Radio device, radio device control method, and program

Abstract

To reduce a user's discomfort at the time of broadcasting switching at a radio device such as an on-vehicle radio device.SOLUTION: A radio device 100 includes: a first reception section (broadcast radio reception section) for receiving a radio signal of broadcast radio broadcasting; a second reception section (broadcast radio reception section) for receiving a radio signal of IP simultaneous radio broadcasting; a time deviation calculation section for calculating a time deviation between a broadcast radio sound based on the radio signal acquired by the first reception section and an IP radio sound based on the radio signal acquired by the second reception section; a postponement time prediction section for predicting a postponement time until switching from the broadcast radio sound to the IP radio sound on the basis of the time deviation; a time deviation calculation section for calculating an expansion rate on the basis of the postponement time; and an expansion / switching section that until an elapse of the postponement time, makes voice output be performed by expanding the broadcast radio sound using the expansion rate and, at the time of the elapse of the postponement time, performs switching to voice output of the IP radio sound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a radio device, a control method for a radio device, and a program. [Background technology]

[0002] Conventionally, in a car radio device, the signal reception environment changes as the vehicle in which the radio device is mounted moves, and therefore there is a demand for audio output control that takes such environmental changes into account.

[0003] Furthermore, radio devices receive broadcasts of the same content using different methods, and switch between these methods to output the received signals. For example, Patent Document 1 discloses a configuration for switching between an audio signal of a broadcast wave broadcast and an audio signal of an IP-type simulcast. In Patent Document 1, the playback speed of the broadcast wave broadcast is increased in consideration of the audio delay between the broadcast wave broadcast and the IP-type simulcast, thereby reducing the sense of discomfort felt by the user when switching between the two. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-201469 Summary of the Invention [Problem to be solved by the invention]

[0005] If the expansion rate of the audio playback speed before switching is increased as in Patent Document 1, the user may feel a sense of discomfort with the audio content in proportion to the increase in the expansion rate. On the other hand, if the expansion rate is set small, the time required for the timing of switching between the two broadcasts will increase. For example, the reception conditions of an in-vehicle radio device change constantly as the vehicle moves. If the reception conditions of the broadcast radio broadcast before switching further deteriorate and the broadcast radio broadcast can no longer be played, the system will switch to the IP radio broadcast at that point. In other words, waiting for the right timing to switch will result in a delay in the audio before and after the switch, which will ultimately cause discomfort to the user.

[0006] To address these two conflicting issues, Patent Document 1 sets the expansion rate within a range that does not cause discomfort to the user. However, it is difficult to simultaneously minimize the expansion rate for the audio output before switching and minimize the time required to synchronize the switching timing.

[0007] In view of the above-described problems, the present disclosure aims to reduce the sense of discomfort felt by users when switching broadcasts in a radio device such as an in-car radio device. [Means for solving the problem]

[0008] The present disclosure provides a radio device having a first receiving unit that receives a radio signal of a broadcast radio broadcast, a second receiving unit that receives a radio signal of an IP simulcast radio broadcast, a calculation unit that calculates a time difference between a broadcast radio sound based on the radio signal acquired by the first receiving unit and an IP radio sound based on the radio signal acquired by the second receiving unit, a prediction unit that predicts a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference, a calculation unit that calculates an expansion rate based on the grace period, and a switching unit that expands the broadcast radio sound using the expansion rate and outputs the audio until the grace period has elapsed, and switches to audio output of the IP radio sound when the grace period has elapsed.

[0009] The present disclosure also provides a control method for a radio device, comprising: a first receiving step of receiving a radio signal of a broadcast radio broadcast; a second receiving step of receiving a radio signal of an IP simulcast radio broadcast; a calculation step of calculating a time difference between the broadcast radio sound based on the radio signal acquired in the first receiving step and the IP radio sound based on the radio signal acquired in the second receiving step; a prediction step of predicting a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference; a calculation step of calculating an expansion rate based on the grace period; and a switching step of expanding the broadcast radio sound using the expansion rate and outputting audio until the grace period has elapsed, and switching to audio output of the IP radio sound when the grace period has elapsed.

[0010] The present disclosure also provides a program for causing a computer to execute a first receiving step of receiving a radio signal of a broadcast radio broadcast, a second receiving step of receiving a radio signal of an IP simulcast radio broadcast, a calculation step of calculating a time difference between the broadcast radio sound based on the radio signal acquired in the first receiving step and the IP radio sound based on the radio signal acquired in the second receiving step, a prediction step of predicting a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference, a calculation step of calculating an expansion rate based on the grace period, and a switching step of expanding the broadcast radio sound using the expansion rate and outputting the audio until the grace period has elapsed, and switching to the audio output of the IP radio sound when the grace period has elapsed.

[0011] Any combination of the above components, and conversion of the present disclosure into a method, device, system, storage medium, computer program, etc., are also valid aspects of the present disclosure. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to reduce the sense of discomfort felt by a user when switching broadcasts in a radio device such as an in-car radio device. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram showing a configuration example of a radio device according to a first embodiment; [Figure 2] Flowchart of switching process according to the first embodiment [Figure 3] Flowchart of grace period prediction process according to the first embodiment [Figure 4] FIG. 1 is a conceptual diagram illustrating a grace period according to the present disclosure. [Figure 5] FIG. 1 is a graph illustrating a method for predicting a grace period according to the first embodiment. [Figure 6] FIG. 1 is a conceptual diagram illustrating signal decompression according to the present disclosure. [Figure 7] Flowchart of grace period prediction process according to a modification of the first embodiment [Figure 8] FIG. 10 is a block diagram showing a configuration example of a radio device according to a second embodiment. [Figure 9] Flowchart of grace period prediction process according to the second embodiment [Figure 10] FIG. 10 is a graph illustrating the distance characteristics of received power according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, with appropriate reference to the accompanying drawings, embodiments specifically disclosing a radio device, a radio device control method, and a program according to the present disclosure will be described in detail. However, more detailed description than necessary may be omitted. For example, detailed description of already well-known matters or redundant description of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0015] <First Embodiment> [Device configuration] Fig. 1 is a block diagram showing an example of the configuration of a radio device according to the first embodiment. In Fig. 1, arrows indicate an example of the flow of signals to each block. Note that the configuration and signal flow shown in Fig. 1 are just examples.

