JP2016092438A - Mobile digital broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a disadvantage that when a mobile moves an area where a strong hierarchy layer and a weak hierarchy layer are switched frequently, the video and audio outputs of a broadcast signal of the strong hierarchy layer and weak hierarchy layer are switched and the interruption frequency increases.SOLUTION: In step S25, a control unit 9 sets a switching area. More specifically, when moving the same route to the third time, it is stored as shown on fig. 3(a) in the first time movement, and stored as shown on fig. 3(b) in the second time movement. They are combined, and an area where the information E1, E2 are continuous is set as a changeover area N2, as shown on fig. 2(c). Since changeover from weak hierarchy to strong hierarchy is carried out at a changeover detection point a3, and subsequent changeover to weak hierarchy in the changeover area N2 is prohibited at step S34, strong hierarchy continues in the changeover area N2.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a mobile digital broadcast receiving apparatus that is mounted on a mobile body such as a vehicle and receives terrestrial digital broadcasts.

  As an example of the segment structure of terrestrial digital broadcasting, in the segment structure of OFDM (Orthogonal Frequency Division Multiplexing), one segment out of 13 segments is a segment that performs digital broadcasting for mobile and mobile objects. Yes. For example, QPSK (Quadrature Phase Shift Keying), which is strong against noise and multipath, is applied to this one segment as a modulation method, and digital broadcasting for portable / mobile objects composed of this one segment. A layer for performing (so-called one-segment broadcasting) is called a strong layer. In this strong one-segment broadcasting, simple video broadcasting can be viewed.

  On the other hand, the other 12 segments are segments for performing fixed digital broadcasting. For these 12 segments, for example, 64QAM (Quadrature Amplitude Modulation), which is weak against noise and multipath and has a high bit rate, is applied as a modulation method. Digital broadcasting for fixed use composed of these 12 segments is used. A layer for performing (so-called full segment broadcasting) is called a weak layer. In this weak-segment full-segment broadcasting, HDTV (High Definition TeleVision) broadcasting and SDTV (Standard Definition TeleVision) broadcasting can be viewed.

  In such a terrestrial digital broadcast, if the broadcast contents of the fixed digital broadcast and the portable / mobile digital broadcast are the same, such simultaneous broadcast is referred to as simultaneous broadcast. In simulcast, the same broadcast contents (programs and services) can be simultaneously provided by both the strong and weak layers. Such simulcasting is also applied to a digital broadcast receiving apparatus mounted on a vehicle or the like.

  In this type of digital broadcast receiver, a signal quality value and a threshold value are compared at predetermined intervals, and a video signal in a weak layer is selected under a predetermined condition by comparing the signal quality value and the threshold value. Switch to the strong hierarchy video signal, and if the strong hierarchy video signal is selected, switch to the weak hierarchy video signal to switch the broadcast transmitted by the weak hierarchy to the vehicle. It has been proposed to receive as much as possible while traveling and reduce frequent layer switching (Patent Document 1).

JP 2008-42229 A

  In the apparatus described in Patent Document 1 described above, when a moving body moves in an area where the strong hierarchy and the weak hierarchy are frequently switched, the video / audio output of the broadcast signal between the strong hierarchy and the weak hierarchy is switched. There was a drawback that the frequency of interruptions increased.

  The mobile digital broadcast receiver according to claim 1 is mounted on a mobile body, and receives and switches between a weak layer and a strong layer of digital broadcasting based on a predetermined switching condition while the mobile body is moving. When the switching condition is satisfied, the storage unit that stores information of the switching detection point that satisfies the switching condition, the area setting unit that sets the switching area based on the information of the switching detection point stored in the storage unit, Even so, if the position of the moving body is within the switching area, a control unit is provided that prohibits the receiving unit from switching from the strong hierarchy to the weak hierarchy.

  According to the present invention, even when a moving body moves in an area where the strong hierarchy and the weak hierarchy are frequently switched, the frequency at which the video / audio output of the broadcast signal is switched between the strong hierarchy and the weak hierarchy is reduced. Can do.

It is a block diagram of a mobile digital broadcast receiver. It is a figure which shows the positional information on a switching detection point. It is a figure which shows the memory | storage state of a memory | storage part. It is a flowchart explaining operation | movement of a mobile digital broadcast receiver.

