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

Background of the invention

The invention relates to a transceiver 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 computer board in which the electrical interface is suitable for providing a transceiver module with user data to be used. sent to the optical transmission line and for delivery of a computer board with the reading of user data from the optical transmission line, and further comprising monitoring means for monitoring the optical transmission line.

This transceiver module is known from European Patent Application No. 04 291 995.1, scheduled to be published after the submission of this application.

Optical networks are used to transfer digital data. The optical network includes optical transceivers that are connected by optical transmission lines, in particular optical fibers.

Commonly optical transceivers are implemented with optical transceiver modules. The optical transceiver module is a device for processing electrical signals that transfer user data received through the electrical interface to optical signals that are sent to the optical interface (where an optical transmission line is attached), and for converting optical signals received through the optical interface into electrical signals . Usable data, no matter where contained in the received electrical signals or contained in the received optical signals, are transferred, without any analysis of the utility data, such as error analysis or error correction in the transceiver module.

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The transceiver module is typically connected to a computer board, where the data to be sent and the received data are processed and analyzed.

Unfortunately, optical fibers may have defects. A defect can cause data loss. For this reason, the status of the optical fiber in the optical network must be monitored. The well-known monitoring method is the OTDR method (OTDR time domain optical reflectometry). In this method, short optical pulses are sent to the optical fiber through which they propagate. At places of defects, such as sharp bends inside the optical fiber, the light of the optical pulse is particularly strongly backscattered. The time between sending the pulse and receiving the peak value of the backscattered light indicates the location of the defect.

It is known from the aforementioned European patent application to integrate equipment for OTDR measurement, in particular a coupler with a tap, photodiode and OTDR signal output, into an optical transceiver module. The ODTR signal is forwarded, without any analysis, to the error detection means of the external transceiver module via the OTDR signal output.

In order to investigate the state of optical fiber, including prior art, a large amount of data must be transmitted through the OTDR signal output. In addition, the installation of the optical transceiver module requires a data interface connection and an ODTR signal output.

EP 1 524 781 A1 describes a transceiver module with a transmitter and a receiver for transmitting data, and with ODTR measuring means for checking the optical link status. Measuring means ODTR uses the same transmitter as for data transmission.

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US 6,549,310 B1 describes a diagnostic system for optical links for use with an optical transmitter system. The multiplexer is connected from the upstream side to the laser controller, so that the test signal can be introduced into the optical fiber. The photodiode, usually used to set the laser, is used to record the backscattered test signal.

Object of the invention

The object of the present invention is to provide an optical transceiver module that is simpler for installation and with which only a small amount of control data must be transmitted.

Brief description of the invention

The object is achieved, according to the invention, by the transceiver module initially described as characterized in that the transceiver module comprises analyzing means for processing the measurement data provided by the monitoring means in a statistical manner, and that the analyzing means are connected to the electrical interface to provide processed measurement data to the electrical interface.

The inventive transceiver module can reduce the amount of control data to be processed. In the analyzing means, the measured data is processed statistically and only the results of this statistical processing are expelled as processed measurement data.

Typically, the processing includes averaging. The resulting processed measurement data is typically a much smaller amount of data than the raw measurement data. The analyzing means can also be designed to provide clear information on whether the monitored fiber is ready for action or not, or to provide other coarse status information

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EP 1 763 158 B1 optical transmission line. This can be done by comparing measurement data or processed measurement data with reference values ​​and / or tolerance ranges. Means of indicating "ready for operation or not", such as a light emitting diode, may be provided in the transmitter module housing.

In addition, processed measurement data is not sent to a separate control output or interface, but the processed measurement data is also supplied to the electrical interface using for user data. Since the amount of control data to be processed is rather small according to the invention, there is no significant loss of performance in the transmission of user data at the electrical interface. A separate control output or interface is not required. This means that the installation of the transceiver module and the external design of the inventive transceiver module as a whole is simplified.

Note that if you are considering usage data, there is no or transactional processing in the inventive transceiver module. The analyzing agent only processes control data by checking the condition of the optical fiber. In particular, the user information is only forwarded by the inventive transceiver module. For operational data, the transceiver module is only an electro-optical processing interface.

The transceiver module of the invention typically has a length of about 5 to 8 cm and a diameter of about 1.5 to 2.5 cm. Typically representatives of the transceiver devices (i.e. transceiver modules) that can be modified and used in accordance with the invention are the modules SFF (Small FormFactor), SFP (Small Form-_Factor Pluggable) or GBIC (Gigabit Interface Converter).

