Advice on my self-learning sonar circuit

Have you read the articles about sound waves, I would like to know how much knowledge you have, what kind of experience you have. Unfortunately, there are not many people left who have time to solve this problem with an understanding that increases as information is shared. ( radar and sonar rf waves ) I would like to teach you more than explanatory resources on these subjects and level up in your project. I don't know if you are a student
Normally I solve this problem with scope assisted real circuits which is my field.
Although I do different projects and develop software (it has a lifelong learning philosophy)

As far as I have read, you do not have an automatic gain circuit and you can send two types of signals on the speed of the sound wave in the water and similar issues. I will explain the calculations on short pulse meters and then I will explain the calculations in terms of continuous sound emission and instantaneous reading, the circuit here emits sound continuously, which converter do you use, piezo or mechanical converter?
I'll try to share some circuits with a cheap road circuit, be patient, it will take some time

Hello @nzmxp , my background is not electronic and I am not a student. I am a self employee, self learning enthousiast and stubborn from time to time (like with this sonar). I am aquatic biologist and some part of this field required good skill with sensors and monitoring systems. For the last 10 years I build up my knowledge at integrating sensors for my uses at diagnosing lake health status.
At the moment I am playing with an underwater drone to map water quality (temp, Conductivity, chlorophyll, etc.) and I wanted to add a sonar + obstacle detection system to it. These thing already exist but they are very expensive. I build my own and learn will doing it.

I would like to bring this sonar setup to a multi ping setup that trigger in sequence piezos oriented toward the bottom to get depth, the front and side of my drone to get obstacles. Not for resale but for my use at monitoring and sake of doing it.

My circuit above is far from optimal but after a lot of time in front of my scope I have a better understanding of how it work. The circuit can trigger a 200khz sounder and I hope I will be able to adapt it to produce other frequency 40 khz (for shorter distances) or get sediment tickness (400 khz or more) and match other piezo if needed.

I read about dynamic amplifier (not sure if this is related to automatic gain circuit). Low gain to remove the trigger and ringing from the signal and gradually higher gain to catch the echo. I understand the idea but did not find or test circuits. The IC I use now have a on/off switch. I plan to stop the IC during trigger and ringing. I see this as a straigthforward filterout setup.

I am not certain I know what converter I use. It is the sonar from a fishfinder that I better described here a year ago (stubburn me...) and made of PZT-4: https://forum.arduino.cc/t/interfacing-fish-finder-take-2/679629/58

I will be happy to have more help. I certainly need it.

thank you

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Once you understand the logic of the system, I am sure you will practice a lot.
to provide you with the conditions you want, rather than being cheap or expensive. After all, you're not going to build a side-scan 360-degree military sonar, and the cost obsession can happen to anyone.

I think you're going to measure distance. I will draw, I will be busy on the weekend

I think fish finder devices make this heat, but you like to work yourself.

(The IC I'm currently using has an on/off switch.)

What is the IC number for driving a piezo transducer?
such an IC.mi opa454 or opa547 or other

without switch .Enable → Disable 6 µs
From here you can turn the sound pulse on and off.

I use this IC with a 20 MHz GBP : OPA4322S and 30-40 close-loop gain for my 200 khz piezo. The IC is at page 6, right side IC in this TI datasheet.
Figure 26 and 27 page 15 show a delay < 2 uS when switching on and off the enable pin.

I think it can be used as both a receiver and transmitter buffer. OPA2322S key control counterparts are suitable.

I will share the (STC) and (FTC) circuits used in radars but currently used in sonar.
sensıtıve time control

The effects of this are mentioned in many sources, but I will briefly tell you what benefit it provides.
After sending the signal, it becomes active while stc is passive. You will have a slow automatic amplification of the water from top to bottom and avoid saturation of the system from strong echoes. I am preparing

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