JP2009188492A - Mobile digital broadcast receiving tuner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically set a receivable broadcast station. <P>SOLUTION: When the signal quality of a signal of a broadcast station which is being received with a tuner A becomes less than a predetermined value, an MPU 23 switches a reception frequency of an RF unit 15 of a tuner B to acquire an CNR as signal quality data being received from an OFDM demodulation unit 16, and searches receivable broadcast stations. A channel list of the searched broadcast stations is stored in a memory 20, and radio wave reception via the tuner A is executed in accordance with the channel list. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mobile digital broadcast receiving tuner for receiving digital television broadcasts.

  In Patent Document 1, first and second distributors that distribute reception signals of a plurality of antennas, and outputs of first and second distributors are selected and supplied to first and second receivers. It is described that by having the first and second switches, optimal diversity reception can be realized when the first and second receivers receive signals of different frequencies.

  In Patent Literature 2, in a mobile broadcast receiver having an N-sequence receiver that receives digital broadcast signals having different frequencies, the temporal positional relationship of the output signals of the N-sequence receiver is adjusted to the same position. It describes that one output signal with good signal quality is selected from N series output signals adjusted to the same position.

  By the way, the in-vehicle digital broadcast reception tuner changes the reception area when the car moves, so the user can search for a broadcast station that can be received in the destination area and reset the broadcast station in advance. It is necessary to create a list of broadcast stations that can be received in each region and automatically switch to a broadcast station that can receive signals in that region when the user designates the region.

However, the method in which a user searches for a receivable broadcast station is not only troublesome, but also has the disadvantage that the user cannot view digital television broadcasts during that time. Also, the method of preparing a list of broadcast stations in advance is troublesome because the user must designate a reception area.
JP-A-3-293822 JP 2006-67402 A

   An object of the present invention is to enable automatic setting of receivable broadcasting stations.

  The mobile digital broadcast receiving tuner of the present invention is a tuner that receives digital television broadcasts, a switch circuit that selects a reception signal of a first antenna and a second antenna, and a first circuit that is selected by the switch circuit. And a first wireless reception circuit to which one of the reception signals of the second antenna is input, and a second wireless to which the other of the reception signals of the first and second antennas selected by the switch circuit is input. A broadcasting station in which a receiving station and a second radio receiving circuit search for a broadcasting station having a received signal quality of a certain value or more, and a broadcasting station having a received signal quality of a certain value or more is received by the first radio receiving circuit. And a control circuit to be set as

  According to the present invention, while the digital radio broadcast signal is received by the first radio reception circuit, the second radio reception circuit searches for a broadcast station having a received signal quality of a certain value or more, and the searched broadcast station is It can be set as a broadcasting station that receives a single radio receiving circuit. As a result, broadcast stations that can be received in the destination area can be automatically set.

  In the mobile digital broadcast reception tuner of the above invention, the second radio reception circuit includes a radio reception unit that receives a broadcast signal of a selected broadcast station and an OFDM demodulation unit that demodulates an OFDM signal.

With this configuration, it is possible to search for a broadcast station that can be received by the radio reception unit and the OFDM demodulation unit, so that the circuit configuration of the second radio reception circuit can be simplified.
In the mobile digital broadcast reception tuner of the above invention, the second radio reception circuit includes a radio reception unit that receives a broadcast signal of a selected broadcast station, an RSSI circuit that detects received signal strength, and the RSSI circuit. The A / D converter converts the output signal into a digital value.

  With this configuration, the configuration of the second radio reception circuit can be simplified.

  According to the present invention, it is possible to automatically set a broadcast station that can be received in a moved area.

  Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 is a circuit diagram of a mobile digital broadcast receiving tuner 11 according to the first embodiment. The mobile digital broadcast receiving tuner 11 is, for example, a vehicle-mounted tuner, and performs diversity reception by switching two antennas.

  In FIG. 1, digital television broadcast signals received by two antennas 1 and 2 (not shown) are input to two antenna terminals. The RF switch 12 includes two switches SW1 and SW2. By switching the switches SW1 and SW2, one of the signals of the antenna 1 and the antenna 2 is output to the RF unit 13, and the other signal is output to the RF unit 15. .

The RF units 13 and 15 select the frequency of the received signal of the antenna 1 and the antenna 2 selected by the RF switch 12 to extract a desired wave signal.
OFDM (Orthogonal Frequency Division Multiplexing) demodulation units 14 and 16 perform demodulation and error correction processing on the OFDM signal and output TS (Transport Stream) packets to the media processor 17 and the MPU 23. The RF unit 13 and the OFDM demodulation unit 14 constitute a tuner A (corresponding to the first radio reception circuit), and the RF unit 15 and the OFDM demodulation unit 16 constitute a tuner B (corresponding to the second radio reception circuit). To do.