  FIG. 1 is a block diagram showing a mobile digital broadcast receiving apparatus according to an embodiment of the present invention. 1 is an antenna unit, 2 is a channel selection unit, 3 is a demodulation unit, 4 is a demultiplexing unit, 5 is a weak layer decoding unit, 6 is a strong layer decoding unit, 7 is a switching unit, 8 is a video display unit, and 9 is a control unit Reference numeral 10 denotes a GPS (Global Positioning System) receiver, and 11 denotes a storage unit. The receiving unit of the mobile digital broadcast receiving apparatus includes an antenna unit 1, a channel selection unit 2, a demodulation unit 3, a demultiplexing unit 4, a weak layer decoding unit 5, a strong layer decoding unit 6, and a switching unit 7.

  In FIG. 1, an antenna unit 1 receives a broadcast wave and supplies it to a channel selection unit 2. The channel selection unit 2 selects a digital broadcast signal of a desired channel from the supplied broadcast radio wave and supplies it to the demodulation unit 3. The demodulator 3 performs demodulation and error correction processing on the supplied digital broadcast signal and supplies it to the demultiplexer 4 as a transport stream (Transport Stream, hereinafter referred to as TS) signal. A value relating to signal quality (hereinafter referred to as a signal quality value) is detected and supplied to the control unit 9.

  This signal quality value includes the synchronization state with the received digital broadcasting signal, carrier power to noise ratio (CNR), bit error rate in error correction processing, AGC control voltage, modulation error ratio (MER). (Modulation Error Ratio)). Here, it is assumed that the reception state is good when the signal quality value is large, and the reception state is bad when the signal quality value is small.

  The demultiplexing unit 4 separates the TS signal supplied from the demodulation unit 3 into a weak layer TS signal and a strong layer TS signal. The separated weak hierarchy TS signal is supplied to the weak hierarchy decoding unit 5 and decoded into a weak hierarchy video signal. On the other hand, the separated strong layer TS signal is supplied to the strong layer decoding unit 6 and decoded into a strong layer video signal. Subsequently, the video signal of the weak hierarchy and the video signal of the strong hierarchy are supplied to the switching unit 7, and one of the video signals is selected and supplied to the video display unit 8. The video display unit 8 outputs video and audio based on the video signal. The selection of the video signal in the switching unit 7 is controlled by the control unit 9. The control unit 9 determines a reception hierarchy to be selected based on the signal quality value supplied from the demodulation unit 3, controls the switching unit 7 with a switching signal corresponding to the determination result, and also within a switching area described later. For example, the switching unit 7 is controlled so as to prohibit switching from the strong hierarchy to the weak hierarchy.

  Here, the weak layer and the strong layer are stipulated in the terrestrial digital broadcast operation regulations (ARIB TR-B14), and can transmit a relatively high-quality video signal, but the layer that is relatively vulnerable to interference in the transmission path. It is called a weak layer, and a video signal with a relatively low image quality can be transmitted, but a layer that is relatively strong against interference in the transmission path is called a strong layer. Here, it is assumed that programs having the same content are broadcast on the weak and strong layers.

  When the mobile digital broadcast receiver is mounted on a vehicle for in-vehicle use, the GPS receiver 10 passes the position information of the travel route traveled by the vehicle to the control unit 9. Further, when the mobile digital broadcast receiving apparatus is a portable device and the user carries it and gets on a transportation system such as a train or a vehicle, the position information of the travel route traveled by the transportation system is transferred to the control unit 9. . The storage unit 11 stores position information acquired from the GPS receiver 10 and stores area information described later.

  2 (a) to 2 (d) show switching detection points between a weak hierarchy and a strong hierarchy when a mobile body equipped with a mobile digital broadcast receiving apparatus moves from the left to the right in the figure. FIG. In addition, although the movement path | route is shown with the straight line in order to simplify description, it should just follow a movement path | route, such as a curve. In each figure, double circles indicate switching detection points from the weak hierarchy to the strong hierarchy, and circles indicate switching detection points from the strong hierarchy to the weak hierarchy. The detection of switching from the weak layer to the strong layer is detected based on the signal quality value supplied from the demodulation unit 3 to the control unit 9 when the reception state of the weak layer is bad. The switching detection is detected when the reception status of the strong hierarchy is good for a predetermined time. The alphabetic character code in the figure indicates the position information of each switching detection point. The position information includes latitude and longitude acquired from the GPS receiver 10. The areas indicated by the broken lines are the switching areas N1 to N3. If switching from the strong hierarchy to the weak hierarchy is detected within this switching area, actual switching is prohibited.

  FIGS. 2A to 2D show cases where the same movement route is moved from the first time to the fourth time, respectively. Although details will be described later, when switching detection is performed twice or more within a predetermined distance L at each switching detection point between the weak hierarchy and the strong hierarchy, the same switching areas N1 to N3 are set.

