In a diversity receiving system for receiving modulated RF signals using an array of antennas and recovering information signals from the modulated signals, the information signal of the highest strength is selected to allow a connection to be established from a transmit site. Strength data of the selected signal is stored in a corresponding one of memory locations respectively mapped to the antennas. Strength data stored in the memory locations are analyzed. If none of the strength data exceeds a threshold value, a first alarm is given of the whole array of antennas. If at least one strength data exceeds the threshold, the memory locations are tested to see if there is at least one vacant memory location which contains no strength data. If such a vacant location exists, a second alarm is given of the antenna that is mapped to the vacant location. In a modified embodiment, the stored strength data are counted to produce a number of respective counts for the memory locations if at least one strength data exceeds the threshold value, and the difference between a maximum and a minimum value of the counts is determined. If the difference is greater than a predetermined value, the second alarm is given of the antenna that is mapped to the memory location having the minimum count value.