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Why 56k is the fastest dial up modem speed
- davidmurdoch 3y ago[flagged]
- laserlight 3y agoDid you mean: Why HN screw with titles? PS: Title as of this comment is “Why 56k the fastest dial up modem speed”
- cantSpellSober 3y agoThe "is" is missing from the title (Why is 56k). I wish HN just autofilled the Title field after the URL field has changed during submission (but still allowed users to edit the title).
- HPsquared 3y agoReally it would look better if they removed the "the" too. Newspapers often leave out that kind of thing. (Not that newspapers are the best role models)
- cantSpellSober 3y agoYep, "Pearl Harbor Bombed" for example. Or when Colbert mockingly summarized It was the best of times, as "Dickens: Times Best!" https://www.cc.com/video/coii6k/the-colbert-report-cable-news-gaffe-on-obamacare-supreme-court-ruling https://www.cc.com/video/coii6k/the-colbert-report-cable-new...
- deleted 3y ago[deleted]
- tom_ 3y agoI assume whoever typed it in just missed a word.
- swayvil 3y agoBecause with the power to control us comes the feeling that they should control us.
- deleted 3y ago[deleted]
- TonyTrapp 3y agoTIL: Phone networks already carried digital signals in the 60s. I absolutely did not expect that.
- p3n1s 3y ago"Fast-forward to 1962. Ma Bell begins using T-1s to connect its switching centers. T-1s are a digital communications link, not analog. The entire phone network goes digital. In a modern phone network, the only analog communication is between an individual house's phone line and the phone company's box." This is misleading. The phone network used analog links (typically microwave relay) for long distance almost exclusively for many years (into the 80s) after the introduction of T1. T1 itself is not terribly well suited to very long distance links though and can only be pressed into it with repeaters every mile or so.
- throwaway167 3y agoHence towers with dishes on the outside. Long perplexed why they had canvas stretched across, and didn't point up: https://en.m.wikipedia.org/wiki/Microwave#/media/File%3AFrazier_Peak%2C_tower_and_Honda_Element.jpg https://en.m.wikipedia.org/wiki/Microwave#/media/File%3AFraz...
- jjjjmoney 3y agoOur Charter Spectrum “cable” connection goes over a microwave link like this. How do I know? Well, we had a pretty big wildfire a couple years ago that burned a microwave tower a couple hours away. The official response was that they couldn’t get internet back in town until they rebuilt the tower. Our internet was down for a couple weeks until it was safe enough for them to get back to the tower site.
- Sharlin 3y agoMicrowave relay links predate spaceflight and even when comms satellites became a thing, it made (and still makes) little sense to beam regional TV/radio/phone up to geosynchronous and back, due to cost and latency. There was no good replacement to terrestrial microwave until fiber optic became a thing. In a very real sense microwave relays are the direct descendant of the optical telegraph (aka "clacks" in Discworld lingo).
- bwann 3y agoTo nitpick, the 53.3k limit only affected US Robotics' pre-V.90 standard called X2, due to how much power they would require, which violated FCC rules. K56Flex (the competing 56k protocol), and later the ratified V.90 standard didn't have this problem and you could achieve carrier speeds of 56,000 bps. This distinction was getting lost to time even back then with everyone just assuming it was some arbitrary FCC limit. This post from NANOG in 1998 explains it: https://archive.nanog.org/mailinglist/mailarchives/old_archive/1998-09/msg00011.html https://archive.nanog.org/mailinglist/mailarchives/old_archi...
- qingcharles 3y agoWhat's crazy is how badly I was waiting to upgrade from X2 to K56Flex just to get the 3kbps, which was like a life-altering speed difference back then!
- philistine 3y agoI’ll go to my grave thinking wow 3.2 kilobytes is a good connection!
- guidedlight 3y ago3.2kbps is the maximum rate of symbols (i.e. 3200 baud). So K56Flex squeezes one extra bit per symbol.
- rascul 3y agoI don't know how it worked but I never saw better than 53/54k with v.90 or v.92. Maybe there was more going on.