  FIGS. 3A to 3D show information stored in the storage unit 11 when moving along the movement route as shown in FIGS. 2A to 2D, respectively. The route information 31 is information indicating the name of the route and whether it is up or down, and the number of movements. Information indicating the name of the route and whether it is up or down is read out and stored with reference to a map database not shown. The number of times of movement is the number of times of movement on the same route. The reason for distinguishing between uplink and downlink is that, for example, when the mobile digital broadcast receiver is mounted on a vehicle for in-vehicle use, the reception state differs depending on the mounting position of the antenna unit 1 and the orientation of the vehicle. . The position information 32 is information such as latitude and longitude acquired from the GPS receiver 10 at the switching detection point. The hierarchy information 33 stores S for a switching detection point from the weak hierarchy to the strong hierarchy and Q for a switching detection point from the strong hierarchy to the weak hierarchy. The area information 34 stores information E1 to E4 indicating switching areas. In association with the position information 32, hierarchical information 33 and area information 34 are stored.

  FIG. 4 is a flowchart showing the operation of the mobile digital broadcast receiver. The program shown in this flowchart is stored in a memory (not shown) in the control unit 9, and each process of the program is executed by the control unit 9.

The operation of the present embodiment will be described below with reference to FIG. The mobile digital broadcast receiving apparatus starts the processing shown in FIG. 4 in a power-on state.
(When moving the same route for the first time)
In the case of moving the same route for the first time, in step S10, the control unit 9 determines whether the route is moving for the first time. Specifically, the route information 31 in the storage unit 11 is referred to, and if the currently moving route is not stored, it is determined that the route is the first route to be moved. In this case, since the route travels for the first time, an affirmative determination is made in step S10 and the process proceeds to step S11. If the route travels after the second time, the process proceeds to step S23.

  In step S <b> 11, the control unit 9 determines whether the currently moving route is stored in the storage unit 11 as the route information 31. If not stored, the process proceeds to step S12. If stored, the process proceeds to step S13. In the case of moving the same route for the first time, the processing of the following step S12 has not been executed, so in step S11, it is determined that the currently moving route is not stored as the route information 31. Proceed to step S12.

  In step S <b> 12, the control unit 9 writes the currently moving route in the storage unit 11 as route information 31. The route information 31 includes the name of the route, information indicating whether it is up or down, and the number of movements. In this case, since the same route is moved for the first time, 1 is stored as the number of times of movement.

  Thereafter, the process proceeds to step S13, and the control unit 9 demodulates the broadcast signal received by the antenna unit 1 by the demodulation unit 3 to perform reception, and then proceeds to step S14.

  In step S14, the control unit 9 determines whether or not the reception state of the mobile digital broadcast receiving apparatus is reception by a weak hierarchy. Specifically, if the hierarchy of the video signal selected by the switching unit 7 is a weak hierarchy, the reception state is determined to be a weak hierarchy and the process proceeds to step S15. Otherwise, the process proceeds to step S20. In this case, if it is before reaching the switching detection point a1 in FIG. 2A, an affirmative determination is made in step S14 and the process proceeds to step S15. In step S15, it is determined whether the signal quality value is within a predetermined quality. If it is within the predetermined quality, reception by the weak hierarchy is continued even during movement. The determination in step S15 is continuously performed, and when the signal quality value is not within the predetermined quality, the process proceeds to step S16. In this case, an affirmative determination is made in step S15 until the switching detection point a1 is passed, and a negative determination is made in step S15 when the switching detection point a1 is passed, that is, the first switching condition is satisfied, and the process proceeds to step S16. move on.

  In step S16, the control unit 9 switches the hierarchy of the broadcast signal received by the mobile digital broadcast receiver from the weak hierarchy to the strong hierarchy. Specifically, the switching unit 7 selects the video signal of the strong hierarchy and switches the hierarchy of the video signal output to the video display unit 8 from the weak hierarchy to the strong hierarchy. Thereafter, the process proceeds to step S17.

  In step S <b> 17, the control unit 9 writes the position information 32 and the hierarchy information 33 at this time in the storage unit 11 in association with each other. Specifically, when passing the first switching detection point a1 of the first movement shown in FIG. 2A, as shown in FIG. 3A, the storage unit 11 stores a1 as the position information 32. As information 33, S indicating switching from a weak hierarchy to a strong hierarchy is stored.

  Next, the process proceeds to step S18, where the control unit 9 determines whether switching has been detected two or more times within a predetermined distance L. Specifically, the distance between the current and previous switching points is calculated based on the position information 32 in the storage unit 11, and it is determined whether the current and previous switching points are within a predetermined distance L. In this case, since the point before the previous time is not stored at the first switching detection point of the first movement, it is determined as NO, and the process returns to step S10. When it determines with YES, it progresses to step S19.