[0016] The radio device 100 according to this embodiment is configured to be able to receive broadcast radio broadcasts and IP simulcast radio broadcasts (hereinafter also referred to as "IP radio broadcasts") that have the same service content as the broadcast broadcasts. The broadcast radio broadcasts and IP radio broadcasts each include radio signals corresponding to a plurality of services, and a selected service from among these is output as audio. In this embodiment, it is assumed that the radio device 100 is able to receive broadcast radio broadcasts corresponding to a plurality of services and IP radio broadcasts corresponding to at least one of those services.

[0017] The radio device 100 according to this embodiment is assumed to be, for example, an in-vehicle radio device mounted in a vehicle (not shown) and configured to be operable by a user. The in-vehicle radio device may be configured as a single device that outputs radio signals, or may be configured as one function of a so-called navigation device. The term "vehicle" is not limited to a passenger car, but may refer to any mobile object, such as a motorcycle, bus, or truck. The configuration shown in FIG. 1 is an example, and one component may be divided into multiple components, or multiple components may be integrated into one component. Only components related to the functions of this embodiment are shown here, and the device may be configured to provide other functions.

[0018] Antenna 101 receives radio signals related to broadcast radio broadcasting and transmits them to broadcast radio receiving unit 103. Antenna 101 receives radio signals related to broadcast radio broadcasting in a predetermined frequency band transmitted from a surrounding base station, but the frequency band and standard are not particularly limited. Antenna 102 receives radio signals related to IP radio broadcasting and transmits them to IP radio receiving unit 104.

[0019] The broadcast radio receiving unit 103 provides the received radio signal to the broadcast radio decoding unit 105. The IP radio receiving unit 104 provides the received radio signal to the IP radio decoding unit .

[0020] The broadcast radio decoding unit 105 acquires and decodes a radio signal having a frequency specified by a user's station selection, etc., from among the radio signals received by the broadcast radio receiving unit 103. The radio signal having the specified frequency is acquired, for example, by filtering. The broadcast radio decoding unit 105 then transmits the decoded radio signal as broadcast radio sound to the time offset calculation unit 107 and the expansion / switching unit 109. The broadcast radio decoding unit 105 also provides information about the reception status of the received radio signal to the grace period prediction unit 108. The broadcast radio decoding unit 105 may further perform noise identification and noise removal processing.

[0021] The IP radio decoding unit 106 acquires a radio signal of a frequency specified by a user's station selection, etc., from the radio signals received by the IP radio receiving unit 104, and decodes the received radio signal. Then, the IP radio decoding unit 106 transmits the decoded radio signal to the time offset calculation unit 107 and the expansion / switching unit 109 as IP radio sound.

[0022] The time offset calculation unit 107 compares the acquired broadcast radio sound with the IP radio sound and calculates the time offset between them. An example of a method for calculating the time offset will be described later. The time offset calculation unit 107 then transmits information about the calculated time offset to the decompression / switching unit 109.

[0023] The grace period prediction unit 108 predicts the grace period until switching based on the acquired reception status. An example of a method for predicting the grace period will be described later. Then, the grace period prediction unit 108 transmits the predicted grace period to the extension / switching unit 109.

[0024] The expansion / switching unit 109 controls expansion and switching of the radio sound to be output based on the acquired radio sound and time information, and outputs the radio sound to the audio output unit 110. The audio output unit 110 outputs the acquired radio sound as audio using a speaker or the like.

[0025] Each block shown in FIG. 1 may be realized by, for example, a control unit or a storage unit (not shown). The control unit (not shown) may be configured using, for example, a central processing unit (CPU), a micro processing unit (MPU), a digital signal processor (DSP), a graphical processing unit (GPU), or a field programmable gate array (FPGA). The storage unit (not shown) is a storage area for storing and holding various data, and may be configured, for example, by a non-volatile storage area such as a read only memory (ROM) or a hard disk drive (HDD), or a volatile storage area such as a random access memory (RAM). For example, the control unit may realize some or all of the functions of the blocks shown in FIG. 1 by reading and executing various data and programs stored in the storage unit.

[0026] [Processing flow] (Switching process) Fig. 2 illustrates a flowchart of the switching process according to this embodiment. This process flow is realized by the cooperation of the blocks of radio device 100 shown in Fig. 1, but for simplicity, the process will be described collectively as being performed by radio device 100.

[0027] In this example, we will assume that broadcast radio broadcasts and IP radio broadcasts with the same service content are receivable, and that switching from broadcast radio broadcasts to IP radio broadcasts is required. Generally, when comparing broadcast radio broadcasts and IP radio broadcasts (IP simulcasts) with the same service content, IP radio broadcasts can have delays when outputting audio, due to factors such as the longer decoding process required for IP radio broadcasts. This explanation will be based on the assumption that IP radio sound is delayed.

[0028] The radio device 100 receives a selection of a desired service from among a plurality of services that can be received via broadcast radio (step S201). The selection here may be, for example, received from a user using a user interface provided in the radio device 100, or the radio device 100 may select an arbitrary service according to the user's preferences.

[0029] The radio device 100 receives the radio signal of the broadcast radio service selected in step S201 and outputs it as sound (step S202).

[0030] The radio device 100 checks whether there is an IP simulcast corresponding to the service selected in step S201 (step S203). The presence or absence of an IP simulcast can be determined based on, for example, information attached to the radio signal of the broadcast radio broadcast.

[0031] As a result of the check in step S203, the radio device 100 determines whether or not a corresponding IP simulcast is available (step S204). If a corresponding IP simulcast is available (step S204: YES), the processing of the radio device 100 proceeds to step S205. On the other hand, if a corresponding IP simulcast is not available (step S204: NO), this processing flow ends. In this case, audio output of the broadcast service accepted in step S201 will continue until a stop instruction for the radio device 100 is received, a change in the service is made, or the reception conditions of the broadcast signal deteriorate so that audio output is no longer possible.

