JP2019041245A - Digital broadcast receiver - Google Patents

Abstract

To provide a digital broadcast receiver capable of restraining deterioration of reception quality, by preventing troublesome changeover of broadcasting stations.SOLUTION: A terrestrial digital broadcast receiver 100 includes a search processing section 52 performing search operation for detecting a relay station when a determination is made that the reception state of broadcast wave of a first broadcast station under reception has became worse than the standard level, a reception state recovery determination section 53 for determining whether or not the reception state of broadcast wave of the first broadcast station is in restoration tendency in parallel with the search operation, and a changeover control section 54 for changing over to the relay station when the relay station is detected and the broadcast wave of the first broadcast station is not in restoration tendency, otherwise stopping changeover to the relay station.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a digital broadcast receiving apparatus that is mounted on a vehicle or the like and receives digital broadcasts such as video and audio.

  Conventionally, full-segment digital broadcasting is received by a 4-diver configuration using four tuner units, and reception of broadcast programs is continued using some tuner units when the reception state deteriorates, and the remaining tuner units are used. There is known a digital broadcast receiving apparatus that searches for a relay station and switches to a relay station that has a better reception state than a receiving broadcast station (see, for example, Patent Documents 1 and 2).

JP 2013-150056 A JP 2012-257011 A

  By the way, in the digital broadcast receiving devices disclosed in Patent Documents 1 and 2, when the scale of the relay station after switching is smaller than the broadcasting station before switching (when the transmission output is small), the vehicle is the relay station. If the vehicle passes the vicinity, the reception state of the relay station that is receiving abruptly deteriorates as the vehicle moves, and the search for the relay station may be required again in a short time. At that time, if the reception state of the original broadcast station is improved (for example, the reception state of the original broadcast station may be temporarily deteriorated due to the influence of multipath, etc.) Will be switched to the original broadcast station again. As described above, when switching to a small relay station, there is a case where switching of a broadcasting station frequently occurs, and there is a problem that reception quality is deteriorated.

  The present invention was created in view of the above points, and an object of the present invention is to provide a digital broadcast receiving apparatus that can prevent frequent switching of broadcast stations and suppress deterioration in reception quality. It is in.

  In order to solve the above-described problems, a digital broadcast receiving apparatus of the present invention is an in-vehicle broadcast receiving apparatus that is mounted on a vehicle and receives a broadcasted program, and receives a broadcast wave. A demodulation processing means for performing demodulation processing using a signal output from the broadcast wave receiving means, a video / audio reproduction means for generating video and audio corresponding to the received program based on the output of the demodulation processing means, and broadcasting The reception state determination unit that determines the reception state of the broadcast wave being received by the wave reception unit, and the reception state determination unit determines that the reception state is worse than the reference value. A search means for performing a search operation for detecting a second broadcast station different from the first broadcast station, and whether the broadcast wave reception state of the first broadcast station is in a recovery trend in parallel with the search operation by the search means Whether or not The reception state recovery determining means to be determined and the broadcast wave receiving means when the second broadcasting station is detected by the search means and the reception state recovery determining means does not determine that there is a recovery tendency. Is switched from the first broadcasting station to the second broadcasting station, and when the reception state recovery determining means determines that there is a recovery tendency, the first broadcast to be received by the broadcast wave receiving means Switching control means for stopping switching from the station to the second broadcasting station.

  Even when the reception state of the first broadcasting station being received deteriorates and a second broadcasting station different from the first broadcasting station is detected, the reception state of the first broadcasting station tends to recover. In this case, since the reception of the broadcast wave of the original first broadcasting station is continued without switching to the second broadcasting station, frequent switching of the broadcasting station can be prevented and accompanied by frequent switching A decrease in reception quality can be suppressed.

  Further, the broadcast wave receiving means described above has a plurality of tuner sections, a search operation by the search means is performed using a part of the plurality of tuner sections, and a search operation is performed using the rest of the plurality of tuner sections. It is desirable that a broadcast wave receiving operation corresponding to the first broadcasting station is performed in parallel with the first broadcasting station. By searching for a broadcasting station by background processing when the reception state deteriorates, it becomes possible to continue program reception of the receiving broadcasting station.

  Further, it is desirable that the broadcast wave reception operation corresponding to the first broadcast station before the start of the search operation described above is performed using a plurality of tuner units. By receiving broadcast waves by diversity reception using a plurality of tuner units, it is possible to improve reception quality during normal operation.

