Hi<br><br>I would be interested to know how you would rate external data loggers against "classical" Garmin eTrex or similar devices?<br><br>On the + side of the eTrex-like I see:<br><ul><li>More robust and usually better chip than smartphones (but probably similar to data loggers' chips)<br>
</li><li>GPS chip and map on the same device (unlike data loggers)</li><li>Relatively good battery life (with my eTrex 20 I can easily record for a full day. And if I'm somewhere without power outlets, I just take a few extra batteries)</li>
<li>OSM (or other) data can be displayed as background, which makes it much easier to see "live" what has already been mapped, what hasn't, and what can be corrected</li><li>Coupling GPS and GLONASS can significantly improve the reception in some areas</li>
</ul><p>On the - side:</p><ul><li>Real pain in the ass when it comes to log polygons (= closed ways) <br></li><li>Real pain in the ass (2) to type in waypoints names (a sheet of paper is always better for that)<br></li></ul>
<p>On the + side of the data loggers:</p><ul><li>Extremely compact</li><li>Best battery life</li><li>Cheap</li></ul><p>But on the - side:</p><ul><li>Needs a second device to visualize tracks and background data</li><li>If paired with another device through bluetooth, this will vastly reduce the batterylife (at least for the 2nd device)</li>
</ul><p>Now, have you seen significant difference in positional accuracy between such data logger and eTrex-like devices? I am so far very happy with my eTrex20 (and thus with SIRF III, despite your warning... would be interested to read why you warn against it?)</p>
<p>Cheers,</p><p>Stéphane<br></p>--<br>"Le mot progrès n'aura aucun sens tant qu'il y aura des enfants malheureux" -- Albert Einstein<br><br>"A journey does not need reasons. Before long, it proves to be reason enough in itself. One thinks that one is going to make a journey, yet soon it is the journey that makes or unmakes you." -- Nicolas Bouvier<br>
<br>Photos de voyages, photos de montagne: <a href="http://www.henriod.info/" target="_blank">http://www.henriod.info</a><span dir="ltr"><span dir="ltr" title="Appeler ce numéro de téléphone en/au(x) Tadjikistan avec Skype : +992934624662"><span> </span></span> <br>
</span><br>
<br><br><div class="gmail_quote">On Wed, Jun 13, 2012 at 2:10 AM, Boris Cornet <span dir="ltr"><<a href="mailto:borisC@osm-at.org" target="_blank">borisC@osm-at.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi!<br>
<br>
As Victor said, there are huge advantages with external devices:<br>
- power efficiency<br>
- small size (and yes, it makes a lot of difference where you carry a<br>
GPS device, cap is best, shoulder is 2nd best)<br>
- bluetooth works with any device that is bluetooth enabled on merely<br>
every OS since GPS loggers use a standard bluetooth protocol<br>
(RFComm) and send standardized data (NMEA-0183).<br>
- the chipset matters a lot: lookout for UBlox 5 (best) or MTK 2<br>
(2nd best), beware of sirf3 (!!!)<br>
- also the antenna matters: smartphones care for the phone antenna,<br>
the GPS antenna must stand back.<br>
<br>
I use the Wintec WBT 202, and I can confirm that it is far better than<br>
every smartphone I could test. The difference is not so obvious in<br>
normal conditions, but when things get rough (e.g. badly positioned<br>
satellites, high buildings, trees) the data collected by smartphones<br>
is almost unusable, while the logger still produces reasonable<br>
results.<br>
<br>
Today (Tuesday, June 12, 2012) at 23:44 Victor Ferreira noted:<br>
> Hi,<br>
> one advantage of data loggers (i use Qstarz 1000 for recording<br>
> tracks to upload to OSM) is that they are very energy eficient, and<br>
> they do not need any other device for recording the tracks. My<br>
