JP2015050515A - Broadcast receiver and alternative station search method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a broadcast receiver and alternative station search method, capable of appropriately presenting a receivable alternative station in a frequency bandwidth including a selected reception frequency.SOLUTION: The present invention comprises a controller 7 that controls a third reception section 2-3 to perform an alternative station search in a frequency bandwidth including a reception frequency when the reception electric field strength of a broadcast wave is determined to have changed beyond a predetermined range during reception of a broadcast wave of a reception frequency by a first and a second reception sections 2-1, 2-2.

Description

  The present invention relates to a broadcast receiving apparatus and an alternative station search method that are mounted on a moving body such as a vehicle and receive a broadcast.

  In a conventional broadcast receiving apparatus, for example, in the case of radio broadcasting, each of the FM, AM, SW (short wave), and LW (long wave) is received in order to constantly acquire and update a receivable broadcast station and traffic information. The frequency band is searched in order. This search result is stored in the storage device as an alternative station list for each frequency band, and the user is presented with an alternative station list in the frequency band currently receiving the broadcast. Thereby, when the reception state of the currently received broadcast is deteriorated, a receivable alternative station can be selected from the alternative station list.

  For example, Patent Document 1 discloses a first receiving unit that receives a broadcast wave and a second receiving unit that receives a broadcast wave of an alternative station in a receivable frequency band while the first receiving unit is receiving a broadcast. Is disclosed. In this receiver, the reception state of the broadcast wave currently being received by the first reception unit is maintained, and the reception state of the broadcast wave from the alternative station included in the receivable frequency band is checked by the second reception unit. Can do.

JP 2001-15662 A

  In the conventional technique represented by Patent Document 1, when the reception electric field strength of a broadcast that is currently being received changes suddenly, the reception state of the frequency band that is receiving the broadcast deteriorates and is presented to the user There is a possibility that an alternative station in the station list cannot be received. In this case, it is necessary to search for an alternative station in the frequency band in which the broadcast was received and update the alternative station list.

However, when the received electric field strength of the currently received broadcast suddenly changes, the search is not necessarily made for alternative stations in that frequency band, and alternative station searches for each frequency band are sequentially performed.
For this reason, there is a problem that it may take a long time until an alternative station in a desired frequency band is searched and the alternative station list is updated.

In addition, when an alternative station search of another frequency band has been performed, an operation for instructing an alternative station search of a desired frequency band is required, which causes trouble.
Furthermore, if the broadcast content broadcast only at a specific location such as a tunnel is received, the reception status of the broadcast being received is not degraded, but the reception status in the frequency band of the alternative station list may be degraded. There is sex. In this case, a list of alternative stations that cannot actually be received is presented to the user.

  The present invention has been made to solve the above-described problems, and a broadcast receiving apparatus and an alternative station search capable of accurately presenting an alternative station that can be received in a frequency band including a selected reception frequency. The purpose is to obtain a method.

  The broadcast receiving apparatus according to the present invention includes a plurality of receiving units, receives a broadcast wave having a selected reception frequency at a part of the plurality of receiving units, and receives the other of the plurality of receiving units. The broadcast receiving apparatus that performs an alternative station search for checking whether there is a broadcast wave of an alternative station that can be received in each frequency band by the receiver, and presents an alternative station in a frequency band that includes the received frequency, and a part of the receiver If it is determined that the received electric field strength of the broadcast wave has fluctuated beyond the specified range when receiving a broadcast wave of the reception frequency in, another reception is performed so that an alternative station search is performed in the frequency band including the reception frequency. The control part which controls a part is provided.

  According to the present invention, there is an effect that an alternative station that can be received in a frequency band including a selected reception frequency can be accurately presented.

