JP2012104863A - Digital broadcast receiver and receiving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital broadcast receiver which can minimize power consumption of a plurality of tuners while maintaining the diversity reception function.SOLUTION: The digital broadcast receiver comprises N built-in antennas 100(1)-100(N), N tuners 130(1)-130(N), N power source switches 160(1)-160(N), a carrier synthesis unit 201 which synthesizes a plurality of individual carrier signals, and a demodulation unit 202 which demodulates video and audio signals from carrier signals. A CPU 205 controls N power source switches 160(1)-160(N) so as to select a tuner to be used based on the detection results from individual carrier C/N detection units 150(1)-150(N) and a synthetic carrier C/N detection unit 204, to supply power to the tuner thus selected, and to stop power supply to the tuners not selected.

Description

  The present invention relates to a portable digital broadcast receiving apparatus and a digital broadcast receiving method capable of performing stable broadcast signal reception by a diversity reception function using a plurality of antennas.

  Portable portable television broadcast receivers have been widely used in the past, but in order to receive broadcast radio waves with a rod antenna attached to the receiver, compared to when receiving with a fixed antenna installed outdoors, It is difficult to obtain sufficient received signal strength. For this reason, the playback screen is also noisy or easily becomes a so-called ghost screen due to the influence of reflected waves, and there is a problem in playback video quality. However, in recent years, the problem has been solved by digitalization of broadcasting.

  In terrestrial digital broadcasting, a modulation method called OFDM (Orthogonal Frequency Division Multiplex) is used, but this modulation method is resistant to multiple reflection propagation (so-called multipath) environments, and can suppress the transmission error rate to a low level. There are features.

  There is also a technique called diversity reception that can improve the reception strength of radio waves. Diversity reception is to receive broadcast radio waves with multiple antennas with different reception conditions and select the antenna with the best reception state from them, or combine the received radio waves with multiple antennas. This is a technique for improving reception quality as compared with the case of reception. By using this diversity reception and OFDM in combination, the reception quality can be improved more effectively. That is, it is known that reception quality can be greatly improved by optimally combining a plurality of radio waves having different reception levels and delay characteristics, instead of simply selecting an antenna having the maximum reception power by diversity reception. ing. In practice, diversity reception is practically used in a vehicle-mounted digital broadcast receiving apparatus that is assumed to have a very poor reception environment.

As described above, diversity reception is very effective in receiving digital broadcasts using OFDM modulation, and many improvements have been proposed to enhance the effect. For example, Patent Document 1 proposes a configuration that further enhances the synthesis effect by individually adjusting the characteristics of each tuner installed immediately after the antenna, instead of simply synthesizing the received radio waves from each antenna. Has been. Tuner characteristic adjustment includes, for example, gain adjustment and setting of a time constant for level detection used for automatic gain control.
JP 2006-319608 A

  As described above, diversity reception is an extremely effective reception method for a portable digital broadcast receiver, but it is disadvantageous in terms of power consumption of the receiver. In order to simultaneously receive and synthesize radio waves received from multiple antennas, it is necessary to amplify radio waves from each antenna and simultaneously operate multiple tuner units to select the desired channel, which increases power consumption. To do. As is well known, the tuner unit in a television broadcast receiving apparatus needs to amplify the UHF band up to 770 MHz, so that the amount of current flowing through the semiconductor element used is large and is usually configured with an analog circuit. Power saving is difficult.

  In recent years, an increase in power consumption for diversity reception is not preferable, while reduction of power consumption of electrical products is strongly demanded from the standpoint of environmental protection. Also, as a portable and portable product, if battery drive is possible, user convenience will be further improved, but if power consumption increases due to diversity reception, this will also conflict with this battery drive. become.

  The present invention has been made in order to solve such problems, and a digital broadcast receiving apparatus and a digital broadcasting apparatus capable of minimizing power consumption of a plurality of tuner sections while maintaining a diversity receiving function. An object is to provide a broadcast receiving method.

  To achieve the above object, a digital broadcast receiving apparatus according to claim 1 of the present invention receives N (N is a natural number of 2 or more) built-in antennas for receiving digital broadcast waves, and receives digital broadcast waves. An antenna input switching unit that switches between an external antenna, an input from any one of the N built-in antennas and an input from the external antenna, and a predetermined broadcast connected to the built-in antenna and the antenna input switching unit. N tuner units that output individual carrier signals having frequencies corresponding to the channels, N power switch units that supply power to each of the N tuner units, and two or more of the N tuner units A carrier synthesizer that outputs a combined carrier signal obtained by combining the individual carrier signals output from the tuner unit, and an individual carrier signal. Is a demodulator that demodulates a video / audio signal from a combined carrier signal, a carrier quality evaluation value detector that detects a quality evaluation value of an individual carrier signal or a combined carrier signal, a detection result of the carrier quality evaluation value detector, and / or an antenna A control unit that selects a predetermined number of tuner units to be used for demodulation based on the antenna input switching information of the input switching unit, and causes the power switch unit to supply power only to the selected number of tuner units. It is characterized by that.

  With such a configuration, not all antennas are used as in normal diversity reception, but the antenna to be used is determined according to the quality of the carrier signal, and a predetermined number of tuner units connected to this antenna. Since power is supplied only to the power source, power consumption can be reduced as compared with normal diversity reception.

