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Hardware

DSLBlaster? 139

Posted by michael from the turn-up-the-volume dept.
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.""
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DSLBlaster? More

DSLBlaster?

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  • Somthing similar (and different) was demonstrated by a company recently [and I have owned stock in it for years). http://www.nct-active.com/pr6_5_01.htm
  • True, though I would think that this is a good thing to have worked on, if only to provide a short-term fix when appropriate hardware isn't readily available. If you need your network connection, but if you can't get a new DSL or leased-line modem for several days, this would be a good thing to try.

    And no, I don't think it'd be a good idea to play quake on a machine that's doing this. It's something to be used on a router, IMHO.

    I had been curious about this sort of technology a year or so ago, but my math must have been off, and I figured it wouldn't work any better than a standard modem. I'm glad to see that other people had the same idea.
    --
  • How much does a DSL modem cost? 70, 80 bucks?

    You'd save like 20 bucks using a soundcard instead. what the hell's the point of this!?

    --
    Forget Napster. Why not really break the law?

  • From my point of view, the processor is a piece of generalized hardware.

    The idea of designing a processor and distributing the design freely has been around for a while. FPGA chips provide a possibility. Check out the OpenCores [opencores.org] project. Then there is the Transmeta [transmeta.com] approach of a very general core processor with surrounding software. Finally, emulators come in and out of vogue.

  • Pronounced "kuh roh five heen," kuro5hin [kuro5hin.org] is a weblog for the l33t. After all, if slashdot was l33t, it'd be named Slashd0t. Kuro5hin did not make a similar mistake by picking something inane like "kuroshin" as its name.
  • I've read the damn FAQ. Hell, I spend [kuro5hin.org] more time there than here. It's still pronounced "kuh roh five hin," and it's still l33t. More l33t than you anyway.
  • So does this mean we'll get a better connection if we use monster cable, just like the guy in the audio store tells us? :)

  • Ivan Sutherland's wheel of reincarnation ... (Score:4)

    by Stan Chesnutt ( 2253 ) on Wednesday June 06, 2001 @05:34PM (#170580) Homepage
    consult the Jargon Dictionary ... one link is:

    http://info.astrian.net/jargon/terms/w/wheel_of_ re incarnation.html

    The basic premise is that as CPUs become more powerful, that CPU assumes more of the tasks once relegated to special-purpose hardware. Then, somebody else notices that the CPU is doing "low-value" work, so the tasks move into dedicated silicon ...

  • Of course you completely ignored the various compression techniques in use today. Also you are assuming that 48KHZ is a 1 bit mono signal. However soundcards typically have a datarate of 48KHZ * 16-bits * 2 channels = 1.5Mbit / second . That comes pretty close to basic DSL. Taking into account modulation / error correction, that should still leave a sizable amount of IP bandwidth available...

    -adnans
  • You did something very cool. I love to see other people do stuff like this. Even in a place like Slashdot people can be so negative...

  • Say what? (Score:5)

    by Accipiter ( 8228 ) on Wednesday June 06, 2001 @03:27PM (#170583)
    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?

  • Actually, you wouldn't even need [slashdot.org] to pipe the flourescent light through your optical mouse.

    -Waldo
  • Do you have to use a leased line for this to work? Or could you possibly use this over a standard phone line?

  • Let's see... A typical stereo sound card has 2 A/D-D/A channels sampling at 44 kHz at 16 bits per sample. So that gives us 44,000*16*2 = 1.4 Mbps. Not too bad I think, but most likely in practice you'll get only a small fraction of this, quite possibly comparable to 128k ISDN or less on the average. A SB16 can only do full duplex with either the A/D running at 16 bits/sample and the D/A running at 8 bits/sample and vice-versa. And one of them will have to be restricted to mono. Which means maximum upload bandwidth will probably be less than a quarter of the download bandwidth, which is not too bad as for the average user, this is made up primarily of HTTP/GET requests :).

  • I've always been very skeptical of the claims surrounding the notion of transmitting data at high speed over power lines.

    Even if power line data transmission can do all they claim it can (which is doubtful given the reasons you've listed), there is still one fundamental problem to be overcome.

    The bandwidth will be shared. If it becomes popular, you're back in the same boat as a cable modem (and to a lesser extent DSL)... a slow connection with high latency.

