JP2000332665A - Diversity receiving apparatus and diversity receiving method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To avoid useless diversity operation when reception condition is good. SOLUTION: Two antenna branches A and B are connected to a changeover switch 5. The operation control unit 4 controls the changeover switch 5 to perform the diversity operation. When the reception state of the branch A is good, the operation control unit 4 turns off the power of the tuner 2b and the digital TV demodulation unit 3a of the branch B, and fixes the changeover switch 5 to the branch A side. Diversity operation is limited and power consumption is reduced. It is also preferable to use the branch B to receive a sub-channel signal. The number of branches may be three or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiving apparatus and method, and more particularly to a technique for efficiently operating a receiving apparatus when receiving conditions are good.

[0002]

2. Description of the Related Art Diversity reception is a technique for selecting an antenna having a good reception state from a plurality of antennas provided in a receiving apparatus. The diversity receiver can prevent the influence of multipath, and is suitably applied to, for example, an in-vehicle television receiver. Although television broadcasting is expected to shift from analog broadcasting to digital broadcasting, diversity technology is also effective in digital television receivers. Here, diversity reception of digital television broadcasting will be mainly described, but the present invention is not limited to digital communication.

[0003] Diversity receivers include an antenna switching type and a post-detection diversity type. For example, JP-A-10-257406 discloses an antenna switching type device. A plurality of antennas are connected to the antenna changeover switch, and a receiving circuit is provided after the changeover switch. By switching the switch, an antenna with a good reception state is searched.

On the other hand, in the post-detection diversity type, a receiving circuit is provided for each of a plurality of antennas. By comparing the signals after detection, an antenna having a good reception state is selected. Therefore, the diversity receiver after detection has high performance because the best antenna can be reliably selected although the device is complicated.

[0005]

SUMMARY OF THE INVENTION Diversity reception is
Maximize its capabilities when reception is poor. However, when reception conditions are good, for example, in a reception condition in which no data error occurs or an error that can be recovered by error correction, it is useless to use a plurality of antennas for diversity reception.

For example, in a post-detection diversity type device, all receiving circuits corresponding to a plurality of antennas operate even when the receiving condition is good, and as a result, power is wasted. Even in the antenna switching type, the antenna switching switch is operating uselessly.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a diversity receiving apparatus that operates efficiently when reception conditions are good.

[0008]

In order to achieve the above object, the present invention provides a diversity receiving apparatus including a plurality of antennas and selecting an antenna having a good reception state from the plurality of antennas. And an operation control unit that changes the number of antennas to be selected for the diversity operation based on the reception state of at least one of the antennas. Preferably, the operation control means reduces the number of antennas to be selected as the reception state becomes better. Also preferably, the operation control means stops the diversity operation by reducing the number of antennas to be selected to one.

According to the present invention, the number of antennas to be selected for the diversity operation is changed based on the reception state. When the reception state is good, the number of antennas to be selected is reduced (diversity operation is restricted). This eliminates the waste that all antennas function for diversity despite good reception conditions.

Preferably, in the diversity receiving apparatus according to the present invention, a receiving circuit is provided for each of the plurality of antennas, and a current is supplied to a receiving circuit corresponding to the remaining antennas other than the selected antenna. The supply is stopped. In this aspect, the present invention is applied to a diversity-type receiving apparatus after detection. By stopping power supply to the receiving circuit, unnecessary power consumption can be reduced.

Preferably, the diversity receiver according to the present invention, when the antenna to be selected is receiving a main channel signal, transmits a sub-channel signal different from the main channel signal using the remaining antennas other than the antenna to be selected. Receive. In this aspect, since the sub-channel signal is received using the remaining antennas excluded from the diversity selection target, the remaining antennas are effectively used.

Here, when there are a plurality of the remaining antennas, it is preferable that the subchannel signals are diversity-received using the antennas. The sub-channel signal can be received well. The sub-channel signal received using the remaining antennas may be a signal of a different type of media from the main channel signal.

