DSLBlaster?

The Jake writes: "Here's some mindless link propagation for you, Kuro5hin style. Memepool reports that AuDSL will let you use an old sound card to connect to a subscriber line. "AuDSL is an experimental technology for achieving low-cost leased-line Internet connectivity for homes and small businesses. The acronym AuDSL stands for Audio Digital Subscriber Line. The idea is to replace traditional, expensive leased line modems with software modems running on PCs, connecting the leased line to an ordinary PC sound card. This makes it possible to construct a complete leased line internet gateway entirely from inexpensive commodity PC hardware.""

Comments

Say what?

[Accipiter]

This doesn't make a whole lot of sense.

The idea behind DSL was to eliminate the usage of acoustic signals for data transfer. By modulating the DSL signal into an audio stream, you're defeating the purpose.

Sound cards aren't even designed for this sort of thing. The same limitations that hit Winmodems will apply here as well, and will be multiplied. There's going to be some serious CPU usage (which could eventually be partially alleviated by the DSP development) because you still have to modulate/demodulate the DSL signal from audio to data. Not only that, but a specialized circuit must be built to even do this.

I would assume the low cost wouldn't be a factor due to the hassle, and the functionality.

This type of connection will yield slightly-faster-than-Dial-Up speeds at DSL prices. How does that constitute "Low Cost"?

-- Give him Head? Be a Beacon?

Re:Say what?

[ddstreet]

The idea behind DSL was to eliminate the usage of acoustic signals for data transfer. By modulating the DSL signal into an audio stream, you're defeating the purpose.

On the contrary, that was not the idea behind DSL. A telephone line is a single Unshielded Twisted Pair (UTP) of wires, of which only the first 4kHz is used (for voice transmission). The bandwidth (true bandwidth, measured in Hz not bits per second) of the line is much wider than 4kHz so DSL puts analog signals in the unused freuquencies. On each end (telco and user), there is a D/A and A/D converter that handles this translation. The signal on the phone line is an analog signal, not digital. See this diagram (and the rest of that document) for a somewhat better explanation of xDSL.

So turning a sound card into a DSL modem saves $ of the DSL modem (the sound card does the D/A and A/D and the CPU handles 'talking' to the other DSL modem). But I agree with you that it's basically becoming a 'Winmodem' where the CPU usage will shoot up to (IMHO) unacceptable levels. DSL modems aren't that much $...

The solution is not always software

[intuition]

Although it is true that some things can be implemented cheaper in software, this is not necessarily true all the time. (And of course cheaper != better)

Is our future generic appliances that can upon downloading the latest software release do whatever we please. Although this would be nice, it is hardly realistic. It flies in the face of years and years of solid task-appropriate engineering.

Furthermore, I don't know anyone who doesn't have DSL because of the price of the damn DSL modem. Its like not having nike's because you can't afford to be replacing the shoe laces.

Software is great for implementing more niche-market type appliances (remember firewalls in the early days.) But the limitations and unnecessary over head of generic solutions will eventually give way to well-engineered solution-specific devices.

I thought winmodems were a thing of the past, but it seems someone is trying to reincarnate them in the DSL flavor. I am sure they will find the limitations of the sound cards a huge-tradeoff for the supposed money savings.

That gives me an idea!

[Argy]

In place of my cable modem, I'll hook the cable into my television set. It'll show a scribbly image, but the TV's radiation will minutely interfere with my fluorescent light. By reprogramming the DSP inside my optical mouse and holding it up to the bulb, I'll have a steady stream of data coming through the mouse's USB connector. From there, it's a simple matter of hooking the mouse to my Laserjet's USB port, changing the ROM to redirect the packets out the parallel input port, running that to my Xircom parallel port ethernet adapter, and from there straight into my 10 base-T hub.

Now if I can just think of a way to get from the hub to my computer....

nutz

[sPaKr]

You can raise a kid with one parent but it shouldnt be done
You can drive a car with your feet but it shouldnt be done
You can fertalize you lawn with used motor oil but it shouldnt be done
And now you can build a DSL modem out of a soundcard but it shouldnt be done

Not that impressive

[Animats]

They ought to be able to do much better given a solid copper pair, 16-bit D/A and A/D, and a 48KHz sampling rate. The Shannon limit for that setup is 48000*16 bits/sec, or 768 Kb/s. That's under optimal conditions, but ordinary modems routinely get 80% of the Shannon limit for their medium (8 bits x 8KHz sampling rate = 64Kb/sec) The line has to be characterized during startup and appropriate equalization applied, but that's a well-understood process built into every modem.

Why?

[Once&FutureRocketman]

This smells like a solution looking for a problem. Or more accurately, it's a solution that does not match the problem that actually exists.

ADSL modems (at least; don't know about SDSL) aren't actually that expensive. They can be had (used) for $50-$100 if you do a little looking. They're aren't very complicated devices. The reason they cost alot is that the manufacturers currently are only supposed to sell to DSL providers: the end user can't just pick one up at CompukeSA, so the providers charge what they want.

So what I don't understand is, why would the providers ever go for something like this?

Oh yeah, and don't even think about netgaming on this system. Soundblasters have a bad habit of taking over the PCI bus as it is. I can't imagine this making it anything but worse.