Device for detecting polarization mode dispersion

1. A device for detecting polarization mode dispersion of an optical data signal by evaluating an electrical baseband signal, comprising:

a polarization mode dispersion compensator;

at least one multiplier which calculates a value of an autocorrelation function of the baseband signal by multiplication of a value of the baseband signal by a delayable value of the baseband signal, wherein the value of the autocorrelation function indicates the presence of polarization mode dispersion;

an averaging device for averaging the calculated value of the autocorrelation function; and

a regulator for controlling the PMD compensator using the autocorrelation function.

2. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 1 , further comprising:

a delay line with taps, wherein taps with different delays are respectively connected to inputs of the at least one multiplier.

3. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 2 , wherein two delay lines are provided through which, in a region in which the two delay lines exhibit a mutual assignment via the inputs of the at least one multiplier, the baseband signal runs in opposite directions such that the delays occurring between adjacent multipliers are added to form a delay difference between the adjacent multipliers.

4. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 2 , wherein two delay lines are provided which, in a region in which the two delay lines exhibit an assignment via the inputs of the at least one multiplier, are traversed in a same direction such that the delays occurring between adjacent multipliers are subtracted from one another to form a delay difference between the adjacent multipliers.

5. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 2 , wherein delays that occur are equidistant with a constant delay difference.

6. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 2 , wherein a delay difference is at least approximately equal to a symbol duration of the baseband signal.

7. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 1 , further comprising:

a plurality of delay lines of different lengths to whose ends inputs of multipliers are connected.

8. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 7 , further comprising:

a detour line provided in one of the delay lines.

9. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 7 , further comprising:

a buffer amplifier in one of the delay lines.

10. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 1 , wherein the regulator at least approximately maximizes a non-delayed value of the autocorrelation function and adjusts values of the autocorrelation function that are delayed by at least one symbol duration at least approximately to the value zero.

11. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 1 , further comprising:

a measuring arrangement for measuring a bit error rate in the event of one of an intentionally impaired reception signal and a changed threshold value of a second decision stage, an error signal of the measuring arrangement further controlling the polarization mode dispersion compensator via the regulator.

12. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 11 , wherein the regulator is used additionally for adaptively setting the values of the autocorrelation function that are sought.

13. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 1 , wherein the multiplier is an EXOR gate.

14. A device for detecting polarization mode dispersion of an optical data signal as claimed in claim 1 , where the multiplier is a Gilbert multiplier.

15. A device for detecting polarization mode dispersion of an optical data signal by evaluating an electrical baseband signal, comprising:

at least one multiplier which calculates a value of an autocorrelation function of the baseband signal by multiplication of a value of the baseband signal by a delayable value of the baseband signal, wherein the value of the autocorrelation function indicates the presence of polarization mode dispersion;

a delay line with taps, wherein taps with different delays are respectively connected to inputs of the at least one multiplier, and wherein a delay difference is at least approximately equal to a symbol duration of the baseband signal; and

an averaging device for averaging the calculated value of the autocorrelation function.

16. A device for detecting polarization mode dispersion of an optical data signal by evaluating an electrical baseband signal, comprising:

a polarization mode dispersion compensator;

a regulator, communicatively coupled to the polarization mode dispersion compensator

at least one multiplier which calculates a value of an autocorrelation function of the baseband signal by multiplication of a value of the baseband signal by a delayable value of the baseband signal, wherein the value of the autocorrelation function indicates the presence of polarization mode dispersion;

an averaging device for averaging the calculated value of the autocorrelation function; and

a measuring arrangement for measuring a bit error rate in the event of one of an intentionally impaired reception signal and a changed threshold value of a second decision stage, wherein an error signal of the measuring arrangement is used by the regulator to control the polarization mode dispersion compensator.