  As described above, after switching to the strong hierarchy at the first switching detection point a1 of the first movement shown in FIG. 2A, the process returns from step S18 to step S10. And since it is the path | route which moves for the first time, it progresses to step S11. In step S11, since the currently moving route is already stored in the storage unit 11 as the route information 31, the process proceeds to step S13. In step S13, the weak hierarchy and the strong hierarchy are received from the antenna unit 1, and the process proceeds to step S14. In step S14, since the strong hierarchy is currently received, the process proceeds to step S20.

  In step S20, the control unit 9 determines whether or not the reception state of the mobile digital broadcast receiver is a reception state based on a strong hierarchy. Specifically, if the hierarchy of the video signal selected by the switching unit 7 is a strong hierarchy, the reception state is determined to be strong, and the process proceeds to step S21. Otherwise, the process returns to step S14. In this case, if it is before reaching the switching detection point b1 in FIG. 2A, an affirmative determination is made in step S20 and the process proceeds to step S21.

  In step S21, the control unit 9 determines whether the signal quality value is within a predetermined quality over a predetermined time. If it is not within the predetermined quality, reception by the strong hierarchy is continued. If it is determined that the signal quality value is within the predetermined quality for a predetermined time, the process proceeds to step S22. In this case, a negative determination is made in step S21 until it passes through the switching detection point b1, and if it passes through the switching detection point b1, an affirmative determination is made in step S21, that is, the second switching condition is satisfied, and the process proceeds to step S22. move on.

  In step S22, the control unit 9 switches the hierarchy of the broadcast signal received by the mobile digital broadcast receiver from the strong hierarchy to the weak hierarchy. Specifically, the switching unit 7 selects a video signal in the weak hierarchy, and switches the hierarchy of the video signal output to the video display unit 8 from the strong hierarchy to the weak hierarchy. Thereafter, the process proceeds to step S17.

  In step S <b> 17, the control unit 9 writes the position information 32 and the hierarchy information 33 at this time in association with each other in the storage unit 11. Specifically, when passing the second switching detection point b1 of the first movement shown in FIG. 2 (a), as shown in FIG. 3 (a), b1 is stored in the storage unit 11 as position information 32. Q indicating switching from the strong hierarchy to the weak hierarchy is stored as the hierarchy information 33.

  Next, the process proceeds to step S18, where the control unit 9 determines whether switching has been detected two or more times within a predetermined distance L. Specifically, the distance between the second switching detection point b1 of the first movement and the first switching detection point a1 is determined to be within a predetermined distance L, and the process proceeds to step S19.

  In step S <b> 19, the control unit 9 writes area information 34 in the storage unit 11 in association with the position information 32. Specifically, since the distance between the second switching detection point b1 of the first movement and the first switching detection point a1 is within a predetermined distance L, it is associated with a1 and b1 within the predetermined distance L. E1 is stored in the storage unit 11 as the area information 34, respectively. Thereby, when the distance between the switching detection points a1 and b1 adjacent to each other is within the range of the predetermined distance L, the switching detection points a1 and b1 are included in the same switching area in step S25 described later. To do. If the distance from the immediately preceding switching detection point is not within the predetermined distance L, nothing is stored in the area information 34 and the area remains blank. Then, it returns to step S10.

  Similarly, in the first movement, step S10 to step S22 are repeated, and switching between the weak hierarchy and the strong hierarchy is performed within a predetermined distance L at the switching detection points a1 to f1 as shown in FIG. If detected, the position information 32, the hierarchy information 33, and the area information 34 are sequentially stored in the storage unit 11, as shown in FIG. Since the information E1 is stored in the area information 34, the area indicated by the broken line in FIG. 2B becomes the switching area N1, and the second movement will be described below in the switching area N1. In addition, switching from a strong hierarchy to a weak hierarchy is prohibited.

(When moving the same route for the second time)
When moving the same route for the second time, NO is determined in step S10, and the process proceeds to step S23. In step S23, the control unit 9 determines whether the number of movements of the same route has exceeded the third time. Specifically, the route information 31 in the storage unit 11 is referred to and it is determined whether the fourth number of movements is stored. If the number of times of the fourth movement is stored, the process proceeds to step S24, and all the oldest information on the same route in the storage unit 11 is erased. If it is determined in step S23 that the number of movements of the same route does not exceed the third time, or after the processing in step S24, the process proceeds to step S25. When moving the same route for the second time, since the number of times of movement is the second time, a negative determination is made in step S23 and the process proceeds to step S25.

