JP2009290610A - Receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep a reception condition in an entire device preferable even in an environment where the reception condition is easily changeable. <P>SOLUTION: In a receiver, a reception condition calculating portion calculates a reception condition value for representing an antenna reception condition of each antenna by using each matching portion corresponding to each antenna which carries out matching of each antenna by changing a matching constant, and a selecting portion selects an antenna to be subjected to change of the matching constant based on the calculated reception condition value. A change instruction portion instructs the change of the matching constant to the matching portion corresponding to the selected antenna. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a receiving apparatus having a plurality of antennas, and more particularly to a receiving apparatus capable of maintaining a good reception situation as a whole apparatus even in an environment in which the reception situation easily changes.

  In recent years, in-vehicle DTV (digital television) receivers have become widespread, but it is required to stably receive broadcast waves even in such a mobile environment. For example, in frequency division combining diversity using a plurality of antennas, the reception performance is improved by combining the outputs of two or four antenna branches.

  By the way, in such a receiving apparatus, it is necessary to perform impedance matching (hereinafter referred to as “matching”) for each antenna. However, when the frequency band of the broadcast wave to be received is wide, it is difficult to perform good matching in all frequency bands.

  For this reason, a technique for changing a matching constant used for matching for each selected channel has been proposed. For example, Patent Document 1 discloses a technique in which a matching constant corresponding to each channel is prepared in advance, and when a specific channel is selected, matching is performed using the matching constant corresponding to the selected channel. Has been.

JP 2004-228996 A

  However, the technique of Patent Document 1 has a problem that the matching constant cannot be changed because the matching constant is changed only when the channel is changed. In particular, in the case of a receiving device mounted on a vehicle, the reception situation changes significantly according to changes in the traveling speed and traveling direction of the vehicle and changes in the traveling environment.

  For example, even when the user continues to watch a specific channel, a situation occurs in which the reception status of a specific antenna branch is good but the reception status of other antenna branches is bad. Therefore, when the outputs of the respective antenna branches are combined, the overall reception status deteriorates due to the influence of the antenna branch having a poor reception status.

  From these facts, when performing reception using a plurality of antennas, how to realize a receiving apparatus that can maintain a good reception situation as a whole apparatus even in an environment where the reception situation easily changes is significant. It has become a challenge.

  The present invention has been made to solve the above-described problems caused by the prior art. When receiving using a plurality of antennas, the reception status of the entire apparatus can be improved even in an environment where the reception status is likely to change. It is an object of the present invention to provide a receiving apparatus that can keep good.

  In order to solve the above-described problems and achieve the object, the present invention is a receiving apparatus having a plurality of antennas, each of which corresponds to the antenna, and performs matching of the antennas by changing matching constants. A reception status value calculating unit that calculates a reception status value representing the reception status of the antenna for each antenna system; and the matching constant is to be changed based on the reception status value calculated by the reception status value calculating unit. A selection unit that selects the antenna, and a change instruction unit that instructs the matching unit corresponding to the antenna selected by the selection unit to change the matching constant.

  According to the present invention, a matching unit that corresponds to each antenna and performs matching of each antenna by changing a matching constant is used to calculate a reception status value that represents the reception status of the antenna for each antenna system. Based on the situation value, the antenna for which the matching constant is to be changed is selected, and the matching unit corresponding to the selected antenna is instructed to change the matching constant. By improving and improving the reception status of the entire device, there is an effect that the reception status of the entire device can be kept good even in an environment where the reception status is likely to change.

  Exemplary embodiments of a receiving apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings. In the following, the outline of the receiving method according to the present invention will be described with reference to FIG. 1, and then an embodiment of a receiving apparatus to which the receiving method according to the present invention is applied will be described with reference to FIGS. And

  First, the outline of the reception method according to the present invention will be described with reference to FIG. FIG. 1 is a diagram showing an outline of a receiving method according to the present invention. In the figure, four antennas A, B, C, and D are used, and signals received by these four antennas are combined. Moreover, the antenna branch (antenna branch A-antenna branch D) corresponding to each antenna refers to the circuit group provided for every antenna system | strain.

