We have seen cases where the patches introduce enough loss to cause a lot of loss. Have you done an OTDR on each link?
Jared Mauch > On Sep 7, 2016, at 4:23 PM, Frank Bulk <frnk...@iname.com> wrote: > > We recently purchased some generic optics from a reputable reseller that > were marketed to reach 60 km. > > But what we found, based on the spec sheets, is that it could only reach > that distance if the optics were transmitting on the high side of the > transmit power range. > > For example, if the TX range was 0 to +5 dBm and minimum RX power was -20 > dB, the designed optical budget should be no more than 20 dB (0 - -20). > Based on the wavelength the appropriate loss would be 0.4 dB/km and results > in only 50 km, not 60 km. To get 60 km it would need 24 dB of link margin, > and that would only be attainable if it was transmitting on the high side, > at +4 dBm. > > Is it an industry practice to market distance based on the hot optics, not > on the worst case, which is minimum TX power? > > Frank