Abstract: The method provides talk around in an OFDMA communication system by sending a talk around request from a subscriber unit to a base unit. At the subscriber unit a RSSI (received signal strength indication) of a signal received from the base unit is determined and sent back to the base unit. In the base unit the RSSI is compared to a predetermined window. If the RSSI is above the window, the request from the subscriber unit is denied. If the RSSI is within the window, a sub-channel of the OFDMA communication system and a power level are assigned to the subscriber unit, the subscriber unit thereby going into talk around mode. If the RSSI is below the window, the subscriber unit does not respond and the subscriber unit goes into a direct communication mode independent of the OFDMA communication system.

Abstract: An exceptionally wideband, synthesizer controlled voltage controlled oscillator is disclosed which is characterized by a plurality of pin diode frequency shift networks which, when actuated shifts the frequency of the oscillator in selectable binary steps within a wide frequency range in the order of 48 MHz. Special means are included to prevent undesireable parasitic oscillation modes when such frequency shift networks are in an inactuated, switched off mode. A multiple varactor tuning circuit is provided for selecting a precise frequency within a relatively narrow frequency band on the order of 6 MHz.