  As shown in the figure, in the reception method according to the present invention, the reception status value for each antenna branch is calculated (see (1) in the figure). Here, the reception status value refers to a numerical value indicating the quality of the reception status such as reception CNR (Carrier to Noise Ratio), reception MER (Modulation Error Ratio), and reception level.

  In this way, by monitoring the reception status value for each antenna branch, the reception status of each antenna branch can be constantly grasped. In the reception method according to the present invention, the antenna for which the matching constant is to be changed is selected by comparing the calculated reception status values (reception status values for each antenna branch) ((2) in the figure). reference).

  For example, when the antenna branch D having the worst reception status among the antenna branches A to D is the antenna branch D, the antenna D is selected as a matching constant change target. Note that it is not necessary to select one antenna, and a plurality of antennas may be selected in order of poor reception status. Further, it is possible to select an antenna whose reception status value is below a predetermined threshold.

  If the antenna for which the matching constant is to be changed is selected, the matching constant of the selected antenna is changed (see (3) in the figure). Note that the matching constants for the unselected antennas are not changed.

  As described above, in the reception method according to the present invention, since the matching constant is changed while grasping the antenna branch in which the reception condition is bad in real time, the reception condition of the antenna branch in which the reception condition is bad may be improved. it can. Therefore, when the signal values from all antennas are combined, the overall reception status can be improved.

  Since each of the above-described processes ((1) to (3) in the figure) is always performed, even if the antenna branch whose reception condition is bad changes every moment due to a change in the reception environment or the like, it is comprehensive. It is possible to maintain a good reception situation.

  Below, the Example about the receiver which applied the reception method which concerns on this invention mentioned above is described. In the embodiment described below, a receiving apparatus mounted on a vehicle such as an automobile and receiving a broadcast wave such as a digital television broadcast wave will be described.

  FIG. 2 is a block diagram illustrating a configuration of the receiving device 10 according to the present embodiment. In the figure, the receiving apparatus 10 having four antennas A, B, C, and D is shown, but the number of antennas can be any number greater than or equal to two. In addition, for example, “A” is added to the end of the code for the elements constituting the antenna branch corresponding to the antenna A, such as the matching unit 11A and the RF / IF 12A. , “B” to “D” are respectively added to the end of the code.

  As shown in the figure, the receiving apparatus 10 includes an antenna (antenna A to antenna D), a matching unit 11, an RF / IF (Radio Frequency) / IF (Intermediate Frequency) 12, and an ADC (Analog Digital Converter) 13. An FFT (Fast Fourier Transform) 14, a reception state monitoring unit 16, a maximum ratio combining unit 17, an error correcting unit 18, and a storage unit 19.

  The reception state monitoring unit 16 further includes a reception state calculation unit 16a, a selection unit 16b, and a change instruction unit 16c, and the storage unit 19 stores saved information 19a. The reception state monitoring unit 16 receives the output of each FFT 14 (FFT 14A to FFT 14D) as an input value via the data branching unit 15 between the FFT 14 / maximum ratio combining unit 17. Each matching unit 11 (matching unit 11A to matching unit 11D) is provided in the vicinity of each corresponding antenna (antenna A to antenna D).

  The matching unit 11 (matching unit 11A to matching unit 11D) performs impedance matching (matching) of the corresponding antenna. Further, the matching unit 11 performs matching by changing the matching constant by changing the capacitance of the variable capacitance diode based on an instruction from the reception state monitoring unit 16.

  Here, a circuit example of the matching unit 11 will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of a circuit configuring the matching unit 11. As shown in the figure, the matching unit 11 includes a coil and a variable capacitance diode, and increases or decreases the capacitance of the variable capacitance diode according to an instruction (for example, voltage change) from the reception state monitoring unit 16.

  In the present embodiment, the matching unit 11 using the variable capacitance diode will be described. However, the matching constant may be changed by a mechanical mechanism that inserts and removes the movable rod into the coil.

  The RF / IF 12 (RF / IF 12A to RF / IF 12D) is a device that detects and amplifies broadcast waves, and performs a process of outputting an amplified IF (Intermediate Frequency) signal to the ADC 13. Further, the ADC 13 (ADC 13A to ADC 13D) performs a process of converting the analog signal received from the RF / IF 12 into a digital signal and outputting the digital signal to the FFT 14.

