Hard to understand. It should be expected, that the circuit generating the Tx signal can also control the switch?however the drawback of using this circuit is that i have to manually do the switching using a microcontroller
vsmGuy said:Hi miskol,
I really don't think what you term as "noise" is really that - infact, its due to considerably less loading of the transducer.
I assume you had the sensor setup in a reflective setup with an obstacle very close to the transducer - maybe 1 - 2 cms away (varies on temperature).
I agree with Arthur. [after-]ringing (aka ringdown) should be considered. Here's an example of what ringdown may look like: http://www.prolifictec.com/filehost/Ringdown_waveforms_rev01.pdf. I've recorded these waveforms. I wonder what do you think about them.arthur0 said:For instance, I can say that the [after-]ringing is the limiting factor of how short a distance I can measure...
I've built an tested all components for that project, but didn't integrate them. That project was shelved. I've been overwhelmed with a high-maintenance girlfriend and fast-revenue work for a good portion of this period. She's no longer around. I'm planning a quasi-sabbatical. Maybe I'll pick this project up again.vsmGuy said:@kender : I am sorry if this does not ring a bell, but did you happen to mail me something back in say 2007 or so about making simlar sonars? If I indeed recalled correctly, then what happened to the project? Did it work out?
miskol said:CH1 is amplified so that the transmitted pulse sent to the transmitter have stronger pulse. it's like giving volume boost.
miskol said:The ringing problem that u all have discussed above, can be reproduced when the cable from the transmitter and the receiver is crossed with each other, or twisted together. so to avoid this problem, i've used coaxial cable.
Which is why i suspected that the internal layout of the switching IC, the inputs for both Tx and Rx is very near each other that have make the "noise" i mentioned earlier.
On the 1st order, the ratio of ringdown power to TX and reflection (RX) power should remain constant with respect to TX power. However, boosting the TX will increase the SNR of the reflection (RX). That's a good thing.vsmGuy said:Boosing the excitation signal makes matter worse by making the transducer ring, reducing the effective min. distance.
I was building building a sonar for water. Something similar to a business end of a fish finder, but more flexible and with a capability to array a bunch of them.vsmGuy said:I believe Kender and I would take this project up as well?
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