JP4640485B2 - Navigation device and control method thereof - Google Patents

Description

The present invention relates to a navigation device for automobiles and the like, and a control method for the navigation device.

  Conventionally, automobile navigation devices using GPS (Global Positioning System) have been widely used. In this type of navigation apparatus, latitude information and longitude information of the current position are calculated based on signals from a plurality of artificial satellites received by a GPS antenna, and roads around the current position read from a recording medium such as a CD-ROM. Map data consisting of information and place name information is developed and displayed on a monitor display.

  However, in the GPS, since signals received from each satellite include various error factors such as an ionospheric delay error and a tropospheric delay error that change the signal arrival time, satellites including these error factors are included. An error inevitably occurs in the movement position measured based on the signal.

  Therefore, in a fixed reference station whose precise position on the earth is known in advance, the reference station position is measured by the GPS, and a correction signal corresponding to the difference between the measured position and the previously known reference station position is created. By transmitting as a data multiplex broadcast, the mobile unit receives a plurality of satellite signals and measures the movement position thereof, and the measured movement position is multiplexed and received as the FM broadcast. A differential GPS, so-called D-GPS, is obtained in which the moving position of the moving body is obtained with extremely high accuracy by performing correction according to the above.

  Therefore, in the navigation device corresponding to this D-GPS, the movement position can be detected with extremely high accuracy by attaching or incorporating the FM multiplex tuner.

  Recently, a VICS (Vehicle Information and Communication System) service that provides traffic information and the like has started in some areas. This service provides traffic information such as traffic jams, accidents, regulations, etc. in the form of text, simple graphics, or maps by FM data multiplex broadcasting, optical beacons or radio beacons.

  However, if the navigation device corresponding to the D-GPS system receives the VICS service by FM data multiplex broadcasting, the D-GPS correction information, the VICS traffic information, and the like can be obtained by one FM multiplex tuner. Must receive.

  Therefore, there is no problem when the D-GPS correction information and the VICS traffic information are multiplexed on the same frequency FM broadcast radio wave, but the D-GPS correction information and the VICS traffic information have different frequencies. When multiplexed on FM broadcast radio waves, these two types of information must be obtained by manually switching the frequency, or two FM multiplex tuners must be provided. The former method of manually switching the frequency is very complicated and impractical, and the latter having the two FM multiplex tuners leads to an increase in the size and cost of the apparatus.

The present invention has been made in view of the above circumstances, and the object of the present invention is to receive D-GPS and VICS data almost simultaneously even when reception frequencies differ by one FM multiplex tuner. It is an object of the present invention to provide a possible navigation device and a method for controlling the navigation device.

Invention of claim 1, wherein the map data storage means for map data is stored including road information, a positioning means for positioning a current position based on signals transmitted from multiple satellites, multiple radio wave transmission release receiving means for receiving the data transmitted is of a first reception control means for receiving the data of transportation information to the receiving means, the signals transmitted from the multiple satellites to the reception means A second reception control means for receiving the error information data, and any one of the traffic information data and the error information data multiplexed and transmitted on the broadcast radio wave by the first or second reception control means. After receiving one, the third reception control means for receiving the other data by changing the frequency by the first or second reception control means, the current position obtained by the positioning means, and the second Reception control means Map data from the map data storage means on the basis of the data of the error information obtained by reading a map data development means for developing the display data by using the data of the traffic information obtained in the first reception control means and changing means for changing the display data obtained by the map data expansion means, comprising a display means for displaying the display data obtained by this changing means, the third reception control means, the data of the traffic information A navigation characterized in that the switching timing of the first and second reception control means is set based on a content update period or a value of specific data in the correction data set of the satellite related to the error information data. A device .

  With such a configuration, error information data and traffic information data are received almost simultaneously even if the reception frequency differs by one multiplex radio tuner, and traffic information is displayed on the surrounding map including the accurate current position. Can be displayed.

According to a second aspect of the present invention, the second reception control means receives data by performing a frequency search, and the frequency search is started from the reception frequency of the first reception control means. The navigation device according to claim 1 .

With such a configuration, in addition to the operation of the first aspect of the invention, the frequency search time can be shortened .

According to a third aspect of the present invention, the first and second reception control means receive data by performing a frequency search. The frequency search of the first and second reception control means is performed once. 2. The navigation apparatus according to claim 1, wherein after the specified frequency information is secured, tuning is controlled based on the frequency information without performing a frequency search again .

With such a configuration, in addition to the operation of the first aspect of the invention, the frequency search is omitted after the frequency search is performed once, so that the time required for the frequency search can be omitted.

According to a fourth aspect of the present invention, the data reception period of the first reception control means is configured to vary depending on the value of specific data in the correction data set of the satellite. Navigation device .

With such a configuration, in addition to the operation of the first aspect of the invention, a data reception period can be set according to the situation.

According to a fifth aspect of the present invention, in the navigation device according to the first aspect, the data reception period of the second reception control means is a period in which only predetermined information is received .

With such a configuration, in addition to the operation of the first aspect of the present invention, it is only necessary to receive the minimum necessary data, and the reception time can be shortened.

The invention according to claim 6 is a map data storage means in which map data including road information is stored, a positioning means for positioning the current position based on signals transmitted from a plurality of satellites, and multiplexed on broadcast radio waves. And a receiving means for receiving the transmitted data, the first receiving control step for causing the receiving means to receive the traffic information data, and the receiving means for receiving the plurality of data. A second reception control step for receiving error information data relating to a signal transmitted from the satellite, and traffic information data multiplexed and transmitted by the first or second reception control step. And a third reception control step for receiving the other data by changing the frequency in the first or second reception control step after receiving one of the error information data and the measurement data. A map data developing step of reading out map data from the map data storage means based on the current position obtained by the means and the error information data obtained in the second reception control step, and developing the map data as display data; A change step for changing the display data obtained in the map data expansion step using the traffic information data obtained in the reception control step, and a display step for displaying the display data obtained in the change step. In the reception control step, the first and second reception control steps are based on the update period of the content of the traffic information data or the value of specific data in the correction data set of the satellite related to the error information data. The navigation device control method is characterized in that the switching timing is set .

  With such stored contents, error information data and traffic information data are received almost simultaneously even if the reception frequency differs by one multiplex radio tuner, and traffic is displayed on the surrounding map including the accurate current position. It can be displayed as a reflection of information.

  According to the first aspect of the present invention, the error information data and the traffic information data are received almost simultaneously even when the reception frequency is different by one multiplex radio tuner, and is displayed on the surrounding map including the accurate current position. It can be displayed as reflecting traffic information.

