| 摘要 |
<p>A system for distributing HDTV signals from a head station (1) to a number of customer stations (3) includes a single head-end optical source (4) having a frequency f0 and a modulator (5) arranged to receive light from the single optical source (4). The modulator (5) modulates the light with a sub-carrier multiplex of n channels, where n is an integer greater than 2, the n channels having frequencies f1, f2...fn. The frequencies are separated in frequency-space from each other and from f0. A broadband passive branched optical network (2) is connected to the output of the modulator (5) and arranged to distribute the modulated signal from the head station (1) to a plurality of customer stations (3) each having a coherent heterodyne receiver (7, 8, 9, 16).</p> |
