The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 14, 1981
Filed:
Apr. 06, 1979
Gregoire Eumurian, Paris, FR;
Thomson-CSF, Paris, FR;
Abstract
A fiber-optical communication path between a transmitter and a receiver of electrical message signals forms a main channel and a shunt branch terminating at respective photodiodes from which incoming signals can be alternatively fed to an output terminal by way of an adjustable attenuator that is periodically reset, with the aid of a digitally operating automatic-gain-control loop in response to a pilot signal arriving over the same path. A code converter in that loop supplies binary words, representative of signal amplitude, to a comparator which determines whether the amplitude of a signal in the output of the main channel exceeds a given threshold and, in that case, causes a switchover to the shunt branch whose optical attenuation is substantially greater. The periodic emission of a pilot signal in lieu of a message signal is controlled by a setting instruction which, aside from enabling the resetting of the attenuator according to the instantaneous contents of the code converter, is sent to the transmitting end via a further fiber-optical channel in order to command a changeover from one signal source to another.