US Cable Operator Time Warner has recently installed an 18 GHz digital microwave system to transport 256-QAM modulated carriers from the Hawaiian island of Maui to three separate receiving points.

The company chose a Cable AML microwave system consisting of a transmitter at the Headend in Huejutla, a repeater at San Francisco and receivers at each of the 3 towns.The islands of Molokai and Lanai and the isolated town of Hanna in Hawaii receive Cable TV signals (54 to 600MHz) from the main Headend in Maui via 13GHz broadband microwave links from Cable AML. Time Warner wanted to expand this carriage to include the 256-QAM digital video services (with carriers above 600MHz on the Maui cable system), but regulatory bandwidth limitations in the 13 GHz band made it necessary to use the18 GHz band for the digital carriers.The 15 mile link to Lanai and the 13 mile link to Molokai, both over water, were straightforward for the 256-QAM digital video.

The link to Hanna was more demanding due to two factors: a longer distance and the existing double passive reflector (billboards) in the path. The reflectors were designed for 13 GHz and had unknown performance characteristics at 18GHz.An additional requirement was that the link had to work using existing 13 GHz antennas at the transmitter site in Maui due to size restrictions imposed by National Park authorities. This was accomplished by using specially designed dual-frequency feed horns sharing the same antenna aperture.

Howard Feig was the Time Warner Engineer who designed, installed and commissioned the microwave hardware manufactured by Cable AML for this link. According to Howard, “Cable AML once again has provided an excellent solution for a very demanding link, continuing a tradition of good quality equipment and service lasting for over 15 years.”