Satellite broadcasting receiver and method for controlling said satellite broadcasting receiver

Abstract

The present invention relates to a satellite broadcasting receiver and comprises: an interface unit that receives a satellite broadcast signal corresponding to a selected channel and transmits, to a switch, a command signal including channel selection information for channel selection; a tuning unit that demodulates and decodes the received satellite broadcast signal, and detects whether or not a preset bit string is included in decoded data; and a control unit that, when transmission of command signals respectively corresponding to a plurality of channels is requested, transmits each command signal to the switch in a preset order according to a set delay time, determines whether or not it is possible to fix a channel, from a satellite broadcast signal received whenever a command signal is transmitted, and changes the delay time according to whether or not it is possible to fix the channel.

Description

Satellite broadcasting receiver and method for controlling the satellite broadcasting receiver

[0001] The present invention relates to a receiving device for receiving satellite broadcasting signals and a control method for the receiving device.

[0002] Typically, satellite broadcasting refers to a broadcasting method in which broadcast signals emitted from terrestrial broadcasting stations are relayed to the ground by a broadcasting satellite located in a geostationary orbit approximately 35,000 to 36,000 km above the ground, and then radiated to the ground, where each home equipped with a receiver that receives the satellite broadcast signal receives it and plays the broadcast content. This type of satellite broadcasting has the advantage of rarely generating areas with poor reception within the satellite broadcast signal's transmission range, and can play broadcast content with clear picture quality and excellent sound.

[0003] In addition, as digital TV broadcasting becomes more widespread and digital broadcasting content is provided accordingly, satellite broadcasting with the aforementioned advantages is also becoming more popular, and satellite broadcasting receivers equipped with various additional functions such as VOD (Video On Demand) function and home network host function are appearing in addition to simply receiving and decoding digital broadcasting data.

[0004] As satellite broadcasting became more popular and the number of users increased, a method emerged in which multiple receivers control a single satellite antenna via a switch to receive satellite broadcast signals. In addition, in order for multiple receivers to receive satellite broadcast signals using a single satellite antenna, an international standard called DiSEqC (Digital Satellite Equipment Control, hereinafter referred to as DiSEqC) emerged to specify the positioning of the satellite antenna to adjust the elevation and azimuth angles, and the switch control method for the positioning. Accordingly, current satellite broadcast receivers are typically designed to receive satellite broadcast signals by controlling the satellite antenna via a switch in accordance with the DiSEqC standard. In this case, the satellite broadcast receiver transmits a command signal in accordance with the DiSEqC standard to the switch, and the switch adjusts the elevation and azimuth angles of the satellite antenna in accordance with the received command signal.

[0005] The command signal according to the above-mentioned DiJECT standard can be transmitted from the satellite broadcast receiver to the switch to select the TP (Transponder) of the selected channel whenever a channel change is selected in the satellite broadcast receiver. Then, the switch parses and processes the received command signal whenever it receives the command signal, and accordingly, time is required for processing the command signal. In addition, when a satellite broadcast receiver is connected to the switch, the satellite broadcast receiver continuously transmits an analog signal (hereinafter, a tone burst signal) of a certain frequency (e.g., 22 kHz) to the switch, and when the command signal is transmitted to the switch, a pause time is required to distinguish between the tone burst signal and the command signal. Accordingly, even when multiple command signals are transmitted to the receiver continuously as channels are continuously switched in the satellite broadcast receiver (e.g., when the auto tuning function is performed), the satellite broadcast receiver transmits the command signals with a certain delay time (command interval delay) between the command signals or between the tone burst signal and the command signal.

[0006] However, the command signal processing time of the switch may vary depending on the performance of the switch, for example, the performance of the switch's microcomputer (MICOM). However, since the satellite broadcast receiver does not know the exact performance of the switch, the delay time is set to a sufficiently long time to ensure sufficient processing of the command signal even when connected to a switch with poor performance.

[0007] However, as the delay time provided between command signals increases, the time required for channel switching may also increase. Furthermore, if the switch's performance is sufficient, the sufficiently long delay time may act as unnecessary delay time required for channel switching, which may accumulate when multiple command signals are transmitted sequentially, as in the auto-tuning process. Furthermore, this unnecessary delay time may lead to misdiagnosis of a malfunction in the satellite broadcast signal receiver or user complaints.

[0008] The present invention aims to solve the above-mentioned problems and other problems, and provides a satellite broadcasting receiver having a faster channel switching time and a method for controlling the satellite broadcasting receiver.

[0009] In addition, the present invention aims to provide a satellite broadcasting receiver having a command interval delay optimized according to the performance of a switch, and a method for controlling the satellite broadcasting receiver.

[0010] In order to achieve the above or other objects, according to one aspect of the present invention, a satellite broadcasting receiver according to an embodiment of the present invention is characterized by including an interface unit that receives a satellite broadcasting signal corresponding to a channel selected from a switch that selects a satellite broadcasting signal received by a satellite antenna, and transmits a command signal including channel selection information for channel selection to the switch, a tuning unit that demodulates and decodes the satellite broadcasting signal received from the switch and detects whether the decoded data includes a preset bit string, and a control unit that, when transmission of command signals respectively corresponding to a plurality of channels is requested in accordance with a user request or the performance of a preset function, transmits each command signal to the switch in a preset order according to a preset delay time, and controls the tuning unit to demodulate and decode the satellite broadcasting signal received from the switch based on the frequency of the channel corresponding to the transmitted command signal each time a command signal is transmitted, and determines whether fixation of a channel corresponding to the transmitted command signal is possible based on whether the decoded data includes a preset bit string, and changes the delay time depending on whether channel fixation is possible.

[0011] In one embodiment, the control unit is characterized in that, when determining whether channel fixation is possible for a channel selected according to the preset order and, if channel fixation is not possible, increases the delay time by a preset time, and when the increased delay time elapses, transmits a command signal corresponding to the selected channel to the switch again to determine whether the channel is fixed.

[0012] In one embodiment, the tuning unit is characterized by including an oscillation unit that oscillates a local signal having a local frequency corresponding to a frequency of a channel selected according to the preset order, a demodulation unit that demodulates a satellite broadcasting signal whose frequency band is changed according to a satellite broadcasting signal mixed with the local signal, a decoding unit that decodes the demodulated satellite broadcasting signal according to a decoding method corresponding to a preset encoding method, and a channel tuning detection unit that detects the preset bit string from a data stream of the decoded satellite broadcasting signal.

[0013] In one embodiment, the control unit mixes the local signal with a satellite broadcast signal received from the switch to convert the received satellite broadcast signal into a signal having a preset frequency band, and when the selected channel is changed to another channel, controls the oscillation unit to oscillate a local signal having a local frequency corresponding to the frequency of the changed other channel, and mixes the local signal having a local frequency corresponding to the frequency of the other channel with the satellite broadcast signal received from the switch.

