Relative time measurement system with nanosecond level accuracy
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G06F-019/00
G01R-035/04
G04G-007/00
출원번호
US-0318267
(2010-04-29)
등록번호
US-8880372
(2014-11-04)
우선권정보
IL-198489 (2009-04-30)
국제출원번호
PCT/IL2010/000346
(2010-04-29)
§371/§102 date
20111031
(20111031)
국제공개번호
WO2010/125569
(2010-11-04)
발명자
/ 주소
Rovinsky, Jacob
Solomon, Ernest
Hankin, Maxim
Kashani, Israel
출원인 / 주소
Israel Aerospace Industries Ltd.
대리인 / 주소
Oliff PLC
인용정보
피인용 횟수 :
0인용 특허 :
6
초록▼
A system for instantaneous and continuous nanosecond-level accuracy determination of a relative time offset between at least two non-collocated timing units, the system including at least two non-collocated timing units located at known positions, each timing unit comprising a frequency source and a
A system for instantaneous and continuous nanosecond-level accuracy determination of a relative time offset between at least two non-collocated timing units, the system including at least two non-collocated timing units located at known positions, each timing unit comprising a frequency source and a collocated receiver, each frequency source being disciplined at a frequency domain using a time source to generate corrections of the relative frequency drift between the frequency source and the time source.
대표청구항▼
1. A method for instantaneous and continuous determination of a relative time offset between non-collocated frequency sources having a relative frequency drift therebetween, said determination being carried out at a required nanosecond level accuracy, the method comprising: providing at least two no
1. A method for instantaneous and continuous determination of a relative time offset between non-collocated frequency sources having a relative frequency drift therebetween, said determination being carried out at a required nanosecond level accuracy, the method comprising: providing at least two non-collocated timing units located at known positions, each timing unit comprising a frequency source and a collocated receiver, wherein each said receiver is synchronized by a synchronization signal supplied by said frequency source and is operative to receive an external signal stream defining a time-line and to derive therefrom a stream of pseudo-range sample and integrated Doppler sample pairs, to generate, for each individual pair in at least a subset of said pairs, a periodic pulse synchronized with said frequency source, thereby to define a periodic pulse corresponding to said individual pair and to output each individual pair in said subset, simultaneously with the individual pair's corresponding periodic pulse;disciplining of frequency drift between the frequency sources at a frequency domain including computing, and applying to the frequency sources, corrections of a relative frequency drift between each frequency source and a single time source, said disciplining being limited by the following condition: the product of a duration of any time period extending between adjacent discrete points of time in a sequence of discrete points of time, times the sum of all frequency corrections effected during said time period divided by a frequency value characterizing the frequency sources, is at least one order of magnitude less than the required accuracy; anddetermining time offset between said non-collocated frequency sources at each discrete point of time in said sequence of discrete points of time. 2. A method according to claim 1 wherein said determining of time offset employs a common view time transfer procedure. 3. A method according to claim 1 wherein said time source comprises a GNSS time source. 4. A method according to claim 1 wherein said frequency value characterizing the frequency sources comprises a frequency of the frequency sources at a beginning point of said time period. 5. A system for instantaneous and continuous nanosecond-level accuracy determination of a relative time offset between at least two non-collocated timing units, the system comprising: at least two non-collocated timing units located at known positions, each timing unit comprising a frequency source and a collocated receiver,each said frequency source being disciplined at a frequency domain using a time source to generate corrections of the relative frequency drift between said frequency source and said time source so as to be limited by the following condition: the product of a duration of any time period extending between adjacent discrete points of time in a sequence of discrete points of time, multiplied by the sum of all frequency corrections effected during the time period and divided by a frequency value characterizing the frequency sources, is at least one order of magnitude less than the required accuracy,each said receiver being synchronized by a synchronization signal supplied by said frequency source and being operative to receive an external signal stream defining a time-line and to derive therefrom a stream of pseudo-range sample and integrated Doppler sample pairs, to generate, for each individual pair in at least a subset of said pairs, a periodic pulse synchronized with said frequency source, thereby to define a periodic pulse corresponding to said individual pair and to output each individual pair in said subset, simultaneously with the individual pair's corresponding periodic pulse; andat least one time offset computation unit operative to use said timing units' known positions and at least one sample pair from each of said timing units in order to compute time offset between periodic pulses generated by said two timing units respectively, using a single difference technique. 6. A system according to claim 5 wherein the positions of non-collocated timing units are known at least at decimeter level. 