JP2014017668A - Broadcast receiver and reception difficult area determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that it is difficult to suppress the cost because a device dedicated to determine whether or not the current position is in a reception difficult area is required.SOLUTION: The broadcast receiver includes entry determination means for determining whether or not it has entered a reception difficult area of bad reception environment on the basis of the number of receivable frequency channels, reception intensity storage means for storing the reception intensity of a frequency channel under reception, when a determination is made that it has entered a reception difficult area, comparison means for comparing the reception intensity stored by the reception intensity storage means with the reception intensity of a frequency channel under reception, and escape determination means for determining whether or not it has escaped from a reception difficult area on the basis of the comparison results by the comparison means.

Description

  The present invention relates to a broadcast receiver capable of determining a difficult-to-receive area where broadcast radio waves are difficult to reach, and a difficult-to-receive area determination method.

  A general broadcast receiver is equipped with a channel search function for searching for receivable frequency channels. This type of broadcast receiver is mounted on a moving body such as a vehicle. When it detects that a receiving frequency channel cannot be received, a channel search is started and broadcast waves that can be received at this time are detected. Search to create a list of broadcast stations that list receivable frequency channels.

  However, if a channel search is executed at the timing when a mobile object enters a place where broadcast radio waves are difficult to reach (hereinafter referred to as “receivable reception area”) such as an underground parking lot, indoors, or under an overpass, it can be received originally. The problem arises that frequency channels are not listed in the broadcast station list. In order to avoid this problem, for example, in Patent Document 1, it is determined whether or not the current position of the broadcast receiver is within the difficult reception area, and execution of the channel search is suspended while the broadcast receiver is located within the difficult reception area. A broadcast receiver is described. Specifically, the broadcast receiver described in Patent Document 1 determines that the broadcast receiver is located in an area where reception is difficult during a period in which radio waves from GPS satellites cannot be received.

JP 2008-17392 A

  However, the configuration described in Patent Document 1 requires a module that can receive radio waves from GPS satellites as a means for determining whether or not the current position is within the difficult reception area. Up. Therefore, it is desired to provide a broadcast receiver that can determine whether or not the current position is within the difficult reception area without providing the module.

  The broadcast receiver according to one aspect of the present invention is configured to determine whether or not an entry determination unit determines whether or not an entry is made in an area where reception is difficult based on the number of receivable frequency channels, and an entry in an area where reception is difficult. Reception power storage means for storing the reception strength of the frequency channel being received when judged, and comparison means for comparing the reception strength stored by the reception strength storage means with the reception strength of the currently received frequency channel; And an escape determining means for determining whether or not the vehicle has escaped from the difficult reception area based on a comparison result by the comparing means.

  According to one aspect of the present invention, it is not necessary to provide a dedicated device for determining whether or not the current position is in an area where reception is difficult, which is advantageous for cost reduction.

  Further, the escape determination means may determine that it has escaped from the difficult reception area when the reception intensity of the currently received frequency channel is higher than the reception intensity stored in the reception intensity storage means by a predetermined value or more.

  The broadcast receiver may include a storage unit that stores the channel list and an update unit that updates the channel list stored in the storage unit based on the reception state of the frequency channel. For example, the updating unit stops updating the channel list for a period of time within the difficult reception area.

  The broadcast receiver is connected to the ACC power source of the mobile body, and detects the on / off of the ACC power source, and displays the channel list on a predetermined display screen based on the detection result of the detection unit. It is good also as a structure provided with the display control means to control.

  Further, the display control means, when the ON / OFF of the ACC power source is detected by the detection means during the period located in the difficult reception area, when the escape determination means determines that it has escaped from the difficult reception area, The same channel list as when entering the difficult reception area may be displayed on the display screen.

  Further, the display control means is a case where the on / off of the ACC power source is not detected by the detection means during the period located in the difficult reception area, and the escape determination means determines that it has escaped from the difficult reception area The channel list updated by the updating means after the exit may be displayed on the display screen.

  In addition, the update means is a case where the detection means does not detect ON / OFF of the ACC power supply during a period located in the difficult reception area, and when the escape determination means determines that it has escaped from the difficult reception area, The interval for checking the reception state of each frequency channel may be shortened as compared to the time other than when the user has not escaped from the difficult reception area.

