WO2013140909A1 - Signal search method, signal search program, signal search device, global navigation satellite system (gnss) signal receiver, and information terminal - Google Patents

Signal search method, signal search program, signal search device, global navigation satellite system (gnss) signal receiver, and information terminal Download PDF

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Publication number
WO2013140909A1
WO2013140909A1 PCT/JP2013/053888 JP2013053888W WO2013140909A1 WO 2013140909 A1 WO2013140909 A1 WO 2013140909A1 JP 2013053888 W JP2013053888 W JP 2013053888W WO 2013140909 A1 WO2013140909 A1 WO 2013140909A1
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frequency
signal
search
integration time
target
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PCT/JP2013/053888
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French (fr)
Japanese (ja)
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明弘 大杉
盾 王
一登 多田
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古野電気株式会社
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related

Definitions

  • the present invention relates to a signal search method for searching for a desired signal from a received signal, and more particularly to a method for searching for a GPS signal in GNSS.
  • GPS Global Positioning System
  • GNSS Global Navigation Satellite System
  • GPS GPS signals transmitted from a plurality of GPS satellites are received, and the receiver performs positioning using the code phase and carrier phase of the received GPS signals.
  • a different spreading code is set for each GPS satellite, and each GPS signal is code-modulated with a different spreading code.
  • a GPS signal from a GPS satellite different from the target GPS satellite may be erroneously captured as the target GPS signal and tracking processing may be performed.
  • Such a phenomenon is called cross-correlation.
  • Patent Document 1 uses the following method. First, a strong signal is detected from the result of calculating the integrated correlation value at a predetermined frequency interval and at a fixed integration time. Cross-correlation is detected by utilizing the fact that the difference between the frequency of the detected strong signal and the frequency to be captured has a predetermined relationship with the signal level. If the detected strong signal is determined to be cross-correlation, the signal search is continued.
  • the integration time for each code phase and frequency is constant until the search range, that is, the entire code phase range and frequency range for performing signal search can be searched. Then, after completing the entire search at least once (in some cases, a plurality of times), if the target signal cannot be detected, the signal search is executed by extending the integration time.
  • the integration time is set longer than the integration time for strong signal detection.
  • the integrated correlation value is calculated with the same integration time over the entire search range as described above, for example, even if the integration time is set short, a weak signal or the like cannot be detected. The entire range must be searched repeatedly, resulting in a longer integration time. On the other hand, if the integration time is set longer, the integration time at each integration correlation value calculation point in the two-dimensional range of code phase and frequency becomes longer, and the search time for the entire search range becomes longer.
  • an object of the present invention is to provide a signal search method capable of capturing a target signal more accurately by reducing the possibility of erroneous detection due to cross-correlation in a shorter search time than the conventional method.
  • the present invention is a signal search method for capturing a target signal, and includes an integration time determination step, a correlation value calculation step, and an integration correlation value calculation step.
  • the integration time determination step the integration time at the search target frequency is set according to the frequency difference between the frequency of the signal being tracked and the search target frequency.
  • the correlation value calculating step calculates a correlation value between the replica signal of the target signal and the received signal.
  • the integrated correlation value calculating step the integrated correlation value is calculated by integrating the correlation value with the integrated time set in the integrated time determining step.
  • the integration time of the correlation value at the frequency currently being searched is determined by the difference between the frequency of the signal being tracked and the frequency currently being searched. That is, the integration time can be changed by the difference between the frequency of the signal being tracked and the frequency currently being searched. Thereby, the influence on the integrated correlation value by the signal being tracked can be reduced. Furthermore, by setting the integration time appropriately, it is possible to shorten the total integration time over the entire frequency band, compared to simply making the integration time constant.
  • the integration time determining step of the signal search method of the present invention includes a frequency interval determining step, a segment determining step, and a determining step.
  • the frequency section determining step a plurality of frequency sections to which the search target frequency can selectively correspond are determined based on the difference from the search target frequency based on the frequency of the signal being tracked.
  • the classification determination step it is determined to which of a plurality of frequency sections the frequency to be searched belongs.
  • the integration time is set for each frequency section.
  • the search target frequency is divided into a plurality of frequency sections, and the integration time is determined for each frequency section.
  • the integration time determination process can be simplified and shortened without significantly reducing the signal search performance.
  • the frequency interval determination step of the signal search method of the present invention includes a step of setting a plurality of frequency intervals based on the repetition interval of the frequency that becomes the correlation peak that appears when the integrated correlation value is calculated by the signal being tracked.
  • the classification determination step includes a step of calculating a frequency difference value between the frequency to be searched and the frequency of the signal being tracked, and a step of determining in which range of the plurality of frequency sections the frequency difference value is. Have.
  • This method specifically shows a search method in the case where the frequency of the correlation peak that appears when the integrated correlation value is calculated by the signal being tracked is repeated at predetermined intervals, that is, when cross-correlation occurs.
  • the change in the correlation value between the frequencies of the correlation peaks is the same, if a frequency section between the frequencies of one set of correlation peaks is set, the correlation between the frequencies of other correlation peaks is also
  • the present invention can be similarly applied, and the setting of the frequency section for the entire frequency band can be simplified and shortened without degrading the signal search performance.
  • the possibility of the presence or absence of a search target signal in each frequency section can be understood to some extent from the preliminary search result. Accordingly, it is possible to optimize the integration time based on the use of the preliminary search result, that is, based on the possibility of presence or absence of a search target signal.
  • the step of detecting the signal strength of the preliminary detection signal and the number of signal strengths of the preliminary detection signal belonging to each of a plurality of preset signal strength categories are detected. And a step of further correcting the integration time in accordance with the distribution of the number of preliminary detection signals belonging to each signal intensity category.
  • the integration time can be further optimized by using the signal intensity of the preliminary detection signal detected from the preliminary search result.
  • the signal search method of the present invention includes a step of setting a plurality of search target frequencies at the same interval as the repetition interval. Then, the correlation value calculating step is executed in parallel at a plurality of search target frequencies.
  • a plurality of search target frequencies are regarded as one group, and an integrated correlation value can be calculated simultaneously for each search target frequency in the group.
  • the signal search process can be further shortened.
  • the target signal is a GPS signal broadcast for each GPS satellite.
  • This method specifically indicates that the target signal (search target signal) is a GPS signal. That is, it shows that the influence of cross-correlation in capturing the GPS signal is reduced, and the GPS signal is captured more reliably.
  • the target GPS signal can be captured in a shorter search time than the conventional method, and the target signal can be accurately captured with almost no erroneous detection due to cross-correlation.
  • FIG. 3 is a flowchart of a signal search method according to an embodiment of the present invention. It is a figure which shows the correlation characteristic of the cross correlation by the change of integration time. It is a figure for demonstrating the setting concept of a frequency area. It is a figure which shows an example of the map for integration time setting. It is a flowchart of the formation process of the lamination time change map. It is a figure for demonstrating the code phase and frequency setting concept for performing the correlation processing method in the search process of this embodiment. It is a flowchart which shows the determination process of a frequency area, and the setting process of integration time. It is a figure for demonstrating the determination concept of a frequency area, and the setting concept of integration time.
  • FIG. 1 It is a figure for demonstrating the setting concept of a signal strength division. It is a figure which shows an example of the map for integration time setting also including a signal strength division. It is a block diagram which shows the structure of the GPS signal receiver 1 which concerns on embodiment of this invention. It is a block diagram which shows the structure of the information equipment terminal 100 provided with the GPS signal receiver 1. FIG.
  • a signal search method will be described with reference to the drawings.
  • a method for searching for a GPS signal transmitted from a GPS satellite will be described.
  • a case will be described where there is one tracking GPS signal at the start of the signal search shown in this embodiment.
  • FIG. 1 is a flowchart of the signal search method of this embodiment.
  • the signal search method of this embodiment first obtains the frequency F B of the GPS signal in the tracking (S101).
  • the GPS signal being tracked is a signal that can cause cross-correlation at the time of signal search shown in the present embodiment.
  • FIG. 2 is a diagram illustrating a correlation characteristic of cross correlation due to a change in integration time.
  • the accumulated time for obtaining the characteristics shown in FIGS. 2C and 2D is longer than the accumulated time for obtaining the characteristics shown in FIGS. 2A and 2B (about twice).
  • the integration time for obtaining the characteristics shown in (F) is longer (further about twice) than the integration time for obtaining the characteristics shown in FIGS. 2B is an enlarged view in the frequency direction of FIG. 2A
  • FIG. 2D is an enlarged view in the frequency direction of FIG. 2C
  • FIG. 2F is an enlarged view of FIG. FIG.
  • the peak frequency at which the integrated correlation value becomes maximum appears at intervals of 1000 Hz, and the integrated correlation value decreases as the distance from the peak frequency increases. Then, the integrated correlation value is minimized at a frequency 500 Hz away from the peak frequency, in other words, at an intermediate frequency between adjacent peak frequencies.
  • the cross correlation correlation characteristics are the same on the high frequency side and the low frequency side with reference to the peak frequency. In other words, the correlation characteristics of cross correlation are the same characteristics on the high frequency side and the low frequency side with respect to the frequency at which the integrated correlation value is minimized.
  • FIG. 3 is a diagram for explaining the concept of setting frequency intervals.
  • the frequency of the GPS signal being tracked (the signal causing the cross correlation) is set as a reference frequency (0 Hz), and is separated from the reference frequency by 500 Hz.
  • the frequency range is set by being divided into a first frequency interval ARc, a second frequency interval ARn, and a third frequency interval ARf.
  • the first frequency section ARc is conceptually a frequency section that is most susceptible to cross-correlation and is very close to the cross-correlation frequency.
  • the first frequency section ARc is set in the frequency band from the reference frequency to the first threshold frequency Fc.
  • the second frequency section ARn conceptually has a certain degree of possibility of being affected by cross-correlation, and is a frequency section that is separated from the close proximity section to the cross-correlation frequency but is close to a certain degree.
  • the second frequency interval ARn is set in a frequency band from the first threshold frequency Fc to the second threshold frequency Fn ( ⁇ Fc).
  • the third frequency section ARf is conceptually a frequency section that is hardly affected by the cross-correlation and is separated from the cross-correlation frequency.
  • the third frequency section ARf is set in a frequency band from the second threshold frequency Fn to 500 Hz.
  • the first threshold frequency Fc and the second threshold frequency Fn are set as appropriate based on the integration time.
  • the first threshold frequency Fc is set so that the frequency band substantially corresponding to the main lobe of cross correlation becomes the first frequency section ARc.
  • the second threshold frequency Fn is set so that the frequency band substantially corresponding to the side lobe adjacent to the main lobe becomes the second frequency section ARn.
  • the first threshold frequency Fc and the second threshold frequency Fn are changed according to the change of the correlation characteristics. Just do it. For example, as the integration time becomes longer, the width of the main lobe and the side lobe becomes narrower, so the first threshold frequency Fc and the second threshold frequency Fn may be set to smaller values.
  • FIG. 4 is a diagram showing an example of the integrated time setting map.
  • FIG. 5 is a flowchart of the process for forming the stacking time changing map.
  • the frequency difference value Df (F) of the preliminary detection signal is obtained from the following equation.
  • Df (F) (ABS (F ⁇ F B )) / 1000 [Hz]
  • ABS () is a symbol representing absolute value calculation.
  • the normalized frequency difference value ⁇ f (F) of the preliminary detection signal is obtained from the following equation.
  • the normalized frequency difference value ⁇ f (F) of each preliminary detection signal calculated in this way is compared with the first threshold frequency Fc and the second threshold frequency Fn (S302).
  • the preliminary detection signal is determined to be within the first frequency interval ARc (S305), and the first frequency The number of preliminary detection signals in the section ARc is incremented by 1 (S306).
  • the preliminary detection signal is the second threshold frequency Fn. It is determined that it is within the frequency interval ARn (S307), and the number of preliminary detection signals in the second frequency interval ARn is incremented by 1 (S308).
  • the preliminary detection signal is the third threshold frequency Fn. It is determined that it is within the frequency interval ARf (S309), and the number of preliminary detection signals in the third frequency interval ARf is counted by +1 (S310).
  • Step S302 Processing for determining which frequency section the preliminary detection signal corresponds to is performed for all the preliminary detection signals (S311: Yes), and when there is a preliminary detection signal for which the determination processing is not performed ( S311: No), the above-described processing from step S302 is repeated until determination processing for all the preliminary detection signals is completed.
  • a map (see FIG. 4) of the number of preliminary detection signals existing for each of the first frequency section ARc, the second frequency section ARn, and the third frequency section ARf is formed.
  • the integration time Tc of the first frequency interval ARc, the integration time Tn of the second frequency interval ARn, and the integration time Tf of the third frequency interval ARf are set.
  • the integration time Tc of the first frequency interval ARc and the integration time Tn of the second frequency interval ARn is set so as to satisfy the relationship of Tc> Tn> Tf.
  • the integration time is set longer for frequency sections that are more susceptible to cross-correlation.
  • the peak of the correlation characteristic due to cross-correlation becomes steeper as the integration time becomes longer. For this reason, the longer the integration time, the higher the resolution of signal detection on the frequency axis.
