@mohamed A.A.Abouseif
Dear Mohamed,
Thanks alot for your reply , in the file i pasted only downstream is working with satisfactory BER but when it comes to upstream i am not using any optical fiber and still im not able to get any ber ,and i want to use hear bidirectional fiber , but i am unable to use it here. one more file i created in past ,i am attaching my new file here also i am unable to get upstream ber .
Dinesh pratap