JP2008122120A - Sps receiver and mobile communication terminal apparatus with sps receiving function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly reacquire satellite radio waves in an SPS receiver when a reception of the satellite radio waves is interrupted. <P>SOLUTION: The SPS receiver is provided with: a trigger detecting means for detecting a condition change in the SPS receiver as a trigger for changing a search range of an SPS reception frequency; and a search range correcting/controlling means for changing the search range of the SPS reception frequency. When the predetermined condition change in the SPS receiver is detected by the trigger detecting means, the search range correcting/controlling means expands or reduces the search range of the SPS reception frequency, and receives the satellite radio waves. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an SPS receiver that quickly captures satellite radio waves and a mobile communication terminal with an SPS reception function.

  In recent years, mobile navigation devices equipped with SPS receivers of satellite positioning systems (hereinafter referred to as SPS) represented by GPS (Global Positioning System) and mobile devices with SPS reception functions such as mobile phone devices with SPS reception functions. Communication terminal devices have been put into practical use. In order to perform accurate positioning with high accuracy, these mobile communication terminal devices require that the on-board SPS receiver stably receive radio waves transmitted by artificial satellites. For this reason, when the SPS receiver is blocked by a building or a tunnel and the radio wave of the artificial satellite that has been captured until then cannot be received, it is devised so that the satellite radio wave can be quickly captured.

  For example, in a GPS receiver that is one of the conventional SPS receivers, when the radio wave of a captured satellite becomes unreceivable for a certain period of time or more, the reception frequency of the satellite radio wave at the time when the radio wave becomes impossible is centered. As a frequency, it has been proposed to search while gradually expanding the PLL search frequency over a wide band each time the search is repeated. As a result, it is possible to recapture satellite radio waves faster than searching for satellite radio waves while swinging the search frequency from the beginning over a wide range of the maximum change range of the reception frequency of satellite radio waves (for example, patents). Reference 1).

In another conventional GPS receiver, when the GPS receiver itself is moving, the satellite radio wave may be searched while changing the search frequency within the range of the change of the Doppler frequency due to the moving speed of the GPS receiver. Proposed. By searching for the moving speed of the GPS receiver, the satellite radio wave can be recaptured earlier even when the GPS receiver itself is moving (see, for example, Patent Document 2). .
JP-A-3-181875 (3rd page, FIG. 1) Japanese Patent Laid-Open No. 3-29377 (page 4, FIG. 1)

  However, the situation where the SPS receiver is placed changes every moment. If the situation change is large, the apparent reception frequency of the satellite radio wave to be searched changes. Originally, it is expected that the SPS reception frequency range to be searched according to the new situation, that is, the search range is quickly reset, and the search is expected, but no appropriate countermeasure has been taken.

  As an example, a case where a conventional GPS receiver is mounted on an automobile and passes through a tunnel will be described. FIG. 10A shows a change in search frequency, and FIG. 10B shows a running state of the automobile. The vertical axis in FIG. 10A is the frequency, the horizontal axis is the time axis, and the relationship between the transition of the search range centered on the search reference frequency (fs) and the frequency (fo) of the transmitted satellite wave is shown. Show. In addition, the vertical axis in FIG. 10B is the traveling speed of the automobile, the horizontal axis is the time axis, and the transition of the traveling speed when the automobile exits the tunnel is shown as an example. When the automobile enters the tunnel, the satellite radio wave cannot be received by the GPS receiver as shown in FIG. If the satellite radio wave cannot be received for a predetermined time, the search is performed in the narrow search range in the vicinity, that is, the range indicated by “F1” in FIG. 10A, using the reception frequency acquired immediately before as the search reference frequency (fs). . Each time the search is repeated, the search range is gradually expanded from the narrow search range (F1) to the wide search range (F5). However, as shown in FIG. 10B, the automobile travels at a relatively low speed (VL) in order to travel safely in the tunnel, and suddenly accelerates after moving through the tunnel to shift to high speed travel (VH). When the vehicle moves to high speed in this way, the apparent reception frequency of satellite radio waves changes as indicated by fa, so it is preferable to rapidly expand the search range. However, in the conventional GPS receiver, since a series of search operations for gradually expanding the search range is continued, the trigger associated with the shift to the high-speed traveling is not applied, and the satellite radio wave is hardly generated in the narrow search range. There was a problem that the state that could not be captured continued.

