KR101561537B1 - Method and Apparatus for Providing Emergency Alert Message on Active Standby Mode - Google Patents

Abstract

The present invention relates to a standby mode operation management method capable of operating in a stand-by mode for power saving in a broadcast receiving apparatus, and capable of processing a disaster broadcast alarm message and outputting disaster broadcast contents in an active standby mode. The standby mode management method of a broadcast receiving apparatus of the present invention includes generating a emergency alert descriptor (emergency_alert_descriptor) capable of receiving a broadcast receiving apparatus in an active standby mode and transmitting the emergency alert descriptor to a broadcast receiving apparatus, The device is switched from the active standby mode to the on mode so that the emergency alert message processing and emergency alert broadcast contents are output.

Description

[0001] The present invention relates to a method and an apparatus for providing a disaster alarm message in an active standby mode,

The present invention relates to a standby mode operation management method capable of operating in a standby mode for power saving in a broadcast receiving apparatus, and capable of processing a disaster alarm message and outputting contents of a disaster broadcast in an active standby mode.

The set-top box receives broadcasting signals through terrestrial, satellite, cable and internet, separates them into AV contents, and outputs them to a display device. The set-top box has a normal mode in which all operations are performed, a standby mode in which only some functions are performed, and an off mode in which all operations can not be performed because the power is off. The power consumption decreases in the order of the normal mode, the standby mode and the off mode. When the set-top box is in the normal mode, the power consumption increases. When the set-top box is in the off mode, the boot time becomes long and it is inconvenient to use.

The set-top box consumes only 70 to 80% of the power consumption of the normal mode in the standby mode, but consumes power in both the normal mode and the standby mode. In addition, the world has shown a tendency to tighten power consumption regulations under the transnational banner of energy conservation and environmental protection. Accordingly, each country is required to develop a technology capable of preventing power waste by imposing a standby mode of the set-top box.

In order to solve the above problems, a technique has been developed in which the set-top box performs its function in the standby mode to reduce power consumption. A broadcast receiving apparatus standby mode management method using external signaling according to Korean Patent Application Publication No. KR 2012-0116727A is a method of managing standby mode by exchanging advance information with a broadcasting company and recognizing the reception time of management information such as broadcasting information update in advance and then switching to a passive standby mode , And automatically returns from the passive standby mode to the active standby mode at the management information reception time to receive the management information. The present patent determines whether it is a normal mode, an active standby mode, or a passive standby mode, and determines whether it is a background function, that is, the management information reception time (S180) I am suggesting.

Meanwhile, in a cable broadcasting system and a terrestrial broadcasting system, an emergency alert message (Emergency Alert Message: EAM) is transmitted to notify an emergency when a natural disaster such as an earthquake or a flood, or an emergency such as terrorism or arson occurs. The broadcast receiver must receive and process the emergency alert message to change the emergency alert channel to an emergency alert channel and / or output content related to a disaster broadcast in the form of text or voice. That is, in order to process the emergency alert message and output the contents of the broadcast, the broadcast receiver must switch from the standby mode to the on mode.

However, Korean Patent Publication No. KR 2012-0116727A has a problem that the function of the A / V decoder and the output unit is not performed in the active standby mode, but the emergency alarm message can not be coped even in the active standby mode.

It is an object of the present invention to provide a set-top box and a method for processing an emergency warning message even in an active standby mode.

Another object of the present invention is to provide external signaling for on-mode switching for processing an emergency alert message in active standby mode.

According to an aspect of the present invention, there is provided a method of generating an emergency alert descriptor (emergency_alert_descriptor) capable of receiving a broadcast receiving apparatus in an active standby mode; And transmitting the descriptor generated in the generating step to the broadcast receiving apparatus.

Preferably, the descriptor indicates that current disaster-related information is transmitted from a head end of a broadcasting company.

Preferably, the descriptor controls the broadcast receiving apparatus to return from the active standby mode to the on-mode upon reception.

Preferably, the descriptor is included in an NIT (Network Information Table) of a broadcast data service standard.

