UNIQUE SPACE TIME ADAPTIVE SYSTEM (USS)

• US 20070200750A1
• Filed: 05/01/2006
• Published: 08/30/2007
• Est. Priority Date: 05/04/2005
• Status: Active Grant

• Current Assignee: Thomas Cataldo
• Original Assignee: Thomas Cataldo
• Inventors: Cataldo, Thomas
• Granted Patent: US 7,259,714 B1
• Time in Patent Office: Days
• US Class Current: 342/159
• CPC Class Codes: G01S 13/22 using irregular pulse repetition frequency G01S13/12 takes precedence
• CPC Class Codes: G01S 13/5246 post processors for coherent MTI discriminators, e.g. residue cancellers, CFAR after Doppler filters
• CPC Class Codes: G01S 13/9064 Inverse SAR [ISAR]
• CPC Class Codes: G01S 2013/0254 Active array antenna

Abstract

A method of detecting radar returns and measuring their parameters with or without clutter present and no clutter cancellation employed which includes transmitting at least one pulse; processing the returns surpassing a threshold detected in one range azimuth bin and by processing and separating out the returns based on their different range and azimuth. Another method includes transmission of many pulses and has minimum of one channel return surpassing detected threshold, which is detected in one range Doppler bin. The method also includes processing and thereby separating out the returns based on their different radial velocity and or azimuth and comparing the returns to a database of expected returns and adaptively processing returns that do not correspond to the expected returns. The method identifies the non-corresponding returns as indicative of at least one of clutter, land sea interface, clutter discretes and antenna sidelobe returns each without utilizing clutter cancellation.

Claims

1. A method employing an electronic array mounted on a moving platform and a unique space time adaptive system to detect a plurality of radar returns in a same bin and their parameters with or without clutter present, comprising the steps of:

a)transmitting at least one pulse;

b) receiving said plurality of radar returns from said at least one pulse over at least one channel;

c) processing said radar returns into range bins and determining whether said radar return surpasses a threshold;

d) processing said radar returns that exceed said threshold to determine radial velocity, range, and azimuth based upon each radar return of said plurality of radar returns having different radial velocity and azimuth without utilizing clutter cancellation; and

e) comparing said radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns, to identify said non-corresponding radar returns as indicative of at least one of clutter, a stationary target having moving elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation.

2. The method of claim 1 wherein said at least one pulse is a plurality of pulses,

said transmission occurs at a specific frequency, and

said at least one of a channel is a plurality of channels for synchronous reception.

3. The method of claim 1 further comprising the steps of:

a) transmitting required pulses;

b) processing many said N channels with as few as one or two pulses at a time; and

,

c) attaining additional said channel data.

4. The method of claim 2 further comprising the steps of:

a) receiving data pulse in a first channel and a second channel at a predetermined frequency;

b) receiving said pulse data 1 to M received in channel 1;

c) receiving said time pulse data in channel 2 delayed, wherein said delay is equal to the number of radar returns detected in a range Doppler bin;

d) over sampling said pulse data and said delayed pulse data in said range bin to a desired level;

e) zero filling said pulse data and said delayed pulse data to said desired level to increase pulse data and delayed pulse data frequency samples;

f) multiplying said pulse data and said delayed pulse data by a weighting function obtaining a spectrum of said pulse data and said delayed pulse data;

g) thresholding, in each range Doppler bin, said pulse data and said delayed pulse data for significant radar returns for a determination of the parameters including radial velocity, range, and azimuth without utilizing clutter cancellation;

h) if the number of said returns is three or less the solution is easily obtained analytically but if there is a sum of greater than three returns, since said solution is long and complicated an assist is utilizable by the association of determinations of the solutions in adjacent said range Doppler bins as being the same with said range Doppler under processing and where there is known said clutter return, its respective radial velocity is zero;

i) determining azimuth by processing another frequency sample;

j) determining range by processing another range sample;

k) repeating steps a) through f) to process another linear array for measuring height of a radar return;

l) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to frequency to calculate horizontal velocity and vertical tangential velocity;

m) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to range, to calculate a radial velocity;

n) delaying a change in phase and amplitude change due to height to calculate a vertical tangential velocity; and

,

o) comparing said radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns to identify said non-corresponding radar returns as indicative of clutter, a stationary target having moving elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation.

