WO2005062512A1 - Method and arrangement for the insertion of filling signals - Google Patents

Abstract

Filling signal rates (Flambda2, Flambda3) are generated in the event of an omission of a full received WDM -signal (WDM1) or also for individual data signals (lambda2, lambda3) by mounting the channel amplifiers (7,9), together with frequency-dependent elements such as a wavelength multiplier (10) or a wavelength demultiplexer (12), as oscillators.

Description

 Method and arrangement for inserting fill signals

The invention relates to a method and an arrangement for inserting fill signals when channels of a received WDM signal fail.

Today, the transmission of optical signals via glass fibers takes place largely in wavelength division multiplexing (WDM / DWDM). In systems with optical amplifiers, the sudden loss of input signals or even entire signal bands leads to a strong influence on the remaining signals. Despite the gain regulators operating quickly, particularly in the case of several cascaded amplifier sections, level changes in the remaining signals which are not tolerable occur and which not only cause signal interference but can also lead to failure of the entire transmission path or damage to receiving devices.

Numerous methods and arrangements are known in which, regardless of the number of input signals, an attempt is made to keep the power constant per active channel. One of these options is to replace the failed signals with signals from so-called filling lasers. A disadvantage of this method is the high cost of implementation, since a separate fill reader must be available for each data signal and therefore for each 1.

The object of this invention is to provide cost-effective options for generating fill signals.

This object is achieved by the independent method claim 1 and the independent arrangement claim 5. The method according to the invention can be used particularly advantageously wherever the WDM signal 1 is divided into individual data signals (channels) which are conducted via separate amplifiers. By returning their output signals via filters with bandpass characteristics, oscillators can be implemented with little additional effort.

The invention can be used particularly advantageously in add-drop devices in which channel amplifiers are provided for level adjustment anyway, or in a channel-specific regenerator device. So only a little additional effort is required.

It is advantageous if the replacement signals are the same

Level can be set that the data signals have. Switching between replacement signals and data signals can then take place smoothly without level fluctuations occurring at the amplifier input. The output level of the substitute signals is determined by the amplifier control and thus corresponds to that of the data signals.

The method according to the invention can be used both in the event of failure of individual signals and in the event of failure of the complete WDM received signal.

Embodiments of the invention are explained in more detail with reference to figures.

Show it

Figure 1 shows an add-drop device with equivalent signal circuit in the event of failure of the WDM receive signal and

Figure 2 shows an add-drop device for inserting individual fill signals.

FIG. 1 shows an add-drop device with an upstream amplifier 1, to which a received wavelength Multiplex signal WDM1 is supplied. The amplified WDM signal passes via a measuring splitter 2 and a controllable attenuator (VOA) 4 to a wavelength de-ultiplexer 4 (which can also be implemented by individual components such as splitters and filters). There the WDM signal is divided into individual data signals (channels) λl to λ4. For example, the data signals λl and λ4 are output as drop signals SDR (dropped) and the signals λ2 and λ3 are fed to a channel amplifier 7 and 9 via a coupler 6 and 8, respectively. The channel amplifiers have the task of raising the data signals to the same predetermined levels. The amplified signals are combined with add signals to be coupled in, of which only one add signal SAD is designated, in a wavelength division multiplexer 10 (which can also be implemented by individual components such as splitters and filters) and as WDM signal WDM2 output.

The output WDM signal WDM2 is divided by a second measuring splitter 11 into a (larger) signal component, which is emitted via the signal output 15, and a second (smaller) signal component, which as a feedback signal RS has a second wavelength demultiplexer 12 is fed, where it is divided into the data signals corresponding channel feedback signals Rλ2, Rλ3, the input via the adjusting elements such as switches or attenuators (VOA) 13 or 14 and the combiners 6 to 8 (coupler or filter elements) Amplifiers 7 and 9 are supplied. In the case of undisturbed operation, the feedback path through the attenuators 13 and 14 is interrupted.

If the data signals λ2, λ3 fail, however, the feedback path is released. Each of these amplifiers 7 and 9 then forms an oscillator due to the feedback with the wavelength-selective elements, which oscillates at the wavelength of the previous data signal. A control and monitoring device 5 here checks the complete received WDM signal WDM1, from which a monitoring signal US is branched off by a first measuring splitter 2. If the complete WDM signal WDM1 fails, the feedback paths for the amplifiers 7 and 9 are released and the reception path is interrupted by the attenuator 3 (or a switch) in order to suppress interfering signals, as in the case of an interrupted fiber by the optical amplifier 1 or several cascaded amplifiers can be generated. If the level at the amplifier output can be kept low, then the attenuator can be omitted.

When the fill signals Fλ2 and Fλ3 are generated, the input levels of the amplifiers 7 and 9 are set to the level of the data signals by the attenuators 13 and 14. The

Output levels of the channel amplifiers are kept constant by controls, not shown. Corresponding equivalent circuits can also be provided for the add signals SAD.

The monitoring and control device 5 can also be designed such that it monitors the data signals in the individual transmission channels. For this purpose, however, an additional wavelength demultiplexer is required, which divides the WDM measurement signal into individual data signals.

