Couple of cool navigation and Hidden screen tricks!

Well, the actual decimal conversion would be 42.532778. I tried plugging in a couple points in ArcMap one with your 42.3158 guesstimate and the other the real conversion 42.532778 and used the same longitude for both. And the two points were 15 miles apart in the northerly direction.

 

Wow, I did a double take on this one! Didn't realize maps were too technical for women to understand. We do go to school too like the men folk!

 

Well! Lots of responses!
I know as many have said that the GPS system is, or should be accurate to a matter of feet. I don't know exactly the figure and it could vary, but I mean at least within sight distance.

I checked the Prius NAV with the Garmin inside the Prius.
The seconds were off by up to 30 seconds.
Example:
Pruis N38. 56.32 W 27. 42.12
Garmin: N38. 56,452 W 27. 42.137

Prius only displays two final digits and Garmin displays three.

I just used imaginary numbers here, but you get the idea.
My experience was that the seeming small difference in numbers was about two blocks South and one block East of my location in Prius while Garmin was trying to locate me.

Also these differences do vary. changing locations will change the variance, so it is not a matter of adding a value to one device to compensate the difference.

I do not know of a way to change the map Datum as mentioned earlier on either device.

I was wondering if Toyota would be any help. Seems doubtful to me.

Just frustrating as I do not know why this is happening, and I don't understand.

 

Assuming you mean there is a calibrate setting on the Prius, could you point me to that setting? It may be that simple to make an adjustment.

 

The difference between the Prius position and the Garmin position is easily explained:
The Prius shows its position in degrees, minutes and seconds.
The Garmin shows its position in degrees, and minutes with a decimal.
For example if the Prius would show 54 21' 30''
Then the Garmin would show 54 21.500'

 

Windstrings:
I think I have done that calibration setting. While at home, since I know where that is, and should be on the map, I set it to show Home where the Prius is when parked in my driveway. I do notice though when I did that the address does not show correct when displayed at the top of the map. (I think you push "map" while in map screen to show this) So maybe that is part of the issue, but otherwise it showed my house had moved. I believe I saw that when I had entered "Home" as an address, the map showed my house down the street from where my car was parked when in the drive, so I adjusted it to show the car's position as "home!"

Sho-Bud:
I understand the decimal versus seconds in terms of figures.
Does that mean the Garmin, using decimals, would always round off to the nearest whole decimal setting on the seconds?
I am wondering now, How far is a second?
Could a half a second be a couple of city blocks?

I am not sure how, or if, that could be compensated, but could explain the difference in using plain coordinates between the two devices.

Thanks for everyone's information! This is getting interesting.:thumb:

 

+1 Agreed.

Nortnarg,

On the Garmin, this is not a Map Datum setting problem but a Position Format setting i.e. h dd mm.mmm is currently set and it would need to be change to h dd mm ss.s. If it helps, Garmin have their Owner's Manuals available from the Garmin website.

 

It depends on where you are and whether you are talking about Latitude or Longitude and more likely a vector(? I'm not hot on maths) of the two.

I've been using Excel to play with the Simple Spherical formula from the following web site for the last few days!

Calculate distance and bearing between two Latitude/Longitude points using Haversine formula in JavaScript

EDIT: Hopefully, I've managed to attach the spreadsheet that I've been playing with. The data entry should be confined to entering the Latitude and Longitude. I've used Lat & Long for London, UK (as given by wikipedia). i.e.
N 51 30 28 W 00 07 41

The sheet is split to answer two different questions. The top half is for saying given two Lat and Long what is the distance between the points. The bottom half of the sheet answers the question if the first Lat and Long numbers convert correctly and the 2nd Lat and Long are converted incorrectly what is the distance between the two - it makes more sense to type the same Lat and Long for this bottom half of the sheet.

I am sure I haven't explained myself at all well.

 

Thanks for your help Timberwolf!

I got the excel sheet and will study that. At first glance it is way over my head, but did find some interesting info on the website.

I think I may have found the cure. You suggested to change the position format.
I pulled out the Garmin .pdf manual and there is a setting to change the type of coordinates. So, I will check on that!

Unfortunately the Garmin Nuvi 265 is in Chicago this week, and I am in Missouri.
Will certainly look at that when I can.
I doubt there is a setting on the Pruis to change format, but looks like I may get lucky on changing the Garmin.

 

Theoretically, the position shown with the coordinates on the Garman is more precise.
On the Prius nav every minute is devided in 60 seconds, on the Garmin every minute is devided in 1000th. One second would be about 0.017 minute

 

Great!
Changing the format on the Garmin did the trick for me.

Going to format on the coordinates makes it match the format of the Prius.
The format looks like this: h ddd mm' ss.s'
the decimal in the seconds is beyond what the Pruis will show, but I find that to be within 2 tenths of a second matching the Prius.

That is getting both devices together in my driveway.
I will do a more useful test when I get out somewhere and can separate the two devices and try to find each other.

This looks to be just what I needed to play my games! Kewl!

Thanks to all who were a help in this.

 

The hidden service screen the 2005 Prius displays the seconds to 2 decimal places. The nav screen does not display decimal seconds.

Also, coordinate destinations are inputted on the 2005 using the ddd mm ss format not ddd.xxxxxx. The input format was apparently changed at a subsequent model year.

 

Good info,
I took both devices for a spin today, and found them to be consistent with each other. The decimal or partial seconds that the car does not show could make you off by at most 40 50 feet in my totally unscientific test.
That is close enough for me to do what I need. Let the games begin.

Of course my main computer died on me today so that is taking too much of my time now . . . always something!!!