wind_sensor:meeting_minutes_apr_14_2017

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wind_sensor:meeting_minutes_apr_14_2017 [2017/04/13 03:04]
mwu [Ultrasonic Wind Sensor] 		wind_sensor:meeting_minutes_apr_14_2017 [2021/09/19 21:59]
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-=====Wind Sensor Team Meeting-April 14, 2017===== +
-**Attended: Mengyuan, Creighton, Scott** +
-=====Acoustic Wind Sensor===== +
-  * Updates: +
-  * To Do: +
-=====Ultrasonic Wind Sensor===== +
-  * Updates: +
-    * Right before the CDR, made the realization that instead of going through the trouble of offsetting the received signal and using a threshold detector, we could keep the received signal centered at 0V and use a zero-crossing detector. This will simplify our design by quite a bit (we would forego the Schmitt trigger, threshold detectors, and possibly the amplifier). Also, the zero-crossing detector is relatively simple to build. +
-    * Experiments from 4/12/17: +
-      * Tested zero-crossing detector with oscilloscope:​ +
-        * Initially tried to do it with an op-amp but we were limited by the slew rate. When we did find an op-amp with a high enough slew rate, the rise time was relatively slow (see below). +
-        * {{ :​wind_sensor:​zcd-slow-op-amp.jpg?​direct&​600 |}} +
-        * We then decided to test it with our voltage comparator set at 0V, and it gave us much better results (see below). +
-        * {{ :​wind_sensor:​zcd-comparator.jpg?​direct&​600 |}} +
-      * Delay 12.5us using nops: +
-        * Not very reliable, a better approach would be to try and modify the timer'​s prescaler and initial value to achieve a 12.5us trigger. +
-      * Receiver response when sending just 1 pulse: +
-        * Sending just a single pulse through the emitter still causes a relatively long received signal. Also, there is an audible frequency (~3kHz) coming from the emitter +
-        * {{ :​wind_sensor:​single-pulse.jpg?​direct&​600 |}} +
-      * DigitalWrite() vs. fastDigitalWrite():​ +
-        * This is probably the time between the function call and the pin change, rather than the actual rise time, which is a physical property. +
-        * digitalWrite() rise ~ 22ns +
-        * digitalWriteFast() rise ~22ns +
-      * Delay vs. Timer: +
-        * The Timer was more precise and accurate whereas the delay had some relatively large fluctuations ~8%. +
-  * TO Do:+
  • wind_sensor/meeting_minutes_apr_14_2017.txt
  • Last modified: 2021/09/19 21:59
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