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GPSr, which one to get?


KC9PDY
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This is my first post here. I am new to Waymarking, and have been using an app on my iPhone, to get the co-ordinates I need.

 

Is it worthwhile getting a GPS receiver (a proper one) or am I better off staying with the iPhone app?

 

Next question would be, which one? A lot of them seem to be made for in car use, with driving directions.

 

Any pointers, hints or tips here would be appreciated ...

 

Colin (KC9PDY)

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Hello there kc9pdy.

I don't want you to feel ignored, but I'm not the most qualified person to answer your question so I hesitated in responding. I will answer your questions the best I can, based on my knowledge and experience.

 

I do not use a smartphone gps/app. I use a handheld gps unit. However, as long as your phone/app gets you very accurate coordinates, it should suffice for Waymarking. Car gps units CAN be sufficient for Waymarking, with the possible exception of waymarked items that need REALLY accurate coordinates, such as headstones.

 

I recently purchased a replacement handheld gps unit for $125 and it is absolutely wonderful for Waymarking: durable, accurate, and easy to use.

 

Hopefully soon someone else will put in their two cents and give you specific advice on your iphone/app.

 

Welcome to Waymarking.

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Thanks for the reply Max, what I was trying to get help with was figuring out, whether, a handheld GPS would be worth getting, or would I be better to stick with the free iPhone app, for now.

 

Also, if I would be better off with a real GPS unit, which one or ones are recommended.

 

I see you need to buy maps to go in the GPS unit, if I understand this correctly?

 

Colin (KC9PDY)

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If I were doing it all again, I wouldn't purchase a GPS unit. For Waymarking there is really no value in the little extra precision you might get from a handheld. stand alone unit. If all you are doing is posting waymarks, stick with your iPhone app.

 

For geocaching, I find it easier using my Garmin Oregon. It has more precise coordinates, updates more frequently. Given that, I still don't see the value of paying 300+ for the unit. When using the Android app, I need a little more geosense, but otherwise it does good enough.

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If I were doing it all again, I wouldn't purchase a GPS unit. For Waymarking there is really no value in the little extra precision you might get from a handheld. stand alone unit. If all you are doing is posting waymarks, stick with your iPhone app.

 

For geocaching, I find it easier using my Garmin Oregon. It has more precise coordinates, updates more frequently. Given that, I still don't see the value of paying 300+ for the unit. When using the Android app, I need a little more geosense, but otherwise it does good enough.

 

Thanks GT.US, I find that Waymarking fits in with my other hobbies. I have not tried Geocaching, as yet. But your feedback on the usefulness of the iphone app is what I wanted to know, I suppose.

 

Thanks again :)

Colin (KC9PDY)

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Hi Colin,

With your ID looking enormously like a ham callsign, have you ventured down the path of APRS at all? I am yet to go in that direction myself, but have been looking at http://www.byonics.com/ ? Obviously you won't have direct access to maps, but it might give a leg in, because as gt.us suggested, accuracy is often not particularly demanded. I have also seen very cheap (<$40) "keyring" GPSr's on ebay.

cheers Vaughan (vk2kbi)

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My 2c worth.

 

I use the iphone app "Theodolite". Using this app you can take a photo of the waymark with the lat and long, plus lots of other geo information, superimposed on the image. I can then put all of my photos, from my camera and the latlon iphone pics, into one folder or album. In this way the timestamped iphone geo coord images are associated with the timestamped waymark photos. This makes it easy to match latlon with the waymark.

 

I also take a google maps screen shot of the region from time to time and add this to my photo work flow. This helps in built up areas, also as a general check that all is ok.

 

This would be my recommendation.

 

The Buddha in Laos. Images attached.

 

DSC08258.jpg

 

IMG_7559.jpg

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Hi Colin,

With your ID looking enormously like a ham callsign, have you ventured down the path of APRS at all? I am yet to go in that direction myself, but have been looking at http://www.byonics.com/ ? Obviously you won't have direct access to maps, but it might give a leg in, because as gt.us suggested, accuracy is often not particularly demanded. I have also seen very cheap (<$40) "keyring" GPSr's on ebay.

cheers Vaughan (vk2kbi)

Hi Vaughan, yes indeed that is a ham callsign. I have not ventured into APRS, as yet, but will check out the link you suggested. Maybe, another look on eBay is called for too. :(

 

Cheers, Colin (KC9PDY)

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My 2c worth.

