Sensing and Internet of Things
35
Installation and Technical Manual for the
Limitless™ Multi-Protocol Receiver, WMPR Series
ISSUE B
32309669
Fade-margin is the amount of excess power available above
and beyond what is necessary to maintain a reliable RF signal
between the transmitter and receiver. Normally, an acceptable
threshold of excess power to ensure effective operation in a
variety of environmental conditions is 10 dB. A simple way to
determine if the signal strength is sufficient is to temporar-
ily install a 10 dB attenuator* between the RP-SMA plug of
the antenna or remote cable and WMPR’s RP-SMA jack. This
should be completed in an operating application environment
with good nominal environmental conditions. Starting with the
antenna chosen in Section 3 & 8.3, install the attenuator and
operate the system until exposure of all normal application
conditions is completed while monitoring the Lost RF Signal
Output. If the fade-margin is unacceptable, the lost RF sig-
nal output changes state) indicating the antenna position on
the Limitless™ switch and/or WMPR receiver will need to be
changed and/or another antenna type should be chosen. The
RF Signal indication within the Node Status menu or Node
Information Menu is useful in indicating the RF Link Strength;
refer to Sections 6.3 or 6.5 for more information.
Try several mounting locations and/or antennas along with
retesting each with the attenuator to determine the optimal
set-up that provides an acceptable fade-margin. Remove the
attenuator after testing is completed.
*Suggested sources/part numbers
•
10 dB attenuator (i.e. Crystek – Part number: CAT-
TEN-0100)
•
RP-SMA female to SMA male connector adaptor (i.e. Con-
nector City – Part number : ADP-SMAM-RPSF)
•
RP-SMA male to SMA female connector adaptor (i.e. Con-
nector City – Part number : ADP-RPSM-SMAF)
