I also use EXFOs and they will read to the meter, but if you have a fiber cut
out 25 miles, I will bet good money that when you dig up the spot where your
OTDR says the fault is, you will be off by 100 feet or more if you did not do a
test from the nearest splice point. In reality it will be off by thousands of
feet.
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: Ryan Ray
Sent: Tuesday, August 27, 2024 9:58 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] fiber patch cables
We use EXFO otdr's on some spans that are 160km and we can get it down to the
metre.
On Tue, Aug 27, 2024 at 7:07 PM Josh Luthman <j...@imaginenetworksllc.com>
wrote:
Don't you document where your splices are? If you see your splices every 33k
and see it's broken 1 mile from the last splice it should be pretty obvious, no?
On Tue, Aug 27, 2024 at 6:26 PM <ch...@go-mtc.com> wrote:
Magical device called a fusion splicer. Our reels were typically 33,000’
From: Josh Luthman
Sent: Tuesday, August 27, 2024 3:51 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] fiber patch cables
I don't see how you have a 50 mile span. Even if you get 80k reels that's
15 miles.
On Tue, Aug 27, 2024 at 5:19 PM <ch...@go-mtc.com> wrote:
When you have spans up to 50-75 miles at times, you have to use longer
high power pulses. There is a lot of variability in velocity of propagation,
earth temperature, splice slack loops, fiber twist. 1 mile error over 50 miles
is only 2%. You can easily be off by several thousand feet. You can’t just go
dig. You have to go to the closest splice point and test again, even then if
you it show the fault 2000 feet away and you dig at 2000 feet you may be off by
20 feet or more. I have been doing this for decades. Takes lots of digging to
actually find it.
From: Josh Luthman
Sent: Tuesday, August 27, 2024 3:01 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] fiber patch cables
A mile?! IDK how that's possible. Every time we turn a new splitter on
the sequentials and OTDR are within a few feet - we lose a couple of feet in
butt splices and our sequentials end up wrong. Every new reel gets tested on
delivery and it's right on.
When we had a broken fiber (ants) it was right on the case. When we had
a broken fiber (ribbon got knicked with installation) it was between two cases.
On Tue, Aug 27, 2024 at 3:48 PM <ch...@go-mtc.com> wrote:
Wow, sometimes looking for gopher damager over 20 miles I have been off
a mile.
From: Josh Luthman
Sent: Tuesday, August 27, 2024 1:30 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] fiber patch cables
So far every time we've used the OTDR it's been accurate within 1 foot.
On Tue, Aug 27, 2024 at 12:55 PM Trey Scarborough <t...@3dsc.co> wrote:
The only thing you have to worry about with shorter cables is the
reflection. In some instances with dirty connector at just the right connector
you can get reflection back in to the transmitter that can cause errors, the tx
to shut down or premature failure. This is very uncommon with LR 10G and less
optics and can be prevented from making sure you have clean connectors. Check
the RX and TX levels and make sure you don't have excessive loss. With 100G its
a little different story due to the combined power of multiple channels, but
still can be prevented by cleaning connectors, but in some instances Ive had to
use attenuation when mixing different vendor optics.
The using no launch on an OTDR most automatically calibrating OTDRs
will work without one. Your results can be off though. Most of the lower cost
ones are also lower powered and have less of an RX sensitivity so they don't
suffer as much from the reflections interfering when testing. I can test all
day long with my little otdrs without one, but my long range 200k+ units I have
to have a minimum of a 1k spool on it or you see ghosts. They will show up as
repeating events at even intervals. Not something you will see on shorter runs
either.
On 8/26/24 4:31 PM, Ken Hohhof wrote:
I should note that apparently I used to do this with direct attach
cables (DAC) but I think that was a pain, one more thing to stock and to bring
with for projects. Whereas I’d always have boxes full of SFPs and fiber patch
cords.
From: AF mailto:af-boun...@af.afmug.com On Behalf Of Josh Luthman
Sent: Monday, August 26, 2024 4:20 PM
To: AnimalFarm Microwave Users Group mailto:af@af.afmug.com
Subject: Re: [AFMUG] fiber patch cables
People say you need a launch cable but our cheap china OTDRs have
no issues seeing the connector at the end of the patch cable and stuff beyond.
I bought a big launch cable back in the day and never use it anymore.
Might be different with AE?
On Mon, Aug 26, 2024 at 5:16 PM <ch...@go-mtc.com> wrote:
Only minimum length I know of is the OTDR dead zone. If that is
a problem you purposely lengthen the cable with a launch cable.
From: Josh Luthman
Sent: Monday, August 26, 2024 1:59 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] fiber patch cables
Reddit is wrong. Gasp.
Connectors are loss, there is more loss in either one of the
connectors than there is the single mode glass.
Between a switch/router in a rack what I see all the time is long
(like 5/10/15 feet) cables and then put the slack in a loop along the posts.
On Mon, Aug 26, 2024 at 1:19 PM TJ Trout <t...@voltbb.com> wrote:
Patchbox makes some great products, their fiber system is
pretty slick but expensive.
Cable length is irrelevant it's optical budget / Rx signal
strength. Normally on 2-20k LR optics you are ok with any length cable, 40km+
needs a pad on short spans. (Attenuator)
On Mon, Aug 26, 2024, 8:29 AM Ken Hohhof <khoh...@kwom.com>
wrote:
Is there a minimum length for a single mode fiber patch cable?
I have been using 1 meter cables and they are almost always
too long, I’m talking about going between routers and switches in a rack, stuff
like that. I see that FS sells 0.5 meter cables, but I saw somewhere like
maybe on Reddit someone claiming there was a minimum length. Given SM fiber
and LR optics, I don’t see how 0.5 or 1.0 meter would be different they are
both essentially zero length.
Probably there’s some kind of cable tray or cable management
solution I could be using but I’ve never liked such things.
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