JP2000285384A - Reception device for car navigation device and its frequency switching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use road traffic information supplied from an information broadcast station by comparing the information sizes of respective reception frequencies and switching the detection frequency of a reception means into the reception frequency of the largest information size. SOLUTION: An information size update part 8 and an update history processing part 9 calculate the size of a data block stored in DRAM 5, generate the information size table of respective frequencies and respective mesh codes and store/update it in SRAM 6. When an error rate exceeds a threshold ε for prescribed time in an error rate comparison/switching part 12 and a switching judgment part 13, the detection frequency of a PLL frequency demodulator 3 is switched to the frequency of an FM broadcast station which is adjacent to a selected FM broadcast station and whose error rate is the smallest. An information size comparison switching part 11 and the switching judgment part 13 compare the information sizes of the respective frequencies of a mesh area to which the present position of a self-vehicle belongs and the detection frequency of the PLL frequency demodulator 3 is switched to the frequency of the largest information size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a car navigation system, and more particularly to a receiving system for receiving road traffic information from each information broadcasting station of a road traffic information system. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus for automatically selecting an information broadcasting station that provides the most traffic information around the position of a vehicle among stations, and a frequency switching method thereof.

[0002]

2. Description of the Related Art In recent years, the operation of a road traffic information system which provides road traffic information of each region to a running automobile by using FM multiplex broadcasting or the like has been started. Car navigation systems that receive and display information such as traffic congestion information, accident information, and construction information on a map and provide optimal guidance have been researched and developed.

[0003] In such a road traffic information system, an area on a map is divided into mesh areas, and information broadcasting stations in various places provide information on mesh areas belonging to a service area. Since each information broadcasting station broadcasts by radio waves of different frequencies, in order to receive road traffic information with a moving car, every time the service area of the information broadcasting station changes, a new information broadcasting station is selected. It is necessary to track by doing again. In particular, when traveling at high speed or traveling near the boundary of the service area of each information broadcasting station, it is necessary to perform frequent tracking, which is inconvenient for the user. There is a need for a car navigation device receiving device that can automatically perform such tracking.

A conventional receiving apparatus is disclosed in Japanese Patent Laid-Open No. 6-27.
Japanese Patent No. 4792 (hereinafter referred to as "A") states that "an automobile having a receiving means for receiving information supplied separately from a predetermined information broadcasting station for each area within the receivable area. The vehicle according to claim 1, further comprising: vehicle position detecting means for detecting a traveling position of the vehicle; and memory means for storing the area information near the traveling position detected by the vehicle position detecting means. An information storage device "is disclosed.

[0005] The information storage device for a vehicle disclosed in the above publication A stores information in a mesh area which has traveled once, and uses information stored in the past when traveling in the same mesh area again. It was that.

[0006]

However, the above-mentioned conventional receiving apparatus cannot cope with ever-changing road traffic information such as traffic congestion and accidents, and the provided road traffic information can be effectively used. Had the problem of not being able to do so.

Therefore, in order to perform automatic tracking in response to such time-varying road traffic information, an error rate at the time of receiving the information broadcast signal being received at each time point is detected, and the error rate is detected. If the time exceeding a certain threshold continues for a predetermined time or more, it is determined that the vehicle has left the service area of the information broadcasting station, and another information broadcasting station having a good reception condition is automatically selected. Can be considered.

However, such automatic tracking has the following problems.

(1) If the vehicle travels in a place where the reception condition of radio waves is poor such as a tunnel or behind a shield while the vehicle is traveling, it is determined that the vehicle has gone out of the service area of the information broadcasting station by mistake.
Switching of the frequency of the information broadcasting station is performed. Since road traffic information is provided at time intervals of 1 to 5 minutes, once frequency switching is performed, it takes time to accumulate information,
Time-varying road traffic information cannot be used effectively.

(2) Conversely, if it is assumed that the frequency switching is not performed unless the error rate continues for a predetermined time or more and exceeds a certain threshold, even if the user goes out of the service area of the information broadcasting station, In the case where the reception condition is improved intermittently, the frequency is not easily switched and the information of the information broadcasting station outside the service area is continuously received, so that the road traffic information can be used effectively. Disappears.

(3) In the downtown area or the like, the service area of each information broadcasting station often intersects. In such a case, if the information broadcasting station having a good reception state is automatically used for tuning, the total It takes time to search for hits, and it is not possible to effectively use time-varying road traffic information.

(4) When traveling on a bridge over the sea, for example, the reception condition of an information broadcasting station on the other side of the sea may be good. In such a case, the frequency is switched. Then, the information of the information broadcasting station outside the service area is received, so that the road traffic information cannot be effectively used.

(5) In the vicinity of the boundary of the service area of each information broadcasting station, road traffic information provided by the information broadcasting station located ahead in the traveling direction is necessary. For that purpose, information broadcasting located ahead in the traveling direction is required. You need to select a station. However, if the reception state of the information broadcasting station located in the rear in the traveling direction which has been continuously received until then does not deteriorate, frequency switching is not performed, and useful road traffic information is provided from the receivable information broadcasting station. in spite of,
Road traffic information cannot be used effectively.

[0014] The present invention solves the above-mentioned conventional problems, and it is possible to switch the selection of an information broadcasting station in accordance with the reception state of the broadcast at the own vehicle position, and further to enable the information broadcast receivable at the own vehicle position. It is possible to automatically select the information broadcasting station that provides the largest amount of road traffic information in the vicinity of the vehicle position among the stations, and effectively use the road traffic information provided by the information broadcasting station. An object of the present invention is to provide a receiving device of a car navigation device that can be used.

Further, the present invention solves the above-mentioned conventional problems, and it is possible to switch the selection of an information broadcasting station in accordance with the broadcast reception state at the own vehicle position, and further to enable reception at the own vehicle position. Among the information broadcasting stations, it is possible to automatically select the information broadcasting station that provides the largest amount of road traffic information near the vehicle position, and the road traffic information provided by the information broadcasting station can be automatically selected. It is an object of the present invention to provide a frequency switching method of a receiving device of a car navigation device that can be effectively used.

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a receiving device of a car navigation device according to the present invention is a receiving device of a car navigation device for receiving information from each information broadcasting station of a road traffic information system. Receiving means for receiving information on each mesh area provided by radio waves from the information broadcasting station, own vehicle position detecting means for detecting the own vehicle position, information storage means for storing information on each mesh area, An information size storage unit for storing an information size, which is a size of information for each mesh area and each reception frequency; and information for each mesh area provided by the information broadcasting station received by the reception unit, stored in the information storage unit for storage. The information size of the information for each mesh area stored in the information storage means and registered in the information size storage means. Or, the information size registration means to be updated is compared with the information size of each reception frequency read from the information size storage means of the mesh area to which the own vehicle position detected by the own vehicle position detection means belongs, and the detection frequency of the reception means is compared. And an information size comparison switching means for switching to a reception frequency having the largest information size.

According to this configuration, it is possible to switch the selection of the information broadcast station in accordance with the broadcast reception state at the own vehicle position. Car navigation system that enables automatic selection of information broadcasting stations that provide the largest amount of road traffic information, and that makes it possible to effectively use the road traffic information provided by information broadcasting stations An apparatus for receiving a device can be provided.

Further, according to the frequency switching method of the receiving device of the car navigation device of the present invention, a receiving means for receiving information of each mesh area provided by radio waves from each information broadcasting station of the road traffic information system; Vehicle position detection means for detecting the information of each mesh area, information storage means for storing information of each mesh area, and information size storage means for storing an information size which is the size of information for each mesh area and each reception frequency. A method for switching the frequency of a receiving device of a car navigation device, comprising: receiving information of each mesh area provided by an information broadcasting station by a receiving means, storing and storing the information in an information storage means; Acquire the information size of the stored information for each mesh area, and register the information size to be registered or updated in the information size storage means. Procedure, the own vehicle position is detected by the own vehicle position detecting means, the information size of each reception frequency of the mesh area to which the own vehicle position belongs is read from the information size storage means, the information size of each reception frequency is compared, and And an information size comparison switching procedure for switching the detection frequency to the frequency having the largest information size.

With this configuration, it is possible to switch the selection of the information broadcasting station in accordance with the broadcast reception state at the own vehicle position. Car navigation system that enables automatic selection of information broadcasting stations that provide the largest amount of road traffic information, and that makes it possible to effectively use the road traffic information provided by information broadcasting stations A method for switching a frequency of a receiving device of the device can be provided.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to achieve this object, a receiving device for a car navigation device according to a first aspect of the present invention is a car navigation device for receiving information from each information broadcasting station of a road traffic information system. A receiving device,
Receiving means for receiving information on each mesh area provided by radio waves from an information broadcasting station; own vehicle position detecting means for detecting the own vehicle position; information storage means for storing information on each mesh area; and each mesh area Information size storage means for storing an information size that is the size of information for each reception frequency; and information for storing and accumulating information of each mesh area provided by the information broadcasting station received by the reception means in the information storage means. Storage means, information size registration means for acquiring the information size of the information for each mesh area stored in the information storage means and registering or updating the information size in the information size storage means, and the vehicle position detected by the vehicle position detection means The information size of each reception frequency read from the information size storage means of the mesh area to which the Information size comparison switching means for switching the largest reception frequency of the noise is obtained by a configuration with a.

With this configuration, the following operation is obtained.

