Installation & Operation Manual Chapter 2

FibeAir 1500 Installation & Operation Manual Chapter 2. Theory of Operation
Revision 2.0 In Door Unit (IDU) 2-3
2.2.2. MODEM
The FibeAir 1500 is equipped with a 16-states QAM Modem. The modem
delivers a 155 Mb/s payload in 50/56 MHz channel bandwidth in compliance
with FCC/ETSI standards. The Modem is equipped with Digital Signal
Processing functions as follows:
n Digital IF - I/Q modulator/demodulator whose functions are:
⇒ Conversion of the modulated signal to/from the IF frequency.
⇒ Automatic level equalization on the signal from ODU.
⇒ Protection against overloads.
n Timing recovery techniques employing digital tracking loop.
n FEC ensures unfaded BER lower than 10
-13
.
The following figure illustrates a measured 16 QAM constellation.
Figure 2-2 16 QAM Constellation