905U-L Wireless I/O Installation Manual
905U-L Wireless I/O
Page 15 of 40
Version 1.9
Radio transmission distances
The unit will operate reliably over large distances depending on the:
Antenna type
;
Antenna location
;
Amount of radio interference
; and
Radio path obstructions
(e.g. hills or trees).
Typical reliable distances are:
Area
Distance
Additional information
USA/Canada
20+ miles
6dB net gain antenna configuration permitted (4W Equivalent RF power permitted).
Australia/NZ
20+ km
Unity gain antenna configuration (1W Equivalent RF power permitted).
To achieve these distance, you must elevate at least one site on a hill or transmission
tower.
Modules will operate reliably with some radio path obstruction; however obstructions also
reduce the reliable distance.
Note
You must test all obstructed paths to check the reliability of the path.
You can achieve maximum transmission distances if
the radio path has “line of sight”. For
example, raising antennas above intermediate obstructions including hills, trees, etc.
Obstructions reduce the range; however they may not prevent a reliable path.
The closer the obstruction is to the antenna, the greater the blocking effect. For example,
a group of trees around the antenna is a larger obstruction than a group of trees further
away from the antenna. You can achieve longer distances by mounting one antenna on
top of a hill.
Note
Due to the earth’s curvature, you must elevate antennas higher than the ground level
between the antennas for longer paths (greater than 3 miles / 5 km).
The unit can tolerate larger amounts of obstructions for shorter distances. For very short
distances, you can also mount the antennas inside buildings.
If two 905U modules cannot communicate reliably, you can use a third 905U module as a
“repeater” to receive and re-transmit messages. This module may also have input/output
(I/O) signals connected to it and form part of the I/O network.
Note
1. ELPRO recommends using the 905U-G module as a repeater unit between 905U-L-T
and 905U-L-R modules.
2. To use a repeater unit, the 905U-L modules and the repeater module must be
configured using the supplied configuration software. The factory default configuration
described in the Quick Start Guide cannot use a repeater unit.
