Is there a difference in polarity for sonar sensors?

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    Polarity Sensors
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Discussion Overview

The discussion revolves around the use of sonar range-finding sensors in a robot project, specifically addressing the question of polarity and its relevance to the operation of the sensors. Participants explore the nature of the sensors, their intended use, and the implications of polarity in their setup.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether polarity matters for sonar sensors, noting the absence of clear positive or negative indicators on the schematics provided.
  • Another participant asserts that the schematics are for ultrasonic motion sensors rather than true sonar sensors, suggesting that they are not capable of measuring distance but rather detecting motion.
  • A different participant agrees with the previous point, indicating that the term "sonar" may be misapplied in this context.
  • One participant explains that the operation involves modulating a signal and measuring the time it takes for an echo to return, which is a fundamental principle of sonar range-finding.
  • A later reply requests clarification on which specific poles or points the original poster is referring to, indicating a need for more precise information to address the question effectively.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the sensors in question, with some asserting they are motion sensors rather than sonar devices, while others maintain that they can function as sonar range-finders. The discussion remains unresolved regarding the implications of polarity.

Contextual Notes

The discussion highlights potential confusion regarding the terminology used for the sensors and the specific functionalities they provide. There are also unresolved questions about the specific points of polarity being referenced by the original poster.

Megasundato
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Hello, for my robot project, I'm using a system of of sonar range finding sensors which are generally used for this type of thing. My question is of there polarity. I'm assuming that it does not matter, for there are no clear indicators of positive or negative values on any of the poles.
here are the schematics I'm following.

http://www.reconnsworld.com/ultrasonic_xmtr.jpg

http://www.reconnsworld.com/ultrasonic_rcvr.jpg

I don't know if this helps explain what I mean. I just need to know if there is any difference on any of the points.

Thanks
 
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Those schematics are not for sonar, they are for an ultrasonic motion sensor. (Admittedly they might be advertised with the word "sonar" but its just to increase sales). All those schematics can do is sense motion, they can't tell you how far away anything is. Typically the output of the receiver stage is watched for changes (simplest way is to send it through a phase or amplitude detector), because any change indicates there was motion. Polarity shouldn't be an issue unless there is some really fancy signal processing after that receiver front-end, which is unlikely for those circuits (that is, if you wanted to do something fancier than simple motion detection you wouldn't use that sort of transmitter and receiver).
 
Yeah, I thought sonar is a bit too big of a word for them lol. thanks for the help. that answers my question.
 
You should be able to use those two devices together. You modulate a signal; when the signal hits something it should echo back. Then you should be able to match the return signal. The time it takes to get your response should tell you how far away an object lies.
 
Megasundato said:
Hello, for my robot project, I'm using a system of of sonar range finding sensors which are generally used for this type of thing. My question is of there polarity. I'm assuming that it does not matter, for there are no clear indicators of positive or negative values on any of the poles.
here are the schematics I'm following.

http://www.reconnsworld.com/ultrasonic_xmtr.jpg

http://www.reconnsworld.com/ultrasonic_rcvr.jpg

I don't know if this helps explain what I mean. I just need to know if there is any difference on any of the points.

Thanks

The links show a 40 kHZ transmitter and a 40 kHZ receiver for a sonar rangefinder system. The timer and control circuits are not shown. The transmitter emits a short pulse and when the echo is received it trips the comparator in the receiver. The control circuits measure the round-trip time between transmit time and receive time and then calculate the range. This is exactly how a sonar rangefinder works.

Can you please be specific: What poles are you referring to? What points are you asking about differences?
 

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