  In step S25, the control unit 9 sets a switching area. Specifically, when the same route is moved for the second time, the position information 32, the hierarchy information 33, and the area information 34 are stored in the storage unit 11 as shown in FIG. Since it is stored, the first detection point a1 where the same information E1 is continuously stored and P indicating switching from the weak hierarchy to the strong hierarchy is stored is referred to as the starting point. As described above, a switching area N1 is set that has a detection point f1 at which Q indicating the switching from the strong hierarchy to the weak hierarchy is stored last. As shown in FIG. 2B, a switching area N1 is set when moving the same route for the second time. Thereafter, the process proceeds to step S26, where the control unit 9 demodulates the broadcast signal received by the antenna unit 1 by the demodulation unit 3 to perform reception, and proceeds to step S27.

  In step S27, the control unit 9 determines whether or not the reception state of the mobile digital broadcast receiving apparatus is reception by a weak hierarchy. Specifically, if the hierarchy of the video signal selected by the switching unit 7 is a weak hierarchy, the reception state is determined to be a weak hierarchy and the process proceeds to step S28. Otherwise, the process proceeds to step S32. In this case, if it is before reaching the switching detection point a2 in FIG. 2B, an affirmative determination is made in step S27 and the process proceeds to step S28. In step S28, it is determined whether the signal quality value is within a predetermined quality. If it is within the predetermined quality, reception by the weak hierarchy is continued even during movement. The determination in step S28 is continuously performed, and when the signal quality value is not within the predetermined quality, the process proceeds to step S29. In this case, an affirmative determination is made in step S28 until the switching detection point a2 is passed, and if the switching detection point a2 is passed, a negative determination is made in step S28, that is, the first switching condition is satisfied, and the process proceeds to step S29. move on.

  In step S29, the control part 9 switches the hierarchy of the broadcast signal which a mobile digital broadcast receiver receives from a weak hierarchy to a strong hierarchy. Specifically, the switching unit 7 selects the video signal of the strong hierarchy and switches the hierarchy of the video signal output to the video display unit 8 from the weak hierarchy to the strong hierarchy. Then, it progresses to step S30.

  In step S <b> 30, the control unit 9 determines whether the route information 31 for the current number of movements is stored in the storage unit 11. If not stored, the process proceeds to step S31. If stored, the process proceeds to step S17.

  In step S <b> 31, the control unit 9 writes the currently moving route in the storage unit 11 as route information 31. The route information 31 includes the name of the route, information indicating whether it is up or down, and the number of movements. In this case, since the same route is moved for the second time, 2 is stored as the number of times of movement.

  Thereafter, the process proceeds to step S17, and the control unit 9 writes the position information 32 and the hierarchy information 33 at this time in association with each other in the storage unit 11. Specifically, when passing the first switching detection point a2 of the second movement shown in FIG. 2B, as shown in FIG. 3B, the storage unit 11 stores a2 as the position information 32. As information 33, S indicating switching from a weak hierarchy to a strong hierarchy is stored.

  Next, the process proceeds to step S18, where the control unit 9 determines whether switching has been detected two or more times within a predetermined distance L. In this case, since the point before the previous time is not stored at the first switching detection point of the second movement, it is determined as NO, and the process returns to step S10. When it determines with YES, it progresses to step S19.

  As described above, after switching to the strong hierarchy at the first switching detection point a2 of the second movement shown in FIG. 2 (b), the movement is continued, the process returns from step S18 to step S10, and is not the first moving path. Therefore, it progresses to step S23. In step S23, since the number of times of movement does not exceed the third time, the process proceeds to step S25.

  In step S25, the control unit 9 sets a switching area. Specifically, when the same route is moved for the second time, the switching area N1 is set by the first movement, as shown in FIG. 2B. In step S26, the weak hierarchy and the strong hierarchy are received from the antenna unit 1, and the process proceeds to step S27. In step S27, since the strong hierarchy is currently received, the process proceeds to step S32.

  In step S <b> 32, the control unit 9 determines whether the strong hierarchy is being received favorably. If it is in a good reception state, the process proceeds to step S33. If not well received, the process returns to step S27.

  In step S33, the control unit 9 determines whether the signal quality value is within the predetermined quality over a predetermined time. If it is not within the predetermined quality, reception by the strong hierarchy is continued. If it is determined that the signal quality value is within the predetermined quality for a predetermined time, that is, the second switching condition is satisfied, the process proceeds to step S34.