Another aspect of the present invention is a diversity receiving method for selecting an antenna having a good reception state from a plurality of antennas and receiving a signal using the selected antenna. Channels are allocated according to the reception state of each channel.
When the same channel is allocated to the above antennas, diversity reception is performed using those antennas. According to this aspect, a plurality of antennas can be used efficiently according to the reception state of each channel. When the reception state is good, waste such as performing diversity reception using more antennas than necessary is eliminated.

Here, the plurality of channels may belong to different types of media. In addition, it is preferable to stop supplying current to a receiving circuit corresponding to an antenna to which a channel has not been assigned, so that power consumption can be reduced.

[0015] The present invention may be applied to digital communication or analog communication. The present invention can be applied to diversity after detection and to other diversity. Further, each aspect of the present invention may be expressed in the form of an apparatus or a method.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration. In the present embodiment, the present invention is applied to a two-branch diversity digital television receiver. Each branch A,
B has an antenna and a receiving circuit, that is, the receiver is a diversity type device after detection.

In FIG. 1, an antenna 1a is provided in a first branch A, and an antenna 1b is provided in a second branch B. The antennas 1a and 1b are connected to tuners 2a and 2b, and the radio waves received by the antennas 1a and 1b are down-converted by the tuners 2a and 2b to baseband signals. The tuners 2a and 2b include an operation control unit 4
Is tuned to the channel set by the user using the input unit 13 under the control of.

The down-converted signal is a digital T
The data is input to V demodulators 3a and 3b, where packet data is demodulated. The packet data is, for example, an MPEG2 TS (Transport Stream) packet. Both demodulators 3
TS packets are input from a and 3b to the changeover switch 5. The changeover switch 5 selects one of the TS packets input from the demodulation units 3a and 3b in accordance with an instruction from the operation control unit 4.

The operation control section 4 is a control section for controlling the diversity operation. The bit error information is input to the operation control unit 4 from the digital TV demodulation units 3a and 3b. Then, the operation control unit 4 instructs the changeover switch 5 to select the demodulation unit having the smaller bit error rate (bit error per unit time).

The TS packet selected by the changeover switch 5 is input to the TS decoder 11. TS packet is T
The S decoder 11 sorts out each program type. And T
The V broadcast packet data is sent to the AV decoder 6, and the data broadcast packet data is sent to the data processing unit 7. The data processed by the AV decoder 6 and the data processing unit 7 is passed to the display processing unit 8.

The display processing section 8 generates an audio signal and a video signal and sends them to the speaker 9 and the display 10.
The display processing unit 8 outputs a television broadcast signal and a data broadcast signal in accordance with an operation of an input unit (not shown) by a user. The data broadcast is, for example, a weather forecast. The display processing unit 8 has a function of storing data broadcast information. When the speaker 9 and the display 10 output the audio and video sent from the display processing unit 8, they are provided to the user.

Next, the features of this embodiment will be described.
The operation control unit 4 performs the first operation based on the bit error information input from the digital TV demodulation unit 3a of the first branch A.
It is determined whether the reception state of the branch A is good. If no bit error has occurred, or if a bit error has occurred within a range that can be recovered by error correction, it is determined that the reception state is good.

If the reception state is good, the operation control section 4 fixes the changeover switch 5 to the digital TV demodulator 3a side. Further, the operation control unit 4 issues an instruction to the tuner (high-frequency unit) 2b and the digital TV demodulation unit 3b of the second branch B, and puts their power supplies in a standby state. As a result, the diversity operation is suppressed and one branch A
The broadcast is received using only the broadcast.

FIG. 2 is a flowchart showing diversity operation control by the operation control unit 4. When the main power of the entire receiver is turned on, first, diversity reception starts (S1). The operation control unit 4 determines whether the bit error rate input from the digital TV demodulation unit 3a is equal to or less than a specified value (S2). This prescribed value is set to an appropriate value within a range in which data can be appropriately recovered by error correction.

