KR102592655B1 - Multimedia device and method thereof - Google Patents

Abstract

A method of controlling a multimedia device according to an embodiment of the present invention includes the steps of selecting a specific channel at a first time, and a noise signal received from the specific channel is initially set to a preset channel impulse response (CIR) threshold. determining whether the error is abnormal, changing the initially preset CIR threshold to a new CIR threshold based on information about the number of errors in the forward error correction (FEC) block, and determining a new CIR threshold for the specific channel. It includes storing a CIR threshold in a memory, and when the specific channel is reselected at a second time, demodulating a signal received from the specific channel according to the CIR threshold stored in the memory. .

Description

Multimedia device and its control method {MULTIMEDIA DEVICE AND METHOD THEREOF}

The technical field of the present invention is to use various multimedia devices (e.g., televisions, mobile phones, tablet personal computers, laptops, wearable devices, etc.) that process broadcast signals. It is about. More specifically, for example, it can be applied to a broadcasting environment based on the ATSC (Advanced Television Systems Committee) 3.0 standard. However, it is not limited to this.

Recently, the ATSC 3.0 standard or the ISDB-S3 standard has been introduced as a next-generation broadcast standard. In particular, in the United States and elsewhere, the Federal Communications Commission (FFC) approved the use of ATSC 3.0 in November 2017, and accordingly, the Consumer Technology Association (CTA) and the National Association of Broadcasters (NAB) have been jointly operating in Cleveland and other countries since November 2017. Field testing has begun. And, as of 2021, we are building a broadcasting infrastructure that will allow more than 75% of viewers in about 62 DMAs (Designated Market Areas) to receive ATSC 3.0 broadcasts.

ATSC 3.0 service, for example, refers to a new type of integrated broadcasting service that combines terrestrial broadcasting services and Internet services. It is also called hybrid broadcasting, which provides various additional broadcasting services in a broadcasting and communication convergence environment that combines terrestrial broadcasting networks and broadband communication networks.

However, conventional multimedia devices (e.g., TVs capable of processing ATSC 3.0 hybrid broadcasting services, etc.) use a fixed CIR (Channel Impulse Response) threshold derived during the product (multimedia device, TV, etc.) manufacturing process. The on/off of the EQ block was determined using only (threshold).

According to this prior art, there was a problem in that it could not take into account all the various signal environments. For example, especially in the ATSC 3.0 broadcasting environment, there are cases where IP data is additionally received through Wi-Fi, etc., and there are cases where the signal environment varies significantly for each channel.

Accordingly, there was a problem in that the TV settings were incorrect, causing the image to be broken, the audio to be broken, or a skip phenomenon to occur during channel tuning. Here, the skip phenomenon means, for example, an error in which a broadcast signal is moved to the next channel even though there is a broadcast signal on channel 10.

One embodiment of the present invention seeks to propose a process for normally outputting video and audio even in poor signal conditions by adjusting settings to suit the signal of the corresponding channel in an RF (Radio Frequency) signal environment.

Another embodiment of the present invention stores the newly set CIR threshold value of each channel in memory (e.g., non-volatile memory or eMMC (Embedded Multi-Media Controller), etc.), thereby enabling channel switching with just one initial setting. We want to improve speed.

A method of controlling a multimedia device according to an embodiment of the present invention includes the steps of selecting a specific channel at a first time, and the noise signal received from the specific channel is initially set to a preset channel impulse response (CIR) threshold. determining whether the error is abnormal, changing the initially preset CIR threshold to a new CIR threshold based on information about the number of errors in the forward error correction (FEC) block, and determining a new CIR threshold for the specific channel. It includes storing a CIR threshold in a memory, and when the specific channel is reselected at a second time, demodulating a signal received from the specific channel according to the CIR threshold stored in the memory. .

For example, the memory is characterized by mapping and storing CIR threshold values for each channel.

The determining step includes, for example, if the noise signal is greater than the CIR threshold, turning on a filter for channel equalization, and if the noise signal is less than the CIR threshold, the channel It is designed to further include a step of turning off the filter for equalization.

