DE3019264A1 - Splicing multicore optical cables - using manipulator to align ends with laser pulse reflectometer for accurate determn. of joint. - Google Patents

Abstract

The splicing of multi-core optical cables is achieved by means of an impulse reflectometer situated at the measuring end of the cable, the opposite end of which, (splice and), is to be connected with another multicore cable, core for core, e.g. by welding. A manipulator is provided at the measuring end, for arranging the cable ends in V-shaped grooves, side by side, and preparing these ends, for connection to the reflectometer (RM), which contains a laser transceiver, and must be coupled to the conductors individually one after the other, via a lens. This is carried out by the manipulator, which is movable in three coordinate directions. Each conductor is aligned to a max., the relevant coordinates being stored. A second phase of the procedure entails establishing the time situation of at least two scanning impulses and storing these, so that in the third measuring phase, the measured and stored coordinate values of the first manipulator are called up and adjusted for the individual light conductor. This enables the splice to be accurately positioned with the help of a second manipulator at the splice position, and allows the whole procedure to be carried out by one person.

Description

Method of splicing multi-core optical cables

The invention relates to a method for splicing multiple wires optical cable by measuring the splice loss using a pulse reflectometer, the inputting a pulse in the optical waveguide and an optical transmitter the reflection reproducing display device.

From "Philips Telecommunication Review", Volume 37, No. 4, Sept. 1979, Pages 241 to 249 a measuring device for optical cables is known, which means of a laser transmitter works, its pulse-shaped transmission signal in the respective Optical fiber is coupled. On the receiving end, i.e. at the far end of the cable a corresponding evaluation device connected, which is a display device to display the measurement result, so it works as a pulse reflectometer. In the case of a representation corresponding to the transit time of echo signals, any Show disturbances e.g. by splice points on a screen and the determine the corresponding damping values.

When splicing multi-core optical cables, special ones arise Problems due to the fact that in many cases, e.g. when cables have already been laid, the end of the cable is in a different place than the actual splice point. Since the measurement of the Quality. however, the splice can only be made from the far end of the cable for measuring the splice points normally both at the measuring end and at the Splicers each require an operator who can carry out the necessary manipulations the Adjusting devices makes and also the measured values to the respective other Operator transmits in a suitable manner.

The present invention, which relates to a method of the opening paragraph referred to, the object is based on a measuring method of the initially to further educate the named type in such a way that the splicing can be carried out by only one person is and, moreover, the corresponding measurement processes can be carried out relatively quickly can. According to the invention this is achieved by means of the at the measuring end of the optical cable connected pulse reflectometer in a first measuring process each optical waveguide of the cable to the maximum by means of a first manipulator set and the associated coordinate values are stored that in a second measuring process, the time position of at least two sampling pulses established and stored, of which the first immediately before and the second immediately after the splice is that in a third measuring process from the end of the splice one after the other the measured and stored coordinate values of the first manipulator are called up and can be set for the individual optical waveguides, then with a second manipulator at the splice point is used to optimize the respective splice, and that the one received at the end of the measurement for the individual positioning processes Measured values are transmitted to the end of the splice and displayed there 4 In this way it is possible to carry out the necessary adjustments for the splicing of optical fibers to be carried out with a single operator, because those to be done at the end of the measurement Adjustment processes determined as part of the first measurement process and then stored will. These setting values determined and saved in this way can then be used from splice end from being called one after the other, with only a corresponding transmission is necessary for the control commands. This transmission line can be provided in the form of a separate measuring cable (extension cable). One Another advantageous solution is that in each case one wire to be spliced optical cable itself is used for feedback.

Developments of the invention are given in the subclaims.

The invention is explained in more detail below with reference to drawings. 1 shows in a block diagram an exemplary embodiment of an arrangement for Implementation of the method according to the invention, FIG. 2 shows the structure of an optical Soft, Fig. 3 the backscatter curve of an optical waveguide with a splice, 4 shows the remote control device present at the splice end.

In Fig. 1, a multi-core optical cable is denoted by LWK1, the one at the left end (splice end) using a suitable splicing device (e.g. by welding) wire by wire connected to another optical cable LWKO shall be. At the measuring end of the optical cable LWK1 facing away from the splice point a manipulator MA is provided, e.g. in n parallel V-grooves V1 to Vn die n Fiber optic fibers of the optical cable LWK1 side by side or in one other predetermined configuration has arranged and their ends for connection to an optical pulse reflectometer containing a laser transmitter and receiver (OTDR), - which is designated with RM, - provides - in detail this must e.g. via a lens OL successively to the connection points V1 to Vn of the n optical waveguide fibers of Fiber optic cable LWK1.

