Using a wireless phone 160ft underground?

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Discussion Overview

The discussion revolves around the feasibility of using a wireless phone in an underground cavern of a non-operational mine, specifically focusing on the technical challenges and potential solutions for maintaining connectivity over a distance of 2000 feet using a network cable and antennas.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about using a wireless portable phone with antennas at both ends of a Cat5e cable to transmit signals underground.
  • Another participant points out that Cat5e cable is limited to 100 MHz and suggests that using it for DECT 6 signals at 1.9 GHz would result in significant signal loss.
  • A different participant proposes placing the base unit in the mine to reduce signal loss, as the cable would handle audio signals better than high-frequency signals.
  • One participant suggests the possibility of using an extra base unit in the mine connected to the landline output of the above-ground base unit.
  • Another participant proposes using a Wi-Fi-based system connected by a wired Ethernet link, referring to it as a Voice over Internet Protocol (VoIP) solution.
  • One participant questions the applicability of a cellular repeater for the setup, later clarifying that the original inquiry is about a cordless phone system.

Areas of Agreement / Disagreement

Participants express differing views on the best approach to achieve wireless communication underground, with no consensus reached on a single solution. Some suggest alternative setups while others highlight technical limitations of the proposed methods.

Contextual Notes

There are limitations regarding the frequency response of Cat5e cable and the operational constraints of the existing phone system, which may affect the feasibility of the proposed solutions.

newmark789
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Hello all, I'm not all that savvy with radio antennas, or physics in general, so I've come to kindly ask for your expertise in solving a problem that I'm working on.

Basically, I'm looking for a relatively simple way to get a wireless portable phone to work in an underground cavern of a small non operational mine. The decline ramp into the mine is roughly 2000ft long with a line of cat5e magnetically shielded network cable along the run. At the surface is the wireless base station. I'm wanting to use the network cable with antennas on each end to carry the signal. Is this possible to essentially have the underground portable phone wirelessly transmit to the underground end of the cable then travel 2000ft (vertical distance from surface is 160ft) to an antenna that is situated right next to the base station where it is relayed to it? Any one able to speculate on what kind of components I'd need? Do I need to amplify the signal in such a case? It may also be possible to wire the phone into the cord

The phone system uses the Dect 6 standard if that is of any assistance.

Thank you again if anyone is able to share their knowledge.

Cheers!
 
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You don't say which country you're writing from so I will assume the United States. Cat5e cable is limited to 100 MHz and even then not for lengths of 2000 ft. In the U.S. cordless phones using DECT 6 operate at 1.9 GHz. Cat5e cable at 1.9 GHz would have so much loss the signal wouldn't go very far.

Why couldn't you put the base unit in the mine also and connect the base's phone connection to the cat5e cable? The cable will have orders of magnitude less loss at audio than at 1.9 GHz. Also the phone base unit will be feeding many orders of magnitude more signal into the cable than will an antenna.
 
Hi, I'm actually in Canada, but the standards are the same I believe.

I can't put the base unit in the mine because it serves other wireless extensions above ground. I may just have to set it up as a separate land line it looks like. Thanks for your input though :)
 
I've never tried this or even heard of it being done, but couldn't you get an extra base unit for down in the mine and wire the land line output as an extension of the base unit above ground?
 
How about a WI FI based system above and below ground, connected by a wired ethernet link? The system is referred to as SIP and you use it just like a telephone system - dialling in and out transparently. Voice over Internet Protocol. It could be a turnkey project for you.
 
Would a http://en.wikipedia.org/wiki/Cellular_repeater" work in this case?

Edit: I misread. You're not using a cell phone. Maybe they have something similar that would work with this cordless phone setup?
 
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