If the bit error rate is equal to or less than the specified value, the operation control unit 4 determines whether the power of the digital TV demodulation unit 3b is ON (S3). When the power is ON, the power of the tuner 2b and the power of the demodulation unit 3b are set to standby (S
4). Further, the operation control section 4 fixes the changeover switch 5 to the digital TV demodulation section 3a side (S5). Thereby, the diversity operation is suppressed. Then, it is determined whether or not the main power supply is off (S9). If not, the process returns to S2.

If it is determined in step S3 that the power of the demodulation unit 3b is OFF, the process proceeds to step S9. Therefore, while the reception state of the antenna 1a is good, S2 is YES and S3 is N
It is determined as O, and the suppression of the diversity is continued.

On the other hand, if the bit error rate is greater than the specified value in S2, the power state of the digital TV demodulation unit 3b is
It is determined whether it is N (S6). If it is not ON, the power of the tuner 2b and the digital TV demodulation unit 3b is ON.
Is performed (S7). Further, the operation control section 4 returns the changeover switch 5 to the normal diversity switching control state (S8).
Then, the process proceeds to S9, and returns to S2 unless the main power supply is turned off. As described above, when the reception state deteriorates and the bit error rate exceeds a specified value, the diversity operation is restarted.

In step S6, the power of the demodulation unit 3b is turned off.
If it is determined to be N, the process proceeds directly to S9. Therefore, S2 is NO and S6 is Y until the reception condition becomes good again.
ES, and the diversity operation is continued. The above processing is repeated until the main power is turned off in S9.

As described above, according to the present embodiment, the number of antenna branches is changed for diversity operation based on the reception state (diversity operation is limited). When the reception condition is good, only one branch is used, and the current supply to the other branch is stopped. As a result, unnecessary power consumption can be prevented.

Although the number of branches is two in the apparatus of FIG. 1, the present invention is similarly applied to a case where the number of branches is three or more. In this case, use all branches or 1
Only two-stage switching of whether to use a book branch may be performed. However, more preferably, the number of branches is changed in a plurality of stages according to the reception state.

For example, assume that the number of branches is four. Two branches are added to the apparatus of FIG. 1, and a total of four branches are connected to the changeover switch. The operation control unit controls the changeover switch based on the bit error information obtained from the demodulator, and controls the current supply to each branch. Preferably, four ranks of reception status are set. The better the reception condition, the smaller the number of branches. In the highest rank reception state, one branch is used, that is, the diversity operation is completely suppressed.

As described above, the present invention is similarly applied to a case where the number of antennas is two or more. As in the case of two branches, the power consumption can be reduced by changing the number of branches used in diversity.

In this embodiment, the reception state is determined based on the bit error rate. Instead of this bit error rate, an electric field level may be used, or packet error data may be used. In addition, a parameter indicating the reception status is preferably used.

Although the present embodiment is a receiver of the diversity type after detection, the present invention is also suitably applied to a receiver of the antenna switching type, and advantages such as reduction of the load on the antenna switching switch can be obtained. .

Next, FIG. 3 shows another example of the diversity operation control by the operation control section 4. In the processing of FIG. 2, only the power of the second branch B is turned on / off.
On the other hand, in the processing of FIG. 3, the power of both branches A and B is turned on / off according to the reception state of the other party. FIG.
Is schematically shown in comparison with FIG. 2, but the details are the same as in FIG.

First, when the main power supply is turned on, diversity reception starts (S21). The operation control unit 4 determines whether the bit error rate of the currently used branch is equal to or less than a specified value (S22). The branch in use is a branch on which the changeover switch 5 is switched by the diversity operation.

If the determination in S22 is YES, the operation control section 4 suppresses the diversity operation (S23). The power of the tuner and the demodulation unit of the branch that is not currently in use is set to the standby state. The changeover switch 5 is fixed to the branch in use. That is, the first in S22
If the branch A is in use, the power of the second branch B is turned off, and the switch 5 is fixed to the first branch A. The reverse is true if the second branch B is being used.

