Whatever happened to dead reckoning?

Is dead reckoning, well, err, dead?

It seems that Garmin is not selling GPS with dead reckoning anymore.

Does the competition have it?

Not that I care much for it. I have driven in all the big US cities and
the only one where you really need it is in Manhattan.

-Ramon

It's alive and well but mostly in built-in car systems and in-dash
aftermarket units from Pioneer, Alpine, etc.


The 7500 has it.


Cheers,
John

--
\ carpe cavy!
seagull @ aracnet.com \
http://www.aracnet.com/~seagull/ \ (seize the guinea pig!)

Ramon F Herrera wrote:

You mean DED Reckoning - Deduced reckoning - taking a SWAG as to where you
are. DEC Reckoning is one method of navigation, GPS is an aid to navigation
where one gets occasional (with good signals Quite Often) fixes.

Ded Reckoning - hmmm I started at Point A, went (about)northeast for 10
minutes at 35mph, so without anything putting me off course I should be at
Point B - Now let's get a Fix, and see where I really am. hmmm, close. Ok
correct my course and/or speed guess and go from Point (new)B towards C.




--
Mike Vore
http://www.OhMyWoodness.com
http://mike.vorefamily.net/twr

mike vore wrote:

No, "dead reckoning" appears to be the correct form, at least according
to the Oxford dictionary eytymology and Wikipedia:
http://en.wikipedia.org/wiki/Dead_reckoning
Calling it "ded" for deduced seems to be a rather recent corruption of
the previous term.

Most GPS units have some form of dead reckoning, e.g. Garmins generally
continue showing your position incrementing as it was before for 30
seconds after a loss-of-signal, and many of the built-in automotive
units have a more sophisticated dead-reckoning feature using magnetic
compass sensors and a speedometer output to continue navigating while
in tunnels or in tight urban (or natural) canyons where reception is
blocked for extended periods. Of course errors will eventually build
up and make such navigation inaccurate, but it can be of significant
help in some environments.

Garmin has been offering this enhanced dead-reckoning feature on some
of their automotive models starting with the 2650/2660, but I don't
think it ever captured much of that market. Since it required physical
connection to the car wiring Garmin first insisted that those units be
purchased only from authorized installers. That made the units
relatively high-priced compared to their other models which were
subject to more competitive pricing by dealers.
Their current 7500 model has simplified the process so dealer
installation is no longer needed.

Better GPS receiver circuitry has also reduced the need for the
enhanced dead-reckoning feature.

peter wrote:

I thought some of the TomTom models had dead reckoning via internal
sensors -- i.e., no need to hook anything up.

I was disappointed that my new (and otherwise awesome) Nuvi 660 still
says "Lost Satellite Reception" when going through tunnels. It should
know how to calculate when I enter the tunnel going X mph, and the
tunnel is Y miles long, generally how long it should keep its clap shut.
In that respect it acts just like the SPIII did back in the Jurassic
era.

--
JC