New microwave motion sensor

Don M

Has anyone played with this yet? I ordered one and should receive it·shortly. My question is if I were to use this sensor in a closed fixed size area would it be able to sense movement or react·to something as small as a marble being dropped through its sensing path?

Mike Green

1) A marble may not work. Glass and plastic are generally transparent to microwaves. A marble-sided metal ball might work (or metal coated marble). There'll be a little scatter from a glass or plastic marble, but not a lot.

2) The sensor works by using the Doppler effect. That means that it reacts to motion towards or away from the sensor. If you drop a metallized ball through the field of view of the sensor, it will react the least when the ball is directly in front of the sensor and more as it falls into view or leaves the field of view since the velocity of the ball towards or away from the sensor will be at a minimum when it's directly in front.

C-Bob

Trouble with the mw sensors si wavelenght - anything smaller than lenght of wave is for mw sensors invisible. For this sensor (+- 3cm/ 1in) Tenis ball is maybe useful.

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C-Bob

Every problem·have at least one·nice, simply and·wrong solution.

Don M

Thanks for the answers.

Mike- I was referring to an object about the size of a marble, not a marble in particular but thanks for the insight into the effects of microwave with respect to glass, etc.

Once I recieve this device and do some experimenting I'll let you know how it works out.

Don

JD

Don,

When I was playing with the module, I threw a tic-tac (breath mint) on my desk from behind a metal wall where I was standin, and the sensor saw the motion. The sensativity was up all the way on the sensor and there was no other movement; but I dont forsee an issue with a marble sized object being able to be detected from a reasonable height.

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Respectfully,


Joshua Donelson
www.parallax.com

bjhamltn

Can more than one sensor be used in the same space?

JD

bjhamltn,

Testing would have to be done to confirm or deny that with 100% certainty; but I don’t see technically why not. However, the sensitivity adjustment works very well. What is it you are trying to sense?

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Respectfully,


Joshua Donelson
www.parallax.com

Brian Riley

Would be interesting if you could replace the standard pot used for sensitivity and replace it with a digital pot so sensitivity could be under software control.

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cheers ... brian riley, n1bq, underhill center, vermont
The Shoppe at Wulfden
www.wulfden.org/TheShoppe/

Wolverine69

Where can I find a picture of the antenna side of the motion sensor?

All the pictures I've been able to find of the sensor show only the potentiometer side.

JD

Wolverine69,

There is a picture in the documentation. Here is a link to the product page for your convenince; look under Downloads & Resources, there will be two links, one for the manual and the other some sample code.

X-Band Motion Detector:
http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176/CategoryID/51/List/0/Level/a/ProductID/606/Default.aspx?SortField=ProductName%2cProductName

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Respectfully,


Joshua Donelson
www.parallax.com

Wolverine69

Joshua,

Thanks for the link, I'd already seen that document and it has a drawing of the sensor, not an actual picture from a camera.

I just thought it was odd that there would be an actual picture of what I consider to be the backside of the sensor, but no picture of what I consider to be the frontside or 'business end' of it.

It's no big deal though.

JD

Wolverine69,

Gotcha, yeah the doc depicts the correct view of the front antenna, but I'll suggest an alt view to be added to help answer that question.

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Respectfully,


Joshua Donelson
www.parallax.com