5. The method of claim 2 further comprising the steps of:

a) receiving pulse data in a first channel and a second channel at a predetermined frequency, wherein said pulse data, 1 to M is received in said first channel and

said first channel pulse data is delayed a rate equal to a number of expected radar returns, and said pulse data in said second channel is delayed from said first channel and said second channel is also delayed at said rate;

b) over sampling said pulse data and said delayed pulse data in said range bin to a desired level;

c) zero filling said pulse data and said delayed pulse data to said desired level to increase pulse data and delayed pulse data frequency samples;

c(i) multiplying said pulse-data and said delayed pulse data by a weighting function, obtaining a spectrum of said pulse data and said delayed pulse data;

d) thresholding, in each range Doppler bin, said pulse data and said delayed pulse data for significant radar returns for a determination of the parameter including radial velocity, range, and azimuth without utilizing clutter cancellation;

e) determining azimuth by processing another frequency sample;

f) determining range by processing another range sample;

g) repeating steps a) through f) to process another linear array for measuring height of a radar return;

h) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to frequency to calculate horizontal velocity;

i) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to range to calculate a radial velocity;

j) delaying a change in phase and amplitude change due to height to calculate a vertical tangential velocity; and

,

k) comparing said radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns to identify said non-corresponding radar returns as indicative of clutter, a stationary target having moving elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation.

6. The method of claim 3 further comprising the steps of:

a) receiving channel data in a first channel 1 to M and a second channel at a predetermined frequency, wherein said pulse 1 to pulse 2 of said first channel data is delayed a rate equal to a number of expected radar returns, and said channel data in said second channel is delayed D from said first channel and said second channel is also delayed at said rate;

b) over sampling said channel data and said delayed channel data in said range bin to a desired level;

c) zero filling said channel data and said delayed channel data to said desired level to increase channel data and delayed channel data frequency samples;

c(i) multiplying said channel data and said delayed channel data by a weighting function obtaining a spectrum of said channel data and said delayed channel data;

d) thresholding, in each range Doppler bin, said channel data and said delayed channel data for significant radar returns for a determination of the parameters including radial velocity, range, and azimuth without utilizing clutter cancellation;

e) determining Doppler peak by processing another space frequency sample;

f) determining range by processing another range sample;

g) repeating steps a) through f) to process another linear array for measuring height of a radar return;

h) delaying said channel data and said delayed channel data to determine an amplitude and phase change due to space frequency to calculate horizontal velocity

i) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to range to calculate a radial velocity;

j) delaying a change in phase and amplitude change due to height to calculate a vertical tangential velocity; and

,

k) comparing said radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns to identify said non-corresponding radar returns as indicative of clutter, a stationary target having moving elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation.

7. The method of claim 3 further comprising the steps of:

a) receiving data in a first channel and a second channel data;

b) receiving said channel data 1 to N received in channel 1;

c) receiving said time pulse data in channel 2 space delayed, wherein said delay is equal to the number of radar returns detected in a range azimuth bin;

d) over sampling said channel data and said delayed channel data in said range bin to a desired level;

e) zero filling said pulse data and said delayed data to said desired level to increase channel data and delayed channel data frequency samples;

f) multiplying said channel data and said delayed channel data by a weighting function, obtaining a spectrum of said channel data and said delayed channel data;

g) thresholding, in each range Doppler bin, said channel data and said delayed channel data for significant radar returns for a determination of the parameters including radial velocity, range, and azimuth without utilizing clutter cancellation;

h) if the number of said returns is three or less the solution is easily obtained analytically but if there is a sum of greater than three returns, since said solution is long and complicated an assist is utilizable by the association of determinations of the solutions in adjacent said range Doppler bins as being the same with said range Doppler under processing and where there is known said clutter return, its respective radial velocity is zero;

i) determining Doppler azimuth bin by processing another frequency sample;

j) determining range by processing another range sample;

k) repeating steps a) through f) to process another linear array for measuring height of a radar return;

l) delaying said channel data and said delayed channel data to determine an amplitude and phase change due to frequency to calculate horizontal velocity;

m) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to range to calculate an unambiguously radial velocity;

n) delaying a change in phase and amplitude change due to height to calculate a height; and

,

o) comparing and radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns to identify and non-corresponding radar returns as indicative of clutter, a stationary target having elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation.