This is done by means of the manipulator MA, which works in three coordinate directions x, y, z is movable and is set e.g. via three corresponding servomotors.

In particular, it is done in a predetermined order, for example proceed in such a way that first the connection V1 is made to the first wire of the cable LWK1 becomes, including a certain combination of coordinates xl, yl and z1 of the manipulator MA is required. The pulse reflectometer RM is about the manipulator MA so connected that to the oscilloscope OG, which corresponds to FIG. 3, the backscatter signal and echo signal.

reproduces, reached at A a largest possible amplitude value. That means that the transition to the optical waveguide fiber no. 1 with the lowest possible Damping takes place. The maximum obtained for the respective optical waveguide Positions xl, y1, z1 are entered into a computer RE and stored there. In Proceed in the same way for the remaining wires up to Vn.

In a second measuring process, as shown in FIG. 3, the position set by at least two sampling pulses a and b. The sampling pulse lies here a seen from the end of the measurement shortly before the splice point and the sampling pulse b shortly after the splice. It is advisable to provide a third sampling pulse c, which determines the zero line (reference value) and after emde of the optical cable LWKO lies. The amplitude value C belongs to the sampling pulse and the amplitude value belongs to the sampling value b B and for sample a the amplitude value A.

These sampling pulses a, b, c, which appear as corresponding signals the oscilloscope OG are displayed, and can be timed accordingly are displaceable or are displaced by the scanner AT (sample and hold- Circuit) from also given in the computer RE and recorded there in their temporal position. For a certain cable LWK1 - it is usually sufficient to enter the values a, b and c once because they can be used for all fiber optic cables of the LWK1 cable.

After these setting processes have been carried out, they are therefore in the computer RE the positioning values xl, y1, z1 to xn, yn, zn of the n-optical waveguide fibers stored together with the corresponding time values for the sampling pulses a, b, c before. In this way, all the necessary measured values are obtained which, on the one hand, are used at the end of the measurement Coupling of the pulse reflector RA to the respective optical fiber is required as well as the scanning pulses a, b, c, which are used to measure the splice are necessary.

After performing these preparatory measurements at the end of the measurement the actual splicing process, which takes place at the end of the splice, can be carried out. For this purpose, a transmitter SE is provided at the measuring end, which is connected to the computer RE and whose output is led to an optical switch WE. This switch has-one Output led via the receiver EM to the computer RE. The computer RE is on the output side connected to the manipulator MA.

There is a corresponding measuring line between the measuring end and the splice end provided, which is shown in the present example as a separate line ML. But it is also possible with the lines to be spliced or one of the fibers of the optical cable LWK1 itself. In this case a special one is to be produced Line connection similar to the additional line ML is not required. However then the last splicing process to be carried out must be carried out without supervision, because there is no longer any measuring line available for this. In many cases, however, are especially with optical Cable some extra fibers as a reserve provided so that the optical to be spliced without any major difficulties Cable LWK itself used with a fiber as a return line for the measurement process can be.

The structural units provided at the splice end are by adding marked with the letter S. To the connection line ML is initially a Switch WES switched on, the output of which is led to a receiver EMS while its input is connected to an SES transmitter. Details of one possible Structure for both the WE switch at the measuring end and for the WES switch at the end of the splice are shown in Fig. 2, where left in a schematic representation of a connection for the transmitter SE or SES is drawn. The electrical signals present there are converted into optical signals by a light-emitting diode LED and a lens L1 fed.

Some of the optical transmission signals pass through a 50% mirror SP Via a further lens L2 to the measuring line ML and from there to the respective other turnout circuit. The signals coming from the connecting line ML are via the lens L2 and the mirror SP and another lens L3 of a photodiode FOD fed and from there as electrical signals to the respective receiver EM supplied at the end of the measurement or EMS at the end of the splice.

If the line ML is designed as an electrical line, are to provide electrical switch circuits constructed in an analogous manner.

