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Commentator

Join Date: Dec 2006
Posts: 76

Wired Telephone Extension for 1.7 km

04/04/2008 12:31 AM

Dear Sir,

We need to connect two remote sites through a wired link to communicate (voice only) between two locations which were apart from 1.7 km. Since this is a hilly area & other restrictions it is not possible to have a wireless system.

Can we have a larger gauge wire connection to communicate between those two locations?

IF that is so what is the criteria of selecting the required gauge of the wire? like maximum allowable resistance of the wire..etc

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Guru
United Kingdom - Member - New Member Engineering Fields - Instrumentation Engineering - New Member Fans of Old Computers - Vector 1 - New Member

Join Date: Jul 2006
Location: Dunstable, England
Posts: 2480
Good Answers: 33
#1

Re: Wired Telephone Extension for 1.7 km

04/04/2008 10:44 AM

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.

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Commentator

Join Date: Dec 2006
Posts: 76
#14
In reply to #1

Re: Wired Telephone Extension for 1.7 km

04/09/2008 10:42 PM

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.

Power-User

Join Date: Dec 2007
Posts: 231
Good Answers: 3
#2

Re: Wired Telephone Extension for 1.7 km

04/05/2008 12:36 AM

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.

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Power-User

Join Date: Jan 2007
Location: Walkersville, Md, USA
Posts: 138
#5
In reply to #2

Re: Wired Telephone Extension for 1.7 km

04/05/2008 9:16 AM

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

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#3

Re: Wired Telephone Extension for 1.7 km

04/05/2008 1:00 AM

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

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#4
In reply to #3

Re: Wired Telephone Extension for 1.7 km

04/05/2008 6:13 AM

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.

2
Guest
#6

Re: Wired Telephone Extension for 1.7 km

04/05/2008 4:05 PM

Dear Sir, Do you have at least 115vac/230vac to both these locations, both from same supply? If so, the Voice Intercom System you can use is working mounted on the wall in my home, and down at my shop for the other send/receiver. The distance it will work is only limited to the fact that it must be plugged into the same power source, as the Voice Circuit uses the Ground & one of the Line leads as the Carrier Circuit. These Units have been on the market in Canada as a Hobby Kit, Purchased from Radio Shack, originally a section of the Tandy Leather Co. (Radio Shack has gone out of Business here, but same locations are still operating under a New Co. Name.) I hope this fits your reqirement. If the Power supplies are the same, your question about wire gauge, is already solved by your Electric server. Also the cost of the two Send/Receiver Units Assembled Kits is about Thirty Dollars Canadian. Carl

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Commentator

Join Date: Jan 2006
Location: Worthington Northern Ontario Canada.
Posts: 64
#7

Re: Wired Telephone Extension for 1.7 km

04/05/2008 6:12 PM

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

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Associate

Join Date: Jan 2008
Location: Kitchener, Ontario, Canada
Posts: 38
Good Answers: 1
#8
In reply to #7

Re: Wired Telephone Extension for 1.7 km

04/05/2008 8:05 PM

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

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Guru

Join Date: Aug 2005
Location: Hemel Hempstead, UK
Posts: 646
Good Answers: 11
#9

Re: Wired Telephone Extension for 1.7 km

04/07/2008 3:22 AM

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).

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Guru
United Kingdom - Member - New Member Engineering Fields - Instrumentation Engineering - New Member Fans of Old Computers - Vector 1 - New Member

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#10
In reply to #9

Re: Wired Telephone Extension for 1.7 km

04/07/2008 8:00 AM

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.

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Guru

Join Date: Aug 2005
Location: Hemel Hempstead, UK
Posts: 646
Good Answers: 11
#11
In reply to #10

Re: Wired Telephone Extension for 1.7 km

04/07/2008 9:11 AM

Good point!

I guess your signature line says it all--

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Guru
United Kingdom - Member - New Member Engineering Fields - Instrumentation Engineering - New Member Fans of Old Computers - Vector 1 - New Member

Join Date: Jul 2006
Location: Dunstable, England
Posts: 2480
Good Answers: 33
#12
In reply to #11

Re: Wired Telephone Extension for 1.7 km

04/07/2008 9:29 AM

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

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Posts: 14
#13
In reply to #9

Re: Wired Telephone Extension for 1.7 km

04/07/2008 12:49 PM

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

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Users who posted comments:

Asitha (1), Electroman (3), Guest (1), Hap (1), Jens (1), Magnacoaster (1), nelson1 (1), Randall (2), Redman46 (2), YWROADRUNNER (1)

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