| ABSTRACT:
A method for generating a sequence of short radar pulses and a method
plus apparatus for detecting those same short pulses when backscattered,
even though they are heavily distorted by a target and have additive noise
and unwanted signals superimposed on them. The method applies to pulses
of long or short duration, including durations of 1 nanoseconds (1 ns)
or less. The pulses are transmitted without the fine structure marking
of a sinusoidal wave carrier, but organized into a coarse structure that
results from incorporating them within a highly unconventional type of
character, wherein a plurality of positive-going and negative-going pulses
are transmitted such that each pulse is spaced apart from its neighbors.
Each pulse is short, so the return signal is highly distorted. The sequence
of positive-going and negative-going pulses are organized into a pattern
of non-contiguous pulses that constitute a new type of "character", which
may be thought of as a "spaced-apart-character". This "spaced-apart-character"
is organized into a large coarse structure marking, so that a) the total
transmitted energy is large, b) a receiver can selectively distinguish
the wanted return signal from noise and unwanted signals, and c) reflections
from targets longer than L=.DELTA.tc/2 are rejected. |