  • each frequency section Accordingly, the influence of cross-correlation is appropriately reduced, and the target GPS signal can be detected and captured more accurately.
  • FIG. 6 is a diagram for explaining the concept of setting the code phase and frequency for performing the correlation processing method in the search processing of this embodiment.
  • the correlation process is simultaneously performed at 2046 points having an interval of 0.5 [chip] with respect to the C / A code of 1023 [chip].
  • Run to calculate the integrated correlation value That is, when the search frequency F sig is set, the integrated correlation value is calculated in parallel at 2046 points at the search frequency F sig .
  • the preceding code phase range can be correlated simultaneously.
  • the search frequency is calculated by calculating the integrated correlation value by executing the correlation process in parallel with 8 points set at 1000 Hz intervals as one group.
  • search frequencies F sig 011, F sig 012, F sig 013, F sig 014, F sig 015, F sig 016, F sig 017, F sig are shown in FIG.
  • group Gr1 of 018 correlation processing is executed simultaneously.
  • the correlation processing is simultaneously performed at 8 points.
  • the correlation processing is simultaneously executed at 8 points.
  • Such correlation processing is sequentially executed from the group Gr1 to the group Gr19, thereby obtaining an integrated correlation value for one channel covering the entire search frequency.
  • the correlation processing from the group Gr1 is sequentially executed again.
  • the correlation process for one channel (calculation of the laminated correlation value) can be shortened as compared with the sequential execution individually.
  • the search frequencies F sig included in the same group Gr correspond to the same frequency section. Therefore, it is not necessary to individually perform a process of determining a frequency section (a process of determining the integration time) for all search frequencies included in the group Gr, and it is sufficient to perform the process with one representative search frequency F sig .
  • the determination of the frequency interval is performed for all of the search frequencies F sig 011, F sig 012, F sig 013, F sig 014, F sig 015, F sig 016, F sig 017, and F sig 018.
  • the frequency interval is determined by the search frequency F sig 011 to determine the integration time, and the other search frequencies F sig 012, F sig 013, F sig 014, F sig 015, F sig 016, F sig 016
  • a frequency interval (integrated time) of the search frequency F sig 011 may be applied to 017, F sig 018.
  • FIG. 7 is a flowchart showing a frequency interval determination process and an integration time setting process.
  • the frequency difference value Df is obtained from the following equation.
  • Df (ABS (F sig ⁇ F B )) / 1000 [Hz]
  • the frequency difference value is normalized so as to be a value between 0 Hz and 500 Hz, and a normalized frequency difference value ⁇ f sig is calculated.
  • the standardized frequency difference value ⁇ f sig for the search frequency F sig calculated in this way is compared with the first threshold frequency Fc described above (S402).
  • the search frequency F sig is determined to be within the first frequency interval ARc, and the integration time Tc is adopted for the search frequency F sig . (S404).
  • the normalized frequency difference value ⁇ f sig is equal to or higher than the first threshold frequency Fc (S402: No)
  • the normalized frequency difference value ⁇ f sig with respect to the search frequency F sig is compared with the above-described second threshold frequency Fn (S403). ).
  • the search frequency F sig is determined to be within the second frequency interval ARn, and the integration time Tn is adopted for the search frequency F sig . (S405).
  • the search frequency F sig is determined to be within the third frequency interval ARf, and the integration time Tf is adopted for the search frequency F sig . (S406).
  • F sig 051, F sig 061, F sig 071, F sig 081, F sig 091, F sig 101, F sig 111, F sig 121, F sig 131, F sig 141, F sig 151, F sig 161, F sig 171, F sig 181 and F sig 191 are set as shown in FIG. 8.
  • FIG. 8 is a diagram for explaining the determination concept of the frequency section and the setting concept of the integration time.
  • FIG. 8 shows an example in which the search frequency F sig 011 of each group Gr1 is farthest from the peak frequency of cross correlation .
  • the search frequencies F sig 011, F sig 021, F sig 031, F sig 041, F sig 051, and F sig 061 correspond to the third frequency interval ARf.
  • the search frequencies F sig 071 and F sig 081 correspond to the second frequency interval ARn.
  • the search frequencies F sig 091, F sig 101, and F sig 111 correspond to the first frequency interval ARc.
  • the search frequencies F sig 121 and F sig 131 correspond to the second frequency interval ARn.
  • the search frequencies F sig 141, F sig 151, F sig 161, F sig 171, F sig 181, and F sig 191 correspond to the third frequency interval ARf.
  • the search frequencies F sig 011, F sig 021, F sig 031, F sig 041, F sig 051, F sig 061, and the search frequencies F sig 141, F sig 151, F sig 161, F sig 171, F sig 181 , F sig 191 employs the integration time Tf.
  • the integration time Tn is adopted.
  • the integration time Tc is adopted.
  • Correlation processing is performed at each search frequency according to the integration time set in this way, and an integration correlation value corresponding to the integration time is calculated.
  • the process of setting the integration time and outputting the integration correlation value is continuously executed until the entire frequency band is covered (S107: No ⁇ S105).
  • a GPS signal is captured based on the integrated correlation value in each code phase and frequency (S108).
  • a code phase and frequency whose integrated correlation value is greater than or equal to a predetermined threshold are detected, and this timing is used as a GPS signal capture timing.
  • the threshold value may be corrected for each frequency section. Further, the integrated correlation value may be corrected for each frequency section.
  • the integration times Tn and Tf of the second and third frequency sections ARn and ARf that are not easily affected by cross-correlation are made shorter than the integration time Tc of the first frequency section that is easily affected by cross-correlation.
  • the signal search time for one channel can be shortened compared with the case where the integration time Tc of the first frequency section that is easily affected by cross-correlation is employed.
  • GPS signals can be captured in a shorter time than the conventional method without causing erroneous capture due to cross-correlation.
  • the integration times Tc, Tn, and Tf are set according to the number of counts.
  • the integration time may be lengthened. If such integration time is set, a preliminary search is not required.
  • the integration time Tn of the second frequency section ARn and the integration time Tf of the third frequency section ARf are equally shortened when there is no preliminary detection signal, Settings such as uniformly shortening each accumulated time are possible, and a more optimal accumulated time can be set according to the situation.
  • FIG. 9 is a diagram for explaining the concept of setting signal strength categories.
  • FIG. 10 is a diagram showing an example of an integration time setting map including a signal intensity category.
  • the signal intensity classification is set in three stages according to the C / No of the preliminary detection signal. Specifically, the first threshold value C / N0n is set to the first signal strength section ZONEw, the first threshold value C / N0n to the second threshold value C / N0s is set to the second signal strength section ZONEw, The threshold value C / N0s or more is set in the third signal strength category ZONEs.
  • an integrated time setting map as shown in FIG. 10 can be formed together with the determination result of the frequency section described above.
  • the accumulated time of each frequency section is set with reference to the distribution of the number of preliminary detection signals corresponding to each signal intensity category. For example, as shown in FIG. 10, if it is determined that a preliminary detection signal having a high C / N0 exists in the first frequency interval ARc, the preliminary detection signal is a GPS signal being tracked that generates a peak frequency due to cross-correlation. Therefore, the accumulated time may be corrected to be longer so that it is less affected by the GPS signal being tracked.
  • FIG. 11 is a block diagram showing a configuration of the GPS signal receiving apparatus 1 according to the embodiment of the present invention.
  • the GPS signal receiving device 1 includes a GPS receiving antenna 10, an RF processing unit 20, a baseband processing unit 30, and a positioning calculation unit 40.
  • the GPS receiving antenna 10 receives a GPS signal broadcast (transmitted) from each GPS satellite and outputs it to the RF processing unit 20.
  • the RF processing unit 20 down-converts the received GPS signal, generates an intermediate frequency signal (IF signal), and outputs it to the baseband processing unit 30.
  • the baseband processing unit 30 corresponds to a “signal search device” including the “integrated time determining unit” and the “correlation value calculating unit” of the present invention.
  • the baseband processing unit 30 also corresponds to the “capture tracking unit” of the present invention.
  • the baseband processing unit 30 may individually implement hardware corresponding to the “integration time determination unit” and hardware corresponding to the “correlation value calculation unit” and the “capture tracking unit”. You may implement
  • the baseband processing unit 30 generates a baseband signal by multiplying the IF signal by the carrier frequency signal, and performs a GPS signal capturing process and a tracking process using the baseband signal. At this time, the signal search method described above is used for the acquisition process. Thereby, the erroneous capture of cross-correlation can be suppressed and the target GPS signal can be reliably captured.
  • the capturing process for such a captured GPS signal shifts to a tracking process.
  • the code correlation result and carrier correlation result obtained by the tracking, and the pseudo distance obtained from the code correlation result are output to the positioning calculation unit 40.
  • the positioning calculation unit 40 demodulates the navigation message based on the code correlation result, and performs positioning of the GPS signal receiving device 1 from the code correlation result, the carrier phase result, and the pseudorange.
  • the baseband processing unit 30 that executes the above-described signal search method may be realized by a hardware group that executes each process, and stores each process of the above-described signal search method in a storage medium in a programmed state. In addition, it may be realized by a mode in which the computer reads and executes the program.
  • FIG. 12 is a block diagram illustrating a main configuration of the information equipment terminal 100 including the GPS signal receiving device 1 of the present embodiment.
  • An information equipment terminal 100 as shown in FIG. 12 is, for example, a mobile phone, a car navigation device, a PND, a camera, a clock, and the like, and includes an antenna 10, an RF processing unit 20, a baseband processing unit 30, a positioning calculation unit 40, and application processing. Part 130 is provided.
  • the antenna 10, the RF processing unit 20, the baseband processing unit 30, and the positioning calculation unit 40 have the above-described configuration, and the GPS signal receiving device 1 is configured as described above.
  • the application processing unit 130 displays the own device position and the own device speed based on the positioning result output from the GPS signal receiving device 1, and executes processing for use in navigation and the like.
  • the present invention can be similarly applied to capturing other GNSS signals. Furthermore, the present invention can be similarly applied to capturing a wireless communication signal in which a peak appears in a correlation value at a predetermined frequency interval.
  • frequency section setting process an example in which three frequency sections are set is shown. However, two or more frequency sections can be set. Similarly, the signal strength section can be set to two or more signal strength sections.
  • the integration time can be corrected by setting or changing either one or both of the coherent integration time and the non-coherent integration time. Good.
  • the search target frequency F sig is divided into a plurality of frequency sections, and the integration time is set for each frequency section.
  • the search target frequency F sig and the frequency F B of the GPS signal being tracked are shown. It is also possible to set the integration time for each search target frequency F sig according to the frequency difference value. In this case, for example, the frequency F B and the frequency difference value is larger in the GPS signal in the tracking and search target frequency F sig, it may be set to be shorter integration time.
  • GPS signal receiving device 10: GPS receiving antenna
  • 20 RF processing unit
  • 30 baseband processing unit
  • 40 positioning calculation unit
  • 100 information equipment terminal
  • 130 application processing unit

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  • Radar, Positioning & Navigation (AREA)
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Abstract

[Problem] To more accurately capture target Global Positioning System (GPS) signals in a shorter search time than with methods of the prior art. [Solution] The frequency (FB) of a GPS signal is acquired during tracking (S101). Frequency intervals for integration time changes are established from the frequency (FB) (S102). Detection results for signals detected in a preliminary search are used to determine the integration time for each frequency interval (S103, S104). A determination is made as to whether a search frequency (Fsig) pertains to any of the frequency intervals, the integration time is determined for each search frequency (Fsig), and an integration correlation value is calculated (S105).

Description

信号サーチ方法、信号サーチプログラム、信号サーチ装置、ＧＮＳＳ信号受信装置、および情報機器端末Signal search method, signal search program, signal search device, GNSS signal reception device, and information equipment terminal
　この発明は、受信信号から所望信号をサーチする信号サーチ方法、特に、ＧＮＳＳにおけるＧＰＳ信号をサーチする方法に関する。 The present invention relates to a signal search method for searching for a desired signal from a received signal, and more particularly to a method for searching for a GPS signal in GNSS.
　現在、ＧＮＳＳ（Ｇｌｏｂａｌ　Ｎａｖｉｇａｔｉｏｎ　Ｓａｔｅｌｌｉｔｅ　Ｓｙｓｔｅｍ）の一つとして、ＧＰＳ（Ｇｌｏｂａｌ　Ｐｏｓｉｔｉｏｎｉｎｇ　Ｓｙｓｔｅｍ）がある。 Currently, there is GPS (Global Positioning System) as one of GNSS (Global Navigation Satellite System).
　ＧＰＳでは、複数のＧＰＳ衛星から送信されるＧＰＳ信号を受信し、受信したＧＰＳ信号のコード位相やキャリア位相を用いて、受信機の測位を行う。ＧＰＳでは、ＧＰＳ衛星毎に異なる拡散コードが設定されており、各ＧＰＳ信号は、異なる拡散コードでコード変調されている。 In GPS, GPS signals transmitted from a plurality of GPS satellites are received, and the receiver performs positioning using the code phase and carrier phase of the received GPS signals. In GPS, a different spreading code is set for each GPS satellite, and each GPS signal is code-modulated with a different spreading code.
