HFU HF Underground
Technical Topics => Part 15 AM and FM Station Operation => Topic started by: ThaDood on May 28, 2025, 1806 UTC
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Ya know... A friend of mine struck on a subject that I've wanted to explore for a while now, a free Carrier-Current Coupling Unit for the AM Broadcast Band. And, you might just have one already. When a DSL MODEM is done with use, don't trash it, but cob it for parts, like that built-in coupler for Carrier-Current to the phone lines. You'd think that would be good for a few watts. And, not HOT inject, but Neutral inject. Hey... The price is right, and everyone usually just trashes these. Certainly, worth looking into. I have yet to try this myself, but had contemplated on the idea for a while now. So, if y'all out there got the time to open one of these units up and cob the coupler units, I'd like to hear the results.
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Carrier-Current to the phone lines?
What exactly do you mean?
In any case, sounds intriguing.
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Some key excerpts from https://www.blackbox.com/insights/blackbox-explains/inner/detail/networking/connectivity/what-is-a-dsl-modem
What is a DSL modem?
A DSL "modem" is a baseband modem (MOdulator/DEModulator) that delivers high-speed communication for short-distance interconnection or last-mile access. A DSL modem uses special coding techniques to get maximum throughput from the low bandwidth of voice-grade copper wire. At either end of the copper phone line (also known as "twisted copper pairs"), a DSL modem is installed. By adding ordinary telephone splitter boxes, the line can handle simultaneous voice connections.
Asymmetric DSL (ADSL)
..... provides asymmetric transmission over one pair of copper telephone wires, and it allows the telephone line to be used simultaneously for voice and data transmission.
Integrated DSL (IDSL)
... to deliver transmission speeds from 64 kbps up to 144 kbps. It allows for extended distances.. ... it is a dedicated service for data communications only.
Multi-rate symmetric DSL (MSDSL)
... operates at a variety of rates, ... to enable service providers to offer increased flexibility to their customers.
High-bit-rate DSL (HDSL)
High-bit-rate DSL is similar to SDSL and has symmetrical transmission capabilities. Most E1 lines installed today use this technology.
High-bit-rate DSL 2 (HDSL2)
. ...uses only a single twisted copper pair. This is a distinct advantage in certain areas where unused copper pairs are becoming rare. HDSL2 is currently being developed as an industry standard.
Rate-Adaptive Asymmetric DSL (RADSL)
... rate is automatically adjusted to optimise the signal quality under the line condition.
Very high-bit-rate DSL (VDSL)
... very-high-bit-rate DSL, delivers high bandwidth over an existing single pair of copper wires. VDSL is the highest-speed technology in the XDSL family.
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Hey Tybee... Interesting DSL INFO. However, no INFO upon what FREQ(s) are used to do it RF-wise. So, ever notice when you are trying to listen to an AM station, from like 1,000kHz to even near the 160M Amateur Band, and get an earful of digital hash on some FREQ's? Apparently, Medium Wave is where DSL is modulated upon. One of those FREQ's happened to be 1620kHz here. Now, Verizon tries to cram DSL to reach up to like 3 miles. They may have relay booster points as well to get even further. So, if DSL is trying to get that kind of usable range, via a Carrier-Current technique, then it would seem logical that the couplers in the trashed DSL MODEM's could make for some usable, free, Carrier-Current Couplers for our use. Thus, why I'm contemplating upon this idea.
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DSL (Digital Subscriber Line) uses specific frequency bands for data transmission and voice communication. Data transmission occurs at higher frequencies (25 kHz and above), while voice communication uses lower frequencies (4 kHz and below). This separation allows for both services to share the same copper phone line without interference.
That's what google ai told me.
... So, if DSL is trying to get that kind of usable range, via a Carrier-Current technique, then it would seem logical that the couplers in the trashed DSL MODEM's could make for some usable, free, Carrier-Current Couplers for our use. Thus, why I'm contemplating upon this idea.
I think the idea sounds intriguing as hell, it would be a super cool re-use of the modems, there must be thousands of old used ones out there that could be picked up for pennies