Elpro Technologies 905U-D User Manual download pdf (Page 11)

Chapter Two Installation

Page 11 © January 2011

Chapter Two INSTALLATION

2.1 General

The 905U-D module is housed in an rugged aluminum case, suitable for DIN-rail mounting.

Terminals will accept wires up to 12 gauge (2.5 sqmm) in size.

All connections to the module must be SELV. Normal 110-240V mains supply should not

be connected to any terminal of the 905U-D module. Refer to Section 2.3 Power Supply.

Before installing a new system, it is preferable to bench test the complete system. Configuration

problems are easier to recognize when the system units are adjacent. Following installation, the

most common problem is poor communications caused by incorrectly installed antennas, or radio

interference on the same channel, or the radio path being inadequate. If the radio path is a

problem (ie path too long, or obstructions in the way), then higher performance antennas or a

higher mounting point for the antenna may rectify the problem. Alternately, use an intermediate

905U-D Module as a repeater.

The foldout sheet 905U-D

Installation Guide provides an installation drawing appropriate to

most applications. Further information is detailed below.

Each 905U-D module should be effectively earthed via the "GND" terminal on the 905U-D

module - this is to ensure that the surge protection circuits inside the 905U-D module are

effective.

2.2 Antenna Installation

The 905U-D module will operate reliably over large distances. The distance which may be

reliably achieved will vary with each application - depending on the type and location of

antennas, the degree of radio interference, and obstructions (such as hills or trees) to the radio

path. Typical reliable distances are :

USA/Canada 15 miles 6dB net gain antenna configuration permitted (4W ERP)

Australia/NZ 12 km unity gain antenna configuration (1W ERP)

Longer distances can be achieved if one antenna is mounted on top of a hill.

To achieve the maximum transmission distance, the antennas should be raised above

intermediate obstructions so the radio path is true “line of sight”. Because of the curvature of the

earth, the antennas will need to be elevated at least 15 feet (5 metres) above ground for paths

greater than 3 miles (5 km). The modules will operate reliably with some obstruction of the

radio path, although the reliable distance will be reduced. Obstructions which are close to either

antenna will have more of a blocking affect than obstructions in the middle of the radio path.

For example, a group of trees around the antenna is a larger obstruction than a group of trees

further away from the antenna. The 905U modules provide a test feature which displays the

radio signal strength.

Line-of-sight paths re only necessary to obtain the maximum range. Obstructions will reduce

the range, however may not prevent a reliable path. A larger amount of obstruction can be

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Elpro Technologies 905U-D User Manual Page 11