output signals e1 to e12 the number of output is equal to the number of distance ranges the clock signal cyclically switches the control unit from one output to another the output signals e1 to e12 are used to control the oscillator bank 10 fig2 this control causes the input signals of the second mixer 9 to be mixed cyclically at the clock rate 2 khz with the various frequencies of the oscillator bank 10 which are allotted each to a discrete distance increment on fig5 each output signal of the control unit 65 which is essentially an electronic commutator is also applied to and gates 66 1 through 66 12 the signals sdv and se are applied to an and gate 61 the output signal of this and gate 61 is applied to the bank of and gates 66 1 through 66 12 and also to a flip flop 62 the flip flop 62 is followed by a one shot multivibrator 63 the time constant of the one shot multivibrator 63 is 50 ms typically and as such is equal to the time needed to evaluate the doppler shift the output signal of the one shot multivibrator 63 is passed to the inverting input of the inhibit gate 64 as long as this signal is present at the inverting input of this inhibit gate 64 the control unit 65 does not switch search to enable the next output the search is not continued until the one shot multivibrator 63 has returned to its stable state the flip flop 62 is reset by the last output signal e12 of the control circuit 65 by the connection to r of 62 this insures that no relative speeds other than that of the.