  The media processor 17 is an H.264 medium. The TS packet compressed by H.264 and AAC (Advanced Audio Coding) is separated into video data, audio data, and additional data, and output to the video encoder 18, D / A converter 19, and memory 20, respectively.

  The video encoder 18 decodes the video data and outputs an analog video signal to the video output terminal 21. The D / A converter 19 D / A converts the audio data and outputs an analog audio signal to the audio output terminal 22.

  The MPU 23 obtains data (in this case, CNR (Carrier to Noise Ratio)) indicating the received signal quality of the broadcast signal received by the tuner A from the media processor 17, and when the CNR is less than a certain value, The reception frequency of B is sequentially switched to search for a broadcasting station having a CNR of a certain value or more. Then, the searched broadcast station name is set in the memory 20. As a result, even if the reception area changes and the CNR decreases while traveling by car, it is possible to automatically search for receivable broadcast stations and preset those broadcast stations as receivable broadcast stations.

Next, the operation of the mobile digital broadcast receiving tuner 11 configured as described above will be described with reference to the flowcharts of FIGS.
When the power is turned on (FIG. 2A, S11), the MPU 23 sets the RF switch 12 so that the signal of the antenna ANT1 is output to the tuner A. Then, the sensitivity data of the broadcast signal being received is acquired from the media processor 17, and it is determined whether the reception sensitivity is good (is greater than a certain value) or bad (is less than a certain value) (S13).

When the reception sensitivity of the antenna ANT1 is good (S13, good), reception continues with the antenna ANT1.
When the reception sensitivity of the antenna ANT1 is poor (S13, bad), the process proceeds to step 14, the RF switch 12 is switched, and the reception signal of the antenna ANT2 is input to the tuner A. Then, it is determined whether the reception sensitivity of the antenna ANT2 is good or bad (S15). When the reception sensitivity of the antenna ANT2 is good (S15, good), the reception is continued as it is.
When the reception sensitivity of the antenna ANT2 is poor (S15, bad), the process returns to step S12 and the above-described processing is repeated.

Next, an operation for automatically setting a receivable broadcasting station will be described with reference to FIG.
During diversity reception using two antennas ANT1 and ANT2 (FIG. 2 (B), S21), data CNR indicating the signal quality of the broadcast signal being received by tuner A is acquired from media processor 17. Then, it is determined whether the signal being received by the tuner A is good (is greater than a certain value) or bad (is less than a certain value) (S22).

  If the CNR of the signal being received is good (S22, good), the reception is continued as it is. If the CNR of the signal being received is bad (S22, bad), the process proceeds to step 23, and the area setting information (current position information) set in the media processor 17 is read.

  In order to preset a broadcast station that can be received by the mobile digital broadcast reception tuner 11, the user performs an operation for setting a reception area in advance, and the area designation information set by this operation is, for example, the media processor 17. It is stored in a flash memory (not shown). Further, since the memory 20 stores the frequencies of broadcast stations that can be received in each area of the country as a channel list, if the current position is known by the area designation information, the frequencies of broadcast stations that can be received in the surrounding area. Can be obtained from the memory 20.

In order to search for a channel, a channel list of broadcasting stations in the surrounding area of the current position is acquired (S24).
Next, the frequency of the broadcast station acquired in tuner B is set (S25). In the process of step S25, the broadcast station may be searched by sequentially switching frequencies. Then, it is determined whether the CNR of the signal received by the tuner B is good (is greater than a certain value) or bad (S26). If the CNR is bad, the process returns to step 24, the frequency of the next broadcasting station is acquired, and the above processing is repeated.

When the CNR of the signal received by tuner B is equal to or greater than a certain value (S26, good), the process proceeds to step 27, and the broadcasting station is registered in the channel list of tuner A.
The above processing is also performed for other broadcasting stations, and broadcasting stations having a CNR of a certain value or more are registered in the channel list. Through these processes, a channel list of broadcast stations that can be received at the current position is automatically created, and a broadcast station to be received by tuner A is determined according to the channel list.

  According to the first embodiment described above, even if the received signal quality of a receiving broadcast station is reduced due to movement, a broadcast station that can be received at the current position by another tuner B can be searched and received. It is possible to automatically create a channel list of various broadcasting stations. Thereby, even when the reception area changes by moving by a car or the like, it is possible to set a broadcast station that can always receive in the tuner A.