It is a block diagram which shows the structure of the broadcast receiver which concerns on Embodiment 1 of this invention. 3 is a flowchart showing an operation of the broadcast receiving apparatus according to the first embodiment. It is a figure which shows the example of a screen which displayed the channel selection received frequency and the frequency of the alternative station. 6 is a block diagram illustrating another configuration of the broadcast receiving apparatus according to Embodiment 1. FIG. It is a block diagram which shows the structure of the broadcast receiver which concerns on Embodiment 2 of this invention. 10 is a flowchart showing an operation (history information storage) of the broadcast receiving apparatus according to the second embodiment. 10 is a flowchart showing an operation (alternative station list update) of the broadcast receiving apparatus according to the second embodiment. It is a flowchart which shows operation | movement of the broadcast receiver which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the broadcast receiver which concerns on Embodiment 4 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a broadcast receiving apparatus according to Embodiment 1 of the present invention. In FIG. 1, a broadcast receiving apparatus 1 is brought into or mounted on a mobile body (for example, a vehicle), and is a broadband broadcast capable of receiving broadcast waves in each frequency band of FM, AM, SW (short wave), and LW (long wave). It is a receiving device. As its configuration, antennas 2a and 2b, first receiving unit 2-1, second receiving unit 2-2, third receiving unit 2-3, PD (phase diversity) control unit 3, and demodulating units 4a and 4b. , Signal meters 5a and 5b, RDS (radio data system) demodulation units 6a and 6b, a control unit 7, an amplifier unit 8, a speaker 9, a display unit 10, an operation unit 11 and a storage unit 12.

The first receiving unit 2-1 includes a front end unit 20a, a BPF (band pass filter) 21a, an IF (intermediate frequency) filter 22a, and an IF amplifier 23a.
The second receiving unit 2-2 includes a front end unit 20b, a BPF 21b, an IF filter 22b, and an IF amplifier 23b.
The third reception unit 2-3 includes a front end unit 20c, a BPF 21c, an IF filter 22c, and an IF amplifier 23c.

The front end units 20a, 20b, and 20c receive the frequency setting signal from the control unit 7, and select and amplify the reception frequency indicated by the frequency setting signal from the RF (high frequency) signals received via the antennas 2a and 2b. After that, the frequency is converted to IF signal.
In the broadcast receiving apparatus 1 shown in FIG. 1, the front end units 20a and 20b receive the broadcast wave of the reception frequency selected by the user, and the front end unit 20c broadcasts the frequency of the alternative station search target frequency. Receive waves.

The BPFs 21a, 21b, and 21c are band-pass filters that band-limit IF signals frequency-converted by the front end units 20a, 20b, and 20c.
The IF filters 22a, 22b, and 22c are band pass filters that limit the IF signal that has passed through the BPFs 21a, 21b, and 21c to a predetermined band expected as a modulation signal.
The IF amplifiers 23a, 23b, and 23c are amplifiers that amplify the IF signal that has passed through the IF filters 22a, 22b, and 22c.

  The PD control unit 3 is a control unit that performs a phase synthesis process on outputs from the first reception unit 2-1 and the second reception unit 2-2. That is, the broadcast receiving apparatus 1 has a phase diversity function using the first receiving unit 2-1 and the second receiving unit 2-2, and in the receiving units 2-1 and 2-2, the user Only the broadcast wave of the reception frequency selected by is received.

The demodulator 4 a is a demodulator that demodulates the received signal that has been phase-combined by the PD controller 3. The demodulator 4b demodulates the IF signal amplified by the IF amplifier 23c.
Note that the audio signal demodulated by the demodulator 4 a is amplified by the amplifier 8 and output from the speaker 9.

The signal meter 5 a is a signal meter that measures the received electric field strength of the received signal that is phase-combined by the PD control unit 3.
The signal meter 5b measures the received electric field strength of the received signal output from the IF amplifier 23c of the third receiving unit 2-3.

The RDS demodulator 6a is an RDS demodulator that demodulates, synchronizes, and corrects errors of the RDS data in the demodulated signal output from the demodulator 4a.
The RDS demodulator 6b is an RDS demodulator that demodulates, synchronizes, and corrects errors of the RDS data in the demodulated signal output from the demodulator 4b.

The control unit 7 is a control unit that controls the entire broadcast receiving apparatus 1 by incorporating a microcomputer and a memory that stores data necessary for arithmetic processing.
In addition, the control unit 7 receives the broadcast wave having the reception frequency at the first reception unit 2-1 and the second reception unit 2-2, and the received electric field strength of the broadcast wave is a predetermined time. When it is determined that a predetermined variation condition is satisfied within the range, the third reception unit 2-3 is controlled to perform an alternative station search in a frequency band including the reception frequency. The predetermined time range and variation conditions will be described later.

  The display unit 10 is a display unit that displays display information input from the control unit 7, and includes, for example, a liquid crystal display, an organic EL (Electro-Luminescence) panel, and the like. The display unit 10 provides a UI (User Interface) for inputting operation information (a reception frequency selected by the user) using the operation unit 11 under the control of the control unit 7. The reception frequency selected by the user and the frequency of the alternative station in the frequency band including the reception frequency are displayed on the display unit 10.