    Bah. If they spent their money on research to make fiber optic lines cheaper to install, they'll be a lot more successful and would make more money.

    I mean, why don't they figure out how to trench in a cable more quickly and cheaply? Or how about some radar detection system that would warn you before you dug into a buried power line or water pipe? Or a badger-type robot that digs a hole and drags a cable behind it?

  • > What about running a network over old soundcards? Possible?

    With 100BaseTX NICs being available for $5 - $15, and 100BaseTX hubs being available for $25 - $35, I hardly think it would be practical.

  • Reminds me of a scheme I had... (Score:4)

    by Croaker ( 10633 ) on Wednesday June 06, 2001 @05:51PM (#170589)
    Hey, I already thought of this... sorta. I was thinking that you could hook two computers up over a phone line by using speech synthesis/recognition software. Think how much easier it would be to debug communications issues if you could understand what the computers were saying to each other by eavesdropping...

    computer 1: EA BF 02 51
    computer 2: Huh?
    computer 1: I *said* EA BF 02 51 36
    computer 2: Oh, yeah.
  • The other day. I wonder if this uses a regular phone line or if you need a dsl line....

    Question.. and think about this.. if ordinary modems work over ordinary phones lines why don't high speen modems also work over ordinary phone lines with no new switches??

    If you had any signal classes remeber that you have a carrier frequency and an actual signal .. What is the carrier frequency of a modem / phone line and why cannot a modem be made faster? DSL and phones use the same lines so where is the slowdown coming from?

    I don't want a lot, I just want it all!
    Flame away, I have a hose!

  • Because (Score:4)

    by Sloppy ( 14984 ) on Wednesday June 06, 2001 @05:42PM (#170591) Homepage Journal

    You're not supposed to ask why. Just chuckle and appreciate the Hack Value.


    ---
  • Reminds me of an old, crazy idea I had once...which would be to do a bus-topology network using sound cards.
    As sound cards don't have some sort of GUID like an ethernet hwaddr, one channel of the stereo sound cable would be used for constantly broadcasting the node's address, and the other used for data.
    Was never serious about it, but it was funny to think of...and now someone's actually DOING networking with audio cards!

  • I think it's good when anyone writes software that is useful for some purpose, even if it's completely proprietary, so I'm not saying that the AuDSL authors have done a bad thing, but I'd like point out that AuDSL is not currently free software, according to the "COPYRIGHT" file in their source distribution:

    5. Redistribution of the code as part of, or in association with, a hardware product specifically designed to perform data communications or audio signal signal processing by means of the code is prohibited without the specific prior written permission of Araneus Information Systems Oy.

    Also, if you want to go for compatability with the GNU General Public License, the Free Software Foundation claims that these sorts of advertising restrictions are GPL-incompatible (item 3 in the AuDSL COPYRIGHT file).

    If AuDSL were freed, I think their encoding implementations might be useful for the various free soft modem efforts, especially with the cheap Computer Telephony Integration risers available on some motherboards that basically connect the built-in AC97 sound hardware to the phone line. I also wonder if the techniques they use to get 96kbps might be usable to provide a "poor man's DSL," although I've heard that some semi-soft modem hardware that includes a Digital Signal Processor is theoretically capable of doing DSL, in which case there might not be anyone who would find this useful and rich enough to afford a premium phone service.

  • Wonder what would happen if one accidentally piped a BS MP3 through the sound blaster while it was connected to the line? Would the perky umm.. lyrics boost the line speed? :)
  • It is virtually impossible for ISPs to get inexpensive DSL modems in quantity. The ones that are 50-100 are usually PCI, which ISPs don't want to support. For some reason, the Ethernet ones (bridges and particularly routers) just aren't coming down in price despite their simplicity.

    Sure, it's one thing for a tech-head to go on eBay and get a modem for his or her DSL line cheap that may have seen a little use, but an ISP can't get 80 of them to sell to their users that way.

    -Chris
    ...More Powerful than Otto Preminger...
  • For that matter, why not use ethernet?

    I hear they've got ethernet cards which work at gigabit speeds. That's like, 100 megs a second!

    Even better, I hear the PCI bus is good for 132 megs a second. Let's just build a PCI to PCI bridge, with 10 miles of telco copper in the middle!

    It's digital. It must be better, right?

    Nevermind that the telco line won't carry the signal. Nevermind that it wouldn't carry SP/DIF, either. The shit is made for analog signals. It's -good- at carrying analog signals. Thus, analog signals are the order of the day.