Next, it is determined whether or not the bit error rate in the branch in use is equal to or greater than a second specified value (S2).
4). This second specified value is set to be larger than the first specified value of S22. If the bit error rate is less than the second specified value, the suppression of the diversity is continued. On the other hand, if the bit error rate is equal to or more than the second specified value, the suppression of the diversity is released (S25). That is, power is turned on to the tuner and the demodulation unit in the standby state. The changeover switch 5 is returned to the diversity operation state.

The same effect as that of FIG. 2 can be obtained by the operation of FIG. 3 described above. Furthermore, the specified value for canceling the suppression state is set to be larger than the specified bit error rate for suppressing diversity, and hunting is prevented by the hysteresis setting. The same hysteresis setting can be applied to the processing in FIG. 2 and also to other embodiments described below.

Next, another preferred embodiment of the present invention will be described with reference to FIG. In this embodiment, when the number of antenna branches to be selected for diversity is reduced, a sub-channel signal is received using the remaining antenna branches excluded from the selection. As a result, the remaining antenna branches can be used effectively.

In FIG. 4, the input unit 13 is configured so that a user can input two of a main channel and a sub-channel. The input unit 13 is configured to prompt the user to input a sub-channel as appropriate.

In the apparatus shown in FIG. 4, the changeover switch 5 is
Under the control of the operation control unit 4, a switching operation or a through operation is performed. In the switching operation, only the TS packets input from one of the two demodulation units 3a and 3b are passed. In the through operation, the TS packets input from both the demodulation units 3a and 3b are passed as they are.

The apparatus shown in FIG. 4 operates in the same manner as the apparatus shown in FIG. 1 during normal diversity reception. Both tuners 2a, 2b are tuned to the main channel. The operation control unit 4 includes digital TV demodulation units 3a and 3
Using the bit error information input from b, the changeover switch 5 selects the demodulation unit having the smaller bit error rate.

The feature of this embodiment is that the operation control unit 4
Sets the tuner 2b to the sub-channel and controls the changeover switch 5 to through when it determines that the reception state is good. Whether the reception condition is good or not is shown in FIG.
As in the case of the device described above, the determination can be made based on the bit error information obtained from the demodulator 3a. If no bit error has occurred, or if a bit error has occurred within a range that can be recovered by error correction, it is determined that the reception state is good.

If the reception state is good, the operation control unit 4
Tunes the tuner 2b to a subchannel.
Tuner 2a remains tuned to the main channel. The operation control unit 4 causes the changeover switch 5 to perform a through operation. Therefore, the demodulation unit 3a outputs the TS packet of the main channel, the demodulation unit 3b outputs the TS packet of the sub-channel, and the TS data of both channels passes through the changeover switch 5 and is sent to the TS decoder 11.

FIG. 5 is a flowchart showing the diversity operation control by the operation control unit 4 of FIG. When the main power of the entire receiver is turned on, first, diversity reception starts (S10). The operation control unit 4 determines whether the bit error rate input from the digital TV demodulation unit 3a is equal to or less than a specified value (S11). This prescribed value is the same as the value used in the processing of FIG. 2, that is, set to an appropriate value within a range in which data can be appropriately recovered by error correction.

When the bit error rate is equal to or less than the specified value, the operation control unit 4 determines whether the channel setting of the tuner 2b is
It is determined whether it is the same as a (S12). S12 is YES
In the case of (1), the channel of the tuner 2b is set to the sub-channel set by the input unit 13 (S13). Further, the changeover switch 5 is set to the through state (S1).
4), the TS packets from the demodulation units 3a and 3b
It is sent to the S decoder 11. That is, diversity operation is suppressed, and separate channels are received using both branches. Then, it is determined whether or not the main power supply is off (S
18) If not OFF, return to S11.