  In addition, the reception difficulty area determination method according to an aspect of the present invention includes an entry determination step for determining whether or not an entry has occurred in a reception difficulty area having a poor reception environment based on the number of receivable frequency channels, and a reception difficulty area. The reception strength storage step for storing the reception strength of the frequency channel being received, the reception strength stored in the reception strength storage step, and the reception strength of the frequency channel currently being received. A comparison step for comparison and an escape determination step for determining whether or not the vehicle has escaped from the difficult reception area based on a comparison result in the comparison step.

  According to the broadcast receiver and the difficult reception area determination method according to one aspect of the present invention, it is not necessary to provide a dedicated device for determining whether or not the current position is within the difficult reception area, which is advantageous for cost reduction. is there.

It is a block diagram which shows the structure of the broadcast receiver of embodiment of this invention. It is a figure which shows the structure of the receivable station database of embodiment of this invention. It is a figure which shows the example of a broadcast station list displayed on the display screen of the display of the broadcast receiver of embodiment of this invention. It is a figure which shows the flowchart of the reception difficulty area approach determination process performed in embodiment of this invention. It is a figure which shows the flowchart of the reduction determination process of the receivable broadcasting station of S2 of FIG. It is a figure which shows the update example of a receivable station database. It is a figure which shows the flowchart of the difficult reception area escape determination process performed in embodiment of this invention.

  Hereinafter, a broadcast receiver according to an embodiment of the present invention will be described with reference to the drawings. The broadcast receiver of the present embodiment is a radio receiver suitable for reception of RDS (Radio Data System) multiplex broadcasts, but radio receivers and television receivers suitable for reception of other multiplex broadcast systems are also present. It is a category of the invention.

  FIG. 1 is a block diagram showing a configuration of a broadcast receiver 1 according to an embodiment of the present invention. The broadcast receiver 1 is a vehicle-mounted broadcast receiver (for example, one that constitutes an audio with a display or a vehicle-mounted navigation device) and is installed in a vehicle such as a general passenger car. The vehicle-mounted navigation device includes a PND (Portable Navigation Device). The broadcast receiver 1 is designed to be compatible with multiplex broadcasting by the RDS method, and is configured to receive and process a broadcast signal in the signal format of the broadcast method. In addition, the broadcast receiver 1 is good also as what comprises a portable information terminal, such as a smart phone, a feature phone, and a portable game machine.

  As shown in FIG. 1, a broadcast receiver 1 includes an antenna 101, a tuner 102, a radio signal processing circuit 103, an audio signal processing circuit 104, a power amplifier 105, a speaker 106, an RDS demodulator 107, and a PLL (Phase Locked Loop). A circuit 108, a microcomputer 109, an input interface 110, and a display 111 are provided. The microcomputer 109 is mounted with a plurality of built-in RAMs corresponding to each application. The plurality of built-in RAMs may be a single built-in RAM.

  The broadcast receiver 1 receives broadcast radio waves with the antenna 101 and outputs them to the tuner 102. The tuner 102 extracts an RF (Radio Frequency) signal of the selected station from the received radio wave under the control of the microcomputer 109 via the PLL circuit 108. The extracted RF signal is frequency-converted to an intermediate frequency suitable for signal processing such as filtering. The tuner 102 outputs an IF (Intermediate Frequency) signal obtained by frequency conversion to the radio signal processing circuit 103.

  The selected station is designated by a user operation on the input interface 110, for example. The designation information of the selected station is stored in a built-in RAM (Random Access Memory) of the microcomputer 109. For example, immediately after the broadcast receiver 1 is turned on, the microcomputer 109 controls the channel selection operation of the tuner 102 via the PLL circuit 108 according to the information stored in the built-in RAM. Note that the input interface 110 is assumed to be hardware, software, or various UIs (User Interfaces) combining these, and specifically, mechanical switch keys and membranes mounted on the front panel of the broadcast receiver 1 main body. Examples thereof include a key, a GUI (Graphical User Interface) provided in a touch panel environment, a remote controller on which operation keys are mounted.

  The radio signal processing circuit 103 has an IF detection (IF-Detection) circuit, a noise canceller (Noise Canceller), and a weak electric field processing (Multiplex) circuit. The IF signal input to the radio signal processing circuit 103 is detected as an audio signal by the IF detection circuit, and then noise is removed by a noise canceller. The audio signal is processed by the weak electric field processing circuit according to the reception state of the selected station such as mute, high cut, and separation control, and is output to the audio signal processing circuit 104.