  Further, it is desirable that the search means described above detects a relay station or affiliated station corresponding to the first broadcast station as the second broadcast station. This makes it easy to switch to a relay station or affiliated station that is broadcasting the same program content when the reception state deteriorates.

  Further, it is desirable that the above-described reception state recovery determination unit determines whether or not there is a recovery tendency based on a result obtained by numerically expressing the reception state determined by the reception state determination unit at a predetermined time interval and polynomial approximation. As a result, it is possible to grasp how the reception state of the deteriorated first broadcasting station changes with time, and it is possible to accurately determine whether or not the reception state is in a recovery tendency. Become.

  In addition, the above-described reception state recovery determination means determines that the reception state tends to recover when the result of polynomial approximation indicates the tendency of the reception state to recover with the passage of time from the start of the search operation. It is desirable to do. Thereby, it is possible to confirm whether or not the deteriorated reception state is recovered during the search operation.

  Further, the polynomial approximation described above is a quadratic curve approximation, and it is preferable that the reception state recovery determination means determine the presence or absence of a recovery tendency based on the quadratic coefficient of the quadratic curve obtained by the quadratic curve approximation. . As a result, it becomes easy to grasp the tendency of the reception state to change and determine the presence or absence of the recovery tendency of the reception state.

  In addition, it is desirable that the above-described reception state recovery determination means determines that there is a recovery tendency when the reception state of the broadcast wave of the first broadcasting station is better than when the search operation starts. Thereby, it is possible to easily confirm that the reception state is recovered.

  Further, the switching control means described above is configured such that when the second broadcast station is detected by the search means, the broadcast wave reception state of the second broadcast station is more than the broadcast wave reception state of the first broadcast station. The reception target by the broadcast wave receiving means is switched from the first broadcasting station to the second broadcasting station when the reception state recovery determining means does not determine that the reception state recovery determination means is in a recovery tendency. Is desirable. As a result, it is possible to determine whether or not the reception state has been restored after waiting for switching according to the search operation, so that the determination accuracy can be improved.

  Further, the switching control means described above stores the second broadcasting station whose switching has been canceled, and when the next reception state determination means determines that the reception state is worse than the reference value, the search is performed. Prior to the operation, it is desirable to switch the reception target by the broadcast wave receiving means to the stored second broadcast station. As a result, when the switching is temporarily stopped and the original broadcast station continues to be received, but the reception state deteriorates again, it is possible to quickly switch to the previously detected broadcast station. The time required for the process can be shortened.

It is a figure which shows the structure of the terrestrial digital broadcast receiver of one Embodiment. It is a flowchart which shows the operation | movement procedure which searches and switches a relay station, when the receiving state of the broadcast wave currently receiving is deteriorated. It is a figure which shows the specific example of a secondary approximation type | formula and the presence determination of reception status recovery. It is a flowchart which shows the operation | movement procedure of the modification which searches and switches a relay station, when the reception state of the broadcast wave currently received is deteriorated.

  Hereinafter, a digital terrestrial broadcast receiver according to an embodiment to which the present invention is applied will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a terrestrial digital broadcast receiver according to an embodiment. As shown in FIG. 1, the terrestrial digital broadcast receiver 100 of this embodiment is mounted on a vehicle, and includes four tuner units 10, 12, 14, 16, and OFDM (Orthogonal Frequency Division Multiplex) demodulator units 30, 32. MPEG decoder 40, digital-analog converter (D / A) 42, speaker 44, display processing unit 46, display device 48, and control unit 50.

  Each of the tuner units 10, 12, 14, and 16 receives a broadcast wave having a reception frequency corresponding to a designated broadcast station via an antenna. Each of the OFDM demodulation units 30 and 32 performs OFDM demodulation processing on broadcast signals (IF signals) input from a plurality of tuner units, and outputs a TS (transport stream) signal. In the present embodiment, a combined diversity configuration is employed in which broadcast signals input from a plurality of tuner units are used, and the phases of these broadcast signals are adjusted and then combined and received. As the number of tuner units used increases, C / N can be improved.

