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IES-5000/5005/6000 Support Notes
49
Impulse Noise Protection (INP)
The impulse noise generator is required to prove the burst noise immunity of the VDSL
transceiver. The noise shall consist of bursts of additive white Gaussian noise (AWGN)
injected onto the line with sufficient power to ensure effective erasure of the data for the period
of the burst, i.e., the bit error ratio during the burst shall be approximately 0.5 (assuming FEC
is not applied). The noise burst shall be applied regularly at a repetition rate of at least 1 Hz.
The duration of the burst is variable; at least values of 10, 50, 100, 250, and 500 μs shall be
supported. The AWGN shall be generated with crest-factor of 5 and flat PSD up to 12 MHz,
and further continuously declined with a roll-off equal to or steeper than 12 dB per octave. The
PSD of the AWGN shall be variable in the range from –70 dBm/Hz to –140 dBm/Hz.
Interleaving shall be used to protect the data against bursts of errors by spreading the errors
over a number of Reed-Solomon codewords. Interleaving can be programmable by software.
Sudden strike noise can cause packet error. A buffer to protect ADSL Physical connection.
Error ratio during the burst shall be approximately 0.5 (assuming FEC is not applied). The
noise burst shall be applied regularly at a repetition rate of at least 1 Hz. The duration of the
burst is variable; at least values of 10, 50, 100, 250, and 500 μs shall be supported. The
AWGN shall be generated with crest-factor of 5 and flat PSD up to 12 MHz, and further
continuously declined with a roll-off equal to or steeper than 12 dB per octave. The PSD of the
AWGN shall be variable in the range from –70 dBm/Hz to –140 dBm/Hz.
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