The changing step is characterized in that, for example, the initially preset CIR threshold is changed to a new CIR threshold only when the number of errors in the FEC block exceeds the minimum value (min). The minimum value includes, for example, 0 (zero).

A television according to an embodiment of the present invention includes a tuner that selects a specific channel, determines whether a noise signal received from the specific channel is above a preset channel impulse response (CIR) threshold, and performs FEC. (forward error correction) A controller that changes the initially preset CIR threshold value to a new CIR threshold value based on information about the number of errors in the block, a memory that stores the new CIR threshold value for the specific channel, and When the specific channel is reselected, it is designed to include a demodulator that demodulates the signal received from the specific channel according to the CIR threshold value stored in the memory.

One embodiment of the present invention has the technical effect of providing a process for normally outputting video and audio even in poor signal conditions by adjusting settings to suit the signal of the corresponding channel in an RF (Radio Frequency) signal environment.

Another embodiment of the present invention stores the newly set CIR threshold value of each channel in memory (e.g., non-volatile memory or eMMC (Embedded Multi-Media Controller), etc.), thereby enabling channel switching with just one initial setting. There is a technical effect that improves speed.

The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. will be.

Figure 1 shows a flow chart when a fixed CIR threshold is used in a TV channel tuning process according to the prior art.
Figure 2 shows components inside a TV according to an embodiment of the present invention.
Figure 3 shows components inside a TV and external devices together according to another embodiment of the present invention.
Figure 4 shows a flow chart when a variable CIR threshold is used for each channel in the TV channel tuning process according to an embodiment of the present invention.
Figure 5 illustrates a CIR threshold that varies for each channel, according to an embodiment of the present invention.
Figure 6 is a simplified diagram of the main components of a TV according to an embodiment of the present invention.
And, Figure 7 is a diagram for sequentially explaining the operation of the present invention.

Hereinafter, embodiments disclosed in the present specification will be described in detail with reference to the attached drawings. However, identical or similar components will be assigned the same reference numbers regardless of reference numerals, and duplicate descriptions thereof will be omitted. The suffixes “module” and “part” for components used in the following description are given or used interchangeably only for the ease of preparing the specification, and do not have distinct meanings or roles in themselves. Additionally, in describing the embodiments disclosed in this specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed descriptions will be omitted. In addition, the attached drawings are only for easy understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the attached drawings, and all changes included in the spirit and technical scope of the present invention are not limited. , should be understood to include equivalents or substitutes.

Terms containing ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Figure 1 shows a flow chart when a fixed CIR threshold is used in a TV channel tuning process according to the prior art.

According to the prior art, a TV capable of receiving and processing ATSC 3.0 broadcasting services controls a tuner, etc. to select a random channel (S101).

And at this time, the TV according to the prior art extracts a fixed CIR (Channel Impulse Response) threshold value determined during the product manufacturing process (S102).

Furthermore, the TV according to the prior art is designed to perform a channel estimation/equalization process (S103) and determine the number of errors in the FEC (Forward Error Correction) block (S104).

If the number of errors in the FEC block is 0 or at an insignificant level, the signal received from the channel selected in step S101 is designed to be demodulated and output (S105).

On the other hand, if the number of errors in the FEC block exceeds a certain level, and it is impossible to decode the signal received from the channel selected in step S101, there is a problem that a broken screen is displayed or skipped to the next channel.

One of the main reasons why this problem occurs is because only a fixed CIR threshold is used in step S102. Specific measures to solve this problem will be described in more detail below in Figure 4.

Meanwhile, in this specification, the present invention is mainly explained using, for example, a TV that processes ATSC 3.0 broadcasting services, but those skilled in the art can apply the present invention to any type of multimedia device in which channel tuning is performed.

Figure 2 shows components inside a TV according to an embodiment of the present invention.

The present invention is applicable to various TV products, for example, the European standard DVB (Digital Video Broadcasting) standard or the North American/Korean standard ATSC (Advanced Television Systems Committee) 3.0 standard.

However, in Figure 2, the process in which the TV 100 performs the first service scan operation according to the ATSC 3.0 standard will be described by way of example, but the scope of the present invention should be determined according to the matters stated in the patent claims.

