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:
Jun. 06, 1995
Filed:
Feb. 22, 1993
Ian Hardcastle, Harlow, GB;
Northern Telecom Limited, Montreal, CA;
Abstract
An optical transmission system utilizing at a transmitter (100) continuous phase frequency shift keyed modulation of a laser (14) and a coherent heterodyne receiver (200) therefor, the system including at the transmitter means for imposing (18,12) a low frequency modulation on the transmitter optical power and frequency deviation and at the receiver means for extracting (28) from the receiver AGC control signal a replica of the low frequency modulation, means for demodulating (32) the modulated frequency deviation of the received optical signal synchronously with respect to the extracted low frequency signal, means for deriving (34) from the demodulated signal an error signal and a control system responsive to the error signal to control the receiver local oscillator (22) frequency.