The operation unit 11 is an operation unit that receives a user's operation input, and is realized by, for example, a touch panel provided on the screen of the display unit 10, a hardware key, an input unit that uses voice recognition, and the like.
The storage unit 12 is a storage unit that stores the result of the alternative station search (substitute station list) by the third reception unit 2-3.

  In general, the search time for each frequency band is about 15 seconds for FM and about 30 seconds for AM, SW, and LW. In the conventional broadcast receiving apparatus, for example, the received electric field strength suddenly changes during reception of FM broadcast, and any broadcast in the alternative station list presented to the user in the FM frequency band cannot be received. Sometimes, when the third receiver 2-3 performs an alternative station search for the AM frequency band, the FM frequency band is searched for an alternative station, and the search time for each frequency band is updated until the alternative station list is updated. You have to wait for the combined time. Thus, there was a problem that the alternative station that could not be received remained presented for a long time.

  Therefore, in the present invention, the control unit 7 sets the reception frequency when the reception electric field strength of the broadcast wave suddenly changes while the reception unit 2-1 and 2-2 are receiving the broadcast wave of the reception frequency. The third receiver 2-3 is controlled so as to perform an alternative station search in the included frequency band. By doing in this way, the alternative station which can be received in the frequency band containing the receiving frequency selected by the user can be shown exactly.

Next, the operation will be described.
FIG. 2 is a flowchart showing the operation of the broadcast receiving apparatus according to the first embodiment. The alternative station search and the process of updating the alternative station list according to the result will be described with reference to FIG.
First, the third receiving unit 2-3 performs an alternative station search for each frequency band receivable by the broadcast receiving device 1 in a predetermined order regardless of the reception frequency bands of the receiving units 2-1 and 2-2 (steps). ST1). The broadcast receiving apparatus 1 is a wideband broadcast receiving apparatus capable of receiving broadcast waves in each frequency band of FM, AM, SW (short wave), and LW (long wave), and the third receiving unit 2-3 includes The presence / absence of broadcast waves of an alternative station with good reception (receivable) at each frequency in the order of FM, AM, SW, and LW is checked.

The control unit 7 periodically acquires the received electric field strength detected by the signal meter 5a, and based on the received electric field strength, the received electric field strength of the broadcast wave received by the receiving units 2-1 and 2-2 is determined. It is determined whether or not there has been a sudden change (step ST2).
Here, the sudden change in the received electric field strength is determined by whether or not the received electric field strength of the broadcast wave satisfies a predetermined fluctuation condition within a predetermined time range. For example, the time advances in the order of t0, t1, t2 (ms), the reception electric field strength of the broadcast wave at time t is Lv (t) (dBuV), and the amount of variation indicating a sudden change in the reception electric field strength is Lev_X. A threshold value indicating the upper limit of the impossible received electric field strength is assumed to be Lev_Y. In this case, it is determined that the received electric field strength has suddenly changed when all the fluctuation conditions of the following formula (1) are satisfied.
| Lv (t1) −Lv (t0) | ≧ Lev_X
| Lv (t2) −Lv (t0) | ≧ Lev_X
Lv (t0) ≦ Lev_Y (1)

However, in the above formula (1), it is preferable that the time interval indicated by t2-t0 is a time equal to or shorter than the shortest search time among the alternative station search times of each frequency band. For example, if the FM alternative station search time is 15 seconds, t2-t0 is set to 15 seconds or less.
By doing so, it is possible to immediately switch to the alternative station search in the frequency band including the frequency of the broadcast currently being received without waiting for the alternative station search in any frequency band to end.

When it is determined that the received electric field strength has not changed suddenly (step ST2; NO), the process returns to step ST1 and the above-described processing is repeated.
On the other hand, when it is determined that the received electric field strength has suddenly changed (step ST2; YES), the control unit 7 is receiving the current broadcast by the third receiving unit 2-3 at the receiving units 2-1 and 2-2. It is confirmed whether an alternative station search is performed in the frequency band (step ST3). For example, if the receiving units 2-1 and 2-2 are receiving FM broadcasts, it is confirmed whether the third receiving unit 2-3 is performing an alternative station search in the FM frequency band.

