KR100744783B1 - Method for searching channels automatically - Google Patents

Abstract

The present invention relates to a method for automatic search of a digital broadcast channel, in particular, in digital broadcasting. In order to speed up the search of a broadcast channel through a representative frequency search, a plurality of broadcast frequencies are divided into a plurality of groups according to a broadcast channel. One of the broadcast frequencies belonging to each group is set as the representative frequency, and the other broadcast frequencies belonging to the representative frequency group in which the broadcast signal is tuned in the search results while searching for the broadcast channels for the representative frequencies of the plurality of groups. The present invention relates to a method for automatically searching a channel for performing a broadcast channel search.

Broadcast Channel, Channel Search, Broadcast Frequency

Description

Method for searching channels automatically}

1 is a diagram illustrating a terminal configuration for automatic search of a channel according to the present invention.

2A-2C illustrate an automatic search procedure for a channel in accordance with the present invention.

The present invention relates to digital broadcasting, and more particularly, to a method for automatic search of a digital broadcasting channel.

In general, a communication terminal providing a digital broadcast service includes a frequency table including broadcast frequencies for broadcast channels.

Therefore, when the user requests watching a specific broadcast program, the communication terminal searches all broadcast frequencies in the frequency table to find a broadcast frequency corresponding to the broadcast channel of the requested broadcast program.

If 100 broadcast frequencies are included in the frequency table, all 100 searches are performed to find the broadcast frequencies of broadcast programs requested by the user.

If only 3 out of 100 broadcast frequencies are broadcast frequencies of a valid broadcast channel, conventionally, up to 97 broadcast frequencies that are unnecessary are searched. Therefore, there is a problem that the entire time taken to search for a broadcast channel becomes long.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for automatically searching a channel for faster searching of a broadcast channel through a representative frequency search.

A feature of the automatic channel search method according to the present invention for achieving the above object comprises: dividing a plurality of broadcast frequencies into a plurality of groups according to a broadcast channel; Determining one of broadcast frequencies belonging to each group as a representative frequency; Conducting a search of a broadcast channel for the representative frequencies of the plurality of groups; And checking whether the broadcast signal is tuned in the remaining broadcast frequencies of the group to which the representative frequency to which the broadcast signal is effectively tuned in the search.

Preferably, the weight is increased or decreased to broadcast frequencies belonging to the group according to whether the broadcast signal is successfully tuned. Here, the weight is increased for the broadcast frequency that succeeds in tuning the broadcast signal.

Preferably, the method further includes storing broadcast frequencies to which the broadcast signal is effectively tuned as broadcast frequencies of the valid broadcast channel.

Preferably, a weight is checked for the remaining broadcast frequencies of the group to which the representative frequency to which the broadcast signal is not effectively tuned in the search is checked to determine whether the broadcast signal is successfully tuned to the broadcast frequencies having a weight greater than or equal to the level. .

Another feature of the automatic channel search method according to the present invention for achieving the above object comprises the steps of: dividing a plurality of broadcast frequencies into a plurality of groups; Determining one of broadcast frequencies belonging to each group as a representative frequency; And confirming whether or not the broadcast signal with respect to the representative frequency of each of the predetermined groups is successfully tuned.

The method may further include determining whether the broadcast signal is tuned at the remaining broadcast frequencies of the group to which the representative frequency succeeded in tuning the broadcast signal belongs.

Preferably, a weight is checked for the remaining broadcast frequencies of the group to which the representative frequency that fails to tune the broadcast signal belongs to determine whether the broadcast signal is successfully tuned to the broadcast frequencies having a weight greater than or equal to a predetermined level.

Another feature of the automatic channel search method according to the present invention for achieving the above object comprises the steps of: dividing a plurality of broadcast frequencies into a plurality of groups per broadcast channel; Determining a search priority of broadcast frequencies belonging to each group; And performing a primary broadcast channel search for broadcast frequencies given the highest priority in the plurality of groups.

Preferably, if there is a broadcast frequency in which the broadcast signal is effectively tuned in the primary broadcast channel search, the broadcast channel is further searched for the remaining broadcast frequencies of the group to which the corresponding broadcast frequency to which the broadcast signal is effectively tuned belongs. do. Here, the broadcast frequency to which the broadcast signal is effectively tuned is stored as a broadcast frequency of a valid broadcast channel. In addition, the weight given to the broadcast frequency to which the broadcast signal is effectively tuned is increased.