(1) The information of each mesh area received by the receiving means is sequentially stored in the information storage means by the information storage means. The information size registration unit acquires the information size of the information for each mesh area stored in the information storage unit, and registers or updates the information size in the information size storage unit. In parallel with this, the information size comparison switching means acquires the own vehicle position detected by the own vehicle position detection means, and reads out the information size of each reception frequency of the mesh area to which the own vehicle position belongs from the information size storage means. Then, the information size of each reception frequency of the mesh area to which the read vehicle position belongs is compared, and the detection frequency of the reception means is switched to the reception frequency having the largest information size (the largest amount of information).

(2) Since the detection frequency is switched to the broadcast station having the largest amount of information at the own vehicle position by the information size comparing and switching means, the information broadcast stations which can be received at the own vehicle position are always in the vicinity of the own vehicle position. It is possible to automatically select an information broadcasting station providing the largest amount of road traffic information.

According to a second aspect of the present invention, there is provided the receiving device of the car navigation device according to the first aspect, wherein the state in which the error rate at the time of receiving the information of the receiving means is equal to or more than the predetermined threshold is equal to or more than the predetermined time When the continuation is continued, an error rate comparison switching means for switching the detection frequency of the receiving means to a frequency of an information broadcasting station other than the information broadcasting station selected at that time is provided.

With this configuration, the following operation is obtained.

(1) The error rate comparison / switching means determines that the user has gone out of the service area when the error rate at the time of receiving the information of the receiving means has continued for a predetermined time or more, and The detection frequency of the receiving means is switched to the frequency of an information broadcasting station other than the information broadcasting station currently selected.

(2) When a broadcasting station stops broadcasting,
If the frequency cannot be received in the mesh area where the vehicle is located, another broadcast station can be automatically selected.

(3) Since the information size comparison and switching means switches to the detection frequency of the broadcast station having the largest amount of information at the position of the vehicle, the error rate comparison and switching means switches the frequency only when the reception becomes completely impossible. Just do it. Therefore, when the error rate comparison and switching means determines that the vehicle has gone out of the service area of the information broadcasting station, a longer time (determination time) in which the error rate is equal to or higher than the predetermined threshold is set. This prevents the frequency of the information broadcasting station from being erroneously switched when the vehicle travels in a place where reception of radio waves is poor, such as a tunnel or behind a shield while the vehicle is traveling.

Here, when the error rate comparison switching means determines that the own vehicle has gone out of the service area of the information broadcasting station,
It is preferable that the time during which the error rate is equal to or higher than the predetermined threshold is continued (determination time) is set to 4 minutes to 10 minutes. If the time is shorter than 4 minutes, there is a tendency that the frequency of the information broadcasting station is erroneously switched when the vehicle is traveling and traveling in a place where reception of radio waves is poor such as behind a tunnel or a shield. Since one piece of mesh information may be composed of a plurality of data groups, if one does not wait for data to be sufficiently prepared, the information is registered in a small size, and there is a tendency to automatically track another frequency. If the frequency is longer, the broadcast station stops broadcasting, and the frequency cannot be received in the mesh area where the vehicle is located. Because it cannot be obtained.

According to a third aspect of the present invention, there is provided the receiving device of the car navigation device according to the second aspect, wherein the error rate comparison switching means or the information size comparison switching means switches the detection frequency of the receiving means, and then the receiving means is switched. In the case where the information is not received, there is provided a switching determining means for returning the detection frequency of the receiving means to the original frequency.

With this configuration, the following operation is obtained.

(1) The switching determination means checks whether or not the receiving means is receiving information after the error rate comparison switching means or the information size comparison switching means switches the detection frequency of the receiving means. When the receiving means has not received the information, the detection frequency of the receiving means is returned to the original frequency.

(2) When the information broadcasting station selected after the switching has stopped broadcasting, it is prevented that the broadcasting station is selected.

The invention described in claim 4 is the first to third aspects of the present invention.
Wherein the error rate at the time of receiving information of the receiving means is equal to or less than a predetermined threshold value after the information storing means starts storing information in the information storing means. When the reception time of the information has reached a predetermined time, the information size of the information for each mesh area stored in the information storage means is acquired and registered or updated in the information size storage means.

With this configuration, the following operation is obtained.

(1) It is possible to prevent the information size of information received in a poor reception state due to the presence of a shielding object such as a building from being registered or updated in the information size storage means,
By registering or updating a small information size, it is possible to prevent the information size comparison switching unit from erroneously making a determination and switching the frequency.

Here, it is preferable that the integrated value of the reception time in which the information size registration means stores the error rate is set to 2.5 to 10 minutes. If less than 2.5 minutes,
Since the receiving time of the receiving means is not sufficient, the information size tends to be updated with a small information size. If the receiving time is longer than 10 minutes, the receiving time of the receiving means is too long and the user waits while receiving the same information many times. This is because the information size registered in the information size storage unit is not easily registered or updated, and there is a tendency that the information size comparison switching unit does not select the optimal information broadcasting station.

The invention described in claim 5 is the invention according to claims 1 to 4
The data receiving device of the car navigation device according to any one of the above, wherein the receiving frequency, the mesh code of the mesh area, the previous information size, and the information size of the last day are stored in the information size storage means as one unit. Comprises an information size table in which a plurality of units are registered, and information size table updating means for updating the previous information size of each of the information size tables to the information size of the last day when a predetermined time has elapsed. The registering means, if the information size of the last day corresponding to the information size is registered in the information size table before registering or updating the information size in the information size table, the information size is larger than the information size of the last day. If it is larger, update the information size of the last day to the information size, and save the information size before registering the information size in the information size table. If the information size of the last day corresponding to the information size is not registered in the size table, the information size is newly registered as the information size of the last day in the information size table. When the information size is read out by the means, the previous information size is compared with the information size of the last day, and the larger one is read out as the information size.

With this configuration, the following operation is obtained.

(1) The information size of each reception frequency and each mesh code is registered or updated to the information size of the last day corresponding to the same reception frequency and each mesh code in the information size table. When updating the information size of the last day registered in the information size table, it is not updated if the information size to be updated is smaller than the information size of the last day already registered in the information size table . Therefore, in the information size table, the maximum information size of each reception frequency and each mesh code in the day is registered. When a predetermined time has elapsed, the information size table updating means updates the previous information size of each of the information size tables to the information size of the last day. The information size comparison switching means includes:
When reading the information size from the information size storage means in order to compare the information size of each reception frequency of the mesh area to which the own vehicle position belongs, the previous information size is compared with the information size of the last day, whichever is larger. Is read as the information size, the information size of each reception frequency is compared, and the detection frequency of the receiving means is switched to the reception frequency having the largest information size.

(2) When the information broadcasting station temporarily stops broadcasting and 0 is registered as the information size of the last day corresponding to the frequency and the mesh code in the information size table, or the reception condition is accidentally bad. Even if the information size of the last day corresponding to the frequency and the mesh code or a smaller value is registered because the vehicle has traveled in the area, the information size comparison switchover means switches the previous information size and the information size of the last day. Since the larger one is compared and read out as the information size and compared, the detection frequency of the receiving means is switched, so that the accuracy of selecting an information broadcasting station is improved and the road traffic information can be effectively utilized. .

According to a sixth aspect of the present invention, there is provided the receiving device of the car navigation device according to the fifth aspect, wherein the error rate comparison switching means or the information size comparison switching means switches the detection frequency of the receiving means, and then the receiving means is switched. When no information is received, the previous information size is updated to the last day information size in the unit corresponding to the reception frequency after switching of the information size table and the mesh area to which the own vehicle position belongs at that time, and the last day And / or when the receiving means does not receive information when the update history processing unit registers the information size in the information size table, the current reception frequency of the information size table and the time point The previous information size is updated to the last day information size in the unit corresponding to the mesh area to which the own vehicle position belongs in The last information size day is obtained by the structure having the zero clear processing means for updating the zero.

With this configuration, the following operation is obtained.

(1) The zero clear processing means fails in automatic tracking when the receiving means has not received information after the detection frequency of the receiving means has been switched by the error rate comparison switching means or the information size comparison switching means. In the unit corresponding to the reception frequency after the switching and the mesh area to which the own vehicle position at that time belongs,
The information size of the last day is updated to the information size of the last day, and the information size of the last day is updated to 0. And / or if the receiving means does not receive the information when the update history processing unit registers the information size in the information size table, it is determined that the information broadcasting station has stopped broadcasting, and In the unit corresponding to the reception frequency and the mesh area to which the own vehicle position belongs at that time, the previous information size is updated to the last day information size and the last day information size is updated to zero.

(2) When the information broadcasting station stops broadcasting,
By setting the information in the information size table to zero, the data size of the broadcasting station is prevented from remaining in the information size table indefinitely. It is possible to prevent the broadcast station from being erroneously selected.

According to a seventh aspect of the present invention, there is provided a method for switching a frequency of a receiving device of a car navigation device, comprising: receiving means for receiving information of each mesh area provided by radio waves from each information broadcasting station of a road traffic information system. A vehicle position detecting means for detecting a vehicle position, an information storing means for storing information of each mesh area, and an information size storing means for storing an information size which is a size of information for each mesh area and each reception frequency. And a frequency switching method of a receiving device of a car navigation device comprising: an information storage procedure of receiving information of each mesh area provided from an information broadcasting station by a receiving means, storing and storing the information in an information storage means, The information size of the information for each mesh area stored in the information storage means is acquired and registered or updated in the information size storage means. The size registration procedure, the vehicle position is detected by the vehicle position detection means, the information size of each reception frequency of the mesh area to which the vehicle position belongs is read from the information size storage means, and the information size of each reception frequency is compared and received. And an information size comparison switching procedure for switching the detection frequency of the means to the frequency having the largest information size.

