The use of laser in open sight networking

Abbabbj

actually the use of laser in wireless networking is very old i know that it was used inn the 80's but nowdays laser are more cheaper more powerfull (longer range and light intensity and with a verry little pulse time (i have heared that the accuarcy of pulse in some lasers could reach a micro second) and the light recptors are also verry accurate and with very sensitive (milli sec sensetivity)
I am SURE that theuse of laser in networking right now is IMPOSSIBLE but in the near future in advanced countries they will settel a new kind of directed (linear) tranasmitters to aviod network counterfiering and sniffing (hacking)
I am not a network expert but is there any kind of completly linear transmiter?
(transmit like a laser beam)

J4D

it is actually done , in Lebanon as well , fransabank 'i guess' utilized this type of network to link one of their branches in ashrafiyye with the central office :) with speeds up to 1GB/s !
if you want more info about how it works dont hesitate to ask .

with a small transformer a laser and a photo resistor you can make a small receiver and transmitter to transmit your own voice over laser ! :)

check this http://www.geodesy.hu/en/geodesy_fso/main_menu/home.html#

Abbabbj

Thanx jad for info
i know how it works it is very old idea but it is more compatible with modern technology and i think i need more time to be available to all people

Technical data
Electrical characteristics
Light source: laser diode
Laser diode power: 4 × 10 mW
Detector: APD
Dynamic range: >25 dB
Bandwidth: 1 Gbps
BER: 10-9
System latency: <50 ns
Power required: +12 V, -12 V
Data in/out:
Fast ethernet: 1.25 Gbps
Optical characteristics
Wavelength: 785 nm
Beam divergence: 2–5 mrad
Receiver acceptance angle: 8.5 mrad
Laser class: Class 1M
Environment
Operating temperature: -20°C – +60°C
Storage temperature: -40°C – +80°C
Centigrade humidity: 95% non condensed
Protection rating: IP65
Operational distnace: 650–1,500 m

arithma

Can this possibly be used to connect Saida to Beirut?
Isn't microwave much less susceptible to the elements? My microwave connection didn't use to glitch even in the worst storms.

J4D

get a powerful laser , calculate the curvature of earth and you can make it , but its impractical . the only advantage of laser over microwave is more security and less interference .

nuclearcat

Laser is max 3-4 km.
In major part of Lebanon it wont work well because of "smog". Additionally you will need to clean lenses very carefully each month.
Add that many small buildings here dont have proper construction and shaking even when truck pass nearby, this means laser will loose a lock.

J4D

nuclearcat wroteLaser is max 3-4 km

that's with the regular devices that exist today , but rationally and logically it can be farther(a lot) .

nuclearcat

jadberro - refraction and attenuation will make longer link extremely unreliable.
Current level of technology limited i think max 5-10 km, for next 1-2 years, if there is no serious new inventions will be made.

J4D

absolutely not , they are measuring distance between the earth and other planets using lasers ! , with a laser powerful enough , you can achieve what you can do with microwave.
from where will refraction come from ?! its traveling throe thin air , attenuation ?! add more power and you solve that !

I'm not trying to prove you wrong .

arithma

Air temperature difference refracts light.
Attenuation comes from the opaque particles with respect to laser (dust particles block lasers, not microwave, I guess)
The attenuation in data you're talking about I believe is different.
Some physical systems require exponentially more resources to increase a value (reach in this case) linearly; I am just trying to understand and speculating. Perhaps if we need to connect over 45KM, we'll need to make a laser so powerful it will cut through anything in it's direction and heat up the thin air.
Green lasers that are draw lines in thin air don't work in pure vacuum. That should give a hint about the type of attenuation.

J4D

heheh a dust particle over 45 km ! or is that a dust bunny ! :P and the temperature ?! we are talking about massive differences which generally do not exist on a span of 45 KM unless you are sending data to arez :P! or Everest . your idea is fully feasible .

eurybaric

and the temperature ?! we are talking about massive differences which generally do not exist on a span of 45 KM unless you are sending data to arez

i guess the slightest change would make a BIG difference over 45 km

The idea is very interesting though!