Wired Telephone Extension for 1.7 km

I don't know what your country's laws are, but I would say have a look at long wave radio transmission, ferrite rod, 100 kHz type of frequency, nice, easy and cheap to make, it may need a big aerial but the signal does tend to 'go round corners' so to speak...

Its worth a try, better than laying 1 mile of twin core down and then finding its not good enough!!

John.

Dear All,

Thanks for your valuable thoughts to solve my matter.

I'm writing this from Sri Lanka, where there are lot of restrictions for private wireless communication.

We do have 230 V supply at both end, but from different transformers.

I'm just guessing, but the current requirements are extremely small, and I would think standard 18 gauge bell wire would be sufficient, and cheap enough to experiment with. Additionally you can always amplify a weak signal, on the receiving end.

There may be an additional possibility. Is there a point between the two locations that share a common line of sight. If there is it would be very simple, and very economical to set up a low-power repeater.

PS. I agree with John. It's just plain too much work nowadays to lay down a mile of wire. With copper prices being what they are, the electronics would probably be cheaper.

A Repeater would work nicely and on Battery power/ solar charger.

Why not try a fiber optic lines and connected to the N-Tron ethernet modules. Check with your equipment if it can be connected on the above modules, you may inquire also from Ntron technical support group with your problem

1.7km is about 5500ft, so if you are powering it with 48Vdc, a 26 AWG pair should be fine. All you need to do is provide 23ma to power the touch tone pad. I don't know what type of amp you will be using, but if it is putting out at least 1mw of power then you should be getting about -3dBm at the far end.

Hi Asitha,

I used a system like the one Guest just mentioned in the 1980's.

It's called "Line Carrier Communication". 140 Khz (10 khz bandwidth pretty narrow)

on a 60Hz power line.

Both sites were powered from the same power source.

I communicated over a mile with about 100 mw.

It was voice, but can be used for data as well.

However data xmission on such a narrow bandwith is quite slow.

You'll have to use FM modulation or one of the modes of FSK for tx and rx data.

There is a lot of AM noise on a power line.

all the best

Jens

2 dsl modems back to back work you need to set up the modems right

Over 1.7 Km 24 AWG will give you about 26 dB loss and should cost you less than $250 (for 2 pair wire).

You'd need to go up to about 16 AWG to get the loss down to about 12 dB (which would be OK without boosting the signal at either end).

Randall, don't forget the cost of an outer protective jacket and the cost of digging a one mile trench to try to protect the cable...

Its going to be expensive if its going to have to last...

John.

Good point!

I guess your signature line says it all--

Don't worry Randall, we all make arses of ourselves at some time or other LOL

We wouldn't be human if we were always correct.

John

24 AWG has .7dB of loss per 1000 ft at 1000Hz.