- dylan604 3y agoGrowing up, I lived in the boonies. Even with a 56k modem, the fastest it could go was 33.6k. I got to learn all of the info from the TFA when I was a trying to find out why. That’s also when I learned that some companies had full T1 lines all to themselves for a whopping ~1.5Mbps. Until some makes a call or sends a fax when your top speed drops 64k per phone line being used. It’s also why ISDN didn’t connect at 128k but at 112k since it just used two “bonded” lines of the T1
- reactordev 3y agoTwin bonded ISDN lines were my only option for anything faster than 33.6k. “You too could have had 128k for the low monthly price of $250 + cost of two phone lines + cost of equipment + labor”. When I finally moved to somewhere that had cable (and cable internet at 1.5mbps) I vowed never to return to the sticks. Then Elon came along… Starlink is probably one of the most useful inventions next to the lightbulb, DC current, Solar Cells, Toilets, desalination/ro and the WWW. I’ve gotten 100mb+ out in places where you have no cell service, no humans, no life, and no way of contacting anyone if in trouble. Starlink kept the connection no problem. I’m excited for the future if we can just get over our differences. XR, Starlink, EV’s, Highspeed rail, Electric planes, Mars…
- the_third_wave 3y ago[flagged]
- smolder 3y agoWhile we're making suggestions: don't bring up "derangement syndrome" if you want to be taken seriously. You ironically used it in a sentence appealing for less polarization. The comment was fine without.
- the_third_wave 3y agoRefusing to point out a problem does not make it disappear. I consider it clear as daylight that some people react irrationally to certain individuals whether those be Musk or Trump or anyone else. That phenomenon seems to be relatively new, e.g. in the times of Reagan there were many who clearly did not like the man but that never led to much more than "Ronald Raygun" and similar expressions and Bush - just as contentious - became "Shrub" but even then the reactions were not nearly as - to use a popular term - 'triggered' as they have become lately.
- jeffbee 3y agoSeems like the article failed to address the architectural reason why any of these details were relevant. A modem is a point-to-point communicating device and the signal has to be carried between two arbitrary points on the telephone network. DSL isn't really fundamentally different from a 56k, but the architecture is superior: DSL only goes to the other end of a wire, then the encapsulated IP traffic is forwarded elsewhere. 56k hit a wall because circuit switching has fundamental disadvantages. Packet switching allowed us to get past that.
- p3n1s 3y ago56k was not relevant for point to point communicating between arbitrary points on the network though. 56kbps dial-up worked in an asymmetric fashion with a fully digitally connected modem on one end (eg the ISP). Station to station analog modem standards capped out at 33.6k. > DSL isn't really fundamentally different from a 56k There's a great deal of additional integrated digital signal processing to make DSL work that was too costly for consumer modems at the time. I wouldn't agree with this assessment. And other than operating on phone lines for last mile it is completely different on all the layers and uses completely different equipment. > 56k hit a wall because circuit switching has fundamental disadvantages. Packet switching allowed us to get past that. There were circuit switched networks far faster than 56k, so not sure this had much to do with any inherent limitation. Packet switching has obvious advantages for network utilization and was a necessary evolution but I don't think it is relevant to any 56k limit or the revolution in DSP that make multi-megabit over copper pairs possible.
- jeffbee 3y agoAs you said, the DSP revolution was not scientific it was economic. They always knew how to do it, for decades, but it was unholy expensive. VLSI economically enabled DSL but it was a thing that they knew they wanted to do, and knew how to do, for decades. DSL technology was perfected before the 56K modem was even invented.
- p3n1s 3y ago> They always knew how to do it, for decades Unless we're limiting to the purely theoretical this is quite the hyperbole and in that case applies equally well to the 56k modem. Size and heat are also factors. The process nodes did not exist in the 70s and early 80s to produce the integrated circuits necessary. VLSI technically enabled DSL. The idea that somehow the difference between 1960s integration and 1990s is "purely economic" is pretty silly. If only they threw trillions of dollars more into research in the 60s would we have had the Intel Pentium then rather than 30 years later, maybe, but that is a useless line of reasoning. Someone has to actually do the "science". You need to actually design and produce a suitable line card equivalent for every subscriber that will support DSL speeds without taking up the space of an airport for it and the cooling. That didn't exist for decades before DSL was rolled out (which started barely a decade after it was patented). > DSL technology was perfected before the 56K modem was even invented. Considering that DSL standards continued to evolve after the 56K modem was obsolete this is also hyperbole. The other thing not yet mentioned which is pretty fundamental is that DSL eschews the 3.3khz bandwidth of POTS.