With the receiver EMS at the end of the splice there is a display device AZS connected, which essentially the existing on the oscilloscope OG of the measuring end Information about the amplitude values A and B and / or about the attenuation values of the Splice point of Fig. 3 again- gives. It is therefore for the operator at the end of the splice by looking at the display device AZS easily possible, to continuously record the quality of the respective splice connection and the effect to watch for any changes.

A transmitter SES is also connected to the switch WES, which transmits the transmits signals coming from a remote control device FBS to the end of the measurement.

Furthermore, the actual splicing device VBS is provided, which e.g. be designed as a welding device or as a mechanical clamping device can. At the end of the splice there is also a manipulator MAS: its coordinate values are denoted by x ', y' and z '.

In detail, the splicing process is carried out at the end of the splice proceeded as follows: Using the remote control device FBS controls the Operator via the transmitter SES, the switch WES, the connecting line ML, the switch WE and the receiver EM, the computer RE, which is stored according to the Roordinate values xl, yi, zl for fiber no. 1, the positioning of the optical waveguide No. 1 performs.

This means that the measuring device for measuring the fiber is at the end of the measurement No. 1 prepared, with the setting to the maximum at the end of the measurement already carried out is.

At the end of the measurement, the receiver EM the pulse reflectometer RM-activated and sends pulse-shaped measuring signals to the fiber optic cable LWK1. Depending on the quality of the connection point between the optical fiber no. 1 of the fiber optic cable LWKO and fiber optic no. 1 of the optical Cable LWK1 is the amplitude jump at the splice according to FIG. 3 of a certain Size. The coordinate values e.g. x'1, y'1 and z'1 for the first fiber are now so long in the manipulator MAS at the end of the splice changed until this jump i.e.

the difference between the amplitude values A and B according to FIG. 3, if possible becomes small.

If necessary, signal A can first be activated and held for as long (for After adjustment) the manipulator MA can be changed again until A becomes a maximum. This process is only necessary if the originally set with xl, yl, z1 and -stored value for A has changed in the meantime. Then the signal B called up, i.e. the measurement is carried out after the splice point and for as long as the Manipulator MUS changes until signal B also has a maximum. if these two maxima, i.e. the maximum of A and the maximum of B for the fiber No. 1 are reached, the splicing process can be carried out, e.g. B. by gluing, Welding joints or the like.

It is possible after the actual splicing process has been carried out still to determine the splice loss, i.e. the difference between A and B according to Fig. 3 and register in the computer RE. This can be done using the remote control FBS a corresponding control signal after the actual splicing process has been carried out are emitted and the splice attenuation is then determined by means of the pulse reflectometer RM determined in the computer RE and recorded by appropriate registration devices or displayed.

In an analogous way is now for the remaining optical waveguide fibers No. 2 to n, from the end of the splice, the respective maximum of B and, if applicable, of A (if required), i.e. the splice loss minimized and then the splicing process carried out.

At the end of the process, all of the optical waveguides 1 to n des optical cable LWK1 connected to the individual fibers of the optical cable LWKO with the lowest possible attenuation.

The method described above can be used in a relatively simple manner Quickly and reliably splice multi-core cables with just one operator Carry out fiber optic cables, the equipment expense being relatively small can be held.

The setting of the manipulator MAS takes place in the present exemplary embodiment by hand. It is, however, possible for an automatic maximization to take place here as well allow.

The MAS manipulator can, for example, only be used in the form of a simple adjustment device be designed for an adhesive splice (with V-grooves).

Fig. 4 shows the control panel for the remote control device FBS and the display device AZS. The respective one appears in a display field AF1 Amplitude value of A or B, depending on whether key TA (for signal A) or the button TB (for the signal B) is pressed. Using the TRM key, the pulse reflectometer RM can be switched on or off. In a preselection field VW are through appropriate (buttons not shown here) the individual fibers 1 to n are set.

By means of the preselection field VW, the corresponding Values xl, yl, z1 to xn, yn, zn of the n-fibers of the optical cable are provided.

In the present example it is also assumed that with the remote control device FBS, the manipulator MA at the end of the measurement can also be operated.

Adjustment devices Tx, Ty, Tz as well as Tx *, Ty * and Tz * are required for this. provided, the former being an increase in the respective value x, y and z of the manipulator MA and the latter cause a reduction in size.

All that is required for the operator at the end of the splice is enter the necessary control commands on the control panel shown in FIG and thereby perform the splicing process. A second display field AF2 can after the completion of the respective splicing process for a specific optical waveguide the splice loss (in this case 0.2dB) can be displayed.