　このようなＧＰＳでは、目的とするＧＰＳ衛星とは異なるＧＰＳ衛星からのＧＰＳ信号を、目的とするＧＰＳ信号と誤って捕捉し、追尾処理を行ってしまうことがある。このような現象はクロスコリレーションと呼ばれている。 In such a GPS, a GPS signal from a GPS satellite different from the target GPS satellite may be erroneously captured as the target GPS signal and tracking processing may be performed. Such a phenomenon is called cross-correlation.
　クロスコリレーションを防ぐ方法として、特許文献１では、次の方法を用いている。まず、所定周波数間隔で且つ一定の積算時間で積算相関値を算出した結果から強信号を検出する。検出した強信号の周波数と捕捉対象の周波数との差と、信号レベルとが所定の関係があることを利用して、クロスコリレーションの検出を行っている。そして、検出した強信号がクロスコリレーションと判定されれば、信号サーチを継続する。 As a method for preventing cross-correlation, Patent Document 1 uses the following method. First, a strong signal is detected from the result of calculating the integrated correlation value at a predetermined frequency interval and at a fixed integration time. Cross-correlation is detected by utilizing the fact that the difference between the frequency of the detected strong signal and the frequency to be captured has a predetermined relationship with the signal level. If the detected strong signal is determined to be cross-correlation, the signal search is continued.
　上述のように、従来の信号サーチ方法では、サーチ範囲すなわち信号サーチを実行するコード位相範囲および周波数範囲の全体をサーチできるまでは、各コード位相、周波数での積算時間は一定である。そして、このような全体サーチを少なくとも１回（場合によっては複数回）終了させた後に、目的とする信号が検出できなければ、積算時間を長くして、信号サーチを実行する。 As described above, in the conventional signal search method, the integration time for each code phase and frequency is constant until the search range, that is, the entire code phase range and frequency range for performing signal search can be searched. Then, after completing the entire search at least once (in some cases, a plurality of times), if the target signal cannot be detected, the signal search is executed by extending the integration time.
　また、弱信号を検出する場合には、強信号検出用の積算時間よりも、積算時間を長く設定する。 Also, when a weak signal is detected, the integration time is set longer than the integration time for strong signal detection.
米国特許７６２３０７０号明細書US Patent 7623070
　しかしながら、従来の信号サーチ方法では、上述のように、サーチ範囲全域に亘り、同じ積算時間で積算相関値を算出するため、例えば積算時間を短く設定したとしても弱信号等を検出できないため、サーチ範囲全域を繰り返しサーチしなければならず、結果的に積算時間が長くなる。一方で、積算時間を長く設定すると、コード位相、周波数の二次元範囲における各積算相関値算出点での積算時間が長くなり、サーチ範囲全域に対するサーチ時間が長くなる。 However, in the conventional signal search method, since the integrated correlation value is calculated with the same integration time over the entire search range as described above, for example, even if the integration time is set short, a weak signal or the like cannot be detected. The entire range must be searched repeatedly, resulting in a longer integration time. On the other hand, if the integration time is set longer, the integration time at each integration correlation value calculation point in the two-dimensional range of code phase and frequency becomes longer, and the search time for the entire search range becomes longer.
　また、サーチ範囲全域に亘り、同じ積算時間で積算相関値を算出する場合には、クロスコリレーションの影響を受けやすく、上述の誤検出を生じる確率を低下させることができない。 In addition, when the integrated correlation value is calculated in the same integration time over the entire search range, it is easily affected by cross-correlation, and the probability of causing the above-described erroneous detection cannot be reduced.
　したがって、本発明の目的は、従来方法よりも短いサーチ時間で、クロスコリレーションによる誤検出の可能性を低下させ、より正確に目的信号を捕捉できる信号サーチ方法を提供することにある。 Therefore, an object of the present invention is to provide a signal search method capable of capturing a target signal more accurately by reducing the possibility of erroneous detection due to cross-correlation in a shorter search time than the conventional method.
　この発明は、目的の信号を捕捉するための信号サーチ方法であって、積算時間決定工程と、相関値算出工程と、積算相関値算出工程を有する。積算時間決定工程では、追尾中の信号の周波数とサーチ対象の周波数との周波数差に応じて、該サーチ対象の周波数での積算時間を設定する。相関値算出工程は、目的の信号のレプリカ信号と受信信号との相関値を算出する。積算相関値算出工程では、積算時間決定工程で設定された積算時間で相関値を積算することにより積算相関値を算出する。 The present invention is a signal search method for capturing a target signal, and includes an integration time determination step, a correlation value calculation step, and an integration correlation value calculation step. In the integration time determination step, the integration time at the search target frequency is set according to the frequency difference between the frequency of the signal being tracked and the search target frequency. The correlation value calculating step calculates a correlation value between the replica signal of the target signal and the received signal. In the integrated correlation value calculating step, the integrated correlation value is calculated by integrating the correlation value with the integrated time set in the integrated time determining step.
　この方法では、追尾中の信号の周波数と現在サーチ対象となっている周波数との差によって、現在サーチ対象となっている周波数での相関値の積算時間が決定される。すなわち、追尾中の信号の周波数と現在サーチ対象となっている周波数との差によって、積算時間を変化させることができる。これにより、追尾中の信号による積算相関値への影響を低減することができる。さらに、積算時間が適切に設定されることで、単に積算時間を一定にする場合よりも、周波数帯域全域に亘るトータルの積算時間を短縮することが可能になる。 In this method, the integration time of the correlation value at the frequency currently being searched is determined by the difference between the frequency of the signal being tracked and the frequency currently being searched. That is, the integration time can be changed by the difference between the frequency of the signal being tracked and the frequency currently being searched. Thereby, the influence on the integrated correlation value by the signal being tracked can be reduced. Furthermore, by setting the integration time appropriately, it is possible to shorten the total integration time over the entire frequency band, compared to simply making the integration time constant.
　また、この発明の信号サーチ方法の積算時間決定工程は、周波数区間決定工程、区分判定工程、および決定工程を有する。周波数区間決定工程では、追尾中の信号の周波数を基準として、サーチ対象の周波数との差に応じて、サーチ対象の周波数が選択的に該当し得る複数の周波数区間を決定する。区分判定工程では、サーチ対象の周波数が複数の周波数区間のいずれに属するかを判定する。決定工程では、周波数区間毎に積算時間を設定する。 Further, the integration time determining step of the signal search method of the present invention includes a frequency interval determining step, a segment determining step, and a determining step. In the frequency section determining step, a plurality of frequency sections to which the search target frequency can selectively correspond are determined based on the difference from the search target frequency based on the frequency of the signal being tracked. In the classification determination step, it is determined to which of a plurality of frequency sections the frequency to be searched belongs. In the determination step, the integration time is set for each frequency section.
　この方法では、サーチ対象の周波数を複数の周波数区間に分け、周波数区間毎に積算時間を決定している。これにより、個別のサーチ周波数毎に詳細に積算時間を決定する場合に対して、信号サーチ性能をあまり低下させることなく、積算時間の決定工程を簡素化して、短縮化できる。 In this method, the search target frequency is divided into a plurality of frequency sections, and the integration time is determined for each frequency section. Thereby, compared with the case where the integration time is determined in detail for each individual search frequency, the integration time determination process can be simplified and shortened without significantly reducing the signal search performance.
　また、この発明の信号サーチ方法の周波数区間決定工程では、追尾中の信号により積算相関値の算出時に現れる相関ピークとなる周波数の繰り返し間隔に基づいて、複数の周波数区間を設定する工程を有する。 Further, the frequency interval determination step of the signal search method of the present invention includes a step of setting a plurality of frequency intervals based on the repetition interval of the frequency that becomes the correlation peak that appears when the integrated correlation value is calculated by the signal being tracked.
　区分判定工程は、サーチ対象の周波数と追尾中の信号の周波数との周波数差分値を算出する工程と、周波数差分値が複数の周波数区間のいずれの範囲内にあるかを判定する工程と、を有する。 The classification determination step includes a step of calculating a frequency difference value between the frequency to be searched and the frequency of the signal being tracked, and a step of determining in which range of the plurality of frequency sections the frequency difference value is. Have.
　この方法では、追尾中の信号により積算相関値の算出時に現れる相関ピークの周波数が所定間隔で繰り返される場合、すなわちクロスコリレーションが生じる場合のサーチ方法を具体的に示している。このような場合、相関ピークの周波数間での相関値の変化は同じであるので、１組の相関ピークの周波数間での周波数区間を設定すれば、他の相関ピークの周波数間に対しても同様に適用でき、信号サーチ性能を低下させることなく、周波数帯域全域に対する周波数区間の設定をより簡素化且つ短縮化できる。 This method specifically shows a search method in the case where the frequency of the correlation peak that appears when the integrated correlation value is calculated by the signal being tracked is repeated at predetermined intervals, that is, when cross-correlation occurs. In such a case, since the change in the correlation value between the frequencies of the correlation peaks is the same, if a frequency section between the frequencies of one set of correlation peaks is set, the correlation between the frequencies of other correlation peaks is also The present invention can be similarly applied, and the setting of the frequency section for the entire frequency band can be simplified and shortened without degrading the signal search performance.
　また、この発明の信号サーチ方法の積算時間決定工程では、予め行った予備サーチにより検出された予備検出信号の周波数が複数の周波数区間のそれぞれに属する数を検出する工程と、周波数区間に属する予備検出信号の数に応じて積算時間を補正する工程と、を有する。 Further, in the integration time determining step of the signal search method of the present invention, a step of detecting the number of frequencies of the preliminary detection signal detected by the preliminary search performed in advance belonging to each of a plurality of frequency intervals, and a reserve belonging to the frequency interval And correcting the integration time according to the number of detection signals.
　この方法では、予備サーチ結果から、各周波数区間におけるサーチ対象の信号の有無の可能性が、ある程度分かる。したがって、予備サーチ結果を用いること、すなわちサーチ対象の信号の有無の可能性に基づいて、積算時間を最適化することが可能になる。 In this method, the possibility of the presence or absence of a search target signal in each frequency section can be understood to some extent from the preliminary search result. Accordingly, it is possible to optimize the integration time based on the use of the preliminary search result, that is, based on the possibility of presence or absence of a search target signal.
　また、この発明の信号サーチ方法の積算時間決定工程では、予備検出信号の信号強度を検出する工程と、予備検出信号の信号強度が予め設定された複数の信号強度区分のそれぞれに属する数を検出する工程と、信号強度区分毎に属する予備検出信号の数の分布に応じて積算時間をさらに補正する工程と、を有する。 In addition, in the integration time determination step of the signal search method of the present invention, the step of detecting the signal strength of the preliminary detection signal and the number of signal strengths of the preliminary detection signal belonging to each of a plurality of preset signal strength categories are detected. And a step of further correcting the integration time in accordance with the distribution of the number of preliminary detection signals belonging to each signal intensity category.
　この方法では、さらに予備サーチ結果で検出された予備検出信号の信号強度も用いることで、積算時間のさらなる最適化が可能になる。 In this method, the integration time can be further optimized by using the signal intensity of the preliminary detection signal detected from the preliminary search result.
　また、この発明の信号サーチ方法では、サーチ対象の周波数を、繰り返し間隔と同じ離間間隔で複数設定する工程を有する。そして、複数のサーチ対象の周波数で平行して、相関値算出工程を実行する。 In addition, the signal search method of the present invention includes a step of setting a plurality of search target frequencies at the same interval as the repetition interval. Then, the correlation value calculating step is executed in parallel at a plurality of search target frequencies.
　この方法では、複数のサーチ対象の周波数を１グループとして、グループ内の各サーチ対象の周波数に対して同時に積算相関値を算出できる。これにより、信号サーチ処理を更に短縮化できる。 In this method, a plurality of search target frequencies are regarded as one group, and an integrated correlation value can be calculated simultaneously for each search target frequency in the group. Thereby, the signal search process can be further shortened.
　また、この発明の信号サーチ方法では、目的の信号は、ＧＰＳ衛星毎に放送されるＧＰＳ信号である。 In the signal search method of the present invention, the target signal is a GPS signal broadcast for each GPS satellite.
　この方法では、具体的に目的の信号（サーチ対象の信号）がＧＰＳ信号であることを示している。すなわち、ＧＰＳ信号の捕捉におけるクロスコリレーションによる影響を低減させ、ＧＰＳ信号を、より確実に捕捉することを示している。 This method specifically indicates that the target signal (search target signal) is a GPS signal. That is, it shows that the influence of cross-correlation in capturing the GPS signal is reduced, and the GPS signal is captured more reliably.
　この発明によれば、従来方法よりも短いサーチ時間で目的のＧＰＳ信号を捕捉でき、クロスコリレーションによる誤検出を殆ど生じることなく、目的信号を正確に捕捉できる。 According to the present invention, the target GPS signal can be captured in a shorter search time than the conventional method, and the target signal can be accurately captured with almost no erroneous detection due to cross-correlation.
