Receiver Comps

[Mrzac...@aol.com]

The PN-40 is supposed to be the same receiver as the PN-60 but the 60 has expanded on board memory (SD card) and I understand we have existing tracks for this unit. I also have a DeLorme Earthmate (which I have considered to be mostly a toy or trainer) linked by BlueTooth to a Palm as data logger and external battery pack for power.

 

Do we have any field trials involving the Earthmate and is there any interest in this USB powered older model GPS? If the Earthmate is or has been proven worthy, we could field more units and field dual units for comparison and averaging.

Steve

[Chris Mangold]

Steve:

     People have been forwarding me the GPS models they have been using for data collection and I don't see anyone with a Earthmate. So I have no data for comparison. I don't know if anyone in the group has any experience.

Chris

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

[Jim Tomlin]

I use an Earthmate as an automobile/laptop PC navigator, but have
never used it on a trail. DeLorme sells them incredibly
cheaply...often they try to sell you a software package like
StreetAtlas2010 and throw in an Earthmate for a few dollars more. It
would be interesting to see how well it performs on a trail...it is so
small that it would have the advantage of being able to be attached to
the top of one's hat! But it's antenna capabilities may not be as
good, I don't know. I'm also not sure how one sets the data
collection parameters, possibly through the software on the computer
it's connected to. I'll examine it more closely next time I get a
chance.

Jim T.

[Janis Stone]

Just an FYI - the DeLorme website uses "Earthmate" as a generic designator for their consumer GPS units, including laptop-based units and PN-series devices such as the PN40.

- Janis

[Jim Tomlin]

That's right, a good point. The little units with no screens are
Earthmate LT-40 and BT-20.

http://shop.delorme.com/OA_HTML/DELibeCCtpSctDspRte.jsp?section=10091

[Mrzac...@aol.com]

I have two, maybe three of them, the one with BlueTooth I do just pin to the top of a hat (as you suggested), Palm as data logger in the shirt pocket and battery pack for the Palm and for GPS if needed for a recharge, on a belt or in a pack. Parameters set from the PC software, XMap which was the only compatible software for the early model. The USB powered Earthmate requires a PC, but you then can view the map simultaneously with logging while Palm does not and you may perform edits and add field notes using the PC. Use a small notebook PC and an Air Card for Internet access in the field, works OK but ends up being a little Rube Goldbergish arrangement with wires and batteries - maybe someone should develop a handheld GPS......

 

On the other hand, if these units are out there cheap and we need data, maybe field comparisons would be the logical first step toward "certifying" the Earthmate as a unit approved for some of the data collection needs at hand.

[Jim Tomlin]

Chris and the Maps Committee have the tough job of deciding the
ultimate requirements of the project, which would then cascade down to
help make decisions about what older data to accept, what metadata we
can and can't live without, how fast the data needs to be collected
and finalized, whether we should use fewer receiver types and take
longer, or use more receiver types and collect data faster, etc..

For examples, if the goal is merely to produce a pretty visual display
of all our trails, then we can cut lots of corners. If the goal is to
produce data that can be used to perform reasonably accurate
measurements and profiles for publications, and for rendering on a
printed detailed official PATC map, then the data collection should be
more methodical and based on a written, repeatable scientific
protocol.

When I did the GPS surveys for positioning all of the PATC cabins, I
was extremely cautious and ponderously methodical in my collection and
error checking methods. I knew that some day some poor soul was going
to be out there in a blizzard trying to find a cabin, and needed to
trust PATC to give them the most accurate coordinate possible.

Jim T.

[Mrzac...@aol.com]

Good point, needed and well taken and thanks, will have to check model numbers and avoid the generic reference to keep the various iterations straight.

