system margin

[FAYIQA NAQSHBANDI]

HELLO EVERYONE..
I had a query about setting or knowing the the system margin.. As we know that the purpose of the system margin is to allocate a certain amount of power to additional sources of power penalty that may develop during the system lifetime…
System margin is an important factor in calculating the power budget of a system…can anyone please tell me where and how we set or come to know about it..?
Thanking everyone in advance.
regards
Fayiqa

[Aabid Baba]

Hello fayiqa,
As we know the purpose of power budget is to ensure that enough power reaches the receiver to maintain reliable performance during the entire system lifetime. The minimum average power required by the receiver is the receiver sensitivity. Both receiver sensitivity and transmitted power play an important role in calculating the power power and in addition to that “system margin” as well. I am posting a link where it has been discussed in detail about different parameters to be taken into consideration. I hope it helps you.

System Design – Power Budget

Regards

[FAYIQA NAQSHBANDI]

HI AABID
thank you for replying.. i went through the link you provided and it was very helpful indeed but i still have a confusion regarding the system margin..if you check it has calculated the total Channel Loss = System Margin + Receiver Sensitivity + Transmitter power which he assumes to be
30 – 3 + 0 = 27 dB ; where he takes -30 dBm as receiver sensitivity and output power of -3 dBm and system margin = 0
My question is how does he presume system margin to be 0 and how and where does he set it…
thanks and regards

[Yasir Saifullah]

Hello Fayiqa,
System margin is set to ensure that small variation in the system operating parameters do not result in an unacceptable decrease in system performance. I have attached two snapshots. One contain formula to calculate power budge and the other contains an example for this calculations.
hope this information will help you out.
Regards,

[FAYIQA NAQSHBANDI]

HI YASIR
First of all thank you so much for your efforts..The formulae you have shared i have already come across these..i am doubtful about the value of system margin…i mean how do we set it in optisystem or how we know it is +4.1 in the case you have shared..is there a definite formula to calculate the system margin or it is us who choose it..please can u tell me a bit more..i wud be grateful..
Thanks and regards

[SAHIL SINGH]

hi all..

it was a nice query and also came across setting same parameters in my design..it helped me a lot but i still wonder what is an appropriate value for system margin..can we calculate it by some formula or anythng like that..

Regards

Sahil Singh

[Manoj Kumar]

Hello fayiqa,
As we know the purpose of power budget is to ensure that enough power reaches the receiver to maintain reliable performance during the entire system lifetime. The minimum average power required by the receiver is the receiver sensitivity. Both receiver sensitivity and transmitted power play an important role in calculating the power power and in addition to that “system margin” as well. I am posting a link where it has been discussed in detail about different parameters to be taken into consideration. I hope it helps you.

System Design – Power Budget

Regards

[Rajguru M. Mohan]

Hi,
The difference between power levels of two i.e Any optical transmission system requires a defined range of optical receiver input power for proper operation. In practice, the received power must be higher than the minimum level and lower than the maximum level is called is the optical margin.
A design margin of 6dB is common in telecom systems, although the installed system may achieve a better value, since “worst case” conditions are of course infrequent. The design margin of some high speed LAN systems may be much smaller, since these systems are typically limited by chromatic dispersion rather than loss.

To measure optical margin, the essential apparatus is:

A complete and operational transmission system.
An instrument to measure transmission quality. For instance an instrument to measure Bit Error Rate or BER, or a signal / noise meter depending on the nature of the transmission.
Some fiber optic measuring instruments:
A Variable Optical Attenuator (VOA) to adjust the attenuation. This must have sufficient power handling capacity, it’s optical characteristics must not degrade the transmission, and it should be accurate at the operational wavlength(s).
An Optical Power Meter to measure the absolute light level, which must be accurate at expected power levels and wavelengths.

Thanks

[Rajguru M. Mohan]

Hi,
The margin, or the difference between the received signal-to-noise ratio (SNR) and the SNR required to maintain a given bit error
ratio (BER), is important to the design and operation of optical amplifier transmission systems.
The margin
in an optical amplifier system is the decibel difference between the received SNR and the SNR required to maintain the system error
rate specification. The received SNR, and therefore the margin, is
set by optical noise and waveform degradations accumulating over the entire length of the system.

Thanks,
Rajguru

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