Satellite radio signal receiver, electronic timepiece, date and time acquiring method and recording medium

• US 10,097,385 B2
• Filed: 03/21/2016
• Issued: 10/09/2018
• Est. Priority Date: 06/24/2015
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Abe, Hideo, Matsue, Takeshi
• Primary Examiner(s): Ahn, Sam K
• Assistant Examiner(s): Hassan, Sarah
• Application Number:
  US15/075,677
• Publication Number:
  US 20160380672A1
• Time in Patent Office: 932 Days
• Field of Search: 375260, 370338
• CPC Class Codes: H04L 25/03019 adaptive, i.e. capable of adjustment during data reception
• CPC Class Codes: H04L 25/03292 with channel estimation circuitry
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178

Abstract

A satellite radio signal receiver includes a receiving section which receives radio signals from satellites and demodulates the signals to identify bits of the demodulated signals as received bits; and a processor. The processor compares each received bit of the satellites with estimated bits which are estimated to be received within a possible deviation range from a current date and time acquired as a reception timing of the received bit to obtain comparison result information between the received bits and the estimated bits in relation to deviations within the possible deviation range with respect to each of the satellites, integrates the comparison result information on the received bits of the satellites, specifies a deviation that satisfies a match condition of the received bits and the estimated bits based on the integrated comparison result information, and acquires date and time information based on the deviation that satisfies the match condition.

Claims

1. A satellite radio signal receiver, comprising:

a receiving section which receives radio signals from a plurality of satellites and demodulates the signals to identify bits of the demodulated signals as received bits; and

a processor,

wherein the processor compares each received bit of the plurality of satellites with estimated bits which are estimated to be received within a possible deviation range from a current date and time acquired as a reception timing of the received bit, so as to obtain comparison result information between the received bits and the estimated bits in relation to deviations within the possible deviation range with respect to each of the plurality of satellites,

wherein the processor integrates the comparison result information on the received bits of the plurality of satellites,

wherein the processor specifies a deviation that satisfies a predetermined match condition of the received bits and the estimated bits based on the integrated comparison result information,

wherein the processor acquires date and time information based on date and time indicated by the estimated bits of the deviation that satisfies the predetermined match condition,

wherein the processor specifies a reception timing difference of the received bits which is due to a difference in propagation time between the plurality of satellites,

wherein the processor uses the reception timing difference to align the deviations that are respectively associated with the plurality of satellites in the comparison result information,

wherein the processor integrates the comparison result information of the plurality of satellites by using the respective aligned deviations,

wherein the processor specifies a deviation for at least one of the plurality of satellites, in which the deviation satisfies a predetermined individual match condition of the comparison result information on the received bits of the satellite,

wherein the processor specifies the reception timing difference by using the specified deviation as a reference,

wherein the processor counts comparison numbers and mismatch numbers with respect to the respective deviations and the respective plurality of satellites, in which the comparison numbers are the numbers of comparisons between the received bits and the estimated bits, and the mismatch numbers are the numbers of mismatches in comparisons between the received bits and the estimated bits, and

wherein when the mismatch number relative to the comparison number at a deviation of a satellite is equal to or less than a predetermined upper limit threshold among the comparison numbers and the mismatch numbers with respect to the respective deviations and the respective plurality of satellites, the processor determines that the deviation of the satellite satisfies the individual match condition.

2. The satellite radio signal receiver according to claim 1,

wherein the processor counts comparison numbers and mismatch numbers with respect to the respective deviations and the respective plurality of satellites, in which the comparison numbers are the numbers of comparisons between the received bits and the estimated bits, and the mismatch numbers are the numbers of mismatches in comparisons between the received bits and the estimated bits, and

wherein the processor integrates the comparison result information by calculating total mismatch numbers which are sums of the mismatch numbers of the plurality of satellites with respect to respective aligned deviations and total comparison numbers which are sums of the comparison numbers corresponding respectively to the total mismatch numbers.

3. The satellite radio signal receiver according to claim 1,

wherein every time the receiving section identifies a new received bit, the processor compares the new received bit with estimated bits that are located within the possible deviation range from a reception date and time of the new received bit.

4. The satellite radio signal receiver according to claim 1,

wherein the possible deviation range is determined according to an elapsed time since a last correction of the current date and time counted in a time counting section which counts the acquired current date and time.

5. The satellite radio signal receiver according to claim 1,

wherein the processor generates an estimated bit array which includes the estimated bits within the possible deviation range and identification information which distinguishes the estimated bits from a non-estimated bit in the estimated bit array, and

wherein the processor compares the received bits with the estimated bits based on the identification information.

6. An electronic timepiece, comprising:

the satellite radio signal receiver according to claim 1;

a time counting section which counts the current date and time; and

a timepiece processor which corrects the date and time counted in the time counting section by using the date and time information acquired by the processor.