According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the frequency search time can be shortened .

According to the invention described in claim 3, in addition to the effect of the invention described in claim 1, the frequency search is omitted after the frequency search is performed once, so that the time required for the frequency search can be omitted.

According to the invention described in claim 4, in addition to the effect of the invention described in claim 1 , a data reception period can be set according to the situation.

According to the invention described in claim 5, in addition to the effect of the invention described in claim 1 , it is only necessary to receive the minimum necessary data, and the reception time can be shortened.

According to the sixth aspect of the present invention, error information data and traffic information data are received almost simultaneously even when reception frequencies differ by one multiplex radio tuner, and are displayed on a surrounding map including an accurate current position. It can be displayed as reflecting traffic information.

(First embodiment)
A first embodiment in the case where the present invention is applied to an automobile navigation apparatus using GPS and FM data multiplex broadcasting will be described below with reference to the drawings.

  FIG. 1 shows a circuit configuration of the entire apparatus. As a GPS reception function, a GPS antenna 1 installed on a roof of a vehicle body and an L1 band (1.57542 GHz) from a plurality of GPS satellites received by the GPS antenna 1 are shown. ) C / A code data is demodulated and decoded by a despreading LSI, and the GPS block 2 for calculating the latitude, longitude, height, time, etc. of the current location is included.

  The GPS block 2 is connected to a graphic block 3. The graphic block 3 includes an FM antenna 4, a key block 5 having various input keys such as a mode key and a cursor key, which will be described later, road information, and place name information. A CD block 6 having a CD-ROM, which is a recording medium on which the map data and the operation program are recorded, is mounted, for example, a monitor block 7 having a display device composed of a color LCD panel and its drive circuit. Yes.

  The graphic block 3 is provided with a CPU 13 for controlling the entire apparatus based on an operation program read from the CD-ROM of the CD block 6 and stored in the flash EEPROM 11 and various data stored in the RAM 12.

  Further, in the graphic block 3, an FM tuner 14 for demodulating FM radio waves received by the FM antenna 4 to obtain an FM demodulated signal of a desired broadcasting station, connected to the FM tuner 14 and multiplexed on the FM demodulated signal. An FM multiplex decoder 15 that decodes data, a CPU peripheral circuit gate array (G / A) 16 that mainly controls input / output of data between the GPS block 2, the key block 5 and the CD block 6 and the CPU 13, The graphic controller 17 is connected to the flash EEPROM 11, RAM 12, and CPU 13 via a bus, and a video RAM 18 is connected to the graphic controller 17.

  When traveling on the road, the CPU 13 sends the latitude and longitude data of the current location, that is, the position data together with data representing other heights, times, and the like from the GPS block 2, and the FM decoded by the FM multiplex decoder 15. This is corrected by error information data based on D-GPS of data multiplex broadcasting, and map data around the current location is called from the CD block 6 via the CPU peripheral circuit G / A 16 with the corrected position data, and the video RAM 18 is displayed as display data. Is transmitted to the graphic controller 17 connected to the same, while the traffic information based on the VICS of the FM data multiplex broadcast similarly decoded by the FM multiplex decoder 15 is read if necessary, and is expanded and transmitted to the graphic controller 17. And superimposed on the display data of the video RAM 18.

  The graphic controller 17 develops map data on which the traffic information sent from the CPU 13 is superimposed on the video RAM 18 to create display data for each screen, and sends the created display data to the monitor block 7 for traffic. Display information and map.

  FIG. 2 shows an external configuration of the remote control unit 20 mainly constituting the key block 5, FIG. 2 (a) is a left side view, and FIG. 2 (b) is a top view.

  The remote control unit 20 is a wired remote controller in which a remote control body case 21 is connected by a cable. As shown in FIG. 2A, a power switch for turning on / off the power by a slide switch on the left side surface of the remote control body case 21 22 is provided.

  Further, as shown in FIG. 2B, on the upper surface of the remote control main body case 21, a power LED 23, a NAVI / CD key 24, a TV key 25, an FM DATA key 26, a MENU key 27, a cursor key 28, an ENTER key 29, A position key (shown as “POS” in the figure) 30, a scale change / tuning key 31, a MARK key 32, a POINT key 33, a HOME key 34 and a VIDEO key 35 are provided.

  The power LED 23 is lit in red when the power switch 22 is turned on.

  The NAVI / CD key 24 is a key operated when a navigation operation is performed by the present apparatus or when a music CD is mounted on the CD block 6 for listening to music although not described in the present embodiment.

  The TV key 25 is a key that is operated when a television tuner (not shown) is connected to the graphic block 3 and the television block is viewed on the monitor block 7, although the description is omitted in the present embodiment. The FM DATA key 26 is These keys are operated when displaying the FM data multiplex broadcast character information obtained from the FM multiplex decoder 15 on the monitor block 7.

  The MENU key 27 is a key for instructing display of a menu screen. The cursor key 28 is a ring-shaped key for instructing movement of the cursor displayed on the display screen of the monitor block 7 in the up, down, left and right directions on the menu screen. The key 29 is a key for operating and instructing an icon or the like indicated by the cursor on the display screen by the movement of the cursor key 28.

  The position key 30 is a key for displaying the latitude, longitude, etc. of the current location determined by the antenna 1 and the GPS block 2, and the scale change / tuning key 31 is an instruction to change the scale of the map displayed during the navigation operation. On the other hand, it is a key for instructing up / down tuning during a television or radio reception operation.

  Further, the MARK key 32 is a key for marking a passing position or the like in the route guidance function at an arbitrary position of the map data, and the POINT key 33 is a destination setting or screen scrolling to the destination side when the route guidance function is operated. Similarly, the HOME key 34 is a key for setting the current location and scrolling the screen to the current location when the route guidance function is operated.

  The VIDEO key 35 is a key that is operated when a video camera or the like (not shown) is connected to the graphic block 3 and the video is viewed on the monitor block 7 although not described in the present embodiment.

  Next, the operation of the first embodiment will be described.

  3 to 7 show the setting states of D-GPS and VICS, respectively. That is, when the MENU key 27 of the remote control unit 20 is pressed during execution of a navigation operation for displaying a map including the current position, a menu screen is displayed on the monitor block 7 as shown in FIG. Here, when the ENTER key 29 is operated with the item “D-GPS / VICS setting” specified by the operation of the cursor key 28 as shown in FIG. 3, a submenu screen is displayed as shown in FIG.