In another aspect of the present invention, there is provided a method for detecting a disaster alert descriptor, the method comprising: checking whether a disaster alert descriptor exists among stream signals received in an active standby mode; Returning the power state of the receiver to the on mode when the disaster alert descriptor is received as a result of the check; And receiving and processing a disaster alarm message after returning to the normal mode.

Preferably, the descriptor indicates that current disaster-related information is transmitted from a head end of a broadcasting company.

Preferably, the descriptor is included in an NIT (Network Information Table) of a broadcast data service standard.

According to another aspect of the present invention, there is provided a tuner for tuning a broadcast signal; A demodulator for demodulating a broadcast signal selected through the tuner; And a processor for converting the broadcast receiving apparatus into an on mode when receiving a disaster alert descriptor among the stream signals received in the active standby mode, and receiving and processing the disaster alert message.

In the present invention, when a broadcast receiver has an emergency alert message in an active standby mode, the broadcast receiver switches to an on mode and provides urgent broadcasting to a user.

The present invention enables a broadcast receiver to cope with a disaster alarm message while effectively managing the operation of the standby mode.

1 is a flowchart showing a conventional method of switching a set-top box mode.
2 is a diagram illustrating a broadcast service system to which the present invention is applicable.
3 is a block diagram of the set-top box shown in FIG.
Figure 4 is a diagram listing external signaling descriptors.
5 is a diagram showing a structure of a power management descriptor (power_management_descriptor).
6 is a diagram showing a description of information stored in a terminal power mode (terminal_power_mode).
FIG. 7 is a diagram illustrating information included in the service mode (service_mode). FIG.
8 is a diagram showing a structure of a firmware update descriptor (fw_update_descriptor).
9 is a diagram showing a structure of an EIT update descriptor (EIT_update_descriptor).
10 is a diagram showing a description of information included in the EIT type (EIT_type).
11 is a diagram showing a structure of a terminal management descriptor (terminal_management_descriptor).
12 is a diagram showing a structure of a emergency alert descriptor (emergency_alert_descriptor).
FIG. 13 is a diagram illustrating switching between an active standby mode and a passive standby mode according to the present invention's external signaling and an internal timer, and switching to an on mode in an active standby mode by external signaling.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. In order to facilitate a thorough understanding of the present invention, the same reference numerals are used for the same means regardless of the number of the drawings.

2 is a diagram illustrating a broadcast service system to which the present invention is applicable. The broadcasting system to which the present invention is applicable includes a broadcasting company head-end 10, a set-top box 100, a TV 200, and a remote controller 300.

2, the set-top box 100 decodes a broadcast signal received from the broadcasting company head end 10 through the Internet, a cable, a satellite, etc. to restore a video signal and a voice signal, ).

The TV 200 is a type of AV output device that outputs a video signal and a voice signal provided from the set top box 100 through a display and a speaker. Although the TV has been described as an example in the embodiment of the present invention, the present invention can be applied to any AV output device capable of outputting images such as a monitor.

The remote controller 300 is a user input device for receiving a command of a user and delivering it to the corresponding device. The remote controller 300 is used not only for the set-top box 100 but also for inputting a user command for the TV 200. [

3 is a block diagram showing the set-top box shown in Fig. 2 as a reference numeral "100 ". The set-top box 100 is a type of broadcast receiving apparatus and can provide a real-time broadcasting service and a content providing service.

3, the set-top box 100 includes a tuner 110, a demodulator 115, a memory 120, a processor 130, an RTC 135, a front panel 140, An Ethernet interface 150, an IR receiving unit 155, a USB interface 160, a power supply unit 170, and a power control unit 175.

The tuner 110 selects a broadcast signal of a broadcast channel selected by a user from among broadcast signals received from a terrestrial antenna, a cable, a satellite antenna, the Internet, etc., and the demodulator 115 demodulates the broadcast signal selected by the tuner 110 Demodulate.

The processor 130 demultiplexes the demodulated broadcast signal into a video signal, an audio signal, and a SI (Service Information) signal in the demodulator 115. In addition, the processor 130 performs video decoding and signal processing on the video signal, and performs audio decoding and signal processing on the audio signal.

In addition, the processor 130 controls the overall operation of the set-top box 100. In particular, the processor 130 controls switching of the operation mode of the set-top box 100, which will be described later in detail.