If it is determined in step S12 that the channel settings of both tuners 2a and 2b are not the same, the process proceeds to step S18. Therefore, while the reception state of the antenna 1a is good, S11 is determined as YES and S12 is determined as NO, the suppression of the diversity is continued, and the reception of the two channels is continued.

On the other hand, if the bit error rate is larger than the specified value in S11, the operation control unit 4 determines whether the channel setting of the tuner 2b is the same as that of the tuner 2a (S1).
5). If S15 is NO, the channel of the tuner 2b is set to the same main channel as the tuner 2a (S16). Further, the operation control section 4 returns the changeover switch 5 to the normal diversity switching control state (S17). Then, the process proceeds to S18, and returns to S11 unless the main power supply is turned off. As described above, when the reception state deteriorates and the bit error rate exceeds a specified value, the diversity operation is restarted.

In step S15, both tuners 2a, 2a
If it is determined that the channel settings of b are the same, the process goes directly to S18.
Proceed to. Therefore, until the reception state becomes good again, S11 is NO and S15 is YES, and the diversity operation is continued. The above processing is repeated until the main power is turned off in S18.

As described above, according to the present embodiment, the number of antenna branches for the diversity operation is reduced from two to one when the reception state is good as in the first embodiment described above. Is reduced. Therefore, the waste that all antennas function for diversity reception despite good reception conditions is eliminated. In particular, in the present embodiment, the remaining branches are used for receiving the sub-channel. By effectively utilizing such branches, it is possible to greatly increase the amount of information that can be obtained.

Although the number of branches is two in the apparatus shown in FIG. 4, the present invention is similarly applied to a case where the number of branches is three or more. In this case, it is preferable that the number of branches allocated to the main channel and the sub-channel is variably set according to the reception state.

For example, assume that the number of branches is four. Two branches are added to the apparatus of FIG. 4, and a total of four branches of demodulators are connected to the changeover switch. The operation control unit controls the changeover switch based on the bit error information obtained from the demodulator and tunes each branch.

In the best reception situation, one branch receives the main channel and the other channels receive the sub-channels. Up to three sub-channels can be received. By stopping current supply to unused branches, power consumption can be reduced.

In accordance with the deterioration of the reception situation, diversity reception of the main channel is performed using two, three or four branches. Note that it is preferable to perform diversity reception also for the subchannel. That is, when diversity reception of the main channel is performed using two branches, diversity reception is performed using the remaining two branches.

As described above, similar to the case of the apparatus of FIG.
In the apparatus shown in FIG. 2, the number of branches may be three or more, and the advantages of the present invention can be similarly obtained.

Next, another preferred embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 6, in this embodiment, four antenna branches A to D are provided. The branches A to D are each composed of an antenna 1
a to 1d and tuners 2a to 2d. Tuner 2
The baseband signals output from a to 2d are input to the software receiver 12. The speaker 9, the display 10, and the input unit 13 are connected to the software receiver 12. The software receiver 12 is a receiver that performs demodulation and decoding by digital signal processing.
The functions from the demodulation unit to the display processing unit in FIGS. 1 and 4 are performed.

In the apparatus shown in FIG. 6, the software receiver 12
Includes the functions (see FIGS. 2 and 5) described in the above embodiment. Therefore, this receiver corresponds to the receiver of the above-described embodiment having four branches.

According to this embodiment, the receiver of the present invention can be realized only by improving a program for an existing software receiver, and it is not necessary to change or add hardware. Therefore, there is an advantage that the receiver of the present invention can be easily realized with a simple configuration.

Further, in the present embodiment, it is also preferable that the apparatus shown in FIG. 6 can be configured to be capable of simultaneously receiving a plurality of media. In this case, it is preferable that the distribution of the branch can be variably set according to the reception state of each of the plurality of media.

Here, it is assumed that the plurality of media are a digital television and a digital radio. FIG. 7 shows an example of branch distribution to both media. If both TV and radio reception conditions are poor, two branches are used for each medium and diversity reception is performed. Note that the reception status of each medium may be determined based on the bit error information as in the above embodiment.

