| Chalky |
05-17-2014 06:00 AM |
Quote:
Originally Posted by KiwiJochen
(Post 714432)
The speed pulse is needed for dead reckoning
Dead reckoning is used...
for the first seconds to minutes after switch on before a GPS signal is acquired (you can easily drive 1km in this time)
under bridges
in tunnels
in underground carparks
in built up cities with many skyscrapers and poor satellite reception
in very bad weather with weak GPS signal
and many other situations where GPS signal is interrupted.
Use at the VERY LEAST the speed pulse!
The reverse signal is only for when you go backwards.... but that is so easy to connect, there is no excuse for not using it.
No Dead Reckoning = Disappointing GPS performance
With Dead Reckoning = Perfect GPS Performance
You choose.
|
Jochen is right, initial time to find a satellite fix can be considerable, and with speedo/wheel signal your nav computer will be useless for that period, instructions will be rubbish. I experienced this last week in my own car (E38 nav retrofit), it was embarrassing. Then, I connected up the speedo signal (TAA), and I was very impressed. I suddenly had navigation directions immediately available upon entering the car, prior to getting proper GPS fix! The nav computer's tracking based on speed signal, compass, & gyros is quite amazing. It really was like another upgrade to my nav. Love it. |
