Yes, if it is a strike you don’t even need the OTDR. Just drive the route and
stop where they are digging.
Sometimes splices go bad and normally the OTDR indicates a distance very close
to a splice point so that is easy too.
Gophers, never easy.
From: Ken Hohhof
Sent: Thursday, August 29, 2024 11:06 AM
To: 'AnimalFarm Microwave Users Group'
Subject: Re: [AFMUG] fiber patch cables
Sounds like gophers are a lot worse than somebody digging in the wrong spot,
because once you are close you can just look for the above ground evidence like
a hole or an excavator with yellow vest people standing around.
What were the critters than Bill Murray was at war with in Caddyshack, were
those gophers? Dumb movie, but iconic I guess.
From: AF <af-boun...@af.afmug.com> On Behalf Of ch...@go-mtc.com
Sent: Thursday, August 29, 2024 11:43 AM
To: AnimalFarm Microwave Users Group <af@af.afmug.com>
Subject: Re: [AFMUG] fiber patch cables
Index of refraction (IOR) differs from reel to reel. If you need accurate
distance measurements you have to enter a precise index of refraction, and the
IOR can vary with distance as well.
The internal timebase drifts. Clock errors and stability cause accuracy
issues.
Pulse width and sample interval adds precision errors. Longer distances need
wider pulses so you lose precision.
So with a loss of both precision and accuracy that is proportional to distances
being shot, you are never going to walk right up and dig up the correct spot.
Bottom line, long cables, gopher faults, you will spend lots of time digging
along the line to find it.
From: Josh Luthman
Sent: Thursday, August 29, 2024 10:22 AM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] fiber patch cables
1.01x
20,300 foot cable reel is 20,500 of glass
On Thu, Aug 29, 2024 at 9:01 AM <dmmoff...@gmail.com> wrote:
That and fiber distance is not equal to cable distance because of the twist
built into the buffer tubes.
From: AF <af-boun...@af.afmug.com> On Behalf Of ch...@go-mtc.com
Sent: Wednesday, August 28, 2024 5:05 PM
To: AnimalFarm Microwave Users Group <af@af.afmug.com>
Subject: Re: [AFMUG] fiber patch cables
Good point, with direct bury the sequentials are frequently rubbed off.
From: castarritt
Sent: Wednesday, August 28, 2024 2:42 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] fiber patch cables
Yeah, with direct bury and no handhole for miles, you are in a tough spot.
If the footage marker on the cable you dig up is still there, you could go off
that instead of guessing or cutting.
On Wed, Aug 28, 2024 at 2:58 PM <ch...@go-mtc.com> wrote:
When you are out in the desert tracking direct bury fiber, only handholes
are splice points.... good luck.
If the closest hand hole is 2 miles away from the area of the fault, good
luck. You will wheel it off, read the sequential, then wheel it off again, dig
again. Not find the damage. Then you have the choice to cut and shoot it
again or just start exposing cable. Flip a coin to choose which way to start
digging and start digging. Have dug for hundreds of feed looking for damage
and sometimes it is very hard to see. Sometimes a gopher will just eat into
the side of a cable a little bit.
You can strip it and have someone put a visible light on it if you are not
too far away for that to work. That can tell you if you are on the CO side of
the fault. There are also those bendy fiber detectors that can help with that
too. Hopefully you find it close enough that you can put a handhole near where
you stripped it. Always takes two handholes or peds to fix. And LOTS of
digging.
From: castarritt
Sent: Wednesday, August 28, 2024 1:49 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] fiber patch cables
Shouldn't you be able to look at the distance to fault from the last
splice, look up the cable footage marker going into that splice closure (go
check it if you didn't document that when it was built), check footage marker
at closest handhole, and then wheel it off from there?
On Wed, Aug 28, 2024 at 2:42 PM <ch...@go-mtc.com> wrote:
So on a 15 mile shot with a problem somewhere in the middle, you think
you can wheel it off and dig it up and find it?
One shot, from the end. Walk right to the problem?
From: Josh Luthman
Sent: Wednesday, August 28, 2024 1:07 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] fiber patch cables
That hasn't been my experience, but at the same time we're not 25 mile
shots - it's maybe 15 max.
On Wed, Aug 28, 2024 at 11:43 AM <ch...@go-mtc.com> wrote:
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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