[0032] The radio device 100 receives and decodes the corresponding IP simulcast radio signal (step S205).

[0033] The radio device 100 determines whether or not there is data necessary for calculating the time difference based on the sound data of the broadcast received in step S202 and the sound data of the IP simulcast decoded in step S205 (step S206). The data necessary for calculating the time difference may be, for example, reception accuracy information or a reception period of the IP simulcast, and the determination may be made by comparing these with a threshold value. If there is sound data necessary for calculating the time difference (step S206: YES), the processing of the radio device 100 proceeds to step S207. On the other hand, if there is no sound data necessary for calculating the time difference (step S206: NO), this processing flow ends. In this case, the radio device 100 may operate in the same way as when there is no corresponding IP simulcast.

[0034] The radio device 100 calculates the time difference between the output of the broadcast radio sound and the output of the IP radio sound, i.e., the time offset (step S207). The time offset is calculated based on the correlation between the signals. Because the content is the same, the signal waveform characteristics are nearly identical. Therefore, by calculating the correlation between the broadcast radio sound and the IP radio sound, it is possible to derive the time offset. The method for deriving the signal correlation here may be any known method and is not particularly limited.

[0035] The radio device 100 performs a grace period prediction process (step S208). Details of this process will be described later with reference to FIG.

[0036] The radio device 100 calculates the extension rate based on the grace period calculated in step S209 (step S209). An example of a method for calculating the extension rate will be described later with reference to FIG.

[0037] The radio device 100 performs time stretch processing on the broadcast radio sound based on the expansion rate calculated in step S209 (step S210). An example of the time stretch processing will be described with reference to FIG.

[0038] Based on the time difference calculated in step S207, the radio device 100 determines whether or not it is time to switch radio broadcasts (step S211). The switching timing will be described with reference to FIG. 6, etc. If it is time to switch (step S211: YES), the process of the radio device 100 proceeds to step S213. On the other hand, if it is not time to switch (step S211: NO), the process of the radio device 100 proceeds to step S212.

[0039] The radio device 100 compares the reception conditions of the broadcast radio broadcasts and IP radio broadcasts with the reception conditions of the broadcast radio broadcasts and IP radio broadcasts when the grace period was calculated in step S208 and determines whether they have changed (step S212). This determination may be made based on whether the reception conditions of only one of the radio broadcasts have changed. Alternatively, the change may be determined based on whether the reception conditions have worsened. If the reception conditions have changed (step S212: YES), the radio device 100 returns to step S207 and repeats the process. On the other hand, if the reception conditions have not changed (step S212: NO), the radio device 100 returns to step S211 and repeats the process.

[0040] The radio device 100 switches the audio output from the broadcast radio broadcast to the IP simulcast received in step S205 (step S213). Then, this processing flow ends. In this case, audio output of the received IP simulcast service will continue until the radio device 100 receives an instruction to stop the broadcast radio broadcast, the service is changed, or the reception condition of the IP simulcast deteriorates and playback becomes impossible.

[0041] (Grace time prediction process) 3 is a flowchart of the grace period prediction process according to this embodiment, which corresponds to step S208 in FIG.

[0042] The radio device 100 acquires information about the reception state and characteristics of the broadcast waves (step S301). Specifically, the information acquired here includes historical information about the reception level of the broadcast of the selected service, i.e., the amount of change.

[0043] Based on the information received in step S301, the radio device 100 predicts the grace period during which reception of the broadcast wave can be continued (step S302). The method for predicting the grace period will be described later with reference to Figures 4 and 5. Then, this processing flow ends, and the process proceeds to step S209 in Figure 2.

[0044] [Grace time and elongation rate] The grace period for switching from broadcast radio broadcasting to IP radio broadcasting according to this embodiment will be described using FIG. 4. As shown in FIG. 4, the radio device 100 according to this embodiment is mounted on a mobile object such as a vehicle 400 and configured to be mobile. For broadcast radio broadcasting, radio signals are transmitted from a base station 401 including an antenna tower, and an effective range 402 within which the radio signals can be received is defined. The effective range 402 can vary depending on various factors such as the height of the antenna tower, signal strength, and topography. Furthermore, even within the effective range 402, the reception level that the radio device 100 can receive can vary due to the above-mentioned factors. The higher the reception level, the more stable the radio sound can be output.

[0045] For simplicity of explanation, only one vehicle 400 and one base station 401 are shown here, but there are actually a plurality of these. In addition, the effective ranges 402 of a plurality of radio broadcasts also overlap.

[0046] Vehicle 400 can move in and out of effective range 402. The example in Fig. 4 shows a situation in which vehicle 400 is moving toward the outside of effective range 402 of a broadcast of a certain service. In this case, the time until vehicle 400 moves out of effective range 402 is set as grace time Tf.

[0047] Fig. 5 is a graph illustrating an example of a method for predicting the grace period. The horizontal axis represents time, and the vertical axis represents the reception level. The reception level S0 corresponds to the reception level at the edge of the effective range 402 shown in Fig. 4, and it will be explained that at reception levels lower than this, radio sound cannot be output or output quality cannot be guaranteed.

[0048] Two points are shown: the reception level S(t) at a certain time t of the radio device 100, and the reception level S(tz) at a time (tz) a period z before the time t. These pieces of information are assumed to be acquired as appropriate as historical information. The period z is assumed to have a predetermined time width. The change in reception level per unit time dSt shown in FIG. 5 can be defined by the following equation (1).

[0049]

number

[0050] Then, based on the amount of change dSt, the time from the current time t until the reception level reaches S0 is calculated as the grace period Tf. Note that the prediction method here is just an example, and the grace period may be calculated based on, for example, three or more pieces of historical information, or other prediction methods may be used. Furthermore, a formula other than the above formula (1) may also be used. This process is performed according to the processing flow of FIG. 3.

[0051] 4 and 5 show an example in which the vehicle 400 equipped with the radio device 100 is moving toward the outside of the effective range 402. On the other hand, if the vehicle 400 is moving closer to the base station 401 within the effective range 402, the reception level is expected to increase, and the output quality of the broadcast is expected to improve. In such a case, the grace period begins to increase. Therefore, if the grace period increases and exceeds a certain threshold, part of the processing in FIG. 2 may be suspended for a predetermined period of time.

[0052] Moreover, instead of the reception level, a bit error rate (BER) may be used, or the BER and the reception level may be combined.

[0053] Furthermore, an expansion rate is derived based on the above-mentioned grace period. Fig. 6 is a conceptual diagram for explaining the expansion rate according to this embodiment and the stretching process using the expansion rate. The upper graph in Fig. 6 shows an example of the signal waveform of the broadcast currently outputting audio. The lower graph in Fig. 6 shows an example of the signal waveform of the IP radio broadcast to which switching will be made.

[0054] As mentioned above, IP radio broadcasts tend to output audio later than broadcast broadcasts. This delay is indicated as the time lag Td. When switching from broadcast broadcasts to IP radio broadcasts, the time lag is taken into consideration and the broadcast broadcast signal is expanded at an expansion rate R for a certain period before the switch. The expansion period is the aforementioned grace period Tf. In this embodiment, the expansion rate R is defined by the following equation (2):

[0055]

number

[0056] In the example of Figure 6, the broadcast is switched to the IP radio broadcast at time t3, and the radio signal of the previous broadcast is expanded and synchronized at an expansion rate R. The expansion rate R is adjusted in accordance with changes in the time lag Td and the grace period Tf.

[0057] For example, if the time lag is 1 minute (=60 seconds) and the predicted grace period is 40 minutes, the extension rate may be set to 2.5%. Also, if the time lag is 1 minute (=60 seconds) and the predicted grace period is 20 minutes, the extension rate may be set to 5%. If the time lag is 1 minute (=60 seconds) and the predicted grace period is 10 minutes, the extension rate may be set to 10%. In other words, if the time lag is 60 seconds and the extension rate is 10%, it will take 600 seconds for the switch to occur.

[0058] The method for calculating the extension rate is not limited to the above. For example, if the grace period Tf is less than or equal to 0, that is, if there is no possibility that the radio device 100 will go outside the valid range, the extension rate R may be set to 1. In other words, the extension rate may be set so that no extension occurs. Alternatively, a predetermined minimum extension rate Rmin may be used.

[0059] Furthermore, a maximum extension rate Rmax may be predefined for the extension rate R. If the calculated extension rate R exceeds the maximum extension rate Rmax, the following processing may be performed. Here, the case where the maximum extension rate Rmax is exceeded is assumed to be, for example, a case where the time lag Td is long or a case where the grace period Tf is short. A long time lag Td corresponds to a case where a long time is required to synchronize the radio signal for the switching timing. A short grace period Tf corresponds to a case where the time until the radio device 100 goes outside the effective range is short.

[0060] For example, if R>Rmax, the radio signal may be expanded at the maximum expansion rate Rmax. The maximum expansion rate Rmax is set within a range that does not cause discomfort to the user due to the expansion. The maximum expansion rate Rmax may also be changed depending on the content of the radio broadcast service.

[0061] Furthermore, methods other than extension may be combined to ensure time until the radio signal is switched. For example, an output interval in which a signal different from the radio signal is output may be inserted to fill the time until the grace period has elapsed. An example of an output interval may be a silent interval. In this case, the insertion position of the silent interval may be adjusted depending on the content of the service. For example, a silent interval may be inserted between songs. Alternatively, an announcement interval of a predetermined duration may be inserted instead of a silent interval. Alternatively, audio information preset by the user may be used. This makes it possible to supplement the output until the switching timing without extending the broadcast radio sound.

[0062] Furthermore, if the time lag Td is large, control may be performed so that extension is not performed. A large time lag Td refers to, for example, when the time lag Td is 10% or more of the grace period Tf. In this case, if the accuracy of the derived time lag Td or grace period Tf is low, control may be performed so that the determination is suspended until a certain accuracy is reached, and extension is performed at the maximum extension rate Rmax. Note that accuracy here corresponds to the reliability of the derived result, and data for a certain period of time or more, i.e., when derived without obtaining historical information, may be treated as having low accuracy.

[0063] Furthermore, if a time lag Td occurs, it is not necessarily necessary to perform time stretching, i.e., extending the broadcast radio sound. For example, if the time lag Td is equal to or less than a predetermined threshold, the impact on the user's discomfort when switching is small, and time stretching may be omitted.

[0064] (Variation 1) The above process is based on the assumption that a service switches between one broadcast broadcast and one corresponding IP radio broadcast. However, in some regions, the same service content may be provided on multiple channels within the broadcast broadcast.

[0065] In consideration of the above-mentioned cases, as a modified example of this embodiment, we will explain a configuration in which the grace period is predicted based on multiple broadcasts providing the same service, and then switching to IP radio broadcasting. The system configuration example shown in Figure 1 and the switching process flow shown in Figure 2 are assumed to be the same.

[0066] Fig. 7 shows a flowchart of the grace period calculation process according to this modification. The process flow shown in Fig. 7 is executed in place of the process flow shown in Fig. 3 described above. For convenience, the broadcast broadcast currently being output as audio among multiple broadcasts with the same service content will be referred to as the "broadcast wave currently being output." Furthermore, the broadcast broadcast that can be switched among the multiple broadcasts will be referred to as the "alternative broadcast wave."

[0067] The radio device 100 acquires information about the reception state and characteristics of the broadcast wave being output (step S701). The information acquired here may be the same as that acquired in step S301 of FIG.

[0068] Based on the information received in step S701, the radio device 100 predicts the grace period during which reception of the currently output broadcast wave can be continued (step S702). The prediction method here may be the same as that in step S302 of Fig. 3. For convenience, the grace period Tf predicted in this step is also referred to as the "first grace period."

[0069] The radio device 100 acquires information about the reception state and characteristics of the alternative broadcast wave (step S703). The information acquired here may be the same as that in step S701.

[0070] Based on the information received in step S703, the radio device 100 predicts the grace period during which reception of the alternative broadcast wave can continue (step S704). The prediction method here may be the same as that in step S702. For convenience, the grace period Tf' predicted in this step is also referred to as the "second grace period."

[0071] The radio device 100 corrects the grace period predicted in step S702 with the grace period predicted in step S704 (step S705). For example, the grace periods Tf and Tf' may be compared, and the longer one may be set as the grace period. Alternatively, the grace periods Tf and Tf' may be compared, and if Tf' is longer, the correction may be performed by multiplying Tf by a predetermined coefficient. The predetermined coefficient may be a fixed value, or may be derived based on the difference between the grace periods Tf and Tf'.

[0072] Although the example described here is one case where there is one alternative broadcast, it is also possible that there are more alternative broadcast waves. In such a case, the one with the longest grace period among them may be used. Alternatively, the predetermined coefficient may be adjusted depending on the number of alternative broadcast waves. Then, this processing flow ends, and the process proceeds to step S209 in FIG. 2.

[0073] If the sound quality or reception level of the broadcast currently being output deteriorates, the radio device 100 may perform control to switch to an alternative broadcast wave of higher quality before switching to IP radio broadcast.

[0074] As described above, a radio device (e.g., 100) according to this embodiment includes a first receiving unit (e.g., 101, 103, 105) that receives a radio signal of a broadcast radio broadcast, a second receiving unit (e.g., 102, 104, 105) that receives a radio signal of an IP simulcast radio broadcast, a calculation unit (e.g., 107) that calculates a time difference between the broadcast radio sound based on the radio signal acquired by the first receiving unit and the IP radio sound based on the radio signal acquired by the second receiving unit, a prediction unit (e.g., 108) that predicts a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference, a calculation unit (e.g., 109) that calculates an expansion rate based on the grace period, and a switching unit (e.g., 109, 110) that expands the broadcast radio sound using the expansion rate until the grace period has elapsed and outputs the audio, and then switches to the IP radio sound when the grace period has elapsed. This configuration makes it possible to reduce the sense of discomfort felt by a user when switching broadcasts in a car-mounted radio device or the like. In particular, it is possible to simultaneously minimize the expansion rate of the audio output before switching and the time required to synchronize the switching timing.

[0075] In addition, in the radio device, the prediction unit may predict the grace period based on a change per unit time in the reception level of the broadcast radio signal and a predetermined reception level. This configuration makes it relatively easy to predict the grace period until switching from broadcast radio broadcasting to IP radio broadcasting.

[0076] In addition, in the radio device, the broadcast radio broadcast may include multiple radio signals having the same content, the calculation unit may calculate a time offset of the IP radio sound relative to each of the broadcast radio sounds based on the multiple radio signals, and the prediction unit may predict the grace period based on the time offset of the IP radio sound relative to each of the broadcast radio sounds based on the multiple radio signals. With this configuration, it is possible to calculate the grace period before switching to IP radio, taking into account multiple broadcast radio broadcasts having the same content.

[0077] Furthermore, in the radio device, if the grace period exceeds a predetermined threshold, the calculation unit may set the expansion rate to 1 or a predetermined minimum expansion rate. With this configuration, if there is a low possibility of switching from broadcast radio broadcasting to IP radio broadcasting, it is possible to control the output of the radio sound of the broadcast radio broadcasting so that it is close to the original signal.

[0078] In addition, in the radio device, if the expansion rate calculated based on the grace period exceeds a predetermined maximum expansion rate, the calculation unit may set the expansion rate to the maximum expansion rate. With this configuration, by controlling the output of the broadcast radio broadcast using the upper limit of the expansion rate, it is possible to suppress discomfort felt by the user due to expansion.

[0079] In addition, in the radio device, if the expansion rate calculated based on the grace period exceeds a predetermined maximum expansion rate, the switching unit may insert a predetermined output section into the broadcast radio sound before the grace period expires, instead of expanding the sound at the expansion rate. With this configuration, by inserting an arbitrary output instead of expanding the sound, it is possible to reduce the discomfort felt by the user due to the expansion.

[0080] In addition, in the radio device, the predetermined output period may be a silent period or an announcement period including a predetermined voice message. With this configuration, it is possible to adjust the switching timing using information that does not cause discomfort when outputting radio broadcasts.

[0081] <Embodiment 2> A second embodiment of the present disclosure will be described. In the second embodiment, a radio device is capable of acquiring additional information from a vehicle or the like, and a form using this information will be described.

[0082] [System Configuration] Fig. 8 is a block diagram showing an example configuration of a radio device 800 according to the second embodiment. Components that overlap with those in Fig. 1 shown in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted. As differences from the example configuration in Fig. 1 shown in the first embodiment, radio device 800 further includes a communication unit 801, a vehicle position information acquisition unit 802, and an antenna position information database 803.

[0083] The communication unit 801 is a communication interface for communicating with an external system (not shown). Here, the description will be made assuming that the communication unit 801 is a position sensor for acquiring position information of the vehicle 400 in which the radio device 800 is mounted. The position sensor may be, for example, a position sensor using a Global Navigation Satellite System (GNSS) represented by a Global Positioning System (GPS). The vehicle position information acquisition unit 802 acquires the position information of the radio device 800 via the communication unit 801. The acquired position information is provided to the grace time prediction unit 108.

[0084] The antenna position information database 803 is a database in which information about base stations is recorded. The antenna position information database 803 may include, for example, the position (latitude, longitude) of the antenna tower of the base station, the transmission power of the antenna tower, the antenna gain of the antenna tower, and the antenna height of the antenna tower. The contents of the antenna position information database 803 may be updated as appropriate by a processing unit (not shown). Alternatively, the antenna position information database 803 may be provided outside the radio device 800, and the information may be acquired as needed via the communication unit 801 or the like. Various pieces of information acquired by referring to the antenna position information database 803 are provided to the grace period prediction unit 108.

[0085] The grace period prediction unit 108 according to this embodiment predicts the grace period using the reception status of the radio signal from the broadcast radio decoding unit 105, as well as the position information of the vehicle 400 and the antenna position information.

[0086] 9 is a flowchart of the grace period calculation process according to this embodiment, which is executed in place of the process shown in FIG.

[0087] The radio device 800 acquires information about the reception state and characteristics of the broadcast wave that is currently being output (step S901). The information acquired here may be the same as that acquired in step S301 of FIG.

[0088] Based on the information received in step S901, the radio device 800 predicts a grace period during which reception of the broadcast wave currently being outputted can be continued (step S902). The prediction method here may be the same as that in step S302 of Fig. 3. The predicted grace period is defined as grace period Tfbr.

[0089] The radio device 800 refers to the antenna position information database 803 and acquires information about the antenna tower that is currently outputting audio (step S903). The radio device 800 also acquires information about its own antenna. Examples of the information about its own antenna include antenna reception power, antenna gain, reception limit power, and antenna height. The information about its own antenna may be stored in advance in a storage unit (not shown) of the radio device 800.

[0090] The radio device 800 acquires its own location information via the vehicle location information acquisition unit 802 (step S904).

[0091] The radio device 800 calculates the maximum allowable loss of radio signal propagation using the antenna tower information acquired in step S903 and the information about the radio device's antenna acquired in step S904 (step S905). The radio wave propagation loss Los can be defined by the following relational expression (3):

[0092]

number

[0093] Furthermore, if the propagation loss Loss (that is, the maximum allowable loss) when the received power Pr becomes the reception level S0, which is the reception limit power, is set to Losw, the following relational expression (4) can be defined.

[0094]

number

[0095] The radio device 800 derives the distance Rw at which the propagation loss of the radio wave becomes the maximum allowable loss Losw calculated in step S905 (step S906). The distance Rw at which the maximum allowable loss Losw becomes can be derived from a propagation loss formula or data. For example, known methods such as flat ground propagation loss (two-beam model), spherical diffraction propagation loss, the Okumura-Hata model, and Recommendation ITU-RP.1546-6 can be used.

[0096] Figure 10 is a graph showing the relationship between received power and distance. The vertical axis represents received power [dB], and the horizontal axis represents distance [km]. Figure 10 shows an example of the results of calculating received power using the well-known Okumura-Hata model and the formula for spherical diffraction propagation loss. Since this calculation method is well-known, a detailed explanation will be omitted, but based on the relationship shown in Figure 10, it is possible to derive the distance between the antenna tower and the radio device at which the propagation loss of the radio wave is the maximum allowable loss (Losw).

[0097] The radio device 800 calculates the distance between the antenna tower and the device itself, using the antenna tower information acquired in step S903 and the location information of the device itself acquired in step S904 (step S907).

[0098] Radio device 800 calculates the amount of change per unit time of the distance calculated in step S907 (step S908). The calculated distance may be stored as history information as appropriate, and the amount of change may be calculated based on this history information.

[0099] Based on the amount of change calculated in step S908, radio device 800 calculates a predicted reception time for the broadcast wave being received (step S909). The predicted reception time corresponds to the time allowed until the radio signal of the broadcast from the antenna tower leaves the receivable range, calculated based on the information from the antenna tower and the information from radio device 100. The predicted reception time Tfx here can be calculated, for example, using the following equation (5):

[0100]

number

[0101] The radio device 100 corrects the grace period Tfbr predicted in step S902 by the predicted reception period Tfx predicted in step S909 (step S910). For example, the grace period Tfbr and the predicted reception period Tfx are weighted by the following equation (6) to calculate the grace period.

[0102]

number

[0103] The correction method is not limited to the above, and other methods may be used. For example, the reliability of each of the grace period Tfbr and the predicted reception period Tfx may be calculated, and the one with the higher reliability may be used as the grace period. In this case, the reliability may be determined based on, for example, the deviation from the average value of past predicted periods. Then, this processing flow ends, and the process proceeds to step S209 in FIG. 2.

[0104] As described above, a radio device (e.g., 800) according to this embodiment further includes an acquisition unit (e.g., 801, 802, 803) that acquires information about the antenna tower transmitting the broadcast radio signal and the location information of the radio device. The prediction unit further derives the distance resulting in an acceptable propagation loss for the radio signal from the antenna tower and the amount of change in distance per unit time between the antenna tower and the radio device based on the antenna tower information and the location information. Using the distance resulting in an acceptable propagation loss and the amount of change in distance per unit time, the prediction unit calculates the estimated reception time until the radio device goes out of range for receiving the radio signal from the antenna tower. The prediction unit corrects the estimated grace period based on the time difference using the estimated reception time. This configuration further improves the accuracy of the predicted grace period using information about the antenna tower and the radio device itself. This makes it possible to identify a more appropriate timing for switching from broadcast radio broadcasting to IP radio broadcasting.

[0105] In the radio device, the prediction unit may perform correction by weighting the delay time predicted based on the time difference and the predicted reception time. This configuration enables correction of the delay time using a simple method.

[0106] In addition, in the radio device, the prediction unit may perform correction based on the reliability of the grace period predicted based on the time difference and the predicted reception time. With this configuration, by using the reliability according to each prediction result, it is possible to further improve the accuracy of the grace period.

[0107] <Other embodiments> In the above embodiment, an example of switching between broadcast and IP radio broadcast has been described, but the present disclosure is not limited to this combination. The configuration of the present disclosure can be applied to any combination in which a delay may occur when switching between the radio broadcasts.

