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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 Correction speed
Airspeed dependent mainly temperature. equation
(2. The wind affects the sound wave making going slower faster. this case can suppose that the wind
speed the equation (2. [1]
1. can adjust this equation just calculate
2
. Distance between sensors a
constant, but airspeed should corrected concrete atmospheric conditions [1]. 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.2 Time delay windy conditions and wind speed
A sound wave affected the movement the transmission medium, air the
wind.4)
When the vector wind speed has opposite direction than propagation the
sound, there will increase time delay. Then have correct our measured temperature
and use the corrected temperature calculation above (2.
1.1)
where d[m] distance and c[m/s] airspeed.2)
There another weak dependence air humidity.1) have add variable which represent speed wind v[m/s]. The correction based on
knowledge amount H2O grams per cubic meter. The increase water molecule in
the air cause increase airspeed. know the air temperature T[°C]
between sensors, can correct airspeed according following equation [1]:
(2. With air temperature 20°C the
measured temperature with 100% relative dampness about higher. [1]
(2.THEORETICAL BACKGROUND
How was said, the calculation wind speed proceed knowledge time delay
between sensors.2).4) negative. When vector wind
speed same oriented like direction sound propagation, obtain the equation [1]:
(2
