Re: Optical transceiver question

[Jared Mauch <jared () puck nether net>]

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 () 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