  The digital broadcast receiving apparatus according to claim 2 of the present invention is the digital broadcast receiving apparatus according to claim 1, wherein the control unit has a quality evaluation value of an individual carrier signal output from any one of the N tuner units. When the value is equal to or greater than the predetermined reference value, the tuner unit that outputs the individual carrier signal with the maximum quality evaluation value is selected as the tuner unit used for demodulation.

  With such a configuration, normal diversity reception is performed only when none of the external antennas and all the built-in antennas has a detected value of the individual carrier C / N that satisfies the reference value. If there is one that satisfies the reference value, power is supplied only to the tuner unit connected to the antenna and the output carrier is used for demodulation, and the power of the tuner unit connected to the other antenna is Since all are turned off, it is possible to reduce power consumption compared to normal diversity reception.

  The digital broadcast receiver according to claim 3 of the present invention is the digital broadcast receiver according to claim 1, wherein the control unit is M of N tuner units (M is a natural number of 2 or more and less than N). The quality evaluation value of the combined carrier signal from the tuner unit is detected, and if any of the M combinations has a quality evaluation value equal to or higher than a predetermined reference value, the combination of the M tuner units is combined. A combination of M tuner units that maximize the quality evaluation value of the carrier signal is selected as a tuner unit to be used for demodulation.

  With such a configuration, when all of the N built-in antenna carriers C / N do not satisfy the reference value, the carrier of all N built-in antennas is not combined but the carrier of the M antennas is combined. If the combination carrier C / N of any combination satisfies the reference value, broadcast reception is performed with the combination carrier of the combination, and the power of the tuner unit connected to the other built-in antenna is turned off. As a result, power consumption can be reduced as compared with normal diversity reception using all N antennas.

  According to a fourth aspect of the present invention, there is provided a digital broadcast receiving apparatus according to the first aspect, wherein the control unit is configured to transmit an antenna when the antenna input switching unit is switched to an input from an external antenna. A tuner unit connected to the input switching unit is selected as a tuner unit used for demodulation.

  With this configuration, when there is an external antenna connection, diversity reception by the built-in antenna is not performed, and only the external RF input signal from the external antenna is used for demodulation. Therefore, the power of the tuner unit other than the tuner unit connected to the external antenna can be turned off, so that power consumption can be reduced and stable reception is possible because the external RF input signal is used.

  The digital broadcast receiver according to claim 5 of the present invention is the digital broadcast receiver according to claim 1, wherein the antenna input switching unit further includes a signal detection function for detecting an input signal from the external antenna, When an input signal from the external antenna is detected, the input is switched to the input from the external antenna, and when the input signal from the external antenna is not detected, the input is switched to the input from the built-in antenna.

  With such a configuration, the external antenna is automatically selected only when the external RF input signal is detected and there is an external RF input signal, so that the user does not need to perform an input switching operation. Further, there is no possibility of selecting an external antenna by mistake even when there is no external RF input signal.

  The digital broadcast receiver according to claim 6 of the present invention is the digital broadcast receiver according to any one of claims 1 to 5, wherein the control unit periodically monitors the quality evaluation value during broadcast reception. When the quality evaluation value falls below a predetermined reference value, N power switch units are controlled again.

  With such a configuration, the carrier C / N for diversity reception is periodically evaluated during reception of broadcast radio waves, so that power consumption can be reduced even when the broadcast radio wave reception status of the digital broadcast receiver changes. The reception quality can be ensured.

  A digital broadcast receiving apparatus according to claim 7 of the present invention is the digital broadcast receiving apparatus according to any one of claims 1 to 6, wherein the control information of the N power switch units is stored for each broadcast channel. And the control unit controls the N power switch units using the control information of the broadcast channel read from the storage unit when the broadcast channel is selected.

  With such a configuration, even when the reception channel is changed during reception of broadcast radio waves, it is possible to reliably and quickly set optimal diversity reception because the past control information of diversity reception control is used. Further, if the control information is stored in a volatile memory such as a RAM, inappropriate control information is used even when the user turns off the main power and moves the digital broadcast receiving apparatus to another location. There is nothing.

  The digital broadcast receiving apparatus according to claim 8 of the present invention is the digital broadcast receiving apparatus according to any one of claims 1 to 7, wherein the quality evaluation value is a C / N value of an individual carrier signal or a combined carrier signal. It is characterized by being. With such a configuration, the quality of the carrier signal can be accurately evaluated.

  According to a ninth aspect of the present invention, there is provided a digital broadcast receiving method comprising N built-in antennas (N is a natural number of 2 or more) for receiving digital broadcast waves, and an external antenna for receiving digital broadcast waves. A method for receiving digital broadcasting in an apparatus, comprising: supplying power only to a tuner unit connected to an external antenna; detecting a quality evaluation value of an individual carrier signal of a tuner unit connected to an external antenna; If the quality evaluation value of the individual carrier signal of the tuner unit connected to the connected external antenna is equal to or higher than the predetermined reference value, the channel selection operation is performed with the tuner unit connected to the external antenna, and less than the predetermined reference value. In the case of, the step of supplying power to the tuner unit connected to the built-in antenna and the connection to the built-in antenna Detecting the quality evaluation value of the individual carrier signal of the selected tuner unit and, if the quality evaluation value of the individual carrier signal of the tuner unit connected to the detected built-in antenna is equal to or higher than a predetermined reference value, the quality evaluation The tuning operation is performed only with the tuner unit having the maximum quality evaluation value among the values, and the power supply to the tuner units other than the tuner unit is stopped. If the value is less than the predetermined reference value, the predetermined number of tuner units are used. Performing the channel selection operation.

