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Forum Index : Microcontroller and PC projects : Problem with ultrasonic range

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WhiteWizzard
Guru

Joined: 05/04/2013
Location: United Kingdom
Posts: 2794
Posted: 05:15pm 18 Mar 2014
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Hi Greg,

Have you tried pointing the unit at a wall around 3.5 metres away (and no chairs or anything else potentially in the way). I was able to get up to 3.9 metres very consistently with my module (which is exactly the same layout as the one in Franks photo). Just that the 2.8meters you are peaking at seems a little too short of the claimed 4.5m.

I did find that if objects were in the potential 'line-of-sight' of the module then the reading became rather erratic - guess that should be expected.

The other word of warning as I previously posted is NOT to try detect/measure an object which absorbs UltraSonic.
Seems an obvious thing to say but I kept wondering how my wife kept coming into the room without her being seen by the unit. Turned out it was her 'fluffy' dressing gown absorbing all waves and a value of -1 being returned whenever she approached. Bearing in mind the unit was pointing into free space (and hence already returning -1) it gave the effect that she was undetectable!

The problem was immediately solved by removing her gown . . . . .
For everything Micromite visit micromite.org

Direct Email: whitewizzard@micromite.o
 
paceman
Guru

Joined: 07/10/2011
Location: Australia
Posts: 1328
Posted: 07:59pm 18 Mar 2014
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Who removed it?
 
vasi

Guru

Joined: 23/03/2007
Location: Romania
Posts: 1697
Posted: 11:10pm 18 Mar 2014
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Now you can sell her gown on e-bay as a cloaking unit.

https://www.youtube.com/watch?v=3V1PwpoDqzM

Or maybe not...
Hobbit name: Togo Toadfoot of Frogmorton
Elvish name: Mablung Miriel
Beyound Arduino Lang
 
Grassy
Newbie

Joined: 06/07/2014
Location: Australia
Posts: 12
Posted: 02:56pm 21 Aug 2014
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I recently bought 2 of the cheap eBay HC-SR04 ultrasonic modules hoping they would be ok with the Micromite. Unfortunately they both seem to be limited to a distance of around 70cm.
I have tested them in the open by slowly moving a large sheet of cardboard away until the distance reading didn't increase any more. One works to a maximum of around 70 cm while the other works to about 85 cm but then the readings get very unstable.
I found this thread after doing a search on the forums and have tried TassyJim's tester program as well but get exactly the same results. NB I had to increase the trigger width substantially to around 6ms as noted elsewhere to get it to work.
I can only assume as has been pointed out many times before on this forum that you get what you pay for.
As my project requires a distance measurement of at least 3 meters, can I ask if anyone can recommend a good quality sensor that is known to work up to at least this distance.

Tony
 
Bizzie
Senior Member

Joined: 06/07/2014
Location: Australia
Posts: 185
Posted: 03:19pm 21 Aug 2014
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I bought similar units from Ebay. They work fine to 2.5m I have not tested them beyond that as my application only required less than 1m.

3m is the limit of these sensors from what I have read.

These sensors look good but much more expensive - Distance sensor

Rob White
 
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