The next step to take in determining the feasibility of a sonic altimeter is to test the reception of the echo while generating noise similar to that produced by an aircraft. It might be impossible to identify the received echo if a lot of noise is generated in the 8-12 kHz range. If this is the case, DSP will need to be incorporated in order to further clean up the received signal. This could be tested by recording the output and applying a DSP algorithm through Matlab or a similar program.
Should this step prove successful, the final step would be to add a microprocessor to the system. The microprocessor would be used to generate the original pulse, apply the DSP algorithm to the received signal, make the necessary calculations in order to determine the distance measured, and output this value on an LCD screen.