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Running fiber optic to observatory

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#1 cmaier

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Posted 17 August 2019 - 10:11 AM

I'd like to run fiber cable from the house to the Observatory computer. It's only about a 90' run. It's to put the internet in the dome and team viewer into the computer to run the Telescope etc. My questions are:

1. Single mode or multi mode cable?

2.Simplex or duplex converters

3. LS or SC connectors

 

I understand the cable connectors have to be compatible with the converters, but seems I have a choice. 

 

I wanted to reach out to people that have experience with fiber.  Thanks in advance!



#2 D_talley

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Posted 17 August 2019 - 10:57 AM

I ran multimode fiber to my observatory using duplex converters and SC connectors that matched the connectors on the converters. Very simple job and worked like a champ. 



#3 Migwan

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Posted 17 August 2019 - 11:02 AM

With data up to over 1Gb/s on coax now, especially at short distances, fiber may not be necessary, even if you are lucky enough to already have fiber to the house.   Do you have fiber to house and what speed either way?  

 

Single mode is faster less error, but again, what speed desired?

 

jd


Edited by Migwan, 17 August 2019 - 11:03 AM.


#4 TMO

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Posted 17 August 2019 - 11:09 AM

Another option is line-of-sight radio transmission with a Ubiquiti Nanostation: 

https://www.amazon.c...sl_5i9cfjbynm_e



#5 MCinAZ

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Posted 17 August 2019 - 11:40 AM

I'd like to run fiber cable from the house to the Observatory computer.

...

I wanted to reach out to people that have experience with fiber.

There's a long-running (and highly amusing, at times) thread at Stargazers Lounge where this topic is discussed. If you want to cut to the chase, scroll down to the advice provided by discardedastro here: https://stargazerslo...-build/page/39/

 

You make the comment that it's "only about 90'", however that's more than enough distance to experience an induced transient from nearby lightning strikes sufficient to do serious damage to your equipment. I wouldn't want a copper run that long if I was in an area with any possibility of thunderstorms. An RF link may be a suitable alternative, but can be a lot harder to troubleshoot without specialized equipment if interference or signal quality issues intrude. Where I work, we have many high speed data links between buildings, some on mountain tops where lightning activity is common, and essentially everything is linked using fiber. One of the last links which wasn't was a serial line running through a buried conduit from a dome to its control room located less than 20 meters away. A nearby strike resulted in a peripheral card with a literal smoking hole in it the year before last.



#6 brave_ulysses

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Posted 17 August 2019 - 12:34 PM

10g + multimode + lc connectors = no waiting

 

https://www.cloudyni...38-10g-network/

 

https://www.cloudyni...5/#entry8427521

 

good luck!



#7 discardedastro

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Posted 17 August 2019 - 02:13 PM

There's a long-running (and highly amusing, at times) thread at Stargazers Lounge where this topic is discussed. If you want to cut to the chase, scroll down to the advice provided by discardedastro here: https://stargazerslo...-build/page/39/

 

You make the comment that it's "only about 90'", however that's more than enough distance to experience an induced transient from nearby lightning strikes sufficient to do serious damage to your equipment. I wouldn't want a copper run that long if I was in an area with any possibility of thunderstorms. An RF link may be a suitable alternative, but can be a lot harder to troubleshoot without specialized equipment if interference or signal quality issues intrude. Where I work, we have many high speed data links between buildings, some on mountain tops where lightning activity is common, and essentially everything is linked using fiber. One of the last links which wasn't was a serial line running through a buried conduit from a dome to its control room located less than 20 meters away. A nearby strike resulted in a peripheral card with a literal smoking hole in it the year before last.

Hah - I get around and don't even notice. Just figured I'd browse around over here, thought "hey, I know something about that.." and it turns out I've pre-empted myself...

 

I'd definitely do fiber for 90', for all the reasons you've listed. Media converters are cheap and pre-made cable to length is also cheap. I'd absolutely stick to singlemode though. It's much more forgiving of distance, is where all the cable innovation is happening (G.657.A2 can tolerate crazy bends, if you have a tricky install), and is just as cheap. Used to be, 10 or so years back, multimode was half the cost - these days the only time multimode is used is between adjacent racks in a datacentre or within a rack. Use duplex - again, simpler, easier. BiDi optics (which only use a single fiber) exist and work fine but are less standard so you'll pay more. LC vs SC is entirely up to you, but SFP/SFP+ modules are all LC so if that's what you're plugging into, sticking to LC is probably as good a plan as any.


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#8 t-ara-fan

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Posted 17 August 2019 - 02:29 PM

https://www.amazon.c...r/dp/B002FWDE36

How about optically isolated 100Mbps Ethernet.

#9 discardedastro

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Posted 17 August 2019 - 02:48 PM

https://www.amazon.c...r/dp/B002FWDE36

How about optically isolated 100Mbps Ethernet.

There's a lot of "gotchas" with this sort of thing - at 100Mbps it can work as optoisolators are fast enough but gigabit is well beyond what most optos can deal with.

 

You can get passive lightning suppressors for gigabit which work, but to be honest, the cost of fibre is now so low that it's often more expensive. Even that 100Mbps box is ~$100 - I can get two SFPs and a fair bit of fibre for that from fs.com and similar vendors, and it'll work fine at 1G and 10G in future.

 

Anything leaving a building for permanent install, unless you're going ~10-20ft or so, fibre is the way to go.



#10 Migwan

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Posted 17 August 2019 - 09:18 PM

Wow, can't believe prices have come down that much.  Been just a few years removed but really not much reason to go coax now. 

 

As far as lightning vs copper clad steel, that is a matter of proper grounding. 

 

jd




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