  The audio signal input to the audio signal processing circuit 104 is output and reproduced as sound from the speaker 106 after predetermined audio signal processing and after gain adjustment according to the volume by the power amplifier 105.

  The radio signal processing circuit 103 includes, for example, an S meter. The S meter measures the value of the detection voltage at the time of demodulating the analog audio signal at a predetermined sampling period and outputs it to the microcomputer 109. The detected voltage value is a DC voltage proportional to the received radio wave (the electric field strength of the received broadcast radio wave).

  The signal detected by the radio signal processing circuit 103 is also output to the RDS demodulator 107. The detection signal is demodulated by the RDS demodulator 107, decoded by the RDS decoder of the microcomputer 109 into RDS data (multiplexed data of the RDS method), and stored in the data RAM 112 of the microcomputer 109. RDS data is data representing channel information of frequency channels, and includes PS (Programme Service), RT (Radio Text), AF (Alternative Frequencies) list, PI (Programme Identification) code, PTY (Programme Type), TP (Traffic Programme). ) Etc. are included.

  For example, consider a case where a normal channel search process is executed in accordance with a user operation on the input interface 110. When the channel search process is executed, the PI code of the receivable frequency channel is registered in the receivable station database in the DB RAM 113 of the microcomputer 109, and the RC (Receivable Counter) and DBC (Data Base Counter) are registered. Is set to the default value. RC (Receivable Counter) is a counter whose count value is decremented when the received electric field strength of the frequency channel is equal to or less than a predetermined threshold. DBC (Data Base Counter) decrements the count value when the received electric field strength of the frequency channel is less than or equal to a predetermined threshold (except when the current position is within the reception difficult area even if it is less than or equal to the predetermined threshold). Counter. In any counter, 0 is the lower limit, and it is not decremented to a negative value. The display of the frequency channel with RC 0 is deleted from the station list, and the RDS data is deleted from the data RAM 112 for the frequency channel with DBC 0. In this embodiment, display or display erasure on the broadcast station list and deletion or maintenance of RDS data are controlled separately and independently according to the count values of the RC and DBC counters.

  FIG. 2 shows an example of the receivable station database in the DB RAM 113. In the example of FIG. 2, the PI code (frequency channel) is D301 (87.6 MHz), D302 (87.7 MHz), D303 (90.0 MHz), and D304 (90. 1 MHz) and D305 (90.2 MHz) broadcasting stations are registered in the receivable station database. At this time, RC and DBC are set to the first specified value (= 3) and the second specified value (= 5), respectively, as shown in FIG.

  In addition, the DB auxiliary RAM 114 of the microcomputer 109 backs up the content immediately before the update in the DB RAM 113 (that is, the content immediately before the latest content).

  Based on the RDS data stored in the data RAM 112 and the record of the receivable station database in the DB RAM 113, the microcomputer 109 uses a frequency channel other than RC of 0 (and Null). A broadcast station list that lists broadcast stations is created and displayed on the display screen of the display 111. Broadcast stations (frequency channels) listed in the broadcast station list are estimated to be currently receivable broadcast stations (frequency channels). A broadcasting station with the same PI code is displayed as one station. In addition, a frequency channel is displayed for a broadcasting station that does not store a PI code.

For example, in the receivable station database in the DB RAM 113, consider the case where RC of PI codes = D301 and D302 is other than 0 and NULL, and the following RDS data is stored in the data RAM 112.
PI code = D301, PS = SWR1, PTY = NEWS, TP = ON
PI code = D302, PS = SWR2, PTY = POPS, TP = OFF
In this case, for example, the broadcast station list shown in FIG. 3 is displayed on the display screen of the display 111.

[Difficulty receiving area entry processing]
FIG. 4 shows a flowchart of difficult-to-receive area entry determination processing executed by the microcomputer 109. For convenience of explanation, the processing step is abbreviated as “S” in the description and drawings in this specification. The receivable station database in the DB RAM 113 is registered with the contents shown in FIG. 2, for example.

<S1 in FIG. 4 (Processing for Obtaining Field Strength of Received Radio Wave)>
The microcomputer 109 acquires the electric field strength of the frequency channel currently being received from the S meter built in the radio signal processing circuit 103.

