[PSUBS-MAILIST] Re: Snow White virus

["Michael B. Holt" <mholt@richmond.edu>]

"Sean T. Stevenson" wrote:
> 
> Perhaps  you could explain exactly what your intent is...  DR
> navigation while submerged with brief surface intervals to update
> your position via GPS, or continuous submerged electronic navigation?

Continuous would be good, but it's not necessary.

> The latter can be accomplished by combining (correcting?) the NMEA
> data from the GPS receiver with acoustic positioning of the receiver
> relative to the sub.  DR can also be supplemented by inertial
> navigation, although that can be a bit expensive. 

Yeah, let's avoid "expensive."  Acoustic position of a buouy is
a bit more complicated and expensive than I had in mind, too.

What I had in mind is a DR track that was corrected by GPS
checks every hour or so, depending on known currents and the
like.  I don't expect this can be hard to do; it's probably
already out there.  I would expect to find that sort of system
built into high-end GPS units.

> What sort of accuracy do you need?

Just good enough to stay out of the way of traffic that can be
expected.  It's not like I'd ever need to know where I was within
ten feet.

I suppose we'd have to call it Snow White navigation, now ....



Mike