Abstract: A wireless method and apparatus for late entry in frequency hopping systems that, during call setup, computes a random permutation sequence through a hop set of frequencies, chooses preamble frequencies to omit data thereon in lieu of preamble data, and swaps frequencies in the random permutation sequence such that synchronization frequencies lie next to the preamble frequencies with an expected delay such that late entrants can join. The wireless method and apparatus meets the FCC requirement of maintaining a pseudorandom hopping pattern and equal distribution of all frequencies in a hop set while guaranteeing late entry and having no effect on battery performance of radios.

Abstract: A wireless method and apparatus for late entry in frequency hopping systems that, during call setup, computes a random permutation sequence through a hop set of frequencies, chooses preamble frequencies to omit data thereon in lieu of preamble data, and swaps frequencies in the random permutation sequence such that synchronization frequencies lie next to the preamble frequencies with an expected delay such that late entrants can join. The wireless method and apparatus meets the FCC requirement of maintaining a pseudorandom hopping pattern and equal distribution of all frequencies in a hop set while guaranteeing late entry and having no effect on battery performance of radios.

Abstract: A method for call setup in an asynchronous frequency hopping digital two-way communication system includes transmitting in adjacent time slots, by a caller device, a preamble slot over a first unique fixed frequency selected from a frequency hopset and a synchronization slot over a second unique fixed frequency selected from the frequency hopset. Further, the method includes one or more target devices transmitting an acknowledgement signal upon receiving the preamble slot over the first unique fixed frequency and the synchronization slot over the second unique fixed frequency, and followed by the caller device establishing the data communication link between the caller device and the one or more target devices over at least one random frequency selected from the frequency hopset, in response to receiving the acknowledgement signal from the one or more target devices.

Abstract: A method for call setup in an asynchronous frequency hopping digital two-way communication system includes transmitting in adjacent time slots, by a caller device, a preamble slot over a first unique fixed frequency selected from a frequency hopset and a synchronization slot over a second unique fixed frequency selected from the frequency hopset. Further, the method includes one or more target devices transmitting an acknowledgement signal upon receiving the preamble slot over the first unique fixed frequency and the synchronization slot over the second unique fixed frequency, and followed by the caller device establishing the data communication link between the caller device and the one or more target devices over at least one random frequency selected from the frequency hopset, in response to receiving the acknowledgement signal from the one or more target devices.

Abstract: A technique for activating a transmit mode of a communication device (100) is provided encompassing the steps of generating a light signal on an outer surface of the communication device; inhibiting the light signal; and activating the transmit mode of the communication device in response to the light signal being inhibited. A communication device (100) operating in accordance with this technique includes a light transmitting device (108); and a sensor (110) for sensing light generated by the light transmitting device, the sensor disabling a transmit mode when light is detected and enabling a transmit mode when light is inhibited.

Abstract: A receiver (600) uses a scanning technique (100) to minimize scan time. An initial bandwidth setting is selected that covers multiple channel frequencies (106). A signal detection step (108) is performed looking for channel activity. As channel activity is detected, the bandwidth of a baseband filter (628) is narrowed (140, 146). The radio remains programmed to the same channel while the bandwidth is varied. Once the last signal detection with the narrowest possible bandwidth setting has been determined (144, 150, 152) the radio is programmed to that channel. Thus, more than one channel frequency is capable of being scanned without reprogramming the radio to a new channel for each scan.

Abstract: A receiver (600) uses a scanning technique (100) to minimize scan time. An initial bandwidth setting is selected that covers multiple channel frequencies (106). A signal detection step (108) is performed looking for channel activity. As channel activity is detected, the bandwidth of a baseband filter (628) is narrowed (140, 146). The radio remains programmed to the same channel while the bandwidth is varied. Once the last signal detection with the narrowest possible bandwidth setting has been determined (144, 150, 152) the radio is programmed to that channel. Thus, more than one channel frequency is capable of being scanned without reprogramming the radio to a new channel for each scan.

Abstract: A receiver (100) provides dual band features by providing two signal paths (106, 108) off an antenna (102), one for UHF operation (106) and one for VHF operation (108). The two signals paths (106, 108) feed into a single broadband input (124) of a direct conversion receiver (114). The UHF path (106) utilizes UHF front end circuitry (110) while the VHF path (108) is implemented with a loading/isolator circuit (120) and a matching circuit (122). The loading/isolator circuit (120) loads the antenna (102) and isolates UHF signals while the matching circuit (122) provides a match between the loading isolator circuit (120) and the direct conversion recover (114). Selectable matching circuitry (126, 128) and selectable VCO circuitry (132, 134) configures the direct conversion receiver for the UHF or VHF mode of operation.

Abstract: A phase noise optimization circuit (208) minimizes phase noise for a voltage controlled oscillator (VCO) (202). Control circuitry (214) locates a minimum phase noise region for VCO operation based on the slope of the VCO's changing control voltage (206) versus changing bias voltage (204) for a bias voltage range. The control circuitry (214) then adjusts the bias input so that the VCO operates in a region of minimum phase noise.

Abstract: A self-tuning VCO (116) receives a control voltage input (Vcont) (114) and an adjustable programmable voltage (Vadj) (122) and provides optimized locked conditions even under variations in temperature. A radio temperature is measured and stored (204) while Vadj (122) is initialized and stepped and Vcont (114) attempts to lock the VCO on frequency. Once a locked condition is achieved, the Vcont (114) is monitored to determine if it falls within a predetermined voltage range. If a non-optimized condition is detected, then the Vadj (122) is automatically adjusted until the VCO (116) becomes locked with a Vcont which falls within the predetermined voltage range. When a locked condition is achieved, the radio temperature is monitored and compared (212) to the original stored temperature (204). If a temperature threshold limit is reached (216) then the VCO is re-checks itself for a locked condition and re-optimizes itself to accommodate for the variations in temperature.

Abstract: An oscillator (100) includes a tank circuit (102) coupled to a an active circuit (108). The feedback (104) provides the necessary feedback between the tank and the active circuit necessary for oscillation. The active circuit (108) is biased via a biasing circuit (106) and coupled out to a load via an external coupling (110). The active circuit (108) includes two transistors (124, 126) coupled to each other in a cascode configuration. Transistor (126) provides the collector current for transistor (124) while preventing it from entering saturation prematurely. The biasing circuit (106) provides sufficient current drain for the transistor (126) in order to provide for optimum phase noise and bandwidth performance of the oscillator 100.

Abstract: A frequency modulator (100) is provided which includes a VCO (200) having a modulation varactor (122) coupled to its output (128). The VCO (200) includes a resonator stage (112) coupled to an amplifier stage comprising a transistor (118). Coupling of the varactor (122) and the resonator stage (112) is provided via the phase collector capacitance (C.mu.) of the transistor (118).