[0014] In one embodiment, the control unit corrects an error that may occur in the demodulation process according to at least one of preset error correction methods when demodulation of the satellite broadcast signal is completed, and the preset error correction methods include FEC (Forward Error Correction).

[0015] In one embodiment, when transmission of command signals corresponding to a plurality of channels is requested according to the user request or the performance of a preset function, the control unit determines whether a channel is fixed according to the transmitted command signal by setting a preset minimum delay time, and increases the delay time in stages from the minimum delay time according to the result of the determination of whether the channel is fixed.

[0016] In one embodiment, the minimum delay time is characterized by being a time equal to or greater than the command interval delay time specified in the DiSEqC (Digital Satellite Equipment Control) international standard.

[0017] In one embodiment, the command signal is characterized in that it includes TP (transponder) information, which is channel selection information for selecting a specific channel, including information on a satellite transmitting a broadcast signal corresponding to the specific channel, a polarization direction of a satellite signal corresponding to the specific channel, and information on a frequency band corresponding to the specific channel.

[0018] In one embodiment, the control unit is characterized in that, when a command signal of a channel selected according to the preset order is transmitted to the switch and, as a result of the determination of whether or not the channel is fixed, channel fixation for the selected channel is possible, information on the selected channel is stored as channel information and information on the changed delay time is stored, and whenever channel fixation is possible according to the transmitted command signal, the stored delay time is updated with information on the delay time between the command signal of the channel for which channel fixation is possible and the command signal transmitted previously.

[0019] In one embodiment, the control unit is characterized in that, when a continuous channel switching request is received, it sequentially transmits a plurality of command signals according to the continuous channel switching request to the switch according to information on a previously stored delay time.

[0020] In one embodiment, the preset function is channel tuning, and the control unit performs the channel tuning when a preset condition is satisfied, and the preset condition includes a case where there is no pre-stored channel information, at least a part of a satellite broadcast program is updated, at least one of the switch and the satellite antenna is changed, and a case where the channel is not fixed for a satellite broadcast reception signal according to a channel according to the pre-stored channel information.

[0021] In one embodiment, the satellite broadcast receiver is characterized by including a TV system.

[0022] In order to achieve the above or other purposes, according to one aspect of the present invention, a method for controlling a satellite broadcasting receiver according to an embodiment of the present invention, when transmission of command signals corresponding to a plurality of channels is requested, a step of checking whether a preset delay time has elapsed after a second command signal of a second channel selected before a first channel selected in a preset order is transmitted to a switch for selecting a satellite broadcasting signal received by a satellite antenna, if the delay time has elapsed, a step of transmitting a first command signal including channel selection information of the first channel to the switch, a step of determining whether channel fixation is possible for a satellite broadcasting signal received from the switch according to the first command signal, a step of storing channel information of the first channel if channel fixation is possible as a result of the determination of whether channel fixation is possible, a step of changing the delay time and checking whether the delay time has elapsed according to the changed delay time, a step of transmitting the first command signal to the switch, and a step of re-performing the step of determining whether channel fixation is possible. It is characterized by including.

[0023] In one embodiment, the step of determining whether the channel fixation is possible includes the step of oscillating a local signal having a local frequency according to the frequency of the first channel, the step of mixing a satellite broadcast signal received from the switch according to the first command signal with the local signal, the step of modulating and decoding a satellite broadcast signal whose frequency band is converted by being mixed with the local signal, and the step of determining whether the channel fixation is possible according to whether a bit string corresponding to a preset channel tuning frame is included in a data stream according to the decoded satellite broadcast signal.

[0024] In one embodiment, the delay time is set to a preset minimum delay time, and is characterized in that it gradually increases in units of preset time whenever the delay time is changed.

[0025] The effects of the satellite broadcasting receiver and the satellite broadcasting receiver control method according to the present invention are described as follows.

[0026] According to at least one of the embodiments of the present invention, the present invention has the effect of minimizing the channel switching time by detecting a command interval delay optimized according to the performance of a switch and transmitting a command signal according to channel switching according to the detected command interval delay.

[0027] FIG. 1 is an exemplary diagram illustrating a satellite broadcasting receiving system according to an embodiment of the present invention.

[0028] FIG. 2a and FIG. 2b are block diagrams illustrating the configuration of a satellite broadcasting receiver according to an embodiment of the present invention.

[0029] FIG. 3 is a flowchart illustrating the operation process of a satellite broadcasting receiver according to an embodiment of the present invention.

[0030] FIG. 4 is a flowchart illustrating in more detail the operation process of FIG. 3 for determining whether channel fixation is possible in a satellite broadcasting receiver according to an embodiment of the present invention.

[0031] FIGS. 5A and 5B are exemplary diagrams each showing an example of transmitting a plurality of command signals in a conventional satellite broadcast receiver and a satellite broadcast receiver according to an embodiment of the present invention.

[0032] It should be noted that the technical terms used herein are used merely to describe specific embodiments and are not intended to limit the present invention. Furthermore, singular expressions used herein include plural expressions unless the context clearly dictates otherwise. The suffixes "module" and "part" used in the following description for components are assigned or used interchangeably solely for the convenience of writing the specification, and do not in themselves have distinct meanings or roles.

[0033] In this specification, the terms “comprises” or “includes” should not be construed to necessarily include all of the components or steps described in the specification, and some of the components or steps may not be included, or additional components or steps may be included.

[0034] In addition, when describing the technology disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the technology disclosed in this specification, the detailed description is omitted.

[0035] In addition, the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention. In addition, not only each embodiment described below, but also a combination of embodiments may correspond to the spirit and technical scope of the present invention as modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

[0036] FIG. 1 is an exemplary diagram illustrating a satellite broadcasting receiving system according to an embodiment of the present invention.

[0037] Referring to FIG. 1, a satellite broadcasting reception system according to an embodiment of the present invention can be formed by including a satellite antenna (10) equipped with an LNB (Low Noise Blockdown converter), a switch (20) connected to the satellite antenna (10) and controlling the elevation and azimuth of the satellite antenna, and a plurality of different satellite broadcasting receivers (31, 32, 33, 34, hereinafter collectively referred to as 30) connected to the switch.

[0038] Here, the satellite antenna (10) is an antenna that receives satellite signals and may be a parabolic antenna. In addition, an LNB, which is a frequency conversion device that lowers the satellite frequency to the frequency of each satellite broadcasting receiver (e.g., set-top box), may be provided. In addition, the satellite antenna (10) may change its elevation and azimuth angles according to the control of a switch, and may receive satellite signals according to different elevation or azimuth angles and different frequencies.

[0039] Meanwhile, the switch (20) can receive broadcast signals of different channels according to the satellite signal received from the satellite antenna (10). The switch (20) controls the receiving angle and receiving direction of the satellite antenna (10) according to the command received from the satellite broadcast receiver (30), and can search for each frequency within a preset range and search for the channel provided for each TP (Transponder).