    Gee, back to the drawing board.

    (think first, post later. k?)
  • actually, 16x2channelsx48khz. Closer to 1.5mbit :)

    but that's assuming (and usually, with optical ins/outs on good cards) that the card will do it...

    Heck, while we're at it, what about some of the higher end cards (96khz? or is it 92? I can't remember)...
  • 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.

    But you don't understand. If enough traditional, expensive leased line modems are made, then they will become inexpensive commodity PC hardware! :)
  • This sounds kinda cool, for those that are smart enough to use them. I feel sorry for the people who are gonna have to support it though, anything relying on the average end-users hardware is nuts to support, and anything that is software based (WINMODEMS!!! ACCKK!) is no doubt going to be installed and run on a bunch of p-133s by users who just dont have/want a clue. Then they'll bitch about it. Aside from that its a pretty good idea.

    What about running a network over old soundcards? Possible?

  • Sure they put DSL in the name, but they operate at 96kbps, or a bit less than twice modem speed wire. My little DSL line is pluggin along at 12 times that rate.

    That 96kbps is over a spool of wire. You can not get more than 64kbps through any POTS line that goes through the 8KHz, 8bit conversion in a digital telephone switching system. (If you think you can, then I suggest you find a more lucrative use for breaking the laws of mathematics.)

    Further, they make no mention of cross talk sensitivity or generation. Remember that in the US our modems are only 53kbps anyway because of frequency limitations.

    I give it an A for inspiration and a D for utility. The FCC will likely give it an F for violating power spectrum limitations on a phone line. (Putting DSL in the name was pure marketing genius! AuModem would never have gotten on slashdot)

  • Re:AuDSL is more modem than DSL (Score:4)

    by victim ( 30647 ) on Wednesday June 06, 2001 @08:49PM (#170601)
    Leased lines still have crosstalk and generate crosstalk. They run in the same bundles with all the other lines. They have the same restrictions on power spectrum as anything else in the bundle.

    They cost more (a LOT more where I am, not much more across the river from me) and they don't have the filters that make long analog phone lines more tolerable, but they still have all the crosstalk and noise problems of regular lines.

    You can run many models of DSL modems back-to-back over them. I don't do this, but you can read about it on the web then buy the modems cheap on ebay. (Might take a while to collect proper models.)

    In my experience leased lines have one unique property. Testing them fixes them. Your critical line goes out (several times a year in some cases), you call the carrier, they `test' the line, and then it works again. I suppose that helps their stats for the PSC.
  • Yes yes, I know. Its not funny. But I'm bored so I had to post SOMETHING. :)

    -Restil
  • A standard 56K modem will do them no good. They only listen at 56K. So, your still screwed.

    Not that there are not alternatives to this, but rather there isn't a commodity part they can use to do it.

  • Soundblaster for Sale (Score:3)

    by Cheesemaker ( 36551 ) on Wednesday June 06, 2001 @03:17PM (#170604) Journal
    For Sale: 10 aging "DSL modems" in my closet SoundBlaster brand...
  • It seems to be market specific. It seems that in some areas, cable modems and DSL modems can be had at the local $BIG_COMP_STORE, but in others, they are strictly handed out by the service provider.
    --
  • You don't use your hands, you use your....

    ...never mind, it's a guy thing.

  • 8 bits x 8KHz sampling rate = 64Kb/sec

    8 bits * 8kHz = 64kHz, not 64kbps.

    'bandwidth' is always misused in Comp Sci, it really is measured in Hz (or kHz/mHz), not in bits per second. And 8kHz will not necessarily result in 8kbps (it's not a 1Hz = 1bps relationship).
  • After all, how many /.ers have old 486 or Pentium machines running as firewalls/routers?

    I suspect that 486 does not have enough processing power to be a full G. Lite DSL modem (i.e. 1.5Mbps downstream). It's much, much easier routing ethernet packets than doing full handling of a DSL analog signal line at 1.5Mbps and routing...even if the routing was left to another system, I'll bet the modem, at full load, will take a considerable amount of CPU resources...(i.e. maybe too much for a 486).

    Maybe it will work...but especially since DSL modems are dropping fast in price I don't see this really being useful.

