Abstract

It is commonly proposed to deliver compressed digital video in hybrid CATV systems with tens of digital subcarriers operating in the rf frequency range (450-700 MHz) above the AM-virtual-sideband (AM-VSB) video subcarriers.^1,2 It is known that clipping distortion imposes limits on the modulation depth p. of all AM-VSB optical links and also generates errors in the digital subcarriers of hybrid systems.^2,3 We demonstrate that a hybrid system using differential quadrature-phase-shift-keyed (DQPSK) subcarriers is feasible, suffering only a 2-dB penalty due to the clipping distortion.

© 1994 Optical Society of America