The tuner 110 determines whether a signal exists using a predefined frequency list. When a signal is detected at a given frequency, the baseband processor 120 extracts the L1 signaling of the preamble.

Furthermore, the baseband processor 120 transmits PLP (Physical Layer Pipe) data including link layer signaling and LLS (Low Level Signaling) to the middleware 130, and the middleware 130 receives the PLP data from the PLP data. Link layer signaling and LLS can be extracted.

Meanwhile, the middleware 130 includes a signaling manager 140 and a channel manager 150.

The middleware 130 receives PLP data including link layer signaling and LLS from the baseband processor 120 and then passes the data to an appropriate parser.

For example, the middleware 130 extracts a Link Mapping Table (LMT) from the link layer signaling and passes the LMT to the LMT parser 141. Furthermore, the middleware 130 extracts a Service List Table (SLT) from the LLS and passes the SLT to the SLT parser 142.

The LMT parser 141 parses the LMT and extracts first information (eg, PLPID, session information (IP address and port number), etc.) needed to create a channel map.

The SLT parser 142 parses the SLT and extracts second information (eg, service id, service name, etc.) required to create a channel map.

The extracted first information and second information are stored in the channel map 151.

Figure 3 shows components inside a TV and external devices together according to another embodiment of the present invention. Those skilled in the art may implement the present invention by combining some components with reference to FIGS. 2 and 3. For example, the baseband processor 120 and middleware 130 shown in FIG. 2 may be included in the controller 209 shown in FIG. 3.

Meanwhile, the TV 200 shown in FIG. 3 includes various components, but the scope of rights of the present invention is not limited thereto, and the scope of rights must be confirmed according to the matters stated in the patent claims.

Furthermore, the components inside the TV 200 shown in FIG. 3 may be controlled through the controller 209, and each component may be connected directly or indirectly. That is, although not shown in FIG. 3, all components inside the TV 200 of FIG. 3 are designed to transmit and receive control signals and/or data directly or indirectly.

First, the tuner 201 receives a broadcast signal through an antenna, etc., and the demux or demultiplexer 202 demultiplexes the audio data and video data included in the broadcast signal.

The audio decoder 203 decodes audio data (encoded state) included in the broadcast signal, and the video decoder 204 decodes video data (encoded state) included in the broadcast signal.

The decoded audio data is output through the audio output unit 207. For example, the audio output unit 207 may be a speaker attached to the TV 200 or a speaker separated from the TV 200.

Meanwhile, the decoded video data is directly output through the video output unit 208. Alternatively, the mixer 205 mixes the menu data and video data generated by the OSD generator 206 and then transmits the mixture to the video output unit 208.

The memory 215 stores various control data and commands for controlling the TV 200, and the controller 209 can control all components within the TV by referring to the memory 215.

Furthermore, the TV 200 transmits and receives data through communication with various external devices around it. For example, video/audio data is received from STB 220 via wired interface 212, and these are processed in audio decoder 203 and video decoder 204, respectively. Alternatively, it is possible for the received video/audio data to be output directly through the audio output unit 207 and video output unit 208 without going through the decoders 203 and 204.

Via the wireless communication module 213, various data are transmitted and received with the mobile device 230 (e.g., mobile phone/wearable device, etc.), and the IR infrared signal of the remote control 240 is received through the infrared sensor 214. do. Alternatively, the remote control 240 capable of Bluetooth communication such as BT transmits and receives various data to and from the TV via the wireless communication module 213.

Figure 4 shows a flow chart when a variable CIR threshold is used for each channel in the TV channel tuning process according to an embodiment of the present invention. In particular, when compared to the previously described flow chart of FIG. 1, steps S406, S407, and S408 of FIG. 4 are main features according to an embodiment of the present invention.

First, a multimedia device (eg, TV, etc.) according to an embodiment of the present invention selects a random channel for ATSC 3.0 service (S401).

At this time, the multimedia device according to an embodiment of the present invention extracts the CIR threshold value derived during the product manufacturing process (S402). However, unlike the prior art described above in FIG. 1, a feature of the present invention is that the CIR threshold is set differently for each channel.