8. The method of claim 2 further comprising the steps of:

a) interleaving said received data pulses synchronously with at least one interleaved channel at a predetermined frequency wherein said pulse data is delayed a number of times equal to an expected number of radar returns, said delayed pulse data is processed to a number of interleaved sets of data with a corresponding aperture change;

b) processing said interleaved sets of data independently, wherein a transmission array is centered between an aperture 1, and an aperture 2, said interleaved channels forming a beam width portion on each side of said transmission array, and changes in receive apertures corresponding to a change in receive data in the interleaved data with aperture change;

c) over sampling said pulse data and said delayed pulse data in said range bin to a desired level;

d) zero filling said pulse data and said delayed pulse data to said desired level to increase said pulse data and said delayed pulse data frequency samples;

e) delaying at least one interleaved channel a number of times equal to an expected number of radar returns, wherein said at least one interleaved pulses is multiplied by a weighting function and spectrum is processed;

f) thresholding, in each range Doppler bin, said pulse data and said delayed pulse data for significant radar returns, for a determination of the parameters including radial velocity, range, and azimuth without utilizing clutter cancellation;

g) if the number of said returns is three or less the solution is easily obtained analytically but if there is a sum greater than three returns, since said solution is long and complicated an assist is utilizable by the association of determinations of the solutions in adjacent said range Doppler bins as being the same with said range Doppler under processing and where there is known said clutter return, its respective radial velocity is zero;

h) processing two of said data and said data delayed, thereby determining the total phase response of all said returns from which is also calculated said return vectors;

i) calculation of the curve return ratio as a function of azimuth is determined, wherein the azimuth of each return may be made from real data of relatively high said clutter only at a number of azimuths of the receive antennas or there is determined a prior from said measured antenna patterns;

j) taking the ratio of the respective of said relatively high said clutter only return vectors and from a prior calculation of the curve return ratio as a function of azimuth there is compared to the ratio calculated from a solution of odd and even sets of data to determine the azimuth of each said return, from which the velocity of each return is determined;

k) determining peak Doppler by processing another frequency sample;

l) determining range by processing another frequency sample;

m) repeating steps a) through f) to process another linear array for measuring height of a radar return;

n) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to frequency to calculate horizontal velocity;

o) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to range to calculate a radial velocity;

p) delaying a change in phase and amplitude change due to height to calculate a vertical tangential velocity;

q) comparing said radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns to identify said non-corresponding radar returns as indicative of clutter, a stationary target having moving elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation; and

,

r) if more than a dual channel is available, process each said dual channel and correlate.

9. The method of claim 3 further comprising the steps of:

a) interleaving said received data pulses synchronously with at least one interleaved channel at a predetermined frequency wherein said channel data is delayed a number of times equal to an expected number of radar returns, and said delayed pulse data is processed to a number of interleaved said sets of data with a corresponding aperture change;

b) processing said interleaved sets of channel data independently, wherein a transmission array is centered between aperture 1, and aperture 2, said interleaved channels forming a beam width portion of each side of said transmission array, and changes in receive apertures corresponding to a change;

in receive data in the interleaved data with aperture change;

c) over sampling said pulse data and said delayed pulse data in said range bin to a desired level;

d) zero filling said channel data and said delayed channel data to said desired level to increase said channel data and said delayed channel data frequency samples;

e) delaying at least one interleaved channel a number of times equal to an expected number of radar returns, wherein said at least one interleaved pulses is multiplied by a weighting function and spectrum processed;

f) thresholding, in each range Doppler bin, said pulse data and said delayed pulse data for significant radar returns for a determination of the parameters including radial velocity, range, and azimuth without utilizing clutter cancellation;

g) if the number of said returns is three or less the solution is easily obtained analytically but if there is a sum greater than three returns, since said solution is long and complicated an assist is utilizable by the association of determinations of the solutions in adjacent said range Doppler bins as being the same with said range Doppler under processing and where there is known said clutter return, its respective radial velocity is zero;