According to this configuration, the detection frequency is switched to the broadcasting station having the largest amount of information at the position of the own vehicle.
Of the information broadcasting stations that can always be received at your vehicle location,
The effect is obtained that it is possible to automatically select the information broadcasting station that provides the largest amount of road traffic information near the own vehicle position.

According to an eighth aspect of the present invention, there is provided the frequency switching method of the receiving device of the car navigation apparatus according to the seventh aspect, which is performed in parallel with the information storage procedure, the information size registration procedure, and the information size comparison switching procedure. If the state in which the error rate at the time of receiving the information of the receiving means is equal to or higher than the predetermined threshold continues for a predetermined time or more, the information broadcasting station other than the information broadcasting station which is currently selecting the detection frequency of the receiving means. And an error rate comparison switching procedure for switching to the station frequency.

With this configuration, the following operation is obtained.

(1) When a broadcasting station stops broadcasting,
If the frequency cannot be received in the mesh area where the vehicle is located, another broadcast station can be automatically selected.

(2) In the information size comparison switching procedure, the detection frequency is switched to the broadcast station having the largest amount of information at the own vehicle position. Therefore, in the error rate comparison switching procedure, the frequency is switched only when the reception becomes completely impossible. Should be performed. Therefore, when it is determined that the own vehicle has gone out of the service area of the information broadcasting station, it is possible to set a longer time (determination time) during which the error rate is equal to or higher than the predetermined threshold, and the own vehicle can be set. This prevents the frequency of the information broadcasting station from being erroneously switched when traveling in a place where the reception condition of radio waves is poor, such as a tunnel or behind a shield during traveling.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1) The receiving apparatus according to the present embodiment uses a VICS (Vehicle Information and Comm) transmitted from an FM broadcast station as an information broadcast station by FM multiplex broadcasting.
unication Syatem (Road traffic information communication system) This is a receiver equipped with a car navigation system that receives and reproduces information, and selects the broadcast station that is transmitting the best information at the position of the vehicle as the vehicle moves. The detection frequency is automatically switched by the frequency switching method.

In FM multiplex broadcasting, VICS information is transmitted as one or a plurality of data groups every 1 to 5 minutes. The data group further includes a plurality of data blocks, and the VICS information is carried as a data block in a data packet and transmitted as a multiplex signal of FM radio waves. The receiving apparatus according to the present embodiment reproduces data blocks after performing error correction on received data packets, and further constructs a data group by connecting the data blocks in a predetermined order.
S information is reproduced. At this time, an optimum FM broadcast station is selected based on an error rate at the time of reception and the amount of information around the own vehicle position included in the received VICS information. is there.

FIG. 1 is a block diagram showing the configuration of the receiving apparatus according to the first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a receiver for receiving FM radio waves.
Antenna 2 detects the received FM signal and selects the station.
A detection channel selection section that outputs a detected signal and 3 is an FM reception signal
, And the frequency signal for detection of the detection tuner 2 is
Output PLL frequency demodulator (Phase-Locked Loop freq
uency demodulator phase locked loop frequency demodulator), 4
Is a signal obtained by decoding the FM reception signal output from the detection tuner 2
Outputs packets and measures error rate during decoding
DARC (Data
 Radio Channel) decoder, 5 is data group (later)
(Dynamic Random Access Memo)
ry dynamic constant speed call storage device), 6 is each mesh area
Stores the size of the data group corresponding to each frequency
SRAM (Static Random Access Memory
7 is a DARC decoder 4
Create a data group from the data packets to be output and
Data group stored in RAM 5 or stored in DRAM 5
8 is a DARC database.
Error rate P output by coder 4_errFor a certain period of time
Reception time integrated value S_errIs a constant threshold S_maxWhen
Is the current frequency f stored in the SRAM 6_x,mesh
Area y (Mesh code M_y) Corresponding dataglu
Loop size (hereinafter, referred to as information size) S₀(F_x,
M_y) And information size update to output information size update request
And 9, the information size S from the information size updating unit 8₀(F_x,
M_y) And the information size update request is input
S₀(F_x, M_y) And the current stored in the SRAM 6
Current frequency f of mesh area y_xInformation corresponding to
Size S₁(F_x, M_y) And S₁(F_x, M_y) <S
₀(F _x, M_yIn the case of), the information stored in the SRAM 6
Size S₁(F_x, M_i) Is the current information size S₀(F_x,
M_y), The update history processing unit 10 updates the frequency f_x, Me
Information size S corresponding to the hash area y₁(F_x, M_y)
When there is a read request The last time stored in the SRAM 6
Data group size S₁(F_x, M_y) And the last day
Data group size S_Two(F_x, M_y) And compare
Whichever is larger, information size S_Three(F_x, M_yOut as)
The information size read processing unit 11 to be input
Of the current location mesh area y input from the
Report size S _Three(F_x, M_y) And the frequency f of the surrounding broadcasting station
_i(I の x) Information size of current mesh area y
S_Three(F_i, M_y) And S_Three(F_x, M_y) <S
_Three(F_i, M_y), The frequency f_iSwitch request S2 to
Output information size comparison switching section, 12 is DARC decoder
Error rate P output by DA4_errIs a predetermined time T_Two(Example
If the value is smaller than the threshold ε continuously for
Frequency f of another broadcasting station including the flash area y_i(I is free
A switching request S1 to an appropriate broadcasting station other than the transmission station x is output.
Error rate comparison switching unit 13 is an information size comparison switching unit
Switching request S1 from the unit 11 or the error rate comparison switching unit 12.
Or, when S2 is input, the set frequency of the PLL frequency demodulator 3 is set.
The wave number to the current frequency f_xTo frequency f_iSwitch to
When the frequency does not match (when phase synchronization cannot be performed)
Alternatively, a data packet is output from the DARC decoder 4
If not, the frequency is set based on the set frequency of the PLL frequency demodulator 3.
Frequency f _xThe switching determination unit 14 returns to the current date and time data.
A clock that outputs data, 15 is date and time data that is output by the clock 14
If the date of the data has changed, the previous
Information size S_Two’(F_j, M_i) Value is the last day's information
Is S_Two(F_j, M_i) To update the information size
Table update section 16 is input from information size update section 8
Information size S₀(F_x, M_y) Is 0 or PLL circumference
If tracking could not be performed when switching the frequency of the wave number demodulator 3
Information size S stored in the SRAM 6₁(F_x,
M_y) Is zero-cleared, and 17 is GP
A GPS antenna that receives navigation radio waves from the S satellite,
Reference numeral 18 denotes a GPS which measures and outputs the position of the own vehicle by GPS.
The receiver 19 receives the position information output from the GPS receiver 18.
Measures the coordinates (latitude / longitude, etc.) of the vehicle position based on the notification signal
A vehicle position detecting unit for detecting the vehicle position;
Map composed of OM and CD-ROM drive, etc.
It is a map information storage unit that stores information.

[0057] The PLL frequency demodulator 3 outputs a detection frequency signal of a set predetermined frequency to the detection tuner 2. The detection tuning section 2 detects and outputs an FM radio wave transmitted from the FM broadcast station received by the receiving antenna 1 by FM multiplex broadcasting. The detection frequency setting at this time is P
This is performed by a detection frequency signal output from the LL frequency demodulator 3. The FM reception signal received by the detection channel selection unit 2 is demodulated by the DARC decoder 4, and the multiplexed signal is separated and demodulated. Next, the DARC decoder 4
Detects the block synchronization of the multiplexed signal, performs error correction using a CRC and a parity code, and outputs the packet to the data group construction unit 7 as a packet.

The DARC decoder 4 measures a block synchronization error, a horizontal correction error, and a vertical correction error when decoding the FM reception signal, and outputs the measured error as required. Here, the block synchronization error indicates an error when the DARC decoder 4 cannot detect the first block identification code BIC1 to BIC4 of each packet. If a block synchronization error occurs, the contents of the packet cannot be reproduced. Also, the horizontal correction error is determined by the cyclic code (C
RC), and a vertical correction error is an error that occurs when a frame in which an error cannot be corrected due to a horizontal correction error is further corrected using a parity packet.

Each of the information size updating unit 8, the information size comparison switching unit 11, and the error rate comparison switching unit 12 includes a timer for counting time inside.

GPS antenna 17 and GPS receiver 18
Receives navigation radio waves transmitted wirelessly from four GPS satellites to the ground and outputs them to the vehicle position detection unit 19. The own-vehicle position detection unit 19 determines the GP based on the transmission time of the radio wave included in the navigation radio wave, orbit information around the earth, and the arrival time of the navigation radio wave.
The distance from the S artificial satellite to the own vehicle is measured, and the position of the own vehicle is detected from the coordinates of the intersection of the spherical surfaces around each GPS artificial satellite.

