Motorola Corporation

Mark Nadir

William J Kuznicki

Gordon Wayne James

John D Hauck

Jerome A Nieds

An alerting device, such as a radio pager, which produces an audible alerting signal, in response to a unique identifier received and decoded by said device, incorporates circuitry for periodically reminding the user that a lagging signal has been received. In this context, a short alerting signal or call reminder alert occurs periodically upon cessation of the originating alert and/or message. This method of operation continues until the user manually discontinues it.

Call reminder for a radio paging device

A switched capacitor filter system is provided which is programmed to filter a predetermined sequence of tone signals. The filter system is de-rung after each selected tone signal is detected by increasing the clock frequency of the switched capacitor from the programmed value corresponding to a tone signal up to a center frequency substantially greater than that of the tone signals. Energy stored in the filter system is thus quickly dissipated. Rapid sequences of sequential tone signals are thus filtered without the problems associated with ringing of the filter.

Method and apparatus for de-ringing a switched capacitor filter

A system for radio-telephone communication between a user at a remote location and the commercial telephone system or between two users at remote locations comprises a fixed terminal that is connected by wire lines or the like to the commercial telephone system and a plurality of portable radio units. The terminal is equipped for duplex operation on a plurality of channels, each of which uses separate frequency bands for transmitting and receiving. Each of the portable units is a simplex transceiver adapted to receive on each of the frequencies of transmission from the terminal and to broadcast on each of the frequencies received by the terminal. The terminal places a channel acquisition tone on an unused channel that is the next to be used. The terminal calls portable unit by shifting channel acquisition tone to another channel and broadcasting an identifier to the portable unit. The called portable unit responds to its individual identifier by sounding an audible alert and producing an audible verbal message if one is sent from the terminal. A portable can also originate a message by calling the terminal. A delay period provides time for the portable to recognize its identifier before beginning to scan for channel acquisition tone. Circuits and logic in the portable produce a busy signal if the user attempts to call at a time when the portable is not receiving channel acquisition tone. A reset in the portable unit provides means for the user to terminate the call.

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Ft. Lauderdale, FL, United States of America

Mark Nadir