Receiver, receiving method and program

Abstract

To prompt a user to take more appropriate measures when deterioration in reception quality is detected.SOLUTION: A broadcast receiving unit measures a first reception quality that is a reception quality of a data signal to be broadcast, and a second reception quality that is a reception quality of a signal other than the data signal, and when a quality difference which is a difference between the first reception quality and the second reception quality is larger than a predetermined quality difference threshold after a certain point in time, a control unit outputs notification information indicating the possibility of reception quality deterioration due to hierarchical division multiplexing of the data signal to a notification unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a receiver, a receiving method, and a program. [Background technology]

[0002] When receiving digital television broadcasts, reception interference can occur. Providing hints about the causes of reception interference and solutions to help viewers enjoy broadcast programs has been proposed. For example, the receiving device described in Patent Document 1 includes a television device main unit and a remote control device. The television device main unit includes an antenna, an analog modulation wave demodulation unit, a signal control unit, a system control unit, a digital modulation wave demodulation unit, a digital decoding processing unit, a graphic drawing multiplex display processing unit, an audio output processing unit, a speaker, an internal or external display device, a known defect display processing unit, and a user information storage unit. The known defect status storage unit stores known information about reception interference. The known information is stored, for example, as a table that associates channels with the details of the defects.

[0003] On the other hand, for advanced terrestrial broadcasting (sometimes simply referred to as "advanced broadcasting"), multiplexing multiple data signals using layered division multiplexing (LDM) is being considered. In advanced terrestrial broadcasting, in addition to a data signal (referred to herein as the "current signal") that provides video similar to that of current terrestrial digital broadcasting, a new data signal (referred to herein as the "advanced signal") that provides video with higher resolution is assigned to a lower signal level layer. A receiver (referred to herein as the "current device") that receives current terrestrial digital broadcasting (referred to herein as the "current broadcasting") cannot decode the advanced signal.

[0004] Current devices measure the reception quality of data signals transmitted by current broadcasting and monitor the measured reception quality. For example, the modulation error ratio (MER) is obtained as an index of reception quality. Some current devices calculate the signal-to-noise ratio (C / N) from the measured MER. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-72335 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a broadcast channel that transmits data signals using the LDM method is selected, the reception quality of the current signal included in the multiplexed data signal is expected to be worse than the current signal transmitted by current broadcasting without the LDM method. For example, some television broadcast receivers are equipped with demodulation chips. Some demodulation chips acquire the C / N ratio of the received signal based on signals other than pilot signals. These signals include data signals or control signals. However, with current devices, it is difficult to determine whether this degradation in reception quality is due to LDM. Furthermore, because users cannot identify the cause of the degradation in reception quality, they may take unnecessary measures. For example, users may suspect that the degradation in reception quality is due to reception interference, a defect in the broadcast service, or a defect in the receiver, and make unnecessary inquiries to broadcasters, receiver manufacturers, or distributors. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and one aspect of the present invention is a broadcast receiving unit that measures a first reception quality that is the reception quality of a broadcast data signal and a second reception quality that is the reception quality of a signal other than the data signal; A receiver comprising: a control unit that outputs notification information indicating the possibility of a decrease in reception quality due to hierarchical division multiplexing of the data signal to a notification unit when a quality difference, which is the difference between the first reception quality and the second reception quality, is larger than a predetermined quality difference threshold after a specific point in time. [Effects of the Invention]

[0008] According to the embodiment of the present invention, when deterioration of reception quality is detected, it is possible to prompt the user to take more appropriate measures. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic block diagram illustrating an example of the configuration of a receiving system according to a first embodiment. [Figure 2] 5 is a flowchart showing a first example of a channel search process according to the first embodiment. [Figure 3] 10 is a flowchart showing a first example of an output determination process according to the first embodiment. [Figure 4] FIG. 1 is an explanatory diagram illustrating multiplexing of broadcast signals based on the LDM method. [Figure 5] FIG. 2 is a diagram showing a first example of a first type display screen according to the first embodiment. [Figure 6] FIG. 10 is a diagram showing a second example of the first type display screen according to the first embodiment. [Figure 7] 10 is a flowchart showing a second example of the channel search process according to the first embodiment. [Figure 8] 10 is a flowchart showing a second example of the output determination process according to the first embodiment. [Figure 9] 10 is a flowchart showing a third example of the output determination process according to the first embodiment. [Figure 10]10 is a flowchart showing a fourth example of the output determination process according to the first embodiment. [Figure 11] 10 is a flowchart showing an example of a channel search process according to the second embodiment. [Figure 12] 10 is a flowchart showing a first example of an output determination process according to the second embodiment. [Figure 13] 10 is a flowchart showing a second example of the output determination process according to the second embodiment. [Figure 14] 10 is a flowchart showing a third example of the output determination process according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. When the configuration described in a particular embodiment, modification, or section is similar to the configuration described in another embodiment, modification, or section, the description of that embodiment may be used by reference and not repeated. Furthermore, components having the same function as components shown in each section are given the same reference numerals, and the description of that component may be used by reference unless otherwise specified.

[0011] First Embodiment Next, a description will be given of an example of the configuration of the receiving system 1 according to the first embodiment. Fig. 1 is a schematic block diagram showing an example of the configuration of the receiving system 1 according to this embodiment. The receiving system 1 includes an antenna unit 80 and a receiver 100. The following description mainly focuses on the case where the receiver 100 provides broadcasting services for current broadcasting, but does not provide broadcasting services for advanced broadcasting.

[0012] The antenna unit 80 receives broadcast waves sent from a broadcast station and includes an antenna 82 and a booster 84. The antenna 82 receives the electric signal generated by receiving the incoming broadcast wave as a broadcast signal. The antenna 82 is, for example, a parabolic antenna. The antenna 82 outputs the received broadcast signal to the booster 84. Booster 84 amplifies the intensity of the broadcast signal input from antenna 82 and outputs the amplified broadcast signal to receiver 100 .

[0013] The receiver 100 extracts a data signal from a broadcast signal input from the antenna unit 80, and presents the audio and video of the broadcast program as content transmitted by the extracted data signal. The receiver 100 measures a first reception quality, which is the reception quality of a broadcast data signal, and a second reception quality, which is the reception quality of a signal other than the data signal. The receiver 100 determines whether the quality difference between the first reception quality and the second reception quality is greater than a predetermined quality difference threshold after a specific point in time. Based on this state, the receiver 100 outputs notification information indicating the possibility of a degradation in reception quality due to LDM of the data signal.

[0014] The receiver 100 includes a main system unit 10, a transmission / reception module 40, an operation input unit 50, a speaker 60, and a display unit 70. The speaker 60 and the display unit 70 function as a notification unit 55 that notifies various types of information. The notified information includes, for example, notification information to notify the start of broadcasting using the advanced terrestrial LDM system.

[0015] The main system unit 10 separates a data signal and a pilot signal (reference signal) from the broadcast signal input from the antenna unit 80. The main system unit 10 separates a control signal and a content signal from the separated data signal. The control signal is a signal that carries various control information used in receiving and processing the broadcast signal. The content signal is a signal that carries the content. The main system unit 10 decodes an audio signal and a video signal that represent the audio that makes up the content. The main system unit 10 outputs the decoded audio signal to the speaker 60 and outputs the decoded video signal to the display unit 70.

[0016] The speaker 60 emits (plays) sound based on an audio signal input from the main system unit 10. The display unit 70 displays an image on a display surface based on a video signal input from the main system unit 10. The display unit 70 includes, for example, a display element and a drive circuit for driving the display element. The display element may be any type of display, such as a liquid crystal display, a plasma display, or an organic electroluminescence display.

