Measures of Position Quality
The accuracy of GPS positions is quantified using various measures of position quality. Most GPS receivers use a limited number of these measures, and not all measures may be output by a GPS receiver. ArcPad's GPS Position Window has a drop-down list of the most common measures used. If no value has been received by ArcPad from the GPS unit, ArcPad displays N/A.
By default, the current Position Dilution of Precision (PDOP) value is shown when the GPS Position button is tapped. Dilution of precision, a measure of receiver-satellite geometry quality, uses a scale of 1 to 10. Low numbers indicate better quality. A list of the acronyms for the other measures of position quality that ArcPad can display are listed in the following table.
| Acronyms | Measure Description |
| PDOP | Position Dilution of Precision |
| DOP | Horizontal Dilution of Precision |
| VDOP | Vertical Dilution of Precision |
| TDOP | Time Dilution of Precision |
| HPE | Estimated Horizontal Position Error |
| VPE | Estimated Vertical Position Error |
| EPE | Estimated Position Error |
| SATS | Satellites used by the GPS unit to calculate the position |
| DAGE | Differential data age. This value is the age of the differential signal in seconds and the type of differential correction used. |
| DSID | Differential reference station ID. This indicates which reference station was used by the GPS unit. |
|