  An object of the present invention is to solve the above-described conventional problems and to provide an SPS receiving device and a mobile communication terminal device with an SPS receiving function capable of quickly capturing satellite radio waves even when the situation changes. .

  In order to solve the above-described conventional problems, the present invention provides a trigger detection means for detecting, as a trigger, a status change in which the SPS receiver is placed in the SPS receiver, and a search range for changing the search range of the SPS reception frequency. A correction control means is provided, and when a predetermined change in situation is detected as a situation where the SPS receiver is placed by the trigger detection means, the search range correction control means expands or reduces the search range of the SPS reception frequency. It is configured to receive radio waves from satellites.

  With this configuration, in response to changes in the situation where the SPS receiver is placed, the search range of the SPS reception frequency is expanded to increase the possibility of receiving satellite radio waves, or the search range of the SPS reception frequency is specified. By reducing the range to a specific range, the frequency of searching within a specific range within a predetermined time is increased to increase the possibility of receiving satellite radio waves, and satellite radio waves can be quickly captured.

  According to the SPS receiving device and the mobile communication terminal device with the SPS receiving function of the present invention, when a satellite radio wave is not captured within a predetermined time at a frequency within a predetermined search range, the SPS reception frequency search is triggered by that. There is an effect that satellite radio waves can be quickly captured at a search frequency in a new range by switching the range.

  Further, in the present invention, when the SPS receiver and the mobile communication terminal device with an SPS reception function start moving at a high speed, or when the movement has stopped at a high speed, the situation changes immediately. As a result, the SPS reception frequency search range can be switched to quickly capture satellite radio waves within the new search range.

(Embodiment 1)
FIG. 1 shows a block diagram of a GPS receiver according to Embodiment 1 of the present invention. As shown in FIG. 1, the GPS receiver 100 includes a GPS antenna 101 that receives satellite radio waves, a GPS receiver 102, and a GPS clock source 103, and uses the clock from the GPS clock source 103 to receive the GPS receiver 102. Is operating. The GPS receiving means 102 performs a satellite search on the GPS satellite radio wave input from the GPS antenna based on the search frequency and search range set by the search control means 104 described later, and performs code synchronization. The GPS receiving means 102 has a plurality of channels that perform the same operation. The satellite acquisition information such as code phase, frequency, signal level and the like at the time of code synchronization of a plurality of channels performed by the GPS reception means 102 is sent to the positioning calculation means 105, and the positioning calculation means 105 receives the satellite acquisition information from the GPS reception means 102. Performs positioning calculation based on, and outputs the positioning result.

  The frequency comparison means 106 is for maintaining the clock of the GPS clock source 103 accurately, and compares the reference clock signal with the clock signal output from the GPS clock source 103 to obtain frequency difference information on the clock frequency of the GPS reception means. Is output. The frequency correction control means 107 corrects the clock of the GPS receiving means 102 from the frequency difference information of the clock frequency of the GPS receiving means and outputs a so-called search reference frequency (fs) as a center for performing a satellite search. The search control means 104 sets a search range for searching for satellites according to the search reference frequency (fs) output from the frequency correction control means 107. The search range is set to the number of channels that can be searched simultaneously by the GPS receiving means 102. The frequency range to be searched is changed by the set search range until the code synchronization in each channel of the GPS receiving means 102 is completed. The search control means 104 also determines whether the search is complete.

  In the present invention, in addition to the above configuration, a trigger detection means 108 and a search range correction control means 109 are provided. Although the detailed internal configuration of the trigger detection means 108 is not shown in FIG. The trigger detection means 108 has timer means for measuring time, and is configured to detect whether or not a situation that triggers a change in the search range has occurred with respect to the search situation with respect to the time axis. As a specific operation, the GPS receiver 100 monitors the search status every predetermined time starting from the time when the satellite radio wave search is started. If the satellite radio wave can be received within the predetermined time, the trigger output is not output. When the satellite radio wave is not received within the time or S / N is not obtained even if it is received, a trigger output to change the search range is output. The search range correction control means 109 receives the frequency difference information of the clock from the frequency comparison means 106 and also receives the trigger output from the trigger detection means 108 just described. The search range correction information indicating how much correction should be performed is output. The search control unit 104 sets a search range for the search reference frequency output from the frequency correction control unit 107 based on the search range correction information output from the search range correction control unit 109. Then, until the code synchronization in each channel of the GPS receiving means 102 is completed, the search control means 104 performs a search by changing the search frequency by the newly set search range.