<S2 in FIG. 4 (Receivable Broadcast Station Decrease Determination Process)>
The microcomputer 109 determines whether or not the number of broadcasting stations (frequency channels) listed in the broadcasting station list, that is, the number of broadcasting stations (frequency channels) estimated to be currently received, has decreased by a predetermined number or more. Details of this reduction determination processing will be described later with reference to FIG. If the microcomputer 109 determines that the number of receivable broadcasting stations (frequency channels) has decreased by a predetermined number or more (S2: YES), the microcomputer 109 advances the process to S3 (entry flag entry process for difficult to receive area) in FIG. . If it is determined that the number of receivable broadcasting stations (frequency channels) has not decreased by a predetermined number or more (S2: NO), the process returns to S1 (received radio wave field strength acquisition process) in FIG.

<S3 of FIG. 4 (entry flag entry processing to difficult reception area)>
When the number of receivable broadcasting stations (frequency channels) decreases, the microcomputer 109 estimates that the broadcast receiver 1 has entered the reception difficulty area, and therefore sets a predetermined entry flag to ON.

<S4 in FIG. 4 (electric field intensity storage process)>
When the microcomputer 109 turns on the approach flag, the electric field strength of the frequency channel currently being received acquired in the processing of S1 in FIG. 4 (the received electric field strength acquisition processing) is stored in the electric field strength RAM 115 of the microcomputer 109. At the same time, the update of the backup data in the DB auxiliary RAM 114 is stopped. By stopping the update of the backup data, the data corresponding to the broadcast station list immediately before entering the difficult reception area is held in the DB auxiliary RAM 114.

[Reduction judgment processing of receivable broadcasting stations]
FIG. 5 shows a flowchart of the decrease determination process of receivable broadcasting stations in S2 of FIG.

<S101 in FIG. 5 (Receiving Electric Field Strength Acquisition Processing by Station Check Command)>
By executing the Station Check command, the microcomputer 109 acquires the electric field strength of one of the frequency channels whose DBC is other than 0 (and Null) in the receivable station database in the DB RAM 113. Here, the Station Check command means that the program being played back or recorded is temporarily muted for a very short period (for example, a very short period of about 5 ms), and another specified frequency channel is received. This is a function for detecting the electric field strength and noise level of the received radio wave and updating the broadcast station list based on the detection result. When the station list command is used to update the broadcast station list, playback of broadcast programs, etc. is intermittently interrupted according to the search period of each frequency channel (above 5 ms), but since each search period is extremely short, It is difficult for the user to perceive that the search process is being performed with playback stopped. Therefore, it can be considered that the reproduction processing of the broadcast program and the update processing of the broadcast station list are performed in parallel. Note that if the search interval for each frequency channel by the Station Check command is too short, it will be easy for the user to perceive interruptions such as playback of broadcast programs, while if the search interval is too long, it will take time to complete the execution of the Station Check command. The problem is pointed out. In view of such circumstances, in this embodiment, the search interval is set to about 1.5 s, for example.

<S102 of FIG. 5 (Receivability Determination Processing)>
The microcomputer 109 determines whether or not reception is possible based on the electric field strength of the frequency channel checked by the Station Check command. If the electric field strength of the frequency channel is greater than or equal to the predetermined threshold, the microcomputer 109 determines that the frequency channel is receivable (S102: YES), and advances the process to S103 (RC reset process) in FIG. If the electric field strength of the frequency channel is less than the predetermined threshold, the microcomputer 109 determines that the frequency channel is not receivable (S102: NO), and advances the process to S106 (RC decrement process) in FIG. The predetermined threshold value is the same as the threshold value used for, for example, stationed determination at the time of search or seek.

<S103 in FIG. 5 (RC Reset Processing)>
The microcomputer 109 resets the RC count value of the frequency channel determined to be receivable in the process of S102 of FIG. 5 (reception availability determination process) to the first specified value (= 3).

<S104 in FIG. 5 (DBC Reset Processing)>
The microcomputer 109 resets the DBC count value of the frequency channel determined to be receivable in the process of S102 of FIG. 5 (reception availability determination process) to the second specified value (= 5).

