Coaxial cable has a very large bandwidth, but signal attenuation becomes a major problem at high data rates if a baseband digital signal is used. QAM used a combination of phase shift and amplitude to encode four bits per symbol. The drawback of this approach is a loss in quality, which causes image content to become pixelated and smeared. Overall throughput is 7. Archived from the original on 2 October

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With a 44K connection the Accura downloaded the 7.

For the most part, cable installations use the same kind of wiring found in coaxial ethernet networks. ISPs employing this approach often advertise it as “accelerated dial-up”. You really want a ADSL promises most of the speed of cable modems over regular telephone lines.

If you are hosting a website, this can be a strong argument against adding a 56k modem. The idea was to transmit analog audio signals that would translate directly into specific PCM pulse-codes that the phone system could send all the way to the receiving modems at the Internet Service Provider’s ISP’s point of presence POP. The first test I put k56rlex Accura modem through was a Smartupdate from Netscape.

If you wanted to use a 56k modem for remote access, read point 6 again.

Hayes Accura V.90/K56Flex Internal and External Data/Fax Modems

Still, speed should be better than alternative technologies. Still, to send bits of data via modem will take at least ms latency plus input plus transmission. During the call initiation, the modem would transmit a series of signals and wait for the remote modem to respond.


Log in Don’t have an account? Wikibooks has a book on the topic of: The dial-up modem is still widely used by customers in rural areas, where DSL, cable, satellite, or fiber optic service is not available, or they are unwilling to pay what these companies charge.

Archived from the original PDF on By the k56dlex modems came around, The bit rate increases were achieved by defining four or eight distinct symbols, which allowed the encoding of two or three bits per symbol instead of only 1.

Hayes Accura V/K56Flex Internal and External Data/Fax Modems

All drivers were removed and I tried again. Software running on the host computer can convert any image into fax format, which can then be sent using the modem. The same applies to V. If your modem compresses data at 2: The difference between a cellular router and a wireless modem is that a cellular router normally allows multiple people to connect to it since it can route data or support multi-point to multi-point connectionswhile a modem is designed for one connection.

This was often difficult to acheive. Many other standards were also introduced for special purposes, commonly using a high-speed channel for receiving, and a lower-speed channel for sending.


Modems grew out of the need to connect teleprinters over ordinary phone lines instead of the more expensive leased lines which had previously been used for current loop —based teleprinters and automated telegraphs. Newer types of broadband modems are also available, including satellite modems and power line modems.

Wireless modems are often referred to as transparent or smart. Archived from the original on 20 September The Hush-a-Phone decision applied only to mechanical connections, but the Carterfone decision ofled to the FCC [ who? Both technologies reached the market around February ; although problems with K56Flex modems were noted in product reviews through July, within six months they worked equally well with variations dependent on local connection characteristics.

Not all phone lines will support 56k modems. The server-side compression operates much more efficiently than the on-the-fly compression done by modems because these compression techniques are application-specific JPEG, text, EXE, etc. Smart modems come with media access controllers inside, which prevents random data from colliding and resends data that is not k56flx received. Archived from the original on 30 November