Ranging system including apparatus for forming directional characteristics at the receiving end and for correlating

In an apparatus for the formation of beams characteristics at the receiving end of a ranging system operating according to the reflected-beam ranging technique with acoustical or electromagnetic waves and for correlating the received signals, said apparatus including a plurality of transducers arranged in rotational symmetry in a transmitting-receiving plane, a transmitter for providing pulse-shaped wave energy to be transmitted by said transducers and a transmitting-receiving switch for selectively connecting said transducers to said transmitter to cause the transmission of wave energy or, in order to evaluate the reflected energy, to a scanner means for repeatedly interrogating the received signals in succession during one reflected-beam ranging period, each switch position of said scanner being associated with one directional angle and each interrogation cycle covering all transducers being associated with one directional angle revolution;

• the improvement comprising:
• a two-dimensional light producing means, responsive to the output from said scanner means, for producing a light-wave output with an intensity or phase distribution dependent on the directional angle in one dimension and dependent on the time of reception of the received signals within each ranging period in the other dimension, whereby the wavefront of the lightwave output is modulated by the successively scanned received signals;
• a series-connected, two-dimensional optical correlator means, having its input connected to the output of said light producing means and containing a reference disc, as the reference function of the correlator, with a transmission function which corresponds to directional characteristic for a transmitted signal received without interference from a reference direction, for correlating the input signal thereto with said reference function;
• and a two-dimensional display device connected in series with the output of said optical correlator means.