SHAPING THE FUTURE SATELLITE OF COMMUNICATIONS
8.5 Equalink
BER performance degradation due to transmission channel impairments is
becoming increasingly important in DVB-S2 systems operating with higher order
modulation formats (16APSK, 32APSK), in particular at the higher symbol rates.
The Equalink concept effectively optimises satellite link performance by
counteracting these effects. Newtec DVB-S2 modulators equipped with the
Equalink™ feature contain both linear and non-linear predistortion functions which
can be individually enabled/ disabled.
Equalink operating principle:
• Optimum predistortion is computed off-line based on specified distortion
characteristics;
• Resulting predistortion table(s) are uploaded to the modulator and activated.
Link performance can be expressed in terms of Bit or Packet Error Rate (BER or
PER) versus Energy-per-symbol to Noise density ratio (Es/No).
For a communication channel over a satellite link, the overall link performance can
be severely degraded by channel impairments. Examples of such impairments are
interference (Adjacent Channel Interference (ACI) and Co-Channel Interference
(CCI), Inter-Modulation (IM), Adjacent Satellite Interference (ASI)...), phase noise,
signal distortions, etc.
Please refer to the Equalink™ User Manual for a full description of
this feature.
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