Hey guys, this is my first experience with NAV in my own car, so I wanted to check the following behavior is normal:

When I approach my destination, it says 'You have arrived' when I'm still about 50-100 yards from the destination. This can be tricky when the destination is somewhere new to me, so I have to start frantically looking around in the general area to locate the place I'm looking for. It can be very tricky if the dest. is a small business in a shopping center or strip mall.

Am I expecting too much for it to pinpoint the exact location?

 

Yes, it's not a substitute for your brain.

 

Guess you have low expectations from your technology...

 

I've driven cars with many types of naviagion and none of them really 'took me to the door' like you're asking about. It gets you in the very near vicinity... sometimes more accurate than other times, depending on the map software and other conditions.

You guys be friendly please. We foster a sense of community on CL and have rules to that effect.

 

What is the specs for the Lexus NAV? Most navigations I've used state it is only accurate to within X amount of meters or feet. 50-100 ft is a little long, but not too bad. Usually they state somewhere between 5-15 meters I believe.

 

i usually have the map almost all the way zoomed in. you can see when the lady says you have arrived that you are still far from the Destination dot. i think another reason they announce in advance is because she speaks pretty slowly, but if you are traveling 50 miles an hour on a busy street, the dot won't just pass you by once she has spoken her last word. i tend to keep an eye on the arrow approaching the dot, and more often than not, the dot is right on the money.

 

Thanks guys, I'll remember to try the dot thing next time.

Also, sorry about my remark to 32kcolors, just couldn't resist such an easy put-down

 

The Nav system in my RX is actually more accurate than my laptop-based GPS program - by a dozen yards or so - downrange of your observed position, although the crossrange error is almost zero. Like the triggering of the voice module, this is probably an artifact of trying to "anticipate" your arrival at the fixed point. Software manufacturers seem to differ slightly on this factor. It really isn't critical, since once you are aware of this "error", you can anticipate it.

There are errors that appear in all GPS software applications that incorrectly count off street addresses. I've seen a few sizable errors (a city block or slightly more), particularly in rural areas where streets are not reliably marked. Since these maps are generated from aerial maps, precision in the address location is often more a factor of local numbering conventions than actual distance.

A few years ago I was looking for an address that was shown to be in the middle of a railroad track. This was before Nav was an option on the RX, and I was using my laptop to locate the customer's office. As it turned out, some seventeen blocks of Hillcroft street lay between one side of the tracks and the other at Westpark. It was a numbering error by the city, that simply counted street numbers south from one position, and north from another - the discrepancy was corrected by deleting those 17 blocks of street numbers where they met - at the tracks. The office park I was seeking was a block away - actually mis-numbered by the builder, who evidently counted out the blocks for himself and posted HIS number on the building. The City never caught the error, despite the fact that a popular restaurant a block away was (on paper) some ten blocks distant.

I guess Nav doesn't solve everything . . . :

 

Srashid-

You might want to play the Nav Intro CD ROM that came with your vehicle in your computer (or just the audio portion in your CD player). It actually answers some of the frequent "surprises" that you encounter - like this one and why house numbers may not be on the street where you think they are.

If you did play it when you first got it, it might be more meaningful to you now that you have played with the nav for a while.

 

I remember reading the NAV manual and it states that "you have arrived at your destination" is announced way ahead of the actual destination to allow you to start finding for a parking spot right before you reach the destination. Normally it should not be very far from the actual destination.

 

It does announce arrival a bit sooner than I'd like. About 100 yards away from the actual spot. Note that the NAV itself isn't always precise on the street address anyway. Sometimes it's dead on, sometimes it's 300 yards away.

 

I almost worked on GPS system in school. The preliminary information I gathered then is that DOD (yes department of defence) scrambles the GPS information and comercial equipment was only able to get it down to within 10 meters in x/y and altitude was within 50 meters. Since then the technology has advanced and the comercial receivers started doing averaging and if the receiver was not moving, it could get it down to less than a meter. Within last couple of years the scrambling has been backed off and now the number is close to 5meters.

Then on top you have map issues. Street addresses can be off specially on a curved street. The street numbers although look sequential but are grid based.

Modern gps recivers also use pseudo dead recognition based on rotation of the wheel from a known last mulitple sattelite reception point.

Over all the stuff if neat, but it can be off. That is why you will see a disclaimer ... it is only an aid ...

If you dig through old posts, the new systems are far superior ..
Old sytem at times would show you are driving over ocean instead of hwy 1.
Old sytem will create the route but when you get near the destination it would be blank as it was unable to REALLY find the destination.


Salim