  In this embodiment, when the broadcast signal reception state is good, four synthesis divers that perform OFDM demodulation processing by synthesizing four IF signals output from the four tuner units 10, 12, 14, and 16 These operations are performed by the OFDM demodulator 30. On the other hand, when the reception state of the broadcast signal deteriorates, one OFDM demodulator 30 performs an operation of a two-combining diver that performs OFDM demodulation processing by combining two IF signals output from the two tuner units 10 and 12. At the same time, the other OFDM demodulator 32 performs the operation of a two-synthesis diver that synthesizes two IF signals output from the other two tuner units 14 and 16 and performs OFDM demodulation processing. When performing the above-described four-combining diver operation, the output signal of the other OFDM demodulator 32 is input to one OFDM demodulator 30, and this OFDM demodulator 30 combines IF signals and performs OFDM demodulation processing. Is done.

  The MPEG decoder 40 decodes the received program audio and video MPEG signals included in the TS signals output from the OFDM demodulation units 30 and 32, and outputs audio data and video data. In practice, the TS signals output from the OFDM demodulating units 30 and 32 are input to the demultiplexer, and the audio and video MPEG signals corresponding to the program that the user desires to watch are separated. The program receiving operation itself is the same as that of the conventional method, and only a schematic configuration is shown in FIG.

  The digital-analog converter 42 converts the audio data output from the MPEG decoder 40 into an analog audio signal and outputs it from the speaker 44. The display processing unit 46 converts the video data output from the MPEG decoder 40 into a video signal in a format suitable for display (for example, NTSC format) and displays the video signal on the display device 48.

  The controller 50 controls the overall operation of the terrestrial digital broadcast receiver 100 including a program receiving operation and a search operation for relay stations and affiliated stations by executing a predetermined operation program using a CPU, ROM, RAM, and the like. . For this purpose, the control unit 50 includes a reception state determination unit 51, a search processing unit 52, a reception state recovery determination unit 53, and a switching control unit 54.

  The reception state determination unit 51 determines the reception state of the broadcast wave using all or a part of the four tuner units 10 to 16. Specifically, the reception state determination unit 51 uses the operation of determining the reception state of the broadcast wave during the operation of the 4-synthesis diver using the four tuner units 10 to 16 and the two tuner units 10 and 12. The broadcast wave reception state during the operation of the two-combination diver and the operation for obtaining the broadcast wave reception state during the operation of the two-combination diver using the two tuner units 14 and 16 are selectively performed. Further, for example, C / N is acquired as the reception state, but other characteristic values such as BER may be acquired.

  When the reception state determination unit 51 determines that the reception state of the broadcast wave of the currently receiving broadcast station (first broadcast station) is worse than the reference value, the search processing unit 52 A search operation for detecting a second broadcast station different from the broadcast station is performed. Specifically, the search processing unit 52 examines the program content corresponding to the broadcast wave (viewing channel) of the first broadcasting station currently being received, and at the same time is a tuner that is the target of demodulation processing by the OFDM demodulation unit 32. A frequency switching instruction is sent to the units 14 and 16, and the second broadcast is broadcast to a relay station or affiliated station that broadcasts another program having the same content as the program of the first broadcast station that the user is viewing. A search operation to detect as a station is performed.

  In parallel with the search operation by the search processing unit 52, the reception state recovery determination unit 53 determines whether or not the reception state of the broadcast wave of the receiving broadcast station (first broadcast station) is in a recovery tendency. Specifically, the reception state recovery determination unit 53 determines whether or not there is a recovery tendency based on a result obtained by numerically expressing the reception state (C / N) determined by the reception state determination unit 51 at a predetermined time interval and polynomial approximation. judge. More specifically, the reception state recovery determination unit 53 indicates a tendency that the reception state recovers as time elapses when the search processing unit 52 starts the search operation, as a result of the above polynomial approximation. It is determined that the person is in a recovery trend. In particular, the polynomial approximation described above is preferably a quadratic curve approximation. In this case, the reception state recovery determination unit 53 recovers based on the quadratic coefficient of the quadratic curve obtained by the quadratic curve approximation. Determine whether there is a trend.

  The switching control unit 54 is when the second broadcasting station is detected by the search processing unit 52 and the reception state recovery determining unit 53 does not determine that the first broadcasting station is in a recovery tendency. In addition, processing for switching the reception target from the first broadcasting station to the second broadcasting station by the tuner units 10 to 16 is performed, and the reception state recovery determination unit 53 determines that the first broadcasting station is in a recovery tendency. When it is interrupted, processing for canceling the switching from the first broadcasting station to be received by the tuner units 10 to 16 to the second broadcasting station is performed.

