Jamar RAC Geo II, User Manual, Page: 7 / 60

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Chapter 1 — Introduction
What is the RAC Geo II?
The JAMAR Technologies Road Analysis Computer (RAC) Geo II is an
accurate, easy-to-use distance measuring instrument (DMI) that incorporates
GPS technology.
The RAC Geo II has been designed with features to provide you with
a versatile and functional instrument that can be learned in a very short
time. This cost-effective unit saves time & money by allowing personnel
to measure distance, accurate up to 1 foot per mile, while recording GPS
coordinates of roadway features.
How does it work?
The RAC Geo II has an on-board GPS receiver built into the unit. Once it
locks onto the GPS satellites, it can track movement. Power is provided
by a 12V auto adapter, which makes the unit completely portable from
vehicle to vehicle. (Power can also come from any existing DMI power
wiring if you already have this.)
While the on-board GPS receiver will track distance, we recommend the
use of the external GPS antenna for the best accuracy. This screws into the
top of the Geo II and comes with the unit.
Accuracy using GPS-based distance measuring is approximately 1 foot
per 1000 feet. If you require greater accuracy, an external distance sen-
sor (such as a modular or magnetic sensor) can be used with the unit to
provide accuracy up to 1 foot per mile (5280 feet). Information on using
an external distance sensor can be found in Chapter 4.
In addition to distance measuring, the RAC Geo II also has the unique
ability to track and store GPS coordinates using the on-board GPS re-
ceiver. The GPS coordinates of road features (intersections, bridges, signs,
guardrails, etc.) can then either be internally stored for download to the
RACPro software, or read directly off the RAC's display.