r/electronics • u/gaspar_segura • 2d ago
Gallery Took some pics of an ADSL modem/router. There are some interesting networks/components on the PCB.
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u/TheRealFailtester 1d ago edited 1d ago
I wonder if there are devices made for making use of these things after they are decommissioned.
Such as a gizmo that would take in an ethernet connection, bridge it to ADSL, that goes down an ordinary POTS line, and then goes through the ADSL modem to the be bridged to ethernet, wifi, etc.
There are things that do this called Ethernet Extenders, but it's proprietary to between the manufacturer's specific devices.
Edit: It would also be awesome to do such a thing with DOCSIS, something to revive some 1.0, 1.1, 2.0, etc. old era modems for the fun of it within a LAN.
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u/Inuyasha-rules 1d ago
Some can have their firmware flashed to be used as a standalone router, but not many. I don't think they can generate the required signaling to do extension over the dsl interface. What's weird to me is they used an external mediatek chip to generate the WiFi, when the main mediatek CPU has WiFi built in, and they provided traces for both options on the same board.
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u/Annon201 2h ago
Maybe a second SoC to provide an ISP controlled access point? (Like Telstra in Australia did, piggybacking of their customers to provide a a network of member-accessable access points)
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u/TheMM94 1d ago
I worked with some industrial SHDSL modems which could work as both LT (line termination = the device used by the ISP for the DSL line) and NT (network termination = the device used by the customer for DSL). With this devices you could send data over POTS, with only a modem on both sides.
But, I'm not sure if the ADSL chipset used for normal consumer modems would support this. I suspect they would only support the NT mode. Also, the chipsets often have proprietary driver/firmware, which you can only get from the chipset manufacturer under NDA.
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u/BitEater-32168 1d ago
No, not with the adsl chips. But most of the sdsl modem/routers i had could be configured to be cpe or co.
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u/NotAnotherNekopan 13h ago
My friend did this as a hack to get Ethernet extended in a large building with only POTS lines and very little options / money.
We found a recycled DSLAM and hooked it up.
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u/TheRealFailtester 12h ago
Yeah it appears that is what I would need.
I get wind that I would need a cable modem termination system to properly repurpose retired consumer end docsis modems.
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u/NotAnotherNekopan 11h ago edited 11h ago
Those are a lot tougher to come by. And, if you’re doing this solely for the purpose of reusing existing coax cabling, you might as well just use MoCA. Its purpose designed for the task. Any CMTS unit is going to be huge, power hungry, and loud.
I have also built out a complete lab that had POTS, dial-up (300 baud to proper 56k), ISDN BRI and PRI, and ADSL. I’ve since scrapped the project, I don’t have the space anymore, but it was fun.
I never found a reasonable way to integrate DOCSIS. That being said, projects that utilize SDRs like the LimeSDR could theoretically emulate that protocol. At some point I’ll be building out an AMPS network using a LimeSDR mini and OSMOCOM-analog so I can actually use my IBM Simon to send/receive real phone calls and faxes.
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u/TheRealFailtester 10h ago edited 10h ago
Indeed MOCA would be more user friendly, my docsis idea is to give some life back to some 2000s era cable modems solely for the fun of it. Issue is it looks like doing so is not going to be an easy task.
I found these gizmos: https://www.alibaba.com/product-detail/_60521635271.html (I have no idea if that website is safe or not.) has some docsis 2.0 gizmos that show they bridge ethernet into docsis 2.0 back and forth- but I start to assume that it's still going to be proprietary to just those devices and will refuse to talk to another modem that isn't from that manufacturer. But not sure I've not got any to try it out.
As that is what I ran into with some VDSL2 ethernet extenders from Star Tech, they send a VDSL2 signal between each other, but if I plugged in another VDSL2 modem that I had laying around, it would start training, look all good, and right about 90% completed initiating a connection, then it would bootloop, and repeat infinitely. I assume I may run into that kind of issue if I were to obtain those docsis 2.0 gizmos, and then try sending one of them to a old 2000s era doscis 2.0 modem that is from an old ISP.
Edit: And even if those were to work seamlessly for most any 2.0 modem, well that does not cover a lot of the old modems I encounter, I still find quite a few 1.0 and 1.1 modems.
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u/Inuyasha-rules 7h ago
Some satellite TV multiplexors can send out a docsis signal. I have no idea about configuration, that's all handled by our vendor. If I get a chance to get into the equipment room, I'll post a link of what hardware we are using. These are commonly used in hotels and hospitals to distribute TV to the rooms, and if you're lucky, you can get them during an upgrade.
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u/dreamsxyz 1d ago
Reusing them as communication devices outside of their scope in service providers would be super cool. Let us know if you learn about any similar project.
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u/r4pt0r 1d ago
Why did they put silkscreen over the trace where it comes out of the shield?
Does this serve any electrical benefit?