Issue Description
Some times the engineers doesn't know how calculate the time that light wave needs to pass through the fiber and equipment, and this issue can help to the engineer for the OSN equipment trouble shooting.
Handling Process
The formula that calculate the time delay that light wave needs to pass through SDH system is the following:
T=(L*n1/c) + (0,1*M)
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T= Total Time Delay.
L= Is the distance (Km) between the source and sink of the service.
n1= Fiber refractive index. According to G.652 standard is 1,47.
c= Is the speed of light wave pass through vacuum （3×10^5 km/s）.
0,1= The time delay that one site transact VC3 is about 0.1 mS.
M= Site number for VC3 proceed between source node and sink node.
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Example:
Is necessary to calculate the time for one VC3 from node A to node E.
The topology is a chain A-B-C-D-E (five nodes) and the distances between them is the following:
A-B= 135,6 km
B-C= 109,6 km
C-D= 181,9 km
D-E= 175,2 km
TOTAL DISTANCE between A node and E node = 602,3 km
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n1/c = 4,9μs/km; so the time delay that light signal transmit in fiber is about 4.9μs/km, then we consider the system RS and MS generator will induct the little delay, so we could use 5μs/km to calculate the inducted time delay in the SDH system.
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T=(602,3km * 5μs/km ) + (0,1ms * 3)
T=(3,01ms) + (0,3ms)
T= 3,31ms; Total Time Delay that light wave needs to pass through SDH system from A node to E node.
Root Cause
Show the way to calculate the time that light wave needs to pass through the fiber and equipment.
