Groundspeak Forums: Getting GPS cords right. - Groundspeak Forums

Jump to content

Page 1 of 1
  • You cannot start a new topic
  • You cannot reply to this topic

Getting GPS cords right.

#1 User is offline   RacecarBarbies 

  • Tadpole
  • Group: Members
  • Posts: 2
  • Joined: 10-February 13

Posted 04 April 2013 - 11:43 AM

We are new to the Geocaching. When we go hunting we have two phones the samsung galaxy s2 and the samsung express. We use the Geocaching app. We have no trouble finding caches. We decided to hide our own cache but can not get the GPS location right. The first time we used both phones and the corrdinates matched up. When people went to find the cache they were about 17ft off of where the cache really is. So I downloaded another app to my phone we went back and tryed it again. We had the same person go find it again, she was closer but still said she was about 10ft away. Is there a better app that we should use? Shoud we invest in a cheap hand held GPS device? Thank you for any information.

#2 User is offline   alandb 

  • Premium Member
  • Group: +Premium Members
  • Posts: 191
  • Joined: 29-March 09

Posted 04 April 2013 - 12:18 PM

10' to 17' is within the expected accuracy range for consumer grade GPS receivers.

#3 User is offline   Chief301 

  • Interfering with natural selection since 1989
  • Group: +Premium Members
  • Posts: 2441
  • Joined: 07-July 10

Posted 04 April 2013 - 12:23 PM

No consumer GPS is going to put you within inches.....10 feet is not a bad margin of error. You'll probably want to invest in a "real" GPSr at some point, but in the meantime there are a couple of other things you can do to obtain the best coordinates possible:

- Don't rely on a single, momentary reading. You need to get several readings, preferably on a few different days and at different times of day, and average those readings. You can do the math yourself or see if there is some kind of waypoint averaging app for your phone (I know what's available for the iPhone, not sure about for other operating systems)

- Once you have what you believe to be a good, averaged, accurate number, try to navigate to it yourself, as if navigating to a cache. How close does it get you? Try it from a few different directions and see if it continues to bri g you right to the spot.

- Remember, as I said, that consumer grade GPS accuracy is good within a few yards, not inches. Whatever small margin of error you may have, remember that the seeker's device will have a similar amount of inaccuracy, potentially doubling the error.

If you consistently get coordinates within 10 feet or so, you're already doing better than a whole lot of folks out there. 😉

#4 User is offline   macatac1961 

  • Premium Member
  • Group: +Premium Members
  • Posts: 1456
  • Joined: 10-November 03

Posted 04 April 2013 - 01:12 PM

View PostChief301, on 04 April 2013 - 12:23 PM, said:



If you consistently get coordinates within 10 feet or so, you're already doing better than a whole lot of folks out there. 😉

I agree 10' is excellent. !7' is well within reason too. My gps does averaging when I take a waypoint. I can let it sit for a few minutes for it to get better accuracy. Or at least I haven't gotten many complaints since I discovered that feature. If your phone doesn't do the averaging, take a few waypoints with both phones and average them yourself. But getting closer than 10' is pretty tough.

#5 User is offline   RacecarBarbies 

  • Tadpole
  • Group: Members
  • Posts: 2
  • Joined: 10-February 13

Posted 05 April 2013 - 11:14 AM

Thank you for all the great information. I will go out today and see if I can pull up some more cords and average them out. Its nice to know I am not doing anything wrong, just might need to invest in a handheld GPS.

Thank you all again!

Christel

#6 User is offline   Chief301 

  • Interfering with natural selection since 1989
  • Group: +Premium Members
  • Posts: 2441
  • Joined: 07-July 10

Posted 05 April 2013 - 01:26 PM

I placed my first cache with a smartphone and have received no complaints about accuracy. It has more to do with the patience and care taken by the hider than the capabilities of the device. Smartphones a few years ago determined their location by cell tower triangulation and had no GPS chip....coordinates were notoriously inaccurate. Good enough to get you to the donut shop but not enough to place a cache. Nowadays most smartphones have real GPS and are nearly as accurate at most handheld GPS r's.