  In the submenu screen of FIG. 4, “D-GPS / VICS ON” for turning on both functions of D-GPS and “D-GPS ON” for turning on only the function of D-GPS. ”And“ VICS ON ”for turning on only the VICS function, and the top“ D-GPS / VICS ON ”is highlighted.

  When the ENTER key 29 is operated from the state in which “D-GPS / VICS ON” shown in FIG. 4 is highlighted, the map including the current position symbol P in the monitor block 7 is displayed as shown in FIG. The first symbol S1 indicates that the D-GPS function is set to ON at the left end of the screen, and that error information data is multiplexed on a broadcast wave having a frequency of, for example, “80.0 [MHz]”. In addition, when the VICS function is set to ON, the traffic information data is multiplexed with a broadcast wave having a frequency of, for example, “82.5 [MHz]”, and the latest information is the time “14:25”. Is displayed together with a direction symbol D representing the direction of the map in the second symbol S2, while the road section is crowded based on traffic information obtained by the VICS function in the map Display by adding a color different arrows as relatively open to the road section example shown has.

  When the cursor key 28 is operated from the display state of the submenu screen shown in FIG. 4 and the ENTER key 29 is operated while “D-GPS ON” is highlighted, the monitor block is displayed as shown in FIG. The D-GPS function is set to ON at the left end of the map screen including the current position symbol P in FIG. 7, and the error information data is multiplexed into a broadcast radio wave having a frequency of “80.0 [MHz]”, for example. This is displayed together with an orientation symbol D representing the orientation of the map by the first symbol S1.

  Furthermore, when the cursor key 28 is operated from the display state of the submenu screen shown in FIG. 4 and the ENTER key 29 is operated in a state where “VICS ON” is highlighted, the monitor block 7 as shown in FIG. The VICS function is set to ON at the left end of the map screen including the current position symbol P, and the traffic information data is multiplexed with the broadcast radio wave with a frequency of “82.5 [MHz]”, for example. Is displayed at the time “14:25” together with the direction symbol D representing the direction of the map by the second symbol S2, while the map is based on the traffic information obtained by the VICS function. The crowded road section and the relatively empty road section are displayed by adding arrows of different colors as shown in the figure, for example.

  FIG. 8 shows the current position from the FM multiplex decoder 15 when the CPU 13 acquires the position data from the GPS block 2 and at the same time the D-GPS function and the VICS function are both turned on as shown in FIG. A processing procedure for acquiring error information data and traffic information data is shown. Initially, a search for traffic information data by VICS is started (step A01), and the first is set in the RAM 12 as well. The timing by the timer is started (step A02).

  Here, the search of the traffic information data by VICS is performed for the frequency band of FM radio broadcasting by the FM tuner 14, for example, 0.1 [MHz] from 76.0 [MHz] to 90.0 [MHz] by the auto tuning function. If the search is stopped due to the broadcast radio wave, it is judged whether or not the data multiplex broadcast is being performed. If the data multiplex broadcast is being performed, it is received for one frame. Thus, it is determined whether or not those programs are based on VICS (step A03), and the first timer of the RAM 12 counts the traffic information update period in the VICS service, for example, “5 minutes”. Is to do.

  Here, although the update period of traffic information in the VICS service is “5 minutes”, it is assumed that this is provided by repeating traffic information in units of “2 minutes 30 seconds” twice.

  In step A03, there is no broadcast radio wave at the frequency, or even if there is no data multiplex broadcast, or even if there is a data multiplex broadcast, there is no program based on VICS. If it is determined, it is then determined whether or not the search has been completed one round, that is, whether or not there is nothing by the VICS even at the last frequency 90.0 [MHz] in the same frequency band (step A04).

  However, if it is determined in step A04 that the search has not made one round, the received frequency is further increased by 0.1 [MHz] and the operation from step A03 is repeated.

  When it is determined in step A03 that there is a broadcast radio wave and data multiplex broadcasting is being performed, and that there is a program based on VICS, the unit of traffic information “2 minutes 30” set in the RAM 12 is determined. After starting the time measurement of the second timer that measures "second" (step A05), the VICS traffic information received at the frequency is temporarily stored in the RAM 12 (step A06).

  Thereafter, it is determined whether or not the time value of the second timer in the RAM 12 has reached the above-mentioned limit value “2 minutes 30 seconds” (step A07). If it is determined that it has not, the process returns to step A06 again. The VICS traffic information data received in this manner is repeatedly stored in the RAM 12.

  When it is determined in step A07 that the time value of the second timer of the RAM 12 has reached the limit value “2 minutes 30 seconds”, the traffic information data of VICS has been completely received. Therefore, it is then determined whether or not the error information data by D-GPS can be received at the same frequency at which this VICS traffic information data is received without changing the reception frequency by FM tuner 14 (step A08). ).

  The error information data by D-GPS is inserted in a predetermined packet position in one frame of data multiplex broadcast data, for example, the first and second packets, and it is necessary to receive all one frame. Instead, the determination can be made based on whether or not the packet is at the predetermined packet position.

  However, there is no D-GPS error information data at the packet position in step A08, and it is not possible to receive D-GPS error information data at the same frequency as the VICS traffic information data is received. If it is determined, the search for error information data by D-GPS is started next time (step A09).

  Here, the error information data search by the D-GPS is performed again using the auto-tuning function in the frequency band of the FM radio broadcast by the FM tuner 14, for example, from 76.0 [MHz] to 90.0 [MHz]. [MHz] Steps are received in sequence, and if the search is stopped due to broadcast radio waves, it is determined whether or not data multiplex broadcasting is being performed, and if data multiplex broadcasting is being performed, the specified in the frame It is determined whether or not there is a packet position by D-GPS (step A10), and there is no broadcast radio wave at the frequency, or even if there is no data multiplex broadcast, or the data multiplex broadcast is If it is determined that there is no D-GPS program among those programs, then whether or not the search has been completed once, Ie even in the last frequency 90.0 [MHz] of the same frequency band is determined whether there is no by the D-GPS (step A11).

  However, when it is determined in step A11 that the search has not made one round, the received frequency is further increased by 0.1 [MHz], and the operation from step A10 is repeatedly executed.

  Then, when it is determined in step A10 that there is a broadcast radio wave and data multiplex broadcasting is being performed, and that there is a D-GPS program in those programs, the error information of the D-GPS received at that frequency Are temporarily collected in the RAM 12 (step A12).

