Go Down

Topic: Ultrasonic Anemometer (Read 32 times) previous topic - next topic

tom125

Quote
What exactly gives you these values? Is it the Arduino IDE ?


yes ? use arduino 1.0 program. But when ? download calibrate temperature program to the arduino uno with using arduino 1.0, it gave me -10 ,-9.87,-10... values from serial monitor but ambient temperature is 23 C.

Quote
Please provide exact details on what you have connected.


? convert your connection in a useful way for my ardunio because your connection is according to the atmega 328. For example, in  your circuit you connect temperature connecion to the 28. pin ( PC5 (ADC/SCL) ) ? connet it in my circuit to the analog input 5 pin. Another example you connect zcd conection 4. pin (PD2 (INT0) ) i connect it in my circuit to the digital pin 2.

tom125


Actually i couldnt understand what you said about transducer pins, you mean that i shouldnt connect short pin anywhere and i should just connect  long pin to one of my third connections cable and shielded connections at earth  so i have one more connections what about it?
Thank you very much for your fast replies

carl47

#17
Jun 04, 2012, 06:30 am Last Edit: Jun 04, 2012, 06:34 am by carl47 Reason: 1
OK I can see what you are doing:


TRANSDUCERS ---- arduino uno ---- Arduino IDE display


Does the calibrate resisitor 1k make any difference. The voltage at analog 5 should change.

If it does not you have a analog circuit error.

If it does and the display "external temperature  =  10.0" does not change you have a program error.

Your job is to find and fix the problem.


The cable:

H1.......................................................long pin
H2.......................................................short pin  NORTH transducer
Earth------------------------------

..........wire 1
..........wire 2  twin shielded microphone cable
----------shield




outleo

#18
Jul 25, 2012, 03:37 pm Last Edit: Jul 25, 2012, 03:39 pm by outleo Reason: 1
Good job Carl, nice anemometer. Im trying do create my own, my phase shift works well, but my TOF values changes a lot in some wind ocasions. I used the circuit of this article: http://www.ozitronics.com/docs/k168.pdf ....
What happens is that sometimes the transistor saturates on one period after or before the actual period, that is the correct one. This occurs because of the variation of the amplitude of the receiving signal that changes with the wind. The transducers dont have the same properties, that means that a  8m/s wind on one pair works well, and a 8m/s on the other one doesnt. I was thinking on making two different amplifiers that uses different gains, but in some wind ocasion the same problem will happen.
Do this happens with your TOF detection circuit and you get a lot of measures to compensate that? Or is it more robust? Do you have any ideas to help?? Thank you.

carl47

A previous question asked:
Quote
Then you mentioned the other problem about transducers behavior and define Northerror[20] .
Why 20 values? An again the logic , even is there, not sure to follow why.

This relates to your problem of the differences.

From the project report we compensate using software:

We do run into another problem. Ultrasonic transducers are not symmetric for transmission and
reception. The devices are not linear components and even worse the symmetry changes with
temperature.
You can match them as north-south, east-west pairs. It's properly a good idea to do so.
However we do need to have a constant which is used to match the pairs as closely as possible.
This constant will need to change with time as the temperature changes.
I use:
int Northerror[20]; //The tof error for north-south transmit
We keep a running sample of the differences when the difference should be zero.

Go Up