Additionally, the multimedia device performs channel estimation and equalization operations on signals received from the corresponding channel (S403). To be more specific, if the noise signal included in the broadcast signal received from the selected channel exceeds the CIR threshold initially set in step S402, a filter for channel equalization (Kang Hak-sang, named EQ filter) (sometimes) is turned on.

On the other hand, if the noise signal included in the broadcast signal received from the selected channel is less than the CIR threshold initially set in step S402, the filter for channel equalization (can also be called an EQ filter) is turned off.

Furthermore, the multimedia device is designed to determine the number of errors in the FEC block included in the broadcast signal (S404).

If the number of errors as a result of the determination (S404) is 0 or corresponds to the minimum value (min.), the multimedia device can demodulate the signal of the corresponding channel and output AV data normally (S405).

On the other hand, if the number of errors as a result of the determination (S404) is 0 or greater than the minimum value (min.), the multimedia device does not immediately demodulate the signal of the corresponding channel, but sets the CIR threshold value initially set in step S402. Change (S406). A more specific embodiment of changing and setting the CIR threshold differently for each channel will be described in more detail with reference to FIG. 5 below.

That is, unlike the prior art, the multimedia device according to an embodiment of the present invention is designed to sequentially change the CIR threshold and search for the optimal CIR threshold without errors in the FEC block.

As a result of testing while changing the CIR threshold value, if a specific CIR threshold value that does not cause an error in the FEC block is derived, the multimedia device according to an embodiment of the present invention completes setting with the specific CIR threshold value (S407 ).

And, the multimedia device is designed to store the set CIR threshold in memory (eg, non-volatile memory or eMMC, etc.) (S408). Therefore, from this point on, the CIR threshold value in step S402 corresponds to the CIR threshold value newly stored in the memory (the value confirmed in step S408 is used).

Therefore, by using the optimal CIR threshold for each channel, there is an advantage of being able to solve all problems such as video/audio disruption and skipping during channel tuning in any signal environment.

Figure 5 illustrates a CIR threshold that varies for each channel, according to an embodiment of the present invention. First, starting from the conclusion according to FIG. 5, the CIR threshold of channel 1 (CH 1) is set to the third threshold (Threshold 3), while the CIR threshold of channel 2 (CH 2) is set to the second threshold. It is set to Threshold 2. Hereinafter, it will be described in more detail with reference to FIG. 5.

For example, let's assume that the CIR threshold can be set from 0 to 10. In addition, let us further assume that the CIR threshold value is determined to be 2 (Threshold 2 shown in FIG. 5) during the production process of the multimedia device (for example, TV, etc.) to which the present invention is applied.

First, let's explain the process of adjusting the CIR threshold for channel 1 (CH 1).

It is assumed that the initial CIR threshold is set to 2 (Threshold 2), and as shown in FIG. 2, the size of the noise signal in channel 1 exceeds Threshold 2. Accordingly, the EQ filter is turned on. However, since there are currently almost no reflected signals through channel 1 and only white noise is being detected, there is a high possibility of malfunction when the EQ filter is turned on (i.e., the number of errors in the FEC block shown in FIG. 4 is 0 or exceeds the minimum value, see step S404, etc.).

Therefore, by changing the CIR threshold to 3 (Threshold 3) in channel 1, the EQ filter is turned off (in this case, because the noise signal of channel 1 becomes smaller than CIR threshold 3). When designed in this way, there is an advantage that the possibility of malfunction is reduced by not recognizing white noise as a noise component.

As described above, assume that the CIR threshold for channel 1 has been changed to 3.

As shown in Figure 5, the size of the noise signal in channel 2 also exceeds Threshold 2. Therefore, the EQ filter is turned off. However, since there are currently a significant number of reflected signals through channel 2 (i.e., the number of errors in the FEC block shown in FIG. 4 exceeds 0 or the minimum value, see step S404, etc.), the EQ filter is used. There is a need to turn it on.