The memory 120 provides storage space required for decoding and signal processing by the processor 130. The RTC (Real Time Clock) 135 functions as a timer.

The front panel 140 is a panel provided on the front of the set-top box 100 and includes a display for displaying the current time and an operation state of the set-top box 100, and buttons for directly inputting a user command.

In addition, the front panel 140 is provided with an IR receiving unit 155 and a USB interface 160, which will be described later.

The AV output unit 145 transfers the audio signal decoded and signal-processed by the processor 130 and the video signal to the connected TV. The AV output method by the AV output unit 145 may be Composite, Component, HDMI, DVI, or the like.

The Ethernet interface 150 provides a network interface for accessing an external network.

The IR receiving unit 155 receives the user command inputted through the remote controller and transmits the user command to the processor 130. The USB interface 160 is connected to be able to communicate with an external device according to the USB standard.

The power supply unit 170 applies power to the blocks 110, 115, 120, 130, 135, 140, 145, 150, 155 and 160 provided in the set top box 100.

The power supply control unit 175 controls the power supply operation of the power supply unit 170 according to the operation mode of the set top box 100 determined by the processor 130. The power supply operation control is performed by a method of limiting the blocks to which the power supply is applied by the power supply controller 170.

The operation mode of the set-top box will be described below. The set-top box 100 has four operation modes for reducing power consumption: a normal mode, an active standby mode, a passive standby mode, and an off mode.

Prior to examining the operation mode of the set top box 100, functions performed according to the respective operation modes are different. First, the functions are defined and the operation modes are examined.

The functions of the set-top box 100 include a main function and a background function. The main function is a function for a user and includes broadcasting, VOD, recording, user application execution, and user application downloading. The background function is a function for the set-top box 100 and includes software update, EIT (Event Information Table) update, set-top box management, and the like.

The active mode is a state in which power is supplied to the set-top box 100 and normal service can be performed to perform both the main function and the background function. In the on mode, when the user turns off the power switch, the set-top box 100 switches to the off mode, and when the user inputs the OFF button, the set-top box 100 switches to the active standby mode to be described later.

In the active standby mode, power is supplied to the set-top box 100, the main function can not be performed, and only the background function can be performed. The APD (Auto Power Down) And can be switched to another mode by remote control or internal / external signaling. In the active standby mode, the switchover to the passive standby mode is performed by the APD policy or the timeout technique.

The passive standby mode is a mode in which power is supplied to the set-top box 100 and both the main function and the background function can not be performed, and the mode can be switched to another mode through a remote control input or internal signaling State. The set-top box 100 can only perform a function of displaying the current time and the operation state through the front panel and detecting whether a user command is input.

The off mode is a mode in which the set-top box 100 is not supplied with power and can not perform any function. That is, neither the display function nor the detection function performed in the passive standby mode is performed at all.

Next, the specification of the external signaling provided by the head end 10 of the broadcaster will be described in detail. In the following, the data service standard of the digital cable broadcasting is an extension standard of the digital cable broadcasting data broadcasting provisional standard, the digital satellite broadcasting and the IPTV data service standard is the extension standard of the DVB-SI standard specification, It should be noted that the technical idea of the invention may be applied to other standard specifications other than the standard specification.

(1) External signaling descriptor for set-top box standby mode

FIG. 4 shows external signaling descriptors for setting the mode switching condition between the active standby mode and the passive standby mode and the on mode switching in the active standby mode. These descriptors are generated by the head-end 10 of the broadcaster and transmitted to the set-top box 100.

As shown in Figure 4, in the external signaling descriptors,

1) a power management descriptor,

2) a firmware update descriptor (fw_update_descriptor),

3) EIT update descriptor (EIT_update_descriptor),

4) Terminal management descriptor (terminal_management_descriptor)

5) Disaster alert descriptor (emergency_alert_descriptor)

Is included.

Also, as shown in FIG. 4, tags and storage positions for external signaling descriptors can be confirmed.

Hereinafter, each of the external signaling descriptors will be described in detail one by one.