[0040] Each TP may have different reception angles, reception directions, and at least one of the frequencies of the satellite antenna (10). For example, the input signals from the satellite antenna (10) may be classified into different combinations of information about the satellite being received, the polarization direction of the satellite signal (e.g., horizontal or vertical), and the frequency band (e.g., high-frequency band or low-frequency band), thereby forming different TPs. For example, when the input signals of the satellite antenna (10) are classified according to a combination of two different satellite signal polarization directions and two different frequency bands as described above, four types of satellite signal inputs may be formed for one satellite. In addition, one or more channels may be assigned to each TP. In this case, different frequencies may be assigned to each channel assigned to the same TP within the frequency band of the same band.

[0041] The satellite broadcast receiver (30) may include information about satellite signal inputs corresponding to each TP in the form of a list. Furthermore, the list of satellite signal inputs corresponding to each TP may include a list of channels corresponding to each TP. Hereinafter, the information about satellite signal inputs corresponding to each TP and the list of channels assigned to each TP will be referred to as a TP list.

[0042] Meanwhile, when a satellite broadcasting signal selection signal according to the DiJEC international standard is received from the satellite broadcasting receiver (30), the satellite broadcasting signal according to the received selection signal can be received from the satellite antenna (10). In this case, the satellite broadcasting receiver (30) can control the drive motor of the satellite antenna to direct the elevation or azimuth according to the currently selected TP by controlling the satellite antenna (10) if necessary, for example, when a TP different from the currently set elevation or azimuth of the satellite antenna (10) is selected. In this case, the satellite broadcasting signal selection signal may be a channel selection signal for selecting a channel assigned to a specific TP.

[0043] Here, the channel selection signal may be transmitted from the satellite broadcast receiver (30). For this purpose, the satellite broadcast receiver (30) may include the TP list in its memory, and may transmit a signal including information on a TP corresponding to a channel selected based on the TP list to the switch. In this case, the signal including information on a TP corresponding to the selected channel may be a signal for controlling the switch (20), and may be a command signal for controlling the switch (20) according to the DiJEC international standard.

[0044] Meanwhile, the satellite broadcast receiver (30) may be a set-top box placed in each household or a TV system directly connected to the switch (20). In this case, the TV system may include the functions of the set-top box. Accordingly, it may include functions such as channel tuning as well as a content playback function that demodulates and decodes broadcast signals and plays them back.

[0045] The above channel tuning function may be a function that searches for channel selection information corresponding to each channel when the channel information of each broadcast channel changes, such as when a new satellite broadcast receiver (30) is installed or the broadcast system is updated. The channel tuning function may be called auto tuning or the like, and may be performed according to a user's selection or when preset conditions, such as the broadcast system or channel information update, are met.

[0046] Meanwhile, the satellite broadcast receiver (30) may transmit channel selection information corresponding to the selected channel to the switch (20) when a specific channel is selected by the user or according to the channel tuning function. The channel selection information is information of the TP corresponding to the selected channel, and may include information of a combination according to a satellite signal input corresponding to the selected channel, for example, a polarization direction (e.g., horizontal or vertical) of a specific satellite signal and a specific frequency band (e.g., high frequency band or low frequency band). In addition, the channel selection information may be input to the switch (20) as a command signal, and in response to transmission of the command signal, a satellite broadcast signal corresponding to the satellite signal input corresponding to the selected channel may be received by the satellite broadcast receiver (30).

[0047] Then, the satellite broadcast receiver (30) can demodulate the received satellite broadcast signal based on the local frequency corresponding to the selected channel. Then, the demodulated satellite broadcast signal can be decoded into a data stream, and whether channel fixation is possible can be detected from the decoded data stream. If channel fixation is possible, information on the selected channel can be stored as channel information. Then, the decoded data stream can be reproduced to output video signals and / or audio signals according to the received satellite broadcast signal through the display unit and / or audio output unit.

[0048] Meanwhile, when a user continuously switches channels, or when the channel tuning function is performed, a plurality of command signals including different channel selection information can be continuously transmitted to the switch (20).

[0049] Meanwhile, when multiple command signals are transmitted sequentially in this manner, the switch (20) can process the multiple command signals in the order in which they are received. However, if another command signal is received before the processing of the command signal received first is completed, an error may occur in the control of the satellite antenna (10) as different command signals are processed together. Accordingly, the satellite broadcast receiver (30) transmits another command signal after a preset delay time has elapsed when a command signal is transmitted, and thus a delay time may occur between command signals.

[0050] Meanwhile, the command signal processing time of the switch (20) may vary depending on the performance of the switch (20) and / or the satellite antenna (10). For example, if the performance of the switch (20) and / or the satellite antenna (10) is poor and thus a long time is required to receive a satellite broadcast signal according to a combination of satellite signal inputs according to channel selection information (TP information) included in the command signal, the command signal processing time may be long. On the other hand, if the performance of the switch (20) and / or the satellite antenna (10) is excellent and thus a satellite broadcast signal according to a combination of satellite signal inputs according to channel selection information (TP information) included in the command signal can be received within a very short time, the command signal processing time may be very short. Therefore, if the performance of the switch (20) and / or the satellite antenna (10) is excellent and the processing time of the command signal is very short, it goes without saying that the satellite broadcast signal of the selected channel can be correctly received even if the delay time between the command signals is shortened.

[0051] Accordingly, the satellite broadcast receiver (30) according to an embodiment of the present invention detects the command signal processing time of the switch (20) when a preset condition is met, and sets the delay time between the command signals according to the detected command signal processing time, thereby enabling the channel switching time to be shortened.

[0052] Figures 2a and 2b are block diagrams showing the configuration of a satellite broadcasting receiver (30) according to an embodiment of the present invention.

[0053] First, referring to FIG. 2A, a satellite broadcast receiver (30) according to an embodiment of the present invention may be configured to include a control unit (100), an interface unit (110), a tuning unit (120), a memory (130), and an input unit (140) connected to and controlled by the control unit (100). In addition, when the satellite broadcast receiver (30) includes a TV system, it may be configured to include an output unit (150) capable of outputting video signals and audio signals according to a data stream demodulated and decoded through the tuning unit (120). Meanwhile, the components illustrated in FIG. 2A are not essential for implementing the satellite broadcast receiver (30), and thus, the satellite broadcast receiver (30) described in this specification may have more or fewer components than the components listed above.

[0054] More specifically, among the above components, the interface unit (110) is connected to the switch (20) and can transmit various control signals to the switch (20) or receive satellite broadcast signals from the switch (20). To this end, the interface unit (110) may include a transmitter (111) equipped with a transmission interface capable of transmitting a command signal to the switch (20) and a receiver (112) equipped with a reception interface capable of receiving a satellite broadcast signal received from the switch (20). Here, it goes without saying that the transmitter (111) and the receiver (112) may be formed as a single interface.

