Advertisement
Typically, most problems encountered with the TC3026 are related to optic receiver overdrive. The maximum
optic power that can be received without distortion is referred to as the optic receiver's "saturation level."
When the incoming optic power is greater than the saturation level of the receiver, optic "overdrive" can
occur.
The TC3026's optic receivers have a typical saturation level of -5 dBm. Reference optical saturation levels
on the Optical Specifications Section on page 3. E.g., if the user's equipment's launch power is higher than
-5 dBm (i.e. -4 dBm or greater) and the fiber run is very short and has low signal loss, it is likely to overdrive
the TC3026's Multimode receiver. The consequences of overdrive can be high error rates or the device's
failure to recognize the incoming optic signal at all.
The TC3026 has been adjusted at the factory so that the Single Mode transmitter will not overdrive the Single
Mode receiver even when short cables are used to connect them; hence, the overdrive condition happens
most frequently at the Multimode receiver optic.
If you suspect the Multimode receiver has an optic overdrive condition, a simple test will help verify it. At
the receiving optic in question, simply disconnect the optic connector and back it out of the receptacle (about
1/8 of an inch), creating a gap between the fiber connector and the receiver. Verify that the equipment is
still in "sync" with the optic signal and that the overdrive condition has been corrected. To resolve the
overdrive condition permanently, insert a 5dB or 10dB in-line attenuator into the problem link. In-line
attenuators can be purchased from Metrotek* at (727) 547-8307. The part numbers are:
In-line attenuators are used to correct optic overdrive conditions that may exist on either side of the TC3026s.
The following is a typical diagram illustrating a TC3026 Mode Converter used to convert a 1310nm Single
Mode optical signal from a Single Mode Device into a 850nm Multimode optic signal to be received by a
Multimode Device.
MNL-30260-01-00
Advertisement
