BER in one direction only

I lease some SMF strands about 15km long, over which I'm using CWDM (1490-1610nm GBICs). I am shooting different colors in different directions over a single strand, so electronics at each end of the strand are transmitting at some wavelengths, and receiving at others.

On one strand, all GBICs at one end of the fiber show CRC errors on the data being received; the GBICs at the other end of this strand show no CRC errors. I tried testing using a second strand, with ZX GBICs (1550nm, 2 strands, no CWDM mux), and I find that the same end consistently receives CRC errors over the suspect fiber strand. But if that end transmits over the suspect strand, the other end has no CRC errors. It seems as though the suspect strand only causes trouble for light transmitted in one direction.

Unfortunately, I don't have any real FO test equipment beyond a power meter. My fiber provider shot both ends with an OTDR and said "looks good to us"; any hints on what I should ask for to get them to see what I'm seeing?

Thanks, Phil

Reply to
Phil Begriffenfeldt
Loading thread data ...

Phil, 'hate to say this... Optically all I can think of is dirty connectors, noting the duplex fiber links are 2 separate fibers, so one is ok and other isn't(?) Heck of a coincidence (all the same direction), but I know some folks just don't get how to clean. I don't understand the OTDR ok unless somebody not telling the truth or testing right. The end nearest the problem Rx is slightly more suspect. Inspect fiber connecor ends with a microscope (WITH LIGHT OFF!) There are no known directional phenominon that you haven't already elimnated with your Passives removal test. I would keep the pressure on the leaser to do this for you while checking electronic issues at the problem end.

Reply to
Bruce

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.