Sound, Ultrasonic waves: Distance travelled and spreading angle [closed]

Question

I am working on a project related to measuring distance using sonic/ultrasonic waves(i.e. sending a pulse and calculating the time between the echo and then distance). I was reading a lot about the optimum frequency that I can choose for getting a sufficient maximum range lets say 100meter measurement. There are few things that i want to ask:-

1. How much distance can these waves travel so as to generate enough echo to be detected.
2. what are the factors affecting the distance traveled by these waves.
3. what is the spreading angle of these waves and is it possible to generate a wave of narrow angle?

I am working on getting the water level height from top of the surface, where a narrow beam would be sent and the reflected echo would be used to find the distance divided by two to get the actual height.

Note that the diameter of inlet is atmax 10 inches and hence a narrow beam is needed. for the start however the spreading is not an issue for me since it is just for the test purpose.

thank you in advance.

Answer 1

1)"How much distance can these waves travel so as to generate enough echo to be detected." It depends on your receiving transducer and electronics noise levels, among other things.

For attenuation in air see: https://physics.stackexchange.com/a/52246/45664

2)"what are the factors affecting the distance traveled by these waves." Attenuation will be the primary factor.

3) "what is the spreading angle of these waves and is it possible to generate a wave of narrow angle?" The unfocused beam width in radians is approximately given by the wavelength divided by the aperture width. (more true for continuous rather than pulsed transmission) So you can make a narrower beam by increasing the frequency or increasing the aperture size (also by using some focusing). It is possible to have a narrow beam.

See: http://www.ndtcalc.com/utbeamspread.html