Coherent range and length resolution

Claim 2

A radar system for making precise determinations of target range and target length comprising: means for providing RF pulses which are separated by equal increments of frequency and time, means for transmitting said pulses, means for receiving reflections of said pulses from targets within a range interval of interest, means for demodulating said reflections with local signals to provide IF signals, said local signals comprising pulses of the same rate and frequency sequence as said transmitted pulses but delayed with respect thereto, and means for processing said IF signals to determine their relative phase shifts and to generate a precise measurement of range and length of targets within said range interval of interest.

Claim 3

A radar system for making precise determinations of target range and target length comprising: means for providing RF pulses which are separated by equal increments of frequency and time, means for transmitting said pulses, means for receiving reflections of said pulses from targets within a range interval of interest, means for demodulating said reflections with local signals to provide IF signals, said local signals comprising pulses of the same rate and frequency sequence as said transmitted pulses but delayed with respect thereto, and means for processing said IF signals to determine their relative phase shifts and to generate a precise measurement of range and length of targets within said range interval of interest.

Claim 4

A radar system for making precise determinations of target range and target length comprising: means for providing RF pulses which are separated by equal increments of frequency and time, means for transmitting said pulses, means for receiving reflections of said pulses from targets within a range interval of interest, means for demodulating said reflections with local signals to provide IF signals, said local signals comprising pulses of the same rate and frequency sequence as said transmitted pulses but delayed with respect thereto, and means for processing said IF signals to determine their relative phase shifts and to generate a precise measurement of range and length of targets within said range interval of interest.

Claim 5

A radar system for making precise determinations of target range and target length comprising: means for providing phase coherent RF pulses which are separated by equal increments of frequency and time, means for transmitting said pulses, means for receiving reflections of said pulses from targets within range intervals of interest, means for demodulating said reflections with local signals to provide coherent IF signals, said local signals comprising pulses separated by equal increments of frequency and time similarly to said transmitted pulses but delayed with respect thereto by an amount equal to the round trip signal transit time to the near edge of a range interval of interest, and means for processing said IF signals to determine their relative phase shifts and thus to generate precise measurements of targets within said range intervals of interest.

Claim 6

A radar system for making precise determinations of target range and target length comprising: means for providing phase coherent RF pulses which are separated by equal increments of frequency and time, means for transmitting said pulses, means for receiving reflections of said pulses from targets within range intervals of interest, means for demodulating said reflections with local signals to provide coherent IF signals, said local signals comprising pulses separated by equal increments of frequency and time similarly to said transmitted pulses but delayed with respect thereto by an amount equal to the round trip signal transit time to the near edge of a range interval of interest, and means for processing said IF signals to determine their relative phase shifts and thus to generate precise measurements of targets within said range intervals of interest.

Claim 7

A radar system substantially as claimed in claim 1 in which said means for providing RF pulses separated by equal increments of frequency and time includes, a source of multiple frequency RF signals which are separated in frequency by equal increments, and switching means for sampling said RF signals sequentially to provide pulses which are spaced apart both in time and in frequency by equal increments.

Claim 8

A radar system substantially as claimed in claim 1 in which said means for providing RF pulses includes, means for modulating RF pulses with highly stable signals.

Claim 9

A radar system substantially as claimed in claim 3 in which: said local sIgnals are derived from said source of multiple frequency RF signals by operation of additional switching means, and said local signals are delayed in time to permit said transmitted pulses to make their round trip to a range interval of interest and back before mixing with said local signals.

Claim 10

A radar system substantially as claimed in claim 1 in which said local signals are derived by securing samples of RF signals from said means for providing RF pulses and said samples are provided with a time delay equal to the time required for a round-trip by said RF pulses to a range interval of interest and back.

Claim 11

A radar system substantially as claimed in claim 1 and embodying means for compensating for high velocity targets in which: said means for providing RF pulses separated by equal increments of frequency includes provision that a series of pulses from O - N are separated by equal increments of rising frequency and a series following N and including pulse 2N are separated by increments of decreasing frequency, and said means for processing incorporates means to multiply IF pulses derived from said pulses 0 through N by IF pulses derived from said pulses N through 2N to provide a series of N coherent pulses free of errors due to high velocity of the targets.

