Sony Ericsson GR64 - Manual (Page 79)

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It is recommended that you use a cable with a maximum resistance of
5 milliohm for the ground connection.
AREFand GND are connected at a single point inside the wireless
modem. They must not be joined together in your application.
7.4.2.3 Audio
Use a coupling capacitor in AUXI line if the application does not use the wireless
modem’s bias voltage. See also Figure 5.9-1 Microphone connections to the wireless
modem, page 52.
7.4.2.4 Software Upgrade
There are two ways of updating the firmware in the GR64. There is a web-based tool
that can access a Sony Ericsson server from where SW can be downloaded. There also
is an Updater, which is a local application that downloads an image provided by
SEMC.
7.5 Antenna
7.5.1 General
The antenna is the component in the users system that maintains the radio link
between the network and the wireless modem. Since the antenna transmits and
receives electromagnetic energy, its efficient function will depend on:
• Type of antenna (for example, circular or directional)
• 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, users should contact their local antenna manufacturer for additional
information concerning antenna type, cables, connectors, antenna placement, and
the surrounding area. Users should also determine whether the antenna needs to be
grounded or not. Usually, a local antenna manufacturer should be able to design a
special antenna suitable for the integrators application and environment.
7.5.2 Antenna Type
Users should ensure that they choose the right type of antenna for the wireless
modem.
NOTE