Preferably, if there is no broadcast frequency to which a broadcast signal is effectively tuned in the primary broadcast channel search, a broadcast channel search is further performed for broadcast frequencies to which the second priority of the plurality of groups is given.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described by at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

In the present invention, the structure shown in Table 1 below is used to search for a plurality of broadcast frequencies included in the frequency table more quickly when the broadcast channel is automatically searched. Hereinafter, as shown in Table 1, it is assumed that the total broadcast frequencies included in the frequency table are 21.

Group No. Priority Broadcast frequency of frequency table weight  One One 133 3 2 132 0 3 131 0  2 One 123 0 2 122 2 3 121 0  3 One 113 0 2 112 0 3 111 0  4 One 103 0 2 102 0 3 101 0  5 One 93 0 2 92 0 3 91 0  6 One 83 0 2 82 0 3 81 0  7 One 73 0 2 72 0 3 71 0

In the present invention, a plurality of broadcast frequencies included in a frequency table are divided into a plurality of groups, and broadcast frequencies belonging to each group are given priority to be applied at the time of searching. Each group corresponds to a broadcast channel, and three different broadcast frequencies may be allocated to each broadcast channel. Broadcast channels may be classified by broadcasters.
Table 1 is divided into seven groups, which indicates that seven broadcast channels are used. If all seven broadcast channels from broadcast channel 1 to broadcast channel 7 correspond to the frequency band 174 to 216 MHz, each broadcast channel is allocated by a frequency band of 6 MHz. Each broadcast channel is divided into three different broadcast frequencies. Therefore, each broadcast frequency corresponds to a frequency band of 2MHz.
For example, if broadcaster A has acquired the right to use broadcast channel 1 corresponding to the first group, the broadcaster A may provide three different broadcasts through broadcast channel 1.
In the present invention, the broadcasting frequency searched for the highest priority in each group is defined as the representative frequency of the group.
Meanwhile, the present invention is to automatically search for a broadcast channel in a terminal supporting a digital broadcast service.

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Preferably, the terminal is a communication terminal that supports a digital broadcasting service, and more preferably, a communication terminal that receives and outputs a terrestrial broadcast signal.

1 is a diagram illustrating a terminal configuration for automatic search of a channel according to the present invention.

Referring to FIG. 1, the communication terminal according to the present invention includes a frequency table 10, a control unit 20, and a storage unit 30.

The frequency table 10 includes a plurality of broadcast frequencies. The frequency table 10 is more preferably included in the storage unit 30. However, in order to clarify the features of the present invention it is described as a separate component in FIG.

The storage unit 30 stores the broadcast frequency of the valid broadcast channel searched by the control unit 20.

The controller 20 divides the broadcast frequencies included in the frequency table 10 into a plurality of groups.

The control unit 20 gives priority to each group of broadcasting frequencies in the search. At this time, the broadcasting frequency of the highest priority for each group is determined as the representative frequency of the corresponding group. As another example, priority may not be given to broadcasting frequencies belonging to each group during the initial operation (first operation after production), and thus, the representative frequency for each group may not be determined during the initial operation. . In the initial operation, the controller 20 first searches for all broadcast frequencies included in the frequency table to find a valid broadcast frequency, and then performs a selective search described below after the initial search.

That is, the controller 20 searches in the divided group unit when searching the broadcast frequencies included in the frequency table 10, but searches in each group according to the given priority.

More specifically, the control unit 20 gives priority to each group of broadcast frequencies belonging to the group at the time of searching, and sets the highest priority broadcast frequency in each group as the representative frequency of the group. At this time, the broadcast frequency in which the broadcast signal is effectively tuned in the aforementioned first search is determined as the representative frequency of the corresponding group.

Thereafter, the controller 20 performs a primary search in group units. That is, the broadcast frequency to which the broadcast signal is tuned is found among the representative frequencies of the groups. The group unit search may be performed sequentially or randomly.

If a broadcast signal is effectively tuned at a representative frequency of a specific group, a second search is performed for other broadcast frequencies belonging to the group.