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In the inventive transceiver module, improved access to control results, i.e. processed measurement data, is available.

In a preferred embodiment of the invention, the transceiver module, the electrical interface comprises a bi-directional electric bus, in particular a bus I²C. Such a bus is an improved means of data transfer. With this electric bus, control parameters and control data can easily be exchanged between the transceiver module and the computer board.

In addition, a variant in which the analyzing means comprise an analog-to-digital processing unit (= A / D) and a processor is preferred. The A / D processing unit typically receives analog measurement data from a photodiode and provides digital measurement data to the processor that performs the processing. The processor is typically implemented as an integrated circuit or chip.

An advantageous additional development of this variant is characterized in that the processor includes input memory, processing memory, in particular suitable for averaging operations and output memory. Such a design is suitable for obtaining real-time measurement data.

In another preferred embodiment of the transceiver module, the monitoring means are designed to perform time domain optical reflectometry (= OTDR). OTDR is an improved method for fiber optic monitoring.

Also within the scope of the invention is a transceiver system comprising the inventive transceiver module as described above, and a computer board in which the transceiver module is connected to the computer board only via an electrical interface. The transceiver module is easy to install and replace in the event of a defect. Computer board

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EP 1 763 158 B1 may, in connection with the invention, be designed for an additional process or analysis of processed measurement data provided by a transceiver module.

It is within the scope of the invention to provide access to measurement data from monitoring of an optical transmission line coupled to the inventive optical transceiver module as described above, in which the monitoring means monitor the optical transmission line, characterized in that the measurement data provided by the monitoring means are still processed in the optical transceiver module in a statistical manner, thus generating processed measurement data, and that only processed measurement data is excreted via the electrical interface of the optical transceiver module. The method provides a transceiver module with additional functionality that maintains data capacity. Control data becomes easier and faster to access. Data processing is simpler because only one electrical interface is used for all data (i.e. for user data and control data).

In a preferred variant of the inventive method, when processing measurement data of the monitoring means, the frequency of the line transfer is decimated. This decimation is achieved, according to the invention, by averaging. That is, ten lines each with a single pulse are added to generate the average line. The line is a graph graphically showing the amplitude of backscattered light as a function of time (or distance).

Another preferred variant of the inventive method is characterized in that the electrical interface is also used to provide control parameters to the optical transceiver module. Then, control parameters can be

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EP 1 763 158 B1 selected and changed as required, without the need for additional electrical interfaces.

A preferred variant of the inventive method is characterized in that the electrical interface comprises a bi-directional electrical bus, and in that part of the available frequency of the electric bus is allocated to provide control parameters to the optical transceiver module and / or to process measurement data. Allocation simplifies data transfer.

Additional advantages will be visible from the description and the attached drawings. The features mentioned earlier and later can be used in conjunction with the invention either individually or collectively in any combination. The mentioned variants do not present an exhaustive picture, but rather are exemplary for the description of the invention.

Drawings

The invention is illustrated in the drawing.

Fig. 1 schematically illustrates the inventive transceiver module installed on a computer board;

Fig. 2 schematically shows the analyzing means of the transceiver module of Fig. 1.

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

The invention proposes to process measurement data still within the optical transceiver module in a statistical manner, and to provide only processed measurement data from outside. Processed measurement data is available from the same electrical interface that supports user data. In particular, for this purpose, the electric bus can be integrated in the electric interface.

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Additional analyzing means are integrated in the transceiver module. These analyzing means allow determining (or helping to determine) the characteristics, i.e. physical parameters, of the optical transmission line connected to the module. Determining the characteristics can be the optical data channel needed for transmission. only to the transceiver. carried out for each individual.

The analyzing means may contain all or part of the equipment to determine the optical characteristics of the line

In general, the analysis means are suitable for coarse analysis, in particular for deciding whether fiber optic is ready for action or not. In the case where the analyzing means only contain part of the equipment needed to determine (at least some) optical fiber characteristics, the additional equipment is arranged at the computer board holding the transceiver module. Then the interaction between the computer board and the transceiver module takes place, and their interaction is optimized to allow smoothing of the optical network.

In order to carry out a control measurement, it will be necessary to exchange parameters defining the measurement procedure and the type of measurements, which depend on the system requirements:

(pulse width, modulation amplitude, ..);

- measurement period, number of averages, number of samples;

- control signal (e.g. measurement initialization);

- alarm signal.