  When the alternative station search is not performed in the frequency band in which the receiving units 2-1 and 2-2 are currently receiving the broadcast (step ST3; NO), the control unit 7 sends the third receiving unit 2-3 to the third receiving unit 2-3. An instruction is issued to stop the alternative station search (step ST4). Thereafter, the control unit 7 instructs the third receiving unit 2-3 to perform a substitute station search by switching to the frequency band in which the receiving units 2-1 and 2-2 are currently receiving the broadcast. As a result, the third receiver 2-3 performs an alternative station search for the frequency band in which the receivers 2-1 and 2-2 are currently receiving the broadcast (step ST5).

When the alternative station search has been performed in the frequency band in which the receiving unit 2-1 and 2-2 is currently receiving the broadcast (step ST3; YES), or when the alternative station search in step ST5 is completed, the control unit 7 obtains the result of the alternative station search by the third receiver 2-3.
Next, based on the alternative station search result of the third receiving unit 2-3, the control unit 7 replaces the alternative station list (substitution in the frequency band currently receiving the broadcast by the receiving units 2-1 and 2-2. The station list is updated (step ST6).
In addition, although the case where the result of the alternative station search performed in the frequency band currently received was acquired was shown, even if the alternative station search was performed in the frequency band currently received, the result is It may be canceled once and a new search is performed to obtain the result.

  When the FM broadcast is received by the receiving units 2-1 and 2-2, the display screen 10 a of the display unit 10 has a reception frequency at which the current broadcast is received as shown in FIG. 3A, for example. 10b is displayed, and an alternative station list 10c of the frequency band of FM is displayed. Here, the received electric field strength suddenly changes, and reception at a frequency of 82.5 MHz becomes impossible. At this time, if the third receiving unit 2-3 performs an alternative station search in the AM frequency band, conventionally, As described above, it has been necessary to wait until the search of the other frequency band is completed for the update of the alternative station list 10c of the FM frequency band. For this reason, before the alternative station list is updated, the broadcast cannot be received even if the user selects a frequency of 78.0 MHz (indicated by an arrow in the figure) displayed in the alternative station list. In addition, it may be necessary to re-select other receivable stations.

In contrast, in the present invention, when a sudden change in the received electric field strength is detected, the receiving units 2-1 and 2-2 immediately switch to the alternative station search in the frequency band in which the broadcast is currently received.
By doing in this way, it is possible to accurately present an alternative station in a frequency band including the reception frequency selected by the user without waiting for completion of an alternative station search in another frequency band.
Further, the display screen of FIG. 3 is merely an example, and all alternative stations may be displayed by pull-down or the like.

Although FIG. 1 shows the case where the broadcast of the frequency selected by the user is received by the receiving units 2-1 and 2-2 with phase diversity, the present invention is not limited to this.
For example, as shown in FIG. 4, a broadcast receiving device 1 </ b> A that receives a broadcast of a frequency selected by a user only by the first receiving unit 2-1 may be used. In this case, the PD control unit 3 is omitted, and the control unit 7A periodically obtains the received electric field strength detected by the signal meter 5a, and based on the received electric field strength, the first receiving unit 2-1 It is determined whether or not the received electric field strength of the broadcast wave being received has changed suddenly.

As described above, according to the first embodiment, when the first and second receiving units 2-1 and 2-2 receive broadcast waves of the reception frequency, the reception electric field strength of the broadcast waves is predetermined. When it is determined that the frequency fluctuates beyond the range, the control unit 7 is provided to control the third reception unit 2-3 so that an alternative station search is performed in a frequency band including the reception frequency.
By comprising in this way, the alternative station which can be received in the frequency band containing the receiving frequency selected by the user can be shown exactly.

Embodiment 2. FIG.
FIG. 5 is a block diagram showing a configuration of a broadcast receiving apparatus according to Embodiment 2 of the present invention. As shown in FIG. 5, the broadcast receiving apparatus 1B according to the second embodiment includes a GPS (Global Positioning System) antenna 13a and a GPS receiving unit 13 added to the configuration shown in FIG. 1 in the first embodiment. A control unit 7B is provided instead of the control unit 7, and a storage unit 12A is provided instead of the storage unit 12.
Similarly to the first embodiment, the broadcast receiving apparatus 1B is brought into or mounted on a mobile body (for example, a vehicle), and is a broadband broadcast capable of receiving broadcast waves in each frequency band of FM, AM, SW, and LW. It is a receiving device.