(1-1) Power Management Descriptor (power_management_descriptor)

FIG. 5 shows a structure of a power management descriptor (power_management_descriptor). The power management descriptor (power_management_descriptor) is a descriptor containing information to be referred to when the set-top box 100 operates in the standby mode, and represents a power management mode supported by the broadcast transmission / reception terminal and an external signaling list supported by the corresponding broadcasting company .

Specifically, as shown in FIG. 5, information on a descriptor tag (descriptor_tag), a descriptor length (descriptor_length), a terminal power management mode (terminal_power_mode) and a service mode (service_mode) is stored in the power management descriptor (power_management_descriptor) have.

The descriptor tag (descriptor_tag) is a tag for identifying the power management descriptor (power_management_descriptor), and it can be seen that it is '0x80' with reference to FIG.

The descriptor length (descriptor_length) is information on the length of the power management descriptor (power_management_descriptor).

In the terminal power mode (terminal_power_mode), information about a standby mode to be supported by the set top box 100 is stored. Specifically, '0', '1' or '2' is recorded in the terminal power mode (terminal_power_mode) as shown in FIG. 6,

1) '0' indicates that the set-top box 100 should always be in the on-mode (that is, when the set-top box 100 does not need to support the standby mode)

2) '1' indicates that when the set-top box 100 is to be in the standby mode and supports the manual-standby mode,

3) '2' indicates that the set-top box 100 should support the active-standby mode in addition to the passive-standby mode in the standby mode.

The service mode (service_mode) contains information about a list for guiding external signaling descriptors provided by the headend 10 of the broadcaster. In other words, the information included in the service mode (service_mode) may be information on the background-functions that the set-top box 100 can perform in the active-standby mode and on-mode switching for receiving disaster broadcasting information.

The information stored in the service mode (service_mode) is as shown in FIG. In the service mode, 'F' is a firmware update descriptor (fw_update_descriptor), E is an EIT update descriptor (EIT_update_descriptor), M is a terminal management descriptor (terminal_management_descriptor), and D is an external emergency signaling descriptor (emergency_alert_descriptor) .

(1-2) Firmware update descriptor (fw_update_descriptor)

FIG. 8 shows the structure of the firmware update descriptor (fw_update_descriptor). The firmware update descriptor (fw_update_descriptor) is a descriptor containing related information about firmware update to be performed in the active standby mode by the set top box 100.

Specifically, the firmware update descriptor fw_update_descriptor includes information on a descriptor tag (descriptor_tag), a descriptor length (descriptor_length), a start time (start_time), and a duration as shown in FIG.

The descriptor tag (descriptor_tag) is a tag for identifying the firmware update descriptor (fw_update_descriptor), and it can be seen that it is '0x81' with reference to FIG.

The descriptor length (descriptor_length) is information on the length of the firmware update descriptor (fw_update_descriptor).

The start time (start_time) stores information on the firmware update start time of the set-top box 100, that is, the time when the head-end 10 of the broadcaster starts to provide the updated firmware to the set-top box 100 . The format of the start time (start_time) uses a combination of UTC (Universal Time, CO-ordinated) and MJD (Modified Julian Date).

The valid duration includes information on the firmware update valid period of the set-top box 100, that is, the period during which the head-end 10 of the broadcaster provides the updated firmware to the set-top box 100. The duration can be expressed as a code listing hours, minutes, and seconds (for example, 01:45:30 to 0x014530).

(1-3) EIT update descriptor (EIT_update_descriptor)

FIG. 9 shows a structure of an EIT update descriptor (EIT_update_descriptor). The EIT update descriptor (EIT_update_descriptor) is a descriptor in which related information about the EIT update to be performed by the set top box 100 in the active-standby mode is stored.

15, the EIT update descriptor EIT_update_descriptor includes a descriptor tag descriptor_length, an EIT type EIT_type, a previous descriptor number last_descriptor_number, a start_time, Information on the duration is included.

The descriptor tag (descriptor_tag) is a tag for identifying the EIT update descriptor (EIT_update_descriptor), which is '0x82' referring to FIG.

The descriptor length (descriptor_length) is information on the length of the EIT update descriptor (EIT_update_descriptor).