<S105 in FIG. 5 (electric field intensity storage process)>
The microcomputer 109 stores the electric field intensity of the frequency channel acquired in the process of S101 of FIG. 5 (the process of acquiring the electric field intensity of the received radio wave by the Station Check command) in the electric field intensity RAM 115, and the process is performed in S113 of FIG. Proceed to (All station check completion judgment processing).

<S106 in FIG. 5 (RC Decrement Processing)>
The microcomputer 109 decrements the RC count value of the frequency channel determined to be unreceivable in the process of S102 (reception availability determination process) in FIG. When the count value is already 0, it is not decremented.

<S107 in FIG. 5 (RC Count Value Judgment Processing)>
The microcomputer 109 determines whether or not the RC count value is zero. If the RC count value is 0 (S107: YES), the microcomputer 109 advances the process to S108 (channel information display deletion process) in FIG. If the RC count value is not 0 (S107: NO), the process proceeds to S109 (entrance flag determination process for difficult-to-receive area) in FIG.

<S108 in FIG. 5 (Channel Information Display Erase Processing)>
For the frequency channel in which the RC count value has been decremented to 0, the process of this flowchart is executed three times, and in each process of S102 (reception availability determination process) in FIG. 5 (that is, three consecutive times) reception is impossible. It has been determined. Therefore, the microcomputer 109 determines that the frequency channel that has been decremented to the RC count value of 0 is currently in a state where reception is difficult (it is not in a state that can withstand viewing by the user), and is displayed on the display screen of the display 111. Clear the display from the list of stations. Next, the microcomputer 109 advances the process to S109 (entry flag determination process for difficult to receive area) in FIG.

<S109 in FIG. 5 (entry flag determination process for difficult to receive area)>
The microcomputer 109 determines whether or not the entry flag to the difficult reception area is turned on. When the microcomputer 109 determines that the entry flag for the difficult reception area is turned on (S109: YES), the microcomputer 109 advances the process to S113 (all station check completion determination process) in FIG. If it is determined that the entry flag to the difficult reception area is not turned on (S109: NO), the process proceeds to S110 (DBC decrement process) in FIG.

<S110 in FIG. 5 (DBC decrement processing)>
If the microcomputer 109 determines that the entry flag for the difficult reception area is not turned on in the processing of S109 of FIG. 5 (entrance flag determination processing for difficult reception area), the processing of S102 of FIG. The DBC count value of the frequency channel determined to be unreceivable in the determination process) is decremented by 1. When the count value is already 0, it is not decremented.

<S111 in FIG. 5 (DBC Count Value Judgment Processing)>
The microcomputer 109 determines whether the DBC count value is zero. If the count value of DBC is 0 (S111: YES), the microcomputer 109 advances the process to S112 (channel information deletion process) in FIG. If the DBC count value is not 0 (S111: NO), the process proceeds to S113 (all station check completion determination process) in FIG.

<S112 in FIG. 5 (Channel Information Deletion Processing)>
For the frequency channel in which the DDC count value has been decremented to 0, the process of this flowchart is executed five times, and in each process of S102 in FIG. 5 (reception availability determination process) (that is, five consecutive times), reception is impossible. It has been determined. Therefore, the microcomputer 109 determines that it is difficult to decode the RDS data for the frequency channel whose DBC count value has been decremented to 0, and stores the RDS data of the frequency channel stored in the data RAM 112. Is deleted. Next, the microcomputer 109 advances the processing to S113 (all station check completion determination processing) in FIG.

<S113 in FIG. 5 (all station check completion determination process)>
The microcomputer 109 performs the process of S101 in FIG. 5 (electric field strength acquisition processing of the received radio wave by the Station Check command) for all frequency channels whose DBC is other than 0 (and Null) in the receivable station database in the DB RAM 113. ) Etc. are determined. If the microcomputer 109 determines that the process of S101 in FIG. 5 (the process for obtaining the electric field intensity of the received radio wave by the Station Check command) or the like has been executed for all the frequency channels (S113: YES), the process is as shown in FIG. The process proceeds to S114 (decrease determination process). If unexecuted frequency channels remain (S113: NO), the processing returns to the processing of S101 in FIG. 5 (reception radio wave field strength acquisition processing by the Station Check command), and the subsequent frequency channels are processed after S101. Execute the process.