When the control unit 7B determines that the broadcast receiving device 1B is in the area including the point of the history information from the position information when the reception units 2-1 and 2-2 are receiving broadcast waves of the reception frequency, The third receiving unit 2-3 is controlled so that the alternative station search is performed in the frequency band including the reception frequency without determining the fluctuation of the reception electric field strength of the broadcast wave.
The storage unit 12A is a storage unit that stores, as history information, points where an alternative station search has been performed in the past. For example, a point (latitude and longitude) where an alternative station search has been performed in the past and a predetermined range area including this point are used as history information.

The GPS receiver 13 is a position information acquisition unit that acquires position information of the broadcast receiving device 1B.
For example, the position information of the broadcast receiving apparatus 1B is acquired by analyzing GPS radio waves received from GPS satellites via the GPS antenna 13a. In addition, when the broadcast receiving device 1B is mounted on the vehicle, the position information may be acquired using a gyro output and a vehicle speed pulse of a vehicle speed sensor in addition to the GPS.

Next, the operation will be described.
FIG. 6 is a flowchart showing the operation of the broadcast receiving apparatus according to the second embodiment, and processing for storing history information will be described with reference to this figure. Note that the processing from step ST1a to step ST6a in FIG. 6 is the same as that from step ST1 to step ST6 shown in FIG.

When the control unit 7B updates the alternative station list, based on the position information acquired by the GPS receiving unit 13, the point (latitude and longitude) where the alternative station search is performed and the area in a predetermined range including this point are used as history information. It memorize | stores in the memory | storage part 12A (step ST7a).
The predetermined range that defines the area is preferably a range that includes a reception environment (tunnel, indoor parking lot, etc.) in which the received electric field intensity is varied. For example, several hundreds centered on a point where an alternative station search was performed. Set the meter range.

FIG. 7 is a flowchart showing the operation of the broadcast receiving apparatus according to the second embodiment, and an alternative station list update process using history information will be described with reference to this figure.
First, the control unit 7B inputs the position information acquired by the GPS receiving unit 13 at a predetermined cycle, and confirms whether or not the current position is within the history information area of the storage unit 12A (step ST1b). . The predetermined period for inputting the position information, that is, the period for performing the confirmation is preferably a time interval equal to or shorter than the shortest search time among the alternative station search times of each frequency band. Thus, it is possible to immediately switch to the alternative station search in the frequency band including the frequency of the currently received broadcast without waiting for the alternative station search in any frequency band to end.

When the current position is not within the history information area (step ST1b; NO), the control unit 7B repeats the process of step ST1b. However, at this time, the control unit 7B periodically acquires the received electric field strength detected by the signal meter 5a, and broadcast waves received by the receiving units 2-1 and 2-2 based on the received electric field strength. It is determined whether or not the received electric field strength has suddenly changed.
Accordingly, when it is determined that the received electric field strength has not changed suddenly, the process of step ST1b is performed. If it is determined that the received electric field strength has changed suddenly, the same processing as that in the first embodiment (processing after step ST3 in FIG. 2) is performed.

  When it is determined that the current position is within the history information area (step ST1b; YES), the control unit 7B is moving in a reception environment area (tunnel, indoor parking lot, etc.) in which the received electric field strength changes suddenly. It is possible to determine the frequency band in which the broadcast is currently received by the receivers 2-1 and 2-2 with respect to the third receiver 2-3 without determining the fluctuation of the reception electric field strength of the broadcast wave. Instructs to switch and perform an alternative station search. As a result, the third receiver 2-3 performs an alternative station search for the frequency band in which the receivers 2-1 and 2-2 are currently receiving the broadcast (step ST2b).

  Next, based on the result of the alternative station search by the third receiving unit 2-3, the control unit 7B determines the alternative station list (the frequency band currently received by the receiving units 2-1 and 2-2). The alternative station list is updated (step ST3b). In this way, for stations where the received electric field strength has suddenly changed in the past, an alternative station search including the reception frequency of the currently received broadcast is immediately performed without determining the fluctuation of the received electric field strength of the broadcast wave. Is called. Thereby, the alternative station which can be received in the frequency band including the reception frequency selected by the user can be accurately presented.

  In addition to the point (latitude and longitude) where the alternative station search is performed and the area of a predetermined range including this point, the alternative station list obtained by the alternative station search may be stored in the storage unit 12 as history information. In this case, if the current position is in the history information area and the alternative station list of the history information is an alternative station list in the frequency band of the currently received broadcast, the alternative station list is updated with this list.