  • Re:Say what? (Score:5)

    by ddstreet ( 49825 ) <ddstreet@ieeOPENBSDe.org minus bsd> on Wednesday June 06, 2001 @03:59PM (#170609) Homepage
    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 [cisco.com] (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 $...
  • Right.. it probably has no real merit, but as a clever hack, this seems emminently doable. Sound cards are, after all, digital to analog converters (or analog to digital if you consider the line in), so it should be as doable as a modem is. And just as pointless as reinventing a modem. ;)

  • Soundcards with SP/DIF or Optical I/O are pretty common these days.

    Why would you use analog I/O at all?

    16bit samples at a 48khz sampling rate= 768Kbps which is pretty respectable.

  • Where's the (-1, Blatantly Wrong) moderation?

    Look at your units. You're multiplying bits by Hz (which are 1/seconds). That gets you bits/second, which is, incidentally, what bandwidth is.

    Perhaps this is why Physics tends to be a required course for Comp Sci majors...
    --

  • the end user can't just pick one up at CompukeSA

    actually last time I was in Compusa they had DSL modems on the shelf ....

  • Your so damned lucky.
    In the uk, for £50, that is probabley about $65 US you can ADSL, and it is capped at 512 down/ 256 up.

    And you are contractually forced to use a USB modem, that actually works more stable under windows, than any open Source OS, and is pretty crap under windows.

    Who would have thought that ADSL over Windows Dial Up networking was the best way to give your population ADSL?
  • If things are going to be done this way, couldn't they at LEAST use a PCI sound card?

    "Everything you know is wrong. (And stupid.)"

  • The solution is not always software (Score:5)

    by intuition ( 74209 ) on Wednesday June 06, 2001 @03:40PM (#170616) Homepage
    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.

  • sounds like idea of winmodem taken to extreme:-)

    now if somebody would make the sound card work like an ethernet card... etc... just like we have generic CPU we would have a generic input/output device... why bother with all the different hardware solutions?

    now excuse me, I have to go to nearest patent office:-)

    erik

  • Also, looking at a link from another post, it appears that ADSL is spec'd up to 1Mhz. A standard sound card just couldn't produce sound at those kind of frequencies, and it couldn't record / decode them either.

    The standard range for human hearing is around 20Hz to 20 kHz, so sound cards are optimised for sound close to this frequency range. The sound generator and sampler just wouldn't work at frequencies much above 20kHz, making any effort to use a standard sound card as part of an ADSL modem completely useless.

    Sound card manufacturers won't start making new sound cards that can generate and sample sound at those kind of frequencies because it's really expensive, difficult, and just plain pointless as it isn't sound and nobody can hear it. That doesn't even start taking into account the amount of CPU time needed to process the information and the amount of hassle wiring in hardware voltage / current level protectors and converters. I really think that this is a complete non-starter.

  • I mean seriously, what they are doing is using their souncard for a tradition modem.
    doh!
  • ...... now sound

    but

    no action:-)
  • The cards were designed for audio - they have filters which remove aliasing artefacts from the output. Sounds better, but it limits the high-frequency response (the filters don't have infinitely sharp cutoff) so the effective dynamic range is less than 16 bits. Also, the Shannon limit is only half the sampling rate, so even without filters you'd "only" be able to get 384 kb/s.
    --
  • So... could I get 6 times the speed using the 5.1 channels in via SPDIF that my SBLive supports?

    Better yet, hook up a line to one of the inputs on my stereo. Leave it on as white noise and figure out when the best time to download porn is by how quiet the other traffic is.
  • You can raise a kid with one parent but it shouldnt be done
    Sez who? Single parent child and PROUD OF IT!

    Buckets,

    pompomtom
  • A lot of comment-posters are missing the point. How much do you know about how DSL works? How much hands-on experimentation have you done with emulating hardware using barely-related hardware and some software?
    We make advances in technology because people either invent new technology or improve on existing technology. True, this is not an improvement on any kind of technology that we have right now. It's using a Sound Blaster and a very expensive CPU to create a DSL modem, whereas a 'real' DSL modem would give better performance for less money. But what this is, is someone learning a great deal about how something works and using that knowledge to build an unlikely device. DSL exists in the first place because some genius took the knowledge of how POTS works and realized a way to make use of the filtered-out bandwidth.
    This person was not trying to create something useful. He may tell you or even himself that he was, but in his heart he knows that he's just a hacker (true to the word, see previous paragraph) who is learning about the system. Who knows, maybe this augmented knowledge of DSL and broadband-over-analog technology in general will allow him to be a significant part of the next step upward in broadband. He certainly knows more than I do about how DSL works, and the same probably goes for the rest of us. Don't knock the guy because he's a hacker.
  • Here in new zealand you can by one from the providers if you want to waste some money.

