EVM430-FR6043: No signal detected in up and downstream channel

Hi Manos,

Please post the image of your transducer/pipe setup. Is this a clamp on?

BR,
Leo

Hello and thanks for the reply.

I am trying to do a Trans-axial setup like the photos.

When the transducers are in parallel setup there is a response see the image.

I supose that trandusers are working and need calibration.

But I would like to set them up Trans-axial or v to get better results.

Hi Manos,

In order for this to work properly, you need the same material from the transducer face to be making contact via an utrasonic couplant with your tube. You can purchase transducer which have an angled face and are designed for angled clamp-ons from manufacturers like Jiakang.  You can find an appnote on clamp-ons here:

www.ti.com/.../slaa949.pdf

BR,
Leo

Hi Leonardo, I have 3d printed a case to fit in the transducer.

See the Image

I think it works, because when the transducers are set face to face there is no error.

When the tube is between the transucers I get the following image  in the ADC Capture and the error "No Signal Detected in up and downstream channel"

What is your opinion? It is a matter of microsetup until to find the best placement, or I should take in consideration something else?

Thanks in advance

Manos 

Hi Manos,

You might run a frequency sweep to see where the resonant frequency peak is for your clamp on also. The material of the 3D printed material is likely not the same as the pipe you are making contact with. If you could 3D print using a similar material - like CPCV, you would get a stronger signal. Are you at the maximum gain setting? You might also increase your ADC start capture time by 10us.

BR,
Leo

Hi Leonardo,
thanks for the help!

I have already run frequency sweep, and I have already set to the best frequency

By increasing the start capture gap by 20us, as you suggested, I have the following results

By decreasing the number of pulses to 20 I get

But the error persists.

Any suggestions to alter configuration parameters before proceeding with 3d printing.

Thanks in advance

Garefalakis

Hi Garefalakis,

Can you increase the gain further? Please post your current configuration tabs.

BR,
Leo

Thanks Leo,
these are the configurations

Thanks

Manos

Hi Manos,

You should increase your gain to get a signal with at least 300 ADC counts. You might also need to experiment with your envelope crossing threshold, you might try 13, 15, 17, 20, etc.

BR,
Leo

Hi Leo,
I just tested your suggestion, but the problem persists.

May I ask you a clarification, the red Line is the UPS and the Blue the DNS.
The plot we get are the results of what the receiver gets in each case, correct?

The signal that is transmited is like the image.

It gets a signal but the matching is not very close to the original. Correct?

It seems that the signal is transimited and has alot of noise.

Do you agree?

Before I start disassemble, cleaning and grassing the surfaces, any advice?

Thnaks in advance

Manos 

Hi Manos,

What is the diameter of your pipe? Is it made of PVC? What is the thickness of the pipe? You are getting a lot of attenuation. In your settings above, you have a gain set of 1dB - when you increase this to around 20, I would expect to see a corresponding increase in the amplitude of the signal - but it looks the same. What did you increase the gain to?

It's also important that the tube be full of water and that there be no air bubbles on the inside walls as this will also attenuate the signal. Shaking the tube vigorously and having the transducers in a horizontal plane can mitigate these other issues.

BR,
Leo