Delta PG-40 Specifications download pdf (Page 28)

28 LTL-X Retrometer DELTA

It is not possible to see which correction system was used.

For further information about the GPS system and WAAS / EGNOS webpages can be found

that describe the systems and how they function.

Map datum.

The default map datum system is WGS84. There are more than 200 different map datums that

can be selected. The selected datum can be seen in the GPS menu.

The datum information is also stored in the log.

Warning: Selecting the wrong map datum can result is substantial position errors!

For further information on selecting the correct map datum system, please contact your local

mapping software distributor.

Contact your local distributor for futher information on changing the map datum in LTL-X.

More about the GPS

The GPS unit will typically acquire satellite signals and process a position fix in 5-40 sec-

onds. If the GPS receiver has been turned off for a long period of time, the time to first fix

will take longer.

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

The precision of the GPS receiver in the LTL-X 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 can 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-X will be decreased and you must

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 advanced or basic users. The basic settings reduce the num-

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

the log.

The following menu points can be selected in basic mode:

Settings: user, date & time, display, sound, setup.

Log: status.

Diagnosis.

Print/output.

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Delta PG-40 Specifications Page 28