The EIT type (EIT_type) contains information about the type of EIT to be transmitted. Specifically, as shown in FIG. 10, 1) EIT type (EIT_type) includes '1' in the case where EIT is EIT p / f type and 2) EIT type In this case, the EIT is the EIT sch type.

In the previous descriptor number (last_descriptor_number), information on the version of the last transmitted EIT is recorded.

In the start time (start_time), information on the EIT update start time of the set top box 100, that is, the time when the head end 10 of the broadcasting company starts providing the updated EIT to the set top box 100 is recorded . The format of the start time (start_time) uses a combination of UTC (Universal Time, CO-ordinated) and MJD (Modified Julian Date).

The valid duration includes information about the EIT update valid period of the set top box 100, that is, the period during which the head end 10 of the broadcasting company provides the updated EIT to the set top box 100. The duration can be expressed as a code listing hours, minutes, and seconds (for example, 01:45:30 to 0x014530).

(1-4) Terminal management descriptor (terminal_management_descriptor)

FIG. 11 shows a structure of a terminal management descriptor (terminal_management_descriptor). The terminal management descriptor (terminal_management_descriptor) is a descriptor containing related information for management of the set top box 100 to be performed by the set top box 100 in the active-standby mode.

Specifically, a terminal descriptor_tag, a descriptor_length, a subscriber_id, and individual data (private_data_byte) are stored in the terminal management descriptor (terminal_management_descriptor) as shown in FIG.

The descriptor tag (descriptor_tag) is a tag for identifying the terminal management descriptor (terminal_management_descriptor), and it can be seen that it is '0x84' with reference to FIG.

The descriptor length (descriptor_length) is information on the length of the terminal management descriptor (terminal_management_descriptor).

The subscriber_id is a subscriber terminal identification ID.

The individual data (private_data_byte) is information necessary for managing the set-top box 100, and the specific contents are defined by the broadcasting company.

(1-5) Disaster alert descriptor (emergency_alert_descriptor)

FIG. 12 shows the structure of the emergency_alert_descriptor. The emergency alert descriptor (emergency_alert_descriptor) is a descriptor for signaling for the on-mode switching for the set-top box 100 to receive disaster broadcast information. Indicating that the current disaster-related information is transmitted from the head end of the broadcasting company, the broadcasting receiving apparatus returns from the active standby mode to the receiving-on mode, receives the disaster related message, and outputs the content of the broadcast The purpose.

Specifically, a descriptor tag (descriptor_tag) and a descriptor length (descriptor_length) are recorded in the emergency alert descriptor (emergency_alert_descriptor) as shown in FIG.

The descriptor tag (descriptor_tag) is a tag for identifying the emergency alert descriptor (emergency_alert_descriptor). Referring to FIG. 4, the tag is '0x85'.

The descriptor length (descriptor_length) is information on the length of the emergency alert descriptor (emergency_alert_descriptor).

In the set-top box mode switching, mode switching between the active standby mode and the passive standby mode according to the external signaling of the head-end 10 of the broadcasting company providing the broadcasting and contents and the internal timer, Mode, which will be described below in detail with reference to FIG.

FIG. 13 is a flowchart provided in a description of a method for switching a set-top box mode according to another embodiment of the present invention.

As shown in FIG. 13, when the set-top box 100 is operated in the ON mode (S410), when the OFF button of the panel of the remote controller or the set-top box is inputted by the user (S420-Y) The operation mode of the set top box 100 is switched from the on mode to the active standby mode (S430).

The set-top box 100, which has been switched to the active standby mode in step S430, can not perform the main function and can perform only the background function.

The background function has been described above to include set-top box S / W update, EIT update, and set-top box management. The head-end 10 of the broadcaster has external set- Update time, EIT update time, and set-top box management time.

Accordingly, when the set-top box 100 is switched to the active-standby mode, the processor 130 executes the APD (Auto Power Down) daemon to refer to the external signaling received from the head-end 10 of the broadcaster, And determines the function execution time.

On the other hand, when receiving the emergency alert descriptor in the active standby mode (S440-Y), the processor 130 changes the operation mode of the set-top box 100 to the on mode (S310) Not only receives the emergency broadcast related message, but also receives and decodes at least one of audio data, video data, and character data related to the change to the emergency alert channel and / or the emergency alert broadcast, . On the other hand, if the emergency alert descriptor is not received in the active standby mode, it is determined whether there is an ON button input by the user (S450).