Steve

 

In a message dated 11/23/2010 10:45:48 Eastern Standard Time, jfto...@gmail.com writes:

That's right, a good point.  The little units with no screens are
Earthmate LT-40 and BT-20.

http://shop.delorme.com/OA_HTML/DELibeCCtpSctDspRte.jsp?section=10091


On Tue, Nov 23, 2010 at 10:41 AM, Janis Stone <jan...@earthlink.net> wrote:
> Just an FYI - the DeLorme website uses "Earthmate" as a generic designator for their consumer GPS units, including laptop-based units and PN-series devices such as the PN40.
>
>  - Janis
> -----Original Message-----
>>From: Jim Tomlin <jfto...@gmail.com>
>>Sent: Nov 23, 2010 7:45 AM
>>To: patc-maps...@googlegroups.com
>>Subject: Re: Receiver Comps
>>

[Mrzac...@aol.com]

The cabin in the blizzard underscores the importance of both standards and metadata, which, as you point out, is the tough part of the job. As GPS technology evolves if the nature of the original data is known and understood, adjustments and extrapolations may be possible to make good use of legacy data. The Earthmate no screen models are to me an unknown accuracy or even usefulness factor; having never been considered for anything except very low budget, non precision GIS for our AT club work orders and mostly fun. But if they are cheap and the need for loaner units exists in order to obtain data from far off locales where proven collectors cannot readily go, maybe a test is in order, they could be surprising. My most recent project was developing GPS landing approaches for airports. Nearly all the data for the project is old style land survey and photogrammetric methodology converted to x,y,z coordinates to be utilized by the as of today still less precise airborne GPS to safely land. It is a matter of proper tool for the job combined with good methodology and documentation. The thought is (on airports) the technology will eventually catch up to be able to fully utilize the data.

 

Of course one can use precise data and create either pretty visuals or relative precision maps but may not extract precise data from just a pretty visual.

 

> In a message dated 11/23/2010 07:45:39 Eastern Standard Time,

[D. Tundra]

Hello,

 

A lot of people expressed their opinions about the GPS units, maps, and how the data should be collected.  I have been collecting traces for 8 years now and put them on my website www.gpshikingdc.com.  I faced a lot of the same problems in the beginning as you are facing now.  I also helped Jack Thorsen to create the map of the Doubletop Mountain which later got implemented in the PATC Map10 and Glen Palatini and Jack Thorsen to collect data for relocated Tuscarora Trail on Pennsylvania.  I read the GpsMagazine for reviews of different units http://www.gpsmagazine.com/ and reviews on various sites that sell them.  So here is what I think the questions are and my answers to them.

 

1) What consumer GPS is the best and why?  Is it important to get that best GPS and why?

A GPS receiver as any receiver is characterized by the receiving antenna and data amplification and processing electronics.  There are 2 types of antennas - a patch (basically a piece of wire) or a quadrifilar helix.  The later gives better reception.  The receiver electronics is best if it is made by a company called Sirf.  Most modern units have Sirf chips in them, but only a few have a good antenna.  These units are all Garmin:

GPSMAP® 78s 

GPSMAP® 78sc

GPSMAP® 60Cx - older model

GPSMAP® 60CSx - older model

GPSMAP® 62s

GPSMAP® 62st

+ GPSMap 76Cx or CSx, which is what I have and what is apparently out of production.  The 76 and 78 models are also waterproof and floatable as opposed to be water-resistant.  All models above have a capability to attach an external antenna which will further improve the reception.  My favorite external antenna is http://www.gilsson.com/, since it's good and inexpensive.  I don't use it now since the receiver is good enough, but used it all the time in the preSirf days.

 

We want to have the best receiver possible because the mediocre receiver will loose reception in the mountains, under heavy tree canopy, in the river canyons.  Any receiver will work just fine on water and on an open street, where there is an unobstructed view of the sky and thus the satellites.  Delorme, Magellan, and majority Garmin models are those mediocre receivers...

 

2)  Who's and what data do we want to allow to the database?

I would allow any and all data as long as it is not hand written in mapping software, but taken in the field.  We want to have all tails covered in our database as soon as possible even if the data is outdated.  We can always improve on it later on.  Just like with Wikipedia or Amazon.com we can have reviewers comment on it and delete the inappropriate content.

 

3) What are the objectives of this database?