- Syzygies 3y agoI mentioned this article to my retired AT&T engineer wife, and she blurted out "Robbed-bit signaling!" https://en.wikipedia.org/wiki/Robbed-bit_signaling https://en.wikipedia.org/wiki/Robbed-bit_signaling
- hlandau 3y agoUnrelated, but I highly recommend anyone visiting Seattle check out the Connections Museum, open on Sundays only. It has several different genuine analogue and early digital telephone exchange frames saved from being scrapped from genuine telephone exchanges. They turn them on and you can actually call from one phone to another inside the museum. The museum itself actually shares a building with a real telephone exchange. Lots of old books, technical journals and schematics too. I just thought to post this since when I visited in September, some actual retired telecoms engineers were part of the tour group. One had been involved in the development of submarine cable technology.
- jonathankoren 3y agoI recently discovered their YouTube channel, and it is absolutely fascinating. https://youtube.com/@ConnectionsMuseum https://youtube.com/@ConnectionsMuseum
- Aloha 3y agoTechnically only the not yet functional DMS-10 is digital, everything else is analog. The 3ESS is a stored program, computer controlled analog switch - it uses the same remreed technology the 1AESS used to set up call links. Out of all of those however, panel is my favorite however, it sounds amazing to listen to, both the equipment and what the line sounds like. A call between a panel and the number 1 xbar sounds amazing, nothing quite sounds like revertive pulse signaling. Interestingly enough, there were three switches made that used RP internally - Panel, 7A Rotary and 1XBAR - and if you go find video of the 7A Rotary, you'll see it sounds almost exactly like panel, because the unique sounds of the rotary sequence switches both exchanges use.
- Solvency 3y agoIs the fact that the museum isn't available 85% or the week intentional irony or something?
- MBCook 3y agoThat was great. Never knew exactly where the 56k number came from. When 56k modems first came out I was able to get full speed, and it was a great upgrade. Then we moved and I could never pass 28.8 or so. Turns out in their infinite wisdom in the new development we moved to the phone company divided things up even more so they could get two lines out of what should have been one. 28 + 28 = 56. I don’t know if they were using some sort of compression or something so that it wasn’t audible on voice calls but it meant a modem was capped forever. The wait for cable internet was interminable (it came before DSL).
- bwann 3y agoUsually this meant the new neighborhood was put behind a subscriber loop carrier (SLC) which added an extra analog/digital conversion. Voice calls were getting digitized locally, sent across a T1 (only 4 wires needed, instead of 96-192), and back to analog to the normal frame at the CO. The effect of this was the telltale sign of carrier speeds only hitting 26,400 bps.
- MBCook 3y agoThat’s basically the kind of thing I suspected. Thanks! I wonder if that config screwed them when it came time to try to sell DSL. It still wasn’t available years later when I moved out.
- redm 3y agoThis brings back a lot of memories, but I think what I lament the most is that this was really the end of American soup-to-nuts engineering in telecom. At the end of the 56k production and the start of G.Lite DSL, all this engineering started going to China to save money. Long gone are the days of Radio Shack and companies EE's designing, prototyping, testing, and manufacturing electronics. Sad.
- rasz 3y agoUsenet was a fantastic period correct source of information. Here an archive of insightful posts about phone networks https://yarchive.net/phone/ https://yarchive.net/phone/
- flyinghamster 3y agoA great source of archived information - and TELECOM Digest is still functioning. http://telecom-digest.org/ http://telecom-digest.org/ http://www.telecom-digest.org/latest-issue.html http://www.telecom-digest.org/latest-issue.html
- pjmlp 3y agoNo mention of dual speed models like Diamond, which would use two 56k lines simultaneously?
- ryan-c 3y agoThat could even be done with two completely separate modems.
- pjmlp 3y agoNot really, as with using something like the diamond that was hidden by the driver.