In this embodiment, the receiving means includes a receiving antenna 1, a detection channel selecting unit 2, a PLL frequency demodulator 3,
The DARC decoder 4 is provided, and the vehicle position detecting means is composed of a GPS antenna 17, a GPS receiver 18, a vehicle position detecting section 19, and a map information storage section 20, and the information storage means is composed of a DRAM 5. The information size storage means is constituted by the SRAM 6, the information storage means is constituted by the data group construction section 7, and the information size registration means is constituted by the information size update section 8 and the update history processing section 9. The information size comparison and switching means is constituted by an information size reading processing unit 10 and an information size comparison and switching unit 11, the error rate comparison and switching means is constituted by an error rate comparison and switching unit 12, and the switching judgment means is switched. The information size table updating means includes a clock 14,
An information size table updating unit 15;
The zero clear processing means includes a zero clear processing unit 16.

Next, the configuration of each data processed in the receiving apparatus of the present embodiment will be described.

FIG. 2 is a diagram showing a data format of a data frame.

As shown in FIG. 2, the data frame is 1
The frame is composed of a packet for transmitting data of 190 blocks and a parity packet of 82 blocks. Packets for transmitting data start from the beginning.
16-bit block identification code BIC, 176-bit data packet, 14-bit CRC (Cyclic Redunda
ncy Check), which is composed of an 82-bit horizontal parity code. The block identification code BIC is a code indicating the type of each packet. The data packet is data on which information to be transmitted such as VICS information is loaded.
Is a code for performing error detection using a cyclic code,
The horizontal parity code is horizontal parity information in one frame. The parity packet includes a 16-bit block identification code BIC and a 190-bit parity from the head. The parity packets are distributed in data frames to prevent burst errors. A parity packet is a packet in which a vertical parity code of a plurality of data frames is placed,
For example, parity 1 in FIG.
Parity information of data packet 5 and CRC and parity 2 are data packets of data packets 16 and 17 and parity information of CRC.

FIG. 3 is a diagram showing the data format of the data packet shown in FIG.

As shown in FIG. 3, the data packet is
It consists of a 32-bit prefix and a 144-bit data block (in the case of character / graphic information data) or a 16-bit prefix and a 160-bit data block (in the case of data such as time information and broadcast station name). Further, the prefix includes a service identification, a decoding identification, an information end flag, an update flag, a data group number, and a data packet number.

FIG. 4 is a diagram showing a data format of a data group.

A data group is reconstructed data constituted by joining data blocks of a received data frame in a predetermined order, and as shown in FIG. A flag, a page number, a mesh number, upper 8 bits of map coordinates X, upper 8 bits of map coordinates Y, and remaining message data are arranged in this order. A mesh code is composed of two codes of the upper 8 bits of the map coordinates X and the upper 8 bits of the map coordinates Y.

FIG. 5 is a diagram showing a data structure stored in the SRAM.

The size (information size) of the data group restored from the received data frame is stored in the SRAM 6.
Are classified and stored for each reception frequency and each mesh code. Specifically, as shown in FIG. 5, the mesh code, the reception frequency, the previous information size, the information size of the last day, and the date when the information size of the last day were updated are defined as one unit data set. A plurality of units of this data set are stored as an information size table. As described later, when a data frame is received and a data group is obtained, the reception size of the data group in the information size table and the information size of the last day corresponding to the mesh code are set to the information size of the obtained data group. Be updated. When the date output by the clock 14 changes, the previous information size of each reception frequency and each mesh code in the information size table is updated to the information size of the last day.

In the receiving apparatus of the present embodiment configured as described above, the frequency switching method will be described below.

In the frequency switching method according to the present embodiment, the data is reconstructed by constructing a data group from the data packets output from the DARC decoder 4 in the data group constructing unit 7, and the data is sequentially stored in the DRAM 5.
Update. At the same time, the information size updating unit 8
The update history processing unit 9 calculates the size of the data block stored in the DRAM 5, creates an information size table for each frequency and each mesh code,
Stored / updated in M6. On the other hand, in parallel with this, the error rate comparison switching unit 12 and the switching determination unit 13
When the error rate output from the RC decoder 4 exceeds a predetermined threshold ε for a predetermined time (for example, 6 minutes),
At that time, the detection frequency of the PLL frequency demodulator 3 is switched to the frequency of the FM broadcast station having the lowest error rate among the FM broadcast stations selected and the FM broadcast station adjacent to the FM broadcast station. Further, in parallel with this, the information size comparison switching unit 1
1. The switching determination unit 13 compares the information size of each frequency of the mesh area to which the current vehicle position belongs stored in the SRAM 6 and switches the detection frequency of the PLL frequency demodulator 3 to the frequency having the largest information size. Can be It should be noted that when the broadcast station stops broadcasting, for example, a zero clear process for clearing the size stored in the SRAM 6 to zero,
A date change process for sequentially updating old data out of the data stored in the RAM 6 is also performed.

The data group construction and storage / update to the DRAM, the update of the SRAM data, the request for switching the detection frequency by comparing the error rate, the request for switching the detection frequency by comparing the information size, and the switching of the detection frequency will be described in detail below. Will be described.

First, data group construction and storage / update in the DRAM will be described. The construction of the data group and the storage / update in the DRAM are performed in the data group construction unit of FIG.

FIG. 6 is a flowchart showing the operation of the data group construction unit.

First, when a packet as shown in FIGS. 2 and 3 is input from the DARC decoder 4 (S1), the data group construction unit 7 constructs a data frame according to the number of each received packet. Next, it is determined whether or not the construction of the data frame has been completed (S2).
It returns to 1 and waits for input of a packet again.

When the construction of the data frame is completed in step S2, the data group construction section 7 takes out and connects the data packets contained in the data frame to construct frame data (S3). Further, a data group is constructed with the same data group number in the frame data as one data group (S4). The data group end code is included in the constructed data group. If the data group end code indicates continuation of the data group (S5), the process returns to step S1 again to continue the construction of the data group. .

If the data group end code indicates the end of the data group in step S5 (S5), the data group construction unit 7 determines whether or not a data group of the same mesh code is stored in the DRAM 5. If the data group of the same mesh code is not stored in the DRAM 5 (S6), the constructed data group is newly added to the DRAM 5 (S6).
(S7). In step S6, the DRAM
When the data group of the same mesh code is stored in the DRAM 5, the data group of the same mesh code stored in the DRAM 5 is updated to the constructed data group (S8).

When the above operation is completed, the data group construction unit 7 returns to the operation of step S1 again, and
The storage / update processing of the data group to the server is continued.

As described above, the data group construction unit 7
Constructs a data group from the data frames output from the DARC decoder 4 and stores / updates the data group in the DRAM 5 to keep accumulating the latest data group in the DRAM 5.

Next, the data update processing of the SRAM will be described. The data update processing of the SRAM is performed in the information size update unit 8 of FIG.

FIG. 7 is a flowchart showing the processing operation of the information size updating unit.

First, the information size update unit 8 resets the value of the reception time integrated value variable S _err stored therein to 0,
The count value t ₁ of the internal timer is reset to 0 to start counting (S10).

Next, the information size updating unit 8 sends an error rate output request to the DARC decoder 4 and acquires the error rate _Perr from the DARC decoder 4 (S1).
1). Next, when the error rate P _err is smaller than the fixed threshold ε ₁ (S12), 1 is added to S _err (S1).
3). In other words, the number of timings when the reception status is good (that is, the reception time when the reception status is good) is obtained as the reception time integrated value Serr.

Next, the time value t of the timer₁Is the specified time
Interval T₁It is determined whether or not the time is ₁Is the specified time
T₁In the following cases, the process returns to step S11.

In step S14, if the time value t ₁ is equal to or longer than the predetermined time T ₁ (for example, 2 minutes 30 seconds),
Information size updating unit 8, receives the time integrated value S _err it is determined whether more than a predetermined threshold value S _{m ax} (S15), if the reception time integrated value S _err is equal to or less than the predetermined threshold value S _max, step S1
Return to 1.

Thus, when the reception sensitivity is poor (for example, when the user has taken the antenna or entered the underground parking lot, etc.), it is determined that the information has been sufficiently collected simply by passing the time. Therefore, the information size table of the SRAM 6 is not updated. Also, if the information can be received from time to time, information sufficient to update the information size will be available someday. Thus, in step S15, by waiting for the reception time integrated value S _{er r} is greater than a predetermined value, the data group sufficiently DRAM
5 until it is stored. Step S
If the update of the information size table of the SRAM 6 is performed when the data group is not sufficiently stored in the DRAM 5 without performing step 15, the information size of each updated mesh area may be smaller than the broadcasted information size. This is not preferable because the information size comparison switching unit 11 may automatically track the frequency of another broadcasting station.

In step S15, when the integrated reception time value S _err is equal to or greater than the predetermined threshold value S _max , the information size updating unit 8 outputs a request for updating the information size table of the SRAM 6 to the update history processing unit 9 and the information size updating unit 8 described later. the size of the stored data group to SRAM6 by SRAM update history processing updates to the latest (S16), reset again, the time count value t ₁ of the internal timer to 0 (S17), step S
Return to 11.

Here, the predetermined time T ₁ is 2.5 to
A setting of 10 minutes is preferred. If the time is shorter than 2.5 minutes, the error rate of the DARC decoder 4 cannot be detected with sufficient accuracy.
There is a tendency to update the information size table of M6.
If it is longer than minutes, the detection time of the error rate of the DARC decoder 4 is too long, and the information size table of the SRAM 6 is not easily updated.
This is because there is a tendency that tuning to the optimal FM broadcast station is not performed.