I want to make a very important point here.  This database is a collection of hike traces, NOT a trail map.  PATC cartographers will take these hike traces and convert them into the trail layer for the GIS database to be published on a map.  For example, John Doe submitted the Old Rag hike trace to the database.  Other people submit other traces.  A cartographer takes these traces, loads them into a program like ARCGIS, edits them and creates a layer with all the trails of the Central Section of the Shenandoah Nat. Park  for the PATC Map 10.  This cartographer or a third person makes sure that the traces are current and correct.  He adds the layers of elevation contour lines, streets, streams and mountains, etc. and publishes the map.  The objective of the database should not only be to provide data for the cartographers for creating printed maps but also for hikers to pick up a trace, downloaded it and hike it.

 

4)  How would I group this database?

Pretty much by State and then the PATC Map grouping.  E.g.  All the traces of the Central SNP will be in VA -> Map 10 group.  Traces that are not part of the PATC maps can be grouped by State -> County.  If the trace falls into 2 or more groups, it should be put in the one where it's length is the longest.  E.g. Harpers Ferry hike should be in MD if it started at Weverton Cliffs.  It should be in WV if it was only in the Harpers Ferry.  It should be in VA if it was mainly in Loudoun Heights.  Blockhouse Point trace should be in Maryland -> Montgomery Co., since it's not on any PATC Map.

 

5)  What tags should be associated with each trace?

As many as possible, and whatever can be filled, should be filled.  There should be Yes/No, Option and Fill In fields associated with the trace when it is submitted, but only a few if any fields should be required.  Here are some of the fields that come to my mind:

*Date of the trip

*Hike/Backpack

*Loop/Out-n-Back/Tennis Racket Shape

*Names of the trails.  Are any of these trails outdated?

*Bushwhack/Always on Trails.  If bushwhack, how many bushwhacking miles.

*Waterfalls (yes/no) and name if yes

*Overlooks (yes/no) and name if yes

*Special features (e.g. Columnar Junction at Compton Peak - an interesting geological feature)

*Parking Lot coordinates and information about it.

*Comment Section: I liked this and that, I recommend this trip for this and that.

*Warning Section: hunting season, slippery rocks, wadings, unclear blazes.

*Contact information for the author, not to be published, but in case cartographer needs additional details.

 

6) An elevation profile and statistics should be automatically created and posted next to the trace.  Statistics should include total elevation gain and loss,  max and min height at the very minimum.

 

7) There should be a way for people with multiple traces to submit them in a lump, not individually.  I have 100s of traces, and so do some other people I know.  We won't submit them one-by-one.

 

8) Not all the traces are equal.  There are "Special Hikes" to "Special" places.  For each section, it would be a good idea to have traces with lots of details and good description, which represent these special hikes. 

 

9)  Different people use different software to work with the traces.  Most people I know and myself use Topo! Mid Atlantic and Pennsylvania by National Geographic.  Other people use Delorme's or Garmin's software, not to mention 3d party programs including Google Earth and GPSTrackmaker.  This database should allow only the *.gpx format.  I would put a link to the free utility gpsbabel - www.gpsbabel.org that allows to convert from one format to another and from any format to the *.gpx.  By the way, all programs mentioned above allow to import *.gpx directly into them.

 

10) I wouldn't restrict the database to the PATC maintenance region.  If a person went to California or France and had a great trip, let's post it in the NonPATC section of the database anyway.

 

If you have any questions about any of the above, please let me know.

Dimitri Tundra

 

[Richard & Sybille Stromberg]

I yield to Dmitri on details about GPS performance.  I have been delighted with my Garmin 60Csx and interfacing it with TOPO to up- and download tracks, waypoints and routes and producing maps.  Maps, profiles and pictures from most of my hikes can be seen at http://risy.smugmug.com/Hikes.  I have .gpx and .tpo files for most of them.

 

For examples of what we could/should do, I suggest looking at

 

- Hiking Arizona http://hikearizona.com/dex2/index.php difficult to navigate, and you may have to register to look at it, but full of info, maps, pictures, hike descriptions, etc.

 

- Backpacker Magazine http://www.backpacker.com/destinations/ again you have to register

 

- MidAtlanticHikes.com example at http://midatlantichikes.com/buckhollow.htm

 

- Hiking Upward example at http://www.hikingupward.com/SNP/OldRag/

 

Richard Stromberg