Claim 12

A radar system substantially as claimed in claim 7 in which said means for compensating for high velocity targets includes: switching means for coupling said IF signals at frequency fi into adder means to insert the pulses into a delay loop, means in said delay loop to step up the frequencies of the first N pulses by an amount fs during each circulation in the loop until the first pulse ''''O'''' has the frequency fi + (N - 1)fs and the Nth received pulse ''''N-1'''' has the frequency fi, means to control the input circuits of said delay loop upon receipt of said (N+1)st pulse, which is pulse N, to step up the frequency of circulating pulses by fs, to insert pulse N into the loop at frequency fi, to multiply pulse N by itself and step the frequency of the resulting pulse up by (N + 1)fs to provide a pulse having the frequency fi + (N + 1)fs so that pulses having frequencies from fi through fi + (N + 1)fs are circulating in the loop, and means associated with said delay loop to reduce the frequencies of the pulses circulating in the loop by an amount fs during each circulation in the loop after pulse N has been received and to multiply each pulse as it reaches the frequency fi and step the frequency of the product up to f1 + (N + 1)fs until all the N + 1 through 2N pulses have been multiplied by the pulses N-1 through 0 to produce a plurality of N pulses in the loop separated by the frequency fs.

Claim 13

A radar system substantially as claimed in claim 1 including means for automatically correcting the effects of high velocity in a target including: means in said means for providing RF pulses to control the RF pulses so that each pulse from the first pulse to the Nth pulse is of successively higher frequency and each pulse from the Nth pulse to the 2Nth pulse is of successively lower frequency, and means in said means for processing said IF signals to store said IF signals corresponding to said first pulse to said Nth pulse and to multiply the stored signals by said IF signals corresponding to said Nth pulse through said 2Nth pulse, thereby to remove undesired effects of velocity which cause a deterioration of length resolution.

Claim 14

A radar system for making precise length measurements comprising: means for providing a first sequence of pulses separated by equal increments of frequency and time, means for modulating each of said first sequence of pulses, means for transmitting said first sequence of pulses as radar signals, means for providing a second sequence of pulses with each pulse separated in frequency and time from adjacent pulses in a similar manner to said first sequence of pulses, said last named means incorporating a time delay into said second sequence of pulses to provide delayed pulses, means for receiving reflections of said radar signals from targets, means for demodulating said radar signals by mixing them with said delayed signals to provide coherent IF signals, and means for processing said coherent IF signals to provide a precise measurement of length and range of each target.

Claim 15

A radar system for making precise length measurements comprising: means for providing a first sequence of pulses separated by equal increments of frequency and time, means for modulating each of said first sequence of pulses, means for transmitting said first sequence of pulses as radar signals, means for providing a second sequence of pulses with each pulse separated in frequency and time from adjacent pulses in a similar manner to said first sequence of pulses, said last named means incorporating a time delay into said second sequence of pulses to provide delayed pulses, means for receiving reflections of said radar signals from targets, means for demodulating said radar signals by mixing them with said delayed signals to provide coherent IF signals, and means for processing said coherent IF signals to provide a precise measurement of length and range of each target.

Claim 16

A radar system for making precise range and length measurements comprising: a source of plural RF signals which are separated by equal increments of frequency, first switching means for sampling each of said RF signals to provide a first sequence of pulses which are equally spaced from each other in time and in frequency, means for transmitting said pulses as radar signals, second switching means for sampling each of said RF signals in sequence to provide a sequence of delayed pulses which are equally spaced from each other in time and in frequency but delayed in time relative to said first sequence of pulses by an amount proportional to the round-trip time for radar signals to illuminate the near edge of a range-bin of interest, means for receiving said radar pulses reflected from targets within range-bins of interest, means for demodulating said reflected radar pulses with said delayed pulses to provide IF signals containing information concerning targets of interest, and means for processing said IF signals to provide accurate determinations of range to targets and lengths of targets.

