equation (2. [1]
(2.THEORETICAL BACKGROUND
How was said, the calculation wind speed proceed knowledge time delay
between sensors. The increase water molecule in
the air cause increase airspeed.4) negative