  According to the present invention, it is possible to provide a digital broadcast receiving apparatus and a digital broadcast receiving method capable of minimizing power consumption of a plurality of tuner units while maintaining a diversity reception function.

  Hereinafter, a digital broadcast receiving apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a digital broadcast receiving apparatus according to the present invention. As shown in FIG. 1, the digital broadcast receiving apparatus includes N built-in antennas 100 (1) to 100 (N), N tuner units 170 (1) to 170 (N), a carrier combining unit 201, A demodulation unit 202, a video / audio decoder unit 203, a combined carrier C / N detection unit 204 as a combined carrier quality evaluation value detection unit, a CPU 205 as a control unit, a system bus 206, and a RAM 207 as a storage unit; An external antenna connection terminal 121 and an antenna input switching unit 122 are provided. The tuner unit 170 (1) includes a tuner unit 130 (1), a carrier switch unit 140 (1), an individual carrier C / N detection unit 150 (1) as an individual carrier quality evaluation value detection unit, and a power switch. Part 160 (1). The other tuner units 170 (2) to 170 (N) have the same configuration.

  Broadcast radio waves received by the N built-in antennas 100 (1) to 100 (N) are input to the tuner units 130 (1) to 130 (N), respectively. Since the built-in antennas 100 (1) to 100 (N) are prepared for diversity reception, they are arranged at appropriate intervals in the digital broadcast receiving apparatus and are often installed with different directivities. . Tuner units 130 (1) to 130 (N) amplify the received broadcast radio wave, selectively take out a desired broadcast channel based on the result of channel selection by the user, and have a carrier having a predetermined frequency after channel selection. A signal (hereinafter also simply referred to as “carrier”) is output. In consideration of ease of processing in the subsequent stage, etc., it is generally converted to a so-called intermediate frequency and output. The specific value of N is determined in consideration of the price of the product and the like, but about 2 to 4 is preferable in practical use.

  Here, in addition to the built-in antenna 100 (N), an external antenna connection terminal 121 is prepared for the Nth tuner unit 130 (N) so that the external antenna 110 can be connected. Which of the built-in antenna 100 (N) and the external antenna 110 is used as the input of the tuner unit 130 (N) is switched by the antenna input switching unit 122. This switching may be electronically performed by the user on the digital broadcast receiving apparatus using a remote controller or a main body operation unit. For simplicity, a mechanical switch mechanism is provided in the antenna input switching unit 122 so that the user can manually perform the switching. May be switched mechanically.

  Since the external antenna 110 is normally installed on the roof of a house or the roof of a building, it has a superior reception environment and can receive broadcast waves more stably than the built-in antennas 100 (1) to 100 (N). If the user subscribes to CATV, it is also possible to connect a CATV pull-in signal to the external antenna connection terminal 121.

  Output carriers of tuner units 130 (1) to 130 (N) are input to carrier switch units 140 (1) to 140 (N), respectively. The carrier switch units 140 (1) to 140 (N) are provided to control whether or not the output carrier from each tuner unit is used for diversity combining, and functionally, a high frequency that conducts and blocks the carrier. Switch.

  The output carriers of the tuner units 130 (1) to 130 (N) are also input to the individual carrier C / N detection units 150 (1) to 150 (N), respectively. In the individual carrier C / N detection units 150 (1) to 150 (N), do the output carriers from the respective tuner units 130 (1) to 130 (N) have sufficient quality for receiving digital broadcasts? Whether or not the carrier CNR (Carrier to Noise Ratio: hereinafter referred to as “C / N”) is detected and evaluated. Specifically, the determination is made by comparing with a predetermined reference value. The parameter for evaluating the carrier quality may simply be the signal strength of each carrier. The output carriers of the N carrier switch units 140 (1) to 140 (N) are input to the carrier combining unit 201 and are combined (carrier addition). The combined carrier is taken out as video output and audio output via the demodulator 202 and the video / audio decoder unit 203.

  The demodulator 202 performs an operation of demodulating a carrier of a digitally modulated broadcast signal, and performs digital modulation used for digital broadcasting, for example, multilevel QAM (Quadrature Amplitude Modulation) or OFDM.

  The video / audio decoder unit 203 performs processing for reproducing the demodulated data demodulated by the demodulating unit 202 into a bit stream into video and audio signals. A specific configuration example of the video / audio decoder unit 203 is shown in FIG. As shown in FIG. 2, the input bit stream is first corrected for transmission errors at the time of broadcast reception by the error correction unit 231, and then necessary video and audio from the TS signal by the TS (Transport Stream) decoder unit 232. Information is extracted. Finally, the AV decoder unit 233 performs decoding of compressed data such as MPEG (Moving Picture Experts Group) 2 and D / A conversion as necessary, converts the signal into an externally usable signal form, and outputs the signal.

  The synthesized carrier synthesized by the carrier synthesizing unit 201 is also input to the synthesized carrier C / N detecting unit 204, the C / N of the synthesized carrier is detected, and the detected synthesized carrier C / N is taken into the CPU 205 and digital broadcasting is performed. It is evaluated whether it has sufficient quality for reception. The evaluation is the same as the individual carrier C / N detection units 150 (1) to 150 (N), and is performed by comparing the combined carrier C / N with a predetermined reference value determined in advance.

