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Radio Frequency Modems

A modem (modulator/demodulator) is a device that transforms signals from one form to another. Modems are usually used over phone lines, but an RF (radio frequency) modem converts radio signals to other forms.

In August 1991, CUE, a paging company, announced the CUE LapCom RF modem. This modem lets senders transmit data without knowing where the intended recipient is, and it lets intended recipients accept data without dialing a special number. The sender dials an 800 number and uploads the data with the intended recipient's ID. CUE's computer uplinks the data to a satellite and the satellite downlinks it to 270 FM radio stations in its footprint. The radio stations then broadcast the data on their FM subcarriers.

A few seconds after the sender transmitted the data, the intended recipient's LapCom picks up the FM signal and receives the data. This system reaches over 90 percent of the U.S. and Canadian population. CUE currently supports 70,000 subscribers and is planning to offer the LapCom service at $60 to $75 per month. CUE is pricing the LapCom itself to be competitive with normal modems.

Gregory J. E. Rawlins