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GPS issues


CacherOfOz
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Is anyone else having MASSIVE GPS inaccuracies? I use an iPhone 5 and have been caching all week. Several times, and all day today, my GPS has been going haywire. I can stand in one spot and it reads 30'. Move two feet away and it reads 7'. Or stand still and it constantly changes direction and distance. ITS MAKING ME CRAZY!! I've only used iPhone to find geocaches and have been successful until now.

Any advice is greatly appreciated.

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I recently talked to several cachers in my area that use I phones and real GPS'rs. They all told me that they felt that I Phones are not as accurate a real stand alone GPS. I just got back into geocaching full time a few weeks ago after spending five years back college. Now before I went back to school at the young age of 58 smart phones with GPS functions were not on the market. I have been noticing that many of the caches that I have found in the past few weeks have had rotten coordinates. It is so bad that now I limit my search time for caches that are rated 2 or less to 5 minutes. At the 5 minute I move on and post a DNF. I am seeing coordinates that would have the caches inside of buildings.

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Is anyone else having MASSIVE GPS inaccuracies? I use an iPhone 5 and have been caching all week. Several times, and all day today, my GPS has been going haywire. I can stand in one spot and it reads 30'. Move two feet away and it reads 7'. Or stand still and it constantly changes direction and distance. ITS MAKING ME CRAZY!! I've only used iPhone to find geocaches and have been successful until now.

Any advice is greatly appreciated.

 

I do know that if you keep turning on and off the GPS (to save battery) it takes a long time before it finally "finds" you in the correct spot. some models need data connection to give a rough estimate of location before their GPS will sync up. I don't think this is the iphones case, but fyi anyway

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I have a smartphone and a gps unit, I have compared them during geocaching, while the gps unit leads me to about 1-2 meters to the coords, the smartphone often indicates a difference of about 8-10 meters.

So I use gps units to navigate & the smartphone with 1-2 apps for database, info and images as it offers a better reading.

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I am very impressed with the galaxy gps and it is very accurate. However for the last couple of weeks it will sometimes shoot me off by a big difference. Not sure what is up but it did update today. It will however still be right or off by 100KM. So you can definitely tell. I actually prefer to cache with my phone now that I have the Galaxy. The S3 or above works great for us.

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I have a Galaxy S3 and it uses the GLONASS system. Sometimes it's more accurate than my Oregon.

 

How do you determine the accuracy of your GPSes?

If you are lucky, you find a cache that was hidden using a surveyors GPS. There happens to be one in the metro Denver area and that is where I found out that my Venture HC was pretty darn accurate.

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If you are lucky, you find a cache that was hidden using a surveyors GPS. There happens to be one in the metro Denver area and that is where I found out that my Venture HC was pretty darn accurate.

That's cool. Did you only find it only that one time? If you've found it multiple times did your accuracy change much between visits?

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I have a Galaxy S3 and it uses the GLONASS system. Sometimes it's more accurate than my Oregon.

 

How do you determine the accuracy of your GPSes?

If you are lucky, you find a cache that was hidden using a surveyors GPS. There happens to be one in the metro Denver area and that is where I found out that my Venture HC was pretty darn accurate.

 

Aren't benchmarks (of course they are not available in all countries) typically placed using a surveyor GPS? One could try searching for a few benchmarks and see how close your GPS takes you.

 

My iPhone 4S reports accuracy and generally the best that it reports is 16 feet.

 

 

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Aren't benchmarks (of course they are not available in all countries) typically placed using a surveyor GPS? One could try searching for a few benchmarks and see how close your GPS takes you.

 

My iPhone 4S reports accuracy and generally the best that it reports is 16 feet.

 

Most benchmarks were installed before the existence of GPS. A benchmark that is listed as LOCATION ADJUSTED has been measured my a surveyor's GPS. All others are LOCATION SCALED which means that their position was determined by looking at a map.

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I use my iPhone 4 and have a reported accuracy of 16 feet (whatever that means, LOL).

 

You'll have to read the manual or the tech specs to figure that out because not all companies use the same formula to determine accuracy. In fact not all GPSrs from the same company use the same formula. On my Garmin an accuracy of 16 feet means that there is a 50% chance that the actual coordinance are with 16 feet of where the GPS currently is.

 

As you can guess playing around with that percentage can make one GPS seem more accurate than another GPS with the same accuracy.

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Is anyone else having MASSIVE GPS inaccuracies? I use an iPhone 5 and have been caching all week. Several times, and all day today, my GPS has been going haywire. I can stand in one spot and it reads 30'. Move two feet away and it reads 7'. Or stand still and it constantly changes direction and distance. ITS MAKING ME CRAZY!! I've only used iPhone to find geocaches and have been successful until now.