  FIG. 2 is a flowchart showing the operation of the GPS receiver according to Embodiment 1 of the present invention. In FIG. 2, when a satellite radio wave search is started (step S1), the time is measured from the time when the trigger detection means 108 starts the search, and the search status is monitored. If the satellite radio wave is not received within a predetermined time or if the S / N is not obtained even if it is received, a trigger output for changing the search range is output (YES in step S2).

  When there is a trigger output from the trigger detection means 108, the search range correction control means 109 sets a new search range and changes the search frequency within the set search range. In Embodiment 1 of the present invention, as a method for changing the search range, a plurality of search ranges are determined in advance, a wide search range as the first priority search range, and a second priority search range. As a result, a narrow search range is selected. Therefore, at the first time when the search is started, a wide search range which is the first priority search range is selected (step S3), and the search range is expanded to perform a search in a wide search range (step S5). At this time, the GPS receiving means 102 shows the change in the search range in the left half of FIG. 3 (a), with the search reference frequency (fs) as a reference, from the frequency zero to the maximum change range of the satellite radio wave reception frequency. Attempts to receive satellite radio waves with increasing frequency up to the full width. If the satellite radio wave cannot be received or if sufficient S / N cannot be obtained even if it is received, the reception is not completed (NO in step S7), and the process returns to step S2 in the flowchart. In step S2, if a trigger output is not newly output from the trigger detection means 108, it is determined that there is no change in the situation (NO in step S2), and the satellite radio wave search is performed with the same search range (step S6). Further, when the predetermined time elapses without completing the reception, the trigger detection means 108 outputs a trigger output (YES in step S2). Therefore, the search range is given priority over the wide search range that was given priority over the search range. The selected narrow search range is selected again (step S3). Then, the search range is reduced to perform a search in a narrow search range (step S4). As shown in FIG. 3 (b), the search range is narrowed when a trigger output is received from the trigger detection means 108, as shown in the change in the width of the search range. Then, as shown in FIG. 3A, the right half of FIG. 3A shows the change in the search range, and the GPS receiving means 102 limits the range from zero to the narrow range of the satellite radio wave reception frequency with reference to the search reference frequency (fs). Attempt to receive satellite radio waves at an increased frequency. Thus, when the search range is changed to a narrow search range, the frequency of searches repeated within a predetermined time increases. As the frequency of searches increases, the chance of receiving even a weak satellite signal increases, and the possibility of receiving satellite signals quickly and reliably increases.

  The satellite radio wave reception operation is repeated, and when the satellite radio wave is received and sufficient S / N is obtained, the reception is completed (YES in step S7), and the positioning calculation is performed based on the satellite capture information. Is output and positioning is terminated (step S8).

  As shown in Fig. 3 (a), when the search was started after the reception of the satellite radio wave was interrupted, a search was made with a wide search range selected, and a trigger output was output after a lapse of a predetermined time. If a narrow search range is selected and searched again, the search is frequently repeated centering on the search reference frequency, so the frequency of repeated searches within a predetermined time increases and the probability of receiving satellite radio waves. Will increase. As a result, it is possible to quickly receive satellite radio waves.

  In the present invention, if a satellite radio wave cannot be received within a predetermined time even if a second narrow priority search range is searched, a trigger output is issued, and this time a first wide search range is given priority. To search for satellite radio waves.

  As described above, according to the GPS receiver 100 of the first embodiment of the present invention, when the satellite radio wave cannot be received within a predetermined time, a trigger output is issued to quickly change the search range, and a new By switching to search, satellite radio waves can be received quickly.

