Campbell NL241, Instruction Manual

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NL241 Wireless Network Link Interface
15
RSSI in the NL241 is measured in a scale between –100 dBm and 0 dBm. The
higher the number (for example, –12 dBm as compared to –72 dBm), the better
the connection between Wi-Fi devices. A reliable connection will be
maintained if the RSSI reading in the NL241 stays between –85 dBm and –15
dBm. A weak, and thus intermittent, connection will have readings between –
85 dBm and –95 dBm. For every 3 dBm increase, the NL241 is receiving twice
as much signal (radiated power). For every 3 dBm lost, the NL241 is receiving
50% less signal.
To improve your RSSI readings, shorten antenna cable lengths and use
frequency-matched antennas with higher gain. An NL241 with a 0 db gain
antenna can achieve ranges of up to 32 meters (120 feet) indoors and 95 meters
(300 feet) outdoors. Ranges can be improved by installing higher gain antennas
on both the NL241 and/or the wireless access point. Remember that RSSI can
also be affected by weather, vegetation, terrain, interference, and antenna cable
length and type.
6.4 Antennas
Antenna selection and placement can greatly affect the strength of the signal
you transmit and receive and therefore can impact the quality of
communications with your device. The NL241 should be paired with an
antenna designed for Wi-Fi communications at 2.4 GHz (2.401 to 2.483 GHz).
Ideally the antenna will be connected directly to the NL241 or positioned in
such a way as to minimize coaxial cable length. Note that coaxial cables
attenuate signals more as frequency increases; care should be taken when
selecting the type and length of coaxial cable used with the NL241. The NL241
antenna connector is RPSMA male. When connecting directly to the NL241,
select a coaxial cable or antenna with a mating RPSMA female connector.
6.5 Power
One advantage of using the NL241 in your application is its low power
consumption capabilities. With careful planning, you can reduce your station
power needs while still meeting your critical communication needs. See
Section 5 ,
Specifications
(p. 11)
(Typical Power Consumption), and Appendix
C.2 , Wi-Fi Tab
(p. C-4)
, for more details.
6.6 LED
There is a bi-color LED on the NL241 that serves as an indicator as described
below.
Normal Operation
After power-up, the LED turns solid red while the NL241 is searching for and
trying to join a Wi-Fi network (or while creating a network).
After successfully joining or creating a network, the LED will flicker green
with network activity. Note that the LED may only blink green once every few
seconds on the created network or networks that aren’t very busy.
If the device is unsuccessful at joining or creating a network, the LED will
periodically double-strobe red. The device will attempt to connect to the
network again after approximately one minute.