Claim 17

A radar system for making precise range and length measurements comprising: a source of plural RF signals which are separated by equal increments of frequency, first switching means for sampling each of said RF signals to provide a first sequence of pulses which are equally spaced from each other in time and in frequency, means for transmitting said pulses as radar signals, second switching means for sampling each of said RF signals in sequence to provide a sequence of delayed pulses which are equally spaced from each other in time and in frequency but delayed in time relative to said first sequence of pulses by an amount proportional to the round-trip time for radar signals to illuminate the near edge of a range-bin of interest, means for receiving said radar pulses reflected from targets within range-bins of interest, means for demodulating said reflected radar pulses with said delayed pulses to provide IF signals containing information concerning targets of interest, and means for processing said IF signals to provide accurate determinations of range to targets and lengths of targets.

Claim 18

A radar system for making precise range and length measurements comprising: a source of plural RF signals which are separated by equal increments of frequency, first switching means for sampling each of said RF signals to provide a first sequence of pulses which are equally spaced from each other in time and in frequency, means for modulating each of said pulses, means for transmitting said pulses as radar pulses, second switching means for sampling each of said RF signals in sequence to provide a sequence of delayed pulses which are equally spaced from each other in time and in frequency but delayed in time relative to said first sequence of pulses by an amount equal to the roundtrip time for radar signals to illuminate the near edge of a range interval of interest, means for receiving said radar pulses reflected from targets within range intervals of interest, means for demodulating said reflected radar pulses with said delayed pulses to provide IF signals containing information concerning targets of interest, and means for processing said IF signals to provide accurate determinations of range to targets and determinations of lengths of targets.

Claim 19

A radar system for making precise range and length measurements comprising: a source of plural RF signals which are separated by equal increments of frequency, first switching means for sampling each of said RF signals to provide a first sequence of pulses which are equally spaced from each other in time and in frequency, means for modulating each of said pulses, means for transmitting said pulses as radar pulses, second switching means for sampling each of said RF signals in sequence to provide a sequence of delayed pulses which are equally spaced from each other in time and in frequency but delayed in time relative to said first sequence of pulses by an amount equal to the roundtrip time for radar signals to illuminate the near edge of a range interval of interest, means for receiving said radar pulses reflected from targets within range intervals of interest, means for demodulating said reflected radar pulses with said delayed pulses to provide IF signals containing information concerning targets of interest, and means for processing said IF signals to provide accurate determinations of range to targets and determinations of lengths of targets.

Claim 20

A radar system for making precise length measurements comprising: a source of distinct RF signals separated by equally spaced increments of frequency, first switching means for sequentially sampling said RF signals to provide a first sequence of RF pulses separated in time as well as frequency, a source of stabilized signals for use in modulating said first sequence of RF pulses, a transmitter for transmitting said phase coherent pulses as radar pulses, means for receiving reflections of said radar pulses from a selected range interval, second switching means incorporated with delay means for sequentially sampling said RF signals to provide a second sequence of RF pulses, said second sequence being delayed in time relative to the first by a time equal to the round trip time of the radar pulses to the first edge of the selected range interval, means for mixing said second sequence of RF pulses with a portion of said stabilized signals to provide a phase stable local train of pulses, a demodulating circuit for demodulating said reflections of radar pulses with said phase stable local train of pulses to form IF coherent pulse trains, and processing means responsive to IF coherent reference signals and to said IF coherent pulse trains to accurately determine phase relationships between the reference signals and each of said coherent pulse trains to determine precise range to and lengths of targets in the range interval of interest.

Claim 21

A radar system for making precise length measurements comprising: a source of distinct RF signals separated by equally spaced increments of frequency, first switching means for sequentially sampling said RF signals to provide a first sequence of RF pulses separated in time as well as frequency, a source of stabilized signals for use in modulating said first sequence of RF pulses, a transmitter for transmitting said phase coherent pulses as radar pulses, means for receiving reflections of said radar pulses from a selected range interval, second switching means incorporated with delay means for sequentially sampling said RF signals to provide a second sequence of RF pulses, said second sequence being delayed in time relative to the first by a time equal to the round trip time of the radar pulses to the first edge of the selected range interval, means for mixing said second sequence of RF pulses with a portion of said stabilized signals to provide a phase stable local train of pulses, a demodulating circuit for demodulating said reflections of radar pulses with said phase stable local train of pulses to form IF coherent pulse trains, and processing means responsive to IF coherent reference signals and to said IF coherent pulse trains to accurately determine phase relationships between the reference signals and each of said coherent pulse trains to determine precise range to and lengths of targets in the range interval of interest.