> Qstarz easily goes on for 24h recording (or that amount of hours, in<br>
> diferent days), anf if not on, the battery lasts for weeks without<br>
> needing a recharge (very good in places without power outlets!).<br>
> But some of them also provide the possibility of being used in<br>
> realtime with bluetooth (qstarz work well with linux and windows at<br>
> least - android and iphone i do not know...).<br>
> The acuracy of all this devices are from 3meters to 10 meters,<br>
> dependin on satellite configuration and obstacules (buildings or<br>
> tree cover). After testing the data loggers in diferent positions on<br>
> the body, i found out that the best results where when i used it<br>
> hanging on my cap with a safety pin (since it is very small, no one<br>
> seems to notice the strange guy with a gps hanging from his head<br>
> hehe). It maximizes the exposure to the sky, wherethe satellites are!<br>
><br>
> Any better you should really look at professional GPS and maybe some good antenna.<br>
> Maybe you can find some second hand equipment?<br>
> Regards,<br>
> Victor Ferreira<br>
<br>
> On Tue, Jun 12, 2012 at 2:57 PM, Banick, Robert<br>
> <<a href="mailto:Robert.Banick@redcross.org">Robert.Banick@redcross.org</a>> wrote:<br>
><br>
><br>
><br>
><br>
> Hi Chuck,<br>
><br>
> <br>
><br>
> We used the Dual units while walking around a neighborhood of Lima.<br>
> It was in the southern hemisphere, obviously, but there were few<br>
> tall buildings to distort the signal. As a preliminary test we were<br>
> mostly interested in using the smartphones for visualization and<br>
> data logging, though on the fly editing is certainly a nice to have.<br>
> Our primary motive is actually to combine our evaluation<br>
> (non-geographic data collection) and GIS surveying activities in<br>
> one package using smartphones. A number of apps exist at present to<br>
> enable this, but we’re concerned that the base accuracy for most<br>
> smartphone GPS units makes them rather unreliable – hence the external units.<br>
><br>
> <br>
><br>
> We were getting 3-6 meters of accuracy with the Dual units in Lima,<br>
> readings that were confirmed by the accuracy of the data when later uploaded.<br>
><br>
> <br>
><br>
> I’d be interested in your thoughts on the other external units. We<br>
> went with the Dual units because they’re purpose built to interact<br>
> with smartphones (iPhones, unfortunately), but I’d be interested if<br>
> the data loggers you mention could do a better job.<br>
><br>
> <br>
><br>
> Cheers,<br>
><br>
> Robert<br>
><br>
> <br>
><br>
> <br>
><br>
> <br>
><br>
> Robert Banick | GIS Coordinator | International Services | Ì American Red Cross<br>
><br>
> 2025 E Street NW, Washington, DC 20006<br>
><br>
> Tel 202-303-5017 | Cell 404-964-3451 | Fax 202-303—052 | Skype robert.banick<br>
><br>
> <br>
><br>
> From: Charles Conley [mailto:<a href="mailto:cconley@immap.org">cconley@immap.org</a>]<br>
> Sent: Monday, June 11, 2012 1:52 PM<br>
> To: <a href="mailto:hot@openstreetmap.org">hot@openstreetmap.org</a><br>
> Subject: [HOT] Feedback about smartphones use for OSM field surveys<br>
<br>
><br>
> <br>
><br>
> Hello All,<br>
> I wanted to ask a couple of questions and perhaps contribute a<br>
> little to the discussion on external GPS use.<br>
><br>
> The first item I wanted to ask about is the notion of accuracy.<br>
> I'm not clear if the positional accuracy of an external bluetooth<br>
> GPS is any greater than the accuracy of a smartphone GPS. The<br>
> research I found on the net seemed to be focused more on comparing<br>
> traditional handheld GPS units to smartphones. I'm not sure if these<br>
> comparisons are valid given that most of the external bluetooth<br>
> units have more in common with GPS data loggers than they do with<br>
