Rand McNally intelliRoute TND 500

Here's a weird one. I went to sleep with my TND saying 677 miles to my customer. And when I woke up it says 591 and it is displaying the Same route. I will let you know what happens.

 

As soon as you get back on to route it will revert back to 677 miles. This happens almost any time you go off grid, say for example into a truck stop.

 

The current database will not be corrected. Whenever a address change is in, it has to verified and corrected. This will always show up in the next mapping database. If RM has to submit to NavTeq, then the process may take longer.

I am reforwarding to RM.

thanks,
Mark

 

Forwarded this to RM and to the engineers... sounds like odd routing...

What do you have set to avoid? Remember - version 1472 you cannot have anything set to avoid in route settings under preferences. Their is an issue and it has be resolved in the next version.

Thanks,
Mark

 

I'd also point out that detour and avoid are two different things. Detours will clear themselves, avoids will not.

 

I caught that after thinking about it, I figure it is showing air miles if you are not on a recognized road.

 

I have no avoids and I have not used the detour function at all.

 

It might be doing what mine just did and has done in the past. I was rolling up I-65 North of Louisville,KY and mine started telling me to get off and make a left ,then get off make a right , then a Uturn. I looked at the screen and the gps had me running out in a field and I think it was trying to get me back on the road (even though it was the TND's own mistake that I was off the road).
It seems to lose where I am and then get an incorrect position and go haywire trying to reroute me. I've had it showing that I was running parallel to I-40 about 20 miles north of where I was for a good 30 miles.

 

Note: We found that if the GPS signal is weak, it can do what you describe. It can sometimes be "on the edge" of seeing the satellites and can cause what we have termed as "dementia" here in our tests. What happens is that it has a view of a couple of the satellites but not a "strong track" for a moment or even a minute or two. In order to have a 3-dimensional "fix" the unit needs to have a solid signal from AT LEAST 3 satellites at any given time - a preferably many more than 3 in reality.

Symptoms of GPS dementia:
1. The screen shows your vehicle offset from where you actually are. For example, it may show you on a frontage road or side road running parallel to you instead of the one you are on.
2. The screen shows you "off in a field." This is where it'll show your vehicle off the beaten path entirely.
3. During moments of signal dementia a GPS will attempt to tell you to take turns, turn around, detour, etc. because it thinks that you are no longer on your prescribed route.
4. When this does occur, we find that it is usually for less than a minute before it gains back enough signal strength to get "back on track" but during that "lost" period it can be very disorientating and in extreme cases can lead you to the strong desire to break things.

Causes of GPS signal dementia:
- GPS hardware: what brand of receiver that the manufacturer put in the unit.
- GPS software: depending on what it is doing - how much it is "thinking about" at that given moment and how the programmers wrote the code, we have seen them momentarily show a position error until it "catches back up" with whatever it was doing at that time.
- Satellites: It has actually occurred whereby the government satellites have glitched and resulted in temporary signal loss or bad position data.
- Weather conditions.
- Your truck: every rig has a unique signature that dictates how much signal can get through. Certain factors (especially those big chrome visors) can decrease the signal. Also, the amount of electrical power running in you cab and how many watts your CB is can affect the signal.
- Blockage of the sky. Trees and mountains, and especially tall buildings, bridges, and tunnels. In fact, drivers who spend a lot of time in New York City or other "mega" urban areas will experience signal loss and position errors at times.

How to check the signal: All of the brands have a screen where you can check current signal strength. I the TND, it is under "Main Menu / Preferences / GPS Data." It will show you how many satellites that it currently sees. They say that you need at least 3 to have a 3-dimensional fix on your position, but we found that you will normally see 8 - 11 of them under good navigating conditions.

How to fix position dementia: use an external GPS receiver. It plugs into the back or side of the unit and goes up on the dash (or even outside of the rig.) With an external receiver we almost never see a position problem related to satellite signal strength.

All of the units we tested have experienced signal dementia under more extreme conditions - especially when in a car-hauler (with a car over the top of the cab) and in New York City. It is not specific to the TND. In fact, the Rand McNally TND-500 model showed to have one of the best receivers we have tested when it came to our New York City tests, but it still experienced periods of positional lag or dementia there just the same. The Garmin 465T and the PCMiler 430 models do not have external receiver connections but the TND, all other PC Miler models, and the Cobra units do. Normally the built-in receivers are just fine, but if you do some experimenting while watching that signal-strength screen in any of the brands, you can usually determine if your rig or your driving routes may be benefited by an external receiver.

Just something to ponder if you are experiencing position issues at times on any GPS.

 

I have noticed that when the TND is doing that, there's no problem with the 465t. The TND always lags by a second or two, just watch the speedometer. The altitude seems to read about 120 feet higher than it really is all the time too.