[0017] The transmitting / receiving module 40 is connected to a communication network wirelessly or via a wired connection, and transmits and receives various data to and from devices connected to the communication network. The transmitting / receiving module 40 is connected to an in-house communication network that complies with standards such as IEEE802.11 and IEEE802.15.3. The transmitting / receiving module 40 connects to a destination device via the network and transmits and receives data to and from that device. The transmitting / receiving module 40 transmits transmission data input from the main system unit 10 to the destination device, and outputs received data received from the source device to the main system unit 10.

[0018] The operation input unit 50 acquires an operation signal based on a user's operation and outputs the acquired operation signal to the main system unit 10. The main system unit 10 controls its operation based on the operation signal input from the operation input unit 50. The operation signal instructs the execution or stop of a predetermined function, the broadcast channel, the setting of various information, the volume, the color, and the like. The operation input unit 50 may include a component for accepting an operation. Such a component may include, for example, a dedicated component such as a button, a dial, or a knob, or a general-purpose component such as a touch sensor or a mouse. The touch sensor may be integrated with the display and function as a touch panel. The operation input unit 50 may include a sensor for wirelessly receiving an operation signal from a remote controller (remote control). The sensor may be, for example, an infrared sensor or any other component capable of detecting electromagnetic waves carrying an operation signal.

[0019] The main system unit 10 includes a control unit 12 , a broadcast receiving unit 13 , an audio processing unit 20 , a display processing unit 24 , a storage unit 26 , a flash memory 28 , and a digital I / F 30 . The control unit 12 controls the processing of each unit of the receiver 100 and performs the functions of the receiver 100. The control unit 12 may be configured with dedicated hardware, or may be configured with a general-purpose computer system. The computer system includes at least an arithmetic processing unit and a storage medium. For example, a processor such as a CPU (Central Processing Unit) can be used as the arithmetic processing unit. The storage medium includes a storage unit 26 and a flash memory 28. The arithmetic processing unit reads a program stored in advance in the flash memory 28, and loads the read program into the storage unit 26. The arithmetic processing unit executes the program loaded into the storage unit 26 to realize the functions of the control unit 12. In this application, "executing a program" or "running a program" includes the meaning of executing processing instructed by instructions written in the program.

[0020] The control unit 12 may receive an operation signal from the operation input unit 50. The control unit 12 may execute processing using various information instructed by the operation signal. The control unit 12 may output an audio signal or a video signal acquired by the processing executed by the control unit 12 to the audio processing unit 20 or the display processing unit 24, respectively. The functions of the control unit 12 may be realized by executing a program acquired by software download. In software download, the program is carried on the broadcast wave as part of a data signal. The presence or absence of the program or the time when the program is transmitted may be notified, for example, using notification information multiplexed into the content signal. When the content signal of a broadcast program is multiplexed using the MMT-TLV (MPEG Media Transport-Length Value) format, the notification information may be transmitted using, for example, an MH-SDTT (Software Download Trigger Table) as an information element. The control unit 12 can extract the program from the data signal obtained at the time notified by the notification information.

[0021] In this embodiment, a multiplexed signal in which an existing signal and an advanced signal are multiplexed using the LDM method as a data signal may be transmitted, or an existing signal based on the existing method may be transmitted. As illustrated in FIG. 4, the multiplexed signal is configured by assigning the existing signal and the advanced signal to different output levels in a common frequency band. The existing signal is assigned to a high-power layer (UL: Upper Layer), and the advanced signal is assigned to a low-power layer (LL: Lower Level). The level difference between the high-power layer and the low-power layer is called the injection level (IL). IL can also be considered as the range of the output level of the high-power layer. The existing signal and the advanced signal are modulated using different modulation methods. Even if the current signal is successfully demodulated, the advanced signal cannot be demodulated and is therefore considered a noise component. The addition of noise components based on the advanced signal to environmental noise can degrade reception quality. In other words, the total noise amount is the linear sum of the environmental noise amount N and the output level LL of the low-power layer. When the amount of environmental noise N and the output level LL are each given in decibels, the C / N ratio of the current signal is given by equation (1). In equation (1), UL represents the decibel value indicating the output level of the high power tier. C / N=UL-10log(10(LL / 10)+10(N / 10))…(1)

[0022] Therefore, the control unit 12 determines whether the deterioration of reception quality is caused by LDM using the following method. More specifically, the control unit 12 determines whether a state has occurred in which the quality difference between the first reception quality and the second reception quality has become more significant than a predetermined quality difference threshold (referred to herein as a "quality difference threshold") since a certain point in time. The first reception quality refers to the reception quality of a data signal transmitted by the broadcast waves of the channel selected at that time (referred to herein as a "first broadcast channel" or "selected channel"). The second reception quality refers to the reception quality of a signal separate from the data signal. In this embodiment, the separate signal refers to a data signal transmitted by the broadcast waves of a broadcast channel separate from the selected channel (referred to herein as a "second broadcast channel" or "other channel"). The control unit 12 generates a display screen (referred to herein as a "first type display screen") showing the first type notification information based on the state, and outputs a video signal showing the generated display screen to the display processing unit 24. The display unit 70 presents the first type notification information based on the video signal input via the display processing unit 24.

[0023] The first type notification information is information indicating the possibility of degradation of reception quality due to LDM of the data signal transmitted on the first broadcast channel. The control unit 12 may determine whether or not a state has occurred in which the first reception quality is lower than a predetermined reception quality threshold (referred to as a "reception quality threshold" in this application). The control unit 12 may not output the first type notification information, and may output the second type notification information to the display processing unit 24 when the first reception quality is lower than the reception quality threshold. The display processing unit 24 generates a display screen (referred to as a "second type display screen" in this application) that displays the second type notification information input from the control unit 12, and outputs a video signal showing the generated display screen to the display processing unit 24. The display unit 70 presents the second type notification information based on the video signal input via the display processing unit 24. The second type notification information corresponds to a normal display of degradation of reception quality.

[0024] The timing when the control unit 12 executes the notification information output determination process is, for example, when a new broadcast channel is selected. The broadcast channel designated by an operation signal input from the operation input unit 50 can be selected as the first broadcast channel. Selection of a new broadcast channel includes not only a case where a broadcast channel currently being received is changed to another broadcast channel, but also a case where, after power supply is resumed, a receiving channel indicated by receiving channel information previously stored in the memory unit 26 before power was cut off is identified. The second broadcast channel is a broadcast channel whose reception quality has been measured by a channel search, excluding the first broadcast channel. Details of the channel search and output determination process will be described later.

[0025] The broadcast receiving unit 13 demodulates the data signal transmitted by the broadcast signal input from the antenna unit 80, and extracts the audio signal and video signal of the broadcast program from the demodulated data signal. The broadcast receiving unit 13 outputs the extracted audio signal and video signal to the audio processing unit 20 and the display processing unit 24, respectively. The broadcast receiving unit 13 includes a tuner unit 14, a demodulation unit 16, and a descrambling / demuxing unit 18.

[0026] The tuner unit 14 selects a broadcast channel designated by channel selection information input from the control unit 12 as the first broadcast channel of the broadcast signal input from the antenna unit 80. The channel selection information is designated by an operation signal input from the operation input unit 50. The tuner unit 14 down-converts the input broadcast signal based on a center frequency (broadcast frequency) corresponding to the selected broadcast channel, converting it into an intermediate frequency (IF) signal. The tuner unit 14 measures the strength of the input received signal as a received signal strength indicator (RSSI). The tuner unit 14 outputs the measured received signal strength to the control unit 12. Based on the measured received signal strength, the tuner unit 14 adjusts the amplitude of the IF signal so that the signal level falls within a predetermined range. The tuner unit 14 outputs the amplitude-adjusted IF signal to the demodulation unit 16.

[0027] The demodulator 16 demodulates the IF signal input from the tuner 14 using a predetermined demodulation method and converts it into a digital signal. The demodulator 16 performs error detection and error correction on the converted digital signal. The demodulator 16 uses a predetermined demodulation method corresponding to the modulation method used to modulate the digital signal to be broadcast. For example, a method corresponding to a modulation method such as 64QAM or 16QAM is used as the demodulation method. The demodulator 16 measures the reception quality of the input IF signal. The demodulator 16 measures, for example, the C / N (signal-to-noise ratio) and the bit error rate (BER) as indicators of reception quality. The demodulator 16 calculates, for example, a modulation error ratio (MER) from the demodulated signal using a known method. The modulation error ratio is an indicator of the degree of fluctuation of the values ​​of individual symbols representing the IF signal from a predetermined reference value. The demodulator 16 can convert the MER to the C / N using a known conversion formula. The C / N is an index indicating that the higher the value, the higher the reception quality. The BER is an index indicating the ratio of the number of bits containing errors to the total number of bits. In error detection, the demodulation unit 16 compares a calculated value obtained by performing a certain calculation process on each block that constitutes a part of the digital signal with an error detection code and determines whether the two match. When transmitting a data signal, the calculated value obtained by the calculation process on each block is added as an error detection code. The demodulation unit 16 detects a bit error when the two do not match, and can determine the BER based on the frequency at which the bit error is detected. The smaller the BER value, the higher the reception quality. The demodulation unit 16 outputs reception quality information indicating an index of the measured reception quality to the control unit 12.

[0028] In this embodiment, the demodulator 16 uses the demodulated data signal to measure reception quality. The demodulator 16 can identify a data region of the IF signal to which data symbols constituting the data signal are assigned and a pilot region to which symbols constituting the pilot signal are assigned. The pilot signal is a reference signal whose main purpose is to measure reception quality and is not intended to transmit information. The demodulator 16 can generate a data signal and a pilot signal by concatenating bits represented by symbols respectively assigned to the identified data region and pilot region. The symbol allocation may be indicated, for example, by a TMCC signal constituting a control signal. The data region includes a control region (e.g., a TMCC region) in which symbols constituting the control signal are carried, and other regions. Symbols constituting a content signal are assigned to other regions. The demodulator 16 can generate a control signal and a content signal by concatenating bits represented by symbols respectively assigned to the identified control region and other regions. The demodulator 16 outputs the generated content signal to the descrambling / demuxing unit 18.

[0029] The descrambling / demuxing unit 18 descrambles the content signal input from the demodulation unit 16. Descrambling is equivalent to descrambling. In descrambling, the bit sequence of the input content signal is rearranged in the reverse order of the scrambling performed on the bit sequence of the broadcast content signal. The descrambling / demuxing unit 18 separates the data signal obtained by descrambling into component signals such as audio signals and video signals by referring to the configuration information multiplexed onto the content signal (demultiplexing). When the MMT-TLV format is used to multiplex the content signal, the configuration information is described in the MPT (MMT Package Table). The descrambling / demuxing unit 18 outputs the extracted audio and video signals to the audio processing unit 20 and the display processing unit 24, respectively.

[0030] The audio processing unit 20 decodes the audio signal input from the descrambler / demuxer 18 using a predetermined audio decoding method. The predetermined audio decoding method may be a method corresponding to the audio encoding method (e.g., AAC: Advance Audio Coding, MPEG-4 AUDIO, etc.) used to encode the audio signal to be broadcast. The audio processing unit 20 outputs the decoded audio signal or the audio signal input from the control unit 12 to the speaker 60. When audio signals are input simultaneously from the control unit 12 and the descrambler / demuxer 18, the audio processing unit 20 may add (mix) the decoded audio signal and the audio signal input from the control unit 12 and output the audio signal obtained by the addition to the speaker 60.

[0031] The display processing unit 24 decodes the video signal input from the descrambler / demuxer 18 using a predetermined video decoding method. The predetermined video decoding method may be a method corresponding to the video encoding method (e.g., High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), etc.) used to encode the video signal to be broadcast. The display processing unit 24 outputs the decoded video signal or the video signal input from the control unit 12 to the display unit 70. When video signals are input from the control unit 12 and the descrambler / demuxer 18 simultaneously, the display processing unit 24 may superimpose the decoded video signal on the video signal input from the control unit 12 and output the superimposed video signal to the speaker 60.

[0032] The storage unit 26 is an example of a main memory that constitutes the computer system of the receiver 100. The storage unit 26 is, for example, a volatile memory such as a RAM (Random Access Memory). The storage unit 26 is mainly used as a work area for the control unit 12. That is, the control unit 12 reads a program and parameters that it is instructed to execute from the flash memory 28, and stores the read program and parameters in the storage unit 26. The control unit 12 temporarily stores intermediate values ​​obtained by executing a certain process in the storage unit 26, and the stored intermediate values ​​can be used when executing another process.

[0033] Flash memory 28 is an example of an auxiliary storage device that permanently stores various programs and various data. Setting information, parameters, and measurement data such as reception quality used in processing can be stored in flash memory 28. Receiver 100 may include, as an auxiliary storage device, an SSD (Solid Storage Device), an HDD (Hard Disk Drive), or the like instead of or in addition to flash memory 28.

[0034] The digital I / F (Interface) 30 inputs and outputs various types of data to and from the transceiver module 40. The digital I / F 30 outputs a transmission signal input from the control unit 12 to the transceiver module 40. The digital I / F 30 outputs a reception signal input from the transceiver module 40 to the control unit 12.

[0035] When receiver 100 is installed (used for the first time), it performs a channel search in response to a user's operation. During the channel search, receiver 100 detects a broadcast channel whose broadcast signal can be stably received in the reception environment where receiver 100 is installed, and registers broadcast channel information indicating the detected broadcast channel in the receiver itself.

[0036] In the configuration illustrated in Fig. 1, the control unit 12 of the main system unit 10 is instructed to start a channel search by an operation signal input from the operation input unit 50 in response to a user operation. At this time, the control unit 12 reads a control program from the storage unit 26, loads it into the flash memory 28, and starts executing it. The control unit 12 sets the frequency for each broadcast channel of terrestrial digital broadcasting to the tuner unit 14. The tuner unit 14 outputs an IF signal based on the broadcast signal carried at the set frequency to the demodulator unit 16. The control unit 12 acquires the received signal strength from the tuner unit 14 and determines whether or not there is a broadcast wave on the selected channel based on the acquired received signal strength.

[0037] The control unit 12 may determine whether the conditions for channel selection by this device are met based on control information indicated in the control signal obtained from the demodulation unit 16. The control unit 12 monitors reception quality information input from the demodulation unit 16 and determines whether stable reception is possible based on the reception quality information. The control unit 12 sequentially performs these processes for all broadcast channels assigned to terrestrial digital broadcasting. The control unit 12 counts the number of actual broadcast waves and the number of stable broadcast waves based on the presence or absence of broadcast waves for each broadcast channel and the reception quality information. The number of actual broadcast waves corresponds to the number of broadcast channels for which broadcast signals can be received. The number of stable broadcast waves corresponds to the number of broadcast channels that the user can select. The control unit 12 stores the information obtained by the channel search in the flash memory 28 as channel search information.

[0038] After installing receiver 100, control unit 12 periodically performs a channel search to check for the presence of new receivable broadcast waves. For example, control unit 12 may be configured to perform a channel search at a predetermined execution time. Control unit 12 may perform a channel search as background processing, regardless of whether the user is watching a broadcast program. For example, if broadcast receiving unit 13 has the capability to simultaneously process broadcast signals carried on multiple broadcast channels, control unit 12 may acquire reception quality information based on broadcast signals carried on channels other than the channel selected by the user.

[0039] Next, an example of the channel search process according to this embodiment will be described below. Fig. 2 is a flowchart showing a first example of the channel search process according to this embodiment. (Step S102) When the current time reaches a preset execution time, the control unit 12 starts a channel search process. In the channel search, the control unit 12 executes the following process for each broadcast channel. (Step S104) The demodulator 16 measures the C / N ratio from the data signal obtained by demodulating the IF signal input from the tuner 14. The demodulator 16 outputs reception quality information indicating the measured C / N ratio to the controller 12.

[0040] (Step S106) The control unit 12 compares the C / N measured in the current channel search indicated in the reception quality information obtained from the demodulation unit 16 with the C / N measured in the previous channel search for the broadcast channel included in the channel search information stored in the flash memory 28. The control unit 12 determines whether the amount of decrease (deterioration) from the previous C / N to the current C / N is greater than a predetermined threshold value for the amount of decrease. If it is determined to be greater (YES in step S106), the process proceeds to step S108. If it is determined not to be greater (NO in step S106), the control unit 12 changes the broadcast channel to be processed to an unprocessed broadcast channel and returns to step S104 (not shown). If there is no unprocessed broadcast channel, the process of FIG. 2 ends.

[0041] (Step S108) The control unit 12 stores the current C / N for the broadcast channel to be processed in the flash memory 28 in association with the previous C / N. (Step S110) The control unit 12 associates the current C / N with the current broadcast channel being processed and stores the current date and time as the current C / N acquisition date and time in flash memory 28. The information stored in steps S108 and S110 indicates the broadcast channel on which a significant drop in C / N occurred and the date and time of this occurrence, and constitutes part of the channel search information. The control unit 12 changes the broadcast channel to be processed to an unprocessed broadcast channel, and returns to step S104 (not shown). If there is no unprocessed broadcast channel, the process of FIG. 2 ends.

[0042] Next, an example of the output determination process according to this embodiment will be described. Fig. 3 is a flowchart showing a first example of the output determination process according to this embodiment. Fig. 3 shows an example in which a broadcast channel that provides 2K broadcasting using video with a resolution of 1920 x 1080 as the current broadcast is selected. The data signal basically includes a 2K signal that transmits the video as the current signal, and an advanced signal is not multiplexed based on the LDM method. The advanced signal may include a 4K signal that transmits video with a resolution of 3840 x 2160.

[0043] (Step S202) The control unit 12 identifies a broadcast channel designated by an operation signal input from the operation input unit 50, and outputs channel selection information indicating the identified broadcast channel to the tuner unit 14 (2K broadcast channel selection). (Step S204) The tuner unit 14 measures the reception strength of the IF signal selected for the broadcast channel specified by the channel selection information from the broadcast signal input from the antenna unit 80. The demodulator 16 demodulates the IF signal obtained from the tuner unit 14 and measures the BER and C / N of the data signal extracted from the IF signal as reception quality. The controller 12 obtains reception strength information indicating the measured reception strength from the tuner unit 14, and obtains reception quality information indicating the measured BER and C / N from the demodulator 16.

[0044] (Step S206) The control unit 12 determines whether the reception condition of the selected broadcast channel is good or bad based on the acquired reception quality information. In determining whether the reception condition is good or bad, the control unit 12 determines, for example, whether the BER indicated in the reception quality information is equal to or greater than the Shannon limit. The Shannon limit corresponds to the upper limit of the BER at which the original bit string can be restored by error correction. If the reception condition is determined to be poor (step S206 YES), the control unit 12 proceeds to the processing of step S208. If the reception condition is determined to be good (step S206 NO), the processing of FIG. 3 ends.

[0045] (Step S208) The control unit 12 determines whether the reception strength indicated in the acquired reception strength information is insufficient. The control unit 12 can determine whether the reception strength is insufficient based on whether the reception strength indicated in the reception strength information is lower than a predetermined lower limit of reception strength. If it is determined that the reception strength is not insufficient (step S208 NO), the control unit 12 proceeds to the processing of step S210. If it is determined that the reception strength is insufficient (step S208 YES), the control unit 12 proceeds to the processing of step S216.

[0046] (Step S210) The control unit 12 refers to the channel search information stored in the flash memory 28 and determines whether a decrease (deterioration) in C / N ratio greater than a predetermined threshold value has occurred for the selected channel, and whether, at the time when the decrease occurred, a decrease in C / N ratio greater than a predetermined threshold value has occurred for another channel that is a broadcast channel separate from the selected channel. This determines whether, after a certain point in time, a state has occurred in which the quality difference between the first reception quality for the selected channel and the second reception quality for the other channel becomes more significant than the quality difference threshold value.

[0047] More specifically, the control unit 12 determines, as a first condition, whether or not the channel search information indicates the previous C / N and the current C / N at that time in association with the C / N acquisition date and time for the selected channel. The control unit 12 determines, as a second condition, whether or not the channel search information indicates, among other channels separate from the selected channel, whether or not there is a broadcast channel for which the same C / N acquisition date and time as the C / N acquisition date and time specified for the selected channel are indicated and for which the previous C / N and the current C / N are indicated at that time. Depending on whether or not both the first condition and the second condition are satisfied, the control unit 12 can determine whether or not significant C / N degradation has occurred for the selected channel and whether or not significant C / N degradation has occurred for other channels.

[0048] If a large C / N drop occurs for the selected channel and a large C / N drop does not occur for other channels (step S210 YES), the control unit 12 proceeds to the process of step S212. If a large C / N drop does not occur for the selected channel or a large C / N drop occurs for other channels (step S210 NO), the control unit 12 proceeds to the process of step S216.

[0049] (Step S212) The control unit 12 determines whether it is within X days since a drop in C / N for the selected channel that is greater than a predetermined threshold value for the drop was detected. The time when the drop in C / N was detected is specified by the date and time when the C / N was acquired, which is described in the channel search information. X is a predetermined number of days (for example, 3 to 5 days). If it is determined that it is within X days (YES in step S212), the process proceeds to step S214. If it is determined that it is more than X days (NO in step S212), the process proceeds to step S216.

[0050] (Step S214) The control unit 12 generates a first type display screen showing first type notification information indicating the possibility of degradation of reception quality due to LDM, and outputs a video signal showing the generated first type display screen to the display unit 70 via the display processing unit 24. The display unit 70 presents the first type notification information indicating the possibility of degradation of reception quality due to LDM. (Step S216) The control unit 12 generates a second type display screen showing second type notification information indicating a normal display of reception quality degradation, and outputs a video signal showing the generated second type display screen to the display unit 70 via the display processing unit 24. The display unit 70 presents the second type notification information indicating a normal display of reception quality degradation.

[0051] Next, an example of a display screen according to this embodiment will be described. Fig. 5 is a diagram showing a first example of a first type display screen according to this embodiment. The first-class display screen shown in FIG. 5 may be displayed immediately after selecting a channel when watching a broadcast program. The first-class display screen includes reception status information for the selected channel, reception signal quality, and first-class notification information. The first-class notification information includes a message within a dashed frame that reads, "There is a possibility of reception interference due to the start of terrestrial advanced LDM broadcasting. Please check the website to see if terrestrial advanced LDM broadcasting has started in your area." Users who come across the first-class notification information can be made aware of the possibility of degradation in reception quality due to LDM and can be informed of the need to improve their reception environment. This can prevent unnecessary user correspondence with broadcasters providing broadcast services on the channel, and receiver manufacturers or sellers.

[0052] The first-type notification information may include location information of guidance information indicating the start of terrestrial advanced LDM broadcasting on the selected channel. Such location information may include a link to the address of a web server where the guidance information is stored (e.g., a URL (Uniform Resource Locator)). When detecting a press on a link, the control unit 12 may use the digital I / F 30 and the transceiver module 40 to request guidance information from a device specified by the URL and acquire the requested guidance information. In this application, the term "press" includes not only an actual "press" but also the input of an operation signal indicating a position within that area. The control unit 12 may generate a video signal showing a display screen including the guidance information and output the video signal to the display unit 70 via the display processing unit 24.

[0053] The display screen shown in Figure 5 displays "Terrestrial-15" as the selected channel. "Terrestrial-15" refers to channel 15 of terrestrial digital broadcasting. The reception status information includes a reception status level "E" and a description of the status, "Insufficient reception signal quality." The control unit 12 selects a reception status level corresponding to the measured reception signal quality from multiple preset reception status levels. The control unit 12 pre-sets different reception signal quality ranges and descriptions for each reception status level, and can identify a reception status level and description corresponding to a range within the measured reception signal quality. The display screen also includes a message indicating the user's confirmation of the reception status, such as "Please check that the antenna wire is not loose and that the antenna power setting is correct. If the problem persists, the outdoor antenna needs to be inspected. Consult your dealer or other authorized service provider for inspection." This prompts the user to improve their reception environment.

[0054] In Figure 5, the received signal quality is expressed using an approximate conversion value. For example, the approximate conversion value is equivalent to 2.6 times the C / N ratio expressed in decibels. The current approximate conversion value is shown as "10," and the maximum value measured in the past is shown as "60." The current value is displayed in a bar graph along with the recommended value range. The recommended value range is between 60 and 100, and is displayed as the "range for stable viewing." Because the current value is significantly lower than the recommended value range, the user is prompted to check their reception environment.

[0055] FIG. 6 is a diagram showing a second example of the first type display screen according to the present embodiment. The Type 1 display screen shown in Figure 6 shows the reception status of all broadcast channels, including terrestrial digital broadcasting and satellite broadcasting. The reception status information is displayed as one of the codes A to E, indicating the reception strength and reception status level for each broadcast channel. However, for terrestrial digital broadcasting (terrestrial digital), the past (MM / DD / YYYY) and current reception strength values ​​are shown. For satellite broadcasting (BS / CS antenna), the current reception quality and reception strength values ​​are shown. However, in the example of Figure 6, the first type notification information includes a message indicating the possibility of degradation of reception quality due to LDM for the currently selected channel. The selected broadcast station and selected channel are identified as "Broadcast Station B" and "U26", respectively.

[0056] If the receiver 100 has a recording function, the scheduled broadcast channel may be tuned in immediately before the scheduled recording start time. In this case, the user is not expected to view the screen of the display unit 70. Therefore, the control unit 12 may use the user notification function to notify the user of the first-type notification information. More specifically, the control unit 12 generates a video signal representing an icon indicating the presence of a message, outputs the video signal to the display unit 70 via the display processing unit 24, and displays the icon. The control unit 12 may continue to display the icon even after the recording end time. The icon may be configured to represent, for example, a stylized envelope, letter, or the like. When the control unit 12 detects that the icon has been pressed, it erases the display of the icon and outputs a video signal representing a first-type display screen including a message representing the first-type notification information to the display unit 70 via the display processing unit 24. At this time, the first notification screen including the message representing the first-type notification information is displayed on the display unit 70. Note that the second type notification screen may be a portion of the first type notification screen exemplified in FIGS. 5 and 6, from which the first type notification information has been removed.

[0057] Next, a first modified example of this embodiment will be described, focusing on the differences from Figures 2 and 3. The channel search process and output determination process according to this modified example use a BER value instead of a C / N value as an index of reception quality. Figure 7 is a flowchart showing a second example of the channel search process according to this embodiment. The process in Figure 7 includes steps S102, S124, S126, S128, and S130.

[0058] (Step S124) The demodulator 16 measures the BER from the data signal obtained by demodulating the IF signal input from the tuner 14. The demodulator 16 outputs, to the control unit 12, reception quality information indicating the measured BER. (Step S126) The control unit 12 compares the current BER indicated in the reception quality information acquired from the demodulation unit 16 with the previous BER for the broadcast channel included in the channel search information stored in the storage unit . The control unit 12 determines whether the increase (deterioration) from the previous BER to the current BER is greater than a predetermined threshold value for the increase amount. If it is determined to be greater (YES in step S126), the process proceeds to step S128. If it is determined not to be greater (NO in step S126), the control unit 12 changes the broadcast channel to be processed to an unprocessed broadcast channel and returns to step S124 (not shown). If there are no unprocessed broadcast channels, the process in FIG. 7 ends.

[0059] (Step S128) The control unit 12 stores the current BER for the broadcast channel to be processed in the flash memory 28 in association with the previous BER. (Step S130) The control unit 12 stores the current date and time in the flash memory 28 as the current BER acquisition date and time for the broadcast channel to be processed, in association with the current BER. The control unit 12 changes the broadcast channel to be processed to an unprocessed broadcast channel, and returns to step S124 (not shown). If there is no unprocessed broadcast channel, the process of FIG. 2 ends.

[0060] 8 is a flowchart showing a second example of the output determination process according to this embodiment. The process in FIG. 8 includes steps S202, S224, S206, S208, S230, S232, S214, and S216. (Step S224) The tuner unit 14 measures the reception strength of the IF signal selected from the broadcast channel specified by the channel selection information from the broadcast signal input from the antenna unit 80. The demodulator 16 demodulates the IF signal obtained from the tuner unit 14 and measures the BER of the data signal extracted from the IF signal as reception quality. The controller 12 obtains reception strength information indicating the measured reception strength from the tuner unit 14, and obtains reception quality information indicating the measured BER from the demodulator 16. In this step, the C / N does not have to be measured.

[0061] (Step S230) The control unit 12 refers to the channel search information stored in the flash memory 28 and determines whether the increase (deterioration) in BER for the selected channel is greater than a predetermined increase threshold, and whether the increase in BER for other channels different from the selected channel is greater than a predetermined increase threshold. The BER-based determination in this step can be performed using a method similar to the C / N-based determination in step S210. If the control unit 12 determines that both the first and second conditions are satisfied (YES in step S230), the control unit 12 proceeds to processing in step S232. If the control unit 12 determines that either or both of the first and second conditions are not satisfied (NO in step S230), the control unit 12 proceeds to processing in step S216.

[0062] (Step S232) The control unit 12 determines whether or not it has been within X days since the time when an increase in BER larger than a predetermined increase width was detected for the selected channel. If it is determined that it is within X days (YES in step S232), the control unit 12 proceeds to the processing of step S214. If it is determined that it is more than X days (NO in step S232), the control unit 12 proceeds to the processing of step S216.

[0063] Next, a second modified example of this embodiment will be described, focusing mainly on the differences from Fig. 3. In the following description, an example will be taken where the C / N value is used as an index of reception quality. 9 is a flowchart showing a third example of the output determination process according to this embodiment. The process in FIG. 9 includes steps S202, S204, S206, S208, S210, S242, S212, S214, and S216. In this modification, when it is determined in step S210 that a large C / N drop has occurred for the selected channel and that a large C / N drop has not occurred for other channels (YES in step S210), the process proceeds to step S242.

[0064] (Step S242) The control unit 12 refers to the channel search information stored in the flash memory 28 and determines whether a state in which a drop in C / N for the selected channel that is greater than a predetermined threshold for the amount of drop has occurred, and at the time when the drop occurred, a drop in C / N for a channel other than the selected channel that is greater than the predetermined threshold for the amount of drop has not occurred, has occurred Y or more consecutive times up to that point. Y is a predetermined integer of 2 or greater (e.g., 3 to 5). If this state has occurred Y or more consecutive times (YES in step S242), the control unit 12 proceeds to the processing of step S212. If this state has not occurred Y or more consecutive times (NO in step S242), the control unit 12 proceeds to the processing of step S216.

[0065] A state in which a decrease in C / N ratio greater than a predetermined threshold value occurs for a selected channel, and at the time when the decrease occurs, a decrease in C / N ratio greater than a predetermined threshold value does not occur for other channels separate from the selected channel can be determined using a method similar to step S210. However, in this modification, when it is determined in step S106 that the amount of decrease in the current C / N is greater than a predetermined threshold value for the amount of decrease, the control unit 12 may use the previous C / N used in the determination in the processing of step S106 for the next channel search. As a result, an event in which the C / N decreases repeatedly is detected in step S242.

[0066] In step S106, the control unit 12 may determine whether the increase from the previous C / N to the current C / N is greater than a predetermined threshold value. If the control unit 12 determines that the increase is not large, it increments the number of channel searches performed since it determined that the decrease from the previous C / N to the current C / N was greater than the predetermined threshold value. The control unit 12 then associates the number of searches obtained by the increment with the broadcast channel and records it in the flash memory 28 as part of the channel search information. If the control unit 12 determines that the increase is large, it may clear the recorded number of channel searches to 0 (zero). The channel search information records, for each broadcast channel, whether a decrease in C / N greater than the predetermined threshold value has occurred up to that point, and, if so, the number of repetitions up to that point.

[0067] Therefore, in step S242, the control unit 12 refers to the channel search information and can determine whether there is an event in which a decrease in C / N greater than a predetermined threshold value has occurred in the selected channel up to that point, and then the C / N has not recovered, and a decrease in C / N greater than a predetermined threshold value has not occurred in other channels.

[0068] Next, a third modified example of this embodiment will be described, focusing mainly on the differences from Fig. 3. In the following description, an example will be taken where C / N is used as an index of reception quality. 10 is a flowchart showing a fourth example of the output determination process according to this embodiment. The process in FIG. 10 includes steps S202, S204, S206, S208, S210, S212, S252, S214, and S216. In this modified example, when it is determined in step S212 that the period will exceed X days (step S212 NO), the process proceeds to step S252.

[0069] (Step S252) The control unit 12 determines whether the period from the start of presentation of the first type notification information indicating the possibility of degradation of reception quality due to LDM to that point in time is within Z days. Z indicates a predetermined number of days (for example, 3 to 7 days). If it is determined to be within Z days (step S252 YES), the control unit 12 proceeds to the processing of step S214. If it is determined to be more than Z days (step S252 NO), the control unit 12 proceeds to the processing of step S216.

[0070] In addition, in step S252, in order to determine the period from the start of presentation of the first type notification information to that point, in step S214, the control unit 12 stores in flash memory 28 presentation record information indicating the date and time when the video signal showing the first type display screen was output to the display unit 70 and the selected channel.

[0071] This modification may be realized in combination with modification 2. For example, the process of Fig. 10 further includes the process of step S242, and in step S210, the control unit 12 may proceed to the process of step S242 when a large decrease in C / N has occurred for the selected channel and a large decrease in C / N has not occurred for other channels (YES in step S210).

[0072] In step S242, if a decrease in C / N for the selected channel that is greater than a predetermined threshold value for the decrease occurs, and if, at the time when the decrease occurs, a decrease in C / N for other channels different from the selected channel that is greater than a predetermined threshold value for the decrease does not occur, this state has occurred Y or more consecutive times up to that point (step S242 YES), proceed to processing in step S212.

[0073] In the second and third modifications, BER may be used as an index of reception quality instead of C / N. In that case, an increase in BER may be applied instead of a decrease in C / N in the processes of Figures 9 and 10. Furthermore, the process exemplified in Figure 7 may be executed as the channel search process.

[0074] <Second embodiment> Next, the present embodiment will be described, focusing on the differences from the first embodiment. In the following description, unless otherwise specified, the description of the first embodiment will be used for matters common to the first embodiment. The receiving system 1 according to this embodiment has the same functional configuration as the receiving system 1 according to the first embodiment.

[0075] The control unit 12 according to this embodiment detects a state in which a quality difference, which is the difference between a first reception quality of a data signal broadcast on a selected channel and a second reception quality of a pilot signal transmitted on the selected channel, becomes more significant than a predetermined quality difference threshold after a specific point in time. Based on this state, the control unit 12 outputs first-type notification information indicating the possibility of a decrease in reception quality due to hierarchical division multiplexing of the data signal to the notification unit 55. The quality difference occurs because a pilot signal is not multiplexed in the pilot region, even when the data signal allocated to the data region is configured by multiplexing an advanced signal onto a current signal in a lower-power layer with a lower output level.

[0076] Next, an example of channel search processing according to this embodiment will be described. Fig. 11 is a flowchart showing an example of channel search processing according to this embodiment. The processing in Fig. 11 includes steps S102, S144, S146, S148, and S150. Also, a case will be taken as an example in which the BER of a data signal obtained by demodulating symbols allocated to a data region (data segment) of an IF signal by the demodulator 16 and the CN of a pilot signal obtained by demodulating symbols allocated to a pilot region (pilot channel) are measured as indicators of reception quality.

[0077] (Step S144) The demodulator 16 measures the BER (hereinafter referred to as BERd) from the data signal obtained by demodulating the IF signal input from the tuner 14 and the C / N (hereinafter referred to as CNp) from the pilot signal. The demodulator 16 outputs reception quality information indicating the measured BERd and CNp to the controller 12. (Step S146) The control unit 12 compares the current BERd indicated in the reception quality information acquired from the demodulation unit 16 with the previous BERd for the broadcast channel included in the channel search information stored in the storage unit . The control unit 12 determines whether the increase from the previous BERd to the current BERd is greater than a predetermined threshold value for the increase amount. If it is determined to be greater (YES in step S146), the process proceeds to step S148. If it is determined not to be greater (NO in step S146), the broadcast channel to be processed is changed to an unprocessed broadcast channel, and the process returns to step S144 (not shown). If there are no unprocessed broadcast channels, the process of FIG. 11 ends.

[0078] (Step S148) The control unit 12 stores the current BERd and CNp in the flash memory 28 in association with the previous BERd and CNp for the broadcast channel to be processed. (Step S150) The control unit 12 associates the current CNp and BERd for the broadcast channel being processed and stores the current date and time as the current CN and BER acquisition date and time in the flash memory 28. The information on the previous BERd and CNp, current BERd and CNp, current CN and BER acquisition date and time stored in the flash memory 28 in steps S148 and S150 becomes part of the channel search information. The control unit 12 changes the broadcast channel to be processed to an unprocessed broadcast channel, and returns to step S144 (not shown). If there is no unprocessed broadcast channel, the process of FIG. 11 ends.

[0079] Next, an example of the output determination process according to this embodiment will be described. Fig. 12 is a flowchart showing a first example of the output determination process according to this embodiment. The process in Fig. 12 includes steps S202, S262, S264, S266, S270, S272, S274, S276, S214, and S216.

[0080] (Step S262) The demodulator 16 measures, as an index of reception quality, the CNp of a pilot signal obtained by demodulating the IF signal input from the tuner 14. The controller 12 acquires, from the demodulator 16, reception quality information indicating the CNp of the pilot signal. (Step S264) The control unit 12 determines the BERd of the data signal corresponding to the acquired CNp as BERd_p based on a preset correspondence relationship between the CNp of the pilot signal and the BERd of the data signal. The correspondence relationship between CNp and BERd may be given in any form, such as a mathematical formula or a mathematical table showing its theoretical characteristics. This correspondence relationship also depends on the modulation method. Therefore, the control unit 12 is set in advance with a correspondence relationship for each modification method. The control unit 12 uses the correspondence relationship corresponding to the modulation method used to modulate the pilot signal.