[0055] And the tuning unit (120) can build a broadcast viewing environment so that a satellite broadcast signal corresponding to a selected channel can be received. To this end, when a satellite broadcast signal is received, the tuning unit (120) can demodulate and decode the received satellite broadcast signal into a data stream, and determine whether a channel is locked from the decoded data stream. And, depending on whether channel locking is possible, information on the selected channel can be stored as channel information. To this end, the tuning unit (120) can include an oscillator (121), a demodulator (122), a decoder (123), and a channel lock detection unit (124), as shown in FIG. 2b.

[0056] First, the oscillator (121) can oscillate a local frequency according to the currently selected channel. The oscillator (121) can include a PLL (Phase Locked Loop) and the PLL register, and can oscillate a signal having a fixed frequency according to a value set in the PLL register. In addition, the local frequency oscillated by the oscillator (121) and the frequency of the satellite broadcast signal received from the switch (20) can be mixed to generate a signal having a preset intermediate frequency.

[0057] Here, the oscillator (121) can oscillate different local frequencies according to the selected channel so as to generate a signal having a fixed intermediate frequency according to the control of the control unit (100). For example, if the frequency of the satellite broadcast signal corresponding to the currently selected first channel is 860 MHz and the fixed intermediate frequency is 10 MHz, the oscillator (121) can oscillate the local frequency so that the difference between the local frequency and the frequency of the first channel (local frequency - frequency of the satellite broadcast signal) becomes the intermediate frequency of 10 MHz according to the control of the control unit (100). Therefore, in this case, the oscillator (121) can oscillate a signal having a local frequency of 870 MHz.

[0058] However, for example, if the frequency of the satellite broadcast signal corresponding to the currently selected second channel is 868 MHz, the oscillator (121) can oscillate the local frequency so that the difference between the local frequency and the frequency of the second channel becomes the intermediate frequency of 10 MHz under the control of the control unit (100). Accordingly, if the second channel is selected, the oscillator (121) can oscillate a signal having a local frequency of 878 MHz. That is, as the frequency of the satellite broadcast signal of the selected channel changes, signals having different local frequencies can be oscillated to generate a fixed intermediate frequency.

[0059] Then, the demodulator (122) can demodulate the satellite broadcast signal converted into a signal having the intermediate frequency. Then, the carrier wave can be removed, and accordingly, the satellite broadcast signal can be converted into a baseband signal. And the decoder (123) can decode the satellite broadcast signal converted into the baseband signal.

[0060] The above satellite broadcast signal may be data encoded according to a preset coding method. For example, video data may be data encoded according to a method such as H.265 / MPEG-H HEVC, H.264 / MPEG-4 AVC, H.262 / MPEG-2, etc., and audio data may be data encoded according to a coding method such as MPEG-H, HE-AAC, AAC, MP3, etc. Accordingly, the decoding unit (123) may decode the satellite broadcast signal into a data stream including video data and / or audio data according to the method in which the satellite broadcast signal is encoded.

[0061] Meanwhile, the satellite broadcast signal converted into the data stream may include a channel synchronization frame containing channel sync information. The channel lock detection unit (124) of the tuning unit (120) can detect the channel synchronization frame from the data stream. It can then be determined whether the bit sequence of the detected channel synchronization frame matches a preset bit sequence.

[0062] As a result of the above determination, it can be determined whether the satellite broadcast signal has been correctly decoded into a data stream depending on whether the bit string included in the channel tuning frame matches the preset bit string. In addition, if the bit string included in the channel tuning frame matches the preset bit string, the control unit (100) can determine that a data stream corresponding to the broadcast content of the selected channel is received from the satellite broadcast signal received according to the channel selection information. Accordingly, the control unit (100) can store information on the currently selected channel as channel information (channel fixation).

[0063] On the other hand, if the bit string included in the above channel tuning frame does not match the preset bit string, the control unit (100) may determine that the data stream corresponding to the broadcast content of the selected channel has not been received from the satellite broadcast signal received according to the channel selection information. Accordingly, the control unit (100) may not store information on the currently selected channel.

[0064] And the input unit (140) is for inputting information input from a user and may be equipped with at least one input means for receiving a user's input. For example, the input unit (140) may include a plurality of buttons or mechanical input means such as a jog wheel or a switch or a touch input means. In addition, the input unit (140) may include a remote controller formed to be detachable from the satellite broadcast receiver (30) as an input means. In this way, when the input unit (140) includes a remote controller, the remote controller and the input unit (140) may be connected to each other through a preset short-range communication method.

[0065] In addition, the satellite broadcast receiver (30) may include an output unit (150) capable of playing video content and audio content according to the received satellite broadcast signal. For example, the satellite broadcast receiver (30) may be formed integrally with a TV system including a display unit capable of playing video content and an audio output unit capable of playing audio content, in which case the TV system may have a configuration corresponding to the output unit (150).

[0066] Meanwhile, the memory (130) can store data supporting various functions of the satellite broadcast receiver (30). The memory (130) can store a plurality of application programs (or applications) running on the satellite broadcast receiver (30), data for the operation of the satellite broadcast receiver (30), and commands. At least some of these application programs can be downloaded from an external server via wireless communication. In addition, at least some of these application programs can exist on the satellite broadcast receiver (30) from the time of shipment for the basic functions of the satellite broadcast receiver (30) (e.g., receiving satellite broadcast signals, transmitting command signals, etc.).

[0067] As data for supporting the function of the satellite broadcast receiver (30) in this way, the memory (130) may include information for generating a command signal. In this case, the information for generating the command signal may include a TP list, which is channel selection information for each channel, and a list including TP for each channel and satellite signal input corresponding to each TP, for example, information on a specific satellite, information on a combination according to the polarization direction (e.g., horizontal or vertical) and a specific frequency band (e.g., high frequency band or low frequency band) of the satellite signal, and information on a frequency corresponding to each channel. Hereinafter, an area on the memory (130) of the satellite broadcast receiver (30) where the TP list is stored will be referred to as a TP list information storage unit (131).

[0068] In addition, the memory (130) can store information on the channel set in the tuning unit (120). For example, if the tuning unit (120) successfully fixes a channel, the control unit (100) can store information on the fixed channel as the channel information. Hereinafter, an area on the memory (130) where channel information on the fixed channel is stored will be referred to as a channel information storage unit (132).

[0069] Meanwhile, the control unit (100) of the satellite broadcast receiver (30) according to an embodiment of the present invention can typically control the overall function of the satellite broadcast receiver (30). For example, when a specific channel is selected, the control unit (100) can search for channel selection information corresponding to the selected channel from the TP list and transmit a command signal including the searched channel selection information to the switch (20). Then, the satellite broadcast signal received from the switch (20) can be demodulated and decoded through the tuning unit (120), and the decoded satellite broadcast signal can be output as a data stream to a TV system for playback. Alternatively, when the satellite broadcast receiver (30) is capable of reproducing the decoded satellite broadcast signal, i.e., when it includes a TV system, the video signal and audio signal according to the data stream of the decoded satellite broadcast signal can be output through the display unit and audio.

