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Nathan J. Muller
Not too long ago, the general consensus was that modems would be supplanted by ISDN terminal adapters connected to digital lines. Now, not only is modem use growing, but new technologies such as sound boards, message centers, and fax capabilities have revitalized this market segment.
Traditionally, modems have been used for transferring files, accessing bulletin boards, and connecting users to the Internet. Today, there are multifunction modems that include sound boards, message centers, and fax capabilities. There are also modems that work over wireless and cable television (CATV) networks, and modems that are capable of supporting a voice conversation and data transfer simultaneously over the same line. Very soon there will be modems that double the current speed of 28.8K bps to 56K bps, facilitating multimedia communication.
Even with all these innovations, modems still perform the same basic functions modulation and demodulation. They convert (i.e., modulate) the digital signals generated by standalone or networked PCs into analog signals suitable for transmission over dialup telephone lines or voice-grade leased lines. Another modem, located at the receiving end of the transmission, converts (i.e., demodulates) the analog signals back into their original digital form.
For years, modems have been available in external, rackmount, or internal versions. But even in packaging, there is plenty of room for innovation.
External modems are standalone hardware devices that connect to a microcomputers communications port via telephone cabling. They are equipped with front-panel status indicators that inform users of modem activities. Rackmount modems are full- or half-cards that reside in an equipment frame. From there, the individual modems connect to the various PCs. External modems typically reside on an office desk, while the rackmount versions are located in a convenient equipment cabinet or wiring closet for easy troubleshooting and maintenance.
Internal modems, which insert into an available expansion slot inside the computer, are best suited for users who rely extensively on the wide area networkwide area network (WAN) to do their jobs. For users who require only occasional access to the WAN, companies can save money by equipping a communications server with a pool of modems that can be shared by many users on a first-come, first-served basis.
Another type of internal modem is the size of a credit card and standardized by the Personal Computer Memory Card International Association (PCMCIA). Both wireline and wireless modems are available as plug-in cards to the PCMCIA Type II slots in portable computers. There are even multifunction PCMCIA cards that combine the modem and LAN adapter (Ethernet or Token Ring) on the same card, giving users more connectivity options without requiring an additional card and using up the second PCMCIA slot included with most laptop and notebook computers.
There are also PCMCIA cards that connect to various wireless messaging services. They have a built-in antenna and can even act as standalone receivers when the computer is turned off. Some cards are programmable, allowing users to access or receive messages from different wireless services, including those based on cellular digital packet data (CDPD) cellular digital packet data and packet radio services such as ARDIS and RAM Mobile Data. Some wireless modems can automatically identify the type of modem protocol used at the receiving end and adjust their own operation and speed accordingly.
Like wireline modems, wireless modems are packed with functionality. There are CDPD modems, for example, that work with any DOS- or Windows-based computer, supporting V.22bis, V.23, V.23bis, V.42bis, Group 3 fax and V.17 wireline fax and data protocols, plus Microcoms MNP-10 cellular protocol or Paradynes Enhanced Cellular Throughput (ECT) protocol.
Another new way vendors are packaging modems is by integrating them with integrated services digital network (ISDN) terminal adapters. This allows users to communicate with conventional dialup services at up to 28.8K bps and also take advantage of ISDN when possible all without cluttering the desktop or having to use up scarce slots in the PC.
Multiport modems of this kind are being introduced for the corporate environment. U.S. Robotics, for example, offers two models that dynamically support both digital and analog connections. Aimed at telecommunications managers who use a lot of perfectly good analog lines on their networks, the companys 8-port MP/8 I-Modem and 16-port MP/16 I-Modem can handle analog and ISDN calls, making them suitable for companies that are rolling out ISDN connections to analog users. The modems actually determine whether they are connected to an analog or digital line and operate in that mode automatically. The MP modems act as a front end to existing terminal servers. With a channel-aggregation feature, users can add up to 64K bps of bandwidth over each ISDN link during Internet access or other tasks that call for additional bandwidth.
The next step in modem packaging is to eliminate the need for dedicated hardware altogether. Intel is trying to do precisely this with its native signal processing (NSP) initiative that embeds software emulation of modem and sound card hardware in the Pentium chip. Known as MMX technology, the idea is to allow any Windows application to have access to features implemented in a special driver to send and receive E-mail and faxes or to play sound files with no modem or specialized hardware, aside from the main CPU. In effect, NSP will give every Pentium PC the ability to manage basic communications and multimedia tasks, which in turn will let software developers add these features to their applications without having to worry about whether customers have the necessary hardware.
Intels MMX technology is what makes native signal processing on the Pentium platform feasible. A 100-MHz Pentium would have to dedicate 60% of its resources to V.34 modem processing. With MMX, a 200-MHz Pentium would need to use only 20% of its resources, which is insignificant to most users.
Motorola is about to enter the emerging market for host signal processor (HSP) modems, which rely heavily on software and the processing power of the host PC. Rather than relying on its own digital signal processor (DSP), this type of modem is based on a less-expensive application-specific integrated circuit (ASIC) and takes advantage of a PCs central Pentium chip for processing power. Motorola plans to introduce an HSP product line geared toward remote access, telecommuters, and mobile workers. The product line will eventually go beyond analog modems to include ISDN terminal adapters and digital subscriber line modems. HSP technology has been around for several years, but has only recently become feasible because of the growing availability of faster desktop computers based on the Pentium chip.
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