Therefore, in channel 2, by changing the CIR threshold to 2 (Threshold 2), the EQ filter is turned on (in this case, because the noise signal in channel 2 becomes larger than CIR threshold 2). When designed in this way, it becomes possible for the multimedia device according to an embodiment of the present invention to recognize even small noise components due to reflected signals and to normally restore the original signal.

Meanwhile, according to another embodiment of the present invention, when changing the CIR threshold, there is a technical effect of being able to more quickly obtain the optimal CIR threshold by trying from the adjacent threshold. Experimentally, the design takes into account that the difference between the initially set CIR threshold and the optimal CIR threshold for each channel is not large.

Figure 6 is a simplified diagram of the main components of a TV according to an embodiment of the present invention. A person skilled in the art will say that supplementary interpretation of FIG. 6 with reference to the previous drawings also falls within the scope of other rights of the present invention.

The television 600 according to an embodiment of the present invention includes a tuner 601, a controller 602, a memory 603, and a demodulator 604. Of course, the present invention is applicable to, for example, a TV that receives and processes ATSC 3.0 broadcast signals, but is also applicable to other multimedia devices.

The tuner 601 is designed to select a specific channel. Then, a broadcast signal including, for example, audio/video data, etc. is received from the selected specific channel.

The controller 602 determines whether the noise signal received from the specific channel is greater than or equal to an initially preset channel impulse response (CIR) threshold, and provides information about the number of errors in the forward error correction (FEC) block. Based on this, the initially preset CIR threshold is changed to a new CIR threshold. As described above, according to the prior art, there was a problem in that the CIR threshold value determined during the product manufacturing process had to be used continuously without change.

Memory 603 stores the new CIR threshold for the specific channel, and demodulator 604, when the specific channel is reselected, selects the specific channel according to the CIR threshold stored in memory 603. It is designed to demodulate the received signal.

The memory 603 shown in FIG. 6 corresponds to, for example, a non-volatile memory, and maps and stores CIR threshold values that vary for each channel.

The controller 602 turns on a filter for channel equalization when the noise signal included in the broadcast signal exceeds the CIR threshold. On the other hand, when the noise signal is less than the CIR threshold, the filter for channel equalization is turned off.

Furthermore, the controller 602 is designed to change the initially preset CIR threshold to a new CIR threshold only when the number of errors in the FEC block exceeds the minimum value (min). The minimum value includes, for example, 0 (zero). In other words, the design takes into account that if the number of errors in the FEC block is less than the minimum value (min), there is no need to adjust the CIR threshold.

And, Figure 7 is a diagram for sequentially explaining the operation of the present invention. Those skilled in the art will recognize that supplementary interpretation of FIG. 6 with reference to previous drawings (in particular, FIG. 4, etc.) also falls within the scope of other rights of the present invention.

The multimedia device according to an embodiment of the present invention selects a specific channel (eg, channel number 2 (Ch. 2)) at a first time. Here, the first time may mean, for example, the time when the multimedia device performs the first automatic channel scan, as shown in (a) of FIG. 7.

Next, the multimedia device determines whether the noise signal received from a specific channel (eg, channel 2) is greater than or equal to an initially preset channel impulse response (CIR) threshold.

Furthermore, the multimedia device is designed to change the initially preset CIR threshold to a new CIR threshold based on information about the number of errors in the forward error correction (FEC) block. Accordingly, the multimedia device stores the new CIR threshold for the specific channel in memory.

Finally, when the specific channel is reselected at a second time (for example, the user selects channel number 2 using the TV's remote control), the multimedia device according to an embodiment of the present invention stores the CIR in the memory. The signal received from the specific channel is demodulated according to the threshold.

Meanwhile, according to one embodiment of the present invention, it is also possible to continuously use the CIR threshold for all channels during a channel scan operation. This is because there is no need to change the CIR threshold determined for each channel again after channel scanning.

However, in the ATSC 3.0 broadcasting environment, there are cases where the TV receives IP data through Wi-Fi, etc., so the signal environment may vary significantly each time the channel is changed (even for the same channel). Therefore, in consideration of the characteristics of the ATSC 3.0 broadcasting environment, changing the CIR threshold in real time whenever a channel change command is received also falls within the scope of other rights of the present invention.