<S114 in FIG. 5 (decrease determination processing)>
The microcomputer 109 includes a receivable station database in the DB RAM 113 (corresponding to the latest broadcast station list) and a receivable station database in the DB auxiliary RAM 114 (broadcast stations having contents one before the latest contents). To determine whether or not the number of frequency channels listed in the broadcast station list has decreased by a predetermined number or more. More specifically, the number of frequency channels other than RC 0 (and Null) in the receivable station database in the DB RAM 113 is RC, and RC is 0 (and Null) in the receivable station database in the DB auxiliary RAM 114. It is determined whether or not the number of frequency channels other than is reduced by a predetermined number or more. When the microcomputer 109 determines that the number of frequency channels listed in the broadcast station list has decreased by a predetermined number or more (S114: YES), the microcomputer 109 performs the process of S2 in FIG. 4 (reduction determination process of receivable broadcast stations). YES is determined. If it is determined that the number of frequency channels listed in the broadcast station list has not decreased by a predetermined number or more (S114: NO), NO is determined in the process of S2 in FIG. 4 (reduction determination process of receivable broadcast stations). Make a decision. In this reduction determination process, instead of or in addition to the reduction number of receivable frequency channels, the reduction determination may be performed based on the reduction rate of receivable frequency channels.

  If the decrement processing of DBC is allowed in the same manner as RC during the period in which the broadcast receiver 1 is located in the difficult reception area (that is, the period in which it is determined that the frequency channel cannot be received), all frequency channels become DBC = 0. The RDS data of all frequency channels in the data RAM 112 may be deleted. In this case, since there is no information constituting the broadcast station list, it is impossible to promptly display or update the broadcast station list, for example, when the broadcast station list is escaped.

  Therefore, in the present embodiment, as shown in the description of the processing of S109 to S112 in FIG. 5, when the current position is within the difficult reception area (when the entry flag to the difficult reception area is turned on), the reception is performed. Regardless of the state, the processing of S110 in FIG. 5 (DBC decrement processing) is skipped. Therefore, even if the display of the frequency channel determined to be unreceivable during the period in the difficult reception area is deleted from the broadcast station list, the RDS data in the data RAM 112 is not deleted. Retained. Therefore, for example, immediately after exiting from the difficult reception area, the broadcast station list can be displayed or updated based on the RDS data stored in the data RAM 112.

[Update example of receivable station database in DB RAM 113]
An example of updating the receivable station database in the DB RAM 113 when the decrease determination process in FIG. 5 (S2 in FIG. 4) is executed will be described with reference to FIGS. 2 and 6A to 6D. To do. The receivable station database in the DB RAM 113 receives D301 (87.6 MHz) and D303 (90.0 MHz) in the process of S102 of FIG. 5 (reception availability determination process) based on the contents shown in FIG. Is determined to be impossible, these RCs are decremented by 1 in the process of S106 in FIG. 5 (RC decrement process) (see FIG. 6A).

  Next, due to the deterioration of the reception environment, all RCs and DBCs are decremented twice consecutively in the process of S106 (RC decrement process) and the process of S110 (DBC decrement process) in FIG. Then, the contents are updated to the contents shown in FIG. At this time, the display of D301 (87.6 MHz) and D303 (90.0 MHz) is deleted from the broadcast station list on the display screen of the display 111.

  After that, when it is determined that it has entered the difficult reception area and all frequency channels cannot be received, the remaining RCs of D302 (87.7 MHz), D304 (90.1 MHz), and D305 (90.2 MHz) are 0. The information of any broadcasting station is not displayed in the broadcasting station list on the display screen of the display 111. On the other hand, for DBC, the processing of S110 in FIG. 5 (DBC decrement processing) is skipped, so D301 (87.6 MHz), D302 (87.7 MHz), D303 (90.0 MHz), D304 (90. Neither RDS data of 1 MHz) nor D305 (90.2 MHz) is deleted from the data RAM 112 (see FIG. 6C). Therefore, for example, when the station check command is executed for each PI code (frequency channel) when it is determined that reception is possible when exiting the difficult reception area, the broadcast station list is based on the RDS data. Can be reconfigured. FIG. 6D shows a state in which each frequency channel is determined to be receivable, and RC and DBC are reset to specified values, respectively.

[Hard reception area escape judgment processing]
Next, the difficult-to-receive area escape determination process executed by the microcomputer 109 will be described with reference to FIG. The process of this flowchart is started when the entry flag to the difficult reception area is turned on.