  In step S34, the control unit 9 determines whether the current location is within the switching area. In the case of the second movement, as shown in FIG. 2B, since the current location is the switching detection location b2 and the switching area is N1, the current location is determined to be within the switching area. On the other hand, when it is determined that the current location is not within the switching area, the process proceeds to step S35, where the control unit 9 selects the switching unit 7 and switches the reception from the strong hierarchy to the weak hierarchy. If it is determined in step S34 that the current location is within the switching area, step S35 is skipped, that is, even if the second switching condition is satisfied, switching from the strong hierarchy to the weak hierarchy is prohibited, and the process proceeds to step S30. .

  In step S <b> 30, the control unit 9 determines whether the currently moving route is stored in the storage unit 11 as the route information 31. If not stored, the process proceeds to step S31. If stored, the process proceeds to step S17. Since the route information 31 is already stored at the switching detection point b2 in the second movement of the same route, the process proceeds to step S17.

  In step S <b> 17, the control unit 9 writes the position information 32 and the hierarchy information 33 at this time in association with each other in the storage unit 11. Specifically, since it is the second switching detection point b2 of the second movement shown in FIG. 2B, as shown in FIG. 3B, b2 is stored in the storage unit 11 as the position information 32. Q indicating switching from the strong hierarchy to the weak hierarchy is stored as the hierarchy information 33.

  Next, the process proceeds to step S18, where the control unit 9 determines whether switching has been detected two or more times within a predetermined distance L. Specifically, the distance between the second switching detection point b2 of the second movement and the first switching detection point a2 is determined to be within a predetermined distance L, and the process proceeds to step S19.

  In step S <b> 19, the control unit 9 writes area information 34 in the storage unit 11 in association with the position information 32. Specifically, since the distance between the second switching detection point b2 of the second movement and the first switching detection point a2 is within a predetermined distance L, it is associated with a2 and b2 within the predetermined distance L. E2 is stored in the storage unit 11 as the area information 34, respectively. If the distance from the immediately preceding switching detection point is not within the predetermined distance L, nothing is stored in the area information 34 and the area remains blank. Then, it returns to step S10.

  Similarly, in the second movement, step S23 to step S34 and step S17 to step S19 are repeated, and as shown in FIG. 2B, the weak hierarchy within the predetermined distance L at the switching detection points a2 to d2. As shown in FIG. 3B, position information 32, hierarchy information 33, and area information 34 are sequentially stored in the storage unit 11, as shown in FIG. Then, switching from the weak hierarchy to the strong hierarchy is performed at the switching detection point a2, and thereafter, switching to the weak hierarchy is prohibited in step S34 in the switching area N1, so that the strong hierarchy remains in the switching area N1. is there.

(When moving the same route for the third time)
When moving the same route for the third time, NO is determined in step S10, and the process proceeds to step S23. In step S23, since the number of movements of the same route has not exceeded the third time, the process proceeds to step S25.

  In step S25, the control unit 9 sets a switching area. Specifically, when the same route is moved for the third time, the position information 32, the hierarchy information 33, and the area information 34 are stored in the storage unit 11 as shown in FIG. And stored as shown in FIG. 3B in the second movement. Together, the area where the information E1, E2 is continuous is set as a switching area N2, as shown in FIG. 2 (c). In this case, since the information E2 is included in the range of the information E1, the switching area N2 is the same area as the switching area N1. Then, switching from the weak tier to the strong tier is performed at the switching detection point a3. Thereafter, switching to the weak tier is prohibited in step S34 in the switching area N2, so that the strong tier remains in the switching area N2. is there.

(When moving the same route for the fourth time)
When moving the same route for the fourth time, NO is determined in the step S10, and the process proceeds to the step S23. In step S23, since the number of movements of the same route exceeds the third time, the process proceeds to step S24, and the control unit 9 deletes the oldest information. Specifically, all information shown in FIG. 3A is erased.

  In step S25, the control unit 9 sets a switching area. Specifically, when the same route is moved for the fourth time, the position information 32, the hierarchy information 33, and the area information 34 are stored in the storage unit 11 as shown in FIG. And is stored as shown in FIG. 3C in the third movement. Together, the area where the information E2, E3 is continuous is set as a switching area N3 as shown in FIG. 2 (d). Then, switching from the weak tier to the strong tier is performed at the switching detection point a4. Thereafter, switching to the weak tier is prohibited in step S34 in the switching area N3, so that the strong tier remains in the switching area N3. is there.