It is preferable that the threshold value S _max of the integrated reception time value S _err be set to 2.5 to 10 minutes. If less than 2.5 minutes, DARC decoder 4
Since the receiving time is too short, sufficient information is not accumulated in the DRAM 5, and the information size comparison switching unit 11 described later tends to be unable to select the optimal FM broadcast station. If the value is large, the reception time of the DARC decoder 4 is too long, so that the user waits while receiving the same information many times, and the update of the information size table in the SRAM 6 tends to be delayed.

Next, at step S16 in FIG.
The AM history update processing will be described. The SRAM history update processing is performed in the update history processing unit 9 in FIG.

FIG. 8 is a flowchart showing the processing operation of the update history processing unit, and FIG. 9 is a diagram showing the structure of the update information size table.

[0093] First, update history processing unit 9, the information size updating unit 8, the mesh code obtained by decoding the multiplexed signal transmitted from a broadcast station x at the frequency f _x M _j (j
Is a subscript corresponding to all mesh areas in the service area of the broadcasting station x. ) Data group information size S
₀ (f _x, M _j) When is input, in a memory provided therein, as shown in FIG. 9, each mesh code M _j and information size _{S 0 (f x, M j} ) and An update information size table which is a table corresponding to each is created (S20). Next, the information of the mesh code M _j of the update information size table size _{S 0 (f x, M j} ) and SRAM6 the stored frequency f _x, the mesh code M _j of information on the last day size S ₁ (f _x , M _j ) and S ₁ (f _x , M _j ) <S
₀ (f _x, M _j) is rewritten information last day stored in SRAM6 in the case of size _{S 1 (f x, M j} ) the _{S 0 (f x, M j} ) to (S21). Thereby, the update history processing unit 9
Is updated in the information size table stored in the SRAM 6.

Next, the zero clear processing unit 16
It is detected whether or not a data block has been output from the decoder 4 (S22), and if a data block has been output, the SRAM history update processing ends. Step S2
In 2, when no data block is output,
For the frequency f _x and mesh code M _y of the current mesh area belongs the vehicle position of the broadcasting station x currently tuning, "previous information size" of the information size table stored in the SRAM 6 S ₂ ( f _x, "information the size of the last day" M _y) the S ₁ (f _x, and updates to the M _y), "the last of the information size of the day" S ₁ (f _x, the M _y) is updated with 0 ,"date"
Is set as the current date (S23), and the SRAM history update process ends. As a result of the processing of steps S22 and S23, for the data of the same frequency information size that cannot be distinguished from the broadcasting station and for which the broadcasting of the broadcasting station has disappeared, the automatic tracking for that frequency is stopped.

Here, the process of creating the update information size table in step S20 is performed by a method of registering the mesh code and the information size in the order of reading from the DRAM 5 and the mesh code read from the DRAM 5 by the quick sort or bubble sort. A method of registering a mesh code and an information size while arranging them in order is used, but it is preferable to generate a hash table by a hash method using the mesh code or the like as a key in view of memory efficiency and access speed.

The following is an example of the process of creating an update information size table by the hash method.

Here, it is assumed that the number n in the column of the update information size table is 1024 and the hash address is 10 bits. Also, as the key of the hash function, the upper 8 bits (X = x ₇ x ₆ x ₅ x ₄ x
₃ x ₂ x ₁ x ₀ ) and upper 8 bits of map coordinates Y (Y = y _{7
y 6 y 5 y 4 y 3} y 2 y 1 y 0) to use (hereinafter, this (X, Y) expressed by the called a key code data group K). The hash function is performed by the equation (Equation 1).

[0098]

(Equation 1)

In equation (1), “|” represents a bit OR logic.

FIG. 10 is a flowchart showing the operation of the update history processing unit for creating the update information size table.

First, the update information size table is initialized (S30). Here, the initialization of the update information size table means that all the mesh codes registered in the update information size table are invalidated and the information size of all the mesh codes is set to 0.

Next, an internal variable i representing the number of data groups read from the DRAM 5 is set to 0 (S21), and it is determined whether or not i has reached the number of all data groups stored in the DRAM 5 (S21). S22), i is DRAM
If 5 does not reach the number of all the data groups stored, reads the i-th data group from DRAM 5, the hash function h ₀ key code K of the read data groups to the i-th and (i) as the key The hash address j = h ₀ (K (i)) is calculated (S33).
Next, it is determined whether or not the column of the j-th update information size table is empty (S34). If the column of the j-th update information size table is empty, the j-th update information size table is empty. Mesh code Ms (j) in the column of the size table
Is the mesh code M (i) of the data group read i-th, and the information size S ₀ (i) of the data group read i-th in the information size S ₁ ′ (j) of the column of the j-th update information size table. i) is added (S35), i
Is increased by 1 (S41), and the process returns to step S32.

In step S34, if the j-th update information size table field is not empty, the mesh code Ms in the j-th update information size table field
(J) is compared with the mesh code M (i) of the i-th read data group (S36).
If Ms (j) = M (i), the mesh code Ms (j) of the data group in which the mesh code Ms (j) in the column of the j-th update information size table is read i-th
(I), add the information size S ₀ (i) of the i-th read data group to the information size S ₁ ′ (j) in the column of the j-th update information size table (S35), and increase i by 1. (S41), and returns to step S32.

In step S36, Ms (j) ≠ M
In the case of (i), it is determined whether or not j is the last number n of the update information size table (S37). When j = n, j = 0 is set (S38), and when j ≠ n Is increased by 1 (S39).

Next, it is determined whether or not j is equal to h ₀ (K (i)) (S40). If j is not equal to h ₀ (K (i)), the process returns to step S34. j and h ₀ (K
If (i)) are equal, i is increased by 1 (S41),
It returns to step S32.

In step S22, i is DR
When the number of all the data groups stored in the AM 5 has been reached, it is determined that the processing for all the data groups stored in the DRAM 5 has been completed, and the processing for creating the update information size table is completed.

By the above operation, the update information size table, which is a table of the mesh codes and the sum of the information sizes corresponding to the mesh codes, is updated.
Is generated on the memory provided inside the.

Next, the process of reflecting the update information size table of the update history processing unit in the above-described step S21 in the SRAM will be described in further detail.

FIG. 11 is a flowchart showing a processing operation of the update history processing section for reflecting the update information size table in the SRAM.

In the process of reflecting the update information size table in the update history processing unit in the SRAM, the step of updating the data of each mesh code for the frequency already registered in the information size table (S50), and the step of registering the data in the information size table. The step (S51) of adding data of each mesh code to the frequency not performed.

In step S50, the current channel is selected.
Frequency f_xRegister in update data group table
Each mesh code M_yData of the update history processing
The unit 9 is an information size table stored in the SRAM 6
Check if it is registered in the
Is the information size S registered in the information size table.
₁(F_x, M_y) And registered in the update information size table
Information size S₁’(F_x, M_y) And S
₁(F_x, M_y) <S₁’(F_x, M_y), S
₁(F_x, M_y) To S₁’(F_x, M_y)
U. The specific method is the information size table and update information
Depending on the format of the size table, for example,
The report size table uses the key code K as a key.
A description will be given below of a case in which the table is configured with a hash table.

FIG. 12 is a flowchart showing a processing operation of updating the mesh data already in the information size table of the update history processing section.

First, an internal variable i representing the number of data groups read from the SRAM 6 is set to 0 (S60), and it is determined whether or not i has reached the number of all columns of the information size table stored in the SRAM 6. (S61), if i does not reach the number of all the columns of the information size table stored in the SRAM 6, the mesh code M ₁ (i) and the frequency f ₁ (i) of the i-th column from the SRAM 6 are changed. Read, i-th read mesh code M ₁ (i)
Using the key code K (i) as a key, a hash address j = h ₀ (K (i)) is calculated by the hash function h ₀ (S
62). Next, it is determined whether or not the column of the j-th update information size table is empty (the mesh code in the column of the j-th update information size table is invalid) (S63).
If the column of the j-th update information size table is empty, i is increased by 1 (S71), and the process returns to step S61.

In step S63, if data is recorded in the column of the j-th update information size table, the mesh code M ₁ '(j) in the column of the j-th update information size table is read. Mesh code M ₁
(I) a mesh code M ₁ '(j) are equal and the frequency f ₁ (i) and the frequency f _x currently selected channel determines whether equal (S64).

If the condition is satisfied in step S64, the "information size of last day" S in the i-th column of the information size table stored in the SRAM 6
_It is determined whether ₁ (i) is smaller than the information size S ₁ ′ (j) in the column of the j-th update information size table (S
65), if S ₁ (i) <S ₁ ′ (j), the “information size of the last day” S ₁ (i) in the i-th column of the information size table stored in the SRAM 6 is updated to the j-th. The information size is updated to the information size S ₁ ′ (j) in the column of the information size table, the “date” in the ith column of the information size table is updated to the current date, and the mesh code M ₁ ′ (j) is invalidated. And the information size S ₁ ′ (j) is set to 0 (S66).

In step S64, if the condition is not satisfied, it is determined whether or not j is the last number n of the update information size table (S67). If j = n, j = 0 is set. (S68), j is 1 when j ≠ n
Increase (S69).

Next, it is determined whether or not j is equal to h ₀ (K (i)) (S70). If j is not equal to h ₀ (K (i)), the process returns to step S63. j and h ₀ (K
If (i)) are equal, i is increased by 1 (S71),
It returns to step S61.

