This compact depth CWDM unit for (singlemode) SFW, allows 3 x RRU’s to be connected from the Exchange using a single optical fibre. Each RRU has separate transmit and receive optical signal wavelengths, that feed into a CWDM coupler. From the coupler the output optical wavelengths are fed by a single optical fibre to the Exchange. Monitoring points are provided for both the main Tx and Rx optical wavelengths. This is achieved by having a 2 x 2 – 90/10% splitter in the main incoming/outgoing single optical fibres. Here 90% of the optical signal goes direct to line whilst 10% of the optical signal goes to the monitoring port. This applies to both Tx and Rx optical signal streams. The 1RU CWDM subrack is housed in the Equipment Room at a Radio Site, or in an Exchange Rack.