    You get much better deals on DSL modems from the usual computer shops

  • nasty link

  • That gives me an idea! (Score:5)

    by Argy ( 95352 ) on Wednesday June 06, 2001 @04:33PM (#170627)
    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....
  • I had an idea once to make a very cheap coordless LAN. It's so simple it's stupid. You just hook up speakers and microphone on all the nodes and cover your ears. Sure you'll get some complaints from the neighbours, and it'll be hell trying to sleep at night while downloading pr0n/MP3s. But it's ultra-cheap and the ancient age of C64 will come back to you!

    Too bad it didn't work well because of feedback. LOUD feedback.

    - Steeltoe
  • Go ahead, moderate this a troll. I can take it.

    But seriously, why post this story? It's an utterly useless hardware hack which is tremendously behind the state of the art and (IMHO) doesn't even qualify as particularly creative.

    Using audio signals to transmit digital data!! Woohoo!! That's never been done before!! Now, the flourescent light network story was pretty interesting, and at least relatively novel, but this is pure drivel.

    If you read the tech specs, they're only getting 96Kb out of this thing, and it requires a leased line. Going through this amount of work to get twice the performance of an ordinary modem seems a bit ludicrous. What I'm amazed about is that they're only getting 96Kb -- I'm no signal expert, but that seems positively anemic given a 48KHz sampling rate. They're only getting two bits per sample?? WTF?? Truly pathetic next to my 1.5Mb DSL at home.

    This is news because... why, exactly?
  • Yeah, right. Signals down the power line. That's so far in the future that it's funny..."

    Actually, it's not. There are major consumer oriented installations of this technology going on in Germany right now, and there are companies that claim to have solved the problem with transformers, surges, ripple control, etc. Broadband down the power line will be feasible for many, many people sooner than you would think; certainly years before this sound card idea...

  • ... and I'm not sure I would call it broadband either.

    As it says at their site [araneus.fi], it is currently only able to reach speeds of 96 kbps. Why not use a modem instead?

    Other things worth noting: "Running on a 333 MHz AMD K6-2 processor, the software modem consumes about 38% of the CPU cycles." - Ouch. And that's on Linux. I wouldn't want to try something of the sort on Windoze with a few browser windows and an app or two open.

    Could this technology become interesting? Perhaps... maybe in three years when they have the bugs worked out and the code optimized, you can use it to get 256 kbps, maybe... Personally, I'm not planning on waiting that long!

    There are so many better solutions out there, and if you want my opinion, the real future of broadband is in the wire that is already running into your house. No, not the phone wire. This one [business2.com]. Now serving over 90% of the world's population...

  • Im sure your proud you didnt need a another parent, but if we asked your kid I bet they would vote differnt. Maybe the wouldnt choose the person you decided to get drunk with that one night, but Im sure they have a mental picture of the person other person they would like to be related to. If they dont Im sorry you warped your kid that much. The only good thing is that your warped kid will have trouble having kids as well, and well we know where that goes, you loose, darwin wins ^H^H^H^H^H^H We win.

  • nutz (Score:5)

    by sPaKr ( 116314 ) on Wednesday June 06, 2001 @03:38PM (#170633)
    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 quite...

    Shannon had a couple of good theorems, but the one you're talking about is courtesy of Nyquist. To have any chance of recovering sampled data, the sampling rate must be at least twice the highest frequency content of the original, analog signal. The original poster's calculation (16 bits/sample * 48 ksamples/sec) was right, but it assumes a noiseless channel.

    Shannon's noisy channel theorem is probably more applicable. (the heorem's result is likely what he meant by "Shannon's limit.") Shannon said that a channel's capacity in bps equals channel bandwidth(Hz) * log2(SNR+1). A classic example is the plain old telephone system. The bandwidth allowed is about 3kHz (300Hz - 3.3kHz). The SNR the telcos try to maintain is around 35db, or about 3100. This gives a maximum reliable capacity of around 35kbps.

