The power change can be quantified as the ratio between the number of channels at the reference point after the channels are added or dropped and the number of channels at that reference point previously.We can consider composite power here and each channel at same optical power in dBm.
So when…
| Items | HD-FEC | SD-FEC |
|---|---|---|
| Definition | Decoding based on hard-bits(the output is quantized only to two levels) is called the “HD(hard-decision) decoding”, where each bit is considered definitely one or zero. | Decoding based on soft-bits(the output is quan… |
What is a OTDR ?
Optical Time Domain Reflectometer - also known as an OTDR, is a hardware device used for measurement of the elapsed time and intensity of light reflected on optical fiber.
How it works?
The reflectometer can compute the distance to problems on the fiber such as attenuation …
Non-linear interactions between the signal and the silica fibre transmission medium begin to appear as optical signal powers are increased to achieve longer span lengths at high bit rates. Consequently, non-linear fibre behaviour has emerged as an important consideration both in high capacity system…
**Multiplicative factor is just a simple math :eg. for ODU1/OPU1=3824/3808={(239*16)/(238*16)}
Here value of multiplication factor will give the number of times for rise in the frame size after adding header/overhead.
Example:let consider y=(x+delta[x])/x; In terms of OTN frame here delta[x] is i…
Optical power tolerance: It refers to the tolerable limit of input optical power, which is the range from sensitivity to overload point.
Optical power requirement: If refers to the requirement on input optical power, realized by adjusting the system (such as adjustable attenuator, fix attenua…
The main advantages and drawbacks of EDFAs are as follows.
Advantages
A Lower Order-ODU or LO-ODU is an ODUk, whose OPUk transports a inside mapped client.
An Higher Order-ODU or HO-ODU is an ODUk, whose OPUk transports an inside multiplexed ODUj.
LO-ODU and HO-ODU have the same structure but with different clients.
The LO-ODU is either mapped into the …
The ITU standards define a “suspect internal flag” which should indicate if the data contained within a register is ‘suspect’ (conditions defined in Q.822). This is more frequently referred to as the IDF (Invalid Data Flag).
PM is bounded by strict data collection rules as defined in stand…
Why does coherent detection introduce pre-FEC bit errors?
Why does FEC introduce latency?
The addition of FEC overhead at the transmit end and FEC decoding at the receive end cause latency in signal transmission.
Relationship between latency and FEC scheme types
Perform the following operations to measure OSNR using t…
In a non-coherent WDM system, each optical channel on the line side uses only one binary channel to carry service information. The service transmission rate on each optical channel is called bit rate while the binary channel rate is called baud rate. In this sense, the baud rate was equal to the bit…
What Is Coherent Communication?
Definition of coherent light
A coherent light consists of two light waves that:
1) Have the same oscillation direction.
2) Have the same oscillation frequency.
3) Have the same phase or maintain a constant phase relationship with each other. Two coheren…
As we know that either homodyne or heterodyne detection can be used to convert the received optical signal into an electrical form. In the case of homodyne detection, the optical signal is demodulated directly to the baseband. Although simple in concept, homodyne detection is difficult to implement …
Fiber splitters/couplers divide optical power from one common port to two or more split ports and combine all optical power from the split ports to one common port (1 × N coupler). They operate across the entire band or bands such as C, L, or O bands. The three port 1 × 2 tap is a splitter commonly…
Optical return loss (ORL) is the logarithmic ratio of the launch (incident) power divided by the total reflected power seen at the launch point. The total reflected power is the total accumulated reflected optical power measured at the launch caused by fiber Rayleigh scattering and Fresnel reflectio…
Bit error rate, BER is a key parameter that is used in assessing systems that transmit digital data from one location to another.
BER can be affected by a number of factors. By manipulating the variables that can be controlled it is possible to optimise a system to provide the performance levels th…
Q is the quality of a communication signal and is related to BER. A lower BER gives a higher Q and thus a higher Q gives better performance. Q is primarily used for translating relatively large BER differences into manageable values.
Pre-FEC signal fail and Pre-FEC signal degrade thresholds are pro…