GPS tracking – trip to the Cities
January 9, 2011 2 Comments
If I zoom into the details, I can see the coordinates match relatively well with google map, except for places that I highlighted in the inset on the bottom right. The big bend that I drove through, with an inset on the top right, seems ok but not for the other big bend. Plus, the logger recorded about 600 points, with the first few as zeros. I will have to find out why it’s recording zeros. Plus, there is one time the same coordinates were recorded 4 times. Have to find out what’s causing this, the TinyGPS library or my code. I also tried to calculate the speed and compare with the GPS speed. The results are not very accurate, sometime off by 30%.
Here is what I used as an estimate: SQRT((Lat change)^2+ (Long change)^2)/(time change)*1.11
The 1.11 accounts for the factor between 10 micro degrees and 1 meter. From the radius of the earth, 6370Km, and the 360 degrees of latitudes or longitude. I think I have made a mistake on the latitude. Will derive an accurate formula later though. But overall I’m alright with my GPS logger. I will hopefully have more time to add more display functions to it so I can read all information from the GPS, including speed, time, altitude, etc. while it records. Right now it only displays Lat/Long as it records.