Optical transceiver question

Jared Mauch jared at puck.nether.net
Wed Sep 7 21:26:41 UTC 2016

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 <frnkblk at 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

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