Delta RetroSign GRX-1, User Manual

Page: 52 / 80

RetroSign GRX User Manual / December 2017
52
DELTA
Calibration
The RetroSign GRX is factory calibrated.
In order to ensure high quality of data DELTA recommends calibrating the RetroSign GRX once a
day, typically in the morning, before commencing the measurements.
The calibration process automatically compensates for instrument offsets etc.
It is possible to make two different types of calibrations:
•
Reference calibration
•
Dark calib reference calibration
Normally, it is sufficient to make a reference calibration of the GRX instrument prior to conducting
measurements. However, it is recommended to do a dark calibration now and then.
A simple way to test if dark calibration is needed is to point the GRX, and measure in a direction with
no retroreflective objects (i.e. shiny surfaces, windows, edges, and lamps etc.) within a distance of at
least 10 meters / 33 feet in front of the RetroSign GRX. The result of this measurement should be
zero, or at least no more than 1-3. If you get a higher value, there might be some contamination on
the optical lens. In this case clean the optics and check again.
A dark calibration (followed by a reference calibration) is then recommended in order to perform
correct measurements.
To calibrate the GRX instrument select
‘Calibrate’ from the main menu.
How to perform a reference calibration
•
Fill out the fields : type in the calibration values printed on the calibration target or scan them
from the calibration target by selecting ‘Scan barcode’ and place the barcode in front of the
reader: