Operation Manual

18 User Manual

racy is obtainable when the satellites are widely scattered in the sky; on the

contrary, accuracy is reduced when the satellites have gathered in a narrow space.

In the following figure, in both cases it is possible to obtain the GPS fix, but in the

left case the accuracy will be higher than the right:

Fig. 1.3b - HDOP

The index for position-fixing accuracy is called HDOP ("Horizontal Dilution Of Pre-

cision", see also Chapter 7 for the HDOP definition).

The HDOP value indicates higher position accuracy. Ranges of 1.0 to 1.2 provide

the highest degree of accuracy. Higher values indicate less position accuracy. This

is due to the satellites being gathered in a narrow space. Satellites which are

widely scattered in the sky produce the highest degree of accuracy.