  The CPU 205 acquires detection results of the individual carrier C / N detection units 150 (1) to 150 (N) and the combined carrier C / N detection unit 204, determines an antenna and a tuner unit used for diversity reception, and determines each tuner. The power supply to the units 170 (1) to 170 (N) is controlled. Each of the tuner units 170 (1) to 170 (N) is provided with a power switch unit 160 (1) to 160 (N), respectively, which receives control from the CPU 205 via the system bus 206 and transfers it to the corresponding tuner unit. Supply (ON) or stop (OFF) the power. With this mechanism, power is supplied only to the necessary tuner units, so that the power consumption of the digital broadcast receiving apparatus can be reduced.

  The tuner units 130 (1) to 130 (N), the carrier switch units 140 (1) to 140 (N), and the individual carrier C / N detection unit 150 (in each tuner unit 170 (1) to 170 (N). 1) to 150 (N) and the power switch units 160 (1) to 160 (N) are all given control signals from the system bus 206, and conversely send internal information to the system bus 206. In FIG. 1, for convenience, a control line is not individually described for each, but one control line is described for the entire tuner unit.

  Next, the operation of the digital broadcast receiving apparatus in this embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing the flow of diversity reception control processing in the digital broadcast receiving apparatus of the present embodiment. First, in step S101, in a series of channel selection operations of the digital broadcast receiver, such as channel selection by a user channel selection operation, channel selection by reservation execution, and channel selection for program information storage, the CPU 205 performs an antenna input switching unit by the user. The setting state 122 is read. When the user electronically sets the digital broadcast receiving apparatus with the remote controller or the main body operation unit, the contents of a storage unit (not shown) such as a nonvolatile memory in which the setting value is stored are read. When a mechanical switch mechanism is attached to the antenna input switching unit 122 and the user performs a mechanical switching operation manually, the setting of antenna selection can be detected by detecting the mechanical position.

  If it is detected in step S101 that the external antenna 110 has been set, the antenna input switching unit 122 selects an external RF (Radio Frequency) input from the external antenna 110 in step S102. If the external antenna 110 is connected, it is only necessary to operate the Nth tuner unit 170 (N) under the condition that the external antenna 110 is used. The power sources of the units 170 (1) to 170 (N-1) are turned off, and the power source of the Nth tuner unit 170 (N) is subsequently turned on in step S104. These operations are executed by the power switch units 160 (1) to 160 (N) in response to instructions from the CPU 205.

  Next, in step S105, only the carrier switch unit 140 (N) of the Nth tuner unit 170 (N) is turned on to set the carrier combining unit 201 to a non-combining setting. In this case, only the output carrier from tuner unit 170 (N) is used for demodulation by demodulation section 202. This operation is executed by the carrier switch sections 140 (1) to 140 (N) in response to an instruction from the CPU 205.

  When the power switch units 160 (1) to 160 (N) and the carrier switch units 140 (1) to 140 (N) are subjected to predetermined control, channel selection processing is performed in step S106, and reception processing for a desired broadcast channel is performed. Be started. Specifically, the operations of the demodulation unit 202 and the video / audio decoder unit 203 are started. The channel selection processing here includes not only channel selection but also processing for changing various parameters (such as filter constants) of the tuner units 130 (1) to 130 (N).

  On the other hand, if it is detected in step S101 that the built-in antenna is set, the input from the built-in antenna 100 (N) is selected by the antenna input switching unit 122 in step S112.

  When receiving with only the built-in antenna, normal diversity reception (reception using all the built-in antennas) is performed, so in step S113, all tuner units 170 (1) to 170 (N) are turned on. To do. Thereafter, in step S114, all the carrier switch units 140 (1) to 140 (N) are turned on so that the carrier combining unit 201 is set to combine all carriers. After the above control is completed, a channel selection process is performed in step S106, a reception process for a desired broadcast channel is started, and the process ends.

  The process flow is substantially the same as above, but the antenna input selection setting is not performed by the user setting information, but whether the external antenna 110 is connected to the external antenna connection terminal 121, that is, whether an external RF signal is input. FIG. 4 shows a method of automatically detecting whether and performing diversity reception control using the detection result. In FIG. 4, in step S121, if the external antenna connection terminal 121 has an external antenna connection, the process proceeds to step 102, and if there is no external antenna connection, the process proceeds to step S112. The subsequent processing flow is the same as in FIG.

  Thus, according to the digital broadcast receiving apparatus in the present embodiment, when there is an external antenna connection, diversity reception by the built-in antenna is not performed, and only the external RF input signal from the external antenna is used for demodulation. Therefore, the power of the tuner unit other than the tuner unit connected to the external antenna can be turned off, so that power consumption can be reduced and stable reception is possible because the external RF input signal is used. Furthermore, since an external antenna is automatically selected only when an external RF input signal is detected and there is an external RF input signal, there is no need for the user to perform an input switching operation. Further, there is no possibility of selecting an external antenna by mistake even when there is no external RF input signal.

