Abstract: A portable communication unit (120) capable to communicating on a plurality of communication channels. The portable communication unit (120) includes a method for selecting one of an at least two fixed communication units (102) for communicating therewith.

Abstract: A communication system (100) comprises a central controller (102), a plurality of base stations (104 and 106) coupled indirectly via the central controller and using radio frequency waves to communicate to communication unit(s), one of the base stations being a source base station (104) and at least another base station being a destination base station (106), and at least one communication unit (108) operable on the base stations. The communication system is able to synchronize a handoff of the communication unit between the source base station to the destination base station, wherein the source base station is the originating communication resource for the communication unit and the destination base station is the recipient communication resource for the communication unit subsequent to the handoff.

Abstract: A wireless communication system includes a portable communication unit (PCU) (120) and a plurality of fixed communication units (FCUs) (102) covering a plurality of radio coverage areas (108, 110, 112). The FCUs are coupled to a telephone system (114) by telephone lines (116) shared in common by the FCUs (102). The PCU (120) is associated with one of the telephone lines (116) for receiving an incoming call. THE FCUs (102) are coupled to the telephone line (116) in response to an incoming call, and signals are transmitted from the FCUs (102) to establish a wireless link with the called PCU (120). When one of the FCUs (102) receives a response from the called PCU (120), the receiving FCU (102) establishes the wireless link and the rest of the FCUs (102) stop further signal transmissions.

Abstract: In frequency-hopping spread-spectrum systems, it is necessary to maintain frequency and bit synchronization (sync) between the transmitter and receiver in order to maintain quality data recovery at the receiver. A protocol is described which includes a synthesizer lock field (109) to allow frequency sync, a clock sync field (123) to achieve quick clock sync, and a data sync field (125) to provide data sync. Other fields are provided in the protocol to allow both voice (141) and data (127) transmissions, inband signalling (139), and error correction (143). A method and apparatus, driven by a microprocessor (303) and ASIC (301) combination, are described that generate and transmit this protocol.

Abstract: A conference call feature is offered for use with spread spectrum cordless communication systems. The conference call feature is achieved through the alternate use of redundant communication resources by units on the conference call. The redundant communication resources in spread spectrum communication systems transmit duplicate copies of messages in high noise environments. In residential environments, noise tends to be less of a problem and can, hence, be used to support a conference call feature.

Abstract: External interface control circuitry is described that couples a microcomputer system (100) to an external device (800). The control circuitry includes a microcomputer (102), a power switch (108) for applying power to the external device (800) in response to a PSC* signal, bus control (104) for gating interface signals from the microcomputer (102) with a PD* signal for application to the external device (800) and a peripheral interface adapter (106) for producing the PC and PD* signals and coupling the PI* and READY*/IRQ* signals to the microcomputer (102). A power-up sequence is executed by the microcomputer (102) in response to grounding the PI* signal when the external device (800) is plugged into the microcomputer system (100). Next, the external device (800) produces a binary zero state of the READY*/IRQ* signal, and in response microcomputer (102) produces a binary one state of the PD* signal and thereafter the PC signal.