Comparison of DeLorme PN40 and Garmin 62s accuracy

[janis]

I hiked Hawksbill Mountain today, going from the lower parking lot to
the summit, then to upper parking, returning to the summit, then
returning to the lower parking. Leaves along the ridge, including
Skyline Drive, are off the trees now. I followed the protocols we
worked on last week. I had a DeLorme PN40 on my right pack strap and
a Garmin GPSmap 62s on the left strap, so there should have been
minimal variation between which satellites each unit was capable of
seeing.

When I got home I downloaded both sets of tracks and waypoints, and
there was a clear winner: the Garmin 62s. The DeLorme unit had a
fairly wide difference between tracks going in opposite directions (at
times up to 25m!), but the Garmin unit's tracks were fairly tight to
each other. Interestingly, the 62s tracks were for the most part
smack in the middle of the PN40 tracks, which to me says it was
tracking more accurately. The averaged waypoints didn't show as much
variation between units.

[Thom Kaye]

That sounds consistent with what you found during our "field day".
Perhaps there is an issue with your receiver? I'm curious to know if
you were to take another PN40 alongside of it would the results be
similar. Did you happen to view the tracks collected over imagery? How
close were the two?

Thom

[Janis Stone]

Thom,

I agree it sounds consistent with our field day experience. I have not yet downloaded the imagery for the area; when I do I suspect the 62s outperformed the PN40. I'm attaching the .gpx files from both units (the file names include either PN40 or 62s) so you can take a look at them yourself. Also, it wasn't clear to me from the website how I should upload the .gpx files. I see the "submit your survey report" but it presumes you've already uploaded the files somewhere?

- Janis

[Thom Kaye]

Janis-

I'll take a look at your files here shortly. In the meantime
you'll want to upload your GPX files to the "Lucidity GPX File
Cabinet" on the www.patc-maps.net website.

Thom

>  2010-11-13_115811_Hawksbill_lowerSB_62s.gpx
> 146KViewDownload
>
>  2010-11-13_125942_Hawksbill_lowerSB_PN40.gpx
> 135KViewDownload
>
>  2010-11-13_134404_Hawksbill_upper_62s.gpx
> 275KViewDownload
>
>  2010-11-13_144333_Hawksbill_upper_PN40.gpx
> 314KViewDownload
>
>  2010-11-13_141809_Hawksbill_lowerNB_62s.gpx
> 104KViewDownload
>
>  2010-11-13_151737_Hawksbill_lowerNB_PN40.gpx
> 119KViewDownload
>
>  2010-11-13_Hawksbill_waypoint_62s_descriptions.txt
> < 1KViewDownload
>
>  2010-11-13_Hawksbill_waypoints_62s.gpx
> 13KViewDownload
>
>  2010-11-13_Hawksbill_waypoints_PN40.gpx
> 4KViewDownload

[Chris Mangold]

Thom and Janis:

   It appears you have to have a gmail account and have permissions given to you upload files. So Janis would not be able to upload the files. I don't want to give access to the general public so for those that don't have google accounts they can create one and email me to give them permissions or they can email the GPX files to patcgis@patc-maps.net.   I will update the web-site to state this.

Chris 

--
Chris Mangold
301-471-5758 (c)
301-898-7979 (h)

[Chris Mangold]

I have uploaded Janis's files to the site.

Chris

[Chris Mangold]

Janis and Thom:

    I created a File Geodatabase using the FTDS data model that Nathan gave me and upload the first of Janis's GPX files.  A few issues with my scripts to work out, hoping by the end of the week I will have a map with Janis's data.

Chris

[Richard & Sybille Stromberg]

Sorry I couldn't make your meeting.  I was up the road helping remove invasives from Blue Ridge Regional Park.

 

Are you planning to do something with GPX files that several of us already have?  Most of PATC's area is already tracked.

 

Richard

[Chris Mangold]

Sure, who should I be query for files. What other organizations in the club have been collecting data or has this mostly on individual adhoc basis?

[Richard & Sybille Stromberg]

Individuals.  I have lots of tracks saved and so does Dmitry Tundra.

[Chris Mangold]

Richard:

This is good news.  I do want to qualify and say I am trying to collect tracks as they align with PATC's trail inventory segment numbers.  I don't know if you have seen the list.   I can send it to you.   But I would like to receive the data referencing the PATC trail segments so I could manage the process better.

What are the typical protocols that you follow when collecting?   GPS, settings in terms of datum and track collection rate.  Are you collecting points every N number of seconds or based on distance.  I am assuming you are collecting with WAAS enabled.

I am almost there with the GIS data model and my import scripts if you want to send me some initial files I can load them up.

Chris

[Jim Tomlin]

Don't forget that trails can change over time, so that the data
collection date would be very important to have too. Some of these
fellows have been collecting tracks for many, many years (long before
WAAS, for that matter), and I have been on quite a few trail crews
since then, re-routing segments of trail.

They are also in the "Vigorous (i.e. incredibly fast) Hikers" hiking
group. I have seen them hike, and they are definitely not collecting
the most accurate data possible.

Jim T.

>>>>> they can email the GPX files to pat...@patc-maps.net.   I will update the

[Richard & Sybille Stromberg]

Send me the track segments.  I collect as I hike, so I could cut the hikes up into segments.

[Richard & Sybille Stromberg]

No Tuesdays for me nor Dmitri.

[Chris Mangold]

Good point Jim.   Another piece of attribute for my database.

- Chris

[Jim Tomlin]

Am I missing something, or do the trail segment signup sheets not have
the NAME of the trail in them?
I can figure it out from a map and the "From" and "To", but I'm sure
each trail does have a name (and that would make it a lot easier).

Jim T.

[Chris Mangold]

Jim:

     This is the data I received from the trails coordinator at the club, the trails were broken down into segments with their segment id's.  I can go back next week and ask if their is a different version with the trail names for all the segments.  In the mean time I can post the spreadsheets to the Web Site so you can down load them.  It might be easier to navigate the documents on your PC then on the website.

Chris  

[Chris Mangold]

Everyone:

     I must have left the trail numbers and names from the SNP Northern district.  Thom resent me the the files.   Since there is so much interest in expanding the trails that we will be collecting data for I have broken the Volunteer sign-up sheets into a Tuscarora Trail sign-up sheet and a Non - Tuscora PATC Managed Trails sign-up sheet.   Trail names and Trail IDs should be on both sheets.

Chris

Non-Tuscarora PATC Managed Trails - Volunteer Sign Up Sheet