Optical communications
AssigneeBritish Telecommunications public limited company
InventorsKevin SMITH, Yu ZHOU
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Abstract
The present invention provides a method of indirectly determining the optical signal-noise ratio of an optical fibre communications link. In a test environment, the relationship between OSNR and pre-FEC BER (forward error-corrected bit error rate) is determined for a particular type of optical transponder. When a transponder of that type is connected to an optical communications link then the pre-FEC BER can be measured and the OSNR inferred from the pre-determined OSNR-BER relationship. The OSNR value can then be used to select a transponder modulation format or other transmission parameters.
Claims12
A method of determining the performance of an optical communications link, the method comprising the steps of:
- i) determining an OSNR (optical signal to noise ratio) to BER (bit error rate) relationship for an optical transponder;
- ii) connecting the optical transponder to an optical communications link;
- iii) measuring the bit error rate of the optical communications link;
- and
- iv) determining the OSNR for the optical communications link in accordance with the relationship determined in step i) and the measurement made in step iii).
Dependencies are inferred from the claim text.