[0070] Meanwhile, the control unit (100) can search for a channel when a user requests or when a channel tuning function is executed. To this end, the control unit (100) can transmit a plurality of command signals, each containing different channel selection information, to the switch (20), and, based on the result of determining whether a satellite broadcast signal received from the switch (20) is channel-fixed, can store information on channels that can be fixed as channel information of the searched channel in the memory (130), more specifically, in the channel information storage unit (132).

[0071] Here, when transmitting the plurality of command signals, the control unit (100) can set a command interval delay (CID, Command Interval Delay) between command signals of a preset minimum value. Here, the command interval delay time having the minimum value may be a minimum time according to a preset international standard (e.g., DIEZC).

[0072] And the control unit (100) can detect whether channel fixation of the currently selected channel is possible according to the delay time between command signals of the currently set minimum value. In this case, if the performance of the switch (20) and / or the satellite antenna (10) is sufficient, that is, the switch (20) and / or the satellite antenna (10) can process the received command signal within the delay time between the command signals of the minimum value. Therefore, if a command signal including changed channel selection information is received after the delay time between the command signals of the minimum value has elapsed, the satellite broadcast signal according to the changed channel can be transmitted to the satellite broadcast receiver (30) through the switch (20).

[0073] Meanwhile, when a command signal is transmitted, the control unit (100) can control the oscillator (121) to oscillate a local frequency for generating a preset intermediate frequency according to the frequency of the selected channel. Then, as the command signal such as parsing is processed, a satellite broadcast signal corresponding to the selected channel can be received, and an intermediate frequency of the preset frequency band (e.g., 10 MHz) can be generated according to the oscillated local frequency. Then, the satellite broadcast signal corresponding to the selected channel is demodulated and decoded by the demodulator (122) and the decoder (123), and a bit string corresponding to the bit string of the preset channel tuning frame can be detected from the decoded data stream. Accordingly, the channel can be fixed, and the control unit (100) can store information on the fixed channel as channel information.

[0074] Therefore, if the switch (20) and / or satellite antenna (10) can process the received command signal within the delay time between command signals, the satellite broadcast signal corresponding to the changed channel can be demodulated and decoded whenever the channel is changed, and information on the changed channel can be stored as channel information.

[0075] However, if the delay time between command signals is not sufficient compared to the performance of the switch (20) and / or satellite antenna (10), the reception of subsequent command signals may be delayed. Accordingly, some of the subsequently received command signals may not be received by the switch (20).

[0076] In this way, if a portion of the command signal is not received, parsing of the received command signal may not occur. Then, the switch (20) cannot process the currently received command signal, and accordingly, the satellite broadcast signal corresponding to the previously processed command signal, i.e., the satellite broadcast signal of the previous channel, may be received by the satellite broadcast receiver (30) through the switch (20).

[0077] However, as described above, when a command signal is transmitted, the control unit (100) can control the oscillator (121) to oscillate a local frequency for generating a preset intermediate frequency according to the frequency of the currently selected channel, i.e., the changed channel. Accordingly, when the channel is changed from a first channel (e.g., 860 MHz) to a second channel (e.g., 868 MHz), the control unit (100) controls the oscillator (121) to oscillate a first local frequency (e.g., 870 MHz) corresponding to the first channel, and when a command signal for selecting the second channel is transmitted, the oscillator (121) can be controlled to oscillate a second local frequency (e.g., 878 MHz) corresponding to the second channel.

[0078] However, as described above, if the command signal for selecting the second channel is not processed due to insufficient delay time between command signals, the switch (20) may receive a satellite broadcast signal according to the channel selection information before the change, i.e., a satellite broadcast signal according to the first channel, and transmit the satellite broadcast signal to the satellite broadcast receiver (30) as a valid command signal is not received. Accordingly, even though the command signal for selecting the second channel has been transmitted, a satellite broadcast signal corresponding to the first channel (e.g., 860 MHz) may be received by the satellite broadcast receiver (30).

[0079] However, as described above, when a command signal for selecting a second channel is transmitted, the control unit (100) controls the oscillator (121) to generate a local frequency for decoding the second channel. Accordingly, the oscillator (121) oscillates the second local frequency (e.g., 878 MHz), and accordingly, an abnormal intermediate frequency (878 MHz - 860 MHz = 18 MHz) that deviates from a preset intermediate frequency (e.g., 10 MHz) based on the received satellite broadcast signal (860 MHz) and the second local frequency (878 MHz) is generated.

[0080] Then, demodulation and decoding are performed according to the above-mentioned abnormal intermediate frequency, and a data stream including data bit strings according to the above-mentioned abnormal intermediate frequency can be generated. Therefore, a bit string corresponding to a channel tuning frame may not be detected from the data stream, and channel locking may become impossible.

[0081] Meanwhile, if it is determined that channel fixation of the currently selected channel is impossible, the control unit (100) can increase the delay time between the currently set command signals by a preset time. And when the delay time between the command signals increased by the preset time from the time the command signal is transmitted has elapsed, the command signal of the currently selected channel can be transmitted to the switch (20) again. And the oscillator (121) can be controlled again to oscillate a local frequency according to the currently selected channel, and whether channel fixation is possible can be determined again from the data stream of the decoded and demodulated satellite broadcast signal. And if channel fixation is possible, the delay time between the currently set command signals can be stored, and when the stored delay time has elapsed since the command signal was transmitted, another channel according to the next turn can be selected, and a command signal including channel selection information of the selected channel can be transmitted to the switch (20).

[0082] Therefore, the control unit (100) of the satellite broadcast receiver (30) according to an embodiment of the present invention first sets the delay time between command signals having a preset minimum value, and then gradually increases the delay time between command signals depending on whether channel fixation is possible based on the currently set delay time between command signals. By performing this process for each channel for which channel tuning is performed, the optimal delay time between command signals for which all channels for which channel tuning is performed can be fixed can be detected. The detected delay time between command signals can be stored in the memory (130), and the stored delay time between command signals can be applied whenever command signals according to channel switching are transmitted. Hereinafter, an area on the memory (130) where the delay time between command signals is stored will be referred to as a CID information storage unit (133).

[0083] Therefore, the satellite broadcast receiver (30) according to an embodiment of the present invention can detect the minimum delay time between command signals that allows the correct satellite broadcast signal to be received according to the selected channel depending on the performance of the switch (20) and / or the satellite antenna (10). Accordingly, the time between the transmission of a command signal and the transmission of the next command signal can be shortened, and consequently, the channel switching time of multiple channels can be shortened.