7. A system according to claim 5 wherein said computation unit is operative to determine time offset between corresponding periodic pulses generated by said two timing units respectively by applying a single difference technique to corresponding ones of said pairs, said corresponding ones being defined by at least one time line defined by at least one receiver. 8. A system according to claim 7 wherein each pulse generated by one timing unit and occurring at a first time, is taken by said computation unit to correspond to that pulse from among the pulses generated by another timing unit, whose time of occurrence is closest to said first time. 9. A system according to claim 5 wherein said frequency source is disciplined by an external time source serving as time source for both of said timing units and said nanosecond level accuracy measurement is produced for an unlimited time span. 10. A system according to claim 5 wherein at least one of said timing units is mobile. 11. A system according to claim 5 wherein, in each timing unit, said receiver supplies the frequency source with positioning data which is employed by the frequency source in order to correct frequency drift between said frequency source and said time source. 12. A system according to claim 5 wherein said receiver is operative to generate additional periodic pulses synchronized with the time source and to provide said additional periodic pulses to the frequency source and wherein said frequency source uses said additional pulses in order to correct frequency drift between said frequency source and said time source. 13. A system according to claim 5 wherein each said timing unit includes a memory for storing at least a window of pulses, each pulse being associated with a time tag. 14. A system according to claim 5 and also comprising at least first and second additional devices co-located with respective ones of said timing units wherein said additional devices operate synchronously based on input provided by their co-located timing units. 15. A system according to claim 14 wherein said input comprises at least one of said synchronization signals supplied by the frequency source of its co-located timing unit and at least one periodic pulse generated by the receiver of its co-located timing unit. 16. A system according to claim 15 wherein each said additional device comprises a sensor, the system also comprising a processing unit operative to provide instantaneous and continuous nanosecond-level accuracy measurement of time elapsing between events occurring at said sensor and the sensor of the other additional system, the sensor being operative to receive an event and to perform an evaluation of a time period which has elapsed from receipt of said event back to a most recently generated pulse from among said periodic pulses generated by the timing unit co-located with the sensor, and wherein said evaluation of said time period is performed by counting the number of periods defined by said frequency source, elapsing between reception of said event back to a most recently generated pulse and summing said number with a difference between phases defined by said frequency source at a most recently generated pulse and at said event; wherein said processing unit is operative to compute a sum of said time offset and the difference between said time periods evaluated by said sensors respectively, thereby to measure time which has elapsed between events occurring at the sensors. 17. A system according to claim 16 wherein said events respectively comprise reception of a single external occurrence by said sensors respectively. 18. A system according to claim 16 wherein each of said events comprises an electromagnetic pulse having a rise/fall time which is an order of magnitude less than said accuracy of said measurement of time elapsing between events. 19. A system according to claim 5 wherein said external signal stream defining a time-line is provided to said receiver by said time source. 20. A system according to claim 5 wherein said time offset is determined by employing a common view time transfer procedure. 21. A system according to claim 5 wherein said time source comprises a GNSS time source. 22. A system according to claim 5 wherein said frequency value characterizing the frequency sources comprises a frequency of the frequency sources at a beginning point of said time period. 23. A non-transitory computer usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a method for instantaneous and continuous determination of a relative time offset between non-collocated frequency sources having a relative frequency drift therebetween, said determination being carried out at a required nanosecond level accuracy, the method comprising: computing, and applying to the frequency sources, for disciplining of frequency drift between the frequency sources at a frequency domain, corrections of a relative frequency drift between each frequency source and a single time source, said disciplining being limited by the following condition: the product of a duration of any time period extending between adjacent discrete points of time in a sequence of discrete points of time, times the sum of all frequency corrections effected during said time period divided by a frequency value characterizing the frequency sources, is at least one order of magnitude less than the required accuracy; anddetermining time offset between said non-collocated frequency sources at each discrete point of time in said sequence of discrete points of time.
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이 특허에 인용된 특허 (6)
Allan David W. (Boulder CO) Levine Judah (Boulder CO) Davis Dicky D. (Boulder CO) Weiss Marc A. (Boulder CO), Device and method for providing accurate time and/or frequency.
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