> handhelds. Has anyone here done any testing to determine if there<br>
> is a difference in accuracy between the data logger type of GPS and smartphone GPS?<br>
><br>
> Robert could you please add a bit more detail on the scenario that<br>
> the BT units were used? Specifically I'm interested in understanding<br>
> if they were used while walking or from a car or an aircraft. Was<br>
> the intent to allow for data editing on the fly or just using the<br>
> smartphone for visualization and data logging?<br>
><br>
> I'm asking because we have used several external GPS units similar<br>
> to the one that was mentioned. The units we used were the Qstarz<br>
> BT-Q1000eX. We did not use the BT feature of these units but rather<br>
> used them as highspeed data loggers to collect the path of<br>
> high-voltage power lines from a helicopter. We chose these<br>
> particular units because they would allow us to collect up to 10<br>
> points a second. Another interesting unit is the GiSTEQ DL500. The<br>
> DL500 doesn't have bluetooth but it does allow for logging up to 5<br>
> points a second and more interestingly is also has a 3 axis<br>
> accelerometer that would allow for determining a measure of road roughness.<br>
><br>
> Best wishes<br>
><br>
> Chuck<br>
><br>
><br>
><br>
> <br>
><br>
> ------------------------------<br>
><br>
> Message: 2<br>
> Date: Sun, 10 Jun 2012 23:48:40 +0000<br>
> From: "Banick, Robert" <<a href="mailto:Robert.Banick@redcross.org">Robert.Banick@redcross.org</a>><br>
> To: "<a href="mailto:hot@openstreetmap.org">hot@openstreetmap.org</a>" <<a href="mailto:hot@openstreetmap.org">hot@openstreetmap.org</a>><br>
> Subject: Re: [HOT] Feedbacks about smartphones use for OSM field<br>
> surveys<br>
> Message-ID: <<a href="mailto:CBFAA879.6FB6%25robert.banick@redcross.org">CBFAA879.6FB6%robert.banick@redcross.org</a>><br>
> Content-Type: text/plain; charset="iso-8859-1"<br>
><br>
> Hi everyone,<br>
><br>
> I'm happy to see this discussion taking place, as I've been<br>
> personally researching and debating this question myself for a<br>
> little while now. It's my gut feeling that as software for data<br>
> collection improves smartphones will increasingly play a<br>
> complementary role to traditional GPS devices in humanitarian fieldwork.<br>
><br>
> One contribution I might make: At the suggestion of the kind<br>
> people over at Catholic Relief Services, we're exploring linking<br>
> smartphones to high accuracy external GPS. The best model we've<br>
> encountered so far is the Dual XGPS 150<<a href="http://xgps150.dualav.com/" target="_blank">http://xgps150.dualav.com/</a>>.<br>
> We had success with some preliminary trials in Lima last fall. When<br>
> the units connected with the smartphones we received very precise<br>
> coordinates, but we encountered hiccups maintaing the Bluetooth<br>
> connection with the cheapo Androids (the model name/number escapes me) we were using.<br>
><br>
> Any thoughts, suggestions, or experiences others might have would be most appreciated.<br>
><br>
> Best,<br>
> Robert<br>
><br>
><br>
> Robert Banick | GIS Coordinator | International Services | American Red Cross<br>
><br>
><br>
><br>
><br>
><br>
><br>
><br>
> <br>
><br>
><br>
<br>
><br>
><br>
> --<br>
><br>
> Charles Conley<br>
><br>
> Chief Information Officer<br>
><br>
><br>
> 1400 16th Street, NW<br>
> Suite 210<br>
> Washington, DC 20036<br>
><br>
> Tel: <a href="tel:%2B1%20202-729-6795" value="+12027296795">+1 202-729-6795</a><br>
> Skype: minemapper<br>
> Web: <a href="http://www.immap.org" target="_blank">www.immap.org</a><br>
><br>
> <br>
><br>
<br>
<br>
><br>
><br>
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<br>
><br>
<span class="HOEnZb"><font color="#888888">--<br>
Bye Bye,<br>
Boris<br>
<br>
<br>
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