  Further, the tuner B for searching for a receivable broadcast station can be composed of two circuits, that is, the RF unit 15 and the OFDM demodulator 16, so that the circuit configuration for searching for a broadcast station is simplified. The cost is also cheaper.

  In addition, when the broadcast station information indicating the series of broadcast stations in each region is stored in advance in the memory or the broadcast station information is acquired from the broadcast signal, and the received signal quality of the currently receiving broadcast station is reduced, It is also possible to automatically switch to another broadcasting station that can receive the same series as the receiving broadcasting station. As a result, the TV program being viewed can be viewed continuously.

Next, FIG. 3 is a circuit diagram of the mobile digital broadcast receiving tuner 31 of the second embodiment. In the following, the same circuit blocks as those of the circuit of FIG.
The RSSI circuit 32 detects the received signal strength of the received signal output from the RF unit 15 and outputs the detected RSSI signal to the A / D converter 33. The A / D converter 33 converts the RSSI signal into digital data and outputs the digital data to the MPU 23.

  The MPU 23 determines whether or not the broadcast station received by the RF unit 15 is receivable based on whether or not the digital data (the digital value of the RSSI signal) output from the A / D converter 33 is greater than or equal to the reference value. If reception is possible, the broadcast station is registered in the channel list of the memory 20. The MPU 23 instructs the RF unit 15 to receive the next broadcast station and performs the same operation as described above.

  As a result, a channel list indicating a plurality of broadcast stations that can be received at the current position is automatically created and stored in the memory 20. Therefore, the MPU 23 can determine a broadcast station to be received by the main tuner (consisting of the RF unit 13 and the OFDM demodulation unit 14) according to the channel list.

  According to the second embodiment described above, even if the reception level of the receiving broadcast station is reduced due to movement, a broadcast station that can be received at the current position by the tuner from the RF unit 15 and the RSSI circuit 32 or the like. And the searched broadcast station can be automatically set in the main tuner (consisting of the RF unit 13 and the OFDM unit 14). Thus, a receivable broadcast station can be automatically set without the user manually setting a broadcast station in the destination area.

  Furthermore, a tuner for searching for a broadcasting station can be configured by the RF unit 15, the RSSI circuit 32, and the A / D converter 33, so that the circuit configuration is simple and the cost is reduced.

1 is a circuit diagram of a mobile digital broadcast reception tuner of a first embodiment. FIG. It is a flowchart which shows operation | movement of the mobile digital broadcast receiving tuner of 1st Embodiment. It is a circuit diagram of the mobile digital broadcast receiving tuner of the second embodiment.

Explanation of symbols

11, 31 Mobile digital broadcast receiving tuner 12 RF switch 13, 15 RF unit 14, 16 OFDM demodulator 17 Media processor 20 Memory 23 MPU
32 RSSI circuit 33 A / D converter

Claims (4)

A mobile digital broadcast receiving tuner for receiving digital television broadcasts,
A switch circuit for selecting reception signals of the first antenna and the second antenna;
A first wireless reception circuit to which one of the reception signals of the first and second antennas selected by the switch circuit is input;
A second wireless reception circuit to which the other of the reception signals of the first and second antennas selected by the switch circuit is input;
Control for searching for a broadcasting station having a reception signal quality of a certain value or more by the second wireless reception circuit, and setting a broadcasting station having a reception signal quality of a certain value or more as a broadcasting station to be received by the first wireless reception circuit A mobile digital broadcast receiving tuner comprising a circuit.   2. The mobile digital broadcast receiving tuner according to claim 1, wherein the second wireless reception circuit includes a wireless reception unit that receives a broadcast signal of a selected broadcast station and an OFDM demodulation unit that demodulates an OFDM signal.   The second radio reception circuit includes a radio reception unit that receives a broadcast signal of a selected broadcast station, an RSSI circuit that detects received signal strength, and an A / D that converts an output signal of the RSSI circuit into a digital value. 2. The mobile digital broadcast receiving tuner according to claim 1, comprising a converter.   When the control circuit detects that the reception area has changed due to movement and the received signal quality of the broadcasting station being received by the first wireless reception circuit is less than a certain value, the second wireless reception circuit The mobile digital broadcast receiving tuner according to claim 1, 2 or 3, wherein a search is made for a broadcasting station having a reception signal quality of a certain value or more.

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