[0084] Meanwhile, the satellite broadcast receiver (30) according to an embodiment of the present invention can perform channel switching according to the stored delay time whenever channel switching is requested. That is, when continuous channel switching is requested due to continuous channel switching by a user, the control unit (100) can sequentially transmit a plurality of command signals according to the continuous channel switching to the switch (20) according to the delay time between command signals stored in the CID information storage unit (133). In this case, the delay time stored in the CID information storage unit (133) may be the minimum delay time between command signals that allows channel fixation. Therefore, even if it is not channel tuning, when continuous channel switching is requested by a user, the time required for the channel switching can be shortened.

[0085] FIG. 3 is a flowchart illustrating an operation process for detecting an optimal delay time between command signals in a satellite broadcast receiver (30) according to an embodiment of the present invention described above.

[0086] First, the control unit (100) of the satellite broadcast receiver (30) according to an embodiment of the present invention can execute a channel tuning function when a user selection or a preset condition is satisfied. Then, when the channel tuning function is executed, the operation process of FIG. 3 can be executed. In this case, the preset condition may be a case where there is no pre-stored channel information. For example, when the satellite broadcast receiver (30) is first installed, there may be no pre-stored channel information. Alternatively, the preset condition may be satisfied when the satellite broadcast channel information is changed due to an update of a satellite broadcast program, or when the switch (20) or satellite antenna (10) is changed, such as when the broadcast system, such as the switch (20) or satellite antenna (10), is upgraded. Alternatively, the preset condition may be satisfied when the channel is not fixed from a satellite broadcast signal received according to the channel information stored in the channel information storage unit (132).

[0087] When the channel tuning function is executed in this way, the control unit (100) can set a delay time between command signals having a preset minimum value (S300). Then, the first channel can be selected among the channels according to the TP list (S302).

[0088] And from the TP list, channel selection information capable of receiving a satellite broadcast signal according to the currently selected first channel, such as TP information including the name of the satellite, polarization direction of the satellite signal (e.g. horizontal or vertical) and frequency band (e.g. high frequency band or low frequency band), and frequency information of the selected channel can be detected (S304).

[0089] And after the command signal is transmitted, it can be checked whether the currently set delay time between command signals has elapsed (S306). And if the delay time between command signals has elapsed, a command signal including channel selection information of the currently selected channel can be transmitted to the switch (20) (S308).

[0090] In this case, if the currently selected channel is the first channel to be tuned since the channel tuning function was executed (the first channel), there may be no previously transmitted command signal. Therefore, the control unit (100) may skip step S306 and proceed directly to step S308.

[0091] When a command signal is transmitted to the switch (20), the control unit (100) can determine whether channel fixation is possible for the satellite broadcast signal received through the switch (20) (S310). In order to determine whether channel fixation is possible in the step S310, the control unit (100) can generate a signal having a local frequency according to the currently selected channel and mix the generated signal with the received satellite broadcast signal. Then, the signal generated through the mixing can be demodulated and decoded, and whether the decoded signal is capable of channel fixation can be determined.

[0092] Referring to FIG. 4 below, the process of determining whether a channel is fixed in step S310 will be examined in more detail.

[0093] If the determination result of the step S310 above is that channel fixation is not possible, the control unit (100) can increase the delay time between the currently set command signals by a preset time (S312). Then, the control unit (100) can proceed to step S306 to check whether the delay time between the command signals increased by the preset time has elapsed from the time the previous command signal was transmitted. Then, if the delay time between the command signals increased by the preset time has elapsed from the time the previous command signal was transmitted, the control unit can proceed to step S308 to retransmit to the switch a command signal including channel selection information of the currently selected channel, i.e., the channel on which the channel was not fixed. Then, the control unit can proceed to step S310 to check again whether channel fixation is possible.

[0094] Accordingly, if channel locking is not achieved for the currently selected channel, the process from step S306 to step S312 may be repeated. In addition, each time step S312 is performed again, the delay time between command signals may be increased by a preset amount of time.

[0095] And, as a result of the determination in step S310, if it is possible to fix the channel for the satellite broadcast signal received from the switch (20) while the delay time between the currently set command signals is set, the control unit (100) can store the information of the currently selected channel as channel information in the channel information storage unit (132) (S314).

[0096] And the control unit (100) can check whether tuning for all channels according to the TP list has been completed (S316).

[0097] If the result of the check in step S316 indicates that tuning for all channels has been completed, the control unit (100) can terminate the channel tuning process illustrated in FIG. 3. However, if the result of the check in step S310 indicates that tuning for all channels according to the TP list has not been completed, the channel next to the channel for which the current channel information is stored can be selected as the channel for which tuning is to be performed (S318).

[0098] Then, the control unit (100) can proceed to step S304 and detect channel selection information according to the currently selected channel, i.e., the channel next to the channel in which channel information is stored, from the TP list. Then, the process after step S304 can be performed again.

[0099] Therefore, if the channel information of the first channel is stored in step S314, the control unit (100) can select the channel to be tuned, i.e., the second channel, according to the following sequence. Then, the control unit (100) can proceed to step S304 to detect the channel selection information of the currently selected second channel. Then, the control unit can proceed to step S306 to determine whether the currently set delay time between command signals has elapsed after the command signal according to the first channel is transmitted. If the delay time between command signals has elapsed, the control unit can proceed to step S308 to transmit a command signal including the channel selection information of the second channel to the switch (20). Then, the control unit (100) can proceed to step S310 to receive the satellite broadcast signal transmitted from the switch (20) and determine whether channel fixation is possible. In this case, in step S310, the received satellite broadcast signal can be demodulated and decoded according to the local frequency according to the second channel to determine whether channel fixation is possible.

[0100] In this case, as described above, if the delay time between command signals is not sufficient compared to the performance of the switch (20) and / or the satellite antenna (10), some of the command signals for selecting the second channel may not be received by the switch (20). Then, the command signal may not be parsed, and accordingly, the satellite broadcast signal received by the switch (20) may not be changed. Therefore, the satellite broadcast signal according to the previously received command signal, i.e., the command signal corresponding to the first channel, may continue to be received. However, since the current oscillator (121) oscillates a signal having a local frequency according to the frequency of the second channel, the demodulation of the received satellite broadcast signal may not be performed correctly. Therefore, the channel fixation in step S310 may not be performed.

[0101] Then, the control unit (100) can proceed from step S310 to step S312 to increase the delay time between command signals. If the delay time between command signals is sufficient compared to the performance of the switch (20) and / or the satellite antenna (10), the command signal for selecting the second channel can be completely received and processed by the switch (20). Accordingly, the switch (20) can receive the satellite broadcast signal corresponding to the second channel and transmit the satellite broadcast signal corresponding to the second channel to the satellite broadcast receiver (30). Accordingly, a satellite broadcast signal having a preset intermediate frequency can be generated and demodulated and decoded according to the local frequency oscillated by the oscillating unit (121). If bit strings corresponding to the preset channel tuning frame are detected from the decoded data stream (channel locking), the control unit (100) can proceed to step S314 to store the channel information of the second channel.

