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Fibre Optic communication P2P

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denujith

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Hi,

I have a requirement to send an analog signal (water level) to data processing center located ~1km away from the sensor. This area is prone to lightning and therefore I decided to use fibre optic cable to transmit the signal.

I need to know what components will be needed to transmit this analog signal to processing center.

Sensor Input -> [ADC] -> [Transmitter] -> [FO cable] -> [Receiver] -> Output (in digital form)

Is above the correct representation of achieving this?
If not, please advice me since I have never done a fibre optic communication project before.

Regards,
Lakmal
 

Hi,

You could use fiber cable...

But I think it is a lot of effort to bring it underground.

What about using RF?
Or internet, or mobile data transfer like GPRS?

Klaus
 

Have you researched the end preparation of your fibre cable, we paid £600 for the kit 30 years ago. This was for glass fibre. Perhaps you can get away with plastic?
Fibre optic comms is intrinsicaly digital, so we just bought RS232 fibre modems, in your case you will need to get from analogue to digital.
I suppose you could do a voltage to frequency conversion and build your own driver for the cable. Depends on your exact requirements.
Frank
 

I'd want to try a $5 laser pointer. Do you have line-of-sight several feet above ground? The laser can run on low power pulses.

Articles talk about beam divergence and aperture. With average values your spot of light could be a meter or two wide, at 1km distance. It pays to investigate cost versus performance.

To receive the beam, you may need more than a plain phototransistor or photodiode. Add a lens to gather more light. Perhaps a homemade dish reflector.

Someone will point out the danger to human eyes (and animal). That is why I said several feet above ground. It also depends on who or what has access to the path of the transmitting station.
 

KlausST said:
What about using RF?
Or internet, or mobile data transfer like GPRS?
Click to expand...

I'll describe my intended application in detail.

I need to know the water level at forebay tank and it is used to control the gate valve of the hydro turbine. We do not have internet, mobile data transfer or GPRS. There are no signals at the site. Site is vulnerable for lightning strikes. That is why I am looking for a fibre optic solution. I researched about ESP8266 and I didn't go forward with it since I have to protect it from lightning.

- - - Updated - - -

chuckey said:
we paid £600 for the kit 30 years ago.
Click to expand...

:O I never thought it would be so expensive. I was looking at this **broken link removed** and assumed I can use a LED/phototransistor as the transmitter/receiver.
 

30 years ago a mobile phone cost about $8.000, and now you can get for free as an offer from your carrier provider.

If you think that the cost of the fiber optic meet your budget, go for it. Is the best and safe option for these kind of applications.
 

The cost of fiber optic cable is far less than you will incur in laying the cable- labour and digging and getting permits and making the cable secure.

You may need a cable with power to put a repeater somewhere in between. If the cable is just 1 km in total length then it is perhaps not needed.
 

If the field is suitable, even a simple FM transmitter-receiver couple will work seamlessly.
No need to microwave Point to Point ,fiber-optic or any complex architectures.2.4GHz ISM band is pretty good for these kind of applications and there are tons of chip-set for this band.
 

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