Optical transceiver module for monitoring an optical fiber and method for making available measuring data from monitoring an optical fiber

ES 2 298 967 T3

DESCRIPTION

Optical transmitter-receiver module to monitor an optical fiber and method to make the measurement data from the monitoring of an optical fiber available.

Background of the invention

The invention relates to a transmitter-receiver module for an optical data network, comprising an optical interface for connection to an optical transmission line and an electrical interface for connection to a central panel, wherein the electrical interface is suitable for providing the transceiver module with payload data to be sent on the optical transmission line and for providing the center panel with payload data extracted from the optical transmission line, and further comprising monitoring means for monitoring the optical transmission line.

Said transmitter-receiver module is known from European patent application 04 291 995.1 scheduled to be published after the filing of this application.

Optical networks are used to transmit digital data. An optical network comprises optical receiver transmitters that are linked by optical transmission lines, in particular optical fibers.

It is common to make optical transceivers with optical transceiver modules. An optical transceiver module is a device for converting electrical signals that carry payload data, received at an electrical interface, into optical signals, which are sent over an optical interface (where an optical transmission line has been attached), and to convert optical signals, received at the optical interface, into electrical signals. Payload data, regardless of whether it is contained in received electrical signals or contained in received optical signals, is only passed on, without performing any payload data analysis such as error analysis or error correction within the transceiver module. .

The transceiver module is typically linked to a central panel, where the data to be sent and the data received are processed and analyzed.

Unfortunately, the optical fibers could become defective. A defect could cause data loss. For this reason, the status of an optical fiber in an optical network must be monitored. A well-known monitoring method is optical time domain reflectometry (hereinafter otdr). In this method, a short optical pulse is sent over an optical fiber, through which the pulse is propagated. At defect locations, such as a sharp bend within the optical fiber, the light from the optical pulse in particular experiences strong backscatter. The time between sending the pulse and receiving a backscattered light crest indicates the location of the defect.

From the aforementioned European patent application, it is known to integrate equipment for an otdr measurement, in particular a lead coupler, a photodiode and an otdr signal output, to an optical transmitter-receiver module. The otdr signal is passed, without any signal analysis, to a fault detection means installed externally to the transceiver module via the otdr signal output.

In order to know the state of the optical fiber, in this state of the art, a large amount of data must be transferred on the otdr signal output. In addition, the installation of the optical transceiver module requires linking a data interface and an otdr signal output.

Document ep 1 524 781 a1 describes a transceiver module with a transmitter and a receiver for data transfer, and with OTDR measurement means for checking the status of an optical link. OTDR measurement means use the same transmitter as the data transfer.

US 6,549,310 b1 describes a diagnostic system for optical links for use with a transmitter optical system. A multiplexer is connected upstream to a laser driver, so that a test signal can be inserted into an optical fiber. A photodiode, usually used to adjust the laser, is used to record the backscattered test signal.

Object of the invention

The object of the invention is to provide an optical transceiver module that is easier to install and with which only a small amount of monitoring data needs to be transferred.

Brief description of the invention

This object is achieved, according to the invention, by means of a transmitter-receiver module that responds to the introduction of the principle of this specification, characterized in that the transmitter-receiver module comprises

ES 2 298 967 T3 is an analysis means for processing measurement data provided by the monitoring means in a statistical way, and in that the analysis means are connected to the electrical interface to provide processed measurement data to the electrical interface.

With the transceiver module, the amount of monitoring data to be downloaded as output can be reduced. With the analysis means, the measured data is processed in a statistical way, and only the results of this statistical processing are output as processed measurement data. The resulting processed measurement data typically constitutes a much smaller amount of data than the untreated measurement data. The analysis means could also be designed to provide explicit information on whether or not the monitored optical fiber is ready to operate, or to provide other approximate information on the status of the optical transmission line. This could be done by comparing the measurement data or the processed measurement data with reference values ​​and / or tolerance intervals. A "ready to go or not" indicative means, such as a light emitting diode, could be provided in the transceiver module housing.

Additionally, the processed measurement data is not sent on a separate monitoring output or interface, but said processed measurement data is supplied to the electrical interface also used for payload data. Since the amount of monitoring data to be output is rather small according to the invention, there is no significant loss in the transfer capacity of the payload data at the electrical interface. A separate monitor output or interface is dispensed with. This means that the installation of the transceiver module is simplified, as well as the external design as a whole of the transceiver module of the invention.

Note that, as far as payload data is concerned, no signal analysis or statistical treatment is performed within the transceiver module of the invention. The analysis means only treat the monitoring data by checking the state of the optical fiber. In particular, the payload information is passed only in the transceiver module of the invention. For payload data, the transceiver module is just an electrical-optical conversion interface.

