Optical cable television transmission system

US5128790A · kind A · utility

Assignee

• Alcatel N.V. · NL

Inventors

• Rolf Heidemann · Zöblitz, DE
• Heinz Krimmel · Ditzingen, DE
• Berthold Wedding · Ditzingen, DE

Key dates

• Filing date: Sep 12, 1991
• Grant date: Jul 7, 1992
• Expiry date: Sep 12, 2011

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N7/22
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

To transmit a frequency-division multiplex signal occupying a broad frequency band, e.g., the 40-440 MHz cable television frequency band, over an optical-fiber transmission link, in the transmitter, the whole frequency band to be transmitted is converted by single-side-band amplitude modulation of a high-frequency carrier f.sub.0 to a higher-frequency band, e.g., 840-1240 MHz, which, referred to its lowest frequency, is less than one octave wide. Second-order intermodulations products, which usually result during electric-to-optical conversion, thus fall into unoccupied frequency ranges. At the receiving end, corresponding demodulation is performed employing either carrier recovery or a locally generated carrier. In a preferred embodiment, the frequency band to be transmitted is converted to the higher frequency band in several subbands.