(Second Embodiment)
Next, a digital broadcast receiving apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a flowchart showing a flow of diversity reception control processing in the digital broadcast receiving apparatus of the present embodiment. The digital broadcast receiving apparatus according to the present embodiment first checks whether sufficient reception quality can be obtained with only the external antenna, and if sufficient reception quality is obtained, receives with the external antenna. Check whether one built-in antenna can provide sufficient quality. If sufficient reception quality is obtained, receive with this built-in antenna, and if it is not enough, finally receive diversity with normal built-in antenna. Is to do.

  First, in step S202, the antenna input switching unit 122 is switched to the external antenna input side, and an external RF input signal from the external antenna 110 is selected as an input of the Nth tuner unit 170 (N). Subsequently, in step S203, the 1st to (N-1) th tuner units 170 (1) to 170 (N-1) are turned off, and in step S204, the Nth tuner unit 170 (N) is turned on. Thereafter, in step S205, only the carrier switch unit 140 (N) of the Nth tuner unit 170 (N) is turned on to set the carrier synthesizing unit 201 to non-combining, and the output carrier from the tuner unit 170 (N) is demodulated. The unit 202 is used.

  After performing the channel selection process in step S206, the individual carrier C / N is detected by the individual carrier C / N detection unit 150 (N) of the Nth tuner unit 170 (N) in step S207, and the detected individual carrier is detected. If C / N is equal to or greater than the reference value, broadcast reception is started and the process is terminated.

  If the individual carrier C / N detected in step S207 does not reach the reference value, the built-in antenna 100 (N) is selected as the antenna input of the Nth tuner unit 170 (N) in step S211. The power of the tuner units 170 (1) to 170 (N-1) is turned on (the power of the tuner unit 170 (N) is already turned on in step S104). Next, after performing a channel selection process in step S213, in step S214, the individual carrier C is detected by the individual carrier C / N detectors 150 (1) to 150 (N) of the tuner units 170 (1) to 170 (N). / N is detected, and it is investigated whether any one satisfies the reference value. If there is even one satisfying the reference value, the process proceeds to step S215, and the power switch sections 160 (1) to 160 (N) are set so that the tuner units other than the tuner unit that obtains the maximum C / N are turned off. In step S216, the carrier switch units 140 (1) to 140 (N) are controlled so as to turn on only the carrier switch of the tuner unit that obtains the maximum C / N in step S216, and the carrier synthesis unit 201 is not synthesized. Set. Thereafter, broadcast reception is started and the process is terminated.

  On the other hand, if each of the individual carriers C / N is less than the reference value in step S214, the process proceeds to step S221, where the carrier switch units 140 (1) to 140 (N) are turned on, and the carrier synthesis unit 201 is turned on for all the tuner units. It is set to synthesize output carriers 170 (1) to 170 (N). Thereafter, the process proceeds to step S222, the channel selection process is executed again, and various parameters of the tuner units 130 (1) to 130 (N) are tuned. Then, broadcast reception is started and the process is terminated. In order to select the maximum one among the plurality of individual carriers C / N, it is necessary to temporarily store the plurality of detected individual carriers C / N. For this purpose, the RAM 207 is used.

  As described above, according to the digital broadcast receiving apparatus in the present embodiment, normal diversity reception is performed for any one of the external antenna and all the built-in antennas whose detected value of the individual carrier C / N satisfies the reference value. This is only the case. If there is one that satisfies the reference value, power is supplied only to the tuner unit connected to the antenna and the output carrier is used for demodulation, and the power of the tuner unit connected to the other antenna is Since all are turned off, it is possible to reduce power consumption compared to normal diversity reception.

(Third embodiment)
Next, a digital broadcast receiving apparatus according to the third embodiment of the present invention will be described with reference to FIGS. 6 and 7 are flowcharts showing the flow of diversity reception control processing in the digital broadcast receiving apparatus of this embodiment. In this embodiment, N = 4 for convenience of explanation. The digital broadcast receiving apparatus according to the present embodiment selects two built-in antennas from the four built-in antennas for diversity reception, and, as in the second embodiment, detects the detected composite carrier C. In order to select the maximum one of / N, a plurality of detected composite carriers C / N are temporarily stored in the RAM 207.

  Steps S202 to S216 in FIG. 6 are the same processing as in FIG. That is, in steps S202 to S207, it is checked whether or not sufficient reception quality can be obtained with the external antenna 110. If the individual carrier C / N is equal to or higher than the reference value, only the tuner unit 170 (4) connected to the external antenna 110 is checked. Supply power and start receiving broadcasts. When sufficient reception quality cannot be obtained with the external antenna 110 (when the individual carrier C / N is less than the reference value), sufficient reception quality is obtained with any one of the built-in antennas in steps S211 to S216. If the individual carrier C / N satisfies the reference value even with one built-in antenna, supply power only to the tuner unit connected to the built-in antenna with the largest individual carrier C / N. And start receiving the broadcast. All other tuner units are turned off.

  If the individual carrier C / N does not exceed the reference value in any tuner unit in step S214, the process proceeds to step S301 in FIG. Steps S301 to S321 check whether the combined carrier C / N of the two built-in antennas out of the four built-in antennas exceeds the reference value, and if so, supply power only to the corresponding tuner unit. The operation to perform is realized. There are six combinations for selecting two built-in antennas from four built-in antennas. For simplicity of explanation, the combination of built-in antennas 100 (1) and 100 (2) is selected, Two candidates for selecting a combination of antennas 100 (3) and 100 (4) are candidates.

