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US5587716A
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Gap coverage for GPS signals
Assignee: Trimble Inc
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Filing: 1995-09-29
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Granted: 1996-12-24
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Expires: 2015-09-29
Abstract
Abstract A method for compensating for temporary loss of differential GPS correction signals for a satellite, numbered j, during an IODE changeover interval. Differences Δe i (t;j;n+1,n)=e i (t;j;n+1)-e i (t;j;n) (i=1, . . . , I) are formed for I ephemeris parameters used to describe the ephemeris for the satellite (j) during IODE intervals number n+1 and n. These differences are approximated for a DGPS blank-out time interval, given by t(j;n+1) IODE Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, during which a GPS reference station continues to broadcast DGPS correction information based on the old ephemeris data that was valid during the preceding IODE time interval, given by t(j;n) IODE ≦t<t(j;n+1) IODE . These ephemeris differences are used by a mobile station that receives DGPS correction information from the GPS reference station to produce corrected GPS information for a blank-out time interval. Ephemeris parameter differences can be replaced by differences of satellite-station ranges ΔR(t;j;n+1,n)=R(t;j;n+1)-R(t;j;n) in an alternative approach.
Inventors
- 👤 Len Sheynblat
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:38
CPC Classifications
G; G01; G01S; G01S19/00; G01S19/01; G01S19/13; G01S19/24; G01S19/27; G01S19/38; G01S19/39; G01S19/40; G01S19/41; G01S5/00; G01S5/0009; G01S5/009
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
408 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of each of I ephemeris parameters e i (t;j;n) (i=1, . . . , I; I≧1) that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of each of I ephemeris parameters e i (t;j;n+1) (i=1, . . . , I; I≧1) that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining an approximation Δπ i (t;j;n+1,n) for each of the I ephemeris parameter difference values Δe i (t;j;n+1,n)=e i (t;j;n+1)-e i (t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; and estimating the values of each of the I ephemeris parameters e i (t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation e i (t;j;n) est =e i (t;j;n+1)-Δπ i (t;j;n+1,n).
Claim 2
Independent Claim
408 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of each of I ephemeris parameters e i (t;j;n) (i=1, . . . , I; I≧1) that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of each of I ephemeris parameters e i (t;j;n+1) (i=1, . . . , I; I≧1) that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining an approximation Δπ i (t;j;n+1,n) for each of the I ephemeris parameter difference values Δe i (t;j;n+1,n)=e i (t;j;n+1)-e i (t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; and estimating the values of each of the I ephemeris parameters e i (t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation e i (t;j;n) est =e i (t;j;n+1)-Δπ i (t;j;n+1,n).
Claim 3
Dependent Claim
46 words
The method of claim 1, further comprising the step of choosing said approximation π i (t;j;n+1,n) for said ephemeris parameter difference Δe i (t;j;n+1,n) from the class of functions consisting of polynomials, ratios of polynomials, trigonometric functions, sums and ratios of exponential functions, and logarithm functions.
Claim 4
Dependent Claim
28 words
The method of claim 2, further comprising the step of choosing said approximation π i (t;j;n+1,n) to be a polynomial of degree M≧2 in the time variable t.
Claim 5
Dependent Claim
31 words
The method of claim 1, further comprising the step of choosing said second temporal length Δt rev ,ref to be not less than 18 seconds and not more than 600 seconds.
Claim 6
Dependent Claim
31 words
The method of claim 1, further comprising the step of choosing said third temporal length Δt rev ,mob to be not less than 18 seconds and not more than 600 seconds.
Claim 7
Independent Claim
378 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of the range R(t;j;n) from satellite j to a selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of the range R(t;j;n+1) from satellite j to the selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining an approximation Δρ(t;j;n+1,n) for the range difference values ΔR(t;j;n+1,n)=R(t;j;n+1)-R(t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; and estimating the range values R(t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation R(t;j;n) est =R(t;j;n+1)-Δρ(t;j;n+1,n).
Claim 8
Independent Claim
378 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of the range R(t;j;n) from satellite j to a selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of the range R(t;j;n+1) from satellite j to the selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining an approximation Δρ(t;j;n+1,n) for the range difference values ΔR(t;j;n+1,n)=R(t;j;n+1)-R(t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; and estimating the range values R(t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation R(t;j;n) est =R(t;j;n+1)-Δρ(t;j;n+1,n).
Claim 9
Dependent Claim
41 words
The method of claim 6, further comprising the step of choosing said approximation Δρ(t;j;n+1,n) for said range difference ΔR(t;j;n+1,n) from the class of functions consisting of polynomials, ratios of polynomials, trigonometric functions, sums and ratios of exponential functions, and logarithm functions.
Claim 10
Dependent Claim
26 words
The method of claim 7, further comprising the step of choosing said approximation Δρ(t;j;n+1,n) to be a polynomial of degree M≧1 in the time variable t.