- don-code 3y agoIndeed, PPP has a multilink feature which an bond packets from multiple modems into a single bitstream. Both the client (your machine - Windows 98 could do it) and your ISP needed to support it. I remember trying this a few times while at my parents' store. My dad would tell me which phone line I could use that day - either the dedicated line used to process credit cards (if they were closed), or a spare line off the PBX. But occasionally, I was allowed the use of both - and luckily had a pair of PCMCIA modems with the dongles in different places - and could get speeds well above 56k.
- NikkiA 3y agoDiamond called theirs 'shotgun technology' iirc. I used a pair of USR external modems cobbled into a shotgun configuration via a linux proxy to manage our internet connection, but we got DSL shortly after (and surprisingly early for the rural location we were in).
- deleted 3y ago[deleted]
- marcus0x62 3y agoThis article glances at, then misses the fundamental technical reason why modems topped out at ~ 56kbps: that’s really all the bandwidth that is available on a POTS line, due to the bandpass filter, the ADC on the other end, companding, and engineering practices that led the Bells to maintain their lines to the standards of an analog voice conversation. The robbed-bit signaling thing is really a red herring: it was a problem, but not THE problem. At the time analog 56kbps modems were popular, it was already possible to negotiate 64kbps/8-bit clean DS0 channels over T1 — you just needed a PRI or an inter-machine trunk to do so. In fact, if you were an ISP at the time, you generally needed those modems connected to T1 PRIs or IMTs anyway to support your ISDN customers economically. (My memory may be getting fuzzy on this, but I also remember that certain access concentrators with k56/v.90 digital modems would only negotiate the higher analog speeds on a PRI or IMT bearer channel.) What there was absolutely no appetite to do, on the part of the voice carriers, was beef up the bandwidth available on POTS lines by developing new ADCs, getting rid of companding, or engaging in labor-intensive “facilities grooming”[0] for a POTS subscriber, in the way they routinely did for T1[1] circuits. 0 - Telcos call their lines and equipment “facilities.” Grooming, in the context of outside plant (telco terminology for the physical cabling that goes to subscribers) means to select wire pairs that exhibit good noise and echo characteristics and to remove elements, like poor splices and bridge taps, that impede performance. 1 - T1s, unless delivered to a customer via an optical transport network, use the same copper lines as analog POTS lines. Originally, T1s required two pairs (four wires). This eventually was replaced with HDSL4 (two pairs, but better distance and repeater characteristics,) then HDSL2 (single pair.) As the names suggest, the encoding used was a DSL variant.
- Sesse__ 3y agoAnd even for 56kbps, you need to have the ISP end talk digitally to the telco, so that you don't get the noise (including from the DAC) of the local loop on the ISP end. That's really what pushes the SNR far enough down to make it work (and why the uplink is only 33.6kbps; I guess they didn't want to try to make a separate modulation for that direction).
- marcus0x62 3y ago
- deleted 3y ago[deleted]
- kazinator 3y agoHere is a much shorter explanation. PSTN voice calls go over 64 kbps digital links (e.g. G.711 uLaw codec, 8 kHz sample rate). 56 kbps pushes close to the theoretically available channel bandwidth. That's all there is to it: information coding theory. To get more than around 56 kbps from modems, you would need more fidelity from the underlying lines: a wider-band, lower noise pure copper end-to-end connection, or higher bitrate codecs.
- xcv123 3y agoShorter but missing an important detail. The article explains that every 8th bit is lost to allow for control signalling that steals the 8th LSB on every 6th frame. Hence 7/8 * 64 = 56. https://en.wikipedia.org/wiki/Robbed-bit_signaling https://en.wikipedia.org/wiki/Robbed-bit_signaling
- chriscjcj 3y agoI was never able to exceed 24kb/s with my "56k" modem. I came to find out that the phone company (in Austin TX) was using a single pair to service more than one customer in my apartment complex. Naturally, whatever piece of equipment they used to accomplish this stymied faster modem speeds. I finally installed an ISDN. That was delightful. Not only did it allow me to have two lines - one for voice and one for data - the netgear RT-338 ISDN router automatically dialed my ISP instantaneously. It felt like I was always connected because I didn't have to wait for a modem handshake. Speeds were more than twice as fast as what I could get with my analog modem. However, by far the MOST IMPORTANT thing (and mostly the reason I installed the ISDN in the first place) is that my latency took a nosedive allowing me to become an LPB with a 50ms ping time on QuakeWorld. >:-D (Shoutout to Charlie S. from OuterNet, Austin's best ISP in the 90's)
- zzzcsgo 3y ago[dead]
- queuebert 3y agoWhat is an LPB?