[0081] (Step S266) The demodulator 16 measures, as an index of reception quality, the BERd_d of the data signal obtained by demodulating the symbols assigned to the data region (data segment) of the IF signal input from the tuner 14. The controller 12 acquires reception quality information indicating the BERd_d of the data signal from the demodulator 16. (Step S270) The control unit 12 calculates a BER ratio Rber as an index of the magnitude of the difference between the BERd_d of the data signal and the BERd_p of the pilot signal. The BER ratio Rber corresponds to the ratio BERd_d / BERd_p of the BERd_d of the data signal to the BERd_p of the pilot signal.

[0082] (Step S272) The control unit 12 stores the current date and time and the BER ratio Rber for the selected channel in the flash memory 28 in association with each other. The control unit 12 may execute the processes of steps S226, S270, and S272 based on the CNp of the pilot signal and the BERd of the data signal obtained for each broadcast channel by the channel search to calculate the BER ratio Rber and store it in advance in the channel search information. In calculating the BER ratio Rber, the control unit 12 regards the BERd of the data signal as BERd_d.

[0083] (Step S274) The control unit 12 determines whether the difference in BER, which indicates the quality difference between the data signal and the pilot signal, is significant based on the BER ratio Rber at that time. A significant difference means that there is a significant difference. The control unit 12 can determine whether the quality difference is significant based on whether the BER ratio Rber is greater than a predetermined ratio threshold R. When LDM is not performed, the BERd_d of the data signal and the BERp_d of the pilot signal are approximately equal. In that case, the BER ratio Rber is approximately 1. However, when LDM is performed, the lower layer signals are not decoded and are considered to be noise components along with environmental noise. Since the BERd_d of the data signal increases, the control unit 12 sets a real value significantly greater than 1 as the BER ratio Rber. The control unit 12 can determine whether the quality difference is significant based on whether the BER ratio Rber is greater than a predetermined BER ratio threshold R. If it is determined that the quality difference is significant (YES in step S274), the control unit 12 proceeds to the processing of step S276. If it is determined that the difference is not significant (step S274 NO), the processing of FIG. 12 ends.

[0084] (Step S276) The control unit 12 determines whether the period up to that point in time during which a difference in BER indicating a significant difference in quality between the data signal and the pilot signal has occurred is within X days. For example, the control unit 12 references the channel search information and determines whether a significant difference in quality between the data signal and the pilot signal has occurred for each acquisition date and time for the selected channel based on the BER ratio Rber derived from CNp and BERd and the threshold R. The control unit 12 identifies the earliest date and time of acquisition of CNp and BERd that have caused the significant difference in quality to be detected consecutively up to that point in time as the occurrence date and time. The control unit 12 can determine the period from the identified occurrence date and time to that point in time as the period during which a significant difference in quality has occurred. If it is determined that the period is within X days (YES in step S276), the control unit 12 proceeds to the processing of step S214. If it is determined that the period is longer than X days (NO in step S276), the control unit 12 proceeds to the processing of step S216.

[0085] Next, a first modified example of this embodiment will be described, focusing mainly on the differences from FIG. 13 is a flowchart showing a second example of the output determination process according to this embodiment. The process in FIG. 13 includes steps S202, S262, S264, S266, S270, S272, S274, S282, S276, S214, and S216. In this modification, when it is determined in step S274 that the difference in quality between the data signal and the pilot signal is significant (YES in step S274), the control unit 12 proceeds to the process of step S282.

[0086] (Step S282) The control unit 12 determines whether a difference in BER indicating a significant difference in quality between the data signal and the pilot signal has occurred Y or more times in succession since the specific date up to that point. The control unit 12 determines the date to which the occurrence date and time identified in step S276 belongs as the specific date. For example, the control unit 12 can refer to the channel search information and determine whether a state in which a significant quality difference has been determined based on the BER ratio Rber derived from CNp and BERd and the threshold R for each acquisition date and time has occurred Y or more times in succession. If it is determined that a difference has occurred Y or more times in succession (step S282 YES), the control unit 12 proceeds to the processing of step S276. If it is determined that a difference has not occurred Y or more times in succession (step S282 NO), the control unit 12 proceeds to the processing of step S216.

[0087] Next, a second modification of this embodiment will be described, focusing mainly on the differences from FIG. 14 is a flowchart showing a third example of the output determination process according to this embodiment. The process in FIG. 14 includes steps S202, S262, S264, S266, S270, S272, S274, S276, S252, S214, and S216. In this modification, if it is determined in step S276 that the period during which the BER difference has occurred exceeds X days (step S276 NO), the process proceeds to step S252.

[0088] In the above description, an example was given in which BER was used as the index of the first reception quality of the data signal broadcast on the selected channel and the index of the second reception quality of the pilot signal, but this is not limiting. Instead of or in addition to BER, other types of indexes, such as CN and MER, may be used. In the above description, an example was given in which BERd_p is converted from CNp of the pilot signal, but the first reception quality index and the second reception quality index may be calculated directly from the data signal and the pilot signal, respectively. Furthermore, an example was given in which the ratio of the first reception quality index to the second reception quality index was used as the index of the quality difference, but this is not limiting. For example, the difference may be used instead of the ratio.

[0089] As described above, the receiver 100 according to this embodiment includes a broadcast receiving unit 13 that measures a first reception quality, which is the reception quality of a broadcast data signal, and a second reception quality, which is the reception quality of a signal other than the data signal. The receiver 100 also includes a control unit 12 that outputs first type notification information, which indicates the possibility of a degradation in reception quality due to LDM of the data signal, to a notification unit 55, based on a state in which the quality difference between the first reception quality and the second reception quality becomes more significant than a predetermined threshold value for quality difference after a specific point in time (for example, when the quality difference is greater than a predetermined threshold value for quality difference). According to this configuration, degradation of reception quality due to LDM is estimated based on the quality difference between a first reception quality of the data signal and a second reception quality of another signal received in parallel. The output first-type notification information notifies the user of the possibility that degradation of the reception quality of the data signal is due to LDM. Therefore, the user of the receiver 100 can know that the cause of degradation of reception quality is relatively unlikely to be a defect in the broadcast service or the receiver. Because unnecessary inquiries assuming a defect in the broadcast service or the receiver are reduced or eliminated, the burden of user support on the broadcaster, manufacturer, or seller of the receiver 100 is reduced or eliminated. Furthermore, the user of the receiver 100 can be encouraged to take effective measures to address degradation of reception quality, such as inspecting or replacing the antenna, or purchasing a receiver compatible with advanced broadcasting.

[0090] The broadcast receiving unit 13 may measure, as the second reception quality, the reception quality of a data signal transmitted on a second channel (e.g., another channel) that is a broadcast channel other than the first channel (e.g., the selected channel) that transmits the data signal. The control unit 12 may determine that the quality difference is more significant than the predetermined threshold for quality difference when the degree of deterioration (e.g., the amount of decrease in CN or the amount of increase in BER) of the measurement value of the first reception quality from the past measurement value is greater than a predetermined threshold for deterioration and the degree of deterioration of the measurement value of the second reception quality from the past measurement value is equal to or less than the threshold for deterioration. This configuration allows the degree of degradation in the reception quality of data signals between different channels to be compared, making it possible to distinguish between degradation in reception quality specific to the first channel and degradation in reception quality that occurs regardless of the channel, thereby enabling more reliable estimation of degradation in reception quality caused by LDM.

