User manual

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4.2 How to install the modem
4.2.1 Power supply
Use a high-quality power supply cable with low resistance. This ensures that the voltages at the connector
pins are within the allowed range, even during the maximum peak current.
When the unit is powered from a battery or a high current supply, connect a fast 1.25A fuse in line with
the positive supply. This protects the power cabling and modem.
4.2.2 Securing the modem
Before securing the modem take into account the amount of additional space required for the mating
connectors and cables that will be used in the application.
Where access is restricted, it may be easier to connect all the cables to the modem prior to securing it in
the application.
Securely attach the HT910 Terminal modem to the host application using two 3mm diameter pan-head
screws
4.3 Antenna
4.3.1 General
The antenna is the component in your system that maintains the radio link between the network and
the modem. Since the antenna transmits and receives electromagnetic energy, its efficient function will
depend on:
the type of antenna (for example, circular or directional);
the placement of the antenna;
communication disturbances in the vicinity in which the antenna operates.
In the sections below, issues concerning antenna type, antenna placement, antenna cable, and possible
communication disturbances are addressed. In any event, you should contact your local antenna
manufacturer for additional information concerning antenna type, cables, connectors, antenna
placement, and the surrounding area. You should also determine whether the antenna needs to be
grounded or not. Your local antenna manufacturer might be able to design a special antenna suitable
for the application.
4.3.2 Antenna type
Make sure that you choose the right type of antenna for the modem. Consider the following
requirements:
the antenna must be designed for the one of the frequency bands in use; please ask your network
provider for more information:
o GSM 900/2100 MHz
o EDGE 900 / 1800 / 1900 MHz
o UMTS 900/2100 MHz
the impedance of the antenna and antenna cable must be 50Ω;
the antenna output-power handling must be a minimum of 2W;
the VSWR value should be less than 3:1 to avoid any damage to the modem.