  As described above, according to the second embodiment, the GPS receiving unit 13 that acquires the position information and the storage unit 12A that stores the place where the alternative station search is performed as history information are provided. When the receiving units 2-1 and 2-2 are receiving broadcast waves of the reception frequency, if it is determined from the position information that the broadcast receiving device 1B is within the area including the point of the history information, the received electric field of the broadcast waves The third receiver 2-3 is controlled so that the alternative station search is performed in the frequency band including the reception frequency without determining the fluctuation in intensity. By doing in this way, the alternative station which can be received in the frequency band containing the receiving frequency selected by the user can be shown exactly.

Embodiment 3 FIG.
The broadcast receiving apparatus according to Embodiment 3 has the same basic configuration (FIG. 1 or FIG. 2) as Embodiment 1, but changes in received electric field strength from the reception status of third receiving section 2-3. It is different in judging. Therefore, in the third embodiment, FIG. 1 is referred to for the configuration of the apparatus, and a reception field strength determination method unique to the third embodiment will be described below.

FIG. 8 is a flowchart showing the operation of the broadcast receiving apparatus according to the third embodiment. The alternative station search and the process of updating the alternative station list according to the result will be described with reference to FIG.
However, the processing from step ST1c to step ST6c is the same as the processing from step ST1 to step ST6 in FIG.

In the third embodiment, when it is determined that the received electric field strength has not changed suddenly (step ST2c; NO), the control unit 7 compares the previous alternative station search result by the third receiving unit 2-3 and the current time. The comparison is made, and it is determined from the result whether or not the received electric field intensity has suddenly changed (step ST7c).
For example, in a specific area such as a tunnel, AM traffic information is broadcast inside the tunnel, and the same broadcast can be received outside the tunnel.
Therefore, even if a vehicle equipped with its own device 1 enters the tunnel, if the receiving units 2-1 and 2-2 receive traffic information from outside the tunnel, the traffic information is also broadcast inside the tunnel. The received electric field strength (detected value of the signal meter 5a) does not decrease. For this reason, even if the reception electric field strength of other broadcasts (alternative stations) in the AM frequency band is suddenly changed (rapidly decreased), this can be detected in the reception state of the reception units 2-1 and 2-2. Can not.

Therefore, in the third embodiment, the variation in the received electric field strength is determined from the reception status of the third reception unit 2-3 according to the following equation (2). Here, List is the number of alternative stations in the alternative station list, and P (x) is the number of alternative stations that are equal to or greater than the first threshold x (dBuV) of the received electric field strength that can be received in the previous alternative station list. It is.
In addition, PC (x, y) is a list of alternative stations that were equal to or lower than the first threshold value x (dBuV) in the current alternative station list, but this time are equal to or lower than the second threshold value y (dBuV). Is a number.
It is assumed that x> y.
Furthermore, the designated station number is the number of alternative stations to be presented as the alternative station list, and the designated station number ratio corresponds to, for example, a reduction rate of alternative stations that should be allowed in the previous time and this time.
List ≧ specified station number and PC (x, y) / P (x) ≧ specified station number ratio (2)

If the control unit 7 determines that the received electric field strength has not changed suddenly from the reception status of the receiving units 2-1 and 2-2, the control unit 7 immediately determines the received electric field strength of the broadcast wave of the alternative station detected by the signal meter 5b. Then, according to the relationship of the above formula (2), the result of the alternative station search is compared with the previous time and this time. Here, the previous time is the oldest of the two most recent searches, and this time is the newer one.
In addition, this comparison uses a list of alternative stations in the frequency band for which the current search has already been completed, regardless of the frequency band of the broadcast received by the receiving units 2-1 and 2-2.
For example, when AM traffic information is received by the receiving units 2-1 and 2-2, when the third receiving unit 2-3 has completed the two most recent alternative station searches for FM The above comparison is performed using the list of alternative stations of the two most recent FMs.
By doing in this way, even if the receiving units 2-1 and 2-2 receive traffic information (AM) broadcast in the tunnel, the reception status of the third receiving unit 2-3 Therefore, it is possible to determine the fluctuation of the received electric field intensity.

When it is determined from the reception status of the third reception unit 2-3 that the received electric field intensity has not changed suddenly (step ST7c; NO), the process returns to step ST1c.
On the other hand, when it is determined from the reception status of the third reception unit 2-3 that the received electric field strength has suddenly changed (step ST7c; YES), the process proceeds to step ST3c, and the alternative station search and the search are performed as in the first embodiment. The alternative station list is updated using this result.