[0102] And when the channel information of the second channel is stored, the control unit (100) can proceed to steps S316 and S318 to select a channel according to the next sequence, i.e., the third channel. And, in the same manner as described above, whether the channel is fixed can be determined and the delay time between command signals can be increased based on the determination result.

[0103] In this case, if channel fixation is not achieved, the control unit (100) can gradually increase the delay time between command signals and update the delay time stored in the CID information storage unit (133) whenever channel fixation is possible. Therefore, when tuning for all channels is completed, the optimal delay time between command signals for channel fixation can be set for all channels. Then, the control unit (100) can store the currently set delay time between command signals, and when a command signal is transmitted in accordance with a future channel switch, the command signal can be transmitted to the switch (20) according to the delay time between the command signals. Accordingly, when multiple channel switches occur due to user selection, etc. as well as channel tuning, the time required for each channel switch can be shortened.

[0104] Meanwhile, FIG. 4 is a flowchart illustrating in more detail the operation process in step S310 of FIG. 3 for determining whether channel fixation is possible in a satellite broadcast receiver (30) according to an embodiment of the present invention.

[0105] Referring to FIG. 4, the control unit (100) of the satellite broadcast receiver (30) according to the embodiment of the present invention can, when a command signal including channel selection information of the currently selected channel is transmitted to the switch (20) in step S308, generate a signal having a local frequency for generating a preset intermediate frequency, i.e., a local signal, according to the frequency of the currently selected channel (S400). In this case, the control unit (100) can control the oscillation unit (121) to oscillate a local signal having a frequency higher than the frequency of the currently selected channel by the preset intermediate frequency. In addition, the control unit (100) can mix the oscillated local signal with the satellite broadcast signal received from the switch (20) (S402).

[0106] Accordingly, if a satellite broadcast signal having a frequency of the currently selected channel is received from the switch (20), a satellite broadcast signal having a preset intermediate frequency can be generated depending on the difference between the frequency of the local signal (local frequency) and the frequency of the received satellite broadcast signal. However, if a satellite broadcast signal having a frequency different from the frequency of the currently selected channel is received from the switch (20), a signal having a frequency other than the preset intermediate frequency can be generated as a result of the mixing.

[0107] When the local signal and the satellite broadcast signal are mixed in step S402, the control unit (100) can demodulate the mixed satellite broadcast signal into a baseband signal (S404). In this case, the control unit (100) can perform error correction according to a preset method on the satellite broadcast signal demodulated into the baseband signal. For example, the control unit (100) can correct errors that may occur during the mixing and demodulation process through error correction according to the FEC (Forward Error Correction) method.

[0108] And the control unit (100) can decode the satellite broadcast signal demodulated into a baseband signal into a data stream including video content and audio content according to a preset encoding method (S406).

[0109] And the control unit (100) can detect a channel synchronization frame from the decoded data stream (S408). In this case, the S408 step may be a step of detecting whether the decoded data stream includes a bit string corresponding to a preset channel synchronization frame.

[0110] For example, if a satellite broadcast signal having a preset intermediate frequency is generated in step S402, it can be decoded into a data stream including bit streams according to video content and audio content and data of the currently selected channel. Therefore, the decoded data stream can include a bit stream corresponding to the preset channel tuning frame. However, if a signal having a frequency other than the intermediate frequency is generated in step S302, a meaningless bit stream in which 1s and 0s are mixed can be formed depending on the difference in the frequencies. Therefore, even if demodulation and decoding are performed, the decoded data stream may not include a bit stream corresponding to the preset channel tuning frame.

[0111] Accordingly, if, as a result of the check in step S408, a bit string corresponding to a channel tuning frame is detected from the data stream, the control unit (100) can determine that the currently received, demodulated, and decoded satellite broadcast signal is capable of channel fixation according to the currently selected channel (S410). Then, the control unit (100) can determine that channel fixation is possible in step S310 of FIG. 3 and proceed to S314 of FIG. 3 to store information on the currently selected channel as channel information.

[0112] On the other hand, if the check result of step S408 shows that a bit string corresponding to a channel tuning frame is not detected from the data stream, the control unit (100) can determine that the currently received, demodulated, and decoded satellite broadcast signal does not allow channel fixation according to the currently selected channel (S412). Then, the control unit (100) can determine that channel fixation is not possible in step S310 of FIG. 3 and proceed to step S312 of FIG. 3 to increase the delay time between command signals by a preset time. Then, a command signal for selecting the currently selected channel is retransmitted according to the increased delay time between command signals, and whether or not channel fixation is possible can be determined again according to the transmitted command signal.

[0113] FIGS. 5A and 5B are exemplary diagrams each showing an example of transmitting a plurality of command signals in a conventional satellite broadcast receiver and a satellite broadcast receiver according to an embodiment of the present invention.

[0114] Meanwhile, when the above command signal is transmitted to the switch (20), the satellite broadcast receiver () can transmit a preset tone burst signal to the switch (20). In this case, each time the command signal is transmitted, the transmission of the tone burst signal can be stopped for a preset delay time between the command signals to distinguish between the tone burst signal and the command signal. The following Figures 5a and 5b illustrate examples of such a case.

[0115] First, FIG. 5A illustrates an example of a tone signal in which multiple command signals are sequentially transmitted to a switch according to channel tuning, etc. in a typical satellite broadcast receiver. In this case, while a tone burst signal (500) is transmitted from the satellite broadcast receiver to the switch, a command signal (510) containing channel selection information of a channel selected for channel tuning may be transmitted. In this case, a delay time (520) between the command signals may be included to prevent confusion between the tone burst signal (500) and the command signal (520).

[0116] In this case, if the delay time (520) between command signals is insufficient as described above, channel fixation may not be achieved according to the selected channel. However, since the satellite broadcast receiver (30) does not know the performance of the switch (20) and / or the satellite antenna (10), the delay time (520) between command signals in a typical satellite broadcast receiver can be set to a sufficiently long time so that channel fixation can be achieved even when a switch (20) and / or a satellite antenna (10) with poor performance is connected. Therefore, the delay time (520) between command signals may be formed to be long, as shown in FIG. 5A.

[0117] On the other hand, the satellite broadcast receiver (30) according to an embodiment of the present invention can first set the minimum delay time between command signals as described above and determine whether channel fixation of the selected channel is possible based on the set delay time between command signals. Then, by gradually increasing the delay time between command signals based on the determination result, the minimum delay time (560) between command signals at which channel fixation of the selected channel can be achieved can be detected depending on the performance of the switch (20) and / or satellite antenna (10) connected to the satellite broadcast receiver (30).

[0118] Accordingly, even if the length of the tone burst signal (500) and the length of the command signal (510) are the same, as shown in Fig. 5b, the same number of command signals can be transmitted to the switch (20) within a shorter time. Accordingly, when channel switching occurs continuously, such as during channel tuning, there is an effect that the time required for the channel switching can be significantly shortened.

