ULTRA SONIC HOW MUCH ERROR

[mangood]

HI

i try to use ultra sonic sensor to measure distance

what  and when the worst caser maximum error that may be happen???? and on which depend >>???

any information !!!!

best regards

[GerdW]

Hi mangood,

1) read the manual of the sensor.

2) Read the manual of your DAQ device.

3) Combine the given error ratios by error propagation rules.

When you don't know how to apply point 3 you should read some basic books on "Measurement theory" - or consult Wikipedia...

[johnsold]

The worst case error will occur when you operate the ultrasonic sensor in vacuum, because you will not receive any signal at all.

Lynn

[mangood]

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@GerdW wrote:

Hi mangood,

1) read the manual of the sensor.

2) Read the manual of your DAQ device.

3) Combine the given error ratios by error propagation rules.

When you don't know how to apply point 3 you should read some basic books on "Measurement theory" - or consult Wikipedia...

---

thank you,i know these ponits

but you know some time practicatl result diffrent in some how from data sheat

so maybe some one work on it and see some error and i need how much  happen

best regards

[mangood]

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@johnsold wrote:

The worst case error will occur when you operate the ultrasonic sensor in vacuum, because you will not receive any signal at all.

Lynn

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dear 

i mean if the sensor say that 14 cm is the distance  but the acutal diatance is 16 so the error is 2 cm

this is what i mean for the error

[GerdW]

Hi mangood,

what should we look at? You neither tell the type/producer of the sensor nor do you tell the type/producer of your DAQ device. We don't know anything about your measurement setup!

So points 1 to 3 of my first answer still hold true: look at the manuals of your hardware...

[mangood]

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@GerdW wrote:

Hi mangood,

what should we look at? You neither tell the type/producer of the sensor nor do you tell the type/producer of your DAQ device. We don't know anything about your measurement setup!

So points 1 to 3 of my first answer still hold true: look at the manuals of your hardware...

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Devantech SRF04 / SRF05 Ultrasonic Range Finder 

one of them i will use

[johnsold]

mangood,

In addition to the information GerdW pointed out that only you have, you may also need to know the temperature, humidity, and atmospheric pressure along the path between the sensor and the target.

Lynn

[mangood]

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@johnsold wrote:

mangood,

In addition to the information GerdW pointed out that only you have, you may also need to know the temperature, humidity, and atmospheric pressure along the path between the sensor and the target.

Lynn

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dear 

I will try it in my room so these measurement is hard to measure

did any one have approximation value ???

I mean from his experience

regards

[johnsold · Accepted solution]

mangood,

You can use standard values from handbooks.  Any errors in your room will be much smaller than the one part in eight you mentioned in one of your earlier posts.

Ultrasonic distance measurements are based on the time it takes the sound to travel between two points so anything which affects the speed of sound in the air can change the result.  According to a table on Wikipedia the speed of sound increases about 1% for a temperature change from 20 to 25 degrees C.

Lynn