本発明の実施形態に係る信号サーチ方法のフローチャートである。3 is a flowchart of a signal search method according to an embodiment of the present invention. 積算時間の変化によるクロスコリレーションの相関特性を示す図である。It is a figure which shows the correlation characteristic of the cross correlation by the change of integration time. 周波数区間の設定概念を説明するための図である。It is a figure for demonstrating the setting concept of a frequency area. 積算時間設定用マップの一例を示す図である。It is a figure which shows an example of the map for integration time setting. 積層時間変更用マップの形成工程のフローチャートである。It is a flowchart of the formation process of the lamination time change map. 本実施形態のサーチ処理における相関処理方法を行うためのコード位相、周波数設定概念を説明するための図である。It is a figure for demonstrating the code phase and frequency setting concept for performing the correlation processing method in the search process of this embodiment. 周波数区間の判定処理および積算時間の設定処理を示すフローチャートである。It is a flowchart which shows the determination process of a frequency area, and the setting process of integration time. 周波数区間の判定概念および積算時間の設定概念を説明するための図である。It is a figure for demonstrating the determination concept of a frequency area, and the setting concept of integration time. 信号強度区分の設定概念を説明するための図である。It is a figure for demonstrating the setting concept of a signal strength division. 信号強度区分も含めた積算時間設定用マップの一例を示す図である。It is a figure which shows an example of the map for integration time setting also including a signal strength division. 本発明の実施形態に係るＧＰＳ信号受信装置１の構成を示すブロック図である。It is a block diagram which shows the structure of the GPS signal receiver 1 which concerns on embodiment of this invention. ＧＰＳ信号受信装置１を備える情報機器端末１００の構成を示すブロック図である。It is a block diagram which shows the structure of the information equipment terminal 100 provided with the GPS signal receiver 1. FIG.
　本発明の実施形態に係る信号サーチ方法について、図を参照して説明する。なお、本実施形態では、ＧＰＳ衛星から送信されるＧＰＳ信号のサーチ方法について説明する。また、本実施形態では、説明を簡略化するために、本実施形態に示す信号サーチの開始時点において、追尾中のＧＰＳ信号が１個である場合について説明する。 A signal search method according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a method for searching for a GPS signal transmitted from a GPS satellite will be described. Further, in this embodiment, for the sake of simplification of description, a case will be described where there is one tracking GPS signal at the start of the signal search shown in this embodiment.
　図１は本実施形態の信号サーチ方法のフローチャートである。図１に示すように、本実施形態の信号サーチ方法では、まず、追尾中のＧＰＳ信号の周波数ＦＢを取得する（Ｓ１０１）。この追尾中のＧＰＳ信号が本実施形態で示す信号サーチ時でのクロスコリレーションの要因となり得る信号である。 FIG. 1 is a flowchart of the signal search method of this embodiment. As shown in FIG. 1, the signal search method of this embodiment first obtains the frequency F B of the GPS signal in the tracking (S101). The GPS signal being tracked is a signal that can cause cross-correlation at the time of signal search shown in the present embodiment.
　このようなクロスコリレーションでは、積算相関値が図２に示すような周波数特性を有する。図２は、積算時間の変化によるクロスコリレーションの相関特性を示す図である。図２（Ｃ），（Ｄ）に示す特性が得られる積算時間は、図２（Ａ），（Ｂ）の特性が得られる積算時間よりも長く（約２倍）、図２（Ｅ），（Ｆ）に示す特性が得られる積算時間は、図２（Ｃ），（Ｄ）に示す特性が得られる積算時間よりも更に長い（更に約２倍）。また、図２（Ｂ）は図２（Ａ）の周波数方向拡大図であり、図２（Ｄ）は図２（Ｃ）の周波数方向拡大図であり、図２（Ｆ）は図２（Ｅ）の周波数方向拡大図である。 In such cross-correlation, the integrated correlation value has a frequency characteristic as shown in FIG. FIG. 2 is a diagram illustrating a correlation characteristic of cross correlation due to a change in integration time. The accumulated time for obtaining the characteristics shown in FIGS. 2C and 2D is longer than the accumulated time for obtaining the characteristics shown in FIGS. 2A and 2B (about twice). The integration time for obtaining the characteristics shown in (F) is longer (further about twice) than the integration time for obtaining the characteristics shown in FIGS. 2B is an enlarged view in the frequency direction of FIG. 2A, FIG. 2D is an enlarged view in the frequency direction of FIG. 2C, and FIG. 2F is an enlarged view of FIG. FIG.
　図２に示すように、クロスコリレーションでは、積算相関値が極大となるピーク周波数が１０００Ｈｚ間隔で現れ、当該ピーク周波数から離間するほど、積算相関値は低下する。そして、ピーク周波数から５００Ｈｚ離れた周波数、言い換えれば隣り合うピーク周波数の中間周波数で、積算相関値が極小となる。また、クロスコリレーションの相関特性は、ピーク周波数を基準にして、高周波数側と低周波数側とで同じ特性となる。言い換えれば、クロスコリレーションの相関特性は、積算相関値が極小となる周波数に対して、高周波数側と低周波数側とで同じ特性となる。 As shown in FIG. 2, in cross-correlation, the peak frequency at which the integrated correlation value becomes maximum appears at intervals of 1000 Hz, and the integrated correlation value decreases as the distance from the peak frequency increases. Then, the integrated correlation value is minimized at a frequency 500 Hz away from the peak frequency, in other words, at an intermediate frequency between adjacent peak frequencies. Further, the cross correlation correlation characteristics are the same on the high frequency side and the low frequency side with reference to the peak frequency. In other words, the correlation characteristics of cross correlation are the same characteristics on the high frequency side and the low frequency side with respect to the frequency at which the integrated correlation value is minimized.
　次に、このようなクロスコリレーション特有の積算相関値特性を利用して、追尾中のＧＰＳ信号の周波数ＦＢに基づいて、図３に示すように周波数区間を決定する（Ｓ１０２）。図３は周波数区間の設定概念を説明するための図である。 Then, by utilizing such a cross-correlation characteristic of the integrated correlation value characteristic, based on the frequency F B of the GPS signal in the tracking, determining the frequency interval, as shown in FIG. 3 (S102). FIG. 3 is a diagram for explaining the concept of setting frequency intervals.
　図３に示すように、本実施形態の信号サーチ方法では、追尾中のＧＰＳ信号（クロスコリレーションの起因となる信号）の周波数を基準の周波数（０Ｈｚ）として、当該基準の周波数から５００Ｈｚ離間する周波数範囲を、第１周波数区間ＡＲｃ、第２周波数区間ＡＲｎ、および第３周波数区間ＡＲｆに分割して設定する。 As shown in FIG. 3, in the signal search method of the present embodiment, the frequency of the GPS signal being tracked (the signal causing the cross correlation) is set as a reference frequency (0 Hz), and is separated from the reference frequency by 500 Hz. The frequency range is set by being divided into a first frequency interval ARc, a second frequency interval ARn, and a third frequency interval ARf.
　第１周波数区間ＡＲｃは、概念的には、クロスコリレーションの影響を最も受けやすく、クロスコリレーションの周波数に対して極近接する周波数区間である。第１周波数区間ＡＲｃは基準の周波数から第１閾値周波数Ｆｃまでの周波数帯域で設定される。 The first frequency section ARc is conceptually a frequency section that is most susceptible to cross-correlation and is very close to the cross-correlation frequency. The first frequency section ARc is set in the frequency band from the reference frequency to the first threshold frequency Fc.
　第２周波数区間ＡＲｎは、概念的には、クロスコリレーションの影響を受ける可能性ある程度有り、クロスコリレーションの周波数に対して極近接区間よりは離間しているが、ある程度近接する周波数区間である。第２周波数区間ＡＲｎは、第１閾値周波数Ｆｃから第２閾値周波数Ｆｎ（＜Ｆｃ）までの周波数帯域で設定される。 The second frequency section ARn conceptually has a certain degree of possibility of being affected by cross-correlation, and is a frequency section that is separated from the close proximity section to the cross-correlation frequency but is close to a certain degree. . The second frequency interval ARn is set in a frequency band from the first threshold frequency Fc to the second threshold frequency Fn (<Fc).
　第３周波数区間ＡＲｆは、概念的には、クロスコリレーションの影響を殆ど受けることなく、クロスコリレーションの周波数に対して離間している周波数区間である。第３周波数区間ＡＲｆは、第２閾値周波数Ｆｎから５００Ｈｚまでの周波数帯域で設定される。 The third frequency section ARf is conceptually a frequency section that is hardly affected by the cross-correlation and is separated from the cross-correlation frequency. The third frequency section ARf is set in a frequency band from the second threshold frequency Fn to 500 Hz.
　なお、第１閾値周波数Ｆｃ、第２閾値周波数Ｆｎは、積算時間に基づいて適宜設定される。例えば、クロスコリレーションのメインローブに略相当する周波数帯域が第１周波数区間ＡＲｃとなるように、第１閾値周波数Ｆｃが設定される。また、当該メインローブに隣り合うサイドローブに略相当する周波数帯域が第２周波数区間ＡＲｎとなるように、第２閾値周波数Ｆｎが設定される。 The first threshold frequency Fc and the second threshold frequency Fn are set as appropriate based on the integration time. For example, the first threshold frequency Fc is set so that the frequency band substantially corresponding to the main lobe of cross correlation becomes the first frequency section ARc. Further, the second threshold frequency Fn is set so that the frequency band substantially corresponding to the side lobe adjacent to the main lobe becomes the second frequency section ARn.
　そして、積算時間が変化すれば、図２に示すように、クロスコリレーションの相関特性は変化するので、この相関特性の変化に応じて、第１閾値周波数Ｆｃ、第２閾値周波数Ｆｎを変化させればよい。例えば、積算時間が長くなると、メインローブおよびサイドローブの幅が狭くなるので、第１閾値周波数Ｆｃ、第２閾値周波数Ｆｎを、より小さな値に設定すればよい。 If the integration time changes, the correlation characteristics of the cross correlation change as shown in FIG. 2. Therefore, the first threshold frequency Fc and the second threshold frequency Fn are changed according to the change of the correlation characteristics. Just do it. For example, as the integration time becomes longer, the width of the main lobe and the side lobe becomes narrower, so the first threshold frequency Fc and the second threshold frequency Fn may be set to smaller values.
　次に、本実施形態の信号サーチ方法では、予備サーチによって検出された予備検出信号の周波数を取得し、図４に示すような積算時間変更用のマップ形成を行う（Ｓ１０３）。図４は積算時間設定用マップの一例を示す図である。また、図５は、積層時間変更用マップの形成工程のフローチャートである。 Next, in the signal search method of this embodiment, the frequency of the preliminary detection signal detected by the preliminary search is acquired, and a map for changing the integration time as shown in FIG. 4 is formed (S103). FIG. 4 is a diagram showing an example of the integrated time setting map. FIG. 5 is a flowchart of the process for forming the stacking time changing map.
　予備サーチによって検出された予備検出信号の周波数Ｆを取得すると、当該予備検出信号の周波数Ｆと、追尾中のＧＰＳ信号の周波数ＦＢとの差分値（周波数差分値Ｄｆ（Ｆ））を算出する。この際、複数の予備検出信号があれば、個々の予備検出信号毎に周波数差分値Ｄｆ（Ｆ）を算出する（Ｓ３０１）。 When acquiring the frequency F of the detected pre-detection signal by the preliminary search, calculates the frequency F of the preliminary detection signals, difference values between the frequency F B of the GPS signal in tracking (frequency difference Df (F)) . At this time, if there are a plurality of preliminary detection signals, the frequency difference value Df (F) is calculated for each preliminary detection signal (S301).
　予備検出信号の周波数差分値Ｄｆ（Ｆ）は次式から得られる。
　Ｄｆ（Ｆ）＝（ＡＢＳ（Ｆ－ＦＢ））／１０００　［Ｈｚ］
　ここで、ＡＢＳ（　）は、絶対値演算を表す記号である。 The frequency difference value Df (F) of the preliminary detection signal is obtained from the following equation.
Df (F) = (ABS (F−F B )) / 1000 [Hz]
Here, ABS () is a symbol representing absolute value calculation.
　次に、予備検出信号の周波数差分値が０Ｈｚから５００Ｈｚまでの間の値となるように規格化し、規格化周波数差分値Δｆ（Ｆ）を算出する。予備検出信号の規格化周波数差分値Δｆ（Ｆ）は次式から得られる。なお、Ｍｏｄ（　）は余り表す記号である。
　Ｉｆ　Ｍｏｄ（Ｄｆ（Ｆ））≧５００　［Ｈｚ］
　　　　　　　　　　Δｆ（Ｆ）＝ＡＢＳ（Ｄｆ（Ｆ）－１０００）
　Ｅｌｓｅ　Ｍｏｄ（Ｄｆ（Ｆ））＜５００　［Ｈｚ］
　　　　　　　　　　Δｆ（Ｆ）＝Ｍｏｄ（Ｄｆ（Ｆ））
　このように算出された各予備検出信号の規格化周波数差分値Δｆ（Ｆ）を、第１閾値周波数Ｆｃ、第２閾値周波数Ｆｎと比較する（Ｓ３０２）。 Next, normalization is performed so that the frequency difference value of the preliminary detection signal is a value between 0 Hz and 500 Hz, and a normalized frequency difference value Δf (F) is calculated. The normalized frequency difference value Δf (F) of the preliminary detection signal is obtained from the following equation. Mod () is a symbol that represents the remainder.
