How the motion sensor light affect to ultrasonic sensor distance

Comments

• Franklin Posts: 4,747

  2010-04-09 22:09 edited 2010-04-09 22:09

  There should be no correlation between the two. Could you give the model numbers of the devices and what you are getting when used seperatly and together?
  
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  - Stephen
• An Nguyen Posts: 10

  2010-04-16 16:26 edited 2010-04-16 16:26

  There are two motion senors on the ceiling at two opposit corners in the LAB room. Their name are DT-205 Watt Stopper(Dual Technology ceiling sensor). These sensor combine PIR and Ultrasonic ( 40 Khz) into one unit.
  
  When I use the Ultrasonic distance sensor to detect object in this room, it not work properly. The number appear on the Parallax LCD screen is not stable. It doesn't detect object greater than 5 inches far from the sensor.
  
  I have built two ultrasonic distance sensors. I put them opposite side ( face to face), then put one square ft cardboard between them. Both of them work very well at the hall way of the LAB room. They doesn't interfere each other.
  
  How ·the DT-205 sensor affect to the ultrasonic distance sensor?
  
  Thank you for your time.
  
  An Nguyen
• hover1 Posts: 1,929

  2010-04-16 19:42 edited 2010-04-16 19:42

  @AN Nguyen
  
  It seems the DT-205 sensors are flooding the room with their transmitted ultrasonic signals which are confusing the Distance Sensor. Your distance sensor relies on putting out at pulse and then listen for the echo. If another transmitter is putting out a pulse at the same time it will give you incorrect results.
  
  Jim
• An Nguyen Posts: 10

  2010-04-17 02:28 edited 2010-04-17 02:28

  I still don't understand why two ultrasonic distance sensors do not interfere each other when they·work close together, but DT-205 confuses ultrasonic distance sensor?
  
  Thank you very much.
  
  An
• Franklin Posts: 4,747

  2010-04-17 04:08 edited 2010-04-17 04:08

  An said...
  I still don't understand why two ultrasonic distance sensors do not interfere each other when they·work close together, but DT-205 confuses ultrasonic distance sensor

  That's just how things are sometimes. If you want to spend the time you could build an ultrasonic translator so you could capture the waveforms of the different sensors and see if you could figure it out.
  
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  - Stephen
• Sandhuamarinder Posts: 85

  2010-04-17 06:29 edited 2010-04-17 06:29

  Ultra sonic sensors sends the sound wave which is total different thing but it only gets affected by the air humidity and by wind. Bcoz Ultra sonic are the waves on which dog talk and elephant talks these are the much higher frequencies which we cant hear and they work upto real far distances elephants can have communication upto 300 km. If you had notice that if u visel at the front of dog he gets crazy bcoz they gets distrubed by that and really irritates them bcoz they talk on higher frequencies then us. And when we visel we create higher frequencies.
  
  In ultra sonic sensors what happens is that its sends the waves and the reciever waits for the waves to hit it back. So far the sensor more are the chances are the waves will be not accurate by they are just very very accurate bcoz they are built according to that. But they only get little bit changed if there is humidity in the air. Or something.
  Or other devices working like that which is intrupt them.
  
  According what i had learnt till now light may affect the ultra sonic sensor according to me but its impossible that u will not get readings. Bcoz light will affect with there small tiny dust particles which fly in air will come at the front of the wave and which may act as a dust and absorbs the sound wave but its not possible that all of the wave will get absorbed.
  
  Rest all depends upon at which kind of surface u are hitting the waves. Is it diverted to some other angle which does not make 90 to it. So the waves doesnt come back.
  
  And if u try to notice ultra sonics sensor also make click kind of sound when they gets the reading.
  
  I am just student. I maybe wrong