There is a simple algorithm on Wikipedia: how to build ultrasound image. And I want to build one. Resolution and presision are of no importance, I just want to do this for the case of study - I want to make such an "image 1D+depth slice" of a 20m^2 room. So I may just use these low frequency sensors - 1cm is enough.
So, as stated in the article, I need a phased array (to direct wave). And accidentally I have a couple of Arduino sensors HC-SR04:
Everyone uses them, but I stumbled how to use them. Interface seems to be totally weird, insuffient and unusable. Despite there are (visually) so many logic ICs soldered on the back.. So why is it designed so poorly and how to fix that?
Could you help me - where and what would you solder/desolder to use it for ultrasound imaging? I think that sensors itself could suit for this task.
PS. Basically I need to measure echoes delay (for depth) and echoes streight (for pixel brightness)
It should work on the phased array principles, without rotating, moving, without using any motors. Desired radiation pattern is illustrated by following animations:

