PTP 800 Series User Guide Indoor RF unit (IRFU)
phn-2513_004v000 (Oct 2012)
1-19
Transceivers
Each transceiver provides the necessary frequency conversion and amplification of signals
which pass between the CMU and antenna. In the transmit direction, a transceiver
up-converts and amplifies the fixed intermediate frequency (IF) signal received from the
CMU resulting in a configured licensed band radio frequency signal transmitted at the
waveguide interface. In the receive direction, a transceiver provides low noise
amplification and down-conversion of the licensed band signal received at the waveguide
interface. The result is a fixed IF signal which is passed to the CMU for demodulation.
Each transceiver is powered via its own dedicated power socket. Cambium Networks do
not provide the power supply, but they do provide the power connector. For power supply
requirements, please see IRFU specifications on page 4-8.
To prevent grounding issues with the CMU, only a -48 V dc power supply is supported.
Each transceiver is cooled by its own field replaceable fan assembly. Each fan assembly
contains two fans which are automatically controlled by the transceiver which responds to
changes in the temperature of its power amplifier.
As an aid to aligning antennas, the IRFU provides an interface per transceiver for
monitoring the strength of the received signal level.
Branching unit
The transceivers connect to the waveguide interfaces via the IRFU branching unit. The
branching unit is an integral part of the IRFU and is situated at the back of the chassis.
The branching unit provides the necessary coupling and filtering and also the necessary
isolation between transceivers. Although the branching unit is not field replaceable, the
transmit and receive filters within the branching unit are both field replaceable.
IRFU availability
IRFUs are available at 6 GHz and 11 GHz. The 6 GHz IRFU support the L6 and U6 bands
of both FCC and Industry Canada regulations. The FCC 7 GHz band is also supported by
this IRFU. The 11 GHz IRFU supports the 11 GHz band for both FCC and Industry Canada
regulations.
Although the transceivers are designed to cover the entire frequency range of a given
band, the branching unit is factory tuned for a specific transmit frequency and a specific
receive frequency. The transmit frequency and receive frequency must therefore be
specified when ordering an IRFU.
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