Hi All !

This is going to be a very interesting project. It's about a 3D SONAR or an Acoustic Camera. In order to make it viable (budget wise), it's going to be done using COTS (Commercial Off The Shelf) products. It will use low cost Fish Finder Electronics and Transducer (like Lucky 1108-1).

The main principle is the Interferometry between elements of an array of transducers. In our case it is going to be an array of 6 x 6 Transducers.

It all starts with the mount of the transducers, and for that, it is necessary a good means to hold them and to stack them in an array fashion. Lego principles are applied here. Well, for that, the nut that is in the picture (Tuerca8) is the proof of concept of this mechanism, the cornerstone for the whole setup.

Once this is tested, a more complex shape is to be built and in a more robust material (Nylon and Carbon), where rubber cavities are to be included as a sound dampening mechanism (to reduce vibration and unwanted interference)

Arranging and interlocking each piece of the puzzle is going to produce the required array.

On next posts the new shape is to be presented and a blueprint of the finished array.

In the meantime, let me tell you about the Camera per-se. It is based on the principle of insonifying a certain volume and picking up the echoed signal by an array of ultrasound transducers. Two important things we get here:

1) The time of flight of the soundwave in water (1500m/s) determines the distance to each object that reflects the sound wave

2) Each object/s feature represents a source of sound, as seen by the array of transducers.

Interferometry is the same principle/mechanism that is used in Radio Astronomy, where each star in the firmament represents a source of energy and several antennae pick up those signals. Digitally steering the reception (delay and sum mechanism), we can digitally direct the sensitivity of our array to a particular direction inside a solid angle.

Digital Signal Processing takes care of reproducing the image by stitching each element's representation in the time domain and presenting that as a 3D Point Cloud.

As every journey, this one starts with a small step. The Nut.

Stay tuned, more to come.