  The tuner units 10, 12, 14, and 16 described above are broadcast wave receiving means, the OFDM demodulating units 30 and 32 are demodulation processing means, the MPEG decoder 40 is video / audio reproduction means, and the reception state determination unit 51 is a reception state determination. The search processing unit 52 corresponds to the search unit, the reception state recovery determination unit 53 corresponds to the reception state recovery determination unit, and the switching control unit 54 corresponds to the switching control unit.

  The terrestrial digital broadcast receiver 100 of the present embodiment has such a configuration, and next, the operation when the reception state of the broadcast wave of the broadcast station (first broadcast station) viewing the program deteriorates Will be described.

  In terrestrial digital broadcasting, broadcast waves having a structure compliant with the MPEG2-TS (Transport Stream) standard are distributed. MPEG2-TS has a TS header part and a payload part (data body). The TS header part and the payload part constitute a 188-byte transport packet. The data transmitted by the MPEG2-TS includes PAT (Program Association Table), PMT, NIT, BIT, and the like.

  PAT: PID (Packet Identification, packet identification information) of a transport packet transmitting a table (PMT) describing the program configuration is described for each program (program) number. The PID of the PAT itself has a fixed value (0x0000). This PAT is received once within a predetermined time.

  PMT: The transport packet PID list and associated information (service identification, etc.) are described in the payload portion of this transport packet in which individual streams such as video and audio constituting one program are transmitted. Yes.

  NIT: The network identification of the broadcasting station is described in the payload portion of this transport packet.

  BIT: affiliated station information is included in the payload portion of this transport packet. The PID of BIT has a fixed value (0x0024). The extended broadcaster descriptor of this BIT includes affiliation_id (affiliation station identification).

  FIG. 2 is a flowchart showing an operation procedure for searching for and switching a relay station when the reception state of a currently received broadcast wave deteriorates.

  Normally, diversity reception of a four-diversity configuration using four tuner units 10 to 16 is performed on a broadcast wave of a broadcasting station (first broadcasting station) designated by a user, and a received program of a full segment digital broadcasting is received. The sound is output from the speaker 44 and the video is displayed on the screen of the display device 48 (step 100).

  Next, the reception state determination unit 51 determines whether or not the reception state in diversity reception with a 4-diversity configuration has deteriorated (step 102). This determination is performed by comparing the C / N of the broadcast wave being received with a reference value (for example, 17 dB). If C / N is equal to or greater than the reference value and the reception state is good, a negative determination is made in the determination of step 102. In this case, returning to step 100, the program receiving operation is repeated.

  If C / N is lower than the reference value and the reception state deteriorates, an affirmative determination is made in the determination of step 102. Next, the switching control unit 54 switches the target of demodulation processing by the OFDM demodulating unit 30 from the four tuner units 10 to 16 to the two tuner units 10 and 12, and broadcast waves of the first broadcasting station that is watching the program. Is continued (step 104).

  Further, the search processing unit 52 starts the search operation of the relay station in the background to check the presence or absence of the relay station based on the demodulation processing by the OFDM demodulation unit 32 while switching the reception frequencies of the tuner units 14 and 16 in a predetermined order. (Step 106). For example, the frequency of the relay station (relay station frequency) can be known based on NIT or the like included in the currently received broadcast wave, and the relay station frequency is selected in order along the search direction. The program reception in step 104 and the relay station search operation in step 106 may be performed after switching from full segment digital broadcast reception to one segment digital broadcast reception.

  Next, the reception state recovery determination unit 53 acquires the C / N of the channel being viewed (the broadcast wave of the first broadcast station) and stores it in an internal register (not shown) (step 108). The location where the acquired C / N is stored is not limited to the internal register, but may be a semiconductor memory or the like. Moreover, it is desirable to acquire C / N stored in the internal register at regular time intervals.

  Next, the reception state recovery determination unit 53 reads a plurality of C / Ns stored in the internal register, and performs a second-order polynomial approximation on the plurality of C / Ns (step 110).

