Deaf - Safran CORTEX CRT Quantum User Manual

3.3.15.2.DEAF

The DEAF feature implemented on the Cortex CRT performs a blind equalization that allows recovering a signal
affected by amplitude and/or phase distortions. It is available on direct PCM demodulation chains, and it is
license dependent.
The effect of the DEAF can be seen in the figure below. A test signal (QPSK, 1 Mbps, RRC 0.5) has been
strongly distorted by a frequency-selective channel and corrupted by AWGN noise (80 dBHz that would give
Eb/N0 20 dB without distortion):
Without equalization, the measured Eb/N0 of the received signal is very low (4 dB). That can be seen on the
constellation plot of the signal, where the effect of ISI is clear:
© Safran Data Systems
COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
Figure 46: Spectrum of the test signal
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Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
Page 104