 

I use the iphone app "Theodolite". Using this app you can take a photo of the waymark with the lat and long, plus lots of other geo information, superimposed on the image. I can then put all of my photos, from my camera and the latlon iphone pics, into one folder or album. In this way the timestamped iphone geo coord images are associated with the timestamped waymark photos. This makes it easy to match latlon with the waymark.

 

I also take a google maps screen shot of the region from time to time and add this to my photo work flow. This helps in built up areas, also as a general check that all is ok.

 

This would be my recommendation.

 

The Buddha in Laos. Images attached.

 

DSC08258.jpg

 

IMG_7559.jpg

 

Hi Ianatlarge, thanks for your input. I checked out Theodolite in the app store. It looks like it does a lot more than just give the lat-lon co-ordinates. One point though, that gives the lat-lon for where the photo is taken from, not of the object itself? :)

 

Colin (KC9PDY)

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KC, you are correct. The app takes the latlon from the position of the iphone, however, I usually get close enough to the waymark to render the difference in position irrelevant, or, when I cannot do this, I adjust the latlon to reflect the separation between the iphone and the new waymark. The good thing about having the latlon and an actual image of the object in one photo is that it is easy to make these assessments. Something that you cannot easily do with just the latlon numbers.

 

And, yes, the app does far more than simply tell you the latlon. It can judge distance, height, angle, show size, and take out the laundry. I admit I don't use 10% of what it can do.

Edited by Ianatlarge
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Hi, Carl. Since Geocaching came first for me (not by much, though) I already had my GPSr. I used Magellans for quite awhile before getting a Garmin Colorado 300. It worked great for Waymarking and fine for Geocaching, except it could not handle multi-caches, a puzzling omission for a unit with a lot of Geocaching-specific features such as supporting Where-I-Go. Recently it went bottom-up because it was no longer being recognized by any computer. Hence, I was unable to load coordinates, individually or as pocket queries, and I couldn't get data off of the unit. Fortunately, I had only a few waymarks that I hadn't downloaded, and I can copy them manually. So, I have a Garmin Oregon on order that should arrive in a few days. I hope it does Waymarks okay.

 

I've not used smart phone apps much. My main issue with them, and with cameras that also record coordinates, are (1) accuracy (2) as mentioned, coordinates from where the photo is taken and not the site/object itself. I know that opinions differ, but I feel both of these are important considerations. How accurate are smart phone apps? Probably close enough. Some people use them for locating Geocaches, and seem to do fine, so that seems to be enough accuracy.

 

The bigger problem is that of coordinate placement. With some exceptions, coordinates should be at the actual site or object of the waymark not from some viewpoint. I've declined waymarks for just this reason. This problem is easily overcome, however, simply by walking to the building entrance, to the object, or whatever and taking a photo that serves as the one for the coordinates for the waymark (even if the photo itself isn't used), just as one would do if recording the coordinates with a dedicated GPSr.

 

I will certainly take a look at the app Ian illustrated. It would be very useful to me in a number of ways. Certainly as a backup to matching photos and coordinates, as well as its other functions.

 

By the way, many of the active waymarkers here in Korea are also amateur radio operators. Technology likes technology, I guess.

I've not bothered to get my reciprocal ticket here, or even get on the air with the bad propagation. All in good time.

 

Larry (KE1HZ, ex-HH2WL)

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When I first started Waymarking I performed a few experiments to determine the accuracy of the gps on my iphone, and did a little research to see what others had to say on the same subject. Long story short, I found that an iphone app is accurate to 10m-20m, usually closer to 10m than the 20m.

 

To make this determination I took successive spots of one location over several days, I also took repeated spots of a known location, and I tried several different apps. In light of this discussion thread I thought I should try the experiment again. Which I just did.

 

Again, the iphone (iphone 4) is accurate to within 10m plus. I have noticed that the assisted gps greatly speeds the acquisition of an accurate position. When Waymarking in countries where I do not have a sim card in the phone it can take, at first, up to several minutes for the coordinates to settle down to one figure.

 

What I have found is that local conditions: buildings, trees, the weather, affect the accuracy of the gps. (Though, in an electrical storm one really should not walk around waving a gps in the air).