  Next, the search processing unit 52 determines whether or not a relay station has been detected (step 112). If no relay station is detected, a negative determination is made, and the search processing unit 52 determines whether or not the search operation for detecting the relay station has made a round for the received frequency band (step 114). If the circuit does not go round, a negative determination is made, the process returns to step 108, and the C / N acquisition and storage operations are repeated. Further, when the search operation makes a round for the reception frequency band, an affirmative determination is made in the determination of step 114. Thereafter, returning to step 100, the program reception of the broadcasting station being viewed by the 4-diver reception is continued.

  If a relay station is detected by the search operation, an affirmative determination is made in the determination of step 112. Next, the switching control unit 54 determines whether or not the detected C / N of the relay station is better than the C / N of the broadcasting station being viewed by two-diver reception using the tuners 10 and 12 (Step S1). 116). If the C / N of the relay station is better, a positive determination is made. Next, the reception state recovery determination unit 53 determines whether or not the second order coefficient of the polynomial (second order approximate expression) obtained by the calculation in step 110 is greater than or equal to a threshold value (step 118). The case where the secondary coefficient is equal to or greater than the threshold value is a case where the C / N of the broadcasting station being viewed is in a recovery tendency (a specific example will be described later), and an affirmative determination is made in the determination of step 118 Is done. In such a case, the switching control unit 54 stops switching to a relay station with a good detected C / N (step 120). Thereafter, returning to step 100, the program reception of the broadcasting station being viewed by the 4-diver reception is continued.

  If the secondary coefficient of the quadratic approximate expression is smaller than the threshold value (when the C / N of the broadcasting station being viewed does not tend to recover), a negative determination is made in the determination at step 118. In such a case, the switching control unit 54 sends an instruction to the tuner units 10 to 16 to switch the broadcast station to be viewed to the detected relay station (step 122). Thereafter, returning to step 100, the program reception of the broadcasting station being viewed by the 4-diver reception is continued.

FIG. 3 is a diagram illustrating a specific example of a quadratic approximation formula and determination of presence / absence of reception state recovery. In FIG. 3, the horizontal axis represents elapsed time, and the vertical axis represents C / N. When the C / N of the broadcasting station (first broadcasting station) that is being viewed by 4-diver reception becomes worse than the reference value (a), the program viewing by 2-diver reception using the tuner units 10 and 12 is continued. In (b), the search operation of the relay station by 2-diver reception using the tuner units 14 and 16 is started. During this search operation, the C / N of the broadcast wave of the broadcasting station being viewed is acquired at predetermined time intervals, and second order approximation is performed. Then, when the relay station is detected (c), it is confirmed that the C / N of this relay station is better than the C / N (d) of the broadcasting station currently being viewed. The relay station becomes the broadcasting station (second broadcasting station) to be switched, but at the time, the second approximation formula (y = 0.09x ² -1.02x + 11.17) obtained by the second order approximation is used. When the second order coefficient (0.09) is equal to or greater than a predetermined threshold value (for example, 0) and C / N tends to recover, that is, this quadratic approximate expression has a downwardly convex shape, and thereafter C / N Is expected to increase, the switching to the relay station is stopped.

  As described above, in the terrestrial digital broadcast receiver 100 of the present embodiment, the reception state of the first broadcast station that is receiving (viewing) deteriorates, and the second broadcast station that is different from the first broadcast station. Even if the first broadcast station reception state is in a recovery trend, the reception of the broadcast wave of the original first broadcast station is continued without switching to the second broadcast station. Therefore, frequent switching of broadcasting stations can be prevented, and deterioration in reception quality due to frequent switching can be suppressed.

  Also, the search operation is performed using the two tuner units 10 and 12 among the four tuner units 10 to 16, and the reception operation of the first broadcasting station is performed in parallel with the search operation using the remaining tuner units 14 and 16. When the broadcast wave reception state of the first broadcast station being viewed is deteriorated, the relay station is searched by background processing, so that the program reception of the first broadcast station can be continued.

  In addition, since the reception operation of the broadcast wave corresponding to the first broadcasting station before the start of the search operation is performed by a four-diver configuration using the four tuner units 10 to 16, the reception quality of the program during the normal operation is improved. Improvement is possible.

  Further, by detecting the relay station corresponding to the first broadcast station in the search operation, it is possible to continue viewing the same content even when the broadcast station is switched when the reception state deteriorates.