In step S61, i is equal to SR
If the number of all the columns of the information size table stored in the AM 6 has been reached, it is determined that the processing for all the columns of the information size table stored in the SRAM 6 has been completed, and the information size table already exists. The process of updating the mesh data ends.

With the above operation, the update information size table of the update history processing section 9 is reflected on the data already registered in the information size table of the SRAM 6.

Step S51 is a process of adding, to the information size table, frequency and mesh code data not registered in the information size table of the SRAM 6 in the update information size table. There is no problem if the memory size of the SRAM 6 is sufficiently large.
In the case where the memory size of No. 6 is limited, when adding the data of the frequency and the mesh code to the information size table, it is necessary to perform a process of deleting unnecessary data at the same time. In this case, the data of the mesh area far from the mesh area to which the current vehicle position belongs may be deleted. Hereinafter, an example of a process of adding mesh data not in the SRAM will be described below.

FIG. 13 is a flowchart showing the processing operation of the update history processing section for adding mesh data not stored in the SRAM.

First, the update history processing unit 9 sets an internal variable j representing the number of checked columns in the update information size table to 0 (S80), and j is the update history stored in the update history processing unit 9. It is determined whether or not the number of all the columns of the use information size table has been reached (S81), and j is the update history processing unit 9
If the number of all the columns of the update information size table stored in the update information size table has not been reached, the mesh code M ₁ ′ (j) and the frequency f ₁ ′ (j) of the j-th column are updated from the update information size table. Reading is performed (S82). Next, the column of the j-th update information size table is empty (the mesh code of the j-th update information size table is invalid).
It is determined whether or not it is (S83). If the column of the j-th update information size table is empty, j is incremented by 1 (S83).
87), returning to step S81.

In step S83, if data is recorded in the column of the j-th update information size table, the mesh code M ₁ '(j) in the column of the j-th update information size table is read. Next, the update history processing unit 9 checks whether there is a free area in the memory area of the SRAM 6 (S84). If there is no free area in the memory area of the SRAM 6, the update history processing unit 9 stores the information in the information size table of the SRAM 6. Among the data, a process of deleting data of a mesh area far from the mesh area to which the current vehicle position belongs is performed (S85). This processing will be described later. Next, the data is added to the empty area of the memory of the update history processing unit 9 in the column of the j-th update information size table (S8).
6) Increment j by 1 (S87), and return to step S81.

If j has reached the number of all the columns of the update information size table in step S81, the processing for all the columns of the update information size table stored in the update history processing unit 9 is performed. Is completed, and the process of adding mesh data not present in the SRAM ends.

Next, the SRA in step S85 is performed.
The processing for deleting the mesh area information of M is described.

As a specific method, when there is no free space in the memory area of the SRAM 6, the data of the mesh area furthest from the mesh area to which the current vehicle position belongs is deleted from the information size table stored in the SRAM 6. Or a method of erasing a certain percentage of data from the information size table stored in the SRAM 6 in the order of the mesh area farthest from the mesh area to which the current vehicle position belongs, but the latter method is used. Is preferred because the overall processing time can be reduced. In the following, as an example, when there is no free space in the memory area of the SRAM 6, 10% of the data is stored in the information size table stored in the SRAM 6 in the order of the mesh area furthest from the mesh area to which the current vehicle position belongs. A method for erasing will be described.

FIG. 14 is a flowchart showing the processing operation of the update history processing section for deleting the far mesh area information in the SRAM.

Here, the update history processing section 9 stores a variable D representing a distance to a mesh area closest to the mesh area to which the current vehicle position belongs in a memory area provided therein.
n, a variable Df representing the distance from the mesh area to which the current vehicle position belongs to the furthest mesh area, a variable D representing the distance from the mesh area to which the current vehicle position belongs to each mesh area, the current vehicle position A section counter table C (0) to an area counter table C (0), which is an array obtained by dividing the distance from the mesh area closest to the mesh area to which the vehicle belongs to the distance from the mesh area to which the current vehicle position belongs to the farthest mesh area into 300 sections. C (29
9), a variable j indicating the number of data read from the SRAM 6 is stored.

First, the update history processing unit 9 obtains the current vehicle position from the vehicle position detection unit 19, checks the mesh code of the information size table stored in the SRAM 6,
The distance Dn to the mesh area closest to the mesh area to which the current vehicle position belongs and the distance Df to the mesh area farthest from the mesh area to which the current vehicle position belongs are acquired (S91). Actually, since the mesh code is represented by the code of the reference area mesh of JIS X0410, the distance to each mesh area can be acquired by the mesh code.

Next, the update history processing unit 9 initializes a variable D representing the distance from the mesh area to which the current vehicle position belongs to each mesh area to 0 (S92), and stores the section counter tables C (1) to C (1). C (300) is initialized to 0 (S93). Next, a variable j representing the number of data read from the SRAM 6 is initialized to 0 (S94). Next, it is determined whether or not j has reached the total number N of columns of the information size table stored in the SRAM (S95), and j is determined to be S.
If the total number N of columns of the information size table stored in the RAM has not been reached, the mesh code M ₁ (j) of the j-th column of the information size table is obtained, and the mesh code M
_{If 1} (j) is an invalid value (S96), j is incremented by 1 (S100), and the process returns to step S95. In step S96, if the mesh code M ₁ (j) is a valid value, the distance between the mesh code M _y and the mesh code M ₁ (j) of the mesh area to which the current vehicle position belongs is determined. Is obtained and stored in the variable D. Next, it is checked whether or not the variable D is between the distance Dn and the distance Df (S98). If the variable D is between the distance Dn and the distance Df, j = [(D−Dn) × ( 300-1) / (Df-
Dn)] and calculate the counter C in the section counter table.
(J) is incremented by 1 (S100), and the process returns to step S95. If the variable D is not between the distance Dn and the distance Df in step S98, the counter C (j) in the section counter table is increased by 1 (S100), and step S95 is performed.
Return to

In step S95, if j has reached the total number N of columns of the information size table stored in the SRAM, the counter C (j) is added from C (299) in descending order of the index, and the total sum Nk = C (29
9) + C (298) +... + C (k) is (N + 1) ×
When the index exceeds 0.1 (10% of the total number of data), the index is k (S101), and Nk is (N + 1) × 0.
2 (20% of the total number of data) is determined (S102). If Nk does not exceed (N + 1) × 0.2, it is determined from the mesh area to which the current vehicle position belongs. The data of the information size table of the mesh area located farther than the distance D (k) corresponding to the index k is deleted from the memory area of the SRAM 6 (S103).
The process of deleting the distant mesh area information of the SRAM ends.

In step S102, Nk becomes (N +
1) If it exceeds 0.2, the data of the information size table of the mesh area that is farther than the distance D (k + 1) corresponding to the index k + 1 from the mesh area to which the current vehicle position belongs is stored in the SRAM 6. The data is erased from the memory area (S104), Dn is set to D (k), Df is set to D (k + 1), and the process returns to step S93.

By the above operation, of the update information size table, the data of the frequency and mesh code which are not registered in the information size table of the SRAM 6 are additionally registered in the information size table, and the update history processing section 9
If there is no empty area in the memory of the vehicle, the data in the mesh area far from the mesh area to which the current vehicle position belongs is deleted.

Next, a description will be given of a process of requesting the switching of the detection frequency based on the error rate comparison. The detection frequency switching request processing based on the error rate comparison is performed in the error rate comparison switching unit 12 in FIG. In this processing operation, the error rate comparison switching unit 12
If the time outputted by the error rate P _err of C decoder 4 is equal to or greater than a predetermined threshold value ε continues for a predetermined period of time T ₂ or more, out of the service area of the broadcasting station frequency f _x of the own vehicle is currently selected channel And the PLL frequency demodulator 3
Outputting a request for switching the detection frequency in the frequency f _x 'of the broadcasting stations neighboring to the broadcasting station of the frequency f _x to set.

FIG. 15 is a flowchart showing the operation of requesting switching of the detection frequency based on the error rate comparison of the error rate comparison switching unit.

First, the error rate comparison switching unit 12 resets a time value t ₂ of a timer provided therein to 0 (S110), and starts time measurement (S111).

Next, the error rate comparison switching unit 12
The error rate P _err is obtained from the ARC decoder 4 (S
112), it is determined whether the error rate P _err is less than a predetermined threshold value (S113), in the case of P _err <epsilon is
It returns to step S110. In step S113,
If P _err ≧ ε, it is determined whether the timer value t ₂ has reached a predetermined time T ₂ (for example, 6 minutes) (S11).
4) If t ₂ <T ₂ , the process returns to step S112 and t
_{If 2} ≧ T _2, the frequency f _x currently being tuned by the vehicle
It is determined that the user is outside the service area of the broadcasting station, and a request S1 for switching the detection frequency to the frequency f _x ′ of the adjacent broadcasting station is made.
Is output to the switching determination unit 13 (S115).

[0138] Here, the frequency of the adjacent broadcasting station is transmitted as supplementary data shorter than the broadcasting station as management information of the broadcasting station called additional information or data for D-GPS. This additional information includes an alternative frequency table, which is a list of frequency information that may be switched by the receiver when the receiving broadcast station cannot receive the broadcast station. Information about the frequency of the station can be obtained. The error rate comparison switching unit 12 receives each of these frequencies for 10 seconds and selects the frequency with the lowest error rate.

