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Author Topic: Remote powered modems  (Read 476 times)

Weaver

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Remote powered modems
« on: May 15, 2018, 05:35:16 AM »

Could a modem for DSL be designed that lives off dc power sent down the copper signal pairs?

There is 50V+ available already on the copper already. My fatherís elder sister, Auntie Gladys powered a great big fat mechanical bell-clanger off it, and in fact her son probably still does.

If you designed some safety system at the home NTE end to make sure in-house wiring such as extensions were separated off, and little fingers were kept out, perhaps you could increase the voltage a bit too? Just so long as you did not electrocute BT staff working in the field of course.
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j0hn

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Re: Remote powered modems
« Reply #1 on: May 15, 2018, 11:37:42 AM »

I believe 1 of OpenReach's G.Fast pilots included using DSLAMs powered by "reverse power". The DSLAM/pod would be positioned next to a DP, and the modems the DSLAM serves provide its power over twisted pairs.
Obviously this requires the modem to have "reverse power" also.

https://www.ispreview.co.uk/index.php/2017/06/bt-openreach-test-new-1gbps-broadband-pole-mounted-fttdp-g-fast-kit.html

I've never heard of a modem being powered by pairs, but if a DSLAM can be then it must be possible.
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Weaver

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Re: Remote powered modems
« Reply #2 on: May 15, 2018, 11:57:14 AM »

I meant the modems at the service provider end, not the CPE, I failed to explain that. I was thinking about the end user donating some Joules via DC to BT.
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jelv

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Re: Remote powered modems
« Reply #3 on: May 15, 2018, 02:45:52 PM »

I don't understand why anyone would want to do that even if it were possible!
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Weaver

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Re: Remote powered modems
« Reply #4 on: May 15, 2018, 03:06:58 PM »

I was reading about g.fast boxes that live in a manhole.

Some hw dev was demonstrating some such kit at a show iirc which could take dc from a load of individual domestic customers small current from each and lower voltage.
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