  Thereafter, it is determined whether or not the measured value of the first timer of the RAM 12 has reached the above-mentioned limit value “5 minutes” (step A13). The process of collecting the D-GPS error information data in the RAM 12 is repeatedly executed.

  Then, when it is determined in step A13 that the time value of the first timer of the RAM 12 has reached the above-mentioned limit value “5 minutes”, the above-described step A01 is again performed in order to receive the updated traffic information data by VICS. Return to.

  If it is determined in step A04 that the search has made one round without receiving the traffic information data by VICS, it is determined that the data could not be received, and the process proceeds to step A09. Shifts to a search for receiving error information data by D-GPS.

  Further, when it is determined that the error information data by D-GPS can be received at the same frequency as the frequency at which the traffic information data by VICS is received in step A08, the search operation by steps A09 to A11 is performed. Therefore, the process proceeds to step A12 as it is, and the error signal data by D-GPS received at the reception frequency is collected in the RAM 12.

  Further, if it is determined in step A11 that the search has been completed once without receiving error information data by D-GPS, it is determined that the data could not be received, and the process directly returns to step A01. Then, a search for reception of traffic information data by VICS is performed again.

  The map data read from the CD block 6 is developed after correcting the current position data obtained from the GPS block 2 based on the error information data by D-GPS stored in the RAM 12 as described above, and further developed. By displaying the VICS traffic information data stored in the RAM 12 in a superimposed manner on the map data, the screen as shown in FIG. 5 can be obtained.

  In addition, there are actually three types of traffic information data by the above VICS, “Level 1” to “Level 3”. As described above, the “Level 3” data is used as the data to be directly superimposed on the map data. As an example, a window may be provided in a part of the map data so that characters according to “level 1” or simple figures according to “level 2” may be superimposed and displayed.

  Further, when only the D-GPS function is set to be turned on as shown in FIG. 6, the processes of steps A01 to A08 are omitted and the processes of steps A09 to A13 (except for the timer process) are performed. Run only.

  On the other hand, when only the VICS function is set to be turned on as shown in FIG. 7, the processes in steps A08 to A13 are omitted and only the processes in steps A01 to A07 (except for the timer process) are performed. Execute.

  Further, in the above embodiment, when the function of the D-GPS is turned on / off, the display screen of the monitor block 7 has only been determined based on the presence or absence of the second symbol S2, but as shown in FIG. The size of the current position symbol P displayed in the map data may be variably set depending on when the function is turned on / off.

  FIG. 10 exemplifies the display screen of the monitor block 7 when the D-GPS function is set to OFF or when error information by D-GPS is not obtained as a result of search while being set to ON. Since the first symbol S1 'is displayed at the left end of the screen that the D-GPS function is off, and the error of the current position is about 100 [m] at the maximum, it is also shown in FIG. Thus, the current position symbol P having a large diameter is displayed in the map data.

  On the other hand, FIG. 11 illustrates a display screen of the monitor block 7 when the D-GPS function is set to ON and the D-GPS data is actually received from the FM multiplex decoder 15. The D-GPS function is set to ON at the left end of the screen, and the error information data is received after being multiplexed with a broadcast wave having a frequency of “80.0 [MHz]”, for example. 1 and the current position error P is corrected to about 1/10 of that when the D-GPS function is turned off. Therefore, as shown in FIG. It is displayed inside.

  Note that the first symbol S1 ′ when the D-GPS function is off in FIG. 10 and the first symbol S1 when the D-GPS function is on in FIG. 11 are, for example, the first symbol S1 when the D-GPS function is off. By displaying ′ in gray and the first symbol S1 when the D-GPS function is turned on in different colors such as green, it becomes more clearly visible.

  In the flowchart of FIG. 8, the D-GPS search monitoring may be started from the VICS reception frequency. Furthermore, after searching each reception frequency of VICS and D-GPS and receiving it, tuning may be controlled based on the frequency information without performing a search.

(Second Embodiment)
A second embodiment in the case where the present invention is applied to an automobile navigation device using GPS and FM data multiplex broadcasting will be described below with reference to the drawings.

  Note that the circuit configuration of the entire apparatus is basically the same as that shown in FIG. 1 and the external configuration of the remote control unit is basically the same as that shown in FIG. Is omitted.

  FIG. 12 shows a circuit configuration centering on the FM tuner 14. The FM tuner 14 includes an FM receiver 14a, a demodulator 14b, a channel selection controller 14c, and a time correction unit 14d as shown.

  The FM receiving unit 14a selects a frequency corresponding to the tuning voltage VT input from the channel selection controller 14c from the radio wave received by the FM antenna 4, converts the frequency into an intermediate frequency signal, and outputs the intermediate frequency signal to the demodulation unit 14b. The demodulator 14b performs processing such as FM demodulation on the intermediate frequency signal to obtain an FM demodulated signal, and sends the obtained FM demodulated signal to the FM multiplex decoder 15.

  The FM multiplex decoder 15 outputs VICS, D-GPS data, etc. obtained by decoding the data multiplexed in the FM audio signal to the CPU 13, while at the head position of each block in the D-GPS data. A BIC (Block Identification Code) signal added to establish block synchronization and frame synchronization is detected and sent to the time correction unit 14 d of the FM tuner 14.

  The time correction unit 14d reads the BIC signal from the FM multiplex decoder 15 and corrects the switching timing of the channel selection operation by the channel selection controller 14c according to the timing. The channel selection controller 14c generates a tuning voltage VT based on an internal clock count during the channel selection operation based on an instruction from the CPU 13, and outputs the tuning voltage VT to the FM reception unit 14a. The switching timing thereof is the time correction unit 14d. It is corrected by the signal from

  As shown in FIG. 13 (1), VICS data is multiplexed and transmitted on FM broadcast radio waves having a frequency of 82.5 [MHz]. On the other hand, as shown in FIG. It is assumed that D-GPS data is multiplexed and transmitted on FM broadcast radio waves of [MHz].

  The position of the 80.0 [MHz] D-GPS data G is fixed in advance in the first two packets (blocks) of each frame as shown in the figure. In addition, since frame synchronization between the frequencies is not achieved, the reception timing is different between the multiplexed data frame of frequency 80.0 [MHz] and the multiplexed data frame of 82.5 [MHz]. .

  The data multiplexed in the FM broadcast has 272 blocks of packets transmitted at 5 (seconds) per frame, and the top two data packets are allocated as D-GPS transmission packets as described above.