  In addition, each operation | movement when moving the same path | route 5 times or more is substantially the same as the case where it moves to the above-mentioned 4th time. In step S23, since the number of movements of the same route exceeds the third time, the process proceeds to step S24, and the control unit 9 deletes the oldest information. In step S25, the control unit 9 sets a switching area. More specifically, based on the position information 32, the hierarchy information 33, and the area information 34 stored in the storage unit 11 in the previous movement and the previous movement, both information En-1, En-2 (En- 1 is set as a switching area Nn-1 where the previous information (En-2 is the last information) is continuous. In the switching area Nn−1, even if the second switching condition is satisfied in step S33, switching to the weak hierarchy is prohibited in step S34. Remain in hierarchy.

According to the embodiment described above, the following operational effects can be obtained.
(1) A mobile digital broadcast receiving apparatus is mounted on a mobile body, and receives and switches between a weak hierarchy and a strong hierarchy of digital broadcasting based on a predetermined switching condition (antenna section 1) while the mobile body is moving. A channel selection unit 2, a demodulation unit 3, a demultiplexing unit 4, a weak layer decoding unit 5, a strong layer decoding unit 6, and a switching unit 7), and a storage unit 11 for storing information on switching detection points where the switching condition is satisfied, The area setting unit (control unit 9, step S25) for setting the switching area based on the information of the switching detection point stored in the storage unit 11 and the position of the moving body even when the switching condition is satisfied Is within the switching area, the control unit 9 (step S34) prohibits the receiving unit from switching from the strong hierarchy to the weak hierarchy. Since this is done, even when the moving body moves in an area where the strong and weak hierarchies are frequently switched, the frequency of interruption of the video / audio output of the broadcast signal between the strong and weak hierarchies is reduced. Can do.

(2) In the mobile digital broadcast receiving apparatus, the area setting unit (control unit 9, step S25) performs two switching when the distance or moving time between two switching detection points adjacent to each other is within a predetermined range. The switching area is set so that the detection points are included in the same switching area. Since it did in this way, the area where a strong hierarchy and a weak hierarchy are switched frequently can be set as the same switching area.

(3) In the mobile digital broadcast receiving apparatus, the switching condition includes a first switching condition for switching from the weak hierarchy to the strong hierarchy and a second switching condition for switching from the strong hierarchy to the weak hierarchy, The setting unit (control unit 9, step S25) sets the first switching detection point where the first switching condition is satisfied as the starting point of the switching area. Since it did in this way, the starting point of a switching area can be appropriately set to the first switching detection point switched from the weak hierarchy to the strong hierarchy.

(4) In the mobile digital broadcast receiving apparatus, the area setting unit (control unit 9, step S25) includes a switching detection point where the first switching condition for switching from the weak layer to the strong layer is satisfied, and the switching detection. For switching detection points that satisfy the second switching condition for switching from a strong layer to a weak layer next to a point, even if the distance or movement time between these points is outside the predetermined range, it is within the same switching area. The switching area is set so as to be included in. Since it did in this way, about the range which the reception state by the strong hierarchy continued in the past, it can set as a single switching area irrespective of the distance and movement time.

(5) In the mobile digital broadcast receiver, the storage unit 11 erases the information of the switch detection point corresponding to the oldest travel path when the mobile body moves on the same travel path more than a predetermined number of times. (Steps S23 and S24). Since it did in this way, the information of the switch detection point in the memory | storage part 11 can be hold | maintained in an appropriate amount.

(6) In the mobile digital broadcast receiving apparatus, if the control unit 9 has received a weak hierarchy before entering the switching area, the controller 9 continues to enter the weak hierarchy if the signal quality is good even after entering the switching area. After that, if the signal quality deteriorates, the receiving unit is switched and controlled to receive the strong layer (steps S27 and S28). Since it did in this way, even if it enters into a switching area, if a signal quality is good, a weak hierarchy can be received as much as possible.

(7) In the mobile digital broadcast receiving apparatus, the storage unit 11 distinguishes between uplink and downlink of the movement route and stores information of the switching detection points, respectively, and the area setting unit (control unit 9, step S25) A switching area is set for each of the up and down directions. Since it did in this way, an appropriate switching area can be set up and down on a moving route, respectively. For example, it is possible to appropriately cope with the case where the reception state differs between the up and down of the movement route depending on the position of the receiving antenna of the vehicle.

(Modification)
The present invention can be implemented by modifying the embodiment described above as follows.
(1) The information of the switching detection point between the weak layer and the strong layer of digital broadcasting is stored in the storage unit 11 and the switching area is set based on the information of the switching detection point. However, if the movement time between two detection points adjacent to each other is within a predetermined range, these may be set as the same switching area. Furthermore, regarding the detection point for switching from the weak hierarchy to the strong hierarchy and the detection point for switching from the strong hierarchy to the weak hierarchy detected next, the distance or movement time between them is not within the predetermined range. Even if it exists, you may set as the same switching area. In this way, the range in which the reception state by the strong hierarchy has been continued in the past can be set as a single switching area regardless of the distance and travel time.

