Nokia Certified Network Professional – IP/MPLS Services — Question 29

What is the definition of OSNR?

Answer options

• A. The OSNR is defined as the ratio between the transmitted optical power and the received optical power over 1 km of fiber, including both signal and optical noise.
• B. The OSNR is the ratio between the optical output signal power and the optical input signal power of the device being analyzed.
• C. The OSNR is defined as the ratio between the average optical signal power and the average optical noise power over a specific spectral bandwidth.
• D. The OSNR is defined as the ratio between the optical signal power (including noise) and the optical noise power over a specific spectral bandwidth.

Correct answer: C

Explanation

The correct answer is C because it accurately defines OSNR as the ratio of average optical signal power to average optical noise power over a specific bandwidth. Option A is incorrect as it refers to a distance of 1 km of fiber, which does not align with the general definition of OSNR. Option B is not correct because it focuses on input and output signal power rather than the noise aspect, and Option D, while closer to the correct definition, does not specify 'average' for the signal and noise power, which is important in the context of OSNR.