    One fun side note: the 3khz bandwidth limit is not an inherant limitation of the copper telephone lines. It's actually the frequency range chosen as sufficient for voice communication by none other than Alexander Graham Bell. His original equipment used this 3khz bandwidth, and all subsequent telephone equipment adhered to the same standard. Though it was made more than 150 years ago, his choice for bandwidth stuck (and is the reason many of us *still* can't get DSL connections to our homes!).

  • A couple of Speakers and mics, and you could have a cheap wireless network!(though, the noise may drive you a little nuts).

  • Not that impressive (Score:5)

    by Animats ( 122034 ) on Wednesday June 06, 2001 @04:14PM (#170636) Homepage
    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.
  • How do they connect .?

  • yeah but if youre not thinking practicality here and decide .. well this would be a neat idea.. would it be possible?

  • You know, I was just thinking...whatever happened to the days when geeks would look at something like this, useful or otherwise, and say "cool!"

  • this [slashdot.org] would be considered a troll, when this story [slashdot.org] is what insited the argument to begin with.

    I suggest people better understand the sources for others frustration before being so quick and naive to judge.

    also amusing is that the moderater didn't even leave a comment as to why. Interesting that on Kuro5hin, one is held accountable [kuro5hin.org] for their actions.

  • Yeah, maybe it's only slightly faster than conventional dial-up. Yeah, maybe it defeats the purpose of true DSL. That's not the point: this is a cooooool hack. DSL implemented in software?! Kudos, guys.

    In NZ, we can subscribe to bandwidth choked flat-rate DSL. The only preventative measure is the modem cost (which is significant compared to the relatively small benefit of the crippled-DSL service). However, for people with the modems already, it's great. Now, if I can plug my box into my DSL line through my soundcard (sitting dormant in the case), I'm very happy.

    Sure, this won't stop most people from going the whole DSL hog, but it's a damn fine hack that shows geek ingenuity at it's best.

    --

  • He died on July 6th, not June 6th.

    Oh, and you were 30 years too late, AC.
  • Sounds like a good idea but I hope they do a better job than the software modems/printers (WinModems...) that we all think are terrible. But would it tie up my sound card? What good is DSL if I can't listen to the MP3s I download?
  • Whole bunch of info on the Web site. 96kbps. It's not for the faint of heart to build and won't be speedy, but it's a nice grassroots thing...

    If it weren't June, I'd take it for an Aprils Fool, but at a cursory glance it does look like the guy actually built it. It would be cool in areas where copper is available, but ADSL gear is out because of the distances.

  • Can you go to a clue store and buy one? Please? Stop whining. The chances are, you won't ever use this or see it in use. The main points are a) the hack value and b) your friend's a retard. It doesn't take a genius to setup an ethernet connection. It's one thing not to be able to set one up, thats perfectly fine. But to say someone who is "very capable in setting up and tweaking his DSL setup" obviously does not refer to one's knowledge of an operating system.
  • Almost spit out my tea when I read this one. Yes, yes, I can picture the people in cube farms covering the ears right now.
  • My athlon doubles as an electric burner. . .

  • Why? (Score:5)

    by Once&FutureRocketman ( 148585 ) <otvk4o702@@@sneakemail...com> on Wednesday June 06, 2001 @03:35PM (#170648) Homepage
    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.

  • (8 bits / sample) * (8000 samples / second) = 64000 bits / second

    This is the sampling rate/depth used for voice telephone lines by the telephone company.

    Cryptnotic

  • Actually, Shannon's theorem states (if I recall correctly) that the maximum input signal can only be HALF of the sampling rate. (or that the sampling rate needs to be twice the maximum input signal). So the input rate used needs to be only 24000Hz to be recognizable by the sound card without extra synchronization. 24000Hz (samples / second) * 16 bits / sample = 38400 bits / second.

    Cryptnotic

  • Ah, Nyquist's theorem. You are correct, that is what I was thinking of.

    Cryptnotic

  • The POINT was to build a better way to transfer MP3's to the hard drive in my car's mp3 player-

    Why can't you use wireless ethernet?