  FIG. 14 is a diagram showing the contents of the D-GPS data assigned to the two packets. That is, as the D-GPS data, following the data identification number (data ID) and the correction value data creation time (Time of Correction), for example, reception from the first to eighth GPS satellites is performed. A correction data set corresponding to each satellite obtained based on the signal, and communication data (communication data) indicating normality / abnormality of each satellite are provided.

  FIG. 15 is a diagram showing the contents of the correction data set of each satellite given as the D-GPS data. That is, for example, correction data sets corresponding to each of the satellites 1 to 8 include a pseudo distance correction value (PRC) scale factor (Scale Factor: SF), a user differential distance error index (User Differential Range Error: UDER). , Satellite identification number (Satellite ID: St. ID), pseudo-range correction value (Pseudorange Correction: PRC), distance change rate correction value (Range) which is the rate of change of the pseudo-range correction value (PRC) per second. Rate Correction (RRC) and a data issue number (Issue Data: IODE) indicating satellite orbit data are given.

  Next, specific processing contents during operation will be described with reference to FIG.

  As pre-processing for starting this processing, D-GPS data is received and stored, and frame synchronization and block synchronization are established for multiplexed data of frequency 80.0 [MHz] that is transmitting D-GPS data. It shall be.

  At the beginning of the process, the CPU 13 sends a control signal instructing the selection of the frequency of the FM broadcast in which the VICS data is multiplexed to the tuning controller 14c of the FM tuner 14 in order to receive the VICS data. The channel selection controller 14c generates a tuning voltage VT corresponding to the frequency, for example, 82.5 [MHz] shown in FIG. 13 (1), and sends the tuning voltage VT to the FM receiver 14a to select the broadcast of the frequency. (Step B01).

  When the FM receiver 14a selects and receives a broadcast wave of 82.5 [MHz] according to the tuning voltage VT and outputs an FM demodulated signal from the demodulator 14b, the FM multiplex decoder 15 is multiplexed with the FM demodulated signal. The BIC is output to the time correction unit 14d, while the VICS data is output to the CPU 13 (step B02).

  Here, the CPU 13 reads the RRC shown in FIG. 15 in the D-GPS data already received and held in the RAM 12, and the value is set to a preset value, for example, 0.1 [m / Second] is exceeded (step B03), and does not exceed 0.1 [m / second], and the current position data obtained from signals from each GPS satellite is relatively accurate. If it is determined that there is, then it is determined whether or not 12 frame periods (1 minute) have elapsed since the reception of this VICS data (step B04). If not, the process returns to step B02 again. Return to continue receiving VICS data.

  If it is determined in step B03 that the RRC value stored in the RAM 12 exceeds a preset value, for example, 0.1 [m / sec], the signal from each GPS satellite is used. Assuming that the obtained current position data contains a relatively large amount of error, it is then determined whether or not six frame periods (30 seconds) have elapsed since the reception of this VICS data (step B05). If not, the process returns to step B02 again to continue receiving VICS data.

  In this way, when VICS data is continuously received for a plurality of frame periods corresponding to the RRC value and it is determined that the period has ended (frame start timing of multiplexed data at 80.0 [MHz]) ( Step B04, B05), and then the CPU 13 sends a control signal to the channel selection controller 14c of the FM tuner 14 to instruct the selection of the frequency of the FM broadcast in which the D-GPS data is multiplexed. The controller 14c generates a tuning voltage VT corresponding to the frequency, for example, 80.0 [MHz] shown in FIG. 13 (2), and sends the tuning voltage VT to the FM receiver 14a to select the broadcast of the frequency (step). B06).

  After channel selection, the channel selection controller 14c starts the operation of an internal timer (indicated as "timer 3" in the figure) for measuring the D-GPS data reception time (2 blocks) at the start timing of the frame. After that, when the FM receiver 14a receives a broadcast wave of 80.0 [MHz] according to the tuning voltage VT and outputs an FM demodulated signal from the demodulator 14b, the FM multiplex decoder 15 performs the FM demodulation. The data multiplexed in the signal is decoded and the BIC is output to the time correction unit 14d, while the obtained D-GPS data is output to the CPU 13 (step B08).

  At this time, the time correction unit 14d detects the timing when the start position of the 80.0 [MHz] multiplexed data block is detected by the change in the bit pattern of the BIC sequentially sent from the FM multiplex decoder 15, and performs the above selection. This is to correct the internal timer (the timer 3 and the frame timer) of the station controller 14c, and then it is determined whether or not the two packet periods have elapsed by the time count of the timer 3 of the channel selection controller 14c (step B09). If it has not elapsed, the process returns to step B08 again to continue receiving D-GPS data.

  Then, when it is determined that two packet periods have elapsed as a result of the timer 3 of the channel selection controller 14c, differential correction value generation and other processes described later are executed based on the received D-GPS data, and the above steps are performed again. Returning to B01, the process returns to the VICS data reception process.

  However, every time two packets of the D-GPS data are received, the CPU 13 simultaneously executes a differential correction value generation process shown below.

  FIG. 17 shows the processing contents. The CPU 13 waits for the update of the D-GPS data received by the FM multiplex decoder 15 at any time (step C01), and from the GPS block 2 when it is determined that the update has been made. The current satellite reception time is read (step C02).

  The CPU 13 determines the difference between the satellite reception time read from the GPS block 2 and the correction value creation time of the pseudo distance correction value PRC and distance change rate correction value RRC included in the D-GPS data from the FM multiplex decoder 15. Based on the PRC and RRC, the pseudo-range correction value PRC in accordance with the current satellite reception time in the GPS block 2 is calculated (step C03), and then the operation returns to step C01 again. It is executed repeatedly.

  The pseudo distance correction value PRC in accordance with the current satellite reception time obtained in this way is sent to the GPS block 2 together with the distance change rate correction value RRC, and the distance change rate correction value RRC is further calculated as described above. Depending on the content, the frame period is used as a reference for continuously receiving VICS data.

  In this way, the FM tuner 14 simultaneously receives the reception frequency while performing the correction process at a frequency according to the degree that the current position data obtained from the GPS block 2 needs to be corrected using the distance change rate correction value RRC. Since VICS data is received continuously as much as possible by switching, it is assumed that the frequency differs between the broadcast radio wave that multiplexes D-GPS data and the broadcast radio wave that multiplexes VICS data. However, it is possible to automatically and appropriately switch this, and to continuously receive more necessary traffic information after always accurately recognizing the current position.

(Third embodiment)
A third embodiment in the case where the present invention is applied to an automobile navigation apparatus using GPS and FM data multiplex broadcasting will be described below with reference to the drawings.

