Abstract:
An optical time-domain reflectometer, OTDR, apparatus is configured to measure a backscattered trace of a fiber link under test (FLUT). The OTDR apparatus includes at least one photo diode adapted to detect an optical signal reflected from points along the fiber link under test in response to an optical test signal generated by a laser of the OTDR apparatus and supplied to the fiber link under test. The reflected optical test signal is attenuated or amplified automatically such that the power of the optical signal received by the photodiode is limited to a predetermined power range.
Abstract:
A method for generating a tone signal (TS) having a tone frequency, f, wherein the method comprises the following steps: supplying (S1) a binary bit stream (BBS) having a mark pattern with a supply bit rate, BR, to a signal filter unit; and filtering (S2) the supplied binary bit stream (BBS) by said signal filter unit to generate the tone signal (TS), wherein the mark pattern of the binary bit stream (BBS) supplied to said signal filter unit is adapted to minimize a ratio of the supply bit rate, BR, to the tone frequency, f, of the generated tone signal (TS).
Abstract:
A method for creating an optical binary digital transmit signal to be supplied to an optical transmission link including: operating an optical transmitter in such a state that mode hopping occurs between a predefined first and a predefined second optical mode of the optical transmitter if a binary digital modulation signal is supplied to the optical transmitter and creating a modulated optical output signal of the optical transmitter corresponding to the binary digital modulation signal supplied to the optical transmitter. The modulated optical output signal is optically filtered in such a way that at least a portion of the optical power spectrum of the modulated optical output signal caused by a selected one of the first and second optical modes is suppressed or at least substantially attenuated.
Abstract:
The invention relates to a method for creating a control channel in an optical transmission signal, wherein the optical transmission signal (SDS,i, SUS,i) includes an optical carrier frequency component, a higher frequency modulation component carrying user information to be transported from a first end to a second end of an optical transmission link and a lower frequency modulation component carrying control information, the higher frequency modulation component realizing a user channel and the lower frequency modulation component realizing the control channel, and wherein the lower frequency modulation component is created by amplitude modulation. According to the invention, the lower frequency modulation component includes a binary digital pilot tone signal component which corresponds to a pilot tone signal having a predetermined pilot tone frequency (fi).
Abstract:
The invention relates to an optical WDM transmission network including at least one optical line terminal, a remote node and a plurality of optical network units. The at least one optical line terminal is connected to the optical remote node via an optical WDM path. Each optical network unit is connected to the optical remote node via an optical distribution path.
Abstract:
The invention relates to an optical WDM transmission network including at least one optical line terminal, a remote node and a plurality of optical network units. The at least one optical line terminal is connected to the optical remote node via an optical WDM path. Each optical network unit is connected to the optical remote node via an optical distribution path.
Abstract:
A method for transmitting a binary digital transmit signal over an optical transmission link includes creating a differential optical duobinary signal, supplying the differential optical duobinary signal to a first end of the optical transmission link, transmitting the differential optical duobinary signal to a second end of the optical transmission link, and receiving the differential optical duobinary signal as a receive signal at the second end of the optical transmission link. The differential optical duobinary signal may be created by pre-coding the binary digital transmit signal having a given bit interval (T) in two pre-coding steps each with a signal delay of a single bit interval or in a single pre-coding step with a signal delay of twice the bit interval. In each case the pre-coding applies a non-XOR or equivalent operation.
Abstract:
The invention relates to a protected optical single-fiber WDM system. A first (3) and a second (5) head-end terminal and at least one optical add/drop filter device (11) are connected to form a chain-like transmission path, each of the first and second head-end terminals (3, 5) being connected, at a WDM port (3a, 5a), through a single optical fiber (13) to a western (11a) or an eastern WDM port (11d) of an adjacent one of the optical add/drop filter devices (11), respectively, and each of the optical add/drop filter devices (11) being connected, at an eastern or western WDM port (11d, 11a), to a western or eastern WDM port (11a, 11d) of an adjacent one of the optical add/drop filter devices (11), respectively. At least one tail-end terminal (9) is connected to each optical add/drop filter device (11), wherein a first (9a) and a second (9b) channel port of the respective add/drop tail-end terminal (9) is connected to a dedicated first (11b) and second (11c) channel port of the optical add/drop filter device (11) through a respective optical fiber (15,17). The head-end terminals (3, 5), the optical add/drop filter devices (11) and the tail-end terminals (9) are adapted to selectively or simultaneously establish a bidirectional communication between each tail-end terminal (9) and the first and second head-end terminal (3, 5), wherein each tail-end terminal (9) bidirectionally communicates through its first channel port (9a) with the first head-end terminal (3) and bidirectionally communicates through its second channel port (9b) with the second head-end terminal (5), one of these communication paths serving as a working communication path and the other of these communication paths serving as a protection path, wherein for the communication between each of the tail-end terminals (9) and the first and second head-end terminal (3, 5), respectively, dedicated optical channel signals lying in a first wavelength band and a second wavelength band are used for each transmission direction, the first and second wavelength band revealing no overlap and the optical channel signals in each wavelength band forming, in each transmission direction in the chain-like transmission path, respective optical WDM signals.