h) processing two of said data and said data delayed, thereby determining the total phase response of all said returns from which is also calculated said return vectors;

i) calculation of the curve return ratio as a function of azimuth is determined, wherein the azimuth of each return may be made from real data of relatively high said clutter only at a number of azimuths of the receive antennas or optionally there is determined a prior from said measured antenna patterns;

j) taking the ratio of the respective of said relatively high said clutter only return vectors and from a prior calculation of the curve return ratio as a function of azimuth there is compared to the ratio calculated from a solution of odd and even sets of data to determine the azimuth of each return, from which the velocity of each said return is determined;

k) determining peak Doppler by processing another frequency sample;

l) determining range by processing another range sample;

m) repeating steps a) through f) to process another linear array when height of a radar return is to be measured;

n) delaying said channel data and said delayed channel data to determine an amplitude and phase change due to frequency to calculate horizontal velocity;

o) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to range to calculate precise range;

p) delaying a change in phase and amplitude change to determine height;

q) comparing said radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns to identify said non-corresponding radar returns as indicative of clutter, a stationary target having moving elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation; and

,

r) if more than dual channel is available, process each said dual channel and correlate.

10. The method of claim 2 further comprising the steps of:

a) receiving pulse data in a first channel and a second channel at a predetermined frequency, wherein said pulse data 1 to M is received in said first channel and

said first channel pulse data is delayed a rate equal to a number of expected radar returns, and said pulse data in said second channel is delayed D from said first channel and said second channel is also delayed at said rate;

b) over sampling said pulse data and said delayed pulse data in said range bin to a desired level;

c) zero filling said pulse data and said delayed pulse data to said desired level to increase pulse data and delayed pulse data frequency samples;

c(i) multiplying said pulse data and said delayed pulse data by a weighting function, thereby obtaining a spectrum of said pulse data and said delayed pulse data;

d) thresholding, in each range Doppler bin, said pulse data and said delayed pulse data for significant radar returns for a determination of amplitude and phase of each radar return;

e) determining by processing another frequency sample of precise peak of frequency;

f) determining range by processing another range sample precise range;

g) repeating steps a) through d) to process another linear array when precise amplitude and phase between linear arrays due to height of a radar return is to be measured;

h) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to frequency to calculate horizontal velocity and vertical tangential velocity;

i) delaying said pulse data and said delayed pulse data to determine and amplitude and phase change due to range to calculate an unambiguously radial velocity;

j) delaying a change in phase and amplitude change due to height to calculate a vertical tangential velocity; and

,

k) comparing said radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns to identify said non-corresponding radar returns as indicative of clutter, a stationary target having moving elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation.

11. The method of claim 2 further comprising the steps of:

a) receiving pulse data in a first channel and a second channel at a predetermined frequency, wherein said pulse data 1 to M is received in said first channel and said first channel pulse data is delayed a rate equal to a number of expected radar returns, and said pulse data in said second channel is delayed D from said first channel and said second channel is also delayed at said rate;

b) over sampling said pulse data and said delayed pulse data in said range bin to a desired level;

c) zero filling said pulse data and said delayed pulse data to said desired level to increase pulse data and delayed pulse data frequency samples;

c(i) multiplying said pulse data and said delayed pulse data by a weighting function obtaining a spectrum of said pulse data and said delayed pulse data;

d) said data is delayed a number of times equal to the expected number of said returns and each set of said delayed data is processing “

M”

data points in each simultaneous apertures of data, a portion of the beam width from the transmission array on each side;

e) determining by processing another frequency sample of precise peak of frequency;

f) determining range by processing another range sample precise range;

g) repeating steps a) through d) to process another linear array when precise amplitude and phase between linear arrays due to height of a radar return is to be measured;

h) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to frequency to calculate horizontal velocity and vertical tangential velocity;

i) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to range to calculate an unambiguously radial velocity;

j) delaying a change in phase and amplitude change due to height to calculate a vertical tangential velocity; and

,

k) comparing said radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns to identify said non-corresponding radar returns as indicative of clutter, a stationary target having moving elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation.

