Huawei NE05E Hardware Manual page 404

HUAWEI NE05E,NE08E
Hardware Guide
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The interference, from either inside or outside the equipment or the application
system, affects the equipment through conductive modes such as capacitance
coupling, inductance coupling, electromagnetic wave radiation, common
impedance (including grounding system) and cable (power and signal cables). In
terms of external relationships of the equipment, interference is from the signal
cable, power cable, grounding system and spatial electromagnetic wave.
Integrated circuits (ICs) have the interference resistance capability to a degree.
However when the external noises go beyond their anti-interference tolerance,
corrupted signals and even system malfunction will be caused. It is impossible to
eliminate or shield all the interference sources, but the following measures can be
taken to suppress the interference signals:
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Issue 05 (2023-03-31)
The corona discharge of the electric transmission line
The transformer
Switches
Waveform distortion of the power supply network caused during the
operation of large equipment
Radio frequency (RF) interference
Natural interference sources such as terrestrial magnetic field and external
radiation
High frequency interference in the power supply network is generated when
the primary coil of the power supply transformer is coupled to the secondary
coil through distributed capacitors. To suppress such interference, we can use
an appropriate transformer, and install a low-pass filter at the inlet of the
power supply cable.
The interference of the transient voltage in the power supply network can be
reduced by inputting power directly from the primary transformer with a filter
capacitor for router equipment.
When router equipment works in the 50 Hz mains power supply network with
the above interference, the surge voltage caused by the power supply network
and the over-voltage generated by lightening will be passed to the power
supply of the optical synchronous transmission equipment, which leads to
computing errors of the processors. Therefore, before directly using the mains
supply, effective measures against interference from power supply network
should be taken.
The key to eliminate the interference from the grounding system is to avoid
loops among various grounds, such as the signal ground (including analog
and digital grounds), BGND, PGND and shield ground, or loops formed by
large distributed capacitors. Otherwise, the common impedance interference
from the grounding system may affect the operation of the equipment. In
buildings other than high-rises, the working ground of router equipment
should be separated as far as possible from the ground for electricity
equipment and surge protection device.
Prevent electromagnetic radiation interference from the surroundings to the
equipment. In some integrated communication buildings, if there is a high
frequency transmitter there, its influence on router equipment should meet
the relevant requirements. Independent power supplies are recommended for
them.
EMI from the telecommunications line should be restrained. Influenced by
high frequency electromagnetic field (external interference), high longitudinal
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4 Hardware Installation and Parts Replacement
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