 

In conclusion, an accuracy to 10m plus (~ 0.0001 degree) is readily attainable, different iphone apps give the same result, and that a smartphone (at least an iphone) is as accurate as a dedicated gps device.

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When I first started Waymarking I performed a few experiments to determine the accuracy of the gps on my iphone, and did a little research to see what others had to say on the same subject. Long story short, I found that an iphone app is accurate to 10m-20m, usually closer to 10m than the 20m.

 

To make this determination I took successive spots of one location over several days, I also took repeated spots of a known location, and I tried several different apps. In light of this discussion thread I thought I should try the experiment again. Which I just did.

 

Again, the iphone (iphone 4) is accurate to within 10m plus. I have noticed that the assisted gps greatly speeds the acquisition of an accurate position. When Waymarking in countries where I do not have a sim card in the phone it can take, at first, up to several minutes for the coordinates to settle down to one figure.

 

What I have found is that local conditions: buildings, trees, the weather, affect the accuracy of the gps. (Though, in an electrical storm one really should not walk around waving a gps in the air).

 

In conclusion, an accuracy to 10m plus (~ 0.0001 degree) is readily attainable, different iphone apps give the same result, and that a smartphone (at least an iphone) is as accurate as a dedicated gps device.

 

Hi Ian,

Thanks for your time and effort in obtaining your answer. That is very interesting, that the iphone is really pretty good at obtaining gps coordinates ... I think I will stick with the iphone, at least for now. Maybe later, get a dedicated gpsr.

 

Colin (KC9PDY)

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Hi, Carl. Since Geocaching came first for me (not by much, though) I already had my GPSr. I used Magellans for quite awhile before getting a Garmin Colorado 300. It worked great for Waymarking and fine for Geocaching, except it could not handle multi-caches, a puzzling omission for a unit with a lot of Geocaching-specific features such as supporting Where-I-Go. Recently it went bottom-up because it was no longer being recognized by any computer. Hence, I was unable to load coordinates, individually or as pocket queries, and I couldn't get data off of the unit. Fortunately, I had only a few waymarks that I hadn't downloaded, and I can copy them manually. So, I have a Garmin Oregon on order that should arrive in a few days. I hope it does Waymarks okay.

 

I've not used smart phone apps much. My main issue with them, and with cameras that also record coordinates, are (1) accuracy (2) as mentioned, coordinates from where the photo is taken and not the site/object itself. I know that opinions differ, but I feel both of these are important considerations. How accurate are smart phone apps? Probably close enough. Some people use them for locating Geocaches, and seem to do fine, so that seems to be enough accuracy.

 

The bigger problem is that of coordinate placement. With some exceptions, coordinates should be at the actual site or object of the waymark not from some viewpoint. I've declined waymarks for just this reason. This problem is easily overcome, however, simply by walking to the building entrance, to the object, or whatever and taking a photo that serves as the one for the coordinates for the waymark (even if the photo itself isn't used), just as one would do if recording the coordinates with a dedicated GPSr.

 

I will certainly take a look at the app Ian illustrated. It would be very useful to me in a number of ways. Certainly as a backup to matching photos and coordinates, as well as its other functions.

 

By the way, many of the active waymarkers here in Korea are also amateur radio operators. Technology likes technology, I guess.

I've not bothered to get my reciprocal ticket here, or even get on the air with the bad propagation. All in good time.

 

Larry (KE1HZ, ex-HH2WL)

 

Hi Larry,

Maybe, it is the natural inquisitiveness that I, as a Radio Ham have, and maybe Waymarking also feeds this, a need to understand how and why things are where they are, and how they work...

 

I am not sure i phrased that very well, but I hope you know what I mean?

 

Colin (KC9PDY)

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The GPS part of iPhones are good enough, but most applications don't tell you what method of location determination is currently used. Triangulation based on cell towers and WLAN stations are also used. The other two can be even more accurate in city centers but have poor results in the countryside. The record I have personally noticed was an offset of over 500 km; I guess a nearby company building was using WLAN equipment that was in the database still at a former location.

 

You should be outdoors and wait about two minutes, when the location does not move anymore then it's usually correct.

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If anyone has experience using a Garmin Oregon for Waymarking, I'd love to hear from you. I recently got one to replace a Colorado that stopped working, and I'm having problems downloading the comments and date into GSAK.