Claim 22

A high resolution radar comprising: means for generating a plurality of carrier signals separated in time and frequency by corresponding equal increments, means for modulating samples of said carrier signals to provide radar pulses separated precisely in time and frequency, means for transmitting said radar pulses, means for supplying additional samples of the carrier signals delayed in time by an amount equal to the round trip time required for a radar signal to reach and return from the closest edge of a range interval of interest, means for modulating said additional samples of said carrier signals to provide local signals separated precisely in time and frequency, means for receiving said reflections of radar pulses, means for demodulating the reflections of said radar pulses by use of said local signals to provide coherent if signals, and means for processing said coherent IF signals to provide signals expressive of finely resolved length and range.

Claim 23

A high resolution radar comprising: means for generating a plurality of carrier signals separated in time and frequency by corresponding equal increments, means for modulating samples of said carrier signals to provide radar pulses separated precisely in time and frequency, means for transmitting said radar pulses, means for supplying additional samples of the carrier signals delayed in time by an amount equal to the round trip time required for a radar signal to reach and return from the closest edge of a range interval of interest, means for modulating said additional samples of said carrier signals to provide local signals separated precisely in time and frequency, means for receiving said reflections of radar pulses, means for demodulating the reflections of said radar pulses by use of said local signals to provide coherent if signals, and means for processing said coherent IF signals to provide signals expressive of finely resolved length and range.

Claim 24

A high resolution radar comprising: means for generating a plurality of RF pulses borne on carrier signals and separated both in time and frequency by corresponding equal increments, means for transmitting said RF pulses as radar signals, means for receiving reflections of said radar signals, means for providing local signals having the same sequence of time and frequency as said carrier signals, the beginning of the sequence of said local signals being delayed for a period equal to the time for reflection of the radar signals to be received, means for employing said local signals to demodulate said reflections of the radar signals and provide coherent IF signals, and means for processing said coherent IF signals to provide signals expressive of finely resolved length and range.

Claim 25

A high resolution radar comprising: means for generating a plurality of RF pulses borne on carrier signals and separated both in time and frequency by corresponding equal increments, means for transmitting said RF pulses as radar signals, means for receiving reflections of said radar signals, means for providing local signals having the same sequence of time and frequency as said carrier signals, the beginning of the sequence of said local signals being delayed for a period equal to the time for reflection of the radar signals to be received, means for employing said local signals to demodulate said reflections of the radar signals and provide coherent IF signals, and means for processing said coherent IF signals to provide signals expressive of finely resolved length and range.

Claim 26

A high resolution radar comprising: a source of carrier signals of stable frequencies separated by a fixed frequency difference Delta F and a fixed time separation T, a source of IF coherent reference signals, a source of stabilized local oscillator signals, means for mixing said carrier signals, said IF coherent reference signals and said stabilized local oscillator signals to provide RF signals in the form of pulses separated in time by equal periods T and by the fixed frequency difference Delta F, means for transmitting said RF signals as radar signals, means for receiving signals constituting reflections of said radar signals, means for demodulating said signals representing reflections, and means for coherently integrating said demodulated signals representing reflections to provide a refined measurement of range and length.

Claim 27

A high resolution radar comprising: a source of carrier signals of stable frequencies separated by a fixed frequency difference Delta F and a fixed time separation T, a source of IF coherent reference signals, a source of stabilized local oscillator signals, means for mixing said carrier signals, said IF coherent reference signals and said stabilized local oscillator signals to provide RF signals in the form of pulses separated in time by equal periods T and by the fixed frequency difference Delta F, means for transmitting said RF signals as radar signals, means for receiving signals constituting reflections of said radar signals, means for demodulating said signals representing reflections, and means for coherently integrating said demodulated signals representing reflections to provide a refined measurement of range and length.