- zain 3y agoLow Ping Bastard
- hypercube33 3y agoBack in the day LPB was someone with low pings (remember dial up was 150 to 300ms sometimes) and they'd have an upper hand on games before they were "unlagged" with prediction code.
- oh_sigh 3y agoA common lament among the dead 15 years ago in real time online gaming...low ping bastard/bitch, basically just saying the only reason you got the kill is because your ping is 60ms and mine is 250ms.
- fanf2 3y agoMy understanding from discussions about modems in the mid 1990s was that the bandwidth limit for POTS-to-POTS modems was about 36kbit/s, because the signal has to go DAC (modem) -> ADC (telco) -> DAC (telco) -> ADC (modem), and the modems at either end are not synchronized with the telco’s digital path. The thing that allowed speeds to increase to 56kbit/s was digital connections at the ISP end: typically the ISP would get a T1 or E1 circuit fed into a box that would act as 24 modems, but purely digital and synchronized with the telco. So the signal now went Ascend MAX (isp) -> T1 (telco) -> DAC (telco) -> ADC (modem), providing much less quantization noise.
- rollcat 3y agoI loved the article, and when I love an article the first thing I do is look for the website's news feed. From <https://www.10stripe.com/10blog/ https://www.10stripe.com/10blog/>: > The blog has been discontinued due to Wordpress security concerns. Keep this tragedy in mind next time you pick your tech stack.
- toomuchtodo 3y agohttps://web.archive.org/web/20111202070238/https://www.10stripe.com/10blog/ https://web.archive.org/web/20111202070238/https://www.10str...
- theoldlove 3y agoBoils down to the fact that a phone line to a house was built with a a certain amount of bandwidth for a human voice, implemented with a lowpass filter of 4 kHz. But the article doesn’t explain or show why the magic 4 kHz number was chosen.
- rasz 3y agoThere are no filters and cable is not BW limited, otherwise ADSL wouldnt work on same wiring.
- quercusa 3y agoSee the section Long, long ago
- theoldlove 3y ago“Ultimately, they settled on approximately 3.2 kHz.” doesn’t really explain who made this decision, when, or why. All we get is “Long ago, when the phone networks were still completely analog, when the first real phone networks were being built, the engineers that were designing them faced a decision.” Who were those engineers? What company? How did they test what would be adequate bandwidth?
- Arubis 3y agoOhhhh, is _this_ where the 7-bit transfer settings came from? That always seemed a weird number to me (unless a bit was instead repurposed as a parity bit).
- aYsY4dDQ2NrcNzA 3y agohttps://en.wikipedia.org/wiki/SupraFAXModem_14400 https://en.wikipedia.org/wiki/SupraFAXModem_14400
- RecycledEle 3y agoTL/DR The standard for digital phone lines is (was) 7 bit samples multiplied at 8,000 samples per second. 7 * 8000 = 56,000 = 56k
- Lammy 3y ago> Why 24 of them in each DS-1? No idea. Legacy of https://en.wikipedia.org/wiki/12-channel_carrier_system https://en.wikipedia.org/wiki/12-channel_carrier_system
- DrNosferatu 3y agoHad ISDN in Europe at home in the late 90s. How common was it in the US and elsewhere?
- rasz 3y agoSo you are from Germany? :) nobody else invested in ISDN. Whats more US ISDN was incompatible and incumbent telcos fought hard against implementing anything allowing users faster speeds without bigger bills https://yarchive.net/phone/isdn_politics.html https://yarchive.net/phone/isdn_politics.html
- DrNosferatu 3y agoNope: Portugal B-) Back in the day, our incumbent telco was quite cutting edge technologically.
- chidi0202 3y ago[dead]