# Power margin of a fiber-optic system

• MattH150197
In summary, the conversation discusses a question about calculating the power margin of a fiber optics system using given information such as transmitter power, connector loss, attenuation, total length, and receiver threshold. The solution involves using the power budget and power margin equations, resulting in a margin of 12.5dB. There is confusion over a given answer of 9.5dB, which does not match the calculated result.
MattH150197

## Homework Statement

Im going over some revision for fibre optics and I've come across an example question to calculate the power margin of the system with the following info is given:
transmitter power = -10dBm
Connector loss = 1.5dB
Attenuation = 3dB/Km
Total length= 2KM

## Homework Equations

Power budget = Pt - Pr
Power Margin = PB - Total losses

## The Attempt at a Solution

PB = -10 - - 30 = 20
PM = 20 - ((3*2) + 1.5)) = 13.5dB
However it says the answer is 9.5dB, i didnt write the formulas wrong did i when i was making notes or can you see where I've gone wrong anywhere?

Last edited by a moderator:
If you have written the problem correctly and completely, then I agree with your result and suspect that the "answer" is wrong.

MattH150197
MattH150197 said:
PM = 20 - ((3*2) + 1.5)) = 13.5dB
Should be 12.5 dB. Unfortunately still not 9.5dB.

MattH150197
Oops right, I didn’t subtract that properly in my head!

MattH150197
I'd like to know how the given answer was obtained if you ever find out.

MattH150197
1. Oops! Sorry yeah I meant 12.5, I really have no idea where 9.5dB has come from and it was really frustrating why I was getting different. So thanks for clearing it up guys!

## 1. What is the power margin of a fiber-optic system?

The power margin of a fiber-optic system is the difference between the minimum required optical power and the maximum power that can be transmitted through the system without causing errors or signal degradation.

## 2. Why is the power margin important in a fiber-optic system?

The power margin is important because it ensures that the system has enough power to operate reliably and account for any fluctuations or losses in the optical signal. It also allows for future upgrades or changes in the system without causing disruptions.

## 3. How is the power margin calculated in a fiber-optic system?

The power margin is typically calculated by measuring the difference between the received optical power and the minimum required power for the system to function properly. This is often referred to as the received power margin.

## 4. What factors can affect the power margin of a fiber-optic system?

The power margin of a fiber-optic system can be affected by various factors such as the type and quality of the fiber, the distance of the transmission, the type and quality of the connectors and splices, and any external environmental conditions that may cause signal loss or interference.

## 5. How can the power margin be optimized in a fiber-optic system?

The power margin can be optimized in a fiber-optic system by using high-quality components, regularly cleaning and maintaining the system, ensuring proper installation and alignment of connectors and splices, and choosing the appropriate power levels for the system based on the distance and type of fiber used.

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