If Mod (Df (F)) ≧ 500 [Hz]
Δf (F) = ABS (Df (F) −1000)
Else Mod (Df (F)) <500 [Hz]
Δf (F) = Mod (Df (F))
The normalized frequency difference value Δf (F) of each preliminary detection signal calculated in this way is compared with the first threshold frequency Fc and the second threshold frequency Fn (S302).
　予備検出信号の規格化周波数差分値Δｆ（Ｆ）が第１閾値周波数Ｆｃよりも低ければ（Ｓ３０３：Ｙｅｓ）、当該予備検出信号は第１周波数区間ＡＲｃ内と判定し（Ｓ３０５）、第１周波数区間ＡＲｃの予備検出信号数が＋１カウントされる（Ｓ３０６）。 If the normalized frequency difference value Δf (F) of the preliminary detection signal is lower than the first threshold frequency Fc (S303: Yes), the preliminary detection signal is determined to be within the first frequency interval ARc (S305), and the first frequency The number of preliminary detection signals in the section ARc is incremented by 1 (S306).
　予備検出信号の規格化周波数差分値Δｆ（Ｆ）が第１閾値周波数Ｆｃ以上であり（Ｓ３０３：Ｎｏ）、第２閾値周波数Ｆｎよりも低ければ（Ｓ３０４：Ｙｅｓ）、当該予備検出信号は第２周波数区間ＡＲｎ内と判定し（Ｓ３０７）、第２周波数区間ＡＲｎの予備検出信号数が＋１カウントされる（Ｓ３０８）。 If the normalized frequency difference value Δf (F) of the preliminary detection signal is equal to or higher than the first threshold frequency Fc (S303: No) and lower than the second threshold frequency Fn (S304: Yes), the preliminary detection signal is the second threshold frequency Fn. It is determined that it is within the frequency interval ARn (S307), and the number of preliminary detection signals in the second frequency interval ARn is incremented by 1 (S308).
　予備検出信号の規格化周波数差分値Δｆ（Ｆ）が第１閾値周波数Ｆｃ以上であり（Ｓ３０３：Ｎｏ）、第２閾値周波数Ｆｎ以上であれば（Ｓ３０４：Ｎｏ）、当該予備検出信号は第３周波数区間ＡＲｆ内と判定し（Ｓ３０９）、第３周波数区間ＡＲｆの予備検出信号数が＋１カウントされる（Ｓ３１０）。 If the normalized frequency difference value Δf (F) of the preliminary detection signal is equal to or higher than the first threshold frequency Fc (S303: No) and is equal to or higher than the second threshold frequency Fn (S304: No), the preliminary detection signal is the third threshold frequency Fn. It is determined that it is within the frequency interval ARf (S309), and the number of preliminary detection signals in the third frequency interval ARf is counted by +1 (S310).
　このような予備検出信号がどの周波数区間に該当するかを処理は、全ての予備検出信号に対して行われ（Ｓ３１１：Ｙｅｓ）、当該判断処理が行われていない予備検出信号がある場合は（Ｓ３１１：Ｎｏ）、全ての予備検出信号に対する判断処理が終わるまで、上述のステップＳ３０２からの処理を繰り返す。 Processing for determining which frequency section the preliminary detection signal corresponds to is performed for all the preliminary detection signals (S311: Yes), and when there is a preliminary detection signal for which the determination processing is not performed ( S311: No), the above-described processing from step S302 is repeated until determination processing for all the preliminary detection signals is completed.
　このような処理を行うことで、第１周波数区間ＡＲｃ、第２周波数区間ＡＲｎ、第３周波数区間ＡＲｆ毎に存在する予備検出信号数のマップ（図４参照）が形成される。 By performing such processing, a map (see FIG. 4) of the number of preliminary detection signals existing for each of the first frequency section ARc, the second frequency section ARn, and the third frequency section ARf is formed.
　次に、マップに基づいて、第１周波数区間ＡＲｃの積算時間Ｔｃ、第２周波数区間ＡＲｎの積算時間Ｔｎ、および第３周波数区間ＡＲｆの積算時間Ｔｆを設定する。 Next, based on the map, the integration time Tc of the first frequency interval ARc, the integration time Tn of the second frequency interval ARn, and the integration time Tf of the third frequency interval ARf are set.
　ここで、図４に示すように、第１周波数区間ＡＲｃ、第２周波数区間ＡＲｎの両方に予備検出信号がある場合、第１周波数区間ＡＲｃの積算時間Ｔｃ、第２周波数区間ＡＲｎの積算時間Ｔｎ、および第３周波数区間ＡＲｆの積算時間Ｔｆは、Ｔｃ＞Ｔｎ＞Ｔｆの関係となるように、設定される。 Here, as shown in FIG. 4, when there are preliminary detection signals in both the first frequency interval ARc and the second frequency interval ARn, the integration time Tc of the first frequency interval ARc and the integration time Tn of the second frequency interval ARn. , And the integration time Tf of the third frequency interval ARf is set so as to satisfy the relationship of Tc> Tn> Tf.
　このような設定を行うことで、クロスコリレーションの影響を受けやすい周波数区間ほど、積算時間が長くなるように設定される。ここで、上述の図２に示すように、積算時間が長くなるほど、クロスコリレーションによる相関特性のピークが急峻になることが分かる。このため、積算時間を長くするほど、周波数軸上での信号検出の分解能が向上する。 行 う By making such settings, the integration time is set longer for frequency sections that are more susceptible to cross-correlation. Here, as shown in FIG. 2 described above, it can be seen that the peak of the correlation characteristic due to cross-correlation becomes steeper as the integration time becomes longer. For this reason, the longer the integration time, the higher the resolution of signal detection on the frequency axis.
　したがって、本実施形態のように積算時間を設定することで、クロスコリレーションのピーク周波数に極近接する周波数帯や、クロスコリレーションのピーク周波数に近接する周波数帯であっても、それぞれの周波数区間に応じて適切にクロスコリレーションの影響が低減され、目的とするＧＰＳ信号を、より正確に検出し、捕捉することができる。 Therefore, by setting the integration time as in this embodiment, even in a frequency band that is extremely close to the peak frequency of cross correlation or a frequency band that is close to the peak frequency of cross correlation, each frequency section Accordingly, the influence of cross-correlation is appropriately reduced, and the target GPS signal can be detected and captured more accurately.
　次に、サーチ周波数Ｆｓｉｇを走査しながら、受信信号とレプリカ信号（目的のＧＰＳ信号のコードと同じコードの信号）との相関処理を実行する（Ｓ１０５）。そして、得られた相関値を、上述のように設定された積算時間で積算することにより、積算相関値を算出する（Ｓ１０６）。この際、上述の周波数区間ＡＲｃ，ＡＲｎ，ＡＲｆに応じてサーチ周波数Ｆｓｉｇ毎に積算時間を設定する。 Next, while scanning the search frequency F sig , correlation processing between the received signal and the replica signal (a signal having the same code as the code of the target GPS signal) is executed (S105). Then, the integrated correlation value is calculated by integrating the obtained correlation value for the integration time set as described above (S106). At this time, an integration time is set for each search frequency F sig according to the above-described frequency sections ARc, ARn, and ARf.
　ここで、本実施形態で実行する相関処理時のサーチ周波数Ｆｓｉｇの設定方法および相関処理方法を説明する。図６は本実施形態のサーチ処理における相関処理方法を行うためのコード位相、周波数設定概念を説明するための図である。 Here, a search frequency F sig setting method and correlation processing method during correlation processing executed in the present embodiment will be described. FIG. 6 is a diagram for explaining the concept of setting the code phase and frequency for performing the correlation processing method in the search processing of this embodiment.
　図６に示すように、本実施形態では、コード位相に関しては、１０２３［ｃｈｉｐ］のＣ／Ａコードに対して、０．５［ｃｈｉｐ］間隔からなる２０４６点で、同時並行して相関処理を実行し積算相関値を算出する。すなわち、サーチ周波数Ｆｓｉｇを設定すると、当該サーチ周波数Ｆｓｉｇにおける２０４６点で同時並行して積算相関値が算出される。これにより、前コード位相範囲を同時に相関処理できる。 As shown in FIG. 6, in the present embodiment, with respect to the code phase, the correlation process is simultaneously performed at 2046 points having an interval of 0.5 [chip] with respect to the C / A code of 1023 [chip]. Run to calculate the integrated correlation value. That is, when the search frequency F sig is set, the integrated correlation value is calculated in parallel at 2046 points at the search frequency F sig . As a result, the preceding code phase range can be correlated simultaneously.
　さらに、サーチ周波数は、１０００Ｈｚ間隔で設定された８点を１グループとして、同時並行して相関処理を実行し積算相関値を算出する。具体的な例としては、図６に示すように、１０００Ｈｚ間隔からなるサーチ周波数Ｆｓｉｇ０１１，Ｆｓｉｇ０１２，Ｆｓｉｇ０１３，Ｆｓｉｇ０１４，Ｆｓｉｇ０１５，Ｆｓｉｇ０１６，Ｆｓｉｇ０１７，Ｆｓｉｇ０１８のグループＧｒ１において、同時に相関処理が実行される。 Furthermore, the search frequency is calculated by calculating the integrated correlation value by executing the correlation process in parallel with 8 points set at 1000 Hz intervals as one group. As a specific example, as shown in FIG. 6, search frequencies F sig 011, F sig 012, F sig 013, F sig 014, F sig 015, F sig 016, F sig 017, F sig are shown in FIG. In the group Gr1 of 018, correlation processing is executed simultaneously.
　次に、グループＧｒ１に対して、サーチ周波数を５０ＨｚシフトさせたグループＧｒ２（サーチ周波数Ｆｓｉｇ０２１を含むグループ）において、８点で同時に相関処理が実行される。 Next, in the group Gr2 (a group including the search frequency F sig 021) obtained by shifting the search frequency by 50 Hz with respect to the group Gr1, the correlation processing is simultaneously performed at 8 points.
　次に、グループＧｒ２に対して、サーチ周波数を５０ＨｚシフトさせたグループＧｒ３（サーチ周波数Ｆｓｉｇ０３１を含むグループ）において、８点で同時に相関処理が実行される。 Next, in the group Gr3 (group including the search frequency F sig 031) in which the search frequency is shifted by 50 Hz with respect to the group Gr2, the correlation processing is simultaneously executed at 8 points.
　このような相関処理を、グループＧｒ１からグループＧｒ１９まで順次実行していくことで、サーチ周波数の全域を網羅する１チャンネル分の積算相関値を得る。そして、１チャンネル分の相関処理が終了すると、再度グループＧｒ１からの相関処理が、順次栗かして実行される。 Such correlation processing is sequentially executed from the group Gr1 to the group Gr19, thereby obtaining an integrated correlation value for one channel covering the entire search frequency. When the correlation processing for one channel is completed, the correlation processing from the group Gr1 is sequentially executed again.
　このように、１０００Ｈｚ間隔からなる複数のサーチ周波数Ｆｓｉｇで同時に相関処理を実行することで、個別に順次実行するよりも、１チャンネル分の相関処理（積層相関値の算出）を短縮化できる。 In this way, by performing the correlation process simultaneously with a plurality of search frequencies F sig having an interval of 1000 Hz, the correlation process for one channel (calculation of the laminated correlation value) can be shortened as compared with the sequential execution individually.
　さらに、上述のクロスコリレーションのピーク周波数が１０００［Ｈｚ］間隔であるので、同じグループＧｒに含まれる各サーチ周波数Ｆｓｉｇは、同じ周波数区間に該当する。したがって、グループＧｒに含まれる全てサーチ周波数に対して、周波数区間を判定する処理（積算時間を決定する処理）を個別に行う必要が無く、代表する１つのサーチ周波数Ｆｓｉｇで実行すればよい。例えば、グループＧｒ１の場合、サーチ周波数Ｆｓｉｇ０１１，Ｆｓｉｇ０１２，Ｆｓｉｇ０１３，Ｆｓｉｇ０１４，Ｆｓｉｇ０１５，Ｆｓｉｇ０１６，Ｆｓｉｇ０１７，Ｆｓｉｇ０１８の全てに対して周波数区間の判定を行わなくても、サーチ周波数Ｆｓｉｇ０１１だけ周波数区間の判定をして積算時間を決定し、他のサーチ周波数Ｆｓｉｇ０１２，Ｆｓｉｇ０１３，Ｆｓｉｇ０１４，Ｆｓｉｇ０１５，Ｆｓｉｇ０１６，Ｆｓｉｇ０１７，Ｆｓｉｇ０１８に、サーチ周波数Ｆｓｉｇ０１１の周波数区間（積算時間）を適用すればよい。これにより、信号サーチ処理を簡素化でき、信号サーチ処理の短縮化が可能になる。 Furthermore, since the cross-correlation peak frequency is 1000 [Hz], the search frequencies F sig included in the same group Gr correspond to the same frequency section. Therefore, it is not necessary to individually perform a process of determining a frequency section (a process of determining the integration time) for all search frequencies included in the group Gr, and it is sufficient to perform the process with one representative search frequency F sig . For example, in the case of the group Gr1, the determination of the frequency interval is performed for all of the search frequencies F sig 011, F sig 012, F sig 013, F sig 014, F sig 015, F sig 016, F sig 017, and F sig 018. Even if not performed, the frequency interval is determined by the search frequency F sig 011 to determine the integration time, and the other search frequencies F sig 012, F sig 013, F sig 014, F sig 015, F sig 016, F sig 016 A frequency interval (integrated time) of the search frequency F sig 011 may be applied to 017, F sig 018. Thereby, the signal search process can be simplified and the signal search process can be shortened.
