Selective reception of carrier-free radar signals with large relative bandwidth
First Claim
1. In a radar transmission system having means for transmitting into a medium an electromagnetic signal comprising a plurality of positive-going and negative-going pulses, without a sinusoidal carrier as a fine structure marking, in a pattern of pulses that form a signal with coarse structure marking which is long compared to each of said pulses, the improvement comprising:
- means for supplying to the means for transmitting, a sequence of positive-going and negative-going pulses in a pattern of non-continguous pulses.
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Accused Products
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=Δtc/2 are rejected.
77 Citations
13 Claims
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1. In a radar transmission system having means for transmitting into a medium an electromagnetic signal comprising a plurality of positive-going and negative-going pulses, without a sinusoidal carrier as a fine structure marking, in a pattern of pulses that form a signal with coarse structure marking which is long compared to each of said pulses, the improvement comprising:
means for supplying to the means for transmitting, a sequence of positive-going and negative-going pulses in a pattern of non-continguous pulses. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of forming a radar signal comprising the steps of:
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generating positive-going and negative-going pulses without a sinusoidal carrier as a fine structure marking; generating a first pattern using said pulses to generate a first sequence of non-contiguous positive-going and negative-going pulses; generating a second pattern using said pulses to generate a second sequence of non-continguous positive-going and negative-going pulses; and transmitting the first pattern and then after a predetermined interval of time, transmitting the second pattern. - View Dependent Claims (8, 9, 10, 11)
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12. A radar receiving system comprising:
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means for selectively receiving a first pattern of non-contiguous positive-going and negative-going pulses as a radar signature, without a sinusoidal carrier as a fine structure marking, including means for producing an auto-correlation function of the first pattern to enhance detection of the radar signature and suppress unwanted signals and noise; means for receiving selectively a second pattern of non-continguous positive-going and negative-going pulses as a radar signature, without a sinusoidal carrier as a fine structure marking, including means for producing an auto-correlation function of the second pattern to enhance detection of the radar signature while simultaneously suppressing unwanted signals and noise; and means for summing the auto-correlation function of the first pattern with the auto-correlation function of the second pattern to produce an output signal with a ratio of the radar signature signal to the unwanted signals and noise that is greater than the received signal and auto-correlation functions taken individually. - View Dependent Claims (13)
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Specification