  • Actually, it may make sense. Currently at this early alpha stage they're already getting 96Kbps... I would expect that to increase as future versions allow. I bet this could eventually be a viable option for some people. I wouldn't disparage the use of acoustic signals just because they are acoustic signals-- the end result is all that matters! If they can do it, Bravo!!
  • The slowdown comes from the fact that they *dont* use the same lines, exactly. Sure, it's the same copper - but for starters, a voice-grade line has this nice little filter that lops off everything over 4Khz. Remember that the *original* use of a T-1 line at 1.544mbits/second was to carry 24 voice lines. To get them to fit, the telco would lop it off at 4khz (which is why a phone call doesn't sound "in person"). That frequency was chosen as a good compromise between bandwidth utilization and reproduction *human voice*.

    A DSL line gets its speed mostly by virtue of not having to fit the bits through a 4khz filter. Shannon tells us that 33.6 is about the limit for a 4kz signal - 56K modems actually cheat (hint - *every* computer store stocks the "consumer" end of a 56K modem - ever tried to buy the *uplink* end of the pair, and provisioned the line from the telco? ;) Also, there's no pesky power restrictions - those enter into it because the power determines just how close to a perfect square wave youy can get (since the power is basically the slope of the near-vertical parts of the waveform).

  • The idea is to replace traditional, expensive leased line modems with software modems running on PCs...

    Just what we need, another round of WinModems. DSL is hard enough to get working in Linux. My friend, who is very capable in setting up and tweaking his DSL setup, spent three months of trial and error getting his DSL connection working with Linux. The last thing we need is a software modem to make it even worse.

  • In place of my cable modem, I'll hook the cable into my television set. It'll show a scribbly image
    nah most places it will just show normal cable tv..
  • A while back, I attempted to scrape together a wireless ethernet connection of SOME type out of some modems and a couple of cheap-O walkie Talkies...

    Needless to say, it was a TOTAL flop. The walkie talkie transfer was garbled beyond recognition and I couldn't even connect the two points at 300bps. (I seriously have to question whether it would have worked at all to start with though- I'm not a genius with funky software hacks, but I know enough to hang myself with...)

    The POINT was to build a better way to transfer MP3's to the hard drive in my car's mp3 player--yah- one more keen ornamental hack, but it would be much nicer to do it that way than physically either lug the whole unit in or string a frikkin LONG cable all the way out to the garage...

    So I'm thinking this sound based hack PLUS a couple of those high tech mini-fm 2 way radios that seem to be everywhere now, and this just might work!
    Anyone else been down this road?
  • 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

    I guess the idea is that if you have spare CPU cycles, the everything is fine.

    Myself, I prefer dedicated hardware.

    Check out the Vinny the Vampire [eplugz.com] comic strip

  • 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

    No kidding. You forgot noise.

    Just because you slap 16 bit D/A/D gear on the ends of the wire doesn't mean you're going to get 16 bits per symbol through it, sweetie. Hell, why not use 32 bits? 128? The sky's the limit!

    Shannon also says that you have to divide in the noise level to figure out how many bits you can get per symbol. THEN you design your D/A/D gear to suit. Dialup PC analog phone modems use 2400 symbols per sec x 14 bits per symbol for 33.6 kbps -- 2400 Hz because of the phone system audio sampling rate and 14 bits/symbols because of the expected noise floor and maximum allowed signal power (FCC limit). 56 kbps cheats the noise floor down a bit but I won't go into that.

    Now, *IF* you've got a LEASED LINE that you can dump massive signal power onto (i.e. no other equipment on line), and you've got low inter-symbol interference (ISI - think of it as a time smear of the symbols), then hell yeah you can get 768 kbps. And I'd drive 130 MPH to work if it wasn't for those pesky cops (and curves).

  • When will they tell me I can use my PC speaker for a T1?
  • 1) Transformers. They furk the signal up completely. You can't get a signal 'upstream' from a transformer any faster than 9600 bits/sec.

    That might be true for the smaller Decepticons like Rumble & Frenzy, but a larger one customized for data transmission (Soundwave, for instance) can probably handle bandwidth similar to a fiber bundle.

  • I wonder what speeds could be achieved over a radio link. I have a few good friends that are hams, and we are always complaining about the fact that we are 20 miles apart without line of sight, which rules out the possibility of a high speed link. We talk over voice links all the time, but the fastest we can get without line of sight with of the shelf hardware is 9600 baud(38400 if we could get ahold of some data radios). The problem is that for each packet the transmitter has to be keyed up, sends a preamble, then sends a IP packet wrapped in a fake AX25 header. Sure, these are the links that TCP/IP was designed for, but we have come along way since then. The only time I have seen people play Q3 over ham radio(A wonderful use of our spectrum) was over microwave links. I know 56k/78k equipment does exist, but I don't feel like shelling out 800 bucks at each end for those speeds.
  • I believe the first "winmodem" was on the Commodore 64. :) The first modem for that computer had to use a chunk of memory and processor to do anything, it wasn't an independent device.