7. A date and time acquiring method, comprising:

receiving radio signals from a plurality of satellites and demodulating the signals to identify received bits of the demodulated signals as received bits;

comparing each received bit of the plurality of satellites with estimated bits which are estimated to be received within a possible deviation range from a current date and time acquired as a reception timing of the received bit, so as to obtain comparison result information between the received bits and the estimated bits in relation to deviations within the possible deviation range with respect to each of the plurality of satellites;

integrating the comparison result information on the received bits of the plurality of satellites;

specifying a deviation that satisfies a predetermined match condition of the received bits and the estimated bits based on the comparison result information;

acquiring date and time information based on date and time indicated by the estimated bits of the deviation that satisfies the predetermined match condition;

specifying a reception timing difference of the received bits which is due to a difference in propagation time between the plurality of satellites;

using the reception timing difference to align the deviations that are respectively associated with the plurality of satellites in the comparison result information;

integrating the comparison result information of the plurality of satellites by using the respective aligned deviations;

specifying a deviation for at least one of the plurality of satellites, in which the deviation satisfies a predetermined individual match condition of the comparison result information on the received bits of the satellite;

specifying the reception timing difference by using the specified deviation as a reference;

counting comparison numbers and mismatch numbers with respect to the respective deviations and the respective plurality of satellites, in which the comparison numbers are the numbers of comparisons between the received bits and the estimated bits, and the mismatch numbers are the numbers of mismatches in comparisons between the received bits and the estimated bits; and

when the mismatch number relative to the comparison number at a deviation of a satellite is equal to or less than a predetermined upper limit threshold among the comparison numbers and the mismatch numbers with respect to the respective deviations and the respective plurality of satellites, determining that the deviation of the satellite satisfies the individual match condition.

8. A satellite radio signal receiver, comprising:

a receiving section which receives radio signals from a plurality of satellites and demodulates the signals to identify bits of the demodulated signals as received bits; and

a processor,

wherein the processor compares each received bit of the plurality of satellites with estimated bits which are estimated to be received within a possible deviation range from a current date and time acquired as a reception timing of the received bit, so as to obtain comparison result information between the received bits and the estimated bits in relation to deviations within the possible deviation range with respect to each of the plurality of satellites,

wherein the processor integrates the comparison result information on the received bits of the plurality of satellites,

wherein the processor specifies a deviation that satisfies a predetermined match condition of the received bits and the estimated bits based on the integrated comparison result information,

wherein the processor acquires date and time information based on date and time indicated by the estimated bits of the deviation that satisfies the predetermined match condition,

wherein the processor specifies a reception timing difference of the received bits which is due to a difference in propagation time between the plurality of satellites,

wherein the processor uses the reception timing difference to align the deviations that are respectively associated with the plurality of satellites in the comparison result information,

wherein the processor integrates the comparison result information of the plurality of satellites by using the respective aligned deviations,

wherein the processor counts comparison numbers and mismatch numbers with respect to the respective deviations and the respective plurality of satellites, in which the comparison numbers are the numbers of comparisons between the received bits and the estimated bits, and the mismatch numbers are the numbers of mismatches in comparisons between the received bits and the estimated bits, and

wherein the processor integrates the comparison result information by calculating total mismatch numbers which are sums of the mismatch numbers of the plurality of satellites with respect to respective aligned deviations and total comparison numbers which are sums of the comparison numbers corresponding respectively to the total mismatch numbers.

12. The satellite radio signal receiver according to claim 8,

wherein the processor makes a determination as to whether the match condition is satisfied according to whether a predetermined reliability condition of the total mismatch numbers is satisfied.

13. The satellite radio signal receiver according to claim 12,

wherein the processor obtains probabilities of false identification of the received bits based on intensities of the radio signals received by the receiving section,

wherein the processor calculates an integrated probability of false identification from the obtained probabilities of false identification of the respective plurality of satellites, and

wherein the processor determines that the predetermined reliability condition is satisfied when a probability of occurrence of a second lowest mismatch number in a corresponding total comparison number is not within a predetermined validity range that is determined according to the integrated probability of false identification, in which the second lowest mismatch number is a second lowest value in the total mismatch numbers.

14. The satellite radio signal receiver according to claim 13, further comprising:

a storage section which stores a probability table in which reception intensities of a radio signal are associated with probabilities of false identification,

wherein the processor references the probability table based on the intensities of the radio signals to obtain the probabilities of false identification.

15. The satellite radio signal receiver according to claim 13,

wherein the predetermined reliability condition is satisfied at least when a probability of occurrence of a lowest mismatch number in a corresponding total comparison number is within the predetermined validity range that is determined according to the integrated probability of false identification, in which the lowest mismatch number is a lowest value in the total mismatch numbers.

16. The satellite radio signal receiver according to claim 14,

wherein the predetermined reliability condition is satisfied at least when a probability of occurrence of a lowest mismatch number in a corresponding total comparison number is within the predetermined validity range that is determined according to the integrated probability of false identification, in which the lowest mismatch number is a lowest value in the total mismatch numbers.

