OK you technology people...explain this...

[DavePelz4]

One of my golf buds and I have the exact Garmin G6. They're both current on the software updates as of 5/27.

 

So...today...we were 4-7 yards off when standing the in the exact same spot with Garmin in hand. OK...we're not tour pros and 12-21 feet isn't that big of a deal but please enlighten me as to why this could happen.

 

Just to make this even more entertaining, we both turned off our Garmins and restarted them while standing in the exact same place yet the 4-7 yard difference stayed consistent.

 

Thoughts???

[bhard315]

Buy a rangefinder.

[Fade]

Interesting. Was one of you always short, the other always long, or did that vary, for example based on the direction the hole was playing in?

[snoilr1]

4-7 yards different from each other, or 4-7 off course markers, but the same as each other?

 

For GPS to get a reading, you have lock onto at least 3 satellites, and improves the more you can get. If it was cloudy, or you were in a heavily treed area, it could be one, or both, of you weren't locking onto the same number of satellites. That could explain why you weren't agreeing with each other, or why you were off.

 

If you were both getting the same reading, but not matching the markers, it could be the markers are off. The course I play the most, my GPS is within a yard or two of every marker, except one par 3 where I'm always 7-8 yards off. Based on the yardage I hit my clubs on every other hole, my GPS is right on that hole.

[tdelam]

4-7 yards different from each other, or 4-7 off course markers, but the same as each other?

 

For GPS to get a reading, you have lock onto at least 3 satellites, and improves the more you can get. If it was cloudy, or you were in a heavily treed area, it could be one, or both, of you weren't locking onto the same number of satellites. That could explain why you weren't agreeing with each other, or why you were off.

 

If you were both getting the same reading, but not matching the markers, it could be the markers are off. The course I play the most, my GPS is within a yard or two of every marker, except one par 3 where I'm always 7-8 yards off. Based on the yardage I hit my clubs on every other hole, my GPS is right on that hole.

 

I was going to say this but he beat me to it. You're using GPS technology, there is definitely going to be differences like that. Need a rangefinder :)

[Lenny7]

Silver fillings?

[DavePelz4]

Interesting. Was one of you always short, the other always long, or did that vary, for example based on the direction the hole was playing in?

 

Simply, if we both stood in the exact same spot, one would be 148 yards to the center and the other would be 152. One GPS was always shorter the other longer.

[Thrillhouse]

not a tech guy (maybe someone who is can confirm) but I've heard something along the lines of:

 

GPS is only accurate to +/- 3 yards because the US government owns the satellites and there is some sort of control on them (security reasons?) to keep it at that level, and if they removed that control it would be accurate to +/- 1 yard.

 

So I either heard that from a scientist, or a crackhead on a street corner yelling it at a stop sign. I don't really remember which one but it's crammed in my head for some reason.

[Qqq123xx]

Someone must have really long arms.

[MattOrris]

GPS sends out time signals that are collected by your receiver. You need at least 4 sat fixes to produce a solution in latitude longitude altitude and somewhat counter intuitively time. The more sats you have the less error should occur. The signals are actually very weak and are affected significantly by the atmosphere. The time signals must be extremely precise and the processing to pull that weak signal out of the background noise is quite complex. Most receivers in order to get a faster solution actually use a semi random guess to get started. So that ramdom guess mixed with randomness in the atmosphere produce slightly different results.

 

The us government used to degrade the signals for civilian use but processing techniques made that useless so Clinton (Ithink) ordered that degradation stopped.

[ThinkingPlus]

One of my golf buds and I have the exact Garmin G6. They're both current on the software updates as of 5/27.

 

So...today...we were 4-7 yards off when standing the in the exact same spot with Garmin in hand. OK...we're not tour pros and 12-21 feet isn't that big of a deal but please enlighten me as to why this could happen.

 

Just to make this even more entertaining, we both turned off our Garmins and restarted them while standing in the exact same place yet the 4-7 yard difference stayed consistent.

 

Thoughts???

 

Updates of the Garmin software or course database or both? If you happened to have a different date on the course information you could get differences maybe. Also there are hardware tolerances that might make a difference, but I would not expect it to be that much. Locking on to a different set of satellites between the units might also make a difference. I agree that it is puzzling.

[Stuart_G]

It's possible the course data can get corrupted when it's loaded onto the watch so just because your watches had the same course update revision doesn't necessarily mean the data in the watches is identical.

 

One day after an update (no problems or update failures reported) I found my watch was way off (10-15 yards) for my home course. I went and forced the same course data revision to be update again and it fixed the problem.

[HackerD]

It's possible the course data can get corrupted when it's loaded onto the watch so just because your watches had the same course update revision doesn't necessarily mean the data in the watches is identical.

 

One day after an update (no problems or update failures reported) I found my watch was way off (10-15 yards) for my home course. I went and forced the same course data revision to be update again and it fixed the problem.

 

This explanation sounds plausible for the systematic difference that was observed. Question: does Garmin refresh course information every time the software is updated?

(Is it possible the two devices had different course info not due to corrupted data but just different versions...?)

[Stuart_G]

This explanation sounds plausible for the systematic difference that was observed. Question: does Garmin refresh course information every time the software is updated?

(Is it possible the two devices had different course info not due to corrupted data but just different versions...?)

 

The watch software (and various firmware) revisions are separate from the course update revisions (and are reported separately). In fact the course data is broken into 3 separate regions and each region has separate revision numbers.

 

So it's possible to say update the software and not update the course info (or visa-versa) but I think it would be hard to do that unintentionally.

[DavePelz4]

We have the same handheld Garmin, same software revision, clear day, middle of the fairway, just different yardages.

