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Paging Networks

Pagers generally operate over 25 kHz channels in the 900 MHz band. In 1984 the FCC dedicated 1 MHz of 40 channels in this band for nationwide paging purposes. Paging services are provided by RCCs (Radio Common Carriers) and PPOs (Private Paging Operators). RCCs are regulated by the FCC and the state PUCs, and make use of FCC-designated frequencies. PPOs are unregulated, but must share spectrum with other users in the VHF and UHF bands.

SkyPage and other paging network providers provide a VSAT satellite link to terrestrial paging networks, as shown in Figure 12.6. In this fashion, the local paging systems are networked in order that a page can be delivered across a wide area rather than only locally. Networking is also accomplished through leased lines and X.25 packet-switching.


Figure 12.6  Terrestrial paging network with satellite interconnectivity.

Paging Equipment

Pagers can be classified as tone-only, numeric, and alphanumeric. Tone-only pagers cause the device to emit an audible tone. Numeric pagers allow the receipt of numbers, only, on a display, whereas alphanumeric pagers allow the receipt of both alpha and numeric characters.

Two-way paging systems have been available abroad for years, but only recently have they been introduced in the United States by Destineer, MobileComm, PageNet, and others. Such pagers are alphanumeric, supporting the display of a message and return number (e.g., telephoner, pager). Additionally, the user can select and transmit a return message from a small set of predetermined messages. The return messages are also user-definable through an RS-232 serial link between the pager and a PC. The messages can be up to 50 characters in length [12-12] and [12-13]. Pagers have also been incorporated into other devices, such as watches (e.g., Seiko and Swatch) and cellular telephones. The Seiko pager/watches use the FM radio band, rather than standard pager frequencies.

Whether standalone or merged into another device, typical capabilities include some combination of alphanumeric display ([le]32 Characters), two-way communications, message storage ([le]231 messages), audible, and vibration alert, and fax receipt (in development). Additionally, several manufacturers offer PC Pager cards which fit into the PCMCIA (Personal Computer Memory Card Industry Association) slot of laptop PCs. They can also operate independently. All such cards are PCMCIA type II and do not require external power supplies. This approach effectively merges the wireless applications of two-way alphanumeric paging, computing, and email. The ability to receive an alphanumeric page through a wireless, laptop PC and to then respond with an email message is truly extraordinary. Although these developments are recent and not widely available, they clearly will achieve some significant level of acceptance in future as the workforce becomes increasingly mobile. Manufacturers of such PC Paging cards include HP StarLink, Motorola, Sony Electronics, and Toshiba.

Paging Applications

At the extreme, pagers currently support applications including message notification, information services, stock quotes, event information (1996 Olympics), and email.

Paging Developments

Motorola recently has floated a new set of proprietary solutions, which it hopes to see officially accepted as industry standards. Those solutions provide two-way messaging, support data transmission, and provide greater bandwidth, and include include FLEX (2,400 bps, 25 kHz), ReFLEX25 (6,400 bps, 25 kHz), ReFLEX50 (25.6 Kbps, 50 kHz), and InFLEXion (112 Kbps, 50 kHz; 240 Kbps, 100 kHz; supports voice).

International Paging

Paging in Europe is somewhat constrained by the lack of agreement on common standards, although the POCSAG standard is generally recognized, supporting transmission of 1200 bps and operating in the 150 to 170 MHz band. A pan-European digital paging system known as ERMES (European Radio Message System), supported by ETSI and the EC, is making progress. ERMES operates at 6,250 bps in the 170 MHz band and uses FSK as a modulation method.


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