Nokia 4A0-205 Exam - Topic 6 Question 60 Discussion

Actual exam question for Nokia's 4A0-205 exam

Question #: 60
Topic #: 6

What is the definition of OSNR?

AThe 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.

BThe OSNR is the ratio between the optical output signal power and the optical input signal power of the device being analyzed.

CThe OSNR is defined as the ratio between the average optical signal power and the average optical noise power over a specific spectral bandwidth.

DThe OSNR is defined as the ratio between the optical signal power (including noise) and the optical noise power over a specific spectral bandwidth.

Show Suggested Answer

Suggested Answer: 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. This is also known as the signal-to-noise ratio (SNR), and it is a measure of how much signal is present in the optical signal compared to the noise, usually expressed in decibels (dB).

by Yolande at Jan 05, 2026, 05:16 AM

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Desirae

11 days ago

Hmm, I thought OSNR stood for "Optical Silly Noise Ratio"?

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Beula

16 days ago

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.

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Beckie

21 days ago

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.

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Barb

27 days ago

I thought OSNR was about the ratio of signal to noise, but I’m confused about the specifics of bandwidth in the definitions.

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Melda

1 month ago

I feel like option D sounds right because it mentions the optical signal power including noise, but I can't recall the exact details.

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Ulysses

1 month ago

I remember practicing a question similar to this, and I think it had to do with the average power of the signal and noise.

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Elin

1 month ago

I think OSNR stands for Optical Signal-to-Noise Ratio, but I'm not sure which option correctly defines it.

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Lashandra

2 months ago

Wait, I think the key here is the "specific spectral bandwidth" part. The OSNR is the ratio of the average optical signal power to the average optical noise power over a certain bandwidth. That means option C is the correct definition.

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Iluminada

2 months ago

I've got this! The OSNR is the ratio of the output signal power to the input signal power of a device, so I'm going to go with option B.

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Shawn

2 months ago

Okay, I remember learning about OSNR in class. I'm pretty sure it's the ratio of the transmitted optical power to the received optical power, including both signal and noise, over a specific distance. So I'll select option A.

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Ettie

2 months ago

Hmm, I'm a bit confused on this one. I know OSNR has something to do with the signal-to-noise ratio, but I'm not sure which of these options is the exact definition. I'll have to think it through carefully.

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Paris

2 months ago

I think the definition of OSNR is the ratio between the optical signal power and the optical noise power over a specific bandwidth, so I'll go with option D.

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