　このように、設定されるサーチ周波数Ｆｓｉｇに対して、上述のいずれの周波数区間に該当するかを判定し、積算時間を決定する。図７は周波数区間の判定処理および積算時間の設定処理を示すフローチャートである。 Thus, it is determined which frequency section corresponds to the set search frequency F sig to determine the integration time. FIG. 7 is a flowchart showing a frequency interval determination process and an integration time setting process.
　追尾中のＧＰＳ信号の周波数ＦＢとサーチ周波数Ｆｓｉｇとの周波数差分値Ｄｆを算出し、規格化周波数差分値Δｆｓｉｇを算出する（Ｓ４０１）。具体的には、上述の予備検出信号の規格化周波数差分値Δｆ（Ｆ）と同様の処理を行う。 It calculates a frequency difference Df between the frequency F B and the search frequency F sig of the GPS signal in the tracking, calculates the normalized frequency difference Δf sig (S401). Specifically, the same processing as the above-described normalized frequency difference value Δf (F) of the preliminary detection signal is performed.
　追尾中のＧＰＳ信号の周波数ＦＢとサーチ周波数Ｆｓｉｇとの周波数差分値Ｄｆを算出する。 It calculates the frequency difference Df between the frequency F B and the search frequency F sig of the GPS signal in the tracking.
　周波数差分値Ｄｆは次式から得られる。
　Ｄｆ＝（ＡＢＳ（Ｆｓｉｇ－ＦＢ））／１０００　［Ｈｚ］
　次に、周波数差分値が０Ｈｚから５００Ｈｚまでの間の値となるように規格化し、規格化周波数差分値Δｆｓｉｇを算出する。規格化周波数差分値Δｆｓｉｇは次式から得られる。
　Ｉｆ　Ｍｏｄ（Ｄｆ）≧５００　［Ｈｚ］
　　　　　　　　Δｆｓｉｇ＝ＡＢＳ（Ｄｆ－１０００）
　Ｅｌｓｅ　Ｍｏｄ（Ｄｆ）＜５００　［Ｈｚ］
　　　　　　　　Δｆｓｉｇ＝Ｍｏｄ（Ｄｆ）
　このように算出されたサーチ周波数Ｆｓｉｇに対する規格化周波数差分値Δｆｓｉｇと、上述の第１閾値周波数Ｆｃとを比較する（Ｓ４０２）。 The frequency difference value Df is obtained from the following equation.
Df = (ABS (F sig −F B )) / 1000 [Hz]
Next, the frequency difference value is normalized so as to be a value between 0 Hz and 500 Hz, and a normalized frequency difference value Δf sig is calculated. The normalized frequency difference value Δf sig is obtained from the following equation.
If Mod (Df) ≧ 500 [Hz]
Δf sig = ABS (Df-1000)
Else Mod (Df) <500 [Hz]
Δf sig = Mod (Df)
The standardized frequency difference value Δf sig for the search frequency F sig calculated in this way is compared with the first threshold frequency Fc described above (S402).
　規格化周波数差分値Δｆｓｉｇが第１閾値周波数Ｆｃよりも低ければ（Ｓ４０２：Ｙｅｓ）、サーチ周波数Ｆｓｉｇは第１周波数区間ＡＲｃ内と判定し、サーチ周波数Ｆｓｉｇに対して積算時間Ｔｃを採用する（Ｓ４０４）。 If the normalized frequency difference value Δf sig is lower than the first threshold frequency Fc (S402: Yes), the search frequency F sig is determined to be within the first frequency interval ARc, and the integration time Tc is adopted for the search frequency F sig . (S404).
　規格化周波数差分値Δｆｓｉｇが第１閾値周波数Ｆｃ以上であれば（Ｓ４０２：Ｎｏ）、サーチ周波数Ｆｓｉｇに対する規格化周波数差分値Δｆｓｉｇと、上述の第２閾値周波数Ｆｎとを比較する（Ｓ４０３）。 If the normalized frequency difference value Δf sig is equal to or higher than the first threshold frequency Fc (S402: No), the normalized frequency difference value Δf sig with respect to the search frequency F sig is compared with the above-described second threshold frequency Fn (S403). ).
　規格化周波数差分値Δｆｓｉｇが第２閾値周波数Ｆｎよりも低ければ（Ｓ４０３：Ｙｅｓ）、サーチ周波数Ｆｓｉｇは第２周波数区間ＡＲｎ内と判定し、サーチ周波数Ｆｓｉｇに対して積算時間Ｔｎを採用する（Ｓ４０５）。 If the normalized frequency difference value Δf sig is lower than the second threshold frequency Fn (S403: Yes), the search frequency F sig is determined to be within the second frequency interval ARn, and the integration time Tn is adopted for the search frequency F sig . (S405).
　規格化周波数差分値Δｆｓｉｇが第２閾値周波数Ｆｎ以上であれば（Ｓ４０３：Ｎｏ）、サーチ周波数Ｆｓｉｇは第３周波数区間ＡＲｆ内と判定し、サーチ周波数Ｆｓｉｇに対して積算時間Ｔｆを採用する（Ｓ４０６）。 If the normalized frequency difference value Δf sig is greater than or equal to the second threshold frequency Fn (S403: No), the search frequency F sig is determined to be within the third frequency interval ARf, and the integration time Tf is adopted for the search frequency F sig . (S406).
　このようにして、クロスコリレーションのピーク周波数に対するサーチ周波数Ｆｓｉｇの離間具合に応じた積算値が設定される。 In this way, an integrated value corresponding to the degree of separation of the search frequency F sig with respect to the peak frequency of cross correlation is set.
　具体的に、上述のように、サーチ周波数をグループ毎に５０Ｈｚ間隔でシフトさせる場合には、各グループＧｒ１～Ｇｒ１８を代表するサーチ周波数Ｆｓｉｇ０１１，Ｆｓｉｇ０２１，Ｆｓｉｇ０３１，Ｆｓｉｇ０４１，Ｆｓｉｇ０５１，Ｆｓｉｇ０６１，Ｆｓｉｇ０７１，Ｆｓｉｇ０８１，Ｆｓｉｇ０９１，Ｆｓｉｇ１０１，Ｆｓｉｇ１１１，Ｆｓｉｇ１２１，Ｆｓｉｇ１３１，Ｆｓｉｇ１４１，Ｆｓｉｇ１５１，Ｆｓｉｇ１６１，Ｆｓｉｇ１７１，Ｆｓｉｇ１８１，Ｆｓｉｇ１９１は、図８のように設定される。図８は周波数区間の判定概念および積算時間の設定概念を説明するための図である。なお、図８では、各グループＧｒ１のサーチ周波数Ｆｓｉｇ０１１が、クロスコリレーションのピーク周波数から最も遠い例を示している。 Specifically, as described above, when the search frequency is shifted at 50 Hz intervals for each group, the search frequencies F sig 011, F sig 021, F sig 031, F sig 041, which represent the groups Gr 1 to Gr 18. F sig 051, F sig 061, F sig 071, F sig 081, F sig 091, F sig 101, F sig 111, F sig 121, F sig 131, F sig 141, F sig 151, F sig 161, F sig 171, F sig 181 and F sig 191 are set as shown in FIG. 8. FIG. 8 is a diagram for explaining the determination concept of the frequency section and the setting concept of the integration time. FIG. 8 shows an example in which the search frequency F sig 011 of each group Gr1 is farthest from the peak frequency of cross correlation .
　図８の例では、サーチ周波数Ｆｓｉｇ０１１，Ｆｓｉｇ０２１，Ｆｓｉｇ０３１，Ｆｓｉｇ０４１，Ｆｓｉｇ０５１，Ｆｓｉｇ０６１は第３周波数区間ＡＲｆに該当する。サーチ周波数Ｆｓｉｇ０７１，Ｆｓｉｇ０８１は第２周波数区間ＡＲｎに該当する。サーチ周波数Ｆｓｉｇ０９１，Ｆｓｉｇ１０１，Ｆｓｉｇ１１１は第１周波数区間ＡＲｃに該当する。サーチ周波数Ｆｓｉｇ１２１，Ｆｓｉｇ１３１は第２周波数区間ＡＲｎに該当する。サーチ周波数Ｆｓｉｇ１４１，Ｆｓｉｇ１５１，Ｆｓｉｇ１６１，Ｆｓｉｇ１７１，Ｆｓｉｇ１８１，Ｆｓｉｇ１９１は第３周波数区間ＡＲｆに該当する。 In the example of FIG. 8, the search frequencies F sig 011, F sig 021, F sig 031, F sig 041, F sig 051, and F sig 061 correspond to the third frequency interval ARf. The search frequencies F sig 071 and F sig 081 correspond to the second frequency interval ARn. The search frequencies F sig 091, F sig 101, and F sig 111 correspond to the first frequency interval ARc. The search frequencies F sig 121 and F sig 131 correspond to the second frequency interval ARn. The search frequencies F sig 141, F sig 151, F sig 161, F sig 171, F sig 181, and F sig 191 correspond to the third frequency interval ARf.
　したがって、サーチ周波数Ｆｓｉｇ０１１，Ｆｓｉｇ０２１，Ｆｓｉｇ０３１，Ｆｓｉｇ０４１，Ｆｓｉｇ０５１，Ｆｓｉｇ０６１、およびサーチ周波数Ｆｓｉｇ１４１，Ｆｓｉｇ１５１，Ｆｓｉｇ１６１，Ｆｓｉｇ１７１，Ｆｓｉｇ１８１，Ｆｓｉｇ１９１には、積算時間Ｔｆが採用される。サーチ周波数Ｆｓｉｇ０７１，Ｆｓｉｇ０８１およびサーチ周波数Ｆｓｉｇ１２１，Ｆｓｉｇ１３１には、積算時間Ｔｎが採用される。サーチ周波数Ｆｓｉｇ０９１，Ｆｓｉｇ１０１，Ｆｓｉｇ１１１には積算時間Ｔｃが採用される。 Therefore, the search frequencies F sig 011, F sig 021, F sig 031, F sig 041, F sig 051, F sig 061, and the search frequencies F sig 141, F sig 151, F sig 161, F sig 171, F sig 181 , F sig 191 employs the integration time Tf. For the search frequencies F sig 071 and F sig 081 and the search frequencies F sig 121 and F sig 131, the integration time Tn is adopted. For the search frequencies F sig 091, F sig 101, and F sig 111, the integration time Tc is adopted.
　このように設定された積算時間に応じて、各サーチ周波数で相関処理が行われ、積算時間に応じた積算相関値が算出される。 Correlation processing is performed at each search frequency according to the integration time set in this way, and an integration correlation value corresponding to the integration time is calculated.
　この積算時間を設定して積算相関値を出力する処理は、周波数帯域の全域に亘るまで、継続的に実行される（Ｓ１０７：Ｎｏ→Ｓ１０５）。そして、周波数帯域の全域での積算相関値が算出されると（Ｓ１０７：Ｙｅｓ）、各コード位相、周波数での積算相関値に基づいて、ＧＰＳ信号を捕捉する（Ｓ１０８）。具体的には、積算相関値が所定閾値以上のコード位相、周波数を検出し、このタイミングをＧＰＳ信号の捕捉タイミングとする。なお、この際、周波数区間によって積算時間が異なるため、周波数区間毎に閾値を補正してもよい。また、周波数区間毎に積算相関値を補正してもよい。 The process of setting the integration time and outputting the integration correlation value is continuously executed until the entire frequency band is covered (S107: No → S105). When the integrated correlation value in the entire frequency band is calculated (S107: Yes), a GPS signal is captured based on the integrated correlation value in each code phase and frequency (S108). Specifically, a code phase and frequency whose integrated correlation value is greater than or equal to a predetermined threshold are detected, and this timing is used as a GPS signal capture timing. At this time, since the integration time varies depending on the frequency section, the threshold value may be corrected for each frequency section. Further, the integrated correlation value may be corrected for each frequency section.
　このような処理を行うことで、上述のように、周波数区間に応じて適切にクロスコリレーションの影響が低減され、信号サーチ性能を従来方法よりも向上させることができる。 By performing such processing, as described above, the influence of cross-correlation is appropriately reduced according to the frequency section, and the signal search performance can be improved as compared with the conventional method.
　また、クロスコリレーションの影響を受けにくい第２、第３周波数区間ＡＲｎ，ＡＲｆの積算時間Ｔｎ，Ｔｆを、クロスコリレーションの影響を受けやすい第１周波数区間の積算時間Ｔｃよりも短くすることで、全周波数帯域において、クロスコリレーションの影響を受けやすい第１周波数区間の積算時間Ｔｃを採用するよりも、１チャンネル分の信号サーチ時間を短縮することができる。 Further, the integration times Tn and Tf of the second and third frequency sections ARn and ARf that are not easily affected by cross-correlation are made shorter than the integration time Tc of the first frequency section that is easily affected by cross-correlation. In the entire frequency band, the signal search time for one channel can be shortened compared with the case where the integration time Tc of the first frequency section that is easily affected by cross-correlation is employed.
