Anamika i found a way to calculate dispersion.You can place OTDV on the starting and ending point of your optical fiber.Deselect the automatic range and do this operation
1)Select BIT
2)Start =0
3)End value=10,20 (how many bits you want to see
4) Right click,select marker
5)place on leading edge and trailing edge of pulse,you will get the time of one pulse
6)same you do after SMF and you will get value of dispersed pulse
Please correct me if i am wrong anywhere.