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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