NJRonbo

For the first time since taking delivery last July, I drove my
RL from my home in Central NJ to New York City.

I had the navigation unit running the entire trip.

I was suddenly amazed the moment I entered the Lincoln Tunnel.

While I expected my XM radio would cut out, I certainly did
not expect my navigation unit to continue tracking my position.

That navigation unit charted my progress the entire trip through
the tunnel under the Hudson River (glub! glub!).

I was just amazed that the navigation unit received a signal
under those circumstances.

Rich in NC

It didn't receive a signal. It has a gyrocompass and inertial guidance to fill in the gaps. Honest!

CGTSX2004

iTrader: (1)

Or something along those lines. The system is indeed to be able to operate without exact guidance when a satellite signal is not available.

jftjr

It doesn't even need a compass.... it knows you were on that road, and the distance travelled. Not like you were going to be getting *off* that road in the tunnel, huh?

gbriank

I think it was the fluxcapacitor that kept everything working... You know those darn Japanese, they've figured everything out...

NJRonbo

gyrocompass and inertial guidance?

I am learning something new all the time.

Pretty amazing stuff.

Anyhow, it guided me through that tunnel quite well.

SodaLuvr

Navigation related discussion, thread has been moved to the appropriate section.

Nocturnal

The system should indeed have 'dead reckoning' backup to the GPS system. That should also allow for decent performance when mountains/trees/buildings temporarily block the GPS signal. I doubt it uses gyros but a compass combined with accurate speed information is enough to keep it reasonably accurate for a while.

I still wonder why they didn't put the GPS antenna in the sharkfin though. That's where it belongs for best reception potential.