  FIG. 4 shows a modification of the first embodiment of the present invention. The flow diagram of FIG. 4 is basically similar to the flow diagram of FIG. 2, but when any radio wave is received in the previous search, even if a sufficient S / N ratio cannot be obtained, the satellite radio wave When a frequency (fo) -like thing is found (YES in step S9), the search range is reduced to a range that includes a frequency that seems to be a satellite radio wave when a search output is selected after a predetermined time and a search is received. (Step S10). As a result, the search range can be narrowed down to a range including frequencies that are likely to be satellite radio waves, and the effect of increasing the frequency of repeating the search within a predetermined time can be obtained. If no satellite radio wave is received in the previous search or if a radio wave frequency (fo) is not found even if any radio wave is received (NO in step S9), a trigger output is output after a predetermined time. When the search range is selected again, the search range is expanded and the search is performed (step S11). As a result, the effect that the search range can be expanded can be obtained.

  In the above description, the GPS has been described as an example of the satellite positioning system (SPS). However, other SPS such as Galileo may be used in place of the GPS.

(Embodiment 2)
FIG. 5 shows a block diagram when the GPS receiver according to Embodiment 2 of the present invention is mounted on an automobile for use in a vehicle-mounted navigation device. The GPS receiver 200 according to the second embodiment of the present invention is connected to the in-vehicle LAN control means 201 of the automobile, and obtains the speed information of the automobile from the vehicle speed detection means 202 of the automobile. For the sake of simplicity, the same blocks as those shown in the block diagram of FIG. 1 of the first embodiment are denoted by the same reference numerals and description thereof is omitted, and other blocks on the vehicle side are also omitted. The illustration and description are omitted.

  In the GPS receiver 200 according to the second embodiment of the present invention, as shown in FIG. 5, the vehicle speed information from the vehicle speed detection means 202 is input to the trigger detection means 203 via the in-vehicle LAN control means 201. . The trigger detection means 203 notifies the search range correction control means 109 in steps of changes in the vehicle speed. The search range correction control unit 109 receives the frequency difference information of the clock from the frequency comparison unit 106 and also receives the trigger output from the trigger detection unit 203. The search range correction control unit 109 specifically corrects the search range to the search control unit 104. The search range correction information indicating whether or not to be output is output. The search control unit 104 sets a search range for the search reference frequency output from the frequency correction control unit 107 based on the search range correction information output from the search range correction control unit 109. Then, until the code synchronization in each channel of the GPS receiving means 102 is completed, the search control means 104 performs a search by changing the search frequency by the newly set search range.

  FIG. 6A shows a change in search frequency. FIG. 6B shows, as an example, changes in the speed of an automobile equipped with the GPS receiver according to the second embodiment of the present invention. As the speed change of the car, the speed range is divided into three stages, low speed driving (VL), medium speed driving (VM), and high speed driving (VH), and the search range of the frequency of the satellite radio wave corresponding to each speed range. Are described as selecting a narrow range of frequencies for low speed travel (VL), a medium range of frequencies for medium speed travel (VM), and a wide range of frequencies for high speed travel (VH). To do. Since the vehicle speed information from the vehicle speed detection means 202 is input to the trigger detection means 203 via the in-vehicle LAN control means 201, as shown in the correspondence relationship between FIG. 6 (a) and FIG. 6 (b), Search for a medium range when driving at medium speed, search for a narrow range when driving at low speed, search within the narrowest range when stopped, and search a wide range when driving at high speed Done.

  In FIG. 6, the speed range of the car is divided into three stages of low speed running (VL), medium speed running (VM), and high speed running (VH), and the search range of the corresponding satellite radio wave frequency is changed to three stages. Although an example has been shown, the search range of the frequency of the satellite radio wave may be increased or decreased linearly corresponding to the increase or decrease of the speed of the automobile. FIG. 7A shows a change in search frequency when the search range is linearly increased / decreased, and FIG. 7B shows an example of a change in vehicle speed. The speed of the automobile changes continuously as shown in FIG. 7B, and the search range also changes continuously corresponding to the speed of the automobile linearly as shown in FIG. 7A. Thus, when the search range is made linear, it can be expected that satellite radio waves can be received more quickly.

  As described above, when the GPS receiver according to Embodiment 2 of the present invention is mounted on an automobile, the situation changes when the trigger detection means 203 of the GPS receiver moves or stops at a high speed. The satellite radio wave is quickly received by changing the search range of the satellite radio wave reception frequency.

  In the above description, the GPS has been described as an example of the satellite positioning system (SPS). However, other SPS such as Galileo may be used in place of the GPS.