Any advice is greatly appreciated.

 

Ok, first off iphone number 5. Five tries and they still can't get it right. Phones are for voice to voice communications not texting. We have the technology to transmit our voices, let's use it.. Texting is like telegraphing (1800s) old technology. And certainly not for geocaching. My advice is to get a gps made for this activity, Oregon 450 for example.

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I mostly cache with an iPhone 4S but also have a Garmin eTrex 30. Whilst the accuracy of the Garmin is fantastic, I mostly use it for caching up the mountains and I don't want to drop my phone whilst up there. For most other places the phone is perfect, and rarely has problems with accuracy. My caches have been placed using the iPhone, and the coordinates are spot on. I defiantly see the benefit of having a proper GPS, but in my opinion (and experience so far) the iPhone can do the job just as well.

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I used both a Garmin etrex Vista and an iPhone 4. The iPhone is fine for most urban caches, but is not a good option for areas with tree cover or topographical features that can create "bounce" I always use the "real" GPS for placing caches as well. Bottom line, GPS uses the actual satellite, while the iPhone triangulates off of cell phone towers. While it can be accurate, it often isn't as good.

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I used both a Garmin etrex Vista and an iPhone 4. The iPhone is fine for most urban caches, but is not a good option for areas with tree cover or topographical features that can create "bounce" I always use the "real" GPS for placing caches as well. Bottom line, GPS uses the actual satellite, while the iPhone triangulates off of cell phone towers. While it can be accurate, it often isn't as good.

 

I'm sorry, but the iPhone does have built in GPS, from the 3G onwards. Whilst I agree that it's not as accurate whilst under cover of trees etc, it is still pretty good, and being able to have satalite maps can help even more.

Placing caches with an iPhone should be fine if you are sure you have got it correct. I've struggled far more with caches placed with bad coordinates than I have with my iPhone's signal.

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Many things affect GPS accuracy; satellite constellation, solar activity, atmosphere, topography, multi-path, filter settings, processing algorithms, etc. These vary on a continuous basis.

 

In general you will find that a smart phone GPSr chip will tend to be more sensitive to all those factors noted above providing generally less accuracy and stability than a standalone GPSr.

 

Placing caches with an iPhone should be fine if you are sure you have got it correct. I've struggled far more with caches placed with bad coordinates than I have with my iPhone's signal.

Signal strength of your iPhone is irrelevant. How does anyone determine that they "have got it correct"? How is it determined that struggles are due to "bad coordinates" (what ever that means)?

 

By knowingly (or unknowingly) introducing wider variences of the accuracy issues noted above (i.e. using phones instead of GPSrs), how can you attibute positioning errors to "bad coordinates"?

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I used both a Garmin etrex Vista and an iPhone 4. The iPhone is fine for most urban caches, but is not a good option for areas with tree cover or topographical features that can create "bounce" I always use the "real" GPS for placing caches as well. Bottom line, GPS uses the actual satellite, while the iPhone triangulates off of cell phone towers. While it can be accurate, it often isn't as good.

 

I'm sorry, but the iPhone does have built in GPS, from the 3G onwards. Whilst I agree that it's not as accurate whilst under cover of trees etc, it is still pretty good, and being able to have satalite maps can help even more.

Placing caches with an iPhone should be fine if you are sure you have got it correct. I've struggled far more with caches placed with bad coordinates than I have with my iPhone's signal.

http://support.apple.com/kb/HT1975

 

So how do you know if the iPhone is using GPS service vs wifi or cellular networks instead?

 

One thing that hasn't been mentioned is how you ensure correct coordinates in the first place. When I place a cache, I do three things.

1. I try to find a location with a direct connect to the sky (satellites). When possible, I place the cache in a location which a clear view of satellites. It is one of the reasons I have become known for placing caches on top of hills or mountains

2. I place the GPS (not iPhone) on top of the rock/ground/hang in tree etc. and engage the averaging feature. I try to be sure that the view to the north in particular is clear. The GPS will average coordinates over the five minutes or so I am placing the cache, placing rocks around it, etc.

3. After this is done, I will save the coordinates, then walk 50-100 feet away from the cache and back and take another set of coordinates. I will do this in 4 directions.

 

When I get home, I average the five coordinates to get the best fix. Since I live in the mountains, I have found that this is particularly important for good coordinates.

 

I stick by my first statement: the iPhone is good for urban caches, but I use a GPS for rural/mountains and for placing caches.

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