  Note that the circuit configuration of the entire apparatus is basically the same as that shown in FIG. 1 and the external configuration of the remote control unit is basically the same as that shown in FIG. Is omitted.

  FIG. 18 mainly shows a detailed circuit configuration of the FM multiplex decoder 15. As shown in the figure, the FM multiplex decoder 15 includes a filter 15a, a PLL detector 15b, a synchronization detector 15c, a signal processor 15d, and a D-GPS detector. 15e and a timer 15f.

  The filter 15a extracts only the 76 KHz band of the subcarrier frequency multiplexed with digital data from the FM demodulated signal received by the FM antenna 4 and selected from the radio wave by the FM tuner 14, The output is sent to the PLL detector 15b.

  The PLL detection unit 15b performs delay detection on the output of the filter 15a based on the L-MSK method in accordance with the modulation degree of the stereo audio signal, demodulates the digital data, and then performs bit synchronization to perform digital synchronization. A clock synchronized with the digital data is reproduced by applying a PLL, and the demodulated digital data is sent to the synchronization detector 15c and the signal processor 15d, and the reproduced clock is sent to the synchronization detector 15c.

  The synchronization detector 15c generates a block synchronization signal synchronized with the block in the data by sampling the digital data with the recovered clock and detecting the BIC attached to the head of each block (packet) in the data. In addition, the frame synchronization signal is generated by detecting the change point of the BIC type, and the generated block synchronization signal and frame synchronization signal are output to the signal processing unit 15d.

  Under the control of the CPU 13, the signal processing unit 15d de-scrambles the digital data sent from the PLL detection unit 15b based on the block synchronization signal and the frame synchronization signal sent from the synchronization detection unit 15c. After error correction and CRC (Cyclic Redundancy Code) in the data are checked, the data is output to the CPU 13 outside the FM multiplex decoder 15 and also to the D-GPS detection unit 15e.

  The D-GPS detection unit 15e detects the presence or absence of error information data by D-GPS inserted in the first and second packets in one frame of data multiplex broadcast data, and at the time of detection, the D-GPS detection unit 15e The transmission of the reset signal is started, and the transmission is stopped when the reception is completed.

  The timer 15f counts a preset time after being reset by a reset signal from the FM multiplex decoder 15, and next time from when the time is up, that is, after the preset time has been counted. A reception frequency switching signal SW-PLL that is turned on during the time until the reset signal is input is sent to the CPU 13.

  The CPU 13 controls the frequency of the FM broadcast radio wave selected by the FM tuner 14 in response to the reception frequency switching signal SW-PLL from the timer 15f, and based on the corrected digital data obtained from the signal processing unit 15d. Execute the process.

  Next, the operation of the third embodiment will be described.

  Currently, VICS data is multiplexed and transmitted on FM broadcast radio waves having a frequency of 82.5 [MHz], while D-GPS data is multiplexed on FM broadcast radio waves having a frequency of 80.0 [MHz]. It is assumed that it has been sent.

  As shown in FIG. 19, the position of 80.0 [MHz] D-GPS error information data is fixed in advance in the first two packets (blocks) of each frame consisting of 272 block packets. In addition, since frame synchronization between the frequencies is not achieved, the reception timing is different between the multiplexed data frame of frequency 80.0 [MHz] and the multiplexed data frame of 82.5 [MHz]. .

  First, the CPU 13 searches the reception frequency by the FM tuner 14, and the error information data of the D-GPS is multiplexed on the FM broadcast radio wave having the frequency 80.0 [MHz], and the frequency 82.5 [MHz]. It is assumed that VICS traffic information data is multiplexed with FM broadcast radio waves.

  Thereafter, the CPU 13 first receives an FM broadcast radio wave having a frequency of 82.5 [MHz] by the FM tuner 14, and the error of the D-GPS obtained by the first two packets of each frame of digital data multiplexed on the FM broadcast radio wave. Information data is detected by the D-GPS detector 15e.

  When the reset signal is sent to the timer 15f from when the D-GPS detection unit 15e detects the D-GPS error information data until the reception is completed, the timer 15f is reset to the reset signal and starts measuring time, and the CPU 13 The reception frequency switching signal SW-PLL is set to “L” level. At this time, the CPU 13 simultaneously latches D-GPS error information data obtained from the signal processing unit 15d.

  In response to the reception frequency switching signal SW-PLL from the timer 15f becoming “L” level, the CPU 13 causes the FM tuner 14 to switch so as to receive FM broadcast radio waves having a frequency of 82.5 [MHz]. Reception of VICS traffic information data multiplexed on FM broadcast radio waves is started. Thereafter, until the reception frequency switching signal SW-PLL from the timer 15f becomes "H" level, that is, the next D again. -Continue to receive VICS traffic information data until the reception frequency is switched to 80.0 [MHz] to receive GPS error information data.

  FIG. 20 shows the operation in each of the above-mentioned parts centering on the period during which D-GPS error information data is received. FIG. 20 (1) shows the FM broadcast radio wave with a reception frequency of 80.0 [MHz]. Multiplexed D-GPS error information data, FIG. 20 (2) shows VICS traffic information data multiplexed on an FM broadcast radio wave with a frequency of 82.5 [MHz]. Indicates the number of the data packet, and the hatched portion indicates the missing data portion in reception.

  Normally, when switching the reception frequency, the time until the PLL is locked and the multiplexed digital data can be stably obtained by decoding is 10 to 20 [msec]. The larger the frequency difference between the two stations, the more time is required and it depends on the hardware configuration of the circuit, so here it is assumed that 60 [msec] is required until it is fully stable with sufficient margin. . Incidentally, since digital data is received over 5 seconds per frame, the time required per packet (block) (= 34 bytes) is 18 [msec].

  Therefore, the timer 15f is reset by the reset signal from the D-GPS detection unit 15e until the time 60 [msec] before the data of the D-GPS error information of the data packet 1 is received next. It is assumed that the time value is set in advance so as to time the interval.

  Accordingly, at the time 60 [msec] before the data of the D-GPS error information of the data packet 1 is received, the timer 15f times out as shown in FIG. When the signal SW-PLL becomes “H”, as described above, the CPU 13 changes the reception frequency at the FM tuner 14 to switch from the reception of traffic information data by VICS to the reception of error information data by D-GPS. Control.

  FIG. 20 (3) shows the state of the BIC clock of the digital data obtained with the reception of the traffic information data by VICS or the error information data by D-GPS, and the straight arrows can be received stably. The wavy arrow indicates an unstable state.

