Operating Instructions
LMS5xx
Product description
8013796/ZM63/2017-05-09 © SICK AG · Germany · All rights reserved · Subject to change without notice 37
Chapter 3
In bad weather conditions (rain/snow/fog), the LAST ECHO filter can produce better results
or actually make special applications possible such as measurement through a window.
Recommendation If measurement through a window is necessary, then a slight inclination of the window
versus the sensor (<> 90°) is recommended to avoid any direct reflections on the sensor
(mirror effect).
3.9.5 RSSI values
RSSI (Received Signal Strength Indicator) is the measurement of power received by the
sensor. This value is generated for every measurement and has an arbitrary unit with a
logarithmic characteristic. The RSSI values have an 8-bit resolution, with integer values
from 1 to 255, where 1 is the weakest signal and 254 the strongest signal (e.g. with a
reflector). A value of 255 means “dazzled”. The value 0 (zero) means that the received
power was too low to generate a valid RSSI value. If there is a valid distance measurement
it has a minimum RSSI of 1.
Fig. 20 and Fig. 21 show the different approximate curves for the RSSI ranges of the HR and
SR variants depending on the object remission, with 10% being the lowest (black), and
100% the highest (white paper). The value of > 80,000% represents a reflector. This is the
reason why the resulting curve remains constantly at 254.
If the RSSI value is 0, then no distance measurement is possible. Two reasons are possible:
Target object is out of range (> 80 m).
Target object has an extremely low remission.
Please note that white paper (100%) at close range can give very similar values as a
reflector.
Fig. 20: Typical RSSI values HR
RSSI value Description
0No signal
1-254 Valid measurement
255 Dazzled
Tab. 14: RSSI values
RSSI [digit]
Distance [m]
White (approx. 100%)
Grey (approx. 50 %)
Black (approx. 10 %)
Reflector (> 80,000 %)
Max. signal
To Next Page
Loading...
Need help?
General
