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Leaves on trees ... less new networks with GPS!

Posted: Thu Jun 08, 2006 9:52 am
by KH
The last week or so, I'm noticing new networks found without GPS location (usually one or two in a 30-40 minute stumble). The leaves on the trees? We did have rainshowers a few weeks ago, so everything is green now.

The rain kept me from wardriving a few times (as I do it on a pushbike), but now it's all sunny again.

I do monitor the GPS closely, logging the 2D/3D/none fix, and indeed it does lose fix during the ride.

Posted: Mon Jun 12, 2006 8:23 am
by mokum
you loose your 3d lock? What app are you using for stumbling?

I solved my issues with GPSD & cygwin, my come in handy for you if you use the same.

Cheers,
mokum

Posted: Tue Jun 13, 2006 5:26 am
by KH
you loose your 3d lock?
Complete loss of any lock. I found out later that the cable between laptop keyboardconnector (for power) and gps unit (a rikaline 6010-x5) is a bit worn, and what happens is that the power interrupts and the gps resets itself completely. As a temporary fix I have an extra bit of ps/2 keyboard extension cable in place which has a better connector.

I use gpsd 1.90, kismet, all under Linux.

Posted: Tue Jun 13, 2006 5:27 pm
by argh
Leaves on the trees will definitely soak up GPS signals. Anyone who has gone geocaching knows this too well! It doesn't hurt as bad as a loose connector, though.

You won't notice it as much in at higher speeds in a vehicle, but at walking (or biking) speeds you can lose lock from trees/leaves.

Posted: Fri Jun 16, 2006 5:28 pm
by i_do_dew
Leaves on the trees will definitely soak up GPS signals. Anyone who has gone geocaching knows this too well! It doesn't hurt as bad as a loose connector, though.

You won't notice it as much in at higher speeds in a vehicle, but at walking (or biking) speeds you can lose lock from trees/leaves.
My solution to this was to set the Dead Reckoning time on the GPS to its max, which on my GPS35PC is 30 seconds. This helps on all but the leafiest streets. Sure your contact points can be over 300 feet off and It does cause bunching of the APs, but you would have the approximate area mapped and later scans in the winter could shift the location to something more acurate.

Dead Reckoning is basicly that the GPS will assume that you are continuing to go the same direction/altitude/speed untill it receives new data or times out. The downside to using it for mapping is that at certain times your location could be little more than Potluck.

30 mph is 44 fps, so 30 seconds would be 1320 ft, or 1/4 mile.