  As described above, according to the third embodiment, the control unit 7 compares the results of a plurality of alternative station searches, and the received electric field strength of the broadcast wave satisfies a predetermined fluctuation condition within a predetermined time range. It is determined whether or not. By doing in this way, even if the receiving units 2-1 and 2-2 receive information broadcast in a specific area, the received electric field is determined from the reception status of the third receiving unit 2-3. It is possible to determine fluctuations in intensity. Thereby, the alternative station which can be received in the frequency band including the reception frequency selected by the user can be accurately presented.

Embodiment 4 FIG.
FIG. 9 is a block diagram showing a configuration of a broadcast receiving apparatus according to Embodiment 4 of the present invention. As shown in FIG. 9, the broadcast receiving device 1 </ b> C according to the fourth embodiment includes the USN detection unit 14 added to the configuration illustrated in FIG. 1 in the first embodiment, and the control unit 7 </ b> C instead of the control unit 7. Is provided.
The control unit 7C determines the reception field strength of the broadcast wave based on the reception field strength of the broadcast wave of the reception frequency selected by the user and the adjacent interference level received by the reception broadcast wave or the demodulation result of the reception signal. It is determined whether or not a predetermined variation condition is satisfied within the time range. The USN detector 14 is a detector that detects the adjacent disturbance level received by the received broadcast wave.
The details of the determination based on the received electric field strength of the broadcast wave of the reception frequency selected by the user and the adjacent interference level received by the received broadcast wave will be described below.

The control unit 7C periodically obtains the received electric field intensity detected by the signal meter 5a and the adjacent interference level detected by the USN detection unit 14, and receives the reception unit 2-1 and 2-2 based on these values. The reception status of the broadcast wave being received is judged as good or bad.
Here, the sudden change in the received electric field strength is determined by whether or not the received electric field strength of the broadcast wave satisfies a predetermined fluctuation condition within a predetermined time range.
For example, the reception electric field strength of the broadcast wave at time t is Lv (t) (dBuV), the threshold value indicating the upper limit of the reception electric field strength that cannot be received is Lev_Y, and the adjacent interference level received by the reception broadcast wave at time t Is USN (t) (%), a threshold value indicating the upper limit of the allowable adjacent disturbance level is USN_X, and a threshold value indicating the lower limit of the unacceptable adjacent disturbance level is USN_Y.
Lv (n) is an average value of the past n received electric field strengths detected by the signal meter 5a, and USN (n) is an average value of the past n times of adjacent interference levels detected by the USN detector 14. It is. In this case, it is determined that the reception state has deteriorated when all the variation conditions of the above equation (1) are satisfied or all the variation conditions of the following equation (3) are satisfied.
Lv (t1) ≦ Lev_Y
USN (t1) ≦ USN_X
Lv (n) ≧ Lev_Y
USN (n) ≧ USN_Y (3)

  However, in the above formula (3), it is preferable that the time interval for performing detection n times is equal to or shorter than the shortest search time among the alternative station search times in each frequency band. For example, when the FM alternative station search time is 15 seconds, the time interval for performing detection n times is set to 15 seconds or less. In this way, it is possible to immediately switch to the alternative station search in the frequency band including the frequency of the currently received broadcast without waiting for the alternative station search in any frequency band to end.

  Further, a sudden change in the received electric field strength may be determined using the error detection result of the RDS data by the RDS demodulator 6a. For example, the determination is performed by replacing USN (t1) and USN (n) in the above equation (3) with the error rate at time t1 and the average value of the error rate in n detections and comparing with the respective threshold values.

  As described above, according to the fourth embodiment, the control unit 7C allows the reception electric field strength of the broadcast wave of the reception frequency selected by the user and the adjacent interference level received by the reception broadcast wave or the demodulation of the reception signal. Based on the result, if it is determined that the received electric field strength of the broadcast wave satisfies a predetermined fluctuation condition within a predetermined time range and the reception condition of the broadcast wave has deteriorated, an alternative station search is performed in the frequency band including the received frequency. The third receiving unit 2-3 is controlled to perform the above. This also makes it possible to accurately present an alternative station that can be received in a frequency band including the reception frequency selected by the user.

