As shown in the figure below, I used the TDC1000-C2000EVM for sound speed measurements, and in yellow I connected the TX1/RX2 signals directly to the oscilloscope. The other is the blue one is the COMPIN signal. The latter signal I am not sure if it is an echo signal. Because these signals are constantly moving without me changing the distance the ultrasound travels. The signal in the picture is a transient signal that I intercepted.
1. In the figure below, the waveform marked in red seems to be an echo signal, but the signal is constantly moving with time. I conducted the experiment underwater, and the measurement distance was about 10cm.
2. The resonant frequency of the sensor is about 1M.
3. The configuration of the upper computer is shown in the figure.
4. I have adjusted the upper computer configuration and various settings numerous times now, but still no results. I am not sure if there is something wrong with the evaluation board. Or is there something wrong with my configuration.
5.Another point I would like to clarify is that I have consulted many similar problems before, but each time the engineer also gave a few exchanges and did not effect the method to end the question. So I have to re-explain every time I ask a question again. Is there a more direct way of communication, which will help me to debug successfully as soon as possible.
Hello Lei,
Thank you for the information.
At about 10cm it should be the about the third waverform that you are seeing in your COMPIN pin. ToF = (2* 10cm)/(1480 m/s) yields a time of flight of about 135us.
I performed a similar test with a 1MHz transducer with 10cm of water. Unfortunately I could not use a metal wall since I do not have a tank to accommodate for this and I mounted my transducer at the outside bottom of the tank, since I do not have a transducer rated for operation inside the water. My settings and setup can be seen below this yielded a ToF result of 136us:
Here is a scope capture of this setup:
As you can see I am also obtaining some noise possibly the transducer still ringing at the beginning of my measurement but it was not enough to trigger the signal. I noticed that on your setup you have FORCE_SHORT_TOF enabled, this will cause the device to begin detection quickly after the burst is complete. You want to avoid this because the device will then trigger on the transducers ringing. This is why its imperative to calculate the timing needed for your signal and calibrate your system to listening window at the appropriate time.
If I want to avoid listening to objects early on I can shift my listening window to begin at a later time. I can do this by changing the values of TIMING_REG in the following instance I changed the value from my previous 0us to 40us, this was done by increasing the value of TIMING_REG[7:0] to a value of 70. It yielded the following results:
As seen, the COMPIN will not get enabled until the listening window is active ignoring the noise or false echoes. As far as why you are getting incorrect echoes, please ensure the frequency of the transducer is correct, ensure that the device is actually transmitting the pulses, also verify that the device is rated to be used inside the water tank, you can also test a different 1MHz transducer. The configurations on my board are the same as the out of the box configurations.
Make sure that the values are being written to the device properly, in some instances when updating the values the GUI was not writing them so when a value is written click the read button to ensure that it was written to the device.
Sorry to make you repeat some questions we try to keep every thread to 1 question so that it is easier for other people to follow. To answer your last question, the best method of contact is through the forum, you are free to send me a friend request through the forum in order to send private messages.
Best,
Isaac
