Promax HD RANGER, User Manual

Page: 86 / 92

A1.1.6.2 DVB-C Measurements
Power
Channel power, assuming that power spectral density is uniform over the
entire bandwidth of the channel.
C/N
(Carrier / Noise) where C is the received power of the modulated carrier
signal and N is the noise power received. To measure it correctly the channel
should be tuned at its centre frequency.
MER
Modulation Error ratio with indication of Link Margin(LM).The link margin
indicates the safety margin respect to the MER level , measured for the
degradation of the signal up to the QEF (Quasi Error Free) value. MER
represents the ratio between the average power of the DVB signal and the
average noise power of the signal constellation.
BER (CBER)
It is the system error rate. In a digital signal reception via cable, after the
QAM demodulator an error correction method is applied, called Reed-
Solomon. The error rate after correction is less than the error rate at the
output of the QAM demodulator. For this reason the BER is given prior to
error correction.
CBER
BER measurement for digital signal before the error correction (BER before
FEC)
10 August 2012