The controller 20 stores the broadcast frequencies of the valid broadcast channels searched for in the primary and secondary in the storage unit 30.

For example, referring to Table 1 and FIG. 1, the controller 20 divides 21 broadcasting frequencies from "133" to "71" into seven groups. One group corresponds to one broadcast channel, and a right to use the broadcast channel is given to one broadcaster. Each broadcast channel includes three different broadcast frequencies used to provide different broadcasts. As an example, the frequency group 13 includes broadcast frequencies of "133, 132, 131". The frequency group 12 includes broadcast frequencies of "123, 122, 121".

The controller 20 determines the representative frequencies of each group by giving priority to be applied to the broadcast frequencies of the seven groups in the search. When the representative frequencies of the seven groups are sequentially arranged, they are "133,123,113,103,93,83,73". As described above, in the present invention, a representative frequency of each group may be arbitrarily determined, and a broadcast frequency in which a broadcast signal is effectively tuned among broadcast frequencies belonging to a specific group in the aforementioned initial search is defined as the representative frequency of the group.

In the present invention, the predetermined representative frequency is not fixedly applied but is changed every time the search is performed through the above-described first and second search. That is, the controller 20 changes the representative frequency of each group at each search.
As an example, the representative frequencies of seven groups are determined according to the priority given to the broadcast frequencies, and the broadcast frequencies given the highest priority in the seven groups, that is, the representative frequencies are "133,123,113,103,93,83,73". This is called. The channel is automatically searched for the predetermined representative frequencies. Subsequently, in the next automatic search of the channel, the control unit 20 performs the automatic search of the channel after changing the second priority "132, 122, 112, 102, 92, 82, 72" from the seven groups to the representative frequencies. . When the next channel is automatically searched, "131, 121, 111, 101, 91, 81, 71", which is assigned the third priority in the seven groups, is set as the representative frequencies and the channel is automatically searched.
As another example, the representative frequencies of seven groups are determined according to the priority given arbitrarily to the broadcast frequencies, and the broadcast frequencies given the highest priority in seven groups, that is, the representative frequencies are "133,123,113,103,93,83,73". Is called. The control unit 20 performs an automatic search for the predetermined representative frequencies once. Based on this automatic search result, weights are applied to each representative frequency, and the representative frequencies of the groups are changed according to the applied weights. An example of the above-mentioned weight application is described next.

On the other hand, as a further example, the control unit 20 automatically performs a search for the representative frequencies listed above, and checks whether there is a broadcast frequency in which the broadcast signal is effectively tuned among the representative frequencies. If there is a broadcast frequency to which the broadcast signal is effectively tuned, channel automatic search is performed for all remaining broadcast frequencies of the group to which the broadcast frequency belongs.

For example, if the broadcast signal is not tuned in "133,123" and the broadcast signal is effectively tuned in "113" of the next group No. 3, as shown in Fig. 1, the control unit 20 fails to tune to the broadcast frequency. No additional search is performed for groups belonging to "133,123", but an additional search is performed for group No. 3 to which broadcast station "113" succeeded in tuning. The control unit 20 further performs a search according to the priority given to the remaining broadcast frequencies "112, 111" belonging to the group No. 3. In detail, after searching whether the broadcast signal is effectively tuned at "112" of the second priority among the remaining broadcast frequencies ("112,111") belonging to the group No. 3, the broadcast signal at the "111" of the third priority Search for whether is effectively tuned in.

When the intra-group search in the group No. 3 is completed, the control unit 20 then performs the search for the remaining representative frequencies "103, 93, 83, 73".

On the other hand, the controller 20 increases the weight for the broadcast frequency of the effective broadcast channel to which the broadcast signal is tuned, and decreases the weight for the broadcast frequency for which the broadcast signal is not tuned in the search process. The above-mentioned weight is a value applied to each broadcasting frequency to refer to the next channel search, and preferably has a maximum value of 3.

In particular, the weight according to the present invention is a value applied every time the channel is searched, and is given to indicate the number of successful searches for the broadcast frequency. Therefore, each time the broadcast signal is tuned at the broadcast frequency, the weight set for the broadcast frequency is increased by one. The maximum value of the weight is three.

An automatic search procedure of the channel in the controller 20 and an example of applying a weight in the automatic search procedure will be described in more detail with reference to FIGS. 2A to 2C.

