US 7,321,730 B2
Method and apparatus for the transmission fault detection in an access network
Kent Felske, Kanata (Canada); Richard Brand, Palo Alto, Calif. (US); and Eric Bernier, Nepean (Canada)
Assigned to Nortel Networks Limited, St. Laurent (Canada)
Filed on Jun. 23, 2003, as Appl. No. 10/600,713.
Claims priority of provisional application 60/445837, filed on Feb. 06, 2003.
Prior Publication US 2004/0156635 A1, Aug. 12, 2004
Int. Cl. H04J 14/00 (2006.01); H04B 10/08 (2006.01); H04B 10/14 (2006.01)
U.S. Cl. 398—71  [398/32; 398/58; 398/10; 398/100; 398/99; 398/76; 398/66; 398/198] 5 Claims
OG exemplary drawing
 
1. A transmitter for an optical network unit (ONU) for transmitting data over a return data channel of a passive optical network in accordance with a predefined time-sharing protocol, the transmitter comprising:
a laser driver for driving a laser of the transmitter to generate an optical carrier;
a modulation sub-system for modulating data onto the optical carrier generated by the laser; and
a secondary modulation sub-system for impressing an ONU identifier onto the optical carrier, the ONU identifier serving to identify the ONU to a network monitor that monitors the return data channel, the secondary modulation sub-system comprising a tone source for supplying a tone that serves as the ONU identifier to a tone modulator to modulate the ONU identifier onto the optical carrier; and
a switch for selectively switching the tone to the tone modulator so that the tone modulator does not impress the ONU identifier onto the optical carrier during a timeslot allocated to the ONU.