When the reception condition of the television is good and the reception condition of the radio is bad, one branch is allocated to the television broadcast. Diversity reception is performed by allocating two or three branches to a radio broadcast. The tuner of the unused branch is set to a standby state, and the current supply is stopped.

When the receiving condition of the television is poor and the receiving condition of the radio is good, the reverse is the above, that is, the diversity reception of the television is performed, and one branch is assigned to the radio.

When both the television and radio reception conditions are good, one branch is assigned to both the television and the radio. Then, the remaining two branches are set to the standby state. Alternatively, as shown in FIG. 7, each medium may receive two channels using two branches. Other arbitrary distributions are possible as well.

6 and 7 can of course be modified appropriately by those skilled in the art. For example, the number of branches, the number of media types, and the number of branches allocated to each medium can be changed. It is possible to increase the number of ranks in the reception state and change the number of distributions according to the rank.

As described above, the effects of the present invention can be suitably obtained by this embodiment. That is, the waste of performing a diversity operation using a fixed number of antennas in spite of good reception conditions is eliminated. The amount of acquired information can be increased by receiving signals of a plurality of media, and the power consumption can be reduced by setting unnecessary antennas to a standby state.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing a diversity operation control of the apparatus of FIG. 1;

FIG. 3 is a flowchart showing a second example of the diversity operation control of the apparatus shown in FIG. 1;

FIG. 4 is a block diagram showing an overall configuration of another embodiment of the present invention.

FIG. 5 is a flowchart showing diversity operation control of the apparatus of FIG. 4;

FIG. 6 is a block diagram showing an overall configuration of still another embodiment of the present invention.

FIG. 7 is a diagram illustrating an example of branch distribution to reception channels in the device of FIG. 6;

[Explanation of symbols]

1a, 1b antennas, 2a, 2b tuners, 3a,
3b Digital TV demodulation unit, 4 operation control unit, 5 changeover switch, 13 input unit, A first antenna branch,
B Second antenna branch.

Claims (10)

[Claims] 1. A diversity receiving apparatus comprising a plurality of antennas and selecting an antenna having a good reception state from the plurality of antennas, wherein a diversity operation is performed based on a reception state of at least one of the plurality of antennas. A diversity receiving device including operation control means for changing the number of antennas to be selected for the operation. 2. The diversity receiving apparatus according to claim 1, wherein the operation control means reduces the number of antennas to be selected as the receiving state becomes better. 3. The diversity receiving apparatus according to claim 1, wherein the operation control means stops the diversity operation by reducing the number of antennas to be selected to one. . 4. The diversity receiving apparatus according to claim 1, wherein a receiving circuit is provided for each of the plurality of antennas, and a receiving circuit corresponding to a remaining antenna other than the antenna to be selected is provided. A diversity receiving device, wherein current supply to the device is stopped. 5. The diversity receiving apparatus according to claim 1, wherein, when the antenna to be selected receives a main channel signal, a subchannel signal different from the main channel signal by using the remaining antennas other than the selection target. And a diversity receiver. 6. The diversity receiver according to claim 5, wherein, when there are a plurality of the remaining antennas, the sub-channel signal is diversity-received using the antennas. 7. The diversity receiver according to claim 5, wherein the sub-channel signal received using the remaining antenna is a signal of a different type of media from the main channel signal. Diversity receiver. 8. A diversity receiving method for selecting an antenna having a good reception state from a plurality of antennas and receiving a signal using the selected antenna. A diversity receiving method characterized in that, when the same channel is allocated to two or more antennas by this allocation, diversity reception is performed using these antennas. 9. The diversity receiving method according to claim 8, wherein the plurality of channels belong to different types of media. 10. The diversity receiving method according to claim 8, wherein current supply to a receiving circuit corresponding to an antenna to which a channel has not been allocated is stopped.