  Further, for the first broadcasting station receiving in parallel with the search operation, the reception state is deteriorated by determining the presence or absence of recovery tendency based on the result of polynomial approximation by numerically expressing the reception state at a predetermined time interval. It is possible to grasp how the reception state of one broadcasting station is changing over time, and it is possible to accurately determine whether or not the reception state is in a recovery tendency. In particular, when the result of approximation of the polynomial shows the tendency of the reception state to recover with the passage of time with respect to the start of the search operation, it is determined that there is a recovery tendency, which worsened It is possible to confirm whether or not the reception state has been recovered during the search operation.

  The polynomial approximation used is a quadratic curve approximation, and the presence or absence of a recovery tendency is determined based on the quadratic coefficient of the quadratic curve obtained by the quadratic curve approximation. Specifically, it is determined that there is a recovery tendency when the value of the secondary coefficient is equal to or greater than a predetermined threshold (for example, 0). As a result, it becomes easy to grasp the tendency of the reception state to change and determine the presence or absence of the recovery tendency of the reception state.

  Further, when the second broadcast station is detected by the search operation, the C / N of the broadcast wave of the relay station is better than the C / N of the broadcast wave of the first broadcast station, and When the determination that the C / N of the broadcast wave of the first broadcasting station is in a recovery tendency is not made (when there is no recovery tendency), switching to the relay station is performed. As a result, it is possible to determine whether or not C / N has been recovered after waiting for switching according to the search operation, so that it is possible to increase the determination accuracy of this recovery tendency.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention. For example, in the above-described embodiment, in parallel with the search operation, the C / N of the broadcast wave of the first broadcast station being viewed is second-order approximated, and the reception state of this broadcast wave is based on the secondary coefficient. It is determined whether or not there is a recovery tendency. However, in combination with this determination operation (first determination method) or instead of this determination operation, at the time when the relay station is detected, the first broadcasting station When the reception state of the broadcast wave is better than that at the start of the search operation, a determination (second determination method) that the reception state of the broadcast wave of the first broadcasting station is in a recovery tendency may be performed. . By using a combination of the first determination method and the second determination method, it is possible to know the recovery tendency of the reception state more accurately. Further, by using the second method alone, it is possible to easily confirm that the reception state has been recovered.

  In the above-described embodiment, even when the relay station is detected by the search operation, if the broadcast wave reception state of the first broadcasting station being viewed is in a recovery tendency, Switching is canceled, but next, when the reception state of the broadcast wave of the first broadcasting station that is being watched deteriorates again, switching is preferentially performed to the relay station that canceled the previous switching without performing a search operation. You may do it.

  FIG. 4 is a flowchart showing an operation procedure of a modified example in which the relay station is searched and switched when the reception state of the currently received broadcast wave deteriorates. The operation procedure shown in FIG. 4 is different from the operation procedure shown in FIG. 2 in that the operation of Step 103 is added between Step 102 and Step 104, and the operation of Step 119 is added after Step 118. Is different. In the following, description will be given focusing on these added steps 103 and 119.

  When the reception state of the broadcast wave of the first broadcasting station being viewed is in a recovery trend in parallel with the search operation and an affirmative determination is made in the determination in step 118, the switching control unit 54 cancels the switching. Is stored (step 119). The operation in step 119 may be performed after the operation in step 120 (stopping switching to the relay station).

  If the reception state of the broadcast wave of the first broadcasting station being viewed deteriorates and an affirmative determination is made in step 102, the switching control unit 54 next determines whether there is a stored relay station. Is determined (step 103). If the relay station is not stored, a negative determination is made, the process proceeds to step 104, and thereafter, a search operation for detecting the relay station and the like are performed. If the relay station has already been stored in step 119, an affirmative determination is made in step 103. In this case, the operation proceeds to the operation of step 122, and switching to the stored relay station is performed.

  As a result, when the switching is temporarily stopped and the original broadcast station continues to be received, but the reception state deteriorates again, it is possible to quickly switch to the previously detected broadcast station. The time required for the process can be shortened.

  In the above-described embodiment, the target of the broadcast station detected by the search operation is the relay station. However, both the relay station and the affiliated station may be targeted.

