Compact modem unit (CMU) Chapter 1: Product description
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phn-2513_004v000 (Oct 2012)
Compact modem unit (CMU)
This section describes the PTP 800 CMU and its interfaces.
CMU description
The PTP 800 compact modem unit (CMU) (Figure 3) is mounted indoors and provides the
Ethernet interface to the network. It converts the Ethernet frames to a data stream which
then modulates an intermediate frequency (IF) signal which is sent to the radio frequency
unit (RFU), either an outdoor unit (ODU) or an indoor radio frequency unit (IRFU).
In the other direction, the CMU demodulates a similar IF signal from the RFU and
reconstructs Ethernet frames to send to the network. Both IF signals are carried over a
coaxial IF cable connecting the CMU to the RFU. The CMU also provides power to the
ODU and this is also carried over the coaxial cable. The IRFU is powered separately.
The CMU is mounted on a shelf, on a wall (using the provided bracket), or in a standard
19 inch rack (using the optional CMU rack mounting kit). It is ideally suited to applications
where space is limited.
Figure 3 PTP 800 CMU
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