Specifications

DELTA LTL-XL Retroreflectometer 25

The GPS position data, HDOP value, and the number of satellites used in the position calcula-

tion are saved in the log together with the R

and Qd data.

Activating the GPS

Press the MENU button and select SETTINGS / AUX, highlight the GPS line and press the OK

button to toggle the GPS ON or OFF. Press the BACK button or the HOME button to return to

the HOME screen.

The GPS data can be viewed from the HOME screen by pressing the UP button and then high-

lighting the GPS icon by using LEFT or RIGHT buttons. Press the OK button to display the

GPS data. When the GPS data changes the display is updated.

If the GPS does not fix and a measurement is taken a warning menu appears. You will be pre-

sented with the following option:

 No GPS fix, Measure anyway, NO / YES

More about the GPS

The GPS unit will typically acquire satellite signals and process a position fix in 1-15 se-

conds. If the GPS receiver has been turned off for a long period of time (>1 week), the time to

first fix will take longer.

The GPS engine used has a navigation performance of 2.5 m CEP

The precision of the GPS receiver in the LTL-XL is determined by many factors. A few are

listed below:

 Signal obstruction. The GPS receiver requires a clear view of the sky. Trees, build-

ings and other environmental objects may affect the satellite signals.

 Satellite constellation and geometry.

 Multi path (reflection of signal from buildings etc.).

The HDOP (Horizontal Dilution of Precision) is a number that indicates the quality and preci-

sion of the received GPS data (low values are better than high).

When the GPS is used, the operating time for the LTL-XL will be decreased and you may

have to charge the battery more often.

CEP (Circular Error Probable):

A statistical measure of the horizontal precision. The CEP value is defined as a circle's radius, when

centered at the true position, encloses 50% of the data points in a horizontal scatter plot. Thus, half the

data points are within a 2-D CEP circle and half are outside the circle.

Setup

Setup is used to separate between basic and advanced users. The basic settings reduce the

number of menus available to the user. For example, in basic menu operation, users cannot

clear the log.