2A to 2C are diagrams illustrating an automatic search procedure of a channel according to the present invention. First, the automatic search procedure of a channel according to the present invention will be described. 2A to 2C, an example of automatic search for a channel when a broadcast frequency is divided into three groups will be described.

The communication terminal stores a plurality of broadcast frequencies as shown in Table 1 above, and specifically divides the plurality of broadcast frequencies into a plurality of groups for each broadcast channel. The broadcast frequencies belonging to the above groups are prioritized when searching.

If the automatic search for the broadcast channel is initiated by the user's request, the communication terminal performs the search in units of the divided groups. However, when a user requests an automatic search for a broadcast channel in a general manner, the communication terminal searches for broadcast frequencies included in the frequency table one by one.

Meanwhile, as the automatic search for the broadcast channel starts, the communication terminal checks whether the broadcast signal is effectively tuned to the representative frequencies of the groups. That is, confirm that channel tuning for the representative frequencies is successful. At this time, the representative frequency to which the broadcast signal is tuned is stored as a broadcast frequency of a valid broadcast channel. The weight is increased by 1 for the stored representative frequency.

Subsequently, in-group searching is further performed in the group of representative frequencies to which the broadcast signal is tuned. That is, the communication terminal further checks whether the broadcast signal is effectively tuned to the remaining broadcast frequencies in the group in the representative frequency group in which the broadcast signal is effectively tuned. At this time, the group is searched in order according to the priority given to the remaining broadcast frequencies. If there is a broadcast frequency in which a broadcast signal is effectively tuned among the remaining broadcast frequencies, the broadcast frequency is stored as a frequency of a valid broadcast channel and the weight is increased by 1 for the stored broadcast frequency.

When the search in the one group is completed, it is checked whether the broadcast signal for the next representative frequency is tuned.

2A to 2C, the controller of the communication terminal divides a plurality of broadcast frequencies included in a frequency table into first to third groups. It is assumed that one group includes three different broadcasting frequencies used by different broadcasting stations for the broadcasting channel.

The control unit assigns priorities to be applied at the time of searching to the broadcast frequencies of the three groups to determine the representative frequencies of each group.

When the automatic search of the channel is started, the controller searches the representative frequency of the first group and checks whether a broadcast signal is tuned at the representative frequency of the first group (S10-12).

When the broadcast signal is tuned at the representative frequency of the first group, the control unit stores the representative frequency of the first group as a frequency of a valid broadcast channel (S13). At this time, the weight is increased by 1 for the representative frequency of the first group to be stored. However, if the broadcast signal is not tuned in the representative frequency of the first group, the control unit searches for the representative frequency of the next second group without performing any search for the broadcast frequency of the first group (S20). At this time, the weight is reduced by 1 for the representative frequency of the first group in which the broadcast signal is not tuned.

Meanwhile, as the broadcast signal is tuned at the representative frequency of the first group, the control unit searches for the remaining broadcast frequencies of the next priority belonging to the first group. The control unit searches for the broadcast frequency of the second priority belonging to the first group (S14).

If a broadcast signal is tuned at the broadcast frequency of the second priority of the first group, the controller stores the broadcast frequency of the second priority as a frequency of a valid broadcast channel (S15-16). At this time, the weight is increased by 1 for the broadcasting frequency of the second priority stored. However, if the broadcast signal is not tuned at the broadcast frequency of the second priority, the control unit searches for the broadcast frequency of the third priority belonging to the first group (S17), and the broadcast frequency of the second priority where the broadcast signal is not tuned. For, decrease the weight by 1.

If a broadcast signal is tuned at the broadcast frequency of the third priority of the first group, the controller stores the broadcast frequency of the third priority as a frequency of a valid broadcast channel (S18 to 19). At this time, the weight is increased by 1 with respect to the stored broadcast frequency of the third priority and the search for the first group is completed.

On the other hand, if the broadcast signal is not tuned in the broadcast frequency of the third priority, the control unit completes the search for the first group, and decreases the weight by 1 for the broadcast frequency of the third priority that is not tuned.

When the channel search for the first group is completed, the control unit searches for the representative frequency of the second group and checks whether a broadcast signal is tuned at the representative frequency of the second group (S20 to 21).