Next, a process of requesting to switch the detection frequency based on the information size comparison will be described. The process of requesting to switch the detection frequency based on the information size comparison is performed in the information size comparison switching unit 11 in FIG. In this processing operation, the information size comparison switching unit 11 compares the information sizes stored in the SRAMs for all the broadcasting stations whose service area is the mesh area to which the current vehicle position belongs, and determines the largest information size. It outputs a request to switch to a larger broadcast station frequency.

FIG. 16 is a flow chart showing a detection frequency switching request processing operation based on the information size comparison of the information size comparison switching unit.

First, the information size comparison switching unit 11 has an internal
Value t of the timer provided for_ThreeIs reset to 0 (S
120), start timing (S121), and count timer
Value t _ThreeIs a predetermined time T_Three(E.g. 5 minutes)
(S122). This is because some data is stored in DRAM5.
Data size is stored in the information size update unit 8 and the update
The size of the information stored in the SRAM 6 by the history processing unit 9
The frequency f at which the cable is currently tuned_xUpdated regarding
In order to wait.

[0142] When the time count value t ₃ of the timer reaches a predetermined time T _3, the information size comparison switching unit 11, the information of all the frequency corresponding to the mesh code M _y mesh area belongs the current position of the vehicle size To the information size reading processor 1
0 is obtained from the information size table stored in the SRAM 6 (S123). At this time, information size reading processing unit 10 is subjected from the information size table for SRAM 6, the frequency f _j (j mesh code M _y is in correspondence with each broadcast station including a mesh code M _y within the service area “Information size of last day” S ₁ (f _j , M
_y) and "previous information size" _{S 2 (f j, M y} ) and reads and outputs whichever is greater of the information size S ₃ (f _j, the information size comparison switching section 11 as M _y). This is because the information size of the last day S ₁ (if the FM radio wave cannot be received temporarily because the vehicle is located behind a tunnel or a building when the update history processing unit 9 is updated, S ₁ ( f _j ,
Although M _y) is updated to 0, by such temporary poor reception, a process of information size S ₃ (f _j, 0 as M _y) is carried out in order to prevent the output.

Next, the obtained information sizes are compared, and the frequency f corresponding to the largest information size is obtained.
_x ′ is obtained (S124). Then, 'compares the frequency f _x of the broadcast station and the currently selected channel (S125), the frequency f _x and the frequency f _x' acquired frequency f _x when a and different, the PLL frequency demodulator 3 Set frequency to frequency f
_The switching signal S2 for switching to _x ′ is output to the switching determination unit 13 (S126).

When the above operation is completed, step S is executed again.
The operation returns to operation 123.

Next, the detection frequency switching process will be described. The detection frequency switching process is performed by the switching determination unit 13 in FIG.

FIG. 17 is a flowchart showing detection frequency switching processing.

First, upon receiving a request S1 or S2 for switching the detection frequency to the frequency f _x ′ of an adjacent broadcasting station, the switching judgment unit 13 changes the frequency f _x from the frequency f _x currently set in the PLL frequency demodulator 3 to the frequency f _{x. x} 'is set (S130).
Next, it is checked whether or not there is an output from the detection tuner 2 (S131).

Here, whether or not there is an output from the detection channel selector 2 depends on the hardware specifications of the PLL frequency demodulator 3, but for example, lock detection of the PLL frequency demodulator 3, SD signal detection from demodulator 3,
This is performed by determining the IF frequency of the PLL frequency demodulator 3 or the like.

If the output from the detection channel selection unit 2 is detected in step S131, the switching judgment unit 13
It is checked whether or not there is a packet output from the decoder 4 (S132).

Here, whether or not there is a packet output from the DARC decoder 4 depends on the hardware specifications of the DARC decoder 4. For example, it is necessary to check that the output data packets are synchronized. This is performed by confirming that the output data packet is normal data (not parity data).

When the data packet is output from the DARC decoder 4 in step S132, the switching judgment unit 13 sends the data group constructing unit 7, the information size updating unit 8, the information size comparison switching unit 11, and the error rate comparison switching unit 12 to each other. A reset signal is output (S133). When a reset signal is input, the data group constructing unit 7, the information size updating unit 8, the information size comparing and switching unit 11, and the error rate comparing and switching unit 12 stop their operations up to that point and reset them. Resume processing.

In step S131, when the output from the detection channel selector 2 is not detected, or in step S13.
If the data packet from the DARC decoder 4 in 2 is not output (i.e., if a new automatic tracking fails), the frequency f _x 'and mesh code M _y of the current mesh area belongs vehicle position newly tuned respect, SRAM 6 to "previous information size" of the information size table stored _{S 2 (f x ', M} y) "information size of the last day" of _{S 1 (f x', M} y) in updated, "information the size of the last day" _{S 1 (f x ', M} y) was updated with 0, and the current date the "date" (S134). Then, return the set frequency of the PLL frequency demodulator 3 f _x (S135), and terminates the switching process of the detection frequency.

In addition, in addition to the above processing, when the date of the date and time output by the clock 14 is changed, the information size table updating unit 15 changes the “previous information size” of all the columns of the information size table of the SRAM 6 to “ Update processing to "information size of last day". Thereby, the information on the old data information size is updated at least every day.

As described above, according to the present embodiment, (1) DARC decoder 4 and data group construction unit 7
The data group of the VICS information generated from the multiplexed signal is sequentially stored in the DRAM 5.

(2) The information size updating unit 8 outputs a request for updating the information size table to the update history processing unit 9 when the data group is stored in the DRAM 5 for a predetermined time or more, and Update the information size of each mesh code transmitted from the broadcasting station. At this time,
If the information size to be updated is smaller than the information size already registered in the information size table, it is not updated. When the information size to be updated is 0, the information size of the mesh code to which the current frequency and the current vehicle position in the information size table belong is updated to 0.

(3) On the other hand, the error rate comparison switching section 12
Is the error rate P output from the DARC decoder 4.
_{If err} time larger than a prescribed threshold value ε continues for a predetermined period of time T ₂ or more, the current detection frequency, detection frequency of the other broadcasting station which broadcast area and broadcast area of the broadcast station of the currently selected station adjacent Is output as the switching request S1.

[0157] (4) At the same time, information size comparison switching unit 11 waits for the update information size table SRAM6 is performed for a predetermined time T _3, the current which is registered in the information size table The information size of each frequency of the mesh code to which the own vehicle position belongs is compared, and a switching request S2 for switching the detection frequency to the frequency of the information size of the largest size (the largest amount of information) is output.

[0158] (5) switching determination unit 13, when the switching request S1 or S2 is input, the current detection frequency f _x set in the PLL frequency demodulator 3 has been detected frequency f _x 'of change request Switch. Thereafter, if there is an output from the detection channel selector 2 and a data packet output from the DARC decoder 4, the data group constructing unit 7, the information size updating unit 8, the information size comparison switching unit 11, the error rate comparison switching A reset signal is output to the section 12 to reset and restart the operation of each section. When there is no output from the detection channel selection unit 2 or when there is no data packet output from the DARC decoder 4, the frequency f _x ′ in the information size table and the information size of the mesh code to which the current position of the vehicle belongs belong. 0, updated to PL
Set frequency of the L frequency demodulator 3 is returned to the f _x. A series of operations automatically broadcast the broadcast station having the largest amount of information around the current vehicle position among the broadcast stations broadcasting the receivable VICS information at the current vehicle position.
ICS information can be obtained.

[0159]

As described above, according to the receiving device of the car navigation system of the present invention, the following advantageous effects can be obtained.

According to the first aspect of the present invention, the detection frequency is switched to the broadcasting station having the largest amount of information at the own vehicle position by the information size comparing and switching means, so that the information broadcasting station that can always receive at the own vehicle position. Of these, the information broadcasting station that provides the largest amount of road traffic information near the vehicle position can be automatically selected, so the road traffic information provided by the information broadcasting station can be used effectively. It is possible to provide a receiving device of a car navigation device that can perform the operation.

According to the second aspect of the present invention, (1) when the frequency cannot be received in the mesh area where the own vehicle is located, for example, when the broadcast station stops broadcasting, another broadcast is automatically transmitted. Since a station can be selected, it is possible to provide a receiving device of a car navigation device capable of effectively utilizing road traffic information provided by an information broadcasting station.

(2) When the error rate comparison switching means determines that the own vehicle has gone out of the service area of the information broadcasting station,
It is possible to set a longer determination time for the error rate to be equal to or higher than a predetermined threshold, and to set a longer time.If the vehicle travels in a place with poor reception of radio waves such as a tunnel or behind a shield while traveling, It is possible to provide a receiving device of a car navigation device that can prevent the frequency of the information broadcasting station from being erroneously switched and can effectively use the road traffic information provided by the information broadcasting station.

According to the third aspect of the present invention, when the information broadcasting station selected after the switching has stopped broadcasting, the selection of the broadcasting station is prevented, and the information broadcasting station is provided with the information broadcasting station. Receiving device of a car navigation device that can effectively utilize road traffic information.

According to the fourth aspect of the present invention, it is possible to prevent the information size of information received in a poor reception state due to the presence of a shield such as a building from being registered or updated in the information size storage means. By registering or updating a small information size, it is possible to prevent the information size comparison / switching means from erroneously switching the frequency and to use the road traffic information provided by the information broadcasting station effectively. And a receiving device for a car navigation device.

