When jet test pilots first sought to break the sound barrier, they did so without knowing exactly what was on the other side. Some believed the goal was impossible, that mankind had reached its speed limit. The more superstitious pilots believed that dragons waited at 760 miles per hour (Mach 1) to gobble up the men and their little flying machines. And yet, the pilots all continued to push the speed limits until the barrier broke - and then they tried to fly even faster.
Today, modem manufacturers are emulating those test pilots of legend, pushing against the speed limits imposed by analog telephone line connections. Presented with a new class of modems capable of achieving speeds approaching 56,000 bits per second (56 Kbps), it's tempting to ditch our pokey old 28.8 Kbps and 33.6 Kbps paperweights and buy the faster models. In this case, however, there really are dragons waiting on the other side - for now, anyway.
[Note that I'm going to use the term "speed" here even though it's not accurate. Modem "speeds" are actually "throughputs" because speed is a measure of distance per time, whereas throughput is a measure of moving some unit (bits, in this case) per time.]
The Good News -- Most of the marketing material currently being pushed by modem manufacturers is accurate - at face value. Speeds of 56 Kbps are possible over existing telephone lines without the addition of extra hardware other than a new modem supporting 56K technology. In fact, some of the current 33.6 Kbps modems on the market today can even be upgraded to the 56K speed by a process known as a "flash upgrade": you transfer new firmware - the modem's internal operating instructions that control how it works - from your computer to your modem's permanent memory chip (sometimes referred to as EEPROM - Electrically Erasable Programmable Read-Only Memory).
Although your computer may claim a 28.8 or 33.6 Kbps modem connects at speeds of 57.6 Kbps or 115.2 Kbps, these speeds are just how fast the port between your computer and the modem is running, rather than how fast the connection between your modem and a remote modem is running. On the other hand, 56K modems are actually capable of sending information at the higher speed. This is due both to new modem technology and to the digital connections that link most Internet service providers' (ISPs) offices to the switching stations at local phone companies where calls are routed.
Flying Faster -- Here's how the data transfer works. An ISP's server relays a packet of information from the Internet over the ISP's internal network to the modem that you're connected to via a phone line. Up until that final stage, the information is digital; when it hits the modem on the ISP side, it's converted from digital signals (used by the ISP's systems) to analog frequencies (the noise you hear if you pick up the line while you're connected to the Internet).
The information, now in analog form, goes from the ISP's modem to the switch at the phone company's central office (or CO) to which the ISP's phone lines are connected. (There can be several or even dozens of CO's in a major city.) When the data hits the switch, it is converted from analog back to digital for its journey through the telephone company's network (officially known as the public switched telephone network, or PSTN), ending up at the switch connecting to your phone line. The data undergoes another digital-to-analog conversion to travel to your modem, which then takes the analog signals and converts them once again into digital signals that your computer receives. The numerous digital-to-analog conversions result in a significant amount of "noise," slowing the network speed to 35 Kbps (a figure reached by a mathematical formula known as Shannon's Law).
With 56K technology, the digital-to-analog conversions that aren't necessary are taken out of the picture. ISPs can connect themselves to the PSTN digitally, so information only needs to undergo a digital-to-analog conversion when it leaves the PSTN en route to your modem. This streamlining of the process reduces noise and increases capacity of the connection, since the signal stays digital from ISP to PSTN.
If you'd like to blow a few million neurons trying to understand the technology behind regular modems (and the Rockwell version of 56K), you can read a white paper at Rockwell's site.
The Dragons -- So, you might ask, why don't we all have 56K modems on our desks right now? Unfortunately, there are several barriers blocking the wide-scale implementation of 56K technology.
One of the key problems is standardization. As yet, there is no generally accepted standard for 56K communications, and a ruling by the International Telecommunications Union (ITU) isn't expected until at least September 1998. In the meantime, several modem developers, including 3Com (recent purchaser of U.S. Robotics), Lucent Technologies, and Rockwell International, have emerged with functional, but incompatible, technologies in the hope of forcing standards by way of public and industry acceptance. Until one set of standards prevails, users buying either technology run the risk of ending up with the modem equivalent of the varying gauges of railroad tracks through history.
Another problem concerns ISPs. Already burdened with having to support multiple modem technologies, ISPs will need to invest heavily in upgrading their systems to support 56K devices. To make matters worse, they won't be able to just buy a rack of 56K modems and put them on the network. Instead, they must install "central site" modems that are digitally connected to the PSTN. (This also means that if two users buy 56K modems, they usually won't be able to create a direct connection between them at top speed.)
Even if a standard is reached, and ISPs invest in central site modems to serve their 56K customers, another problem remains: those users will only be able to connect at a top speed of 53 Kbps. Pushing a full 56 Kbps through existing telephone wires requires a higher voltage than the United States Federal Communications Commission (FCC) allows. Until the FCC increases the voltage limit, or grants waivers for 56K communications, adopters of the new technology will be limited to the slower 53 Kbps speed, which is itself not always achievable. Tests done by computer magazines show a 40 to 50 Kbps range is more typical.
And, of course, there are lawsuits. In 1995, a Stanford University associate professor named Brent Townshend presented Rockwell Semiconductor with his ideas for a technology which would enable 56 Kbps transmissions. Allegedly, Rockwell assured him that they would obtain his permission if they were to use or disclose his ideas. Rockwell then developed their K56Flex chipset independently, so Townshend filed suit in October 1997 asking for compensation and an injunction against future use of K56Flex.
While courts debate over who created the technology, they will also be looking at whether or not modem manufacturers have deceived consumers by inflating claims about the current 56K modems. In May 1997, a California lawyer filed a consumer-action lawsuit against several companies on the grounds that their advertising is promising speeds and features that the existing hardware cannot deliver. He is seeking injunctions on the alleged false advertising, and unspecified compensation for people who have bought 56K modems.
Oh, and did I mention that the 56K speeds only apply to downloading information from ISPs, not uploading it? The ISP's central site modem can take advantage of network synchronization and a few more obscure features that allow it transmit at up to 53 Kbps; the user-to-ISP direction can't take advantage of those extra cues and is limited to the maximum analog speed of 33.6 Kbps.
Applying the Brakes -- Does this mean we're all relegated to 28.8 Kbps and 33.6 Kbps speeds? Does this mean that to cruise the Internet quickly, will you need to invest money and time in technologies like ISDN, frame-relay, ADSL, cable modems, or fractional T1 lines?
Nope. If you desperately need higher speeds now, by all means explore those other options. If you've been using the Internet with a 14.4 Kbps or 28.8 Kbps modem and are already looking to upgrade, spending a couple of hundred dollars on a 56K modem will probably pay off and allow you to work at 33.6 Kbps. Many manufacturers are guaranteeing that their products will allow a flash upgrade (generally at no cost) to whatever the final 56K standard turns out to be - even if it's a combination of the two current technologies. In the meantime, be sure to call the friendly folks at your ISP and ask them which direction they've taken. (Some ISPs have banks of both modems to avoid alienating their most eager customers.)
If it's not killing you to hold steady at 28.8 Kbps or 33.6 Kbps (the speed at which I currently connect), you'll probably want to sit back and wait for the dust to settle. Given the current demand for faster Internet access, it's inevitable that the 56K barrier will eventually evaporate, leaving us to look ahead to speedier connections.
[Jeff Carlson is the managing editor of NetBITS and TidBITS. This article is adapted and updated from "Speed Jockeys on the Internet," which originally appeared under his byline in the 15-Mar-97 issue of adobe.mag. Adapted with permission from Adobe Systems, Inc.]