When the broadcast signal is tuned at the representative frequency of the second group, the control unit stores the representative frequency of the second group as a frequency of a valid broadcast channel (S22). At this time, the weight is increased by 1 for the representative frequency of the second group to be stored. However, if the broadcast signal is not tuned in the representative frequency of the second group, the control unit searches for the representative frequency of the next third group without performing any search for the broadcast frequency of the second group (S29). At this time, the weight is reduced by 1 for the representative frequency of the second group in which the broadcast signal is not tuned.

Meanwhile, as the broadcast signal is tuned at the representative frequency of the second group, the control unit searches for the remaining broadcast frequencies of the next priority belonging to the second group. The control unit searches for a broadcast frequency of the second priority belonging to the second group (S23).

If a broadcast signal is tuned at the broadcast frequency of the second priority of the second group, the controller stores the broadcast frequency of the second priority as a frequency of a valid broadcast channel (S24-25). At this time, the weight is increased by 1 for the broadcasting frequency of the second priority stored. However, if the broadcast signal is not tuned at the broadcast frequency of the second priority, the control unit searches for the broadcast frequency of the third priority belonging to the second group (S26), and the broadcast frequency of the second priority where the broadcast signal is not tuned. For, decrease the weight by 1.

If a broadcast signal is tuned at the broadcast frequency of the third priority of the second group, the control unit stores the broadcast frequency of the third priority as a frequency of a valid broadcast channel (S27 to 28). At this time, the weight is increased by 1 for the stored broadcast frequency of the third priority and the search for the second group is completed.

On the other hand, if the broadcast signal is not tuned in the broadcast frequency of the third priority, the control unit completes the search for the second group, and decreases the weight by 1 for the broadcast frequency of the third priority that is not tuned.

When the channel search for the second group is completed, the controller searches the representative frequency of the third group and checks whether a broadcast signal is tuned at the representative frequency of the third group (S29-30).

When the broadcast signal is tuned at the representative frequency of the third group, the control unit stores the representative frequency of the third group as a frequency of a valid broadcast channel (S31). At this time, the weight is increased by 1 for the representative frequency of the third group to be stored. However, if the broadcast signal is not tuned at the representative frequency of the third group, the controller terminates the procedure of the automatic search for the channel without performing any search for the broadcast frequency of the third group. At this time, the weight is reduced by 1 for the representative frequency of the third group in which the broadcast signal is not tuned.

Meanwhile, as the broadcast signal is tuned at the representative frequency of the third group, the control unit searches for the remaining broadcast frequencies of the next priority belonging to the third group. The control unit searches for the broadcast frequency of the second priority belonging to the third group (S32).

If a broadcast signal is tuned at the broadcast frequency of the second priority of the third group, the control unit stores the broadcast frequency of the second priority as a frequency of a valid broadcast channel (S33 to 34). At this time, the weight is increased by 1 for the broadcasting frequency of the second priority stored. However, if the broadcast signal is not tuned at the broadcast frequency of the second priority, the control unit searches for the broadcast frequency of the third priority belonging to the third group (S35), and the broadcast frequency of the second priority where the broadcast signal is not tuned. For, decrease the weight by 1.

If a broadcast signal is tuned at the broadcast frequency of the third priority of the third group, the control unit stores the broadcast frequency of the third priority as a frequency of a valid broadcast channel (S36 to 37). At this time, the weight is increased by 1 with respect to the stored broadcast frequency of the third priority and the search for the third group is completed.

On the other hand, if the broadcast signal is not tuned in the broadcast frequency of the third priority, the control unit completes the search for the third group, and decreases the weight by 1 for the broadcast frequency of the third priority that is not tuned.

In addition to completing the search for the third group, the controller terminates all automatic search procedures for the channel.

In the present invention, the weights described above are used as follows in the channel search process.

If a broadcast signal is tuned at a specific broadcast frequency during channel search, the controller increases the weight set for the broadcast frequency by one.

If a broadcast signal is not tuned at a specific broadcast frequency during channel search, the controller decreases the weight set for the broadcast frequency by one.

On the other hand, if the broadcast signal is not tuned to the representative frequency of the N-th group, the controller described above does not perform any search for the broadcast frequencies belonging to the N-th group while reducing the weight of the representative frequency by one.