9. A satellite radio signal receiver, comprising:

a receiving section which receives radio signals from a plurality of satellites and demodulates the signals to identify bits of the demodulated signals as received bits; and

a processor,

wherein the processor compares each received bit of the plurality of satellites with estimated bits which are estimated to be received within a possible deviation range from a current date and time acquired as a reception timing of the received bit, so as to obtain comparison result information between the received bits and the estimated bits in relation to deviations within the possible deviation range with respect to each of the plurality of satellites,

wherein the processor integrates the comparison result information on the received bits of the plurality of satellites,

wherein the processor specifies a deviation that satisfies a predetermined match condition of the received bits and the estimated bits based on the integrated comparison result information,

wherein the processor acquires date and time information based on date and time indicated by the estimated bits of the deviation that satisfies the predetermined match condition,

wherein the processor specifies a reception timing difference of the received bits which is due to a difference in propagation time between the plurality of satellites,

wherein the processor uses the reception timing difference to align the deviations that are respectively associated with the plurality of satellites in the comparison result information,

wherein the processor integrates the comparison result information of the plurality of satellites by using the respective aligned deviations,

wherein the processor specifies a deviation for at least one of the plurality of satellites, in which the deviation satisfies a predetermined individual match condition of the comparison result information on the received bits of the satellite,

wherein the processor specifies the reception timing difference by using the specified deviation as a reference, and

wherein the processor specifies the reception timing difference between the plurality of satellites by obtaining a reference deviation that is a deviation from received bits of one satellite that satisfies the individual match condition and then obtaining a deviation from received bits of each of the other satellite within a phase difference range of a predetermined number of bit from the reference deviation at which received bits match estimated bits to a highest degree.

17. The satellite radio signal receiver according to claim 9,

wherein the plurality of satellites are GPS satellites, and

wherein the relative difference range of the predetermined number of bit has a length of one bit in both sides from the reference deviation.

10. A date and time acquiring method, comprising:

receiving radio signals from a plurality of satellites and demodulating the signals to identify received bits of the demodulated signals as received bits;

comparing each received bit of the plurality of satellites with estimated bits which are estimated to be received within a possible deviation range from a current date and time acquired as a reception timing of the received bit, so as to obtain comparison result information between the received bits and the estimated bits in relation to deviations within the possible deviation range with respect to each of the plurality of satellites;

integrating the comparison result information on the received bits of the plurality of satellites;

specifying a deviation that satisfies a predetermined match condition of the received bits and the estimated bits based on the comparison result information;

acquiring date and time information based on date and time indicated by the estimated bits of the deviation that satisfies the predetermined match condition;

specifying a reception timing difference of the received bits which is due to a difference in propagation time between the plurality of satellites;

using the reception timing difference to align the deviations that are respectively associated with the plurality of satellites in the comparison result information;

integrating the comparison result information of the plurality of satellites by using the respective aligned deviations;

counting comparison numbers and mismatch numbers with respect to the respective deviations and the respective plurality of satellites, in which the comparison numbers are the numbers of comparisons between the received bits and the estimated bits, and the mismatch numbers are the numbers of mismatches in comparisons between the received bits and the estimated bits; and

integrating the comparison result information by calculating total mismatch numbers which are sums of the mismatch numbers of the plurality of satellites with respect to respective aligned deviations and total comparison numbers which are sums of the comparison numbers corresponding respectively to the total mismatch numbers.

11. A date and time acquiring method, comprising:

receiving radio signals from a plurality of satellites and demodulating the signals to identify received bits of the demodulated signals as received bits;

comparing each received bit of the plurality of satellites with estimated bits which are estimated to be received within a possible deviation range from a current date and time acquired as a reception timing of the received bit, so as to obtain comparison result information between the received bits and the estimated bits in relation to deviations within the possible deviation range with respect to each of the plurality of satellites;

integrating the comparison result information on the received bits of the plurality of satellites;

specifying a deviation that satisfies a predetermined match condition of the received bits and the estimated bits based on the comparison result information;

acquiring date and time information based on date and time indicated by the estimated bits of the deviation that satisfies the predetermined match condition;

specifying a reception timing difference of the received bits which is due to a difference in propagation time between the plurality of satellites;

using the reception timing difference to align the deviations that are respectively associated with the plurality of satellites in the comparison result information;

integrating the comparison result information of the plurality of satellites by using the respective aligned deviations;

specifying a deviation for at least one of the plurality of satellites, in which the deviation satisfies a predetermined individual match condition of the comparison result information on the received bits of the satellite;

specifying the reception timing difference by using the specified deviation as a reference; and

specifying the reception timing difference between the plurality of satellites by obtaining a reference deviation that is a deviation from received bits of one satellite that satisfies the individual match condition and then obtaining a deviation from received bits of each of the other satellite within a phase difference range of a predetermined number of bit from the reference deviation at which received bits match estimated bits to a highest degree.