A transceiver module according to the invention typically has a length of about 5 to 8 cm and a diameter of about 1.5 to 2.5 cm. Typical representations of transmitter-receiver devices (i.e. transmitter-receiver modules) that can be modified and used in accordance with the invention are small form factor (hereinafter SFF), small form factor plug-in (in hereinafter SFP), and Gigabit capable interface converter (hereinafter GBIC).

With the transmitter-receiver module of the invention, you have improved access to the monitoring results, that is, to the processed measurement data.

In a preferred embodiment of the transceiver module of the invention, the electronic interface comprises a bidirectionally operative electrical bus, in particular a PC bus (or busbar). This bus is an approved means of transferring data. With this electrical bus, the monitoring parameters as well as the monitoring data could be easily exchanged between the transceiver module and the central panel.

Furthermore, an embodiment is preferred in which the analysis means comprise an analog-digital conversion unit (hereinafter A / D) and a processing unit. The A / D conversion unit typically receives analog measurement data from a photodiode and supplies digital measurement data to the processing unit, which performs data processing. The processing unit has typically been realized as an integrated circuit or a chip.

A further preferred evolution of this embodiment is characterized in that the processing unit comprises an input memory, a processing memory, in particular suitable for an averaging operation, and an output memory. This design is well suited for real-time measurement data extraction.

In another preferred embodiment of the transceiver module of the invention, the monitoring means have been designed to perform optical time domain reflectometry (OTDR. OTDR is an approved method for monitoring an optical fiber.

Also within the scope of the invention is a transmitter-receiver arrangement comprising a transmitter-receiver module as described above, and a central panel, wherein the transmitter-receiver module is connected to the central panel only through the electrical interface. The transceiver module is easily installed and replaced, for example, in the event of a defect. The central panel could be designed, in accordance with the invention, to further process or analyze the processed measurement data provided by the transceiver module.

Also within the scope of the invention is a method of making available measurement data from monitoring an optical transmission line coupled to an optical transceiver module of the present invention as described above, wherein a monitoring means monitors the optical transmission line, characterized in that the measurement data provided by the monitoring means is still processed within the optical transmitter-receiver module in a statistical way, thereby generating measured measurement data.

ES 2 298 967 T3 two, and because only the processed measurement data is downloaded as output by means of an electrical interface of the optical transmitter-receiver module. The method provides the transceiver module with additional functionality, which saves data transfer capacity and the monitoring data is made available in a simpler and faster way. Data management is easier, since only one electrical interface is used for all data (ie payload data and monitoring data).

In an advantageous variant of the method of the invention, during the processing of the measurement data of the monitoring means, a trace transfer frequency is decimated. This decimating operation is obtained, according to the invention, by establishing the average. For example, ten traces each are added from a single pulse to generate the averaged trace. A trace is a diagram that represents the amplitude of the backscattered light as a function of time (or distance).

Another advantageous variant of the method of the invention is characterized in that the electrical interface is also used to provide monitoring parameters to the optical transceiver module. The monitoring parameters could then be chosen and changed as required, without the need for more electrical interfaces.

A preferred variant of the method of the invention is characterized in that the electrical interface comprises an electrical bus that operates bidirectionally, and in that a part of the range of available frequencies of the electrical bus is assigned to the provision of monitoring parameters to the optical transmitter-receiver module and / or or to the processed measurement data. Mapping simplifies data transfer.

Additional advantages can be deduced from the description and accompanying drawings. The features mentioned both above and below can be used in accordance with the invention, either individually or collectively, in any combination. The mentioned embodiments are not to be understood as an exhaustive enumeration, but rather are exemplary for the description of the invention.

Drawings

The invention has been represented in the drawings, in which:

Figure 1 schematically presents a transmitter-receiver module of the invention installed in a central panel;

Figure 2 schematically shows the analysis means of the transmitter-receiver module of Figure 1.

The invention relates to an optical transceiver module comprising monitoring means for monitoring an optical transmission line, and a method for making available data collected by the monitoring means of the transceiver module.

The invention proposes to treat the measurement data still within the transceiver module in an analytical way, and to make only the processed measurement data available externally. The processed measurement data is made available with the same electrical interface that manages the payload data. In particular, an electrical bus could be integrated into the electrical interface for this purpose.

In the transmitter-receiver module, additional means of analysis are integrated. These analysis means allow the determination of (or aid in the determination of) characteristics, that is, physical parameters, of the optical transmission line linked to the transceiver module. Characteristics determination could be done individually for each optical data channel.

The analysis means could comprise all or a part of the equipment necessary for determining the characteristics of the optical transmission line. In general, the analysis means per se is only suitable for approximate analysis, in particular for deciding whether or not an optical fiber is ready for operation. In the case that the analysis means comprise only a part of the equipment necessary for the determination of (at least some of) the characteristics of the optical fiber), additional equipment is available such as a central panel that transports the transmitter module -receiver. An interaction then takes place between the central panel and the transceiver module, and their interaction is optimized in order to enable smooth operation of the optical network.

