OTDR walks you to the cut.
Then you spool fiber over the ground between nearest splice points or nearest 
access to the damaged section.
Easy to get it restored.  Harder to fix it properly but at least the circuit is 
up while you work on the proper fix.  

I can blow fiber a half mile in a half hour if the conduit is good.  We 
frequently hit up to 300 feet per minute.  

From: Matt Hoppes 
Sent: Monday, February 25, 2019 9:47 AM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] Earthquake Fiber vs Microwave

Chuck,
Asking for my own edification here. Let’s assume an earthquake did sheer off 
fiber underground that you have buried. How do you time affectively determine 
where that fiber was cut, OTDR, and then manage to re-pull the new fiber 
perhaps a half mile or mile underground. 


Or are you coming up to the pedestals every thousand feet or so? Either way 
that’s still a significant amount of time to re-run that cable underground in a 
tube.
On Feb 25, 2019, at 11:43 AM, Bill Prince <[email protected]> wrote:



  Doesn't necessarily work after an earthquake. Roads, bridges, and so on are 
"unavailable" after an earthquake. You might not be able to get to a site, 
and/or the damage is so extensive, you need equipment that can't get to the 
site.  

  We've had earthquakes with significant horizontal displacement, and the 
microwave links have remained functional. Sometimes we've seen minor SNR 
dropoff, but not in most cases.

  I would make the argument that each can be a backup for the other. If a link 
is really important, having multiple paths (microwave AND fiber) is probably a 
better argument.

  --

  bp

  part15sbs{at}gmail{dot}com



  On Mon, Feb 25, 2019 at 8:31 AM <[email protected]> wrote:

    I know I can throw a temp chunk of fiber on the ground and have things up 
    and running in an hour or two.

    -----Original Message----- 
    From: Robert
    Sent: Monday, February 25, 2019 9:23 AM
    To: [email protected]
    Subject: Re: [AFMUG] Earthquake Fiber vs Microwave

    I would think that depends hugely upon the geography of the fiber run.
    Fault zones in california can shift 9-12 feet in very tight shear in a
    big one.   Look at some of the pictures from the last quake in AK and
    you can see 15-18 foot displacements in x y and z.  Would be tough to
    have confidence that your fiber would not get sheared in those
    conditions.   Might be tough to have a microwave link survive that as
    well but if the tower isn't 100 feet tall and is anchored in bedrock
    might not have as much trouble.  I don't know of any towers that went
    down in the Loma Prieta quake, the last large one I experienced.  But
    there might be some people on this list that have more data on that.

    On 2/25/19 8:10 AM, [email protected] wrote:
    > Trying to make the case that underground fiber will survive an earthquake 
    > better than mountain top microwave for public safety uses.
    >
    > -----Original Message----- From: Seth Mattinen
    > Sent: Monday, February 25, 2019 9:07 AM
    > To: [email protected]
    > Subject: Re: [AFMUG] Earthquake Fiber vs Microwave
    >
    > On 2/25/19 7:07 AM, [email protected] wrote:
    >> Anyone have some stories, perhaps from Alaska on earthquake 
survivability 
    >> of fiber and microwave?
    >> I have to go to a meeting with some lawmakers later in the week to make 
    >> the case that fiber has some slack, fiber can be fixed quickly.  Towers 
    >> can tilt or tumble.  Antennas can get misaligned.  And sometimes it is 
    >> impossible to get to a snowy peak for a weak during a storm.
    >> Fiber is scalable.  Microwave can be jammed and intercepted.  Etc etc. 
    >> Trying to be truthful and not gaslight anyone.
    >
    >
    > Just make sure your fiber doesn't run in conduit attached to any Cypress
    > Street Viaduct like structures.
    >

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