GPS AREA MEASUREMENT
Spanish

I made a square of 200 x 200 m with a steel measuring tape, checked the diagonal and angles of to corners.

So I´ve 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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