If the user ON button is input during the active standby mode (S450-Y), the processor 130 changes the operation mode of the set-top box 100 to the ON mode (S410). If the user ON button is not input in the active-standby mode (S440-N), the processor 130 determines whether the background-function is being performed in the set-top box 100 (S460).

If it is determined in step S460 that the background-function is being performed (S460-Y), the processor 130 maintains the operation mode of the set-top box 100 in the active-standby mode (S430).

If it is determined in step S460 that the background function is not being performed (S460-N), the processor 130 switches the operation mode of the set-top box 100 to the passive standby mode (S470).

When the set top box 100 is switched to the passive standby mode, the processor 130 operates a timer for transitioning from the passive standby mode to the active standby mode to perform the next background function.

The set-top box 100 switched to the passive-standby mode by step S470 can not perform the main function as well as the background function.

Meanwhile, when the ON button of the user is input in the passive-standby mode (S480-Y), the processor 130 changes the operation mode of the set-top box 100 to the ON mode (S410).

If the ON button of the user is not input in the passive-standby mode (S480-N), the processor 130 determines whether the background-function execution time has arrived by using the timer (S490).

If it is determined in S490 that the background-function execution time has arrived (S490-Y), the processor 130 switches the operation mode of the set-top box 100 to the active-standby mode (S430).

If it is determined in step S490 that the background-function execution time has not arrived (S490-N), the processor 130 maintains the operation mode of the set-top box 100 in the passive-standby mode (S470).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the present invention can be changed.

10: Broadcaster headend 100: Set-top box
110: Tuner 115: Demodulator
120: memory 130: processor
135: RTC 140: Front panel
145: A / V output unit 150: Ethernet interface
155: IR receiver 160: USB interface
170: Power supply unit 175: Power supply control unit
200: TV 300: Remote control

Claims (8)

Generating a emergency alert descriptor (emergency_alert_descriptor) capable of receiving the broadcast receiving apparatus in the active standby mode;
And transmitting the descriptor generated in the generating step to the broadcast receiving apparatus,
The above-
The broadcast receiving apparatus returns from the active standby mode to the on-mode when receiving the disaster-related information, receives the disaster-related message, and outputs the contents of the disaster broadcast ,
The descriptor is included in an NIT (Network Information Table) of the broadcast data service standard,
The broadcast receiving apparatus includes:
When the background function execution time arrives in the passive standby mode, the active mode is switched to the active standby mode to confirm whether the descriptor has been received
Wherein the standby mode management method comprises:
delete delete delete Checking whether a disaster warning descriptor among the stream signals received in the active standby mode exists;
Returning the power state of the receiver to the on mode when the disaster alert descriptor is received as a result of the check;
Receiving and processing the emergency broadcast alarm message after returning to the normal mode
Lt; / RTI >
The above-
Related information is transmitted from the head end of the broadcasting company, the receiver returns from the active standby mode to the on-mode upon receipt, receives the disaster related message, and outputs the content of the disaster broadcast,
The descriptor is included in an NIT (Network Information Table) of the broadcast data service standard,
And if the background function execution time arrives in the passive standby mode, switching the operation mode to the active standby mode to confirm whether the descriptor has been received
Wherein the broadcast receiving apparatus comprises:
delete delete A tuner for tuning a broadcast signal;
A demodulator for demodulating a broadcast signal selected through the tuner;
And a processor for receiving a disaster alarm message from a stream signal received in an active standby mode and switching the broadcast receiver apparatus to an on mode to receive and process a disaster broadcast alarm message,
The above-
The broadcast receiving apparatus returns from the active standby mode to the on-mode when receiving the disaster-related information, receives the disaster-related message, and outputs the contents of the disaster broadcast ,
The descriptor is included in an NIT (Network Information Table) of the broadcast data service standard,
The processor comprising:
When the background function execution time arrives in the passive standby mode, the active mode is switched to the active standby mode to confirm whether the descriptor has been received
And the broadcast receiving apparatus.

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