[0091] The broadcast receiving unit 13 may measure, as the second reception quality, the reception quality of a pilot signal transmitted over a broadcast channel that transmits a data signal. According to this configuration, the reception quality is compared between a data signal that is the target of LDM and a pilot signal that is not the target of LDM, so that degradation of reception quality caused by LDM can be estimated more reliably.

[0092] The broadcast receiving unit 13 may measure the C / N ratio as an index of reception quality. This quantifies the degree of noise components relative to the data signal.

[0093] The broadcast receiving unit 13 may measure the BER as an index of reception quality. This quantifies the degree of bit error in the data signal.

[0094] The control unit 12 may output the first type notification information when a state in which there is a significant quality difference between the first reception quality and the second reception quality is repeatedly detected a predetermined number of times or more. According to this configuration, when the quality difference between the first reception quality and the second reception quality repeatedly becomes more significant than a predetermined threshold value for the quality difference depending on the content to be transmitted and the reception environment, the first type notification information is output. Therefore, it is possible to avoid erroneous notification of a decrease in reception quality caused by LDM due to the quality difference accidentally becoming significant.

[0095] The control unit 12 outputs the first type notification information when a state in which there is a significant quality difference between the first reception quality and the second reception quality is detected within a predetermined period from the start of detection of the state in which there is a significant quality difference, or within a predetermined period from the first output of the first type notification information. According to this configuration, the notification is stopped after a sufficient period of time has passed for the user to recognize the possibility of a degradation in reception quality due to LDM, thereby reducing or eliminating the annoyance felt by the user by the notification.

[0096] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configurations are not limited to the above-described embodiments and modifications, and include designs that do not deviate from the gist of the present invention. The configurations described in the above-described embodiments can be combined in any manner.

[0097] The above description exemplifies a case in which the receiver 100 provides broadcast services based on current broadcasting but not on advanced broadcasting. However, this is not limiting. The receiver 100 may also have a function for providing broadcast services based on advanced broadcasting. In this case, the broadcast receiving unit 13 modulates the demodulated IF signal using the modulation method used for the modulation. The broadcast receiving unit 13 subtracts the IF signal assigned to the high-power hierarchical layer reconstructed by the modulation from the IF signal input from the antenna unit 80, and extracts the IF signal assigned to the low-power hierarchical layer. The broadcast receiving unit 13 demodulates the advanced broadcasting data signal assigned to the extracted IF signal using a demodulation method corresponding to the modulation method used for the modulation. When advanced broadcasting is selected in response to a user operation, the broadcast receiving unit 13 may cause the notification unit 55 to present content for the advanced broadcasting based on a content signal separated from the demodulated data signal. When current broadcasting is selected in response to a user operation, the broadcast receiving unit 13 causes the notification unit 55 to present first-type notification information according to the above method.

[0098] In the above description, an example was given in which a current signal and an advanced signal are assigned to the high-power hierarchical layer and the low-power hierarchical layer, respectively, but this is not limiting. It is sufficient if a signal of broadcast program content that provides video with a lower resolution than the low-power hierarchical layer is assigned to the high-power hierarchical layer. For example, a 1K signal and a 2K signal may be assigned to the high-power hierarchical layer and a 1K signal and a 4K signal may be assigned to the low-power hierarchical layer, respectively. The 1K signal is a broadcast signal used in existing high-definition television (HDTV) broadcasting services.

[0099] Additionally, an additional signal used for a supplementary service to the broadcast service provided in the high-power layer may be assigned to the low-power layer. In this case, the broadcast receiving unit 13 does not discard the high-power layer signal from the data signal, but instead employs both the high-power layer signal and the additional signal for use in presenting the content. For example, if a 2K signal is employed as the high-power layer signal, a differential signal between the 4K signal and the 2K signal may be assigned to the low-power layer signal as an additional signal. The broadcast receiving unit 13 synthesizes a 4K signal from the extracted 2K signal and differential signal, and decodes the synthesized 4K signal to enable the presentation of 4K broadcast content.

[0100] Furthermore, some components of the receiver 100 may be omitted, or other components may be added. For example, in the receiver 100, any one or a combination of the transceiver module 40, operation input unit 50, speaker 60, and display unit 70 may not necessarily be provided integrally in the receiver 100, as long as they can be connected to the main system unit 10 so as to be able to input and output various data. For example, in a receiver 100 configured as a dedicated television receiver, the transceiver module 40 may be omitted. In a receiver 100 configured as a set-top box or a recorder, the display unit 70 may be omitted. The receiver 100 may be provided with an antenna unit 80 and configured integrally.

[0101] Alternatively, a program for implementing some of the functions of the receiver 100 described above, such as some or all of the functions of the control unit 12, may be recorded on a computer-readable recording medium (e.g., flash memory 28), and the program recorded on the recording medium may be loaded into a computer system and executed to implement those functions. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer system" may also include multiple computer devices connected via a network, including communication lines such as the Internet, a WAN, a LAN, and a dedicated line. [Explanation of symbols]

[0102] 1...receiving system, 10...main system section, 12...control section, 13...broadcast receiving section, 14...tuner section, 16...demodulation section, 18...descrambling / demux section, 20...audio processing section, 24...display processing section, 26...storage section, 28...flash memory, 30...digital I / F, 40...transmission / reception module, 50...operation input section, 55...notification section, 60...speaker, 70...display section, 80...antenna section, 82...antenna, 84...booster, 100...receiver

Claims

1. a broadcast receiving unit that measures a first reception quality, which is the reception quality of a broadcast data signal, and a second reception quality, which is the reception quality of a signal other than the data signal; a control unit that outputs notification information indicating a possibility of a decrease in reception quality due to hierarchical division multiplexing of the data signal to a notification unit when a quality difference between the first reception quality and the second reception quality is larger than a predetermined quality difference threshold after a specific point in time. Receiver.

2. The broadcast receiving unit measuring, as the second reception quality, a reception quality of a data signal transmitted on a second channel, which is a broadcast channel other than the first channel transmitting the data signal, as the other signal; The control unit When the degree of deterioration of the first reception quality measurement value from a past measurement value is greater than a predetermined threshold of the degree of deterioration and the degree of deterioration of the second reception quality measurement value from a past measurement value is equal to or less than the threshold of the degree of deterioration, it is determined that the quality difference is greater than the predetermined threshold of the quality difference.

2. The receiver of claim 1.

3. The broadcast receiving unit measures, as the second reception quality, a reception quality of a pilot signal transmitted through a broadcast channel that transmits the data signal.

2. The receiver of claim 1.

4. The broadcast receiving unit measures a signal-to-noise ratio as an index of the reception quality.

4. The receiver according to claim 2 or claim 3.

5. The broadcast receiving unit measures a bit error rate as an index of the reception quality.

4. The receiver according to claim 2 or claim 3.

6. The control unit When a state in which the quality difference is greater than the quality difference threshold is repeatedly detected a predetermined number of times or more, the notification information is output.

2. The receiver of claim 1.

7. The control unit When a state in which the quality difference is greater than the quality difference threshold is detected within a predetermined period from the start of detection of the state in which the quality difference is greater than the quality difference threshold, or within a predetermined period from the first output of the notification information, the notification information is output.

2. The receiver of claim 1.

8. To the computer A program for causing the receiver according to claim 1 to function.

9. A receiving method in a receiver, comprising: The receiver, a first step of measuring a first reception quality, which is the reception quality of a broadcast data signal, and a second reception quality, which is the reception quality of a signal other than the data signal; a second step of outputting notification information indicating a possibility of a decrease in reception quality due to hierarchical division multiplexing of the data signal to a notification unit when a quality difference between the first reception quality and the second reception quality is larger than a predetermined quality difference threshold value after a specific time point. Receiving method.

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