[GPS for EarthMate] GemLocal - moving maps for Pocket PC

February 2010  –  I made some updates to GemLocal to cater for syntax changes in the URLs to the various map providers. Please download version 1.2.

[Gem for Windows]

A little history

Long time ago I developed GemQuest (today's incarnation is GemGlobal), a program to download maps from the internet and then use them while on the road. By connecting a GPS, originally a Delorme EarthMate but later also other types, you could get a moving map system for in-vehicle navigation.

Many people, myself included, discovered that mounting a complete laptop in your car is not the most convenient form factor. A smaller unit would be much more practical. That resulted in PocketGem, a scaled down version, running on Windows CE, aka Pocket PC.

The platform had many limitations, like two levels of directory tree and it was always tough for the program to find its configuration files. Today, the devices are much more powerful and closer to what a Windows desktop can do. The smart-phone I use for example (a HTC Artemis) uses GPRS to go on-line on the Internet and it has a built-in GPS unit. And of course, it's easy to add a tiny memory card with a huge capacity for storing all your map files, which makes life much easier.

When it comes to GPS devices, the protocol has by now standardized on NMEA. For communication you have the choice between BlueTooth or built-in GPS units. There are still a lot of USB devices, but those aren't a very good fit with your typical PDA or smartphone.

GemLocal program is an intermediate step. The original PocketGem was a PocketPC 2000 program. I'm working on a full-fledged Windows Mobile 5 based program, which will also be better suited for smartphones. This current GemLocal version is based on PPC2003, so it needs a stylus to operate the menus, but for the rest it runs fine on WM5 based devices. Finally all PDAs and phones now seem to be using the ARM processor. Which simplifies life a lot from a standardization perspective.


Region Map Aerial Photo

[register GemLocal]

Get the goodies

This is what everybody is always looking for: Don't RTFM, but just grab the stuff and start playing :-). OK, click the button on the left, which leads you to a page with a similar button where you can download a CAB file. Use ActiveSync to copy this file to some temporary directory on your PDA / phone. On the phone, double-click it, say yes, yes and yes :-) and the program has installed itself.

The first time it runs, it will install a couple of setup files. Because, by default, it will not go on-line to the Internet, nothing much will happen. So, either do a File -> Online and wait for maps to be downloaded, or exit the program and copy over some map files from your desktop. The default directory they should go in is "\My Documents\GemLocal\Maps", but you can change that in gem_ini.txt if you want to store the maps on a memory card.

Setting up the communcation with the GPS can be damn easy, or a nightmare that takes days. I will try to write more about that lateron, but for starters here is post to the net on that topic.

Use the GPS Monitor feature to see what is happening with the GPS communication. Maybe you just have to wait for your GPS to find its satellites.

Maps, maps and maps

This has become much easier since the days of PocketGem. GemLocal is solely using the maps of VirtualEarth (aka maps.local.live). And those are simple 256 x 256 tiles, both as maps as well as satellite images. The directory tree structure GemGlobal uses for storing its map and satellite files, is the same as used by GemGlobal.

Street Map Debug Info GemLocal Options Satellite Monitoring


The little details

Let's go through the menu of GemLocal, item by item.

  • Gps -> Online - In case your PDA has a (GPRS) internet connection, you can enable it here (default is off !!).
  • Gps -> Offline - Switch to offline to disable downloading maps from the Internet.
  • Gps -> Connect - Try to make a connection with your GPS unit.
  • Gps -> Disconnect - Break the link with the GPS.
  • Gps -> Exit - Don't you dare :-) .... but seriously, this is different from clicking the X in the top-right, in that it "really" stops the program.

  • Options -> Aerial Photo - When selected, you will get a satellite photo instead of the standard map.
  • Options -> Auto Pan - This mode (default selected) will try to "pan" the displayed map, when the GPS unit is moved. You can select Auto Pan also by clicking the top left toolbar button.
  • Options -> Track - In this mode (default off) the old GPS markers will not be deleted, to allow you to follow your tracks.
  • Options -> Monitor - To help you get your communication going, but also to see more detailed satellite data. When the "dbug=#" in gem_ini.txt parameter is set to 1, 2 or 3, GemLocal will display more detailed information from your GPS.

  • Help -> Support - As Nike says: Just Do It....
  • Help -> About - Shows the usual copyright message.

Features that are more static in nature are set using the gem_ini.txt configuration file:

  • With "site=GoogleMaps" or "=VirtualEarth" you can select your online mapping source.
  • The parameter "maps=" let you adjust where your files are stored. Default is "\My Documents\Pocket Gem".
  • The initial zoom-factor when starting Gem is controlled by adding a line "zoom=#" to gem_ini.txt, where n is a value from 0 to 4.
  • With "port=COM1" you can control which serial port to use. Only specify here baudrate, etc., if all else fails.
  • The "type=NMEA" parameter is now deprecated, because only NMEA is supported.
  • With the option "hair=1", a cross-hair will be added to mark the current position. You can choose a line-thickness between 0 and 9.
  • With the option "file=filename", Gem will track positions to the specified logfile. In the menu, you will have to enable tracking as well. And it is your responsibility to empty this file from time to time.
  • With "base=host.domain:port" GemLocal will start sending its position to a basestation running Gem (this feature wasn't tested for a while).
  • To set the level of detail used for the Monitor window, set the "dbug=#" parameter to 1, 2 or 3. Disable with "Dbug=0".

The GemLocal program will use "gem_pos.txt" to store the lat/long when it gets a first fix after starting the program. The next time the program starts, these coordinates are used to load the first map.


Support World Map


The menu option "Support" has always been my little joke with a reverse twist. It is not there to help you, but just to remind you of your side of the deal.

I got many requests to develop this version of GEM for the PocketPC. To develop this program I had to invest real hard dollars in tools, books, etc. So I think it more than fair that GemLocal is shareware that will annoy you if you don't pay your fair share.

As is the usual deal with shareware, try it out, see if you like it and if so, surf on to www.schaik.com/gps/gemlocal/register to get your license key.

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  Willem van Schaik, Calgary, February 2010     http://www.schaik.com/wwwillem.html