  The FFT 14 (FFT 14A to FFT 14D) performs a process of performing digital demodulation of an orthogonal frequency division multiplexing system and outputting the result to the maximum ratio combining unit 17. The output result of the FFT 14 is also output to the reception state monitoring unit 16 via the data branching unit 15.

  The reception state monitoring unit 16 calculates the reception state value for each antenna branch based on the output value from each FFT 14 (FFT 14A to FFT 14D), selects the antenna whose matching constant is to be changed, and sets the selected antenna to the selected antenna. This is a processing unit that instructs the matching unit 11 to change the matching constant.

  The reception status value calculation unit 16a calculates a reception status value for each antenna branch based on the output value from each FFT 14 (FFT 14A to FFT 14D), and performs a process of passing the calculated reception status value to the selection unit 16b. It is a processing unit. Here, an outline of the reception status value calculation process performed by the reception status value calculation unit 16a will be described with reference to FIGS.

  FIG. 4 is a diagram illustrating an example of reference points and reception points in a constellation. Here, the constellation is a bit string signal in each antenna branch represented by an in-phase component axis (In-Phase) and a quadrature component axis (Quadrature). Note that (1) in FIG. 4 shows a reference point in the constellation, and (2) in FIG. 4 shows how the reception point in the constellation deviates from the reference point.

  As shown in (1) of FIG. 4, when a digital broadcast wave is transmitted, the transmission data is arranged so as to match a grid-like reference point. However, when a digital broadcast wave is received, each reception point is shifted from each reference point as shown in (2) of FIG. 4 due to the influence of the reception environment or the like. Here, the closer the reception point is to the reference point, the better the reception situation.

  FIG. 5 is a diagram illustrating an example of reception status value calculation. The figure shows the case where the reception status value of each antenna branch is calculated using the reception CNR (Carrier to Noise Ratio), where the black circle represents the reference point and the white circle represents the reception point. ing. Moreover, (A)-(D) of the figure shall respond | correspond to the antenna A-antenna D shown in FIG. 2, respectively.

  As shown in the figure, the distance between a predetermined reference point corresponding to the antenna A and the receiving point is a, the distance corresponding to the antenna B is b, the distance corresponding to the antenna C is c, and the distance corresponding to the antenna D is If d is the largest among a to d, it can be said that the reception status of the antenna D is the worst.

  Here, the distances a to d shown in the figure correspond to the reception CNR. The reception status value calculation unit 16 notifies each distance (a to d) illustrated in FIG. 5 to the selection unit 16b. The selection unit 16b notified of each distance selects an antenna whose matching constant should be changed according to a predetermined selection condition.

  FIG. 5 shows the case where the distance between the reception point and the reference point (corresponding to the reception CNR) is calculated as the reception status value of each antenna branch, but the reception MER (Modulation Error Ratio) and the reception level are calculated. It may be calculated as each reception status value.

  The selection unit 16b is a processing unit that performs processing for selecting an antenna whose reception status is not good, that is, an antenna whose matching constant is to be changed. The selection unit 16b selects the antenna whose matching constant should be changed by comparing the reception status values of the antenna branches received from the reception status value calculation unit 16a.

  Here, variations of antenna selection performed by the selection unit 16b will be described with reference to FIG. FIG. 6 is a diagram showing variations of antenna selection. Note that (1) in the figure shows the case where antenna selection is performed based on the order of each reception situation, and (2) in the figure shows the case where antenna selection is performed using a predetermined threshold. ing. Further, A to D shown in the figure correspond to antenna A (antenna branch A) to antenna D (antenna branch D), respectively.

  As shown in (1) of FIG. 6, when performing antenna selection based on the order of reception status, the antenna branches are ranked from the one with better reception status. Then, the antenna having the worst reception status, that is, the antenna having the rank “4” is selected. For example, antenna D is selected at time T11, and antenna A is selected at time T12.

  In addition, it is good also as not selecting only the antenna with the lowest order but selecting a plurality of antennas in order with the lowest order. For example, when the antennas with ranks “3” and “4” are selected, antenna A and antenna D are selected at time T11, and antenna A and antenna D are selected at time T12.

