Protocol and bit rate independent test system

• US 6,430,715 B1
• Filed: 03/23/2000
• Issued: 08/06/2002
• Est. Priority Date: 09/17/1999
• Status: Expired due to Fees

• Current Assignee: Digital Lightwave Incorporated
• Original Assignee: Digital Lightwave Incorporated
• Inventors: Gardner, Douglas J., Myers, Kenneth T.
• Primary Examiner(s): Decady, Albert
• Assistant Examiner(s): Torres, Joseph D.
• Application Number:
  US09/533,582
• Time in Patent Office: 866 Days
• Field of Search: 714/704, 714/708, 714/709, 375/321, 375/224, 359/110, 359/180
• US Class Current: 714/704
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0293 Optical channel protection
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• CPC Class Codes: H04L 7/00 Arrangements for synchronising receiver with transmitter synchronisation of generators of electric oscillations or pulses H03L7/00

Abstract

A protocol and bit rate independent test system for detecting bit errors on a digital communications channel regardless of format or rate, comprising a receiver for receiving an input, a clock recovery unit, a threshold sampling circuit for providing at least two threshold detectors for respective two sampling points including at least one static sampling point positioned proximate to the center of an eye pattern and at least one dynamic sampling point, the output of which are sampled by the recovered clock and if the signal passes between the thresholds, an error signal is generated and counted.

Claims

1. A protocol and bit rate independent test system including means for detecting bit errors on a digital communications channel regardless of format or rate, comprising in combination:

a receiver for receiving an input;

a clock recovery unit;

a threshold sampling circuit for providing at least two threshold detectors for respective two sampling points including at least one static sampling point positioned proximate to the center of an eye pattern and at least one dynamic sampling point, the output of which are sampled by the recovered clock and if the signal passes between the thresholds, an error signal is generated and counted.

2. The protocol and bit rate independent test system as set forth in claim 1, comprising a plurality of the dynamic sampling points and wherein the dynamic sampling points are movable in an array about an eye measurement.

3. The protocol and bit rate independent test system as set forth in claim 2, wherein the array comprises a linear array.

4. The protocol and bit rate independent test system as set forth in claim 2, wherein the array comprises a two-dimensional array.

5. The protocol and bit rate independent test system as set forth in claim 1, wherein said clock recovery unit comprises a variable rate clock recovery unit.

6. The protocol and bit rate independent test system as set forth in claim 1, wherein said receiver comprises an optical receiver and wherein said input comprises an optical input.

7. The protocol and bit rate independent test system as set forth in claim 6, wherein the optical receiver is PIN photodiode based.

8. The protocol and bit rate independent test system as set forth in claim 6, wherein the optical receiver is avalanche photodiode based.

9. The protocol and bit rate independent test system as set forth in claim 1, further including frequency measurement including a high speed prescaler which drives a counter and provides a timebase to a protection switch detection circuit.

10. The protocol and bit rate independent test system as set forth in claim 9, further including a protection switch detection circuit for comparing the counted errors in a given timebase period with a programmable threshold and upon exceeding the threshold, for producing an active protection switch output.

11. The protocol and bit rate independent test system as set forth in claim 1, wherein said threshold sampling circuit comprises a variable threshold sampling circuit.

12. The protocol and bit rate independent test system as set forth in claim 1, further including an error detect and Q measurement processing logic for reading the error signals.

13. The protocol and bit rate independent test system as set forth in claim 1, further including a jitter measurement processing logic.

14. A protocol and bit rate independent test system method for detecting bit errors on a digital communications channel regardless of format or rate, comprising in combination:

receiving an input signal;

recovering the clock from the input signal;

sampling at least two sampling thresholds from the input signal for respective two sampling points including at least one static sampling point positioned proximate to the center of an eye pattern and at least one dynamic sampling point; and

producing an error signal if the input signal passes between the thresholds.

15. The method as set forth in claim 14, comprising a plurality of the dynamic sampling points and wherein the dynamic sampling points are movable in an array about an eye measurement.

16. The method as set forth in claim 15, wherein the array comprises a linear array.

17. The method as set forth in claim 15, wherein the array comprises a two-dimensional array.

18. The method as set forth in claim 14, wherein the step of recovering the clock from the input signal comprises the step of recovering the clock from the input signal at a variable rate.

19. The method as set forth in claim 14, wherein the step of receiving a signal input comprises the step of receiving an optical signal input.

20. The method as set forth in claim 19, wherein the step of receiving the optical signal input employs an optical receiver.

21. The method as set forth in claim 20, wherein the optical receiver is PIN photodiode based.

22. The method as set forth in claim 21, wherein the optical receiver is avalanche photodiode based.

23. The method as set forth in claim 14, further including the step of measuring the bit rate to provide a timebase to a protection switch detection circuit.

24. The method as set forth in claim 14, wherein the step of sampling at least two sampling thresholds from the input signal comprises the step of sampling at least two variable sampling thresholds.

25. The method as set forth in claim 14, further including the step of reading the error signals.

26. The method as set forth in claim 25, wherein the step of reading the error signals employs an error detect and Q measurement processing logic.

27. The method as set forth in claim 14, further including the step of comparing the counted errors in a given timebase period with a programmable threshold and upon exceeding the threshold, producing an active protection switch output.

28. The method as set forth in claim 14, further including the step of measuring jitter.