(Embodiment 3)
FIG. 8 shows a block diagram when the GPS receiver of Embodiment 3 of the present invention is mounted on a mobile phone device. In the GPS receiving device 300 according to the third embodiment of the present invention, the trigger detection means 301 is connected to the communication terminal control means 302 of the mobile phone device. The communication terminal control unit 302 inputs, to the trigger detection unit 301, control information such as radio information received using the antenna 303 and the radio communication unit 304 of the mobile phone device and an operation mode of the mobile phone device. The wireless communication unit 304 is also configured to input a reference frequency to the frequency comparison unit 106. For the sake of simplicity, the same blocks as those shown in the block diagram of FIG. 1 of the first embodiment are denoted by the same reference numerals and the description thereof is omitted. Illustrations and descriptions of blocks are omitted.

  Here, an example in which handover information is used as radio information received using the antenna 303 and the radio communication unit 304 of the mobile phone device will be described below. A mobile phone device normally performs intermittent transmission / reception with a base station of a mobile phone communication network by radio communication means, monitors the strength of radio wave reception sensitivity, and performs a handover to connect to the base station with the strongest radio wave strength. Yes. In the cellular phone device with a GPS function according to the third embodiment of the present invention, information indicating the handover status is transmitted to the trigger detection unit 301 as the wireless information received using the antenna 303 and the wireless communication unit 304 of the cellular phone device. . The trigger detection unit 301 determines that the user of the mobile phone device has started high-speed movement together with the mobile phone device when the handover is successively repeated to different base stations within a predetermined time, and the frequency at which the handover is performed. When there are few or when handovers between adjacent base stations are repeated, the user of the mobile phone device is not moving with the mobile phone device or is moving at a low speed even if it is moved It is decided to judge. When there is a change in the handover situation, the trigger output is transmitted to the search range correction control means 109. Thus, as already described in the second embodiment, the search of the satellite radio wave can be performed by expanding or reducing the search range in accordance with the change in the moving speed, so that the satellite radio wave can be searched more quickly. Can be received.

  In addition, the mobile phone device includes an operation mode during high-speed movement called a drive mode set when driving a car, a car navigation mode used as a car navigation, a pedestrian navigation mode for guiding a pedestrian's destination, etc. There are operating modes. Therefore, in the present invention, when the operation mode indicating these movement states is set, the trigger detection unit determines that the situation has changed, transmits the trigger output to the search range correction control unit, and changes the search range. It is configured to perform a search.

  FIG. 9 is a flowchart for explaining the operation of the mobile phone device with a GPS reception function according to the third embodiment of the present invention. In FIG. 9, when a search for satellite radio waves is started (step S701), the trigger detection means 301 determines whether there is a change in the situation. If it is determined that the situation has changed (YES in step S702), whether the situation change is that the number of handovers is greater than a predetermined value (step S703), the drive mode is set (step S704), car navigation Whether the mode is set (step S705) or the navigation mode for pedestrians is set (step S706). When the number of handovers is greater than a predetermined value (YES in step S703), when the drive mode is set (YES in step S704), or when the car navigation mode is set (YES in step S705), the mobile phone device It is determined that the user has started high-speed movement with the mobile phone device, and a search is made with a wide search range (step S707). When the pedestrian navigation mode is set (YES in step S706), the search is performed in the intermediate search range (step S708). Other situation changes not corresponding to any of steps S702 to S706 are searched in a narrow search range (step S709). If the satellite radio wave is searched in any of the search ranges and the satellite radio wave cannot be received or if a sufficient S / N ratio cannot be obtained even if it is received, the process returns to step S702. The search is continued within the search range (step S711). If there is a new situation change in the middle, the search is switched to the corresponding search range. The process is repeated until the reception of the satellite radio wave is completed. If the satellite radio wave is received and sufficient S / N is obtained, the reception is completed (YES in step S710), the positioning calculation is performed based on the satellite capture information, the positioning result is output, and the positioning is finished (step). S712).

  As described above, a user having a GPS receiving function-equipped mobile phone device equipped with the GPS receiving device according to the third embodiment of the present invention starts moving at a high speed on a car or a bullet train, or starts walking. When the operation is stopped, the trigger detection unit 301 determines that the situation has changed, outputs a trigger, and changes the search range to a range in which satellite radio waves can be easily received. The effect that it can be obtained.

