Sensitivity differences from GPS to GPS

[GeoBobC]

I've owned a dozen or more Garmin units over the years, and it's always perplexed me how two seemingly similar units can vary in their performance.

 

I've owned a 62s since 2011, and wanted a "backup" since the 62 is getting older after years of heavy use. I purchased a 64s a few months back. I've now done about 15 side-by-side tests of both the 62s and the 64s on trail runs. The 64s tracks are inferior to the 62s tracks. I've tried with GLONASS on, and off. The results are the same.

 

Is this an inferior unit? If I purchase another 64s will it be the same as the one I have? If I purchase another 62s (harder to do now), will it perform as well as the 62s I have?

 

Why is there so much variation?

[+Timpat]

My Garmin ownership is very much like yours having owned various GPSrs over 15 yrs. I also have been using my 62s for yrs and recently picked up a 64s for similar reasons as you've stated. I've been using them side-by-side to compare and in my case have found the 64s to record excellent tracklogs comparable to those from my 62s.

[GeoBobC]

Thanks for the information. I bought it online at GPS City. Too bad I didn't purchase it locally so it could be exchanged.

[+Mineral2]

In what way are the tracks on the 64s inferior?

[GeoBobC]

In what way are the tracks on the 64s inferior?

Significant variation from where they should be. For example, on an out and back trip the two legs may be 75 feet apart in places.

[+ecanderson]

There are clearly differences in performance. I have two Oregon 450 units, and my regular caching buddy has one as well. All are at the same firmware level. Sitting in a triangle on the ground in open sky, spaced about 2 feet apart, they often produce distinctly different results with regard to both EPE and distance/direction to a cache whose coordinates are ~30' distant from the center of the triangle. The differences aren't terrible, but they are significant.

[Grasscatcher]

GBC,

 

FWIW these are my opinions and mine alone, and are not intended to create any arguments.

They (the opinions) have been arrived at over multiple years, multiple units, while mapping literally several thousand miles of trails / tracks.

 

"Sensitivity" may not be the correct term. What you are probably looking for is "accuracy" and repeatability of results", correct?.

 

Between models you have to contend with different software, different chipsets, different antennas, etc.and the way those components are married together.

 

I have carried as many as 5 units (different models) simultaneously (and multiple trips also) on single track trails in difficult terrain to try and determine what works the best and why.

 

Short answer, there is no single "best" combination of settings for multiple units.

 

For track logging,some time you need to use "time" interval and other time you may need to use "distance" or "auto". (Auto-most / more often is probably the best compromise).

Time - 1/sec is good, but only for "actual path traveled" but not length /distance traveled. This logging interval is ALWAYS longer than ACTUAL distance traveled.

 

So, what that means is that to get the most accurate track, you may have to carry multiple units and each with different settings and then combine the results.

 

Carrying position is also very critical , especially in the case of multipath error. Sometime the user actually "wants" to use their body to block reflected signals from nearby cliff walls or buildings.

 

Sometimes, sensitivity is a bad thing, like when a "birdnest of random points" is logged while stopped or reflected signals are received from multipath.

Editing, or different settings, or not stopping can fix that. Using an external antenna can both help or hurt results depending on models and conditions. Think about this, if you put an external antenna (patch) on a unit with a quad helix internal antenna, what you have just done is "dumbed down" the sensitivity but might be able to place the X ant in a better position for signal reception.

 

Experiment with different settings and carrying position and you can probably find the right combination where both units compare favorably......at least until the next software/firmware update and something gets changed....then you get to start "playing" again

[GeoBobC]

Thanks for the input.

 

Carrying position is not the issue. That's been eliminated. Track log settings have been changed and tested, and can be ruled out. Addition of an external antenna should not be necessary when one model without one performs admirably. They are both quad helix models.

 

There is something inherently different in this particular 64. The question is whether or not all 64s configured identically would perform the same. If everything else is equal, how much variation is normal from unit to unit?

[+BAMBOOZLE]

I've owned a dozen or more Garmin units over the years, and it's always perplexed me how two seemingly similar units can vary in their performance.

 

I've owned a 62s since 2011, and wanted a "backup" since the 62 is getting older after years of heavy use. I purchased a 64s a few months back. I've now done about 15 side-by-side tests of both the 62s and the 64s on trail runs. The 64s tracks are inferior to the 62s tracks. I've tried with GLONASS on, and off. The results are the same.

 

Is this an inferior unit? If I purchase another 64s will it be the same as the one I have? If I purchase another 62s (harder to do now), will it perform as well as the 62s I have?

 

Why is there so much variation?

 

I don't own a 64S ( yet ) but have 3 - 62S units and there can be a big difference depending which firmware you use...the very latest might not be the best.

I read every post in this forum and my take is the 64S , while having more bells and whistles , hasn't caught up with the 62S.