 

I use an Oregon but stopped using GSAK a couple years ago due to changes in policy changes at my company for software installations. (I use my company laptop most of the time as I got tired of traveling with two :-) ). I know that both fields are populated as I open the gpx file that Oregon creates in Excel and use both fields. You may want to check on the GSAK forums to see if there is any information there, they are pretty informative and helpful there. Check in GSAK that you have changed GPS setup.

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The GPS part of iPhones are good enough, but most applications don't tell you what method of location determination is currently used. Triangulation based on cell towers and WLAN stations are also used. The other two can be even more accurate in city centers but have poor results in the countryside. The record I have personally noticed was an offset of over 500 km; I guess a nearby company building was using WLAN equipment that was in the database still at a former location.

 

You should be outdoors and wait about two minutes, when the location does not move anymore then it's usually correct.

 

Fi — you are correct about phones not indicting which means of signal location they are relying on. It would be good if one app did this, but so far no. The trick is, as you say, when you first move to a new location, or first use the gps app that day, to let the phone (or a gps) have a few minutes to acquire a good set of satellite signals before Waymarking. I usually back this up by taking a google map screen shot of the local area, with my location marked on the map.

 

When in Waymarking mode I walk around with my phone and camera on a neck lanyard. This means I can keep the gps app running continually, and have all my gear at hand, and look like a complete geek. I also continually gaze up and around at buildings looking for date stones, and mutter to myself about category requirements. This has the added benefit that people back away from me and walk quickly away.

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If anyone has experience using a Garmin Oregon for Waymarking, I'd love to hear from you. I recently got one to replace a Colorado that stopped working, and I'm having problems downloading the comments and date into GSAK.

 

I've used a Garmin Colorado and Oregon. I'm using the Garmin BaseCamp software to extract waypoint data from the GPSr. Connect your GPSr via USB cable and click the "Receive" button to bring all the GPSr data into the BaseCamp database.This program manages your database of waypoints and presents them geographically on a map, to help you find them by locality. You can scroll the map around, zooming in and out to focus on an area of waypoints. BaseCamp allows you to make lists and smart lists, which are collections of your waypoints, similar to iTunes playlists and smart playlists. Finally, copy and paste of the coordinate data into your waymarks eliminates transcribing errors. I give it a thumbs up for a free application.

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When I first started Waymarking I performed a few experiments to determine the accuracy of the gps on my iphone, and did a little research to see what others had to say on the same subject. Long story short, I found that an iphone app is accurate to 10m-20m, usually closer to 10m than the 20m.

 

I often take pictures of signs with my iPhone, because I'm usually right above or very close to the sign. I use this geotagged photo for comparison with my GPSr acquired data and to complement pictures taken with my point-n-shoot camera, which doesn't do geotagging.

 

I've written AppleScripts to acquire the geotagged data from the photo, which is stored in decimal degrees, and convert that form into the degrees & minutes form used in Waymarking/Geocaching. These conversionsalwaysgive me a value with only two significant decimal digits. That means I get a value like N37 dd.dd0, W121 dd.dd0, where the third decimal digit is always a zero. In my experience, I think that third digit amounts to about 6 feet of accuracy for every .001, so without that third digit, I feel like the accuracy range is about 60 feet. That's similar to your finding. I don't think 60 feet is very good, particularly for a geocache or small waymarks. In comparison, my GPSr reads out a full 3 significant decimal digits of accuracy.

 

While we're on this topic of accuracy, let me make a recommendation of using the Waypoint Averaging function of your GPSr, if it has it. This is a standard feature on my Garmin Oregon and I think other units support this concept as well. I've moved the function button to the first screen. I collect almost all of my coordinates using waypoint averaging. It may take a minute or two to complete, but the accuracy is extremely high and worth it. When I arrive at my waymark, I set my GPSr down near the object and start the waypoint averaging feature, while I'm taking my photos. After a couple of minutes of photos, the GPSr has captured coordinates that the unit believes to be 100% accurate. I then use the Waypoint Manager of the GPSr to edit and name that waypoint.

 

During waypoint averaging, the GPSr takes coordinate measurements over a period of time, until it has honed in all satellite signals, and averaged the results until the coordinates are believed 100% accurate. You can stop the process early and the averaging may not have as high a guarantee. The only time I use Mark Waypoint is when I can see the satellite accuracy is already within 10-15 feet, or the place I'm Waymarking is more like a park, playground or basketball court where 10-15 feet probably close enough. Sculptures, headstones, clocks, signs and other small objects get waypoint averaged, to get the most accurate coordinates possible.

