Abstract: In general, a mobile unit for communicating with other mobile units assigned to a group within a Multipoint Voice Network (“MVN”) having a plurality of groups is shown. The mobile unit may include a time division multiple access (“TDMA”) transmitter, a TDMA receiver, and a controller. The TDMA transmitter is enabled to transmit a set of multiple carrier frequencies, where the TDMA transmitter is configured to transmit on one frequency chosen from a sub-set of multiple carrier frequencies from the set of multiple carrier frequencies. The sub-set of multiple carrier frequencies corresponds to the group to which the mobile unit is assigned. The TDMA receiver is configured to receive and demodulate the sub-set of multiple carrier frequencies and the controller configures the TDMA receiver to receive and demodulate the sub-set of multiple carrier frequencies that is assigned to the group. A switch may be utilized to set time slots for the TDMA transmitter and the TDMA receiver.

Abstract: In general, a mobile unit for communicating with other mobile units assigned to a group within a Multipoint Voice Network (“MVN”) having a plurality of groups is shown. The mobile unit may include transmitter, receiver, and controller. The transmitter is enabled to transmit a set of multiple carrier frequencies, where the transmitter is configured to transmit on one frequency chosen from a sub-set of multiple carrier frequencies from the set of multiple carrier frequencies. The sub-set of multiple carrier frequencies corresponds to the group to which the mobile unit is assigned. The receiver is configured to receive and demodulate the sub-set of multiple carrier frequencies and the controller configures the receiver to receive and demodulate the sub-set of multiple carrier frequencies that is assigned to the group.

Abstract: A multi-channel communication device for transmitting on a first frequency band or a second frequency band is disclosed. The multi-channel communication device may include a first transceiver operating at the first frequency band, a second transceiver operating at the second frequency band, and a controller in signal communication with the first transceiver and the second transceiver, wherein the controller may be configured to determine whether the first transceiver and the second transceiver are in operation.

Abstract: In general, a mobile unit for communicating with other mobile units assigned to a group within a Multipoint Voice Network (“MVN”) having a plurality of groups is shown. The mobile unit may include transmitter, receiver, and controller. The transmitter is enabled to transmit a set of multiple carrier frequencies, where the transmitter is configured to transmit on one frequency chosen from a sub-set of multiple carrier frequencies from the set of multiple carrier frequencies. The sub-set of multiple carrier frequencies correspond the group. The receiver is configured to receive and demodulate the sub-set of multiple carrier frequencies and the controller configures the receiver to receive and demodulate the sub-set of multiple carrier frequencies that is assigned to the group.

Abstract: A collapsible electro-acoustic transducer system (“CETS”) is described. The CETS system may include a base housing with at least one electro-acoustic transducer, where the base housing includes a base housing top and a base housing bottom, and a movable housing having at least one electro-acoustic transducer, where the movable housing is movably attached to the base housing. The CETS may also include an attaching element movably attaching the movable housing to the base housing, where the movable housing is configured to collapse within the base housing.