  In step S301, the tuner units 170 (3) and 170 (4) are powered off. Since all the tuner units 170 (1) to 170 (4) are powered on before entering step S301, the tuner units 170 (1) and 170 (2) remain in the power-on state. In step S302, the carrier switch units 140 (1) and 140 (2) are turned on, and after channel selection processing in step S303, the carrier combining unit 201 combines only the output carriers of the tuner units 170 (1) and 170 (2). In step S304, the combined carrier C / N detection unit 204 detects the combined carrier C / N. As a result, if the combined carrier C / N exceeds the reference value, the detected value of the combined carrier C / N is stored in the RAM 207 in step S305.

  Next, in S306 to S311, the same is performed for the tuner units 170 (3) and 170 (4). If it is determined in step S310 that the combined carrier C / N of the tuner units 170 (3) and 170 (4) has also exceeded the reference value, the combined carrier C / N is stored in the RAM 207 in step S311. Next, in step S312, the two types of combined carrier C / N stored in the RAM 207 are read out and compared, and the combination with the larger combined carrier C / N is selected. When the combined carrier C / N of the tuner units 170 (3) and 170 (4) is larger, the tuner units 170 (3) and 170 (4) are already supplied with power at that time, and the channel selection is performed. Since the process is finished, the broadcast reception is started immediately and the process is terminated. Conversely, if the combined carrier C / N of the tuner units 170 (1) and 170 (2) is larger, the channel selection process is performed after the power switch and the carrier switch are controlled in steps S313 to S316. To start broadcast reception and end the process.

  On the other hand, if the combined carrier C / N of the tuner units 170 (1) and 170 (2) falls below the reference value in step S304, the tuner units 170 (3) and 170 (4) are in steps S317 to S321. It is checked whether the synthetic carrier C / N exceeds the reference value. If it exceeds, broadcast reception is started using the combined carrier of the tuner units 170 (3) and 170 (4) as it is, and the process ends. If the combined carrier C / N of the tuner units 170 (3) and 170 (4) is also below the reference value, the power is supplied to all the tuner units 170 (1) to 170 (4) through steps S401 to S403, Broadcast reception is started with the composite carrier of, and the process is terminated.

  As described above, according to the digital broadcast receiving apparatus of this embodiment, when all of the four built-in antenna carriers C / N do not satisfy the reference value, the four built-in antenna carriers are not combined. First, a carrier is combined with a combination of two antennas, and if the combined carrier C / N of any combination satisfies the reference value, broadcast reception is performed with the combined carrier of the combination, and the other two built-in antennas Turn off the tuner unit connected to the. As a result, power consumption can be reduced as compared with normal diversity reception using all four antennas.

(Fourth embodiment)
Next, a digital broadcast receiving apparatus according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a flowchart showing a flow of diversity reception control processing in the digital broadcast receiving apparatus of the present embodiment. The digital broadcast receiving apparatus of the present embodiment, for example, even when the radio wave environment changes during broadcast reception and the status of the received radio wave changes, the diversity reception control is changed to follow the status of the received radio wave, and is always stable. To receive broadcasts.

  In FIG. 8, first, in step S501, the user setting state of the antenna input switching unit 122 is checked. If the external antenna 110 is selected, the individual tuner unit 170 (N) to which the external antenna 110 is connected in step S502. Carrier C / N detector 150 (N) detects individual carrier C / N. If the built-in antenna is selected, it is detected in step S503 whether power is supplied only to a single tuner unit or whether power is supplied to all tuner units 170 (1) to 170 (N). If power is supplied to a single tuner unit, the individual carrier C / N of the corresponding tuner unit is supplied in step S504, and power is supplied to all tuner units 170 (1) to 170 (N). In this case, the composite carrier C / N is detected in step S505. If they exceed the reference value, the process is terminated without performing any process, and after waiting for a fixed time in step S507, the process returns to the beginning, and the next opportunity is confirmed.

  On the other hand, if the carrier C / N or the combined carrier C / N of the tuner unit currently selected is below the reference value in step S502, S504, or step S505, the process proceeds to step S506, and antenna selection is performed again. Step S506 is a processing flow according to the flowchart of FIG. As described above, through the processing flow of FIG. 5, the selection result that can maintain the carrier quality can be selected again in the order of the use of the external antenna, the use of any one of the built-in antennas, and the use of all the built-in antennas. Even when the situation changes, the reception quality can be recovered.

  A partial modification flow of the flowchart of FIG. 8 is the flowchart of FIG. Differences from the flowchart of FIG. 8 will be described. Step S601 is a process for detecting the number of tuner units that are powered on, as in step S503 in FIG. 8. In FIG. 8, one or all (N) tuner units are detected. Then, the number is one or more than two. As described in the flowchart of FIG. 7, it is assumed that there are M (M is 2 or more and less than N) between one or all (N). Therefore, step S603 is assumed to be not only the evaluation of the composite carrier by all the tuner units 170 (1) to 170 (N) as in step S505 in FIG.

  Naturally, the reception quality recovery step S604 when the radio wave condition is changed is also a subdivided recovery process as shown in FIGS. That is, the case of the external antenna corresponds to the case of one built-in antenna, the case of M built-in antennas (explained with two in FIG. 7), and the case of all the built-in antennas (explained with four in FIG. 7). .

