Abstract: A voltage control oscillator (400) includes a tank circuit (402) wihch includes a control input (118). The VCO (400) further includes a feedback section (106) which includes a transistor (108). The feedback circuit (106) further includes a feedback compensation circuit 420 which compensates the feedback ratio of the feedback circuit (106) over changes in frequency of operation in order to provide for a substantially constant open loop gain. The improved VCO (400) provides for fairly constant current drain over changes in frequency as well as lower power output variations and flatter Side Band Noise Ratio response over frequency.

Abstract: A voltage level shifting circuit (100) comprises an input port (160) and output terminal (162). The voltage level shifting circuit (100) further comprises a voltage translation circuit which generates first and second voltage levels, both of which are related to the input reference voltage and which both vary with variations in the input voltage. A control circuit (158) controls which of the two voltage levels produced by the voltage translation circuit is presented at output terminal (162), depending on the voltage level at the control circuit input port (168).

Abstract: A centralized communication system controller (102) measures and stores a historical record of each subscriber unit's communication activity. By examining this historical record, the controller predicts the subscriber unit's communication activity over a future time interval. A code based upon this prediction is transmitted to the subscriber unit (110), which causes the subscriber unit to enter an energy saving mode and deactivate (208) non-essential circuits for a time period represented by the code. In this way, the duration of the "sleep" interval may be optimally varied based upon the subscriber unit's communication history. In another aspect of the invention, unexpected messages for a subscriber unit in the energy saving mode are stored (114) electronically until the conclusion of the "sleep" interval. This message storing function enhances system efficiency when the subscriber unit's communication history does not correlate with actual commuication traffic.

Abstract: An environmentally sealed battery connector (100) includes a battery contact member (102) having a battery contact location (108). Battery connector (100) also includes a resilient seal member (118) having a battery mating ridge (110) which compresses against battery (204) and environmentally seals the point of contact between battery (204) and battery contact location (108).

Abstract: A digital radio communication system includes a plurality of cells for providing two-way digital radio communication. Each of the cells utilizes communication frames having at least one inbound communication slot and at least one outbound communication slot. The frames of each cell are of uniform length. At least some of the cells have different bit rates than other cells. Information about the contiguous cells is provided to the radios operating within a cell. The radio includes a memory for storing information on adjacent cells and the radio can evaluate the signal of adjacent cells for determining an appropriate cell for hand-off purposes.

Abstract: A two-way radio includes a receiver having a squelch circuit for determining if a communication channel is available. A transmitter is provided for transmitting voice messages on the channel. When the communication channel is available, voice signals are directed from a microphone to the transmitter for transmission. When the communication channel is not available, the voice signals are automatically directed to a digitizer there they are digitized. The digitized voice signals are stored in a memory for later transmission when the channel becomes available.

Abstract: A vehicular repeater interrupts the repeated audio and a timing signal that is transmitted to the portable. The timing signal is used by the portable to determine when the vehicular repeater will next interrupt the repeated information. Accordingly, the portable synchronizes its transmission of a signal to coincide with the next interruption. If no transmission is desired, the portable operates to mute the portable's speaker during the interruption to prevent noise bursts. Upon the initial recipt of a portable+s transmission signal, the vehicular repeater extends the interruption interval to verify the portable's transmission signal.

Abstract: A communication device (10) measures and compares (16,18) the ambient sound level of its environment. When the current ambient sound level exceeds a given threshold (52) the communication device automatically transmits (38) an information signal (44). Optionally, the communication devices's volume is also adjusted (26).