|
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.
Illustration 3. basis that was
set ratio resistors and R2. received signal
has 0,2 peak peak image above curve with green colour. received 0,5 peak peak,
output signal would 2,85 V. VAMPL amplitude generating wave and was changing simulate different
conditions depending environment and whether within usage.
The pink line comparator reference one.3.
The amplified output operational amplifier connected positive input of
the comparator LM339 STMicroelectronics. Its positive peak reach 2,2 V. reach this by
connection positive input through resistor 1,65 branch.
The output operational amplifier cyan blue curve. This requirements comply dual amplifier TS912
by STMicroelectronics [16]. Such operational amplifier has rail rail one
with desired voltage specification.
16
. when output amplifier reach 2,08 set
on reference, output comparator coloured yellow will positive voltage level. First adjustment by
adding component blue one curve. This signal connected positive input of
operational amplifier.3 Amplification received signal and comparator
For amplification received signal was aim use operational amplifier which permit
us supply 3,3 and ground. keep component
hear capacitor takes places. Another solution could connect receiver directly to
positive input and 1,65 branch. require add input
signal component 1,65 shift into working range. Values and feedback resistor ensure
multiple 5,7 input signal the output. Unfortunately this one doesn’t include Pspice component
library.
As was said amplifier has unsymmetrical power supply. widely using comparator which
works with 3,3 logic and therefore the output this comparator can connected
directly the digital input port evaluation board.4: Schematic receiving amplifier with comparator
For the first simulation was set 0,1 amplitude VSIN source. Another rail rail low voltage amplifier which can found there TLV2262
by and was chosen for simulation. Course negative input can seen orange coloured curve.
For simulation received harmonic signal ultrasonic sensor VSIN source was
used.
Common voltage level during testing was 0,5 peak peak
