Campbell CRVW3, Instruction Manual

Page: 78 / 135

CRVW3 3-Channel Vibrating-Wire Datalogger
65
10.2.2 Planning for CRVW3 End-node Stations
Using the locations mapped in Section 10.2.1 , Sensor Planning
(p. 64)
, plan out
how each sensor will connect with a CRVW3 device. To minimize the required
number of stations, plan for three sensors to connect to each CRVW3
whenever possible. Indicate on a map where the CRVW3 stations will be
located.
FIGURE 10-4. Each Sensor Connects to a CRVW3
The length of cable between the sensor and the CRVW3 is a factor to consider.
The distance between the CRVW3 and the measured sensor can be up to
1600 m in many instances. Long cable distances (> 500 m) should be validated
for proper operation using careful field experimentation. Cabling distances
shorter than 500 m can usually work well with lower excitation levels (5 V
instead of 12 V) which saves on power consumed during the measurement
cycle. Document the length of cabling that will enable each sensor to connect
with a CRVW3.
Plan for each CRVW3 to have a line-of-sight radio connection with a repeater
station (which can be another CRVW3) or with the base station. A CRVW3
end-node station will communicate with only one remote radio station. The
location of a CRVW3 may need to be adjusted to allow for a satisfactory radio
communications link. Some field-based groundwork may be necessary to
determine radio strength capabilities between potential station sites (see
Section 10.2.8.1 ,
Pre-procurement Field Visits
(p. 71)
).
If the remote station is within a close enough distance to the CRVW3, a whip
antenna can be used. However, for longer distances a high-gain antenna will be
needed. A Yagi antenna is recommended for a CRVW3 end-node station
because of its high gain and directional beaming capability.
For specific information relating to CRVW3 end-node stations, see Section
10.2.6 , Planning RF451 Radio Networks
(p. 68)
, or Section 10.2.7 , Planning
RF407 Radio Networks
(p. 69)
.