Jump to content

Garmin V vs. Garmin V....


Alphawolf

Recommended Posts

Just a curious observation: Yesterday, 2 Garmin V's, side by side on the dash of my car. Both with 2.08 firmware. The speeds are identical while moving. Down to the 1/10 mph. However, sitting still in my driveway, the altitudes varied from dead-together to about 100 ft. apart. Not that I care one bit, but it seemed curious. Same units, same firmware, same satellite signals, same time, same everything, different altitudes.(I know....get a life! You see I sell these things, so I can do stupid stuff like this!)

Link to comment

quote:
Were the altitudes in sync while they were moving ? Or were they different only when standing still?


The altitudes were different while moving and while stationary also. At times, the would be close, but then would spread apart again. I might add that WAAS was also disabled on both. Pretty intriguing huh?

Link to comment

quote:
Originally posted by Alphawolf:

The altitudes were different while moving and while stationary also. At times, the would be close, but then would spread apart again. I might add that WAAS was also disabled on both. Pretty intriguing huh?


 

Well, there have been messages on here that have indicated that the altitude readings tend to bounce around. This being reported on a number of different brands and models as I remeber. I guess Altitude is one of the harder things to calculate.

 

My only observation is while driving through the mountains to california and back (from Chicago) that every time we crossed a summit that had an Elevation sign, my GPS5 showed almost the same number +/- 20 feet or so. I was using an external antenna on the car roof top, so almost always had 8 to 12 satalites locked on. Here in illinois where things are basically flat, you dont see alot of changes in altitude, but driving through the mountains on some of the steep roads the numbers would run up or down close to 100 feet per minute. Only had the one V, so had nothing to check it against.

-Centaur

 

logo_small.jpg

Link to comment

I would assume that even sligth occurences of multipath and other disturbances to the signals, may cause one unit to interpret nearly the same signals different, compared to another one, that's nearby.

 

After all, they do make readings at regular intervals (one second, if in normal mode). Since they aren't synchronised, these readings doesn't occur at exactly the same time, so sporadic noise may not cause the same problem in both receivers.

 

Since the altitude is more sensitive to the signal condition, due to the less favorable geometry when determining positions vertically, it may also show a larger error due to such noise, than the horisontal position.

 

Or does anyone else know about a better explanation?

 

Anders

Link to comment

You have pretty well surmised my guesses as to why the variance. Again, I could care less about it, it was lust a curiosity. I have too, noticed an amazing accuracy potential of the altitude readings when comparing them to known altitudes, such as marked passes in the mountains and such. Hey...I just imagined a new test! The V, a MAP 76S, a Vista, a Meridian Platinum all lined up on my dash! (I have access to them all) Of course, I would need a "navigator" to help me, or a driver, while I did it. icon_razz.gif

Link to comment

You have pretty well surmised my guesses as to why the variance. Again, I could care less about it, it was lust a curiosity. I have too, noticed an amazing accuracy potential of the altitude readings when comparing them to known altitudes, such as marked passes in the mountains and such. Hey...I just imagined a new test! The V, a MAP 76S, a Vista, a Meridian Platinum all lined up on my dash! (I have access to them all) Of course, I would need a "navigator" to help me, or a driver, while I did it. icon_razz.gif

Link to comment

You might also consider that anything that receives radio signals is also capable of transmitting them. It is possible that having the two units so close together they were causing interference with each other.

 

Just a thought.

 

----

Duct tape is like the Force. It has a light side and a dark side, and it holds the universe together.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...