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Chromatic dispersion causes the pulse broadening effect along the transmission distance, as the group velocity of frequencies of the laser pulse is a function of the frequency. That is each frequency in laser pulse travels with different velocity leading to pulse broadening at the receiver end. This broadening causes the overlapping of adjacent bits at the receiver causing transmission errors. Chromatic dispersion is measured in ps/ (nm*km). Typical value for a G.652 single mode fiber is 18 ps/ (nm *km). That means a laser pulse of width 1nm broadens in time by 18 ps when it travels 1 Km distance.
Two types of dispersion compensations are supported. Fiber-Bragg Grating (FBG) based dispersion compensation and fiber based dispersion compensation to support multichannel DWDM transmission.
As these are purely passive units, they are housed in external 19” sub racks.
Two DCM cards plugged into 1 RU 19” sub rack.
It is purely a passive card or unit.
There is no LED visual indication for this card or unit.
Following types of DCM are available which can be used for various amount of dispersion compensation.
Types of DCM
Description |
Model number |
|---|---|
Fiber based Dispersion Compensation Unit-10km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-10-CB |
Fiber based Dispersion Compensation Unit-20km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-20-CB |
Fiber based Dispersion Compensation Unit-30km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-30-CB |
Fiber based Dispersion Compensation Unit-40km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-40-CB |
Fiber based Dispersion Compensation Unit-50km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-50-CB |
Fiber based Dispersion Compensation Unit-60km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-60-CB |
Fiber based Dispersion Compensation Unit-70km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-70-CB |
Fiber based Dispersion Compensation Unit-80km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-80-CB |
Fiber based Dispersion Compensation Unit-90km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-90-CB |
Fiber based Dispersion Compensation Unit-100km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-100-CB |
Fiber based Dispersion Compensation Unit-110km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-110-CB |
Fiber based Dispersion Compensation Unit-120km for G.652 fiber, C Band, LC/PC. |
DCU-652-C-120-CB |
1RU Sub Rack for dual DCU. |
DCUH01 |
Fiber Bragg Grating based Dispersion Compensation Module-10km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-10-CB |
Fiber Bragg Grating based Dispersion Compensation Module-20km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-20-CB |
Fiber Bragg Grating based Dispersion Compensation Module-30km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-30-CB |
Fiber Bragg Grating based Dispersion Compensation Module-40km for G.652 fiber, C Band, LC/PC |
DCM-652-C-40-CB |
Fiber Bragg Grating based Dispersion Compensation Module-50km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-50-CB |
Fiber Bragg Grating based Dispersion Compensation Module-60km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-60-CB |
Fiber Bragg Grating based Dispersion Compensation Module-70km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-70-CB |
Fiber Bragg Grating based Dispersion Compensation Module-80km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-80-CB |
Fiber Bragg Grating based Dispersion Compensation Module-90km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-90-CB |
Fiber Bragg Grating based Dispersion Compensation Module-100km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-100-CB |
Fiber Bragg Grating based Dispersion Compensation Module-110km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-110-CB |
Fiber Bragg Grating based Dispersion Compensation Module-120km for G.652 fiber, C Band, LC/PC. |
DCM-652-C-120-CB |
1RU 19'' Sub Rack for dual DCM. |
DCMH01 |
Typical specification and functionalities of the DCM modules are as follows:
Typical Specifications of DCMs
Model number |
Nominal Dispersion at 1550nm ps/nm |
Max Insertion Loss(dB) |
Ripple-dB |
Maximum PMD (ps) |
Latency(ns) |
|---|---|---|---|---|---|
DCU-652-C-10-CB |
170 |
1.9 |
0.4 |
0.25 |
6100 |
DCU-652-C-20-CB |
340 |
2.6 |
0.4 |
0.3 |
12300 |
DCU-652-C-30-CB |
510 |
3.4 |
0.45 |
0.4 |
18400 |
DCU-652-C-40-CB |
680 |
4.1 |
0.5 |
0.45 |
24600 |
DCU-652-C-50-CB |
850 |
4.8 |
0.55 |
0.5 |
30700 |
DCU-652-C-60-CB |
1020 |
5.6 |
0.65 |
0.55 |
36900 |
DCU-652-C-70-CB |
1190 |
6.3 |
0.65 |
0.6 |
43000 |
DCU-652-C-80-CB |
1360 |
7 |
0.8 |
0.6 |
49200 |
DCU-652-C-90-CB |
1530 |
7.8 |
0.85 |
0.65 |
55300 |
DCU-652-C-100-CB |
1700 |
8.5 |
0.9 |
0.7 |
61500 |
DCU-652-C-110-CB |
1870 |
9.2 |
1 |
0.7 |
67600 |
DCU-652-C-120-CB |
2040 |
10 |
1.1 |
0.75 |
73700 |
DCM-652-C-10-CB |
170 |
3.8 |
0.8 |
1.4 |
90 |
DCM-652-C-20-CB |
340 |
3.8 |
0.8 |
1.4 |
100 |
DCM-652-C-30-CB |
510 |
3.8 |
0.8 |
1.4 |
110 |
DCM-652-C-40-CB |
680 |
3.8 |
0.8 |
1.4 |
120 |
DCM-652-C-50-CB |
850 |
3.8 |
0.8 |
1.4 |
130 |
DCM-652-C-60-CB |
1020 |
3.8 |
0.8 |
1.4 |
140 |
DCM-652-C-70-CB |
1190 |
3.8 |
0.8 |
1.4 |
150 |
DCM-652-C-80-CB |
1360 |
3.8 |
0.8 |
1.4 |
155 |
DCM-652-C-90-CB |
1530 |
3.8 |
0.8 |
1.4 |
165 |
DCM-652-C-100-CB |
1700 |
3.8 |
0.8 |
1.4 |
170 |
DCM-652-C-110-CB |
1870 |
3.8 |
0.8 |
1.4 |
170 |
DCM-652-C-120-CB |
2040 |
3.8 |
0.8 |
1.4 |
170 |