The effects of flipper bands on adult survival rate and reproduction in the Royal Penguin

In radio ranging from a mobile station and a plurality of base stations, different pulse position codes are transmitted from the mobile station in sequence, one code for each base station. Identical reply pulse position codes are transmitted from each base station in response to receipt of one of the unique codes. In response to receipt of each reply code, a plurality of trains of listening intervals, one for each base station, are initiated each being dependent upon the time of receipt of a reply code from a base station. A train of uniformly time spaced ranging pulses is then transmitted after receipt of a reply pulse code from the base stations. The transporting of ranging pulses from each base station is enabled in a sequence between base stations responsive to successive ranging pulses in the train.