US Cable Operator Cable One has upgraded a 23-mile FM link in Clarksdale, originally used to transport seven distant TV stations, to now transport SDTV and HDTV digital signals with 8VSB modulation.

Two AML links fed from the same transmitter were used to transport the 65 channels from the headend to the two towns at distances of 11 Kms and 25 Kms respectively. The second of the paths is mostly over water, crossing Lake Eronguaricaro.

The traditional way to transport HDTV signals, which was to demodulate them to ASI Transport Streams and then to transmit each one through a digital radio, is very expensive for a multi-carrier application. The method implemented by Cable AML is the least complex, least expensive and most reliable approach. The 8-VSB modulated, 6 MHz-wide digital signals were frequency-multiplexed and transported through a broadband Cable AML transmitter.

At the receive site the AML receiver delivers all the carriers on a single cable, which is linked to the headend. The 8VSB signals can be demodulated to ASI and/or baseband audio and video, depending on how they are to be used.

The antennas and waveguide previously used for the FM microwave were suitable for the broadband AML transport of the 8VSB signals. Using the same antennas and waveguide, allowed an electronics only upgrade to a digital link, minimizing the cost and installation time.