　以上のように、本実施形態の信号サーチ方法を用いれば、クロスコリレーションによる誤捕捉を生じることなく、従来方法よりも短時間でＧＰＳ信号の捕捉を行うことができる。 As described above, by using the signal search method of this embodiment, GPS signals can be captured in a shorter time than the conventional method without causing erroneous capture due to cross-correlation.
　なお、上述の説明では、カウント数に応じて積算時間Ｔｃ，Ｔｎ，Ｔｆを設定する例を示したが、カウント数を考慮することなく、周波数区間毎に、クロスコリレーションのピーク周波数に近い順に、積算時間を長くするようにしてもよい。このような積算時間の設定を行えば、予備サーチを必要としない。ただし、カウント数に応じて積算時間を設定する場合には、予備検出信号が無い場合に第２周波数区間ＡＲｎの積算時間Ｔｎ、および第３周波数区間ＡＲｆの積算時間Ｔｆを同等に短くしたり、各積算時間を一様に短くする等の設定が可能になり、状況に応じて、より最適な積算時間の設定が可能になる。 In the above description, the example in which the integration times Tc, Tn, and Tf are set according to the number of counts has been shown. However, without considering the number of counts, the frequency closer to the cross-correlation peak frequency for each frequency interval. The integration time may be lengthened. If such integration time is set, a preliminary search is not required. However, when the integration time is set according to the count number, the integration time Tn of the second frequency section ARn and the integration time Tf of the third frequency section ARf are equally shortened when there is no preliminary detection signal, Settings such as uniformly shortening each accumulated time are possible, and a more optimal accumulated time can be set according to the situation.
　また、上述の説明では、クロスコリレーションのピーク周波数からの離間量のみに応じて、積算時間を設定する例を示したが、予備検出信号の信号強度も用いて積算時間を設定してもよい。図９は信号強度区分の設定概念を説明するための図である。図１０は信号強度区分も含めた積算時間設定用マップの一例を示す図である。 In the above description, the example in which the integration time is set according to only the distance from the peak frequency of the cross-correlation is shown. However, the integration time may be set using the signal intensity of the preliminary detection signal. . FIG. 9 is a diagram for explaining the concept of setting signal strength categories. FIG. 10 is a diagram showing an example of an integration time setting map including a signal intensity category.
　図９に示すように、信号強度区分は、予備検出信号のＣ／Ｎｏに応じて、３段階に設定されている。具体的には、第１閾値Ｃ／Ｎ０ｎ未満を第１信号強度区分ＺＯＮＥｗに設定し、第１閾値Ｃ／Ｎ０ｎ以上第２閾値Ｃ／Ｎ０ｓ未満を第２信号強度区分ＺＯＮＥｎに設定し、第２閾値Ｃ／Ｎ０ｓ以上を第３信号強度区分ＺＯＮＥｓに設定する。 As shown in FIG. 9, the signal intensity classification is set in three stages according to the C / No of the preliminary detection signal. Specifically, the first threshold value C / N0n is set to the first signal strength section ZONEw, the first threshold value C / N0n to the second threshold value C / N0s is set to the second signal strength section ZONEw, The threshold value C / N0s or more is set in the third signal strength category ZONEs.
　予備検出信号を取得した場合、予備検出信号毎にＣ／Ｎ０を検出し、いずれの信号強度区分に該当するか判定する。 When a preliminary detection signal is acquired, C / N0 is detected for each preliminary detection signal, and it is determined which signal intensity category is applicable.
　この処理を行うことで、上述の周波数区間の判定結果とともに、図１０に示すような積算時間設定用マップを形成することができる。 By performing this process, an integrated time setting map as shown in FIG. 10 can be formed together with the determination result of the frequency section described above.
　そして、各周波数区間において、各信号強度区分に該当する予備検出信号数の分布を参照して、各周波数区間の積算時間を設定する。例えば、図１０に示すように、第１周波数区間ＡＲｃに、Ｃ／Ｎ０の高い予備検出信号が存在すると判明すれば、当該予備検出信号はクロスコリレーションによるピーク周波数を発生する追尾中のＧＰＳ信号である可能性が高いので、当該追尾中のＧＰＳ信号の影響を受けにくくするように、積算時間を、より長く補正すればよい。 Then, in each frequency section, the accumulated time of each frequency section is set with reference to the distribution of the number of preliminary detection signals corresponding to each signal intensity category. For example, as shown in FIG. 10, if it is determined that a preliminary detection signal having a high C / N0 exists in the first frequency interval ARc, the preliminary detection signal is a GPS signal being tracked that generates a peak frequency due to cross-correlation. Therefore, the accumulated time may be corrected to be longer so that it is less affected by the GPS signal being tracked.
　これにより、さらに受信状況に応じて、より適する積算時間を設定でき、クロスコリレーションによる誤捕捉をさらに生じないようにすることができる。 This makes it possible to set a more appropriate integration time according to the reception status, and to prevent further erroneous capture due to cross-correlation.
　以上のような処理は、次に示す構成のＧＰＳ信号受信装置で実現できる。図１１は、本発明の実施形態に係るＧＰＳ信号受信装置１の構成を示すブロック図である。 The above processing can be realized by a GPS signal receiving apparatus having the following configuration. FIG. 11 is a block diagram showing a configuration of the GPS signal receiving apparatus 1 according to the embodiment of the present invention.
　ＧＰＳ信号受信装置１は、ＧＰＳ受信アンテナ１０、ＲＦ処理部２０、ベースバンド処理部３０、および測位演算部４０を備える。 The GPS signal receiving device 1 includes a GPS receiving antenna 10, an RF processing unit 20, a baseband processing unit 30, and a positioning calculation unit 40.
　ＧＰＳ受信アンテナ１０は、各ＧＰＳ衛星から放送（送信）されるＧＰＳ信号を受信し、ＲＦ処理部２０へ出力する。ＲＦ処理部２０は、受信したＧＰＳ信号をダウンコンバートして、中間周波数信号（ＩＦ信号）生成し、ベースバンド処理部３０へ出力する。 The GPS receiving antenna 10 receives a GPS signal broadcast (transmitted) from each GPS satellite and outputs it to the RF processing unit 20. The RF processing unit 20 down-converts the received GPS signal, generates an intermediate frequency signal (IF signal), and outputs it to the baseband processing unit 30.
　ベースバンド処理部３０は、本発明の「積算時間決定部」および「相関値算出部」を備える「信号サーチ装置」に対応する。また、ベースバンド処理部３０は、本発明の「捕捉追尾部」にも対応する。なお、ベースバンド処理部３０は、「積算時間決定部」に相当するハードウェアと、「相関値算出部」および「捕捉追尾部」に相当するハードウェアとを個別に実現してもよく、一体のハードウェアで実現してもよい。ベースバンド処理部３０は、ＩＦ信号にキャリア周波数信号を乗算することでベースバンド信号を生成し、当該ベースバンド信号によるＧＰＳ信号の捕捉処理、および追尾処理を行う。この際、捕捉処理に、上述の信号サーチ方法を用いる。これにより、クロスコリレーションの誤捕捉を抑制し、目的とするＧＰＳ信号を確実に捕捉できる。 The baseband processing unit 30 corresponds to a “signal search device” including the “integrated time determining unit” and the “correlation value calculating unit” of the present invention. The baseband processing unit 30 also corresponds to the “capture tracking unit” of the present invention. Note that the baseband processing unit 30 may individually implement hardware corresponding to the “integration time determination unit” and hardware corresponding to the “correlation value calculation unit” and the “capture tracking unit”. You may implement | achieve with the hardware of. The baseband processing unit 30 generates a baseband signal by multiplying the IF signal by the carrier frequency signal, and performs a GPS signal capturing process and a tracking process using the baseband signal. At this time, the signal search method described above is used for the acquisition process. Thereby, the erroneous capture of cross-correlation can be suppressed and the target GPS signal can be reliably captured.
　このような捕捉されたＧＰＳ信号に対する捕捉処理は、追尾処理に移行する。この追尾に得られるコード相関結果やキャリア相関結果、さらにはコード相関結果から得られる擬似距離は、測位演算部４０へ出力される。 The capturing process for such a captured GPS signal shifts to a tracking process. The code correlation result and carrier correlation result obtained by the tracking, and the pseudo distance obtained from the code correlation result are output to the positioning calculation unit 40.
　測位演算部４０は、コード相関結果に基づいて航法メッセージを復調するとともに、コード相関結果、キャリア位相結果、擬似距離から、ＧＰＳ信号受信装置１の測位を行う。 The positioning calculation unit 40 demodulates the navigation message based on the code correlation result, and performs positioning of the GPS signal receiving device 1 from the code correlation result, the carrier phase result, and the pseudorange.
　このような構成を用い、上述の信号サーチ方法を用いることで、誤捕捉が抑制され且つ高速な捕捉を行えるので、ＧＰＳ信号の追尾精度が向上し、結果的に測位結果の精度を向上させることもできる。 By using such a configuration and using the above-described signal search method, erroneous acquisition is suppressed and high-speed acquisition can be performed, so that the tracking accuracy of GPS signals is improved, and as a result, the accuracy of positioning results is improved. You can also.
　なお、上述の信号サーチ方法を実行するベースバンド処理部３０は、各処理を実行するハードウェア群で実現してもよく、上述の信号サーチ方法の各処理をプログラム化した状態で記憶媒体に記憶しておき、コンピュータで当該プログラムを読み出して実行する態様によって実現してもよい。 Note that the baseband processing unit 30 that executes the above-described signal search method may be realized by a hardware group that executes each process, and stores each process of the above-described signal search method in a storage medium in a programmed state. In addition, it may be realized by a mode in which the computer reads and executes the program.
　また、このようなＧＰＳ信号受信装置１やＧＰＳ信号受信機能は、図１２に示すような情報機器端末１００に利用される。図１２は、本実施形態のＧＰＳ信号受信装置１を備えた情報機器端末１００の主要構成を示すブロック図である。 Further, such a GPS signal receiving device 1 and a GPS signal receiving function are used for an information equipment terminal 100 as shown in FIG. FIG. 12 is a block diagram illustrating a main configuration of the information equipment terminal 100 including the GPS signal receiving device 1 of the present embodiment.
　図１２に示すような情報機器端末１００は、例えば携帯電話機、カーナビゲーション装置、ＰＮＤ、カメラ、時計等であり、アンテナ１０、ＲＦ処理部２０、ベースバンド処理部３０、測位演算部４０、アプリケーション処理部１３０を備える。アンテナ１０、ＲＦ処理部２０、ベースバンド処理部３０、測位演算部４０は、上述の構成のものであり、これらにより上述のようにＧＰＳ信号受信装置１が構成されている。 An information equipment terminal 100 as shown in FIG. 12 is, for example, a mobile phone, a car navigation device, a PND, a camera, a clock, and the like, and includes an antenna 10, an RF processing unit 20, a baseband processing unit 30, a positioning calculation unit 40, and application processing. Part 130 is provided. The antenna 10, the RF processing unit 20, the baseband processing unit 30, and the positioning calculation unit 40 have the above-described configuration, and the GPS signal receiving device 1 is configured as described above.
　アプリケーション処理部１３０は、ＧＰＳ信号受信装置１から出力された測位結果に基づいて、自装置位置や自装置速度を表示したり、ナビゲーション等に利用するための処理を実行する。 The application processing unit 130 displays the own device position and the own device speed based on the positioning result output from the GPS signal receiving device 1, and executes processing for use in navigation and the like.
　このような構成において、上述のように高精度な測位結果を得られることで、高精度な位置表示やナビゲーション等を実現することができる。 In such a configuration, highly accurate positioning results and navigation can be realized by obtaining highly accurate positioning results as described above.
　なお、上述の説明では、ＧＰＳ信号のクロスコリレーションの場合を例に説明したが、他のＧＮＳＳ信号の捕捉にも同様に適用できる。さらには、所定周波数間隔で相関値にピークが現れるような無線通信信号の捕捉に対しても、同様に適用できる。 In the above description, the case of cross-correlation of GPS signals has been described as an example, but the present invention can be similarly applied to capturing other GNSS signals. Furthermore, the present invention can be similarly applied to capturing a wireless communication signal in which a peak appears in a correlation value at a predetermined frequency interval.
　また、上述の周波数区間の設定処理では、３個の周波数区間を設定する例を示したが、２個以上の周波数区間に設定することができる。同様に、信号強度区分も、２個以上の信号強度区分に設定することができる。 In the above-described frequency section setting process, an example in which three frequency sections are set is shown. However, two or more frequency sections can be set. Similarly, the signal strength section can be set to two or more signal strength sections.
　また、上述の説明では、詳細に示していないが、積算時間はコヒーレント積算時間、ノンコヒーレント積算時間のうち、いずれか一方か、もしくは両方を設定変更することで、積算時間の補正を実現すればよい。 Although not shown in detail in the above description, the integration time can be corrected by setting or changing either one or both of the coherent integration time and the non-coherent integration time. Good.
