GPS AREA MEASUREMENT Spanish

High accuracy in the measurement of the area

Method:
I made a square of 200 x 200 m with a steel measuring tape, checked the diagonal and angles of to corners.
So Ive got fairly correct an area of 4 ha. Then I did some measurements with GPSMeter PDA 1.67
Static navigation was turned off. The GPS antenna (HI 303 MMF) was connected with Bluetooth (BT 401)
and was fixed on a mount 2 meter overhead ground, so there were no effects disturbing recieving GPS signals from car or persons.
I am using the average function for 5 different test. WGS 84;UTM-grid.
Results:
Test number GPS Status Sats in use PDOP Times of measurement per point Area (ha) Area relative error (%) Perimeter (m) Perimeter relative error (%)
1 DGPS 7 2.5 400 3.9943 -0.14 799.51 -0.06
2 DGPS 7 - 8 2.5 10 3.9767 -0.58 797.76 -0.28
3 3D 8 2.3 20 4.0239 0.60 802.5 0.31
4 DGPS 10 0.8 10 3.9895 -0.26 799.95 -0.01
5 3D 9 0.8 10 4.0144 0.36 801.73 0.22
Expected Area (ha) 4
Expected Perimeter (m) 800
Conclusions:
In all test the relative error of measured area is less than 1%
For the test 1 where DGPS corrections was combined with very large time of measurement per point, the relative error of measured area is drastically low
Test 2 and 3 have practically the same relative error in the measured area. Test 2 have the half of the time of measurement per point than Test 3 but the DGPS corrections were used.
Test 4 and 5 was carried out the next week with the version 1.70 of GPSMeter PDA. The values 0.8 are for HDOP rather than PDOP (the HDOP filter was fixed to 2.0)
This last test shows clearly that the accuracy is better when the sats number is higher.


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