A bit of advice....don't rush out and get a cheap GPS based solely on price. If you get into this activity at all you might find yourself wishing you had saved up for something a little better. I went out and bought a Garmin Etrex Legend HCX when I first started but I soon realized I wanted something more, so within about a year I upgraded to an Oregon 550. No sense spending the money twice like I did 😶

#7 User is offline   eccentric_ 

  • Premium Member
  • Group: +Premium Members
  • Posts: 38
  • Joined: 09-June 11

Posted 09 April 2013 - 08:00 AM

Anything closer than 10' is getting too easy.
We use GPS Averaging

Don't think it's a magical app, it just averages out the noise out. You might still be 4m off from your true positions but it helps to smooth/filter out the GPS wandering.

If you want better than an external Bluetooth GPS or a real GPSr is needed.

In a few quick GPS averaging test my phone (Nexus 4) errored 3-4m off form a known bench mark (it's position was centimeters) and our Garmin GLO was less than 2m. I would like to find a few heavily wooded bench marks to see how cover changes things.

#8 User is offline   Tasilee 

  • Tadpole
  • Group: Members
  • Posts: 2
  • Joined: 16-December 12

Posted 25 April 2013 - 09:16 PM

I've been trying to find a GPS averaging app for the iPhone (for setting out caches) but having no luck so far. A few on this thread said there were some, but didn't identify them. I looked at Motion X and GPS Kit but I don't think they will average current location over time?

Thanks

#9 User is offline   Tasilee 

  • Tadpole
  • Group: Members
  • Posts: 2
  • Joined: 16-December 12

Posted 25 April 2013 - 09:25 PM

View PostTasilee, on 25 April 2013 - 09:16 PM, said:

I've been trying to find a GPS averaging app for the iPhone (for setting out caches) but having no luck so far. A few on this thread said there were some, but didn't identify them. I looked at Motion X and GPS Kit but I don't think they will average current location over time?

Thanks


I think I just found one: Perfect Mark.

Any comments?

#10 User is offline   Chief301 

  • Interfering with natural selection since 1989
  • Group: +Premium Members
  • Posts: 2441
  • Joined: 07-July 10

Posted 29 April 2013 - 04:10 AM

Perfect Mark is a good one, I haven't used it in a while since I got an actual GPS but I hid my first cache with it. Haven't received any complaints about the coordinates. 😊

#11 User is offline   Gabriel333 

  • Tadpole
  • Group: Members
  • Posts: 7
  • Joined: 12-November 10

Posted 02 May 2013 - 02:29 AM

View PostRacecarBarbies, on 04 April 2013 - 11:43 AM, said:

We are new to the Geocaching. When we go hunting we have two phones the samsung galaxy s2 and the samsung express. We use the Geocaching app. We have no trouble finding caches. We decided to hide our own cache but can not get the GPS location right. The first time we used both phones and the corrdinates matched up. When people went to find the cache they were about 17ft off of where the cache really is. So I downloaded another app to my phone we went back and tryed it again. We had the same person go find it again, she was closer but still said she was about 10ft away. Is there a better app that we should use? Shoud we invest in a cheap hand held GPS device? Thank you for any information.


I will recommend this tool for Android Devices:

Using an Android device and a tool like Geocache Placer you will be able to get a VERY precise position for your cache, and on top of that you will be able to check the position on top of Google Maps. If you think the position can be even better, you will be able to move the red marker an get the position where you think the right spot are (the green marker)!

The yellow circles is the positions used in the calculation of the "Average position" The red line shows how the "Average position" has moved over time, when adding new positions the get a more precise position.

Posted Image

#12 User is offline   Gabriel333 

  • Tadpole
  • Group: Members
  • Posts: 7
  • Joined: 12-November 10

Posted 02 May 2013 - 02:33 AM

View Posteccentric_, on 09 April 2013 - 08:00 AM, said:

Anything closer than 10' is getting too easy.
We use GPS Averaging

Don't think it's a magical app, it just averages out the noise out. You might still be 4m off from your true positions but it helps to smooth/filter out the GPS wandering.

If you want better than an external Bluetooth GPS or a real GPSr is needed.

In a few quick GPS averaging test my phone (Nexus 4) errored 3-4m off form a known bench mark (it's position was centimeters) and our Garmin GLO was less than 2m. I would like to find a few heavily wooded bench marks to see how cover changes things.


I think Geocache Placer is a better alternative, because you can check the position on Google Maps.

#13 User is offline   alandb 

  • Premium Member
  • Group: +Premium Members
  • Posts: 191
  • Joined: 29-March 09

Posted 02 May 2013 - 09:56 AM

That is a pretty cool app. That said, moving the pointer for the cache placement based on the Google map image instead of using the calculated average coordinates is no different that using the Google map to determine the coordinates in the first place. So you would be incorporating any error that exists in the Google map accuracy. I think I would stick with the calculated average coordinates.