<S201 in FIG. 7 (Power Supply Flag ON Processing)>
The microcomputer 109 turns on a predetermined power supply flag. This power flag is set to off when the engine (or ACC power) is turned off and on even once after execution of the power flag on process.

<S202 of FIG. 7 (Receiving radio wave field strength acquisition process)>
The microcomputer 109 acquires the electric field strength of the frequency channel currently being received from the S meter built in the radio signal processing circuit 103.

<S203 in FIG. 7 (electric field strength determination process)>
The microcomputer 109 stores the electric field intensity of the received radio wave (immediately before entering the difficult reception area) stored in the electric field intensity RAM 115 in the process of S4 (electric field intensity storage process) in FIG. The received electric field intensity of the received radio wave acquired in the process (received electric field intensity acquisition process) is compared, and it is determined whether or not the latter electric field intensity is higher than the former electric field intensity by a predetermined value or more. If the microcomputer 109 determines that the latter is higher than the former by a predetermined value (S203: YES), the microcomputer 109 estimates that the reception environment has improved and advances the process to S204 (entry flag entry process for difficult to receive area). . When it is determined that the latter is not a value higher than the specified value than the former (S203: NO), it is estimated that the reception environment has not improved, and the process returns to S202 (reception wave field strength acquisition process) in FIG. . The specified value may be a fixed value (for example, about 6 dB), and is stored in the field strength RAM 115 in the process of S4 (field strength storage process) in FIG. It may be a variable value corresponding to the electric field strength of the received radio wave (immediately before). Further, the specified value may be determined based on the transition of the electric field strength for a predetermined period before entering the difficult reception area. However, in this case, it is necessary to constantly monitor the electric field strength.

<S204 in FIG. 7 (entry flag off process for difficult to receive area)>
The microcomputer 109 estimates that the reception environment has been improved by escaping from the difficult reception area, and sets the entry flag to the difficult reception area to OFF.

  Thus, in this embodiment, entry / exit with respect to an area where it is difficult to receive is determined based on the change (decrease number) in the frequency channel listed in the broadcast station list and the change (increase amount) in the field strength of the received radio wave. Therefore, the broadcast receiver 1 does not need to include a dedicated device for determining whether or not the current position is within the difficult reception area, and has a configuration that is advantageous for cost reduction. Further, since the escape from the difficult reception area is determined only by the increase amount of the electric field strength, the processing load is light. Therefore, the broadcast receiver 1 has an advantageous configuration for promptly displaying the broadcast station list after exiting the difficult reception area.

<S205 in FIG. 7 (Power Supply Flag Determination Process)>
The microcomputer 109 determines whether or not the power flag turned on in the process of S201 (power flag on process) in FIG. 7 remains on. If the power supply flag remains on (S205: YES), the microcomputer 109 advances the process to S206 (broadcast station list update process). When the power flag is turned off when the engine (or ACC power) is turned off and on (S205: NO), the process proceeds to S207 (broadcast station list recreating process) in FIG.

<S206 in FIG. 7 (Broadcasting station list update processing)>
In the microcomputer 109, the engine (or ACC power supply) was not turned off and on during the period in which it was located in the difficult reception area, so the difficult reception area is an area where the vehicle moves, such as a tunnel. Estimated. In this case, there is a possibility that the reception environment is greatly different (for example, the broadcast area is different) when entering or leaving the difficult reception area. Therefore, the microcomputer 109 sets the search interval for each frequency channel to be shorter (for example, set to an interval shorter than 1.5 s) compared to the Station Check command executed at other timings, and stores in the DB RAM 113. The Station Check command is executed for all frequency channels whose DBC is not 0 (and Null) in the receivable station database. Further, the microcomputer 109 may execute channel search processing for all reception frequencies in the FM band and reacquire RDS data of receivable frequency channels.

<S207 in FIG. 7 (broadcast station list re-creation processing)>
In the microcomputer 109, the engine (or the ACC power supply) was turned off and on during the period in which it was located in the difficult reception area. It is estimated that the area was not accompanied by. In this case, there is a high possibility that the reception environment does not change when entering or leaving the difficult reception area. Therefore, the microcomputer 109 recreates the broadcast station list based on the data corresponding to the broadcast station list immediately before entering the difficult reception area, which is backed up in the DB auxiliary RAM 114. Thereby, the microcomputer 109 can promptly display the broadcast station list without executing the Station Check command or the channel search process. Further, the microcomputer 109 replaces the broadcast station list based on the backup data in the DB auxiliary RAM 114 with all the frequency channels other than 0 (and Null) DBC in the receivable station database in the DB RAM 113. The station check command may be executed on the target, and the broadcast station list may be created based on the execution result.