[0108] Furthermore, in the example of FIG. 5, the reception level S0 is used as the threshold for reception, but this is not limiting. For example, the reception level S0 may be corrected. For example, in an environment where alternative broadcasts are available, radio signals may be subject to interference due to multipath or adjacent channels. Taking such influences into consideration, the reception level S0 may be corrected by multiplying it by a predetermined coefficient to make it greater than 1. Alternatively, the predetermined coefficient may be changed according to the moving speed of the radio device. For example, if a vehicle equipped with the radio device is traveling at a certain speed or above, the predetermined coefficient may be controlled to be higher. Furthermore, the predetermined coefficient may be increased or decreased according to the signal interference resistance indicated by the codec information of the broadcast wave.

[0109] In addition, the functions of one or more of the above-described embodiments can be realized by supplying a program and application to a system or device via a network or storage medium, and having one or more processors in the computer of the system or device read and execute the program.

[0110] Alternatively, it may be realized by a circuit that realizes one or more functions (for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array)).

[0111] Furthermore, in this specification, the terms "first" and "second" are used to distinguish from other elements for explanatory purposes and are not intended to be interpreted as being limited to specific components. Therefore, it will be understood that these terms may be interpreted appropriately depending on the configuration to which the invention according to the present disclosure is applied.

[0112] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present disclosure is not limited to these examples. It is clear to those skilled in the art that various modifications, alterations, substitutions, additions, deletions, and equivalents may be made within the scope of the claims, and it is understood that these also fall within the technical scope of the present disclosure. Furthermore, the components of the various embodiments described above may be combined in any manner without departing from the spirit of the invention.

[0113] (Addendum) The above description of the embodiments discloses the following techniques. (Technology 1) a first receiving unit for receiving a radio signal of a broadcast radio broadcast; a second receiving unit that receives radio signals of IP simulcast radio broadcasts; a calculation unit that calculates a time difference between a broadcast radio sound based on the radio signal acquired by the first receiving unit and an IP radio sound based on the radio signal acquired by the second receiving unit; a prediction unit that predicts a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference; a calculation unit that calculates an extension rate based on the grace time; a switching unit that expands the broadcast radio sound using the expansion rate and outputs the sound until the grace time has elapsed, and switches to outputting the IP radio sound when the grace time has elapsed; A radio device having: This configuration can reduce the sense of discomfort felt by users when switching broadcasts in a car radio device, etc. In particular, it can minimize both the expansion rate of the audio output before switching and the time required to synchronize the switching timing.

[0114] (Technology 2) The radio device according to technique 1, wherein the prediction unit predicts the grace period based on a change per unit time in the reception level of the radio signal of the broadcast radio broadcast and a predetermined reception level. This configuration makes it relatively easy to predict the grace period until switching from broadcast radio broadcasting to IP radio broadcasting.

[0115] (Technology 3) the broadcast radio transmission comprises a plurality of radio signals of the same content; the calculation unit calculates a time offset of the IP radio sound relative to each of the broadcast radio sounds based on the plurality of radio signals; The radio device according to Technology 1 or Technology 2, wherein the prediction unit predicts the grace period based on a time offset of the IP radio sound relative to each of the broadcast radio sounds based on the plurality of radio signals. With this configuration, it is possible to calculate the grace period before switching to IP radio, taking into account multiple broadcast radio broadcasts of the same content.

[0116] (Technology 4) The radio device according to any one of Techniques 1 to 3, wherein the calculation unit sets the extension rate to 1 or a predetermined minimum extension rate when the grace time exceeds a predetermined threshold. According to this configuration, when the possibility of switching from broadcast radio broadcasting to IP radio broadcasting is low, it is possible to control the output of the radio sound of the broadcast radio broadcasting so that it is close to the original signal.

[0117] (Technology 5) The radio device according to any one of Technology 1 to Technology 3, wherein, when the extension rate calculated based on the grace time exceeds a predetermined maximum extension rate, the calculation unit sets the extension rate to the maximum extension rate. According to this configuration, by controlling the output of the broadcast radio broadcast using the upper limit of the expansion rate, it is possible to suppress the discomfort felt by the user due to expansion.

[0118] (Technology 6) When the expansion rate calculated based on the grace period exceeds a predetermined maximum expansion rate, the switching unit inserts a predetermined output section into the broadcast radio sound before the grace period has elapsed, and outputs the broadcast radio sound. According to this configuration, by inserting an arbitrary output instead of decompression, it is possible to suppress the sense of discomfort felt by the user due to decompression.

[0119] (Technology 7) The radio device according to technology 6, wherein the predetermined output section is a silent section or an announcement section including a predetermined voice message. According to this configuration, it is possible to adjust the switching timing using information that does not cause discomfort when outputting radio broadcasts.

[0120] (Technology 8) The radio communication system further includes an acquisition unit that acquires information about an antenna tower that transmits the radio signal of the broadcast radio broadcast and location information of the radio device, The prediction unit further deriving a distance from the antenna tower that results in an allowable propagation loss of the radio signal and an amount of change in the distance between the antenna tower and the radio device per unit time based on the information about the antenna tower and the location information; calculating a predicted reception time until the radio signal from the antenna tower goes out of a range in which it can be received, using the distance at which the propagation loss is acceptable and the amount of change in distance per unit time; The radio device according to Technology 1 or Technology 2 corrects the grace time predicted based on the time difference using the predicted reception time. This configuration allows for more accurate prediction of the grace period using information from the antenna tower and the device itself, making it possible to identify a more appropriate timing for switching from broadcast radio to IP radio.

[0121] (Technology 9) The radio device according to technology 8, wherein the prediction unit performs the correction by weighted addition of a grace period predicted based on the time difference and the predicted reception time. According to this configuration, the grace period can be corrected using a simple method.

[0122] (Technology 10) The radio device according to technology 8, wherein the prediction unit performs the correction based on the reliability of each of the grace time predicted based on the time difference and the predicted reception time. According to this configuration, by using the reliability corresponding to each prediction result, it is possible to further improve the accuracy of the grace period.