  As described above, according to the present invention, even when the reception state of the first broadcasting station being received is deteriorated and a second broadcasting station different from the first broadcasting station is detected, When the reception state of the first broadcasting station is in a recovery trend, since the reception of the broadcast wave of the original first broadcasting station is continued without switching to the second broadcasting station, frequent switching of the broadcasting stations is performed. It is possible to prevent the degradation of reception quality due to frequent switching.

100 Digital Terrestrial Broadcasting Receiver 10, 12, 14, 16 Tuner Unit 30, 32 OFDM Demodulator 40 MPEG Decoder 42 Digital-Analog Converter (D / A)
44 Speaker 46 Display Processing Unit 48 Display Device 50 Control Unit 51 Reception State Determination Unit 52 Search Processing Unit 53 Reception State Recovery Determination Unit 54 Switching Control Unit

Claims (10)

An in-vehicle broadcast receiving device that is installed in a vehicle and receives a broadcasted program,
Broadcast wave receiving means for receiving broadcast waves;
Demodulation processing means for performing demodulation processing using a signal output from the broadcast wave receiving means;
Video / audio reproduction means for generating video and audio corresponding to the received program based on the output of the demodulation processing means;
Reception state determination means for determining the reception state of the broadcast wave being received by the broadcast wave reception means;
A search for performing a search operation for detecting a second broadcast station different from the first broadcast station that is receiving the broadcast wave when the reception state determination means determines that the reception state is worse than a reference value. Means,
In parallel with the search operation by the search means, reception state recovery determination means for determining whether or not the reception state of the broadcast wave of the first broadcasting station has a recovery tendency;
When the second broadcasting station is detected by the search means, and when the reception state recovery determination means does not determine that there is a recovery tendency, the reception target by the broadcast wave reception means is The first broadcast station is switched to the second broadcast station, and when the reception state recovery determination means determines that there is a recovery tendency, the first broadcast to be received by the broadcast wave reception means Switching control means for canceling switching from the station to the second broadcasting station;
A digital broadcast receiving apparatus comprising: The broadcast wave receiving means has a plurality of tuner units,
A search operation by the search means is performed using a part of the plurality of tuner units, and reception of broadcast waves corresponding to the first broadcast station in parallel with the search operation using the rest of the plurality of tuner units. 2. The digital broadcast receiving apparatus according to claim 1, wherein an operation is performed.   3. The digital broadcast receiving apparatus according to claim 2, wherein a broadcast wave reception operation corresponding to the first broadcast station before the search operation is started is performed using the plurality of tuner units.   The digital broadcast reception according to any one of claims 1 to 3, wherein the search means detects a relay station or affiliated station corresponding to the first broadcast station as the second broadcast station. apparatus.   The reception state recovery determination unit determines whether or not the recovery tendency exists based on a result obtained by numerically expressing the reception state determined by the reception state determination unit at a predetermined time interval and polynomial approximation. The digital broadcast receiving apparatus as described in any one of 1-4.   The reception state recovery determination means determines that the reception state tends to recover when the result of the polynomial approximation indicates a tendency that the reception state recovers with time from the start of the search operation. The digital broadcast receiving apparatus according to claim 5, wherein: The polynomial approximation is a quadratic curve approximation,
The digital broadcast according to claim 5 or 6, wherein the reception state recovery determination means determines the presence or absence of the recovery tendency based on a quadratic coefficient of a quadratic curve obtained by the quadratic curve approximation. Receiver device.   The reception state recovery determination unit determines that the reception state of the broadcast wave of the first broadcasting station is in a recovery tendency when the reception state of the broadcast wave is better than that at the start of the search operation. Item 8. The digital broadcast receiver according to any one of Items 1 to 7.   When the second broadcast station is detected by the search means, the switching control means has a reception state of the broadcast wave of the second broadcast station rather than a reception state of the broadcast wave of the first broadcast station. Is better, and when the reception state recovery determination means does not determine that there is a recovery tendency, the reception target by the broadcast wave reception means is changed from the first broadcast station to the second broadcast station. The digital broadcast receiver according to claim 1, wherein the digital broadcast receiver is switched to a broadcast station.   The switching control means stores the second broadcasting station for which switching has been canceled, and the next time the reception status determining means determines that the reception status is worse than a reference value, the search The digital broadcast receiving apparatus according to any one of claims 1 to 9, wherein, prior to operation, the reception target by the broadcast wave receiving means is switched to the second broadcast station that has been stored. .

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