User's Manual

CI Wireless Inc.
1211 Ira E. Woods Ave., Grapevine, TX 76051
16
5.0 DESCRIPTION OF THE MICROCELL UNIT MODULES
5.1
Fiber Optic Transceiver
The Fiber Optic Transceiver provides the RF signal transmission and reception
via the fiber optic cable between the hub and microcell units. Alarm monitor
outputs are provided to the control module to provide real time monitoring of the
operational performance. The down link received optical signal is 1550 nm
wavelength and the up link transmitted optical signal is 1310 nm wavelength.
5.1b
Fiber Optic Slave, with Dual Transmitters and a Single Receiver
This optical tranceiver module accomidates the additional up link transmit path
required for diversity receive option. The unit has a single down link photo
diode receiver (Channel C RF Out) and two 1300 mm lasers (Channel A main
receiver and Channel B diversity receive) combined together with an internal
WDM allowing single fiber operation. RF Modem uplink is on Channel A.
5.2
RF Modem
The RF Modem module provides several functions in the RF signal path. The
modem provides the data receive and data transmit path, via RS485, between the
hub and the microcell units. The data is received on a RF carrier on the down
link path on a channel between 460 to 512 MHz and transmitted on the up link
path on the same channel carrier. The down link modem carrier is decoupled
from the PCS carrier signals with a directional coupler or triplexer and a low pass
filter. The PCS up link carrier signals from the LNA/Driver module are coupled
to the fiber optic module input combined with the RF modem carrier with a
directional coupler or triplexer
.
5.3
LNA/Driver Module
The LNA/Driver module is divided into two sections. The LNA section which
has moderate gain and a very high third order intercept point of 32 dBm and a
low noise figure of <1.5 dB. The LNA is coupled outside of the module through
a SMA/F connector to a band selective band pass filter. Future options, which
may require higher selective filtering, utilizing active filtering can also be
accommodated. Optional filtering could allow channel selective or tighter band
selective filtering. The high performance LNA achieves a superior system
dynamic range. This prevents overdrive from undesired out of band signals
which are could be received at higher than desired signal levels.
The driver input is coupled into the module through a SMA/F connector. The
driver has limit peaking of high level injected signals which will prevent
overdriving and damaging the laser. Overall gain of the LNA and driver is 49
dB. This provides for maximum sensitivity of the system at the maximum
allowable optical loss of 10 dB. (10 dB of optical loss is equal to 20 dB RF loss.
This insures an overall system noise figure of <6 dB.
Versions of LNA/Driver Modules:
1.850 - 1.910 GHz
806 - 849 MHz