[0123] (Technology 11) a first receiving step of receiving a radio signal of a broadcast radio broadcast; a second receiving step of receiving a radio signal of the IP simulcast radio broadcast; a calculation step of calculating a time difference between the broadcast radio sound based on the radio signal acquired in the first receiving step and the IP radio sound based on the radio signal acquired in the second receiving step; a prediction step of predicting a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference; a calculation step of calculating an extension rate based on the grace time; a switching step of expanding the broadcast radio sound using the expansion rate and outputting the sound until the grace time has elapsed, and switching to the sound output of the IP radio sound when the grace time has elapsed; A method for controlling a radio device having the above configuration. This configuration can reduce the sense of discomfort felt by users when switching broadcasts in a car radio device, etc. In particular, it can minimize both the expansion rate of the audio output before switching and the time required to synchronize the switching timing.

[0124] (Technology 12) On the computer, a first receiving step of receiving a radio signal of a broadcast radio broadcast; a second receiving step of receiving a radio signal of the IP simulcast radio broadcast; a calculation step of calculating a time difference between the broadcast radio sound based on the radio signal acquired in the first receiving step and the IP radio sound based on the radio signal acquired in the second receiving step; a prediction step of predicting a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference; a calculation step of calculating an extension rate based on the grace time; a switching step of expanding the broadcast radio sound using the expansion rate and outputting the sound until the grace time has elapsed, and switching to the sound output of the IP radio sound when the grace time has elapsed; A program to execute. This configuration can reduce the sense of discomfort felt by users when switching broadcasts in a car radio device, etc. In particular, it can minimize both the expansion rate of the audio output before switching and the time required to synchronize the switching timing. [Industrial Applicability]

[0125] The present disclosure is useful as a radio device, a control method for a radio device, and a program. [Explanation of symbols]

[0126] 100...Radio equipment 101, 102...antennas 103...Broadcast radio receiver 104...IP radio receiver 105...Broadcast radio decoding section 106...IP radio decoding section 107...Time lag calculation unit 108...Delay time prediction unit 109...Extension / switching section 110...Audio output unit 801…Communications Department 802...Vehicle position information acquisition unit 803...Antenna location information database

Claims

1. a first receiving unit for receiving a radio signal of a broadcast radio broadcast; a second receiving unit that receives radio signals of IP simulcast radio broadcasts; a calculation unit that calculates a time difference between a broadcast radio sound based on the radio signal acquired by the first receiving unit and an IP radio sound based on the radio signal acquired by the second receiving unit; a prediction unit that predicts a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference; a calculation unit that calculates an extension rate based on the grace time; a switching unit that expands the broadcast radio sound using the expansion rate and outputs the sound until the grace time has elapsed, and switches to outputting the IP radio sound when the grace time has elapsed; A radio device having:

2. The radio device according to claim 1 , wherein the prediction unit predicts the grace period based on a change per unit time in a reception level of the radio signal of the broadcast radio broadcast and a predetermined reception level.

3. the broadcast radio transmission comprises a plurality of radio signals of the same content; the calculation unit calculates a time offset of the IP radio sound relative to each of the broadcast radio sounds based on the plurality of radio signals; The radio device of claim 1 , wherein the prediction unit predicts the grace period based on a time offset of the IP radio sound relative to each of the broadcast radio sounds based on the plurality of radio signals.

4. The radio device according to claim 1 , wherein the calculation unit sets the extension rate to 1 or a predetermined minimum extension rate when the grace period exceeds a predetermined threshold.

5. The radio device according to claim 1 , wherein, when the extension rate calculated based on the grace period exceeds a predetermined maximum extension rate, the calculation unit sets the extension rate to the predetermined maximum extension rate.

6. 2. The radio device according to claim 1, wherein, when the expansion rate calculated based on the grace period exceeds a predetermined maximum expansion rate, the switching unit inserts a predetermined output section into the broadcast radio sound before the grace period has elapsed, instead of expanding the broadcast radio sound at the expansion rate.

7. 7. The radio device according to claim 6, wherein the predetermined output section is a silent section or an announcement section including a predetermined voice message.

8. The radio communication system further includes an acquisition unit that acquires information about an antenna tower that transmits the radio signal of the broadcast radio broadcast and location information of the radio device, The prediction unit further deriving a distance from the antenna tower that results in an allowable propagation loss of the radio signal and an amount of change in the distance between the antenna tower and the radio device per unit time based on the information about the antenna tower and the location information; calculating a predicted reception time until the radio signal from the antenna tower goes out of a range in which it can be received, using the distance at which the propagation loss is acceptable and the amount of change in distance per unit time; The radio device according to claim 1 , wherein the grace period predicted based on the time difference is corrected using the predicted reception time.

9. The radio device according to claim 8 , wherein the prediction unit performs the correction by weighting and adding a grace time predicted based on the time difference and the predicted reception time.

10. The radio device according to claim 8 , wherein the prediction unit performs the correction based on the reliability of each of the grace time predicted based on the time difference and the predicted reception time.

11. a first receiving step of receiving a radio signal of a broadcast radio broadcast; a second receiving step of receiving a radio signal of the IP simulcast radio broadcast; a calculation step of calculating a time difference between the broadcast radio sound based on the radio signal acquired in the first receiving step and the IP radio sound based on the radio signal acquired in the second receiving step; a prediction step of predicting a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference; a calculation step of calculating an extension rate based on the grace time; a switching step of expanding the broadcast radio sound using the expansion rate until the grace time has elapsed and outputting the sound, and switching to outputting the IP radio sound when the grace time has elapsed; A method for controlling a radio device having the above configuration.

12. On the computer, a first receiving step of receiving a radio signal of a broadcast radio broadcast; a second receiving step of receiving a radio signal of the IP simulcast radio broadcast; a calculation step of calculating a time difference between the broadcast radio sound based on the radio signal acquired in the first receiving step and the IP radio sound based on the radio signal acquired in the second receiving step; a prediction step of predicting a grace period until switching from the broadcast radio sound to the IP radio sound based on the time difference; a calculation step of calculating an extension rate based on the grace time; a switching step of expanding the broadcast radio sound using the expansion rate until the grace time has elapsed and outputting the sound, and switching to outputting the IP radio sound when the grace time has elapsed; A program to execute.

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