fiber optics

[cyb0rg777]

What is the cheapest wayt to set up a fiber optic link?
I need to transmit a signal up to 500 yards.
Also it should be very strong .And I need to tie it in a knot.
Basicaly ,I need to use in place of fishing line but still transmit data.
I have no experience with fiber optics so I need to know if this is possible and what I need to do it.

Thank you.

 

[dknguyen]

fiber optic cable can't be tied into a knot and isn't made for load bearing- it is just glass rod after all. its not rope.

 

[cyb0rg777]

I guess I was hoping maybe there was some kind of new fiber.

If I used regular optical fiber could I use regular ir diode and phototransistor
or do I need special made ones?

 

[Sceadwian]

You could use regular old fishing line for a fiber optic cable if you wanted to no idea what kind of performance you'd get at 1500ft.

 

[Marks256]

fiber optic cable can't be tied into a knot and isn't made for load bearing- it is just glass rod after all. its not rope.

No. Not true. At our school, our uplink is fiber optic. We have a ~3 foot fiber cable from the wall to the main switch tied into two knots for support.

I would not imagine that it would be very stable if the cable was any longer, but at about three feet it works.

 

[cyb0rg777]

I've been researching the subject.
This guy did some experiments with rishing line.

**broken link removed**

You can see he didn't get it to work.
The wikipedia page,

http://en.wikipedia.org/wiki/Fiber_optic

describes multimode fiber as a core fiber with a cladding that has a lower refractive index.
I think if the fishing line had a cladding on it it might work better.
I have some good ideas for a fiber like that.
Like building simple adapters to extend stuff like usb a long way.
But I don't know,I've never dealt with fiber optics.

 

[Sceadwian]

The type of fishing line is going to be very important, I can't find a reference to what kind was used for his testing. But according to further links on the Wikipedia reference to optical fiber mentions commercial plastic fiber's outer cladding is made of fluorinated polymers. This can be found in so called 'invisible' fishing line, as it's index of refraction is almost exactly the same as water. I think the key is to get two different layers to refract some of the light energy back down the cable. Probably only interesting to an experimenter.

 

[-=GST=- Nemisis (cs/cz)]

No. Not true. At our school, our uplink is fiber optic. We have a ~3 foot fiber cable from the wall to the main switch tied into two knots for support.

if you use plastic fibre you can tie it in knots very easily if you can find a datasheet or something i might even tell you how much it can be bent, glass i think is not as durable so i depends on what type of fibre.

 

[cyb0rg777]

This stuff looks like what I need.

**broken link removed**

If the small diameter stuff would work and they would sell it in the amount I needed.

**broken link removed**


I feel like Mcgyver with a roll of fishing line ,chewing gum,paperclip,tube socks,etc.

 

[CheapSlider]

The attenuation is given as 0.18db/m which means that over 500yds (=457.2m) you will have (0.18 x 457.2) = 82dB attenuation - thats a lot.

Even using 'professional' transmitters and receivers at each end I not sure if you could acheive that range. I would be extremely surprised if you could do it using ordinary leds and detectors.

 

[cyb0rg777]

Thanks for pointing that out.
I found this formula for attenuation.

[latex]P=PT*10^{-Al/10}[/latex]

P =output power
PT=transmitter power
A=attenuation in db/km
l=distance in kilometers

So the formula for a ten milliwatt diode with that length of that cable would be:

[latex]P=.01*10^{-(180*.5)/10}[/latex]

Which gives me 0 on my calculator.
I guess I need to get enough power out for a reciever.

 

[-=GST=- Nemisis (cs/cz)]

i get 1*10^-11

in that number the ^ symbol means to the power of. so this number is 0.00000000001, if you do the calculation as (0.01*10)^-(180*0.5)/10 then the answer is something like 10000000000. but dont trust my maths, its all razzamataz, i failed a-level math