  As described above, according to the digital broadcast receiving apparatus of the present embodiment, the quality evaluation value (carrier C / N) of diversity reception is periodically evaluated during the reception of broadcast radio waves. Even when the reception status of radio waves changes, it is possible to ensure reception quality while reducing power consumption.

(Fifth embodiment)
Next, a digital broadcast receiving apparatus according to the fifth embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a flowchart showing a flow of diversity reception control processing in the digital broadcast receiving apparatus of the present embodiment. The digital broadcast receiving apparatus according to the present embodiment stores, for example, once-determined diversity reception control information in the RAM 207 together with the reception channel, and reads the control information stored in the RAM 207 when the same broadcast channel is received next time. By using this, the control responsiveness is improved.

  In general, the combination of antennas to be used is different for each desired broadcast channel, and the combination of the control results of the reception channel and the antenna to be used (used tuner unit) is, for example, as shown in FIG. The receiving antenna is determined for each of the 1 to 10 broadcast channels, and as a result, the tuner unit for turning on the power is determined. In the example of FIG. 11, all the built-in antennas 100 (1) to 100 (N) are used for the 6th channel and the 8th channel, and two built-in antennas are used for the 1st channel, the 4th channel, and the 9th channel. One internal antenna is used, and the external antenna 110 is used for the 2nd and 5th channels. If the relationship between such a broadcast channel and a receiving antenna used for diversity reception is stored in the RAM 207 as a table, when the same channel is received from the next time, this storage table is used as it is, so that FIG. It is possible to set the optimum antenna selection in a short time without performing the processing flow as shown in FIG.

  However, if the main power operation of the digital broadcast receiving apparatus is performed, there is a high possibility that the position or orientation of the digital broadcast receiving apparatus has been changed, so the data in the RAM 207 is not used and the stored data is temporarily stored. It is appropriate to delete. By using a volatile memory such as a RAM for data storage, the stored data is surely erased when the main power is stopped, so that inappropriate control information is not used by mistake.

  The flowchart shown in FIG. 10 shows a processing flow of diversity reception control using the control information stored in the RAM 207 as described above. First, in step S701, channel selection channel information by a user operation is read. With this channel information, the table shown in FIG. If the antenna switching information is the external antenna 110 in step S702, the tuner unit 170 (N) connected to the external antenna 110 is turned on and the carrier switch unit 140 (N ) Is turned on, channel selection processing is performed in step S707, broadcast reception is started, and processing is terminated.

  If the built-in antenna is selected in the RAM information read in step S702, the connection switch to the built-in antenna is switched in step S711, and then the power switch units 160 (1) to 160 (N) are switched based on the RAM information in step S712. In step S713, the carrier switch units 140 (1) to 140 (N) are controlled. In step 714, broadcast reception is started after the channel selection process, and the process ends. For example, when three channels are selected, power is supplied only to the tuner unit 170 (3), the carrier switch unit 140 (3) is turned on, and demodulation is performed using only this output carrier. For example, when 4 channels are selected, power is supplied to the tuner units 170 (3) and 170 (4), and the carrier switch units 140 (3) and 140 (4) are turned on. Two output carriers are combined and demodulated with the combined carrier.

  As described above, according to the digital broadcast receiving apparatus of the present embodiment, even when the reception channel is changed during the reception of the broadcast radio wave, the past diversity control information is used, so that the optimum diversity reception can be performed quickly and reliably. Can be set. In addition, since control information is stored in a volatile memory such as RAM, inappropriate control information should be used even when the user turns off the main power and moves the digital broadcast receiver to another location. There is no.

  As described above, according to the present invention, digital broadcast reception that effectively reduces power consumption by supplying power to only the minimum necessary tuner unit while maintaining stable reception performance by diversity reception. An apparatus can be provided.

  In the above embodiment, the carrier C / N is used as the quality evaluation parameter of the individual carrier and the combined carrier. However, if the carrier level is used, the detection circuit and the like can be further simplified. Further, a parameter such as a reception error rate acquired by the demodulation unit 202 may be used as the quality evaluation parameter. In this case, it is possible to evaluate the carrier quality with higher reliability.

  In the above embodiment, two types of carrier C / N detection units, ie, an individual carrier C / N detection unit and a combined carrier C / N detection unit, are provided for carrier quality evaluation. The part can also be used for individual carrier C / N detection. That is, the carrier switch unit of each tuner unit may be switched over at a predetermined time to make a round, and the individual carrier C / N may be detected by time division.

  In the above-described embodiment, it has been described that the power supply control of the tuner unit is performed as needed during the evaluation of the carrier C / N for diversity reception control in addition to the diversity reception. Because it is a short time, power is supplied to all tuner units during the carrier C / N evaluation, and the power is controlled when control information for diversity reception is obtained (the power of unnecessary tuner units is turned off). Off). Thereby, it is not necessary to frequently switch the power switch of the tuner unit, and the control can be simplified.

  The present invention can be widely used not only for portable digital broadcast receivers with built-in antennas but also for portable terminal devices that receive digital broadcasts.

