User's Manual

Fiber Optics Powerwave
4 - 6 Rev. P1A9-Draft 2004-11 VM100 56/EN – User’s Manual
7. Optical receiver
The optical receiver performs the opposite function to the optical transmitter. It contains
a light detector, that is a semiconductor photodiode that produces current in response to
incident 1310 or 1550nm light.
The conversion from an optical signal to an electrical RF signal is shown in Figure 4-4.
Figure 4-4. Optical receiver light detector
The optical input power to the light detector has to be between –15dBm and 1dBm. To
avoid detector saturation that will result in signal distortion, it should be less than 1dBm.
The optical output power is independent of the TX attenuation.
The light detector adds very low amounts of shot noise and thermal noise.
8. Amplifier
The converted electrical RF modulated signal is amplified in a 16dB amplifier with a
noise figure of 4dB.
9. Software adjustable attenuator
The software adjustable 0 – 20dB attenuator is set manually via an O&M software. This
is described in the FON section of the VM100 01/EN, OM-Online, User’s Manual.
Setting, see the following amplifier.
RX
P
O
I
I
RF
P
O-RF
16dB
0 – 20dB