  • Re:nutz (Score:3)

    by tswinzig ( 210999 ) on Wednesday June 06, 2001 @07:36PM (#170667) Journal
    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

    How DO you reach the pedals with your hands?
  • uh no, your wrong. look at the faq, you're wrong on two points:
    Where does Kuro5hin.org get its name? (Go To Top) No, it is most decidedly not 'l337. It is a pun on Rusty's name. Kuro5hin == corrosion == rust == rusty.
    look here---> Kuro5hin origin [kuro5hin.org]

  • Who even thought up this winmodem stuff anyway? In an age where we offload everything for greater performance (3d accelerators, TV cards, mp3 capable sound cards, etc) we are reversing the process with modems. Gee, all that CPU you saved by offloading your 3D rendering to a separate card has just gone to your software modem. Isn't that ludicrous? What loon came up with this idea?
  • I think people are missing the point here.

    They aren't trying to do this over a PSTN (regular phone lines) - they are trying to make use of a dedicated, leased line for which the modems are a lot more expensive than a plain DSL hookup.

  • They aren't using phone lines - they are using leased lines which is a whole 'nuther kettle of fish. The FCC won't be complaining to them. Leased line modems ARE expensive.

  • My theory is that they are so snowed in for most of the year they sit in front of PC's and code. This is just cool.
    --

  • . . .but I'm not entirely convinced of it's feasability.

    Let me explain.

    Using audio to transfer data isn't a new idea. The humble telephone line modem bears witness to that, as does modern DSL.

    What is new about this is the really creative hardware hack. Sound cards (like any other expansion card) are manufactured with a purpose in mind (in this case, that purpose is producing or inputting sound). With the exception of some cards produced with a modem input, these adapters may not be designed in such a way to enable data transfer.

    That would have to be addressed in software. To make this method widely-used, AuDSL would need to include modified drivers for common sound cards in addition to the software instructions that tell your computer how to take this audio data and turn it into something usable.

    And then there's the matter of it taking 38% of CPU cycles. . .

    A better solution might be to design a less expensive alternative to already existing hardware that would work with already existing systems.

    I admire their ingenuity, but I wonder if there isn't a better way. . .

  • I think everyone is missing the true coolness here. Using software + generic hardware to simulate specialized hardware might sound like a bad tradeoff at first, but consider: the processor is just one more piece of specialized hardware, right?

    So all we need to do is encourage this trend until we get to the point where someone figures out a way to simulate the processor with software and Presto! computers cost nothing to replicate, generate no heat, and can be shared over Napster.

    -- MarkusQ

    Next week: How to legally avoid paying taxes without having to earn any money.

  • Re:Interesting, but I wouldn't want it... (Score:4)

    by af200xl ( 458104 ) on Wednesday June 06, 2001 @05:00PM (#170707)
    Yeah, right. Signals down the power line. That's so far in the future that it's funny, Trust me. I was invloved in a full-on pilot of this in Wellington, New Zealand, and while it works fine over short distances, there are a number of major issues yet to be overcome.

    1) Transformers. They furk the signal up completely. You can't get a signal 'upstream' from a transformer any faster than 9600 bits/sec.
    2) Ripple control - the signals that the power co's use to trip multi-register meters (like day/night meters or 1/2 hourly meters etc) When the pulses go down the line, the signal is completely porked.
    3) Surges. Not flash for signal quality, to say the least
    4) Loop length. Even without pesky transformers etc, the signal gets pretty weak at > 5 km (3 miles)... although the same can be said for DSL.
    5) The kind of wire that is used in the electricity cable is optimised for conducting high to medium voltages so frequencies that can be used are limited, limiting bandwidth for concurrent users.

    However! Most of these things can be overcome... in time. The problem is, the technology will only be useful if the power line folks can match the prices for telephone lines, with the same speed and reliability. Right now I get between 4 and 5 Mbps for around $30 US per month via ADSL. Power lines are gonna take a really long time to match that.

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