Digital Channel Modules (Dcm) / Rf Cards; Figure 4-6 Single-Band Dcm, Rf Card, Low / Medium Power (Left) And High Power With Additional Dl Amplifier (Right); Figure 4-7 Dual Band Dcm, Rf Card (Medium Power) - CommScope Node AM4 Manual

4. Functional Description

4.3.2. Digital Channel Modules (DCM) / RF Cards

The digital channel module (DCM) is the RF digital-converter in both directions for
Downlink and Uplink. The Downlink and Uplink will be separated in the duplexer and the
desired signal will be amplified by an LNA which is – like the duplexer – an integrated part
of the RF card. The RF card down-converts the signals to the IF and converts the
analogue signal into a digital signal. Digital filtering / signal processing is done at the main
board of the subrack with single band RF cards, and with dual-band RF cards in the cards
themselves. Then, the digital signal is converted into an analogue signal, is up-converted
and amplified. Finally, the signal is sent to the PA (internal PA or mounted on the RF card)
and combined with the other link in the second duplexer.
The following figure shows the single band DCM, RF cards:
figure 4-4 Single-band DCM, RF card, low / medium power (left) and high power with
Optionally, medium power dual band RF cards
are available, by which two bands, for instance
the 800/900 bands or the 1800/2100 bands,
can be combined in one module. Thus, the
maximum number of bands per Node AM can
be increased to up to 8*.
Apart from the difference in digital signal
processing as explained
functionality of dual-band and single-band RF
cards is principally identical.
* up to 7 with 680 W PSU
With certain RF cards, use of a slot duplexer is obligatory. This duplexer is installed in an
RF card slot, i.e. if such a duplexer is equipped, maximally three RF cards are available.
For details on the card types see chapter 8.
MF0121ACP_uc.docx
additional DL amplifier (right)
above, the
figure 4-5 Dual band DCM, RF card (medium power)
Manual for Node AM4 Page 39