ADC Telecommunications Inc. PSM07U2D Benutzerhandbuch

©

 

2011 ADC Telecommunications, Inc

ADCP-77-177  • Issue 

1 • July 2011

In a FlexWave Prism system, each BTS provides the RF channel inputs and outputs 

for a designated sector. Each Host may be interfaced with one or more Base 

Transceiver Station (BTS). 
On the forward path, the Host receives Analog RF signals from the BTS, digitizes 

the designated RF bands, and then transports them over single-mode fiber to up 

to 8 Remote Units. The Remote Unit(s) receives the digitized spectrum from the 

Host and converts the spectrum back into an analog RF signal to be distributed via 

an externally mounted antenna system.
On the reverse path, the Remote Unit digitizes the designated RF spectrum and 

digitally transports it over single mode fiber or Millimeter Wave (MMW) to the 

Host. The Host receives the digitized RF signals from the Remote Unit and converts 

them back to Analog RF for the BTS.
In a typical Prism system the Host is connected to the Remote using two 

single-mode optical fibers. One fiber is used to transport the forward path optical 

signal and a second fiber is used to transport the reverse path optical signal. 

Because the optical signal is digital, the input and output RF signal levels at the 

Host or the Remote are not dependent on the level of the optical signal or the 

length of the optical fiber. A diagram of the standard fiber optic transport system 

for both a non-diversity and diversity system is shown in 

. 

Figure 6. Standard Fiber Optic Transport Application

The maximum length of the optical links is dependent on the loss specifications of 

the optical fiber and the losses imposed by the various connectors and splices. The 

system provides an optical budget of 25 dB (typical) when used with 9/125 

single-mode fiber. There must be at least 10 dB of optical loss to prevent 

over-driving and possible damage to the optical receiver. 

77073-008

Remote

Unit

Forward Path

Reverse Path

Non-Diversity Fiber Optic Link

Forward Path

Diversity Fiber Optic Link

Reverse Path

And

Diversity Reverse Path

Host

Unit

Remote

Unit

Up To

Eight