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DougK, you got me there. No iphone app that I am aware of does gps averaging. This is a surprising omission, as averaging could be easily implemented in software. (I just had a quick look at the Apple developers forum. Possibly the iphone api does not allow this? Not sure.) I do recall gps averaging — back in the 20th (at least I think I remember the 20th), accuracies to 2-3 metres were attainable, even better if you were prepared to spend hours waiting for the result. (I used to do Luna occultation observations. Astronomers are obsessive about decimal points!)

 

My finding is that your iphone app will give an accuracy of 10m or less, when used correctly. That is to say, give the app a minute or two to settle down, and hope for unobstructed skies. This is a 30' diameter or less. Usually less, based upon my experiments. The "MotionX GPS" app (which modestly claims to be "MOST ACCURATE IPHONE GPS!—in caps with an exclamation!!) gives an accuracy reading. This settles down to 3, 4 or 5 metres after a minute or two, 10-15'.

 

It comes down to the required level of accuracy. As you say, with large waymarks ~10m is not a problem. My favourite waymarks are large: train & bus stations, temples, and dated / neon buildings. I invariably compare my gps spot to google maps (lets not switch to Apple maps), and, when possible, I add a physical address to a waymark. I try and use the entire mix to gain the final position.

 

I feel that even relatively small waymarks: fountains, sculpture/statues, are sufficiently large and distinctive that an accuracy of 5-10m is reasonable. The problem I have with accuracy is not the gps, but with the local environment, trees and such that obscure the signal.

 

The only category that I find heavily demanding of gps accuracy is the one that involves searching for and finding entirely virtual spots on the Earth's surface, indicated only by the decimal based juxtaposition of terrestrial, angular lines of demarcation. To reach the desired decimal accuracy requires that one walk around in circles, draw lines in the sand, mutter under one's breath, and generally looking like a complete idiot to anyone passing by.

 

So, what I am getting at is that, I believe that the fourth decimal place in a decimal degree is sufficient, and that for a large part of the time, all we can realistically hope for.

Edited by Ianatlarge
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I did some searching and found a bundle of articles about gps accuracies, but this seems the most relevant.

 

http://academics.skidmore.edu/blogs/onlocation/2012/03/smartphone_accuracy/

 

They found that an iphone is accurate to ~8m, while a Garmin gps was accurate to ~3m. A substantial difference, however, this ~8m is effectively what I found for my iphone.

 

What is curious is that the two, identical model gps devices gave different accuracies. One was ~twice as accurate as the other (1.7m v 2.9m), but even here the accuracy of each varied widely. One on measurement (#3) the "accurate" gps gave a less accurate measure than did its less accurate associate.

 

I also gather, from reading between the lines, is that these chaps did not pause for long at each gps spot. My impression is that the iphone requires a longer time to accurately measure its position.

 

So, bottom line, is 8-10m / 25-30', sufficiently accurate for Waymarking?

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Hi Colin,

With your ID looking enormously like a ham callsign, have you ventured down the path of APRS at all? I am yet to go in that direction myself, but have been looking at http://www.byonics.com/ ? Obviously you won't have direct access to maps, but it might give a leg in, because as gt.us suggested, accuracy is often not particularly demanded. I have also seen very cheap (<$40) "keyring" GPSr's on ebay.

cheers Vaughan (vk2kbi)

Hi Vaughan, yes indeed that is a ham callsign. I have not ventured into APRS, as yet, but will check out the link you suggested. Maybe, another look on eBay is called for too. :(

 

Cheers, Colin (KC9PDY)

 

Greetings from Watertown, SD.

 

I do both Waymarking and geocaching. I have several GPSr, one of which is a Garmin Colorado. I like it. I also use Garmin Etrax for marking waymarks. It is easier to use for that application than a Colorado.

 

Also, I am a novice Hamster. KD0HWL

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DougK, you got me there. No iphone app that I am aware of does gps averaging.

 

There's an app for that, it's called Perfect Mark. It's free. There may be others but this is the one I used to place my first Geocache, before I got a GPSr. Haven't received any complaints about the accuracy of my coordinates.

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