In addition, although the said Embodiment 1-4 showed the case where a vehicle approached the tunnel, this invention is applicable also when a vehicle approachs the underground parking lot where an electromagnetic wave is interrupted | blocked. .
Moreover, in the said Embodiment 1-4, an electric field sudden change is detected too much, and there is a concern about the influence on another function by repeating a search. For example, there may be a case where there is no time to see traffic information. In this case, repeating the search by adding a time constraint may be restricted. For example, after searching once, a sudden change in electric field is not detected for a predetermined time (such as one minute).

  Also, the case of receiving a radio broadcast has been described as an example. However, in a broadcast receiving apparatus that receives digital broadcasts, TVs, satellite broadcasts, etc. in various countries, a user desires when the received electric field strength of the broadcast changes suddenly. Broadcast wave alternative stations can be searched with the highest priority.

  Further, even in radio broadcasting, it is possible not to search all of FM, MW, SW, and LW but only to a necessary band.

  In the second to fourth embodiments, the case where the reception units 2-1 and 2-2 receive phase diversity is shown. However, as shown in FIG. 4, the first reception unit transmits the broadcast of the frequency selected by the user. It may be a broadcast receiving device that receives only in 2-1.

  In the present invention, within the scope of the invention, any combination of each embodiment, any component of each embodiment can be modified, or any component can be omitted in each embodiment. .

  1, 1A-1C Broadcast receiving apparatus, 2a, 2b antenna, 2-1 first receiving unit, 2-2 second receiving unit, 2-3 third receiving unit, 3 PD control unit, 4a, 4b demodulation Unit, 5a, 5b signal meter, 6a, 6b RDS demodulation unit, 7, 7A-7C control unit, 8 amplifier unit, 9 speaker, 10 display unit, 10a display screen, 10b reception frequency, 10c alternative station list, 11 operation unit 12, 12A storage unit, 13 GPS reception unit, 13a GPS antenna, 14 USN detection unit.

Claims (5)

Provided with a plurality of receiving units, a broadcast wave of a selected reception frequency is received by some of the plurality of receiving units, and for each frequency band by the other receiving unit of the plurality of receiving units A broadcast receiving device that performs an alternative station search for checking whether there is a broadcast wave of an alternative station that can be received, and presents an alternative station in a frequency band including the reception frequency,
When it is determined that the reception electric field strength of the broadcast wave satisfies a predetermined fluctuation condition within a predetermined time range when the part of the reception units receives the broadcast wave of the reception frequency, the reception frequency is A broadcast receiving apparatus including a control unit that controls the other receiving unit so as to perform an alternative station search in a frequency band including the frequency band. A location information acquisition unit for acquiring location information;
A storage unit that stores the point where the alternative station search was performed as history information;
When the control unit determines from the position information that the device is in the area including the point of the history information, the control unit does not determine the variation in the received electric field strength of the broadcast wave, and substitutes the frequency band including the reception frequency. The broadcast receiving apparatus according to claim 1, wherein the other receiving unit is controlled to perform a station search.   The control unit compares the results of a plurality of alternative station searches to determine whether or not the received electric field strength of the broadcast wave satisfies a predetermined variation condition within a predetermined time range. The broadcast receiving apparatus described.   The control unit determines whether the reception electric field strength of the broadcast wave is within a predetermined time range based on the reception electric field strength of the broadcast wave of the reception frequency and the adjacent interference level received by the reception broadcast wave or the demodulation result of the reception signal. When the predetermined fluctuation condition is satisfied and it is determined that the reception state of the broadcast wave has deteriorated, the other receiving unit is controlled to perform an alternative station search in a frequency band including the reception frequency. The broadcast receiving apparatus according to claim 1. Provided with a plurality of receiving units, a broadcast wave of a selected reception frequency is received by some of the plurality of receiving units, and for each frequency band by the other receiving unit of the plurality of receiving units An alternative station search method of a broadcast receiving apparatus that performs an alternative station search for checking whether there is a broadcast wave of an alternative station that can be received, and presents an alternative station in a frequency band including the reception frequency,
A step of determining whether or not the received electric field intensity of the broadcast wave satisfies a predetermined fluctuation condition within a predetermined time range when the some receiving units are receiving the broadcast wave of the reception frequency; When,
When the control unit determines that the received electric field strength of the broadcast wave satisfies a predetermined variation condition within a predetermined time range, the other receiving unit performs a substitute station search in a frequency band including the reception frequency. And an alternative station search method comprising the steps of:

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