(2) If the weak layer has been received before entering the switching area, the weak layer is continuously received after entering the switching area if the signal quality is good, and then strong if the signal quality deteriorates. The example of switching control so as to receive a hierarchy has been described. However, when entering the switching area, the control unit 9 may perform switching control so as to receive the strong hierarchy. In this way, the strong hierarchy can be received immediately when entering the switching area.

(3) The example in which the switching detection points are sequentially stored in the storage unit 11 while distinguishing the up and down of the moving route, and the switching area is set by distinguishing the up and down of the moving route. However, the switching detection point may be stored in the storage unit 11 and the switching area may be set without distinguishing whether the moving route is up or down.

(4) When the same route is moved for the third time, the first movement is stored in the storage unit 11 as shown in FIG. 3A, and the second movement is shown in FIG. 3B. The area in which the information E1 and E2 are continuously stored as the area information 34 is set as the switching area N2 as shown in FIG. That is, the switching area is set based on information for two times that traveled on the same route. However, the switching area may be set based on information for one time that traveled along the same route, or the switching area may be set based on information for three times or more that traveled along the same route. Alternatively, the switching area may be set by storing a predetermined number of times of switching detection point information when the moving body moves on the same route without storing the area information, and using them together.

  The present invention is not limited to the above-described embodiment, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention as long as the characteristics of the present invention are not impaired. It is. Moreover, it is good also as a structure which combined the above-mentioned embodiment and a some modification.

DESCRIPTION OF SYMBOLS 1 Antenna part 2 Channel selection part 3 Demodulation part 4 Demultiplexing part 5 Weak hierarchy decoding part 6 Strong hierarchy decoding part 7 Switching part 8 Image | video display part 9 Control part 10 GPS receiver 11 Memory | storage part

Claims (8)

A receiving unit mounted on a moving body, and switching and receiving a weak layer and a strong layer of digital broadcasting based on a predetermined switching condition while the moving body is moving;
A storage unit for storing information of a switching detection point where the switching condition is satisfied;
An area setting unit that sets a switching area based on the information of the switching detection point stored in the storage unit;
A control unit that prohibits the receiving unit from switching from the strong hierarchy to the weak hierarchy if the position of the moving object is within the switching area even when the switching condition is satisfied. Mobile digital broadcast receiver. The mobile digital broadcast receiver according to claim 1,
The area setting unit is configured to switch the two switching detection points so that the two switching detection points are included in the same switching area when a distance or a movement time between two switching detection points adjacent to each other is within a predetermined range. Mobile digital broadcast receiver for setting area. The mobile digital broadcast receiver according to claim 2,
The switching condition includes a first switching condition for switching from the weak hierarchy to the strong hierarchy, and a second switching condition for switching from the strong hierarchy to the weak hierarchy,
The area setting unit is a mobile digital broadcast receiving apparatus in which a first switching detection point where the first switching condition is satisfied is a starting point of the switching area. The mobile digital broadcast receiver according to claim 3,
The area setting unit may determine a distance between the switching detection point where the first switching condition is satisfied and the switching detection point where the second switching condition is satisfied next to the switching detection point. A mobile digital broadcast receiving apparatus that sets the switching area so that the switching area is included in the same switching area even when the traveling time is outside the predetermined range. In the mobile digital broadcast receiver according to any one of claims 1 to 4,
The storage unit is a mobile digital broadcast receiver that deletes information on the switching detection point corresponding to the oldest travel route when the mobile device travels on the same travel route more than a predetermined number of times. In the mobile digital broadcast receiver according to any one of claims 1 to 5,
When the control unit has received the weak layer before entering the switching area, if the signal quality is good even after entering the switching area, the control unit continuously receives the weak layer, and then the signal A mobile digital broadcast receiving apparatus that switches and controls the receiving unit to receive the strong layer when quality deteriorates. In the mobile digital broadcast receiver according to any one of claims 1 to 5,
The mobile digital broadcast receiver that controls the switching of the receiving unit so as to receive the strong layer when the control unit enters the switching area. In the mobile digital broadcast receiver according to any one of claims 1 to 7,
The storage unit distinguishes between up and down of the travel route and stores information of the switching detection point, respectively.
The area setting unit is a mobile digital broadcast receiving apparatus that sets the switching area by distinguishing between upward and downward of the moving route.

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