  After switching to reception of FM broadcast radio waves with a frequency of 80.0 [MHz], the error of the D-GPS of the data packets 1 and 2 is actually increased in a stable state as indicated by I in FIG. Receive informational data.

  When the D-GPS error information data of the data packet 1 is received and corrected by the signal processing unit 15d and then detected by the D-GPS detection unit 15e as shown in FIG. 20 (4). As shown in FIG. 20 (5), transmission of the k reset signal from the D-GPS detection unit 15e to the timer 15f is started.

  In the timer 15f, the reception of the error information data by the D-GPS of the data packet 2 is just finished. At the falling timing of this reset signal, the time measurement is reset and the time measurement is started again. The switching signal SW-PLL is set to the “L” level again, and the reception frequency at the FM tuner 14 is again switched to 82.5 [MHz] to receive the VICS traffic information data.

  When 60 [msec] elapses from this switching and the operation is stabilized as indicated by II in FIG. 3 (3), traffic information data by VICS can be actually received.

  Here, considering traffic information data by VICS, after receiving frequency is switched to receive error information data by D-GPS, the operation is actually stabilized and the data is received again, and then traffic information by VICS is again received. 12 packets (blocks) are lost as shown in FIG. 20 (2) until the operation is stabilized by switching the reception frequency for data reception.

  As shown in FIG. 19, the data multiplexed on the FM broadcast radio wave can be double-corrected in both the vertical and horizontal directions by parity within one frame. The information data can be used immediately after the correction processing in the horizontal direction and in units of blocks by the signal processing unit 15d. In addition, traffic information data by VICS is determined to be used after two corrections.

  FIG. 21 shows the process of correcting traffic information data by VICS, which is executed by the signal processor 15d using a frame memory for storing multiplexed data. First, as shown in FIG. For all the 272 packets excluding missing packets, error information data by D-GPS is inserted, and then the first correction is made in the horizontal direction, that is, in packet units.

  The error information data by D-GPS is used in the subsequent processing assuming that it is immediately effective as described above by the first horizontal correction processing.

  Therefore, in FIG. 1A, the missing portion LC indicated by hatching is a packet in which the operation by the PLL is unstable and the traffic information data by VICS cannot be received.

  Next, as shown in FIG. 21 (2), the correction process in the vertical direction of the data frame is performed as the second correction. Since this correction processing is performed in units of frames, the error information data by D-GPS, which is a different frame, is canceled and the correction processing is executed 34 times for each byte.

  Thereafter, the second horizontal correction is performed on the data frame subjected to the vertical correction as shown in FIG. In this case, correction processing is performed only on 190 packets excluding parity packets in all 272 packets in one frame.

  By executing the correction process a total of three times in this way, it is possible to restore the traffic information data by the VICS including the missing portion CL, and as a result, the FM tuner 14 and the FM multiplex decoder 15 are configured one by one. The error information data by D-GPS and the traffic information data by VICS can be received at the same time.

  In FIG. 21 (1), it has been described that error information data by D-GPS is inserted in the first horizontal correction process. This is a signal processing unit generally used in FM data multiplex broadcasting. This is because the correction process can be carried out using the frame memory provided in 15d as it is, and it is possible to carry out without inserting error information data by D-GPS. In addition, a memory for storing error information data by D-GPS and performing correction processing is separately required.

  Further, instead of the circuit configuration shown in FIG. 18, two FM tuners 141 and 142 having the same configuration as the FM tuner 14 are connected in parallel to the FM antenna 4 as shown in FIG. , 14b can be switched and selected by the switch 41 operating under the control of the CPU 13 and provided to the filter 15a of the FM multiplex decoder 15.

  In this case, for example, if the FM tuner 141 receives an FM broadcast radio wave with a reception frequency of 82.5 [MHz] and the FM tuner 142 receives an FM broadcast radio wave with a reception frequency of 80.0 [MHz], each tuner 141 , 142 can be obtained by switching the data multiplexed on the FM broadcast radio wave while continuing reception in a stable state.

  Therefore, the FM multiplex decoder 15 does not lose the reception of digital data multiplexed on the broadcast radio wave until the PLL operation is stabilized by switching the reception frequency with one FM tuner 14. Although the structure itself is only one, the missing portion of the data packet can be greatly reduced, the data correction processing can be reduced, and traffic information data by VICS can be obtained almost certainly.

  Further, instead of the circuit configuration of FIG. 22, the switch 41 is eliminated as shown in FIG. 23, and the filter 15a, PLL detection unit 15b, and synchronization detection unit 15c for obtaining digital data from the output of the FM tuner 142 are shown. It is also conceivable that a filter 15 a ′, a PLL detection unit 15 b ′, a synchronization detection unit 15 c ′, and a delay circuit 15 g having the same configuration as in FIG.

  In this case, for example, the FM tuner 141 receives an FM broadcast radio wave with a reception frequency of 82.5 [MHz], and the FM tuner 142 receives an FM broadcast radio wave with a reception frequency of 80.0 [MHz]. Circuit 15b and synchronization detector 15c for obtaining traffic information data by VICS, filter 15a ', PLL detector 15b', and synchronization detector 15c 'for obtaining error information data by D-GPS The D-GPS error information data obtained by the operation of the timer 15f is delayed and held in the delay circuit 15g by the delay circuit 15g. The phase difference from the data is absorbed.

  By doing so, although the circuit configuration in the FM tuner and the FM multiplex decoder becomes somewhat complicated, the lack of traffic information data by VICS corresponds to the minimum necessary error information data by D-GPS. It can be reduced to only two packets, and the burden of data correction processing can be reduced as much as possible, and traffic information data by VICS can be obtained reliably.

  In the circuit configuration of FIG. 23, the timer 15f and the delay circuit 15g are timed so that the traffic information data by VICS for two packets that are lost in the error information data processing by D-GPS avoids the parity packet. If the control is performed, the correction process can be performed more reliably and the traffic information data based on the accurate VICS can be restored.

  In addition, although FIGS. 18, 22 and 23 have been described with respect to the case where the hardware is used for the circuit configuration, it is possible to deal with only the processing by the software without using the circuit having such a configuration. It is.

  In this case, as shown in FIG. 24 (1), the CPU 13 switches and sets the reception frequency of the FM tuner 14 to receive error information data by D-GPS (step D01). After waiting for reception of error information data by D-GPS for two packets (step D02), the internal timer is reset (step D03), and this time FM is received to receive traffic information data by VICS. The receiving frequency of the tuner 14 is switched again and set (step D04).