  The above is the description of the exemplary embodiments of the present invention. Embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical idea of the present invention. For example, the embodiment of the present application also includes contents appropriately combined with examples and the like clearly shown in the specification or obvious examples.

  For example, the broadcast receiver according to the present invention is not limited to one tuner system exemplified in the present embodiment, and is also applied to other systems that do not have a dedicated tuner for updating the broadcast station list, such as a phase tuner system. be able to. In the case of the phase tuner system, the same processing as in the flowcharts shown in FIGS. 4, 5 and 7 is executed, but more specifically, the processing of S101 in FIG. ) Instead of phase diversity, the reception frequency is changed at the sub-tuner while continuing reception at the main tuner, and the process of obtaining the electric field strength of the received radio wave in a short time is the same as the Station Check command. Executed.

DESCRIPTION OF SYMBOLS 1 Broadcasting receiver 101 Antenna 102 Tuner 103 Radio signal processing circuit 104 Audio signal processing circuit 105 Power amplifier 106 Speaker 107 RDS demodulator 108 PLL circuit 109 Microcomputer 110 Input interface 111 Display 112 RAM for data
113 DB RAM
114 DB auxiliary RAM
115 Field strength RAM

Claims (8)

An entry determination means for determining whether or not the vehicle has entered an area where reception is difficult based on the number of receivable frequency channels;
Reception strength storage means for storing the reception strength of the frequency channel being received when it is determined that the vehicle has entered the difficult reception area;
A comparison means for comparing the reception intensity stored by the reception intensity storage means with the reception intensity of the currently received frequency channel;
Escape determination means for determining whether or not the vehicle has escaped from the difficult reception area based on a comparison result by the comparison means;
A broadcast receiver comprising: The escape determination means includes
2. The method according to claim 1, wherein when the reception intensity of the frequency channel currently being received is higher than a reception intensity stored by the reception intensity storage unit by a predetermined value or more, it is determined that the area has escaped from the difficult reception area. The broadcast receiver described. Storage means for storing a channel list;
Updating means for updating the channel list based on the reception state of the frequency channel;
With
The updating means includes
The broadcast receiver according to claim 1 or 2, wherein updating of the channel list is stopped during a period in which the reception is difficult. Connected to the mobile ACC power supply,
Detecting means for detecting on / off of the ACC power source;
Display control means for controlling the display of the channel list on a predetermined display screen based on the detection result of the detection means;
The broadcast receiver according to any one of claims 1 to 3, further comprising: The display control means includes
When ON / OFF of the ACC power source is detected by the detection means during a period located in the reception difficulty area, the reception difficulty area is determined when the escape determination means determines that the vehicle has escaped from the reception difficulty area. 5. The broadcast receiver according to claim 4, wherein the same channel list as when entering the channel is displayed on the display screen. The display control means includes
When the detection means does not detect the on / off of the ACC power supply during a period located in the difficult-to-receive area and the escape determining means determines that it has escaped from the difficult-to-receive area, the update The broadcast receiver according to claim 4 or 5, wherein the channel list updated after the escape is displayed on the display screen. The updating means includes
When the detection means does not detect the on / off of the ACC power source during the period located in the difficult reception area, and the escape determination means determines that the escape is difficult, the reception The broadcast receiver according to claim 6, wherein an interval for checking a reception state of each frequency channel is shortened compared to a time other than when the escape from the difficult area is performed. An entry determination step for determining whether or not an entry is made in an area where reception is difficult based on the number of receivable frequency channels;
A reception strength storage step of storing the reception strength of the frequency channel being received when it is determined that the vehicle has entered the difficult reception area;
A comparison step of comparing the reception strength stored in the reception strength storage step with the reception strength of the currently received frequency channel;
An escape determination step for determining whether or not the vehicle has escaped from the difficult reception area based on a comparison result in the comparison step;
A reception difficulty area determination method.

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