As another example, in the present invention, when the broadcast signal is not tuned at the representative frequency of the N-th group, the controller checks the weights of the remaining broadcast frequencies belonging to the N-th group. Subsequently, the controller searches for the remaining broadcast frequencies of the N-th group having a weight equal to or greater than a predetermined value (eg, weight 1). For example, even if a broadcast signal is not tuned at the representative frequency of the N-th group, if there is a broadcast frequency having a weight of 1 or more among the remaining broadcast frequencies belonging to the N-th group, the control unit determines that the broadcast signal is generated at the broadcast frequency having the weight of 1 or more. Check that the station is tuned.

However, in the present invention, whether or not the broadcast signal is tuned to the representative frequencies regardless of the weight.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

According to the present invention, since the broadcast frequency included in the frequency table is divided into a plurality of groups having a representative frequency and the channel is automatically searched by the group, the search of the broadcast channel is very fast even when using a large number of broadcast frequencies. .

In addition, the efficiency of channel search is improved by using a weight indicating the number of successful searches for a broadcast frequency every time the channel is searched.

Claims (13)

Dividing a plurality of broadcast frequencies into a plurality of groups according to a broadcast channel; Determining one of broadcast frequencies belonging to each group as a representative frequency; Conducting a search of a broadcast channel for the representative frequencies of the plurality of groups; And And checking whether the broadcast signal is tuned at the remaining broadcast frequencies of the group to which the representative frequency to which the broadcast signal is effectively tuned in the search is performed. Claim 2 was abandoned when the setup registration fee was paid. The method of claim 1, wherein a weight is increased or decreased for broadcast frequencies belonging to the group according to whether the broadcast signal is successfully tuned. The method of claim 1, further comprising storing broadcast frequencies to which the broadcast signal is effectively tuned as broadcast frequencies of valid broadcast channels. Claim 4 was abandoned when the registration fee was paid. 3. The method of claim 2, wherein the weight is increased for a broadcast frequency that is successful in tuning the broadcast signal. 2. The method of claim 1, wherein the broadcast signal is successfully tuned to the broadcast frequencies having a weight greater than or equal to the remaining broadcast frequencies of the group to which the representative frequency to which the broadcast signal is not effectively tuned in the search. The automatic search method of the channel, characterized in that for checking. Dividing a plurality of broadcast frequencies into a plurality of groups; Determining one of broadcast frequencies belonging to each group as a representative frequency; And And checking whether or not the channel signal has been successfully tuned to the representative frequency of each of the predetermined groups. 7. The method of claim 6, further comprising: checking whether the broadcast signal is tuned at the remaining broadcast frequencies of the group to which the representative frequency successfully selected for the broadcast signal belongs. 7. The method of claim 6, wherein a weight is checked for the remaining broadcast frequencies of the group to which the representative frequency failed to tune the broadcast signal belongs to determine whether the broadcast signal is successfully tuned to the broadcast frequencies having a weight greater than or equal to a predetermined level. Automatic channel search method. Dividing a plurality of broadcast frequencies into a plurality of groups for each broadcast channel; Determining a search priority of broadcast frequencies belonging to each group; And And performing a primary broadcast channel search for the broadcast frequencies to which the highest priority is assigned in the plurality of groups. 10. The method of claim 9, wherein if there is a broadcast frequency in which the broadcast signal is effectively tuned in the primary broadcast channel search, the search of the broadcast channel is performed for the remaining broadcast frequencies of the group to which the corresponding broadcast frequency in which the broadcast signal is effectively tuned belongs. The automatic search method of the channel, characterized in that further performing. The method of claim 10, wherein the broadcast frequency to which the broadcast signal is effectively tuned is stored as a broadcast frequency of a valid broadcast channel. Claim 12 was abandoned upon payment of a registration fee. 12. The method of claim 10, wherein a weight assigned to a broadcast frequency to which the broadcast signal is effectively tuned is increased. 10. The method of claim 9, wherein if there is no broadcast frequency to which a broadcast signal is effectively tuned in the primary broadcast channel search, a broadcast channel search is further performed for broadcast frequencies to which the second priority of the plurality of groups is given. Automatic channel search method.

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