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3.
4.
5.
Recommendations for Handling the Interference Sources
On a PC, there are various interference sources, such as the LCD, CPU, audio
circuits, and power supply. All the interference sources emit interference signals that
affect the normal operation of the module. For example, the module sensitivity can be
decreased due to interference signals. Therefore, during the design, you need to
consider how to lessen the effects of interference sources on the module. You can
take the following measures: Use an LCD with optimized performance; shield the
LCD interference signals; shield the signal cable of the PC; or design filter circuits.
4.4 Offline Mode
The offline mode can be enabled by the following methods:
l
l
For the offline mode, the following customizations can be realized on the firmware:
1.
2.
3.
4.
All the preceding customized states are set before the module is delivered and
cannot be changed by the end users.
Huawei Confidential: This documents is Huawei Proprietary and Confidential(NDA
Issue 1
Required).It may not be duplicated, neither distributed externally without
(2008-09-15)
prior and written permission of Huawei.
You are recommended to design the antenna pattern as the horizontal polarized
omnidirectional pattern that facilitates the reception of strong signals especially
in outdoor environments.
Besides the module antennas, a PC has other internal antennas, such as the
WLAN antenna. Therefore, when designing the module antennas, the
requirement on the isolation between module antennas and other PC antennas
should be considered (the recommended value is listed in Table 4-7). Keep
proper distance between antennas if possible. To reduce the interference
between antennas, it is not recommended that an antenna is designed closely
next to another one.
Carefully design the metallic components (such as the external frame of the
metallic shell) in and near the antenna area with considering the effects on the
antenna performance (such as whether the frequency offset of the antenna
occurs and whether the antenna pattern is deformed).
Through hardware: The W_DISABLE pin can be used to control the RF circuit.
When the pin is driven to the high level, the RF circuit works; when the pin is
driven to the low level, the RF circuit does not work.
Through software: The AT command of AT^RFSWITCH can be used to control
and query the status of the RF circuit.
The RF circuit works each time the module is powered on.
The RF circuit does not work each time the module is powered on.
When the module is powered on for the first time, the RF circuit works, and then
the module can remember the users' operations.
When the module is powered on for the first time, the RF circuit does not work,
and then the module can remember the users' operations.
HUAWEI EM770 HSPA PC Embedded Module V100R001
Product Specification
Page
35 of 68
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