[0119] The present invention described above can be implemented as computer-readable code on a medium in which a program is recorded. The computer-readable medium includes all types of recording devices that store data that can be read by a computer system. Examples of computer-readable media include hard disk drives (HDDs), solid state disks (SSDs), silicon disk drives (SDDs), ROMs, RAMs, CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc., and also includes media implemented in the form of carrier waves (e.g., transmission via the Internet). In addition, the computer may include a control unit (100) of the satellite broadcast receiver (30). Therefore, the detailed description above should not be construed as limiting in all respects, but should be considered as illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are intended to be included in the scope of the present invention.

Claims

1. An interface unit for receiving a satellite broadcast signal corresponding to a channel selected from a switch for selecting a satellite broadcast signal received by a satellite antenna, and transmitting a command signal including channel selection information for channel selection to the switch; A tuning unit that demodulates and decodes a satellite broadcast signal received from the switch and detects whether the decoded data contains a preset bit string; and When transmission of command signals corresponding to each of multiple channels is requested according to a user request or the performance of a preset function, each command signal is transmitted to the switch in a preset order according to a preset delay time. A satellite broadcast receiver characterized in that it includes a control unit that controls the tuning unit to demodulate and decode a satellite broadcast signal received from the switch each time a command signal is transmitted based on the frequency of the channel corresponding to the transmitted command signal, determines whether fixation of the channel corresponding to the transmitted command signal is possible based on whether the decoded data includes a preset bit string, and changes the delay time based on whether channel fixation is possible.

2. In the first paragraph, the control unit, As a result of determining whether channel fixation is possible for the channel selected according to the above-mentioned preset order, if channel fixation is not possible, the delay time is increased by the preset time, A satellite broadcast receiver characterized in that when the increased delay time elapses, a command signal corresponding to the selected channel is retransmitted to the switch to determine whether the channel is fixed.

3. In the first paragraph, the tuning part, An oscillator that oscillates a local signal having a local frequency corresponding to the frequency of a channel selected according to the above-described preset order; A demodulator for demodulating a satellite broadcast signal whose frequency band has been changed according to a satellite broadcast signal mixed with the above local signal; A decoding unit that decodes the demodulated satellite broadcast signal according to a decoding method corresponding to a preset encoding method; and A satellite broadcast receiver characterized by including a channel tuning detection unit that detects the preset bit sequence from the data stream of the decoded satellite broadcast signal.

4. In the third paragraph, the control unit, By mixing the local signal with the satellite broadcast signal received from the switch, the received satellite broadcast signal is converted into a signal having a preset frequency band, A satellite broadcast receiver characterized in that when a selected channel is changed to another channel, the oscillation unit is controlled to oscillate a local signal having a local frequency corresponding to the frequency of the changed other channel, and the local signal having a local frequency corresponding to the frequency of the other channel is mixed with a satellite broadcast signal received from the switch.

5. In paragraph 1, The above control unit, When the demodulation of the above satellite broadcast signal is completed, errors that may occur in the demodulation process are corrected according to at least one of the preset error correction methods. The above preset error correction methods are: A satellite broadcast receiver characterized by including FEC (Forward Error Correction).

6. In the first paragraph, the control unit, A satellite broadcasting receiver characterized in that, when transmission of command signals corresponding to each of a plurality of channels is requested according to the above user request or the performance of a preset function, a preset minimum delay time is set to determine whether a channel is fixed according to the transmitted command signal, and the delay time is increased in stages from the minimum delay time according to the result of determining whether the channel is fixed.

7. In paragraph 6, the minimum delay time is: A satellite broadcast receiver characterized by a delay time greater than the command interval delay specified in the DiSEqC (Digital Satellite Equipment Control) international standard.

8. In the first paragraph, the command signal is A satellite broadcast receiver characterized in that it includes TP (transponder) information including information on a satellite transmitting a broadcast signal corresponding to the specific channel, a polarization direction of a satellite signal corresponding to the specific channel, and information on a frequency band corresponding to the specific channel as channel selection information for selecting a specific channel.

9. In paragraph 1, the control unit, A command signal of a channel selected according to the above-described preset order is transmitted to the switch, and if channel fixation for the selected channel is possible as a result of determining whether the channel is fixed, information on the selected channel is stored as channel information and information on the changed delay time is stored. A satellite broadcasting receiver characterized in that, whenever channel fixation is possible according to a transmitted command signal, the stored delay time is updated with information on the delay time between the command signal of the channel for which channel fixation is possible and the command signal transmitted previously.

10. In paragraph 9, the control unit, A satellite broadcasting receiver characterized in that, when a continuous channel switching request is received, a plurality of command signals corresponding to the continuous channel switching request are sequentially transmitted to a switch according to information on a previously stored delay time.

11. In paragraph 1, The above preset function is channel tuning. The above control unit, If the preset conditions are met, the above channel tuning is performed. The above-mentioned conditions are: A satellite broadcast receiver characterized in that when there is no previously stored channel information, when at least a part of a satellite broadcast program is updated, when at least one of the switch and the satellite antenna is changed, and when the channel is not fixed for a satellite broadcast reception signal according to a channel according to the previously stored channel information.

12. In paragraph 1, the satellite broadcast receiver, A satellite broadcast receiver comprising a TV system.

13. When transmission of command signals corresponding to multiple channels is requested, a step of checking whether a preset delay time has elapsed after the second command signal of the second channel selected before the first channel selected in a preset order is transmitted to a switch that selects a satellite broadcast signal received by the satellite antenna; When the delay time has elapsed, a step of transmitting a first command signal including channel selection information of the first channel to the switch; A step of determining whether channel fixation is possible for a satellite broadcast signal received from the switch according to the first command signal; A step of storing channel information of the first channel if channel fixation is possible as a result of determining whether the channel is fixed; and A control method for a satellite broadcast receiver, characterized in that the method comprises the steps of: changing the delay time if channel fixation is not possible as a result of determining whether the channel is fixed; checking whether the delay time has elapsed according to the changed delay time; transmitting the first command signal to the switch; and re-performing the step of determining whether channel fixation is possible.

14. In paragraph 13, The step of determining whether the above channel fixation is possible is as follows: A step of oscillating a local signal having a local frequency according to the frequency of the first channel; A step of mixing a satellite broadcast signal received from the switch with the local signal according to the first command signal; A step of modulating and decoding a satellite broadcast signal whose frequency band is converted by mixing with the above local signal; and, A control method for a satellite broadcast receiver, characterized in that it comprises a step of determining whether channel locking is possible based on whether a bit string corresponding to a preset channel tuning frame is included in a data stream according to the decoded satellite broadcast signal.

15. In paragraph 13, the delay time is, A control method for a satellite broadcasting receiver, characterized in that the delay time is set to a preset minimum delay time and is gradually increased in units of preset time whenever the delay time is changed.

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