According to the fifth aspect of the invention, when the information broadcasting station temporarily stops broadcasting and 0 is registered in the information size of the last day corresponding to the frequency and the mesh code in the information size table. Also, even if a small value is registered in the information size of the last day corresponding to the frequency and the mesh code due to accidentally traveling in an area where the reception condition is bad, the information size comparison switching means is not the same as the previous information size. Since the information size is compared with the information size of the last day, the larger one is read out as the information size and compared, and the detection frequency of the receiving means is switched, the accuracy of selecting an information broadcasting station is improved, and the information broadcasting station is improved. It is possible to provide a receiving device of a car navigation device capable of effectively utilizing the provided road traffic information.

According to the invention described in claim 6, when the information broadcasting station stops broadcasting, the information in the information size table is set to zero so that the data size of the broadcasting station remains in the information size table forever. Is prevented, the information size comparison switching means can prevent the information broadcast station from erroneously continuing to select the broadcast station even if the broadcast station has stopped broadcasting, and the information broadcast station is provided with the information broadcast station. It is possible to provide a receiving device of a car navigation device capable of effectively utilizing road traffic information.

Further, according to the frequency switching method of the receiving device of the car navigation device of the present invention, the following advantageous effects can be obtained.

According to the seventh aspect of the present invention, since the detection frequency is switched to the broadcast station having the largest amount of information at the position of the own vehicle, among the information broadcast stations that can be received at the position of the own vehicle, the detection frequency is always changed An information broadcasting station providing the largest amount of road traffic information near a position can be automatically selected, and the road traffic information provided by the information broadcasting station can be used effectively. A frequency switching method for a receiving device of a car navigation device can be provided.

According to the eighth aspect of the present invention, (1) when the frequency cannot be received in the mesh area where the own vehicle is located, for example, when the broadcasting station stops broadcasting, another broadcasting is automatically performed. You can select a station,
It is possible to provide a frequency switching method of a receiving device of a car navigation device, which can effectively use road traffic information provided by an information broadcasting station.

(2) When it is determined that the own vehicle has gone out of the service area of the information broadcasting station, the determination time for which the error rate continues to be equal to or higher than the predetermined threshold can be set longer, and the own vehicle can be set longer. Is provided by the information broadcasting station because it is possible to prevent the frequency of the information broadcasting station from being erroneously switched when traveling in a place where the reception condition of radio waves is poor, such as a tunnel or a shadow of a shield while traveling. It is possible to provide a frequency switching method of a receiving device of a car navigation device that enables effective use of road traffic information.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a device configuration of a receiving device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a data format of a data frame.

FIG. 3 is a diagram showing a data format of the data packet of FIG. 2;

FIG. 4 is a diagram showing a data format of a data group.

FIG. 5 is a diagram showing a data structure stored in an SRAM.

FIG. 6 is a flowchart showing the operation of a data group construction unit.

FIG. 7 is a flowchart illustrating a processing operation of an information size updating unit;

FIG. 8 is a flowchart illustrating a processing operation of an update history processing unit.

FIG. 9 is a diagram illustrating a configuration of an update information size table.

FIG. 10 is a flowchart illustrating an update information size table creation processing operation of the update history processing unit;

FIG. 11 is a flowchart showing a processing operation of the update history processing unit for reflecting the update information size table in the SRAM.

FIG. 12 is a flowchart illustrating a processing operation of updating the mesh data already in the information size table of the update history processing unit.

FIG. 13 is a flowchart illustrating a processing operation of the update history processing unit for adding mesh data not in the SRAM.

FIG. 14 is a flowchart showing a processing operation of the update history processing unit for deleting distant mesh area information in the SRAM.

FIG. 15 is a flowchart showing a detection frequency switching request processing operation based on an error rate comparison by an error rate comparison switching unit;

FIG. 16 is a flowchart showing a detection frequency switching request processing operation based on information size comparison of the information size comparison switching unit;

FIG. 17 is a flowchart showing detection frequency switching processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiving antenna 2 Detection / selection part 3 PLL frequency demodulator 4 DARC decoder 5 DRAM 6 SRAM 7 Data group construction part 8 Information size updating part 9 Update history processing part 10 Information size reading processing part 11 Information size comparison switching part 12 Error rate comparison Switching unit 13 Switching judgment unit 14 Clock 15 Information size table updating unit 16 Zero clear processing unit 17 GPS antenna 18 GPS receiver 19 Own vehicle position detection unit 20 Map information storage unit

Continued on the front page F-term (reference) 2F029 AA02 AB07 AC02 AC06 5H180 AA01 BB02 BB04 BB13 EE18 FF05 FF12 FF13 FF27 5J103 AA13 CB00 FA03 GA11 GB04 JA08 JA13 JA19 5K067 AA34 BB36 EE02 FF03 KK15JJ01KK01 JJ01 KK15 KK10

Claims (8)

[Claims] 1. A receiving device of a car navigation device for receiving information from each information broadcasting station of a road traffic information system, wherein the receiving means receives the information of each mesh area provided by radio waves from the information broadcasting station. Own vehicle position detecting means for detecting the own vehicle position, information storage means for storing the information of each mesh area, and information for storing an information size which is the size of the information for each mesh area and each reception frequency. Size storage means, information storage means for storing and accumulating the information of each mesh area provided by the information broadcast station received by the reception means in the information storage means, and each mesh stored in the information storage means An information size registration unit that acquires the information size of the information for each area and registers or updates the information size in the information size storage unit; The information size of each reception frequency read from the information size storage means of the mesh area to which the vehicle position belongs detected by the position detection means is compared, and the detection frequency of the reception means is set to the reception frequency having the largest information size. Information size comparison switching means for switching to
A receiving device for a car navigation device, comprising: 2. A detection frequency of the receiving means is selected at that time when a state in which an error rate at the time of receiving the information of the receiving means has exceeded a predetermined threshold has continued for a predetermined time or more. 2. The receiving device for a car navigation device according to claim 1, further comprising an error rate comparison switching unit that switches to a frequency of an information broadcasting station other than the information broadcasting station. 3. The method according to claim 2, wherein the error rate comparison switching means or the information size comparison switching means switches the detection frequency of the receiving means and the receiving means does not receive the information. 3. The receiving device for a car navigation device according to claim 2, further comprising a switching determination unit for returning the frequency to the predetermined frequency. 4. The information size registering means, wherein after the information storage means starts storing the information in the information storage means, an error rate when the receiving means receives the information is equal to or less than a predetermined threshold. When the reception time of the information in the state reaches a predetermined time, acquiring the information size of the information for each mesh area stored in the information storage means and registering or updating the information size in the information size storage means. The receiving device for a car navigation device according to claim 1, wherein the receiving device comprises: 5. An information size table in which a plurality of units of data stored in said information size storage means, each unit including a reception frequency, a mesh code of a mesh area, a previous information size, and an information size of the last day, are registered. And information size table updating means for updating the previous information size of each of the information size tables to the information size of the last day when a predetermined time has elapsed, wherein the information size registration means comprises: If the information size of the last day corresponding to the information size is registered in the information size table before registering or updating the size in the information size table, the information size is larger than the information size of the last day. Is larger, the information size of the last day is updated to the information size, and the information size is updated in the information size table. If the information size of the last day corresponding to the information size is not registered in the information size table before registration, the information size is newly registered in the information size table as the information size of the last day. The information size comparison switching means compares the previous information size with the information size of the last day when reading the information size from the information size storage means, and reads the larger one as the information size. The receiving device for a car navigation device according to any one of claims 1 to 4, wherein 6. The reception after switching of the information size table when the reception means has not received the information after the error rate comparison switching means or the information size comparison switching means switches the detection frequency of the reception means. The information size of the last day is updated to the information size of the last day, and the information size of the last day is updated to 0 in a unit corresponding to a frequency and a mesh area to which the own vehicle position belongs at that time, and / or If the receiving means does not receive the information when the update history processing unit registers the information size in the information size table, the current reception frequency of the information size table and the position of the own vehicle at that time belong In the unit corresponding to the mesh area, the previous information size is updated to the information size of the last day, and the Receiving device of the car navigation device according to claim 5, the information size day characterized by comprising a zero clear processing means for updating the zero. 7. A receiving means for receiving the information of each mesh area provided by radio waves from each information broadcasting station of the road traffic information system, an own vehicle position detecting means for detecting an own vehicle position, An information storage means for storing the information, and an information size storage means for storing an information size that is the size of the information for each mesh area and each reception frequency, comprising: An information storage procedure for receiving the information of each mesh area provided from an information broadcasting station by the receiving means, storing the information in the information storage means, and storing the information; and for each mesh area stored in the information storage means. An information size registration procedure for acquiring the information size of the information and registering or updating the information size in the information size storage means,
The vehicle position is detected by the vehicle position detection means, the information size of each reception frequency of the mesh area to which the vehicle position belongs is read out from the information size storage means, the information size of each reception frequency is compared, and the reception is performed. And an information size comparison switching step of switching a detection frequency of the means to a frequency having the largest information size. 8. A state in which the error rate at the time of receiving the information of the receiving means is equal to or higher than a predetermined threshold value, which is performed in parallel with the information storage procedure, the information size registration procedure, and the information size comparison switching procedure. Error rate comparison switching procedure for switching the detection frequency of the receiving means to the frequency of an information broadcasting station other than the information broadcasting station currently selected when the predetermined time has continued for a predetermined time or more. The frequency switching method for a receiving device of a car navigation device according to claim 7.