[Socrates]

Another reason I like the laser. Although, the other day I was in the wrong fairway with no line of sight to the flag (or the right fairway for that matter) and it would have been nice to know what club potentially could have got me out of jail.

[Yrrdead]

Uhm +- 3yds is good for GPS. The fact that you got two tiny units showing approximately 2% error seems pretty good to me. Precision these days is great and accuracy is also pretty darn good. I'm confused at what you think the problem is?

 

not a tech guy (maybe someone who is can confirm) but I've heard something along the lines of:

 

GPS is only accurate to +/- 3 yards because the US government owns the satellites and there is some sort of control on them (security reasons?) to keep it at that level, and if they removed that control it would be accurate to +/- 1 yard.

 

So I either heard that from a scientist, or a crackhead on a street corner yelling it at a stop sign. I don't really remember which one but it's crammed in my head for some reason.

 

That hasn't been the case for years(2000). But it used to be limited to +- 100yds. Which is what prevented the proliferation of GPS technology.

[TScottTX]

Are either of you wearing or carrying other electronic equipment, pacemaker, etc.? Holding your G6 while wearing a magnetic wristband? One G6 way newer than the other? One of you drop your G6's to the ground occasionally? Are both of you batteries strong and last the same period of time? Lots of things that could account for your experience.

[DavePelz4]

Uhm +- 3yds is good for GPS. The fact that you got two tiny units showing approximately 2% error seems pretty good to me. Precision these days is great and accuracy is also pretty darn good. I'm confused at what you think the problem is?

 

not a tech guy (maybe someone who is can confirm) but I've heard something along the lines of:

 

GPS is only accurate to +/- 3 yards because the US government owns the satellites and there is some sort of control on them (security reasons?) to keep it at that level, and if they removed that control it would be accurate to +/- 1 yard.

 

So I either heard that from a scientist, or a crackhead on a street corner yelling it at a stop sign. I don't really remember which one but it's crammed in my head for some reason.

 

That hasn't been the case for years(2000). But it used to be limited to +- 100yds. Which is what prevented the proliferation of GPS technology.

 

Mrs. Pelz has issues with small units but that's a topic for another thread.

[North Butte]

Every GPS I've ever tried will disagree with itself from time to time by up to six yards or so. It is just the nature of golf GPS devices. If you care about, say, four yards of uncertainty then get a laser. I did.

[Railroading13]

Laser instead, I don't trust others

[cristphoto]

I noticed this several years ago when I had a Skycaddie. I could stand next to someone else with a gps and they were different more than the same. That's why I went with the laser.

[Stetson]

Does everybody here suggesting a laser ever have inconsistencies? I've used rangefinders in the past that would say 175, hit it again and says 178, then 176.

[Socrates]

That is one thing that I get too and it seems odd. Then again, I really don't pay much attention to that since it is usually a very small difference and in the big picture, I'm not that good.

[DLiver]

The calibration on one of the units is off slightly. I have a rangefinder that reads a pretty consistent 2 yard difference from most other rangefinders.

[North Butte]

Does everybody here suggesting a laser ever have inconsistencies? I've used rangefinders in the past that would say 175, hit it again and says 178, then 176.

 

The only one I've had do that for reasons other than my aiming wrong was an ancient Bushnell Medalist that had been used for over a decade. It had dirt and scratches on the lenses and sometimes would not get a reading at all so I replaced it.

 

A properly functioning laser, in my experience, is never going to change by more than plus or minus one yard when repeatedly lasering a fixed target.

[ThinkingPlus]

Does everybody here suggesting a laser ever have inconsistencies? I've used rangefinders in the past that would say 175, hit it again and says 178, then 176.

 

The only one I've had do that for reasons other than my aiming wrong was an ancient Bushnell Medalist that had been used for over a decade. It had dirt and scratches on the lenses and sometimes would not get a reading at all so I replaced it.

 

A properly functioning laser, in my experience, is never going to change by more than plus or minus one yard when repeatedly lasering a fixed target.

 

Agreed. The technology on which a laser rangefinder is based does not allow for that kind of variation unless something is broken or the device is very poorly designed. A modern middle of the road rangefinder from Bushnell, Nikon, or Leupold should provide repeatability to +/- 1 yard or less. Absolute accuracy should be good to less than a couple of yards depending upon how much care is taken performing calibration of the device.

[Patrick_O]

not a tech guy (maybe someone who is can confirm) but I've heard something along the lines of:

 

GPS is only accurate to +/- 3 yards because the US government owns the satellites and there is some sort of control on them (security reasons?) to keep it at that level, and if they removed that control it would be accurate to +/- 1 yard.

 

So I either heard that from a scientist, or a crackhead on a street corner yelling it at a stop sign. I don't really remember which one but it's crammed in my head for some reason.

sorry your second paragraph is not accurate. The accuracy is dependent upon the equipment. Watch based GPS don't have the same level of accuracy as a survey specific model such as a Trimble. Also as pointed out previously cloud cover and tree canopy can affect the results.

[Thunderfist]

These handheld GPS units are not high accuracy. Your cell phone or the handhelds that hunters use are the same. I don't think anyone would pay 20+ g's for high accaracy. It's about within one club at worse. I learned to use mine since I shake too much for a range finder.

[Hateto3Putt]

That's one of the reasons I ditched GPS years ago.

 

3 guys shooting for the same spot with a laser, you'll get 3 of the same numbers.

 

3 guys with GPS's, usually 3 different numbers. The question is, which GPS number is right...if any?

 

OP, just believe the one in your hand is spot on and make a confident swing.