To perform the monitoring measurements, it will be necessary to exchange parameters that define the measurement procedure, as well as the class of measurements, which depend on the system requirements:

- physical parameters (pulse width, modulation amplitude, frequency range ...);

- measurement time period, number of mean values, number of samples;

- control signals (eg measurement initialization);

- alarm signals.

ES 2 298 967 T3

The invention proposes the use of the current electrical bus, for the transport of these data parameters, for example, by assigning a part of the range of available frequencies within the current digital data bus.

Figure 1 schematically presents an optical transmitter-receiver module 1 of the invention that enables the monitoring functions, here in the case of OTDR measurements The transmitter-receiver module 1 comprises an electrical interface 2 and an optical interface 3 in which it is fixed an optical transmission line (not shown). The electrical interface is connected to a central panel 4.

Through the electrical interface 2, input payload data 5 is supplied to a laser drive and control unit 6 which in turn is connected to a laser diode 7. The laser diode 7 emits on a particular channel a light at a wavelength λ1, which passes through a wavelength diffusion multiplexing coupler 8 (hereinafter WDM) and an optical tap coupler 9 and to the optical interface 3. On the other hand, light of a wavelength Λ2 is received at the optical interface 3, which passes through the lead coupler 9 and is reflected in the WDM coupler 8 onto a photodiode and transimpedance amplifier unit 10 ( data). The signal from the photodiode and transimpedance amplifier unit 10 (data) is fed to a limiting amplifier detection unit 11 (hereinafter TIA and loss of signal (hereinafter LOS) and supplied to the electrical interface 2 as data 12 payload output. In order to monitor the state of the optical fiber, the laser driving and control unit 6 could also emit test pulses at wavelength λ 1 to check the channel working at the wavelength. A part of this light with wavelength λ 1 is backscattered within the optical transmission line, and therefore is present at the optical interface 3. The light is reflected from the lead coupler 9 onto a photodiode and TIA (OTDR) unit 13, and the signal from the photodiode and TIA unit 13 (= OTDR) is fed to an analysis means 14. Basically , the lead coupler 9 and the photodiode and TIA (OTDR) unit 13 together with the light emitting components and their control, represent a monitoring means within the transmitter-receiver unit 1. Within the analysis means 14, the signal of the received backscattered light is analyzed, taking into account the original test pulse of wavelength λ 1 and its emission time (actually, the analysis means controls the emission of the pulse of proof). The result of this analysis is the processed measurement data, which is supplied to electrical interface 2.

The electrical interface 2 comprises an electrical control bus that operates bi-directionally, in this case a PC bus 15 that operates at a clock frequency of typically 100 or 400 kHz. By means of this PC bus 15, a main bus control unit 16 of the central panel 4 is provided with the processed measurement data. The main bus control unit 16 could also provide the analysis means 14 with monitoring parameters for the monitoring process. Furthermore, the PC bus 15 is intended for the transport of diagnostic information, such as the temperature of the transceiver or the intensity of the laser current, to the central panel 4.

In Figure 2, the interior of the analysis means 14 is described in more detail, which can also be considered as a processor controller means.

An OTDR signal 21 provided by the photodiode and TIA unit (OTDR) (reference numeral 13 in FIG. 1) is fed to the A / D conversion unit 22. This unit in turn provides the digital measurement data 23 that is input to a processing unit 24. The processing unit 24 generates processed measurement data 25, and the processed measurement data 25 is fed to the electrical interface, that is, to its control bus (which is not shown in Figure 2). The processing unit 24 comprises an input memory 26, a processing memory 27 and an output memory 28.

The processing unit 24 allows the trace transfer rate to be decimated in order to adapt a rapid acquisition of the measurement data (for example, ten traces per second) to the properties of the control bus which typically has a low speed. data transfer rate (for example, one trace per second).

The OTDR data acquisition frequency is given by:

- the protocol used, for example by pulse train mode operating system (Gigabit capable passive optical network, hereinafter GPCON, uplink) for single pulse OTDR technique, or

- using the IF filter tuning speed for the swept sine wave technique.

The frequency of extracting the processed measurement data from the transmitter-receiver module to the central panel as information is given by the serial clock frequency of the PC bus, which is generally used for the transport of diagnostic information (transmitter temperature- receiver, laser current intensity, etc).

In the example of Figure 2, OTDR signal 21 is used with a trace with 5,000 samples and 10 kByte / trace The digital measurement data 23 is read with 10 traces per second in the input memory 26, which has a capacity 10 kByte / trace. The processor memory 27 fulfills the averaging of the input data with a capacity of 20 kByte / trace. After a desired number of averages (for example after 10,000 averages) the resulting data is read into the output memory with a capacity of 10 kByte / trace, from where the data is transferred to the central panel using the PC bus. . The PC bus operates at a clock rate of 100 kbits / s.