Mappers heading towards Wissembourg

La Maison du Sel en Wissembourg

La Maison du Sel en Wissembourg

Finally the rainy days are over. The warm and sunny weather conditions allowed for the first mapping trip to Wissembourg by bike – the biking season finally has started.

I mapped a lot of details along the way. Some short breaks every now and then and finally a nice supper at the destination took time. Luckily »Deutsche Bahn« (a german railway company) provided public transport back home.

The location services of the N900 are pretty good, but there are also some weak points:

  • The N900 uses assisted GPS (AGPS) to get its position really quickly. If however no callular net is available, it needs ages (up to twenty minutes) to get a GPS fix. I’ve also seen such a behaviour on one of Garmin’s premium GPSrs, but only every now and then. The N900 does it each time it is outside the network of my provider. I guess the behaviour could by improved by saving an almanac to the device, but appearently the N900 doesn’t do it.
  • The first fixes the GPS subsystem delivers to the requesting application are sometimes really far (and I mean far) away from the actual position. This makes it difficult to check the trip’s length at home. I’ve never seen such a behaviour on the Garmins I used, and I consider this being a software bug.
  • Modern vehicles use screens with a vapour deposited metal layer. This hinders the GPS signals flowing into the vehicle. If the Garmin’s have a fix outside the vehicle, they are usually (but not always) capable to keep the fix after entering the car or train. The N900 today had difficulties, but as the WBT I also used today did not really do much better, I guess there were really bad GPS conditions in the train.
  • The big bug requires a second device which is more reliable for collecting tracklogs. Both Maep as well as Mapper loose their tracks in case you must hard reset the device.

Here’s how the tracklog recorded in the train looks like. Note that it should follow the rails precisely:

The device is an almost perfect gadget anyway. All I want to say is: If you reliably want to collect the tracklogs of your trips, just get an additional logger. The N900 is an exccellent general purpose device. It is not a specialized GPS receiver and logger.