But again, it is a cool app and one I will have to have if I ever get an android device.

#14 User is offline   eccentric_ 

  • Premium Member
  • Group: +Premium Members
  • Posts: 38
  • Joined: 09-June 11

Posted 02 May 2013 - 01:39 PM

View PostGabriel333, on 02 May 2013 - 02:33 AM, said:

I think Geocache Placer is a better alternative, because you can check the position on Google Maps.

Thanks it looks neat, I'll try it out.

And I already see my points in Google or any map. GPS Averaging is a co-app to Locus and they play well together.

I simply add a POI in Locus and "enter" the coords using GPS Averaging (sounds complicated but it's seemless) write any notes, take a picture of the hide (in Locus still), and share it with Katie (who submits our hides). And already being in Locus, I can turn on "cache radius limit" for those new POI then we can keep track of all the new hides and icon code them as necessary.

#15 User is offline   Gabriel333 

  • Tadpole
  • Group: Members
  • Posts: 7
  • Joined: 12-November 10

Posted 03 May 2013 - 04:30 AM

View Posteccentric_, on 02 May 2013 - 01:39 PM, said:

View PostGabriel333, on 02 May 2013 - 02:33 AM, said:

I think Geocache Placer is a better alternative, because you can check the position on Google Maps.

Thanks it looks neat, I'll try it out.

And I already see my points in Google or any map. GPS Averaging is a co-app to Locus and they play well together.

I simply add a POI in Locus and "enter" the coords using GPS Averaging (sounds complicated but it's seemless) write any notes, take a picture of the hide (in Locus still), and share it with Katie (who submits our hides). And already being in Locus, I can turn on "cache radius limit" for those new POI then we can keep track of all the new hides and icon code them as necessary.


This a great idea I have not thought about. I will try to add a feature to "Geocache Placer" so you can export a POI.

#16 User is offline   Heli Leo 

  • Premium Member
  • Group: +Premium Members
  • Posts: 136
  • Joined: 29-April 12

Posted 04 May 2013 - 05:03 AM

I use A:Drake on my Galaxy Slll along with GPS STATUS. At present I'm sitting in the house on a rainy day and it is showing accuracy of 13.1 feet. I often use my phone in conjunction with my Garmin 62 sc and they agree within a margin of six feet. I have placed caches using the phone and the Garmin both and had no complaints about the accuracy of the coordinates. The secret seems to be several readings on several days under different weather conditions.

#17 User is offline   JohnCNA 

  • Premium Member
  • Group: +Premium Members
  • Posts: 353
  • Joined: 27-December 07

Posted 04 May 2013 - 07:17 AM

View Posteccentric_, on 09 April 2013 - 08:00 AM, said:

If you want better than an external Bluetooth GPS or a real GPSr is needed.

With an app that averages, the biggest difference I have seen between my phone and my Garmin was .001. That's about 6 feet where I live.

What's important is to take at least two averages at least 90 minutes apart. Coming back on another day is even better.

#18 User is offline   K13 

  • Now in TechniColor!
  • Group: +Premium Members
  • Posts: 893
  • Joined: 17-April 06

Posted 04 May 2013 - 03:57 PM

View PostGabriel333, on 03 May 2013 - 04:30 AM, said:

View Posteccentric_, on 02 May 2013 - 01:39 PM, said:

View PostGabriel333, on 02 May 2013 - 02:33 AM, said:

I think Geocache Placer is a better alternative, because you can check the position on Google Maps.

Thanks it looks neat, I'll try it out.

And I already see my points in Google or any map. GPS Averaging is a co-app to Locus and they play well together.

I simply add a POI in Locus and "enter" the coords using GPS Averaging (sounds complicated but it's seemless) write any notes, take a picture of the hide (in Locus still), and share it with Katie (who submits our hides). And already being in Locus, I can turn on "cache radius limit" for those new POI then we can keep track of all the new hides and icon code them as necessary.


This a great idea I have not thought about. I will try to add a feature to "Geocache Placer" so you can export a POI.



Soooo, is this app something YOU have created?

As others have said, using the Google map to get coordinates is a wasted exercise in most areas. Just use averaged coordinates.

Share this topic:


Page 1 of 1
  • You cannot start a new topic
  • You cannot reply to this topic