  In the above description, the GPS has been described as an example of the satellite positioning system (SPS). However, other SPS such as Galileo may be used in place of the GPS.

  The SPS receiver and the mobile communication terminal device with an SPS reception function of the present invention can be widely applied not only to in-vehicle navigation equipped with a GPS receiver and mobile phones with a GPS reception function, but also to electronic devices that use SPS information. .

Block diagram of the GPS receiver according to the first embodiment of the present invention. The flowchart which shows operation | movement of the GPS receiver concerning Embodiment 1 of this invention. (A) The figure which shows the change of the search frequency of the GPS receiver concerning Embodiment 1 of this invention (b) The figure which shows the change of the search range of the GPS receiver concerning Embodiment 1 of this invention The flowchart which shows other operation | movement of the GPS receiver concerning Embodiment 1 of this invention. Block diagram of a mobile communication terminal device with a GPS reception function according to a second embodiment of the present invention (A) The figure which shows the change of the search frequency of the GPS receiver concerning Embodiment 2 of this invention (b) The figure which shows the change of the moving speed of the GPS receiver concerning Embodiment 2 of this invention (A) The figure which shows the change of the search frequency of the other GPS receiver concerning Embodiment 2 of this invention (b) The figure which shows the change of the moving speed of the other GPS receiver concerning Embodiment 2 of this invention Block diagram of a mobile communication terminal device with a GPS reception function according to a third embodiment of the present invention The flowchart which shows operation | movement of the mobile communication terminal device with a GPS receiving function concerning Embodiment 3 of this invention. (A) The figure which shows the change of the search frequency by the satellite radio wave supplement method in the conventional GPS receiver. (B) The figure which shows the change of the moving speed of the conventional GPS receiver.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 GPS receiver 101 GPS antenna 102 GPS receiving means 104 Search control means 105 Positioning calculation means 107 Frequency correction control means 108 Trigger detection means 109 Search range correction control means

Claims (7)

In an SPS receiver that receives radio waves from a satellite,
Trigger detection means for detecting, as a trigger, a status change in which the SPS receiver is placed;
Search range correction control means for changing the range of the SPS reception frequency to be searched is provided,
When a predetermined situation change is detected as a situation where the SPS receiver is placed by the trigger detection means,
An SPS receiver configured to receive radio waves from a satellite by expanding or reducing a range of SPS reception frequencies to be searched by the search range correction control means. The SPS receiver according to claim 1,
The trigger detection means detects, as a trigger, a status change every predetermined time in a reception state whether or not a radio wave from a satellite has been received within a predetermined time,
An SPS receiver configured to receive radio waves from a satellite by expanding or reducing a range of SPS reception frequencies to be searched by the search range correction control means. The SPS receiver according to claim 2,
The search range correction control means, when the trigger detection means could not receive the radio wave from the satellite within a predetermined time,
An SPS receiver configured to receive a radio wave from a satellite by reducing the range of the SPS reception frequency to be searched by the search range correction control means. The SPS receiver according to claim 1,
The trigger detection means detects, as a trigger, a change in the state of movement such as whether the SPS receiver is stationary or moving at a predetermined speed,
An SPS receiver configured to receive radio waves from a satellite by expanding or reducing a range of SPS reception frequencies to be searched by the search range correction control means. A mobile communication terminal receiving apparatus with an SPS function, wherein the SPS receiving apparatus according to any one of claims 1 to 4 is mounted. The mobile communication terminal device with an SPS receiving function according to claim 5,
The trigger detection means detects, as a trigger, a status change of a handover with a base station every predetermined time of the mobile communication terminal device with the SPS reception function,
A mobile communication terminal apparatus with an SPS receiving function, wherein the search range correction control means is configured to receive a radio wave from a satellite by expanding or reducing a range of an SPS reception frequency to be searched. The mobile communication terminal device with an SPS receiving function according to claim 5,
The trigger detection means detects a change in the operating mode of the mobile communication terminal device with the SPS reception function as a trigger,
A mobile communication terminal apparatus with an SPS receiving function, wherein the search range correction control means is configured to receive a radio wave from a satellite by expanding or reducing a range of an SPS reception frequency to be searched.

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