Thanks Theo (ilioSS)

I changed the connection like you did.

Make sure that the two drive lines are not earthed, the drive is differential and
if one side is earthed you only get one half the driving signal.

How can we check if a set of sensors are best for each other?

Try different pairs until you get the closest received amplitudes.

I will take a scope to check the CRO signal. ( can send scope pictures)

That would be very helpfull.

You only need low resolution photos, these would be really usefull:
(Make sure you have the voltage levels in the photos)

Output from 1st stage with example program CRO.
Output from 2nd stage of the amplifier with example program CRO.
Output from the LPF with example program CRO.
Output from the envelop detector with example program CRO.
Output from the zero crossing detector with example program CRO.

Cheers.

Hi ilioSS

Sensors should be fine.

Do you have a cro, the program "calibrateCRO" can be used to see if you get the same waveforms as me.

Are you using "calibrateENVELOPE" to get the 8000 you should be able to adjust the 10k pot to get
4000. 

You must get this value and 3000 for the ZCD for the system to work.

The 918 is just a small signal diode, any one should work.

I cant tell you what is the problem, but you must go back to the absolute basics.
Program the arduino to send 40khz pulses and check the result.
I'm afraid that a cro would be very usefull.

cheers

rkguy

ravensburg was on the web when I started my project.
They like to keep the signal processing a secret so I could not use any of their information.

Interesting to see they now have a reflecting suface which many commercial models have.

I have experimented with a reflector layout but was unable to get a big enough signal.

I have just become aware of the hackerfleet design.

I have only had a quick look but I could not find their signal processing.
Their circuit information looks good.

As I have said before my design could be much improved.
I do not know of any new designs and the eagle files are still current.

cheers

but you still don't know which of the 25 cycles is which by the time they reach the receiver.

This is the the crux of the problem, we cannot know for certain.

We get an approximation using Thresholding:
This is the simplest method and I incorporate it in this design. The tof is measured when the
amplitude of the received pulse exceeds a fixed amplitude.
In theory the error of this measurement can approach zero if you average an infinite number of
samples.
I average over 3 seconds.

We then have a tof with an error, we get a closer result using the phase shift.

You cannot use the phase shift alone as it repeats itself every wavelength(25 micro sec).

Hope that this helps.

FireFury

Yes you are exactly correct.
If you increase the number of pulses sent the received signal gets much easier to read.

After 16 pulses we get diminishing returns.

In the program I send the 40khz pulses for 64ms - about 25 pulses.
This gives a good tradeoff between readability and total time for the measurement.

cheers

If have an android phone spare so I thought I might use it for my weather station.

http://arduino.cc/forum/index.php/topic,8874.0.html

Much better than old 7 segment displays.

ArduinoCommander is a great application, I went through all the information and was really
impressed with the displays available.

Unfortunately my phone uses version 2.1 and ArduinoCommander sets version 2.2  as the  minimun.
So its not available on the  google Market for me and anyone else with 2.1 or lower.

I sent them an email to ask if it was possible to change to 2.1
It maybe there are some API's they need from 2.2 and  its not possible.

Anyone else with the same problem?

yes, at this time I would recommend mchr3k version.

Download UltrasonicAnemometer.zip from:

http://code.google.com/p/mysudoku/downloads/list

To answer your question I need a lot more information.

Is the analog voltage a log range or the digital display?

I can only repeat a previous answer:

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.

rolandoag


I connect the cable like this:

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

There is no ground connection at the transducer.



I use 8 volts for the analog amplifier circuit to give full digital output of 5 volts from the opamps.

jose156

(analog)H2, H5, H7 and (digital)H10 are earth and are all connected.

(analog)H1 is the amplifier input and is connected to the (digital)4052 pin 3 designated as "amplifier".

(digital)H1 and H2 go to north transducer.
345678 go to the others.

(analog)H3 goes to the (digital)328 pin 5 designated as "envelope".
(analog)H6 goes to the (digital)328 pin 4 designated as "ZCD".
(analog)H8 goes to the (digital)328 pin 28 designated as "temp".


H11 is a test point and goes nowhere.

I have posted the eagle files I could find for my projects:

Download eagle_files.zip from:

http://code.google.com/p/arduino-projects-carl47/downloads/list



I use:


Easily Applicable Graphical Layout Editor(EAGLE)

Version 5.6.1 for Windows

Light Edition

Copyright (c) 1988-2009 CadSoft
All rights reserved worldwide

Add the Sparkfun  Eagle parts library     "SparkFun.lbr"
Instructions from sparkfun tutorial "Beginning Embedded Electronics - 8"




The schematics relate to the following projects:

Weather Station:

http://arduino.cc/forum/index.php/topic,8874.0.html

4digit1 ,  indoor , outdoor , supply


Programming the 328:

http://arduino.cc/forum/index.php/topic,59968.0.html

328_program


SRAM memory:

http://arduino.cc/forum/index.php/topic,50006.0.html

SRAM2


RF Links:

http://arduino.cc/forum/index.php/topic,60239.0.html

rf_link_tx , rf_link_rx


Ultrasonic Anemometer:

http://arduino.cc/forum/index.php/topic,53569.0.html

analog , digital , ultra_amp

Thanks Mike,

I do have the eagle schematics and can post them but I hesitate because I,m
currently doing a complete circuit redesign.

The new circuit will be much improved and smaller.

Cant give you a timeline.

Let me know if you want the old files.

on a bread board the parts cost me about AUD $60


I will not answer any more questions until 1-11-2012

I will be on holidays, including catching a train from KL to bangkok and I will not check my sites or mail.

neat, I can see the picture from the second link but the first link:

http://www.doctormonk.com/2012/08/review-4-digit-7-segment-led-and-rtc.html

gives me:

Internet Explorer cannot display the webpage

It may just be my setup but maybe you could check the link.