A dual-band, two-way microwave system was recently installed by MSO Cable One in Morenci, Arizona, providing an all-digital wireless HFC extension capable of delivering the same Digital TV and DOCSIS cable modem services offered in the nearby Safford, Arizona system.

The wireless HFC system was selected over the two other possible alternatives: a fiber link from the Safford headend or a stand-alone headend. The main reason is that it is much more cost effective, which is a significant consideration when providing service for areas with under one thousand subscribers.

The Morenci system had previously received off-air broadcast signals from Safford via a two-hop FM microwave system. The links are 23.3 and 11.7 miles long respectively, for a total of 35 line-of-sight miles.

Cable One decided to implement an all-digital service. The microwave system operates with multiple carriers, all with 256-QAM modulation. The initial 13 GHz downstream transmission rate is 814 Mbps, but the system has capacity to transmit upwards of 3 Gbps.

The 18 GHz upstream was designed to accommodate multiple 16-QAM signals from each of the four nodes. With the increasingly symmetrical nature of subscriber data traffic, more than one upstream channel was required. Cable AML developed a synchronized, block-conversion system to transport four independent upstream channels (each from 5 to 42 MHz) through the two-hop microwave system back to Safford for integration into the CATV return network.

The upstream service in the 18GHz band required the installation of new antennas and waveguide jumpers at the transmitter site at Morenci, the repeater at Guthrie Peak and the receiver at Safford.