In other words, the multimedia device according to an embodiment of the present invention can be implemented only with the tuner, memory, and controller described above.

The tuner selects the first channel, and the controller uses the CIR threshold stored in the memory according to the signal status received from the first channel.

On the other hand, when a second channel different from the first channel is selected by the tuner, the controller is designed to use a CIR threshold value different from the CIR threshold value stored in the memory, depending on the signal state received from the second channel. . While the prior art uses the CIR threshold determined at the time of manufacturing a multimedia device, for example, a TV, without any correction, an embodiment of the present invention changes the CIR threshold in real time according to the signal status for each channel. There is a clear technical difference in that.

The above-described present invention can be implemented as computer-readable code on a program-recorded medium. Computer-readable media includes all types of recording devices that store data that can be read by a computer system. Examples of computer-readable media include HDD (Hard Disk Drive), SSD (Solid State Disk), SDD (Silicon Disk Drive), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. This also includes those implemented in the form of carrier waves (e.g., transmission via the Internet). Additionally, the computer may include a control unit. Accordingly, the above detailed description should not be construed as restrictive in all respects and should be considered illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

600: Television
601: Tuner
602: Controller
603: memory
604: demodulator

Claims (12)

In a method of controlling a multimedia device,
selecting a specific channel at a first time;
determining whether a noise signal received from the specific channel is greater than or equal to an initially preset channel impulse response (CIR) threshold;
changing the initially preset CIR threshold to a new CIR threshold based on information about the number of errors in a forward error correction (FEC) block;
storing a new CIR threshold for the specific channel in memory; and
When the specific channel is reselected at a second time, demodulating the signal received from the specific channel according to the CIR threshold value stored in the memory.
A control method for a multimedia device comprising: According to paragraph 1,
The memory is,
A control method for a multimedia device, characterized in that CIR threshold values are mapped and stored for each channel. According to paragraph 1,
The above judgment step is,
If the noise signal exceeds the CIR threshold, turning on a filter for channel equalization; and
If the noise signal is less than the CIR threshold, turning off the filter for channel equalization.
A method of controlling a multimedia device further comprising: According to paragraph 1,
The above changing steps are:
A method of controlling a multimedia device, characterized in that the initially preset CIR threshold is changed to a new CIR threshold only when the number of errors in the FEC block exceeds the minimum value (min). According to paragraph 4,
A method of controlling a multimedia device, wherein the minimum value includes 0 (zero). In television,
tuner to select specific channels;
Determine whether the noise signal received from the specific channel is above an initially preset CIR (channel impulse response) threshold,
a controller that changes the initially preset CIR threshold to a new CIR threshold based on information about the number of errors in a forward error correction (FEC) block;
a memory storing a new CIR threshold for the specific channel; and
When the specific channel is reselected, a demodulator that demodulates the signal received from the specific channel according to the CIR threshold stored in the memory.
A television comprising: According to clause 6,
The memory corresponds to non-volatile memory,
A television characterized by mapping and storing CIR threshold values for each channel. According to clause 6,
The controller is,
If the noise signal exceeds the CIR threshold, turn on a filter for channel equalization, and
A television, characterized in that when the noise signal is less than the CIR threshold, the filter for channel equalization is turned off. According to clause 6,
The controller is,
A television, characterized in that the initially preset CIR threshold value is changed to a new CIR threshold value only when the number of errors in the FEC block exceeds the minimum value (min). According to clause 9,
A television, characterized in that the minimum value includes 0 (zero). In a method of controlling a multimedia device,
selecting a first channel;
maintaining a CIR threshold stored in a memory according to a signal state received from the first channel;
selecting a second channel different from the first channel; and
Using a CIR threshold value different from the CIR threshold value stored in the memory according to the signal state received from the second channel.
A control method for a multimedia device comprising: In multimedia devices,
a tuner for selecting a first channel; and
A controller that uses a CIR threshold stored in memory according to the signal state received from the first channel.
Including,
The controller is,
When a second channel different from the first channel is selected,
A multimedia device characterized in that, depending on the signal state received from the second channel, a CIR threshold value different from the CIR threshold value stored in the memory is used.