212 optical waveguide taps are located after each time delay segment 214 and each diverts a portion of the signal to a set of phase selectors 216 the diverted portions being appropriately delayed copies of the rf lightwave radar return signal the first tap 224 n is associated with the last digit of the code 218 n the second tap 224 n 1 with the second to last digit of the code 218 n 1 and so on the phase selector is preferably similar to the phase encoder discussed above and illustrated in fig2 and 3 for example in the phase encoder phase a is a short delay e g 0 1 nsec phase b is a longer delay e g 0 2 nsec and phase c is a longer still delay e g 0 3 nsec however for the phase selector phase a corresponds to the longest delay e g 0 3 nsec phase b is of medium delay e g 0 2 nsec and phase c is of shorter delay e g 0 1 nsec thus when used in the decoding preprocessor 220 each return phase selector 216 counteracts the time delay applied to that particular phase code interval by the transmit phase encoder 112 the result of this decoding is that all phase code intervals undergo the same total time delay when a combination of the transmitter and receiver imposed time delays is considered the duration u03b4t of the desired time delay and the length of the delay line 214 between taps 224 is determined by the desired compressed pulse width for example a 0 5 nsec compressed pulse width translates to a waveguide length of 10 cm in silica and 6 8 cm in lithium niobate.