On a rocking sail boat it should be as accurate as an eggcup type. I have used the same response time constant.
why the ZCD has a pot R 22 ?
We want to detect above the noise level and I want it to occur before the envelope detector. An improvement would be for the ZCD to be fixed and the envelope to be adjustable.
D1 , on the envelope detector.
This is not a rectifier but an Amplitude modulation detector. A precision rectifier would bring the detection level down but I dont know if it is really necessary.
On the 4052, why we need -5 V?
This may be a bit of overkill as the negative voltage on the analog input is very small(it can cope with -5v).
You should try to leave it out and see if it works for you.
What I mean if we send pulse 1 , the corresponding reversed pulsed will be after 300 other pulses
Yes but remember we are getting an average over time.
Also I found that you need a couple of pulses before the circuit becomes stable(I drop the first couple of measurements).
It looks like if the diff is less than 200 (ie half period), then you add a pulse.
I need some more information to answer that.
about transducers behavior and define Northerror .
Now this was just trial and error and I chose 20 as a reasonable figure. This is an area were there could be much improvement.
Even you mentioned that we do not have individual Tof, I think we do have it, since envelope measures that
Yes we do not have an accurate figure for tof to use in that equation.
Keep me informed on your progress.
I am going to revisit this design as my next project but I will be busy on another project for some months.