Abstract: A method, and apparatus for accomplishing the method, for determining the frequency of an RF signal that operates by sequentially applying a received RF signal to sequentially selected individual filters having predetermined frequency pass bands and comparing the magnitudes of the filtered and unfiltered RF signals. The frequency of the RF signal is determined as being within the predetermined frequency pass band of a filter that outputs a largest magnitude output signal relative to the magnitude of the RF signal. Signals of insufficient magnitude are not processed by the system.

Abstract: A three input comparator facilitates the comparison of a signal to the greater of two different reference voltages in a manner which mitigates propagation delay. A first differential pair of transistors facilitates comparison of the two reference voltages to one another, while second and third differential pairs of transistors facilitate comparison of the signal to the higher of the two reference voltages.

Abstract: A vehicle having a plurality of antennas each in association with a communications transmitter device disposed within the vehicle to thereby provide multiple signal transmission sites. At least one antenna is disposed substantially at a top site of the vehicle and at least one antenna is disposed substantially at a bottom site of the vehicle, thus providing antenna coverage irrespective of the spatial orientation of the vehicle. The invention includes a communications system employing a multiplicity of antenna sites as well as methodology for providing a communication link from a vehicle to a receiving site by incorporating the communications system. In this manner, vehicle occupants are provided with a communications link from the vehicle, irrespective of the position of the vehicle.