The block diagram which shows the structure of the digital broadcast receiver of this invention Specific configuration diagram of video / audio decoder unit of the present invention The flowchart which shows the process sequence of the diversity reception control in the 1st Embodiment of this invention. The flowchart which shows the other example of the process sequence of the diversity reception control in the 1st Embodiment of this invention. The flowchart which shows the process sequence of the diversity reception control in the 2nd Embodiment of this invention. The flowchart which shows the process sequence of the diversity reception control in the 3rd Embodiment of this invention. The flowchart which shows the process sequence of the diversity reception control in the 3rd Embodiment of this invention. The flowchart which shows the process sequence of the diversity reception control in the 4th Embodiment of this invention. The flowchart which shows the other example of the process sequence of the diversity reception control in the 4th Embodiment of this invention. The flowchart which shows the process sequence of the diversity reception control in the 5th Embodiment of this invention. The figure which shows the example of the control table in the 5th Embodiment of this invention

100 (1) to 100 (N) Built-in antenna 110 External antenna 121 External antenna connection terminal 122 Antenna input switching unit 130 (1) to 130 (N) Tuner unit 140 (1) to 140 (N) Carrier switch unit 150 (1 ) To 150 (N) Individual carrier C / N detection unit 160 (1) to 160 (N) Power switch unit 170 (1) to 170 (N) Tuner unit 201 Carrier synthesis unit 202 Demodulation unit 203 Video / audio decoder unit 204 Synthesis Carrier C / N detection unit 205 CPU
206 System bus 207 RAM
231 Error correction unit 232 TS decoder unit 233 AV decoder unit

Claims (9)

N (N is a natural number of 2 or more) built-in antennas for receiving digital broadcast waves;
An external antenna for receiving digital broadcast waves;
An antenna input switching unit that switches between an input from any one of the N built-in antennas and an input from the external antenna;
N tuner units that are connected to the built-in antenna and the antenna input switching unit and output individual carrier signals having frequencies corresponding to predetermined broadcast channels;
N power switch units for supplying power to each of the N tuner units;
A carrier combining unit that outputs a combined carrier signal obtained by combining individual carrier signals output from two or more tuner units of the N tuner units;
A demodulator that demodulates a video and audio signal from the individual carrier signal or the combined carrier signal;
A carrier quality evaluation value detector for detecting a quality evaluation value of the individual carrier signal or the combined carrier signal;
Based on the detection result of the carrier quality evaluation value detection unit and / or the antenna input switching information of the antenna input switching unit, a predetermined number of tuner units to be used for demodulation are selected, and the power switch unit selects the selected predetermined unit A control unit for supplying power only to a number of tuner units;
A digital broadcast receiver characterized by comprising: The control unit outputs an individual carrier signal that maximizes the quality evaluation value when the quality evaluation value of the individual carrier signal output from any one of the N tuner units is equal to or greater than a predetermined reference value. The digital broadcast receiving apparatus according to claim 1, wherein the tuner unit to be used is selected as a tuner unit to be used for demodulation. The control unit detects a quality evaluation value of a composite carrier signal from M tuner units (M is a natural number of 2 or more and less than N) out of the N tuner units, and any one of the M combinations includes: When the quality evaluation value is equal to or greater than a predetermined reference value, among the combinations of the M tuner units, M tuner units having a combination that maximizes the quality evaluation value of the combined carrier signal are used for demodulation. The digital broadcast receiving apparatus according to claim 1, wherein the digital broadcast receiving apparatus is selected as a tuner unit. When the antenna input switching unit is switched to an input from the external antenna, the control unit selects a tuner unit connected to the antenna input switching unit as a tuner unit used for demodulation. The digital broadcast receiving apparatus according to claim 1, wherein: The antenna input switching unit further includes a signal detection function for detecting an input signal from an external antenna. When an input signal from the external antenna is detected, switching to the input from the external antenna is performed. The digital broadcast receiving apparatus according to claim 1, wherein when the input signal is not detected, the input is switched to the input from the built-in antenna. The control unit periodically monitors the quality evaluation value during broadcast reception, and controls the N power switch units anew when the quality evaluation value falls below a predetermined reference value. The digital broadcast receiving apparatus according to claim 1, wherein the digital broadcast receiving apparatus is a digital broadcast receiving apparatus. A storage unit for storing control information of the N power switch units for each broadcast channel;
The said control part controls the said N power switch parts using the said control information of the said broadcast channel read from the said memory | storage part at the time of broadcast channel selection. The digital broadcast receiver according to the item. The digital broadcast receiving apparatus according to claim 1, wherein the quality evaluation value is a C / N value of the individual carrier signal or the combined carrier signal. A digital broadcast receiving method in a digital broadcast receiving apparatus comprising N (N is a natural number of 2 or more) built-in antennas for receiving digital broadcast waves and an external antenna for receiving digital broadcast waves,
Supplying power only to the tuner unit connected to the external antenna;
Detecting a quality evaluation value of an individual carrier signal of a tuner unit connected to the external antenna;
When the detected quality evaluation value of the individual carrier signal of the tuner unit connected to the external antenna is equal to or greater than a predetermined reference value, the tuning operation is performed in the tuner unit connected to the external antenna, If less than the reference value, supplying power to the tuner unit connected to the built-in antenna; and
Detecting a quality evaluation value of an individual carrier signal of a tuner unit connected to the built-in antenna;
When the quality evaluation value of the individual carrier signal of the tuner unit connected to the detected built-in antenna is equal to or higher than a predetermined reference value, the tuning operation is performed only with the tuner unit having the maximum quality evaluation value among the quality evaluation values. A step of stopping power supply to tuner units other than the tuner unit and performing a channel selection operation with a predetermined number of tuner units if less than a predetermined reference value;
A digital broadcast receiving method comprising:

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