Claim 11
Dependent Claim
31 words
The method of claim 6, further comprising the step of choosing said second temporal length Δt rev ,ref to be not less than 18 seconds and not more than 600 seconds.
Claim 12
Dependent Claim
31 words
The method of claim 6, further comprising the step of choosing said third temporal length Δt rev ,mob to be not less than 18 seconds and not more than 600 seconds.
Claim 13
Independent Claim
401 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of each of I ephemeris parameters e i (t;j;n) (i=1, . . . , I; I≧1) that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of each of I ephemeris parameters e i (t;j;n+1) (i=1, . . . , I; I≧1) that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining an approximation π i (t;j;n) for each of the I ephemeris parameter values e i (t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref ; and estimating the values of each of the I ephemeris parameters e i (t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation e i (t;j;n) est =π i (t;j;n).
Claim 14
Independent Claim
401 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of each of I ephemeris parameters e i (t;j;n) (i=1, . . . , I; I≧1) that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of each of I ephemeris parameters e i (t;j;n+1) (i=1, . . . , I; I≧1) that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining an approximation π i (t;j;n) for each of the I ephemeris parameter values e i (t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref ; and estimating the values of each of the I ephemeris parameters e i (t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation e i (t;j;n) est =π i (t;j;n).
Claim 15
Independent Claim
377 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of the range R(t;j;n) from satellite j to a selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of the range R(t;j;n+1) from satellite j to the selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining an approximation ρ(t;j;n) for the range values R(t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; and estimating the range values R(t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation R(t;j;n) est =ρ(t;j;n).
Claim 16
Independent Claim
377 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of the range R(t;j;n) from satellite j to a selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of the range R(t;j;n+1) from satellite j to the selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining an approximation ρ(t;j;n) for the range values R(t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; and estimating the range values R(t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation R(t;j;n) est =ρ(t;j;n).
Claim 17
Independent Claim
416 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of the range R(t;j;n) from satellite j to a selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of the range R(t;j;n+1) from satellite j to the selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining a first approximation ρ'(t;j;n+1) for the range values R(t;j;n+1) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; determining a second approximation Δρ"(t;j;n+1,n) for the range difference values ΔR(t;j;n+1,n)=R(t;j;n+1)-R(t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; and estimating the range values R(t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation R(t;j;n) est =ρ'(t;j;n+1)-Δρ"(t;j;n+1,n).
Claim 18
Independent Claim
416 words
A method for compensating for temporary loss of differential GPS correction signals for a satellite during an IODE changeover interval, the method comprising the steps of: receiving ephemeris data for a satellite, numbered j, during two consecutive IODE time intervals, given by t(j;n) IODE ≦t<t(j;n+1) IODE , and t(j;n+1) IODE ≦t<t(j;n+2) IODE , when the ephemeris data are available for at least one satellite numbered j=1, . . . , J (J≧3); receiving differential GPS correction signals for satellite number j for a time interval t(j;n) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the IODE time interval t(j;n) IODE ≦t<t(j;n+1) IODE for satellite j, where Δt ch is a first selected non-negative temporal length, Δt rev ,ref is a second selected positive temporal length; receiving differential GPS correction signals for satellite j for a time interval t(j;n+1) IODE +Δt ch +Δt rev ,ref ≦t<t(j;n+2) IODE +Δt ch +Δt rev ,ref, based upon ephemeris data that are applicable for the time interval t(j;n+1) IODE ≦t<t(j;n+2) IODE for satellite j; for two selected times t=t' 2 and t=t' 3 satisfying the constraints t(j;n) IODE <t' 2 ≦t(j;n+1) IODE <t' 3 , determining the time variation of the range R(t;j;n) from satellite j to a selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t' 2 ≦t<t' 3 ; for two selected times t=t" 2 and t=t" 3 satisfying the constraints t(j;n+1) IODE +Δt rev ,mob ≦t" 2 <t" 3 , determining the time variation of the range R(t;j;n+1) from satellite j to the selected location from ephemeris data that determine the ephemeris of satellite j during the time interval given by t" 2 ≦t<t" 3 , where Δt rev ,mob is a third selected positive temporal length; determining a first approximation ρ'(t;j;n+1) for the range values R(t;j;n+1) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; determining a second approximation Δρ"(t;j;n+1,n) for the range difference values ΔR(t;j;n+1,n)=R(t;j;n+1)-R(t;j;n) in a time interval that includes at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref ; and estimating the range values R(t;j;n) in at least a portion of the time interval t(j;n+1) IODE +Δt rev ,mob ≦t<t(j;n+1) IODE +Δt ch +Δt rev ,ref by the approximation R(t;j;n) est =ρ'(t;j;n+1)-Δρ"(t;j;n+1,n).
References Cited (Backward Citations)
US5398034A
Cited
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