  After that, while receiving traffic information data by VICS, it waits until the timer expires (step D05), and when it is determined that the timer has expired, the operation of returning to step D01 is repeatedly executed.

  At this time, as shown in FIG. 24 (2), the internal timer of the CPU 13 determines whether or not the time is up every predetermined clock (step E01). If not, the time count is counted up. (Step E02).

  As described above, the operation equivalent to the circuit having the configuration described in FIG. 18 can be realized by software, and it is possible to cope with the problem by replacing the storage medium storing the operation program of the device without replacing the navigation device. Can do.

  The method described in the first to third embodiments has been described as being stored in a CD-ROM mounted on the CD block 6 as a program to be executed by the navigation device. However, the present invention is not limited to this, and is applied to various storage media such as magnetic disks (floppy (registered trademark) disks, hard disks, etc.), optical disks (DVD, data MD, etc.), semiconductor memories, etc. It can also be applied to various devices by being transmitted through a communication medium, and can be applied not only to automobile-mounted navigation devices but also to data processing devices such as personal computers by mounting these various devices. It is also possible.

  In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

1 is a block diagram showing an overall circuit configuration according to a first embodiment of the present invention. The figure which shows the external appearance structure of the remote control unit which concerns on the embodiment. The figure which illustrates the display screen which concerns on the same embodiment. The figure which illustrates the display screen which concerns on the same embodiment. The figure which illustrates the display screen which concerns on the same embodiment. The figure which illustrates the display screen which concerns on the same embodiment. The figure which illustrates the display screen which concerns on the same embodiment. The flowchart which shows the content of the operation process which concerns on the same embodiment. The figure which shows the display mode of the present position symbol in the display screen which concerns on the embodiment. The figure which illustrates the display screen which concerns on the same embodiment. The figure which illustrates the display screen which concerns on the same embodiment. The block diagram which mainly shows the circuit structure of FM tuner concerning the 2nd Embodiment of this invention. The figure which shows the difference of the reception timing of the traffic information which concerns on the same embodiment, and error information. The figure which shows the content of the data of D-GPS which concerns on the embodiment. The figure which shows the content of the correction | amendment data set of each satellite given as said D-GPS data based on the embodiment. The flowchart which shows the content of the operation process which concerns on the same embodiment. The flowchart which shows the content of the operation process which concerns on the same embodiment. The block diagram which mainly shows the circuit structure of the FM multiplex decoder based on the 3rd Embodiment of this invention. The figure explaining operation | movement of the embodiment. 6 is a timing chart for explaining the operation of the embodiment. The figure explaining operation | movement of the embodiment. The block diagram which mainly shows the other circuit structure of the FM tuner and FM multiplex decoder which concerns on the embodiment. The block diagram which mainly shows the other circuit structure of the FM tuner and FM multiplex decoder which concerns on the embodiment. The flowchart which illustrates the content of the operation process at the time of implement | achieving with the software which concerns on the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... GPS antenna 2 ... GPS block 3 ... Graphic block 4 ... FM antenna 5 ... Key block 6 ... CD block 7 ... Monitor block 11 ... Flash EEPROM
12 ... RAM
13 ... CPU
14 ... FM tuner 14a ... FM receiver 14b ... demodulator 14c ... tuning controller 14d ... time corrector 15 ... FM multiplex decoder 15a ... filter 15b ... PLL detector 15c ... synchronization detector 15d ... signal processor 15e ... D- GPS detector 15f ... timer 15g ... delay circuit 16 ... CPU peripheral circuit gate array (G / A)
17 ... Graphic controller 18 ... Video RAM
20 ... Remote control unit 21 ... Remote control body case 22 ... Power switch 23 ... Power LED
26 ... FM DATA key 41 ... Switches 141, 142 ... FM tuner

Claims (6)

Map data storage means in which map data including road information is stored;
And positioning means for positioning a current position based on signals transmitted from multiple satellites,
Receiving means for receiving transmitted multiplexed in the broadcasting wave data,
A first reception control means for receiving the data of transportation information to the receiving means,
Second reception control means for receiving the data of the error information related to signals transmitted from the multiple satellites to the reception means,
After receiving either one of the traffic information data and the error information data multiplexed and transmitted on the broadcast radio wave by the first or second reception control means, the first or second reception control is performed. Third reception control means for changing the frequency by means to receive the other data;
Map data expansion means for reading out map data from the map data storage means based on the current position obtained by the positioning means and the error information data obtained by the second reception control means, and developing the map data as display data;
And changing means for changing the display data obtained by the map data expanding means using the data of the traffic information obtained in the first reception control means,
Display means for displaying the display data obtained by the changing means ,
The third reception control means, based on the update period of the content of the traffic information data or the value of the specific data in the correction data set of the satellite related to the error information data, A navigation apparatus characterized by setting a switching timing of a reception control means . The navigation according to claim 1, wherein the second reception control means receives data by performing a frequency search, and the frequency search is started from a reception frequency of the first reception control means. apparatus. The first and second reception control means receive data by performing a frequency search,
After the frequency search of the first and second reception control means is performed and the specified frequency information is secured, the tuning is controlled based on the frequency information without performing the frequency search again.
The navigation device according to claim 1. The data reception period of the first reception control means is configured to vary depending on the value of specific data in the satellite correction data set.
The navigation device according to claim 1. The data reception period of the second reception control means is a period for receiving only predetermined information.
The navigation device according to claim 1. Map data storage means in which map data including road information is stored;
Positioning means for positioning the current position based on signals transmitted from a plurality of satellites;
Receiving means for receiving data multiplexed with broadcast radio waves,
A control method for a navigation device comprising:
A first reception control step for causing the receiving means to receive traffic information data;
A second reception control step for causing the receiving means to receive error information data relating to signals transmitted from the plurality of satellites;
After receiving either one of the traffic information data and the error information data multiplexed and transmitted to the broadcast radio wave in the first or second reception control step, the first or second reception control is performed. A third reception control step of changing the frequency according to the step and receiving the other data;
A map data expansion step of reading out map data from the map data storage unit based on the current position obtained by the positioning unit and the error information data obtained in the second reception control step, and developing the map data as display data;
A change step for changing the display data obtained in the map data development step using the traffic information data obtained in the first reception control step;
A display process for displaying the display data obtained in this change process;
With
In the third reception control step, based on the update period of the content of the traffic information data or the value of the specific data in the correction data set of the satellite related to the error information data, Set the reception control process switching timing
A control method for a navigation device.

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