56K modems are analog modems capable of speeds near 56 kbit/s when connecting to a service that has a digital connection to the phone network. 56 kbit/s (56 kilobits per second) is the data rate of a normal single channel digital telephone line in North America. ...
It is important to note that this technique cannot be used between two 56K modems and that when two 56K modems connect they will revert to slower standard analog methods.
At the end of 1997 there were two rival modem designs using this technique: k56flex and US Robotics' X2. In February 1998 the ITU proposed a 56 kbit/s standard called V.90, which was formally approved during September1998. 1997 is a common year starting on Wednesday of the Gregorian calendar, and was designated the International Year of the Reef. ... A modem (a portmanteau word constructed from modulator and demodulator) is a device that modulates an analog carrier signal (sound), to encode digital information, and that also demodulates such a carrier signal to decode the transmitted information. ... K56flex (originally called the K56Plus) was a modem chipset from Rockwell and Lucent that gave users the possibility of receiving data on ordinary phone lines at 56 kbit/s as opposed to the previous maximum of 33. ... U.S. Robotics (popularly nicknamed USR), based in Schaumburg, Illinois and founded in 1976, is a company that makes computer modems and related technologies. ... US Roboticss 56K modem protocol for upload under V.34+ at 33. ... The International Telecommunication Union (ITU) is an international organization established to standardize and regulate international radio and telecommunications. ... V.90 is an ITU-T recommendation for a modem, allowing 56 kbit/s download and 36 kbit/s upload. ... September is the ninth month of the year in the Gregorian Calendar and one of four Gregorian months with the length of 30 days. ... 1998 is a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean. ...
References
This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.
56Kmodems were designed to take advantage of the digital portions of the phone network and of the fact that while analog-to-digital conversions are affected by quantization noise, digital-to-analog conversions are not.
Although the phone network is increasingly digital, the portion of the network which connects homes to the CO is the slowest portion of the network to convert to digital and will probably remain analog for quite awhile.
The frustrating thing about 56K connectivity is the fact that so much of what can impact the ability to achieve it are factors that an individual has no control over.
Ideally, a 56kmodem operating under any protocol should be able to attempt to connect at the highest possible speeds, negotiating down to slower speeds as much as is necessary to achieve a stable connection.
In actuality many 56kmodems are not good at reverting to slower protocols; they insist upon trying to transfer data with their higher rates, even if they have to do it slowly.
If you use a 56kmodem and do not seem to be able to achieve speeds above 33.6 kbps, then the modem is probably not able to achieve higher speeds for one or more of the reasons discussed earlier and is falling back to the slower, more stable v.34 standard.
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