　また、上述の説明では、サーチ対象周波数Ｆｓｉｇを複数の周波数区間に振り分け、周波数区間毎に積算時間を設定する例を示したが、サーチ対象周波数Ｆｓｉｇと追尾中のＧＰＳ信号の周波数ＦＢとの周波数差分値に応じて、サーチ対象周波数Ｆｓｉｇ毎に、積算時間を設定することも可能である。この場合、例えば、サーチ対象周波数Ｆｓｉｇと追尾中のＧＰＳ信号の周波数ＦＢと周波数差分値が大きくなるほど、積算時間を短くなるように設定すればよい。 In the above description, the search target frequency F sig is divided into a plurality of frequency sections, and the integration time is set for each frequency section. However, the search target frequency F sig and the frequency F B of the GPS signal being tracked are shown. It is also possible to set the integration time for each search target frequency F sig according to the frequency difference value. In this case, for example, the frequency F B and the frequency difference value is larger in the GPS signal in the tracking and search target frequency F sig, it may be set to be shorter integration time.
１：ＧＰＳ信号受信装置、１０：ＧＰＳ受信アンテナ、２０：ＲＦ処理部、３０：ベースバンド処理部、４０：測位演算部、１００：情報機器端末、１３０：アプリケーション処理部 1: GPS signal receiving device, 10: GPS receiving antenna, 20: RF processing unit, 30: baseband processing unit, 40: positioning calculation unit, 100: information equipment terminal, 130: application processing unit

Claims (15)

  1. 　目的の信号を捕捉するための信号サーチ方法であって、
    　追尾中の信号の周波数とサーチ対象の周波数との周波数差に応じて、該サーチ対象の周波数での積算時間を設定する積算時間決定工程と、
    　前記目的の信号のレプリカ信号と受信信号との相関値を算出する相関値算出工程と、
    　設定された積算時間で前記相関値を積算することにより積算相関値を算出する積算相関値算出工程と、
    　を有する信号サーチ方法。     A signal search method for acquiring a target signal,
    An integration time determination step of setting an integration time at the frequency of the search target according to a frequency difference between the frequency of the signal being tracked and the frequency of the search target;
    A correlation value calculating step of calculating a correlation value between the replica signal of the target signal and the received signal;
    An integrated correlation value calculating step of calculating an integrated correlation value by integrating the correlation value for a set integration time;
    A signal search method comprising:
  2. 　請求項１に記載の信号サーチ方法であって、
    　前記積算時間決定工程は、
    　追尾中の信号の周波数とサーチ対象の周波数との周波数差に応じて、前記サーチ対象の周波数が選択的に該当し得る複数の周波数区間を決定する周波数区間決定工程と、
    　前記サーチ対象の周波数が前記複数の周波数区間のいずれに属するかを判定する区分判定工程と、
    　前記周波数区間毎に積算時間を設定する決定工程と、
    　を有する信号サーチ方法。     The signal search method according to claim 1,
    The accumulated time determination step includes
    A frequency interval determining step for determining a plurality of frequency intervals in which the search target frequency can selectively correspond according to a frequency difference between the frequency of the signal being tracked and the frequency of the search target;
    A classification determination step for determining which of the plurality of frequency sections the frequency to be searched belongs to;
    A determination step of setting an integration time for each frequency section;
    A signal search method comprising:
  3. 　請求項２に記載の信号サーチ方法であって、
    　前記周波数区間決定工程は、
    　前記追尾中の信号により前記積算相関値の算出時に現れる相関ピークとなる周波数の繰り返し間隔に基づいて、前記複数の周波数区間を設定する工程を有し、
    　前記区分判定工程は、
    　前記サーチ対象の周波数と、前記追尾中の信号の周波数との周波数差分値を算出する工程と、
    　前記周波数差分値が前記複数の周波数区間のいずれの範囲内にあるかを判定する工程と、を有する、信号サーチ方法。     The signal search method according to claim 2,
    The frequency interval determination step includes
    A step of setting the plurality of frequency sections based on a frequency repetition interval that becomes a correlation peak that appears when the integrated correlation value is calculated by the signal being tracked;
    The category determination step includes
    Calculating a frequency difference value between the frequency to be searched and the frequency of the signal being tracked;
    Determining which range of the plurality of frequency sections the frequency difference value falls within.
  4. 　請求項３に記載の信号サーチ方法であって、
    　前記積算時間決定工程は、
    　予め行った予備サーチにより検出された予備検出信号の周波数が前記複数の周波数区間のそれぞれに属する数を検出する工程と、
    　前記周波数区間に属する予備検出信号の数に応じて前記積算時間を補正する工程と、
    　を有する信号サーチ方法。     The signal search method according to claim 3, comprising:
    The accumulated time determination step includes
    Detecting the number of frequencies of a preliminary detection signal detected by a preliminary search performed in advance belonging to each of the plurality of frequency sections;
    Correcting the integration time according to the number of preliminary detection signals belonging to the frequency interval;
    A signal search method comprising:
  5. 　請求項４に記載の信号サーチ方法であって、
    　前記積算時間決定工程は、
    　前記予備検出信号の信号強度を検出する工程と、
    　前記予備検出信号の信号強度が、予め設定された複数の信号強度区分のそれぞれに属する数を検出する工程と、
    　前記信号強度区分毎に属する前記予備検出信号の数の分布に応じて前記積算時間をさらに補正する工程と、
    　を有する信号サーチ方法。     The signal search method according to claim 4,
    The accumulated time determination step includes
    Detecting the signal strength of the preliminary detection signal;
    Detecting the number of signal strengths of the preliminary detection signal belonging to each of a plurality of preset signal strength categories;
    Further correcting the integration time according to the distribution of the number of preliminary detection signals belonging to each signal strength category;
    A signal search method comprising:
  6. 　請求項３乃至請求項５のいずれかに記載の信号サーチ方法であって、
    　前記サーチ対象の周波数を、繰り返し間隔と同じ離間間隔で複数設定する工程を有し、
    　複数のサーチ対象の周波数で平行して、前記相関値算出工程を実行する、信号サーチ方法。     A signal search method according to any one of claims 3 to 5,
    A step of setting a plurality of frequencies to be searched at the same separation interval as the repetition interval;
    A signal search method, wherein the correlation value calculating step is executed in parallel at a plurality of search target frequencies.
  7. 　請求項１乃至請求項６のいずれかに記載の信号サーチ方法であって、
    　前記目的の信号は、ＧＰＳ衛星毎に放送されるＧＰＳ信号である、信号サーチ方法。     A signal search method according to any one of claims 1 to 6,
    The signal search method, wherein the target signal is a GPS signal broadcast for each GPS satellite.
  8. 　目的の信号を捕捉するための信号サーチ処理をコンピュータに実行させる信号サーチプログラムであって、
    　追尾中の信号の周波数とサーチ対象の周波数との周波数差に応じて、該サーチ対象の周波数での積算時間を設定する積算時間決定処理と、
    　前記目的の信号のレプリカ信号と受信信号との相関値を算出する相関値算出処理と、
    　設定された積算時間で前記相関値を積算することにより積算相関値を算出する積算相関値算出処理と、
    　を含む信号サーチプログラム。     A signal search program for causing a computer to execute a signal search process for capturing a target signal,
    An integration time determination process for setting an integration time at the frequency to be searched according to the frequency difference between the frequency of the signal being tracked and the frequency to be searched;
    A correlation value calculation process for calculating a correlation value between the replica signal of the target signal and the received signal;
    An integrated correlation value calculation process for calculating an integrated correlation value by integrating the correlation values for a set integration time;
    Signal search program including
  9. 　請求項８に記載の信号サーチプログラムであって、
    　前記積算時間決定処理には、
    　追尾中の信号の周波数とサーチ対象の周波数との周波数差に応じて、前記サーチ対象の周波数が選択的に該当し得る複数の周波数区間を決定する周波数区間決定処理と、
    　前記１つのサーチ対象の周波数が前記複数の周波数区間のいずれに属するかを判定する区分判定処理と、
    　前記周波数区間毎に積算時間を設定する決定処理と、
    　を含む信号サーチプログラム。     The signal search program according to claim 8,
    In the accumulated time determination process,
    A frequency interval determination process for determining a plurality of frequency intervals in which the search target frequency can selectively correspond according to the frequency difference between the frequency of the signal being tracked and the frequency of the search target;
    A classification determination process for determining which of the plurality of frequency sections the one search target frequency belongs to;
    A determination process for setting an integration time for each frequency section;
    Signal search program including
  10. 　請求項９に記載の信号サーチプログラムであって、
    　前記周波数区間決定処理には、
    　前記追尾中の信号により前記積算相関値の算出時に現れる相関ピークとなる周波数の繰り返し間隔に基づいて、前記複数の周波数区間を設定する処理を含み、
    　前記区分判定処理には、
    　前記サーチ対象の周波数と、前記追尾中の信号の周波数との周波数差分値を算出する処理と、
    　前記周波数差分値が前記複数の周波数区間のいずれの範囲内にあるかを判定する処理と、を含む、信号サーチプログラム。     The signal search program according to claim 9,
    In the frequency interval determination process,
    Including a process of setting the plurality of frequency sections based on a frequency repetition interval that becomes a correlation peak that appears when the integrated correlation value is calculated by the signal being tracked,
    In the classification determination process,
    Processing for calculating a frequency difference value between the frequency to be searched and the frequency of the signal being tracked;
    And a process of determining which of the plurality of frequency sections the frequency difference value falls within.
  11. 　目的の信号を捕捉するための信号サーチ装置であって、
    　追尾中の信号の周波数とサーチ対象の周波数との周波数差に応じて、該サーチ対象の周波数での積算時間を設定する積算時間決定部と、
    　前記目的の信号のレプリカ信号と受信信号との相関値を算出し、設定された積算時間で前記相関値を積算することにより積算相関値を算出する相関値算出部と、
    　を含む信号サーチ装置。     A signal search device for capturing a target signal,
    An integration time determination unit that sets an integration time at the frequency of the search target according to a frequency difference between the frequency of the signal being tracked and the frequency of the search target;
    A correlation value calculating unit that calculates a correlation value between the replica signal of the target signal and the received signal, and calculates an integrated correlation value by integrating the correlation value at a set integration time;
    A signal search device including:
  12. 　請求項１１に記載の信号サーチ装置であって、
    　前記積算時間決定部は、
    　追尾中の信号の周波数とサーチ対象の周波数との周波数差に応じて、前記サーチ対象の周波数が選択的に該当し得る複数の周波数区間を決定し、前記１つのサーチ対象の周波数が前記複数の周波数区間のいずれに属するかを判定し、前記周波数区間毎に前記サーチ対象の周波数に対する積算時間を設定する、信号サーチ装置。     The signal search device according to claim 11,
    The accumulated time determination unit
    According to the frequency difference between the frequency of the signal being tracked and the frequency of the search target, a plurality of frequency sections in which the search target frequency can be selectively applied are determined, and the frequency of the single search target is the plurality of the search target frequencies. A signal search device that determines which of the frequency sections belongs and sets an integration time for the frequency to be searched for each frequency section.
  13. 　請求項１２に記載の信号サーチ装置であって、
    　前記積算時間決定部は、前記追尾中の信号により前記積算相関値の算出時に現れる相関ピークとなる周波数の繰り返し間隔に基づいて前記複数の周波数区間を設定し、前記サーチ対象の周波数と前記追尾中の信号の周波数との周波数差分値を算出し、前記周波数差分値が前記複数の周波数区間のいずれの範囲内にあるかを判定する、信号サーチ装置。     The signal search device according to claim 12, wherein
    The integration time determination unit sets the plurality of frequency intervals based on a frequency repetition interval that becomes a correlation peak that appears when the integration correlation value is calculated based on the signal being tracked, and sets the frequency to be searched and the tracking target frequency. A signal search device that calculates a frequency difference value with respect to the frequency of the signal and determines in which of the plurality of frequency sections the frequency difference value is.
  14. 　請求項１１乃至請求項１３のいずれかに記載の信号サーチ装置と、
    　前記積算相関値から前記目的の信号を捕捉、追尾する捕捉追尾部と、
    　追尾結果に基づいて測位を行う測位演算部と、を備えるＧＮＳＳ信号受信装置。     A signal search device according to any one of claims 11 to 13,
    A capture tracking unit that captures and tracks the target signal from the integrated correlation value;
    A GNSS signal receiving apparatus comprising: a positioning calculation unit that performs positioning based on a tracking result.
  15. 　請求項１４に記載のＧＮＳＳ信号受信装置と、
    　前記測位演算部の測位演算結果を用いて所定のアプリケーションを実行するアプリケーション処理部と、を備える情報機器端末。     GNSS signal receiving device according to claim 14,
    An information processing device terminal comprising: an application processing unit that executes a predetermined application using a positioning calculation result of the positioning calculation unit.
PCT/JP2013/053888 2012-03-22 2013-02-18 Signal search method, signal search program, signal search device, global navigation satellite system (gnss) signal receiver, and information terminal WO2013140909A1 (en)

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