Crunch time for DiveLine

[Manjula Ellepola]

LViz you are right, noise is always a problem. Having a down ward looking DVL might solve these problems as you are measuring to a fixed reference. We would also have other sensors like compass and inertial to aid in the calculations. For sure it is an extraordinarily complex problem that has eluded a viable and practical solution all this time

 

[Manjula Ellepola]

Ok understand about the spool...what is the risk of entanglement once there is slack on the line as you mentioned above?

 

[lowviz]

OK, so now you have half a chance. Compass, an inertial sensor that gives you a parametric equation describing what it felt, and your doppler direction and magnitude. Need one more, you still can't deal with 'drifting with the current'. Once you get that, you have a nightmare in software to contend with.

 

[lowviz]

No diver entanglement. It just wraps around the spool and jams if you don't free it before you start moving again. Just a nuisance.

 

[Manjula Ellepola]

LWiz I think if we were to have downward looking DVL then the drift can be estimated ie the DVL will measure the resultant vector of the swim and current relative to the bottom. Yes you are right lots of digital signal processing

 

[lowviz]

Can't make one sensor do three things. Either water speed or 'ground speed', but now you are restricted to having a hard bottom. Use an independent sensor for that, if you have no bottom then it gets ignored...

 

[Manjula Ellepola]

If the spool is motorized and have a sensor for tension on the line might be nice ...

 

[lowviz]

Many have tried, many have failed.

 

[Manjula Ellepola]

Yes true re the sensors...how ever got to be careful the diver doesn't end up looking like a Christmas tree

 

[Manjula Ellepola]

you mean the motorized spool or navigation device?