The invention proposes the use of an existing electrical bus to transfer these parameters or data, i.e. by allocating a portion of the available frequency band on an existing digital data bus.

- physical parameters of the frequency range

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Fig. 1 schematically shows the inventive optical transceiver module 1 enabling control functions, here in the case of ODTR measurements. The transceiver module 1 includes an electrical interface 2, an optical interface 3 where an optical transmission line (not shown) is attached. The electrical interface is connected to the computer board 4. Via the electrical interface 2, the input user data 5 is provided to the laser mechanism and control unit 6, which in turn is connected to the laser diode 7. The laser diode 7 emits light in a particular channel with a wavelength λ1. It passes through the 8 WDM coupler and the optical coupler with the tap 9 and into the optical interface 3. On the other hand, the light with the wavelength λ 2 is received in the optical interface 3. It passes through the coupler with tap 9 and is reflected at the WDM 8 coupler from the photodiode & TIA unit (transimpedance amplifier) ​​(data) 10. The photodiode & TIA unit signal (data) 10 is fed to LIA (amplitude limiter) & LOS detection unit ( signal losses) 11 and supplied to the electrical interface 2 as output user data 12. To monitor the fiber optic status, the laser mechanism and control unit 6 may also emit test pulses with wavelength λ1 to check the channel operation at that wavelength. Part of this light with wavelength λ1 is scattered backwards in the optical transmission line and is therefore present at the optical interface 3. This light is reflected at the coupler with tap 9 to the photodiode & TIA unit (OTDR) 13, and the signal of the photodiode & TIA unit (OTDR) 13 is fed to the analyzing means 14. Basically, the coupler with tap 9 and the photodiode & TIA unit (OTDR) 13, together with the light emitting and controlling components, represent the monitoring means in the transceiver unit 1. Inside the analyzing means 14, the received signal is analyzed

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Backscattered light, taking into account the original test pulse with wavelength λ1 and its emission time (in fact, the analyzing means control the emission of the test pulse). The result of this analysis is the processed measurement data that is provided to the electrical interface 2.

The electrical interface 2 has a bi-directional function ₂ electric control bus, here bus 15 I²C operating at clock cycle frequency typically 100 or ₂

400 kHz. Through this bus 15²C, main unit 16 of the computer board control bus 4 is provided with processed measurement data. The control bus master unit 16 may provide analyzing means 14 with control parameters for monitoring the process. Bus 15 I²C is furthermore intended for transporting diagnostic information, such as transceiver temperature or laser current, to a computer board 4.

In Fig. 2, the interior of the analysis means 14 is described in greater detail, which can also be considered as a processor / control means. The 21 ODTR signal provided by the photodiode & TIA (ODTR) unit (denoted 13 in Figure 1) is fed to the A / D processing unit 22. This unit successively provides digital measurement data 23, which is delivered to processor 24. Processor 24 generates processed measurement data 25; the processed measurement data is supplied to the electrical interface, i.e. to its control bus (not shown in figure 2). Processor 24 includes input memory 26, processing memory 27 and output memory 28.

The processor unit 24 allows decimation of the frequency of the line transfer to adapt to the rapid collection of measurement data (i.e. ten lines per second) to the properties of the control bus, which typically

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EP 1 763 158 B1 has a low data transfer rate (i.e. one line per second).

The frequency of OTDR data collection is determined by the protocol used, i.e. by beam transmission operation systems (GPON, connection between ground station and satellite) for the OTDR single pulse technique, or - by the intermediate frequency filter sweep speed for the sinusoidal wave sweep technique.

The frequency of reading processed measurement data from the transceiver module to the computer board is determined by the serial frequency of the I clock cycle²C, which is generally used for the transport of diagnostic information (transceiver temperature), laser current, etc.).

In the example of Fig. 2, a 21 ODTR signal with a line of 5000 samples 10 kByte / line was used. Digital measurement data 23 is read from a width of 10 lines per second to an input memory 26, which has a capacity of 10 kbyte / line. The processor memory 27 averages the inbound data with a capacity of 20 kbyte / line. After the desired number of averages (i.e. after 10,000 averages), the resulting data are read in the output memory with a throughput of 10 kbyte / line, from where the data is sent to the computer board by using the I bus²C. Main bus²C works at 100 kBit / s clock cycle frequency.

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