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- Nachgewiesen in: USPTO Patent Applications
- Sprachen: English
- Document Number: 20220187436
- Publication Date: June 16, 2022
- Appl. No: 17/603401
- Application Filed: April 16, 2020
- Claim: 1. A method for estimating a range of a moving target, the method comprising: emitting, from a target, a first ultrasound signal T, wherein the first ultrasound signal T is generated based on a first differential Zadoff-Chu sequence x; receiving, at a receiver, a second ultrasound signal R, which corresponds to the first ultrasound signal T, wherein the second ultrasound signal R includes a second differential Zadoff-Chu sequence y; correlating the first ultrasound signal T with the second ultrasound signal R to calculate an initial time of flight estimate {circumflex over (τ)}corr; and calculating an initial range estimate {circumflex over (d)}corr by multiplying the initial time of flight estimate {circumflex over (τ)}corr with a speed of sound c, wherein a differential Zadoff-Chu sequence is different from a Zadoff-Chu sequence.
- Claim: 2. The method of claim 1, wherein the first and second differential Zadoff-Chu sequences are periodic, with a period of N if N is odd and not divisible by 3, 3N if N is odd and divisible by 3, 4N if N is even and either (2N−1) or (N−1) is divisible by 3, and 12N otherwise, where N is a length of the sequence.
- Claim: 3. The method of claim 1, wherein the first and second differential Zadoff-Chu sequences are exponentials having an exponent proportional to k−1, where k is a discrete-time under a Doppler condition.
- Claim: 4. The method of claim 1, wherein the exponents of the first and second differential Zadoff-Chu sequences are further proportional to k+1 and k and ⅓.
- Claim: 5. The method of claim 1, wherein the step of correlating further comprises: applying a differential sliding correlation rD that calculates a sum of a product made up of (1) a complex conjugate of the first differential Zadoff-Chu sequence, (2) the first differential Zadoff-Chu sequence modified with a correlation step m, (3) the second differential Zadoff-Chu sequence modified with a natural number n, and (4) a complex conjugate of the second differential Zadoff-Chu sequence modified with m and n.
- Claim: 6. The method of claim 5, further comprising: taking an absolute value of the differential sliding correlation rD to find a maximum, which corresponds to the initial time of flight estimate {circumflex over (τ)}corr.
- Claim: 7. The method of claim 1, further comprising: calculating a relative Doppler shift {circumflex over (Δ)} for a segment; and resampling the second ultrasound signal with 1+{circumflex over (Δ)} to obtain a corrected second ultrasound signal.
- Claim: 8. The method of claim 7, further comprising: estimating a phase shift between the first ultrasound signal and the corrected second ultrasound signal.
- Claim: 9. The method of claim 8, further comprising: estimating a range refinement {circumflex over (Δ)}d by dividing the estimated phase shift by an associated frequency bin, and multiplying a result of the dividing by the speed of sound.
- Claim: 10. The method of claim 9, further comprising: calculating a refined range {circumflex over (d)} by adding the estimated range refinement {circumflex over (Δ)}d to the initial range estimate {circumflex over (d)}corr.
- Claim: 11. The method of claim 10, further comprising: performing a minimum refinement variance search.
- Claim: 12. A system for estimating a range of a moving target, the system comprising: the target, which is configured to emit a first ultrasound signal T, wherein the first ultrasound signal T is generated based on a first differential Zadoff-Chu sequence x; a receiver configured to receive a second ultrasound signal R, which corresponds to the first ultrasound signal T, wherein the second ultrasound signal R includes a second differential Zadoff-Chu sequence y; and a computing device connected to the receiver and configured to, correlate the first ultrasound signal T with the second ultrasound signal R to calculate an initial time of flight estimate {circumflex over (τ)}corr, and calculate an initial range estimate {circumflex over (d)}corr by multiplying the initial time of flight estimate {circumflex over (τ)}corr with a speed of sound, wherein a differential Zadoff-Chu sequence is different from a Zadoff-Chu sequence.
- Claim: 13. The system of claim 12, wherein the first and second differential Zadoff-Chu sequences are periodic, with a period of N if N is odd and not divisible by 3, 3N if N is odd and divisible by 3, 4N if N is even and either (2N−1) or (N−1) is divisible by 3, and 12N otherwise, where N is a length of the sequence.
- Claim: 14. The system of claim 12, wherein the first and second differential Zadoff-Chu sequences are exponentials having an exponent proportional to k−1, where k is a discrete-time under a Doppler condition.
- Claim: 15. The system of claim 14, wherein the exponents of the first and second differential Zadoff-Chu sequences are further proportional to k+1 and k and ⅓.
- Claim: 16. The system of claim 12, wherein the computing device is further configured to: apply a differential sliding correlation rD that calculates a sum of a product made up of (1) a complex conjugate of the first differential Zadoff-Chu sequence, (2) the first differential Zadoff-Chu sequence modified with a correlation step m, (3) the second differential Zadoff-Chu sequence modified with a natural number n, and (4) a complex conjugate of the second differential Zadoff-Chu sequence modified with m and n.
- Claim: 17. The system of claim 16, wherein the computing device is further configured to: take an absolute value of the differential sliding correlation rD to find a maximum, which corresponds to the initial time of flight estimate {circumflex over (τ)}corr.
- Claim: 18. The system of claim 12, wherein the computing device is further configured to: calculate a relative Doppler shift {circumflex over (Δ)} for a segment; and resample the second ultrasound signal with 1+{circumflex over (Δ)} to obtain a corrected second ultrasound signal.
- Claim: 19. The system of claim 18, wherein the computing device is further configured to: estimate a phase shift between the first ultrasound signal and the corrected second ultrasound signal; estimate a range refinement {circumflex over (Δ)}d by dividing the estimated phase shift by an associated frequency bin, and multiplying a result of the dividing by the speed of sound; and calculate a refined range {circumflex over (d)} by adding the estimated range refinement {circumflex over (Δ)}d to the initial range estimate {circumflex over (d)}corr.
- Claim: 20. A system for generating a coded ultrasound signal, the system comprising: a target, which is configured to emit a first ultrasound signal T, wherein the first ultrasound signal T is generated based on a first differential Zadoff-Chu sequence x; and a receiver configured to receive a second ultrasound signal R, which corresponds to the first ultrasound signal T, wherein the second ultrasound signal R includes a second differential Zadoff-Chu sequence y, wherein a differential Zadoff-Chu sequence is different from a Zadoff-Chu sequence.
- Current International Class: 01; 01; 04
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