The splice loss can be determined from the sampled values A, B and C obtained evaluate according to the following formula: αSP = 5 log ##### - αF. l1.

Here, SP = splice attenuation (in dB) A, B, C = measured values at the points in time a, b, c = = average fiber attenuation without splice (in dB / km) 11 = spacing of the sampling pulses a and b (in km, 11 0.1 km corresponds to about 0.1 / us).

The mean attenuation of the optical waveguide X F can either be in be determined in a separate measuring process, e.g. before starting the splicing work. More expedient and simpler is another solution, with the before and after the splice next to two additional samples A * and B * are obtained from samples A and B, so that there are two measured values in front of the splice point and two measured values / after the before splice point. From the difference of the values A and A * or B and B * can be, there the intermediate distance is known from the time difference, the mean Calculate the attenuation of the respective fiber optic cable.

The calculation of the individual attenuation values and the storage e.g. of the value F is expediently carried out by means of the computer RE-.

The work of the operator can advantageously be simplified by that in the control panel according to FIG. 4, the amplitude values A and B are linearly converted into corresponding ones Frequency values are converted, i.e. between the respective frequency and the respective There is a direct relationship with the amplitude value. These frequencies can e.g. can be made audible via the connections KH1 and KH2 using headphones and the operator can know from the frequency difference between the measurement at Amplitude value A and the measurement at amplitude value B can be seen directly how large the splice loss is.

4 Figures 11 claims

Claims (11)

Claims 1. A method for splicing multi-core optical cables by measuring the splice loss using a pulse reflectometer, the inputting a pulse in the optical waveguide and an optical transmitter the reflection reproducing display device, d u r c h e k e n n z e i c h n e t that by means of the connected to the measuring end of the optical cable (LWK1) Pulse reflectometer (RM) in a first measuring process of each optical waveguide of the Cable (LWK1) set to maximum by means of a first manipulator (MA) and the associated coordinate values (x, y, z) are stored that in a-second Measuring process set the timing of at least two sampling pulses and is stored, of which the first (a) immediately before, and the second immediately after the splice is that in a third measuring process from the end of the splice one after the other the measured and stored coordinate values (x, y, z) of the first manipulator (MA) can be called up and set for the individual optical fibers, whereby then with a second manipulator (MAS) at the splice point of the respective Splice is optimized, and that at the end of the measurement, in each case for the individual positioning processes The measured values obtained are transferred to the end of the splice and displayed there4 2. Procedure according to claim -1, d a d u r c h g e -k e n n n z e i c h n e t that another Sampling pulse (c) is set, which is after the cable end and as a reference value is used. 3. The method according to any one of the preceding claims, d a d u r c h e k e n n n z e i c-h n e t, - that before and after the splice at least each two sampling pulses are provided and that from the difference of the associated amplitude values the mean attenuation of the respective optical fiber is calculated and saved will. 4. The method according to any one of claims 1 to 3, d a -d u r c h g e it is not indicated that the mean attenuation of the optical waveguide is separated is measured and stored. 5. The method according to any one of the preceding claims, d a d u r c h e k e n n n e i c h n e t that a readjustment of the am First measured and stored coordinate values (x, y, z) are carried out will. 6. The method according to any one of the preceding claims, d a d u r c it should be noted that the connection between the splice end and the measuring end made via an additional, preferably optical connection line (ML) will. 7. The method according to any one of claims 1 to 5, d a -d u r c h g e it is not indicated that the connection between the splice end and the measuring end is over one of the. change of the optical cable (LWK1) is made. 8. The method according to any one of the preceding claims, d a d u r c h e k e k e n n n n e i c h n e t that on the display device provided at the end of the splice (AZS) the sampling value obtained with the first (a) and second (b) sampling pulse (A, B) is displayed (in AF1). 9. The method according to any one of the preceding claims, d a d u r c h e k e k e n n n n e i c h n e t that on the display device provided at the end of the splice (AZS) the value of the splice loss (in AF2) is shown. 10. The method according to any one of the preceding claims, d a d u r c h e k e n n n z e i c h n e.t that with the remote control device provided at the splice end Preselection fields (VW) are provided for the individual optical fibers. 11. The method according to any one of the preceding claims, d a d u r c it should be noted that the amplitude values (A, B) are present at the end of the splice and after the splice point, amplitude-proportional frequencies are converted and be made audible.