The add-drop device shown in FIG. 2 contains a monitoring and control device 51, which monitors the data signals individually and uses the existing filter elements for this purpose. The output of the optical amplifier 1 is now connected directly to the wavelength demultiplexer 4. A measurement splitter 21 and 22, which branch off channel measurement signals Mλ1 and Mλ2, are connected downstream at two of its outputs. The measuring splitter 21 is followed in series by an optical switch 311 (or an attenuator), the coupler 6 and the channel amplifier 7, the measuring splitter 22 the switch: r 32, the coupler 8 and the channel amplifier 9. The outputs cier Amplifiers 7 and 9 are connected to inputs of a modified wavelength multiplexer 101 and are each guided here via a channel filter 16 or 17, of which a channel feedback signal Rλ1 and Rλ, 2 are branched off via further measuring splitters 111, 112 and is traced back to an input of a channel amplifier in the event of a fault.

This embodiment of the add-drop device allows both individual replacement of individual data signals with individual fill signals and replacement of the entire received WDM signal. The control and monitoring device 51 checks each channel level individually and only when the channel power drops to a value below a reference value is the filling signal generated as a replacement. This has the advantage that the transmission channel is retained, albeit with poorer properties. A higher reference value can be set for monitoring purposes.

Since the substitute signals are continuous signals (which usually represent the logical 1), their level can also be reduced, for example, to half the target power by identifying and maintaining the power balance by intervening in the control of the channel amplifiers 7 and 9 becomes. Just like in the arrangement. Figure 1 can also include the add signals in the equivalent circuit.

The time constants of the amplifier control and fill signal generation are to be coordinated.

Claims

claims 1. Method for inserting filler signals in the event of failure of data signals (λ2, λ3) of a received optical WDM signal (WDMl), characterized in that the received WDM signal (WDMl) is divided into optical data signals (λl-λ4) that data signals (λ2, λ3) to be performed are routed via channel amplifiers (7, 9) and, if necessary, combined with add signals (ADS) to form a WDM signal (WDM2) to be transmitted, that a monitoring and control device (5, 51 ) monitors the received WDM signal (WDMl) and / or the data signals (λl- λ4) and, if the received WDM signal fails and / or if the data signals (λ2, λ3) fail, fill signals (Fλ2, Fλ3) instead of these signals the same wavelength is generated by feedback of the channel amplifiers (7, 9) via frequency-dependent elements (10, 12; 101). 2. The method according to claim l, v characterized in that the fill signals (Fλ2, Fλ3) are only generated when the power of a data signal (λl-λ4) or the received WDM signal (WDMl) falls below a reference value. 3. The method according to claim 1 or 2, characterized in that in the event of failure of the received WDM signal (WDM1) or of data channels (λ2, λ3) connections between the inputs of the: channel amplifier (7,9) and signals interrupted or attenuated; become. 4. The method according to claim 1 or 3, characterized in that the level of the filling signal (λ2, λ3) at the input of the channel amplifier (7,9) corresponding to the level of the Da to be replaced tensignals (λ2, λ3) or is set according to a predetermined level. 5. The method according to claim 1, characterized in that in the event of a fault, add signals (ADS) and / or drop signals (DRS) are replaced by fill signals. 6. Arrangement for inserting fill signals (Fλ2, Fλ3) in the event of data signal failure of an optical WDM signal (WDMl), characterized in that a wavelength demultiplexer (4) converts the received WDM signal (WDMl) into individual optical data signals (λl -λ4) divides that data signals (λ2, λ3) to be carried out which are output at the outputs of the wavelength demultiplexer (4) are each conducted via an optical coupler (6, 8) and a channel amplifier (7, 9), so that the outputs of the channel amplifiers ( 7,9) are connected to the inputs of a wavelength division multiplexer (10), so that for each channel amplifier (7,9) a feedback via filter elements (10, 12, 101) can be switched by adjusting elements (13, 14), so that it vibrates on the wavelength of a data signal (λ2, λ3) and generates the fill signal (Fλ2 _f Fλ3), and that a monitoring and control device (5; 51) is provided which receives the WDM signal (WDM1) and / or the data signal e (λl-λ4) are supplied, which switches through the existing data signals (λ2, λ3) or, in the case of failed data signals, activates the feedback for generating the fill signals (Fλ2, Fλ3). 7. Arrangement according to claim 6, characterized in that controllable attenuators or switches (13, 14) are arranged in the feedback path as setting elements (13, 14). 8. Arrangement according to claim 6 or 7, characterized in that controllable attenuators (3) or switches (31, 32) are arranged in the signal path of the received WDM signal (WDM1) or in the signal paths of the data signals (λ2, λ3). 9. Arrangement according to claim 6 or 7, characterized in that the wavelength multiplexer (101) has channel filters (16, 17) with downstream measuring splitters (111, 112), the measuring outputs of which are led out. 10. Arrangement according to one of claims 6 to 9, characterized in that it is combined with an add-drop device.