to occur in sequence as subscripted at regular intervals with pulse q 1 marking the beginning and end of each time delay period t d to illustrate applicant 39 s improvement the pole electrode 12 of an spdt switch is shown connected to the input terminal of the capacitor connected to the first and every odd lettered i e a or c set of detectors a first closed throw electrode 13 of the spdt switch is connected to the input terminal of the capacitor in the high resolution state shown the detector array functions as required for machine operations in atr systems the open throw electrode 14 of the spdt switch is connected to the input of a pulse delay line 17 which provides a total time delay of t d the output of this delay line is connected to the input electrode 18 of the next capacitor 19 in the following even lettered set when the spdt switches are thrown to their low resolution states the current pulse from detector a 1 arrives at the input terminal 18 at the same time as a pulse from detector b 1 this same relationship occurs for all pulses from diodes a and b with matching subscripts it also occurs for pulses from diodes c and d and all such basic sequential pairs which constitute the remainder of each row in.