12. The method of claim 2 further comprising the steps of:

a) receiving pulse data in a first channel and a second channel at a predetermined frequency, wherein said pulse data 1 to M is received in said first channel and

said first channel pulse data is delayed a rate equal to a number of expected radar returns, and said pulse data in said second channel is delayed D from said first channel and said second channel is also delayed at said rate;

b) over sampling said pulse data and said delayed pulse data in said range bin to a desired level;

c) zero filling said pulse data and said delayed pulse data to said desired level to increase pulse data and delayed pulse data frequency samples;

c(i) multiplying said pulse data and said delayed pulse data by a weighting function obtaining a spectrum of said pulse data and said delayed pulse data;

d) said data is delayed a number of times equal to the expected number of said returns and each set of said delayed data is processing “

M”

data points in each simultaneous apertures of data, a portion of the beam width from the transmission array on each side;

e) determining by processing another frequency sample precise peak of frequency;

f) determining range by processing another range sample precise range;

g) repeating steps a) through d) to process another linear array when precise amplitude and phase between linear arrays due to height of a radar return is to be measured;

h) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to frequency to calculate horizontal velocity and vertical tangential velocity;

i) delaying said pulse data and said delayed pulse data to determine an amplitude and phase change due to range to calculate an unambiguously radial velocity;

j) delaying a change in phase and amplitude change due to height to calculate a vertical tangential velocity; and

,

k) comparing said radar returns to a database of expected radar returns and adaptively processing radar returns that do not correspond to the expected radar returns to identify said non-corresponding radar returns as indicative of clutter, a stationary target having moving elements, a land sea interface, clutter discretes, and antenna sidelobe returns without utilizing clutter cancellation.

13. The method of claim 2 further comprising:

employing an electronic scanned array and as few as one linear array and few as one pulse mounted on a moving platform in line with said platform motion and a unique space time adaptive system to detect returns and measure their parameters including velocity, azimuth and range accurately with said clutter and other said returns detected in the same range Doppler bin, where there is no said clutter cancellation of any kind is required such as said clutter covariance matrix, said clutter training data with or without knowledge aided said clutter, comprising the steps of;

a) receiving data transmission is a minimum of said one pulse of a pulsatory nature;

b) optionally over sampling in said range to desired level for all said data;

c) optionally zero fill said data to desired level to attain close frequency samples or all said data;

d) said data is delayed a number of times equal to the expected number of said returns and each set of said delayed data is processed wherein the improvement comprises;

e) each said data is delayed a number of times equal to the expected number of returns, each is multiplied by a weighting function and processed with a technique such as FFT for obtaining spectrum of said data;

f) in each said range Doppler bin processed there is thresholded to detect the presence of significant said returns, if so, contains an addition of all said returns and information such as range, radial velocity and azimuth, wherein this determination constitutes sets of simultaneous equations solved directly, with no clutter cancellation of any kind required, for each said return to determine its said velocity, azimuth and range;

g) if the number of said returns is three or less the solution is easily obtained analytically;

h) processing said data and said data delayed determining the total phase response of all returns from which is also calculated the return vectors;

i) determining the total phase response of all returns from which is also calculated the return vectors;

j) processing adjacent range azimuth bins and determining precise range;

k) optionally processing adjacent azimuth bin and Doppler bin where mover and clutter is processed with the same results in determining a solution'"'"'s precise azimuth;

l) optionally processing other linear arrays where mover and clutter are to be processed with same results in determining solutions and determining precise height;

m) processing a significant channel later as in steps i), j) and k) and obtain respectively azimuth change, and height change which determines azimuth change;

n) from unambiguous azimuth change there is determined azimuth;

o) from azimuth and total velocity determined the radial velocity is calculated;

p) thereby attaining the precise range, azimuth and height;

q) optionally processing another pulse if another pulse is obtained and obtaining another close solution;

r) optionally changing transmission frequency to avoid jamming and correlating results, wherein the transmission frequency is changed enough to avoid jamming, but not enough to affect the operation of system;

s) if there are significant returns of said returns, zero velocity and said return is said clutter, then non zero velocity of said return(s) are post processed to determine the type of said return such as mover, sidelobes, land sea interface, jamming, rotational motion targets, noise, jamming, others; and

,

t) whereby the return identification and accurate parameters of said returns have been determined without any clutter cancellation at all.