As I recall, it passes 1650 so you can put it on the end of a PON and shoot
through splitters.
It does not allow any other wavelenth out that could jam the OLT and cause the
PON to go down.
Some OTDRs have these filters built in when you are testing on 1650.
Also, the filter keeps the pon outbound transmit light from messing with the
OTDR receiver.
I think OTDR inputs are wide band so they will see the OLT signal along with
the reflected test signal without the filter.
From: Josh Luthman
Sent: Wednesday, April 19, 2023 2:03 PM
To: ch...@go-mtc.com
Cc: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] OTDR transmit power
Does it just need to filter 1310/1490 so the OTDR doesn't see it and then you
can shoot 1550?
On Wed, Apr 19, 2023 at 3:58 PM <ch...@go-mtc.com> wrote:
Just a lump in a fiber jumper with connectors on each end. Would take some
digging to find it.
From: Josh Luthman
Sent: Wednesday, April 19, 2023 1:40 PM
To: ch...@go-mtc.com
Cc: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] OTDR transmit power
Got a picture at least?
On Wed, Apr 19, 2023 at 3:35 PM <ch...@go-mtc.com> wrote:
I tried to find a link, we have one, but I don’t know where I got it.
Perhaps a custom fiber filter from fs.com
From: Josh Luthman
Sent: Wednesday, April 19, 2023 1:23 PM
To: AnimalFarm Microwave Users Group
Cc: ch...@go-mtc.com
Subject: Re: [AFMUG] OTDR transmit power
That's clever! Nice tip, thanks.
On Wed, Apr 19, 2023 at 3:15 PM Chuck McCown via AF <af@af.afmug.com> wrote:
There is a band pass filter you can add for shooting over live fiber.
From: Josh Luthman
Sent: Wednesday, April 19, 2023 11:27 AM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] OTDR transmit power
On Calix optics they say it's OK if the OTDR hits it with 1650. I don't
think an OTDR will shoot if it sees 1310/1490.
On Wed, Apr 19, 2023 at 1:03 PM <dmmoff...@gmail.com> wrote:
Oh I 100% believe they could do it. If I knew tx power of the OTDR it
would be easy to estimate how close they’d have to be to exceed the overload
threshold of the transceiver.
“Dynamic Range” has to be a diff between Tx and sensitivity …..or so I
would assume. If it is then I could guess that maybe half the range is from Tx
and half from Rx? So a 50dB range might mean +25Tx? I mean that all seems
plausible to me, but it’s a lot of assuming. I just wish this number was on
the spec sheet.
The alleged location of the case they were in was over 200,000 ft away.
A ZR is a bit sensitive, but that OTDR would have to be pretty damn strong to
nuke it from that distance. Maybe it is that strong, or maybe they’re lying to
me. So a second part of the equation is whether I trust what this crew tells
me in the future. With same guys we had a link we were troubleshooting
suddenly come up 20 minutes after they were “hands off”. So I already think
they might be compulsive bullshitters.
From: AF <af-boun...@af.afmug.com> On Behalf Of Chuck McCown via AF
Sent: Wednesday, April 19, 2023 11:57 AM
To: AnimalFarm Microwave Users Group <af@af.afmug.com>
Cc: ch...@go-mtc.com
Subject: Re: [AFMUG] OTDR transmit power
These guys think so:
https://content.jwplatform.com/previews/IQitGvAV
Best Regards,
Chuck McCown
McCown Technology Corporation
8401 N Commerce Dr
Lake Point, Utah 84074
801-250-9503 Office
435-830-4306 Cell
www.mccowntech.com
www.microtrench.pro
www.terabitnetworks.com
From: dmmoff...@gmail.com
Sent: Wednesday, April 19, 2023 9:23 AM
To: 'AnimalFarm Microwave Users Group'
Subject: [AFMUG] OTDR transmit power
Does anyone know how strong the pulses from an OTDR might be? Is there
a rule of thumb to guess that based on the dynamic range?
I’m trying to determine if a dark fiber provider might have blasted a
ZR optic with an OTDR at close range. We know they were out testing recently,
and the manufacturer is saying receiver may have been overloaded and the link
is way too long for the far end transceiver to have done it.
I’m not out to blame anybody, this is just an educational exercise.
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