  In addition, as shown in (2) of the figure, antenna selection can also be performed using a predetermined threshold. Here, “α” shown in the figure is a predetermined threshold value, and the reception status value is adjusted to be larger as the reception status is better. For example, at time T21, antenna A and antenna D that are below the threshold α are selected, and at time T22, antenna D is selected. Note that at time T23, there is no antenna to be selected because there is no antenna below the threshold value α.

  Although FIG. 6 shows antenna selection based on the order of reception status and antenna selection using a threshold value, antenna selection combining both may be performed. For example, it is possible to select only antennas that are below a predetermined threshold and have the lowest ranking. In this case, only the antenna D is selected at time T21 in (2) of FIG.

  6 (2) shows the case where a static threshold is used, but it depends on the traveling state of the vehicle on which the receiving device 10 is mounted, the surrounding terrain, the state of the building, or the reception state. The threshold value may be changed dynamically.

  Next, the change instruction unit 16c will be described. The change instruction unit 16c is a processing unit that instructs the matching unit 11 corresponding to the antenna selected by the selection unit 16b to change the matching constant. For example, when the antenna D is selected by the selection unit 16b, the change instruction unit 16c instructs the matching unit 11D corresponding to the antenna D to change the matching constant.

  In addition, when the change instruction unit 16c instructs to change the matching constant, for example, the change instruction unit 16c sets the direction of decreasing the capacitance of the variable capacitance diode by a predetermined change width (step), and if the reception state is improved, If it is not improved, the direction is set to the opposite direction (increase direction). By doing in this way, it is possible to always maintain the reception state of the antenna to be changed instruction target in an optimum state.

  Moreover, it is good also as providing the upper limit and lower limit of the change range of a matching constant. By setting an upper limit and a lower limit, the matching constant can be changed within the range in which the variable capacitance diode operates normally, and the capacitance of the variable capacitance diode has reached the maximum value or the minimum value. It is possible to prevent a capacity change instruction.

  The maximum ratio combining unit 17 is a processing unit that performs processing for combining the outputs of the FFTs 14 (FFTs 14A to 14D) with a maximum ratio. The error correction unit 18 is a processing unit that performs a process of correcting an error such as a bit error in the reception data subjected to the maximum ratio combining by the maximum ratio combining unit 17. Note that the reception data corrected by the error correction unit 18 is output to an external device.

  The storage unit 19 is a storage unit configured by a storage device such as an EEPROM (Electrically Erasable and Programmable Read Only Memory), and stores storage information 19a. The stored information 19a is information related to the matching constant when the power supply of the ACC power supply to the receiving device is stopped, for example, by turning off the ignition key of the vehicle on which the receiving device 10 is mounted.

  For example, the stored information 19a includes each matching constant in each matching unit 11, a selected antenna selected by the selection unit 16b in the reception state monitoring unit 16, a channel selection channel in the RF / IF 12, and the like. When the power supply of the ACC power supply to the receiving device 10 is started by turning on the ignition key of the vehicle or the like, each matching constant is read by each matching unit 11 and the selected antenna is read by the selection unit 16b. It is.

  In this way, it is possible to reproduce the reception situation when the vehicle is stopped. That is, when the ignition key of the vehicle is turned off and then turned on, the vehicle is stopped at the same place, so that the reception environment such as the direction of the vehicle and the surrounding terrain remains unchanged. Therefore, by storing the control state when the power is turned off, the reception status control when the power is turned on can be started from a good state.

  Next, a processing procedure executed by the receiving apparatus 10 will be described with reference to FIG. FIG. 7 is a flowchart illustrating a processing procedure executed by the receiving device 10. The flowchart shown in the figure is a processing procedure when the selection unit 16b performs antenna selection based on the order of reception status (see (1) in FIG. 6).

  As shown in the figure, the reception status value calculation unit 16a calculates the reception status value of each antenna branch (step S101). Then, the selection unit 16b ranks the reception status values (Step S102), and selects the antenna branch with the lowest reception status (Step S103). In step S103, a plurality of antenna branches may be selected from the one with the poor reception status.

  Subsequently, the change instructing unit 16c executes a matching constant changing process for the matching unit 11 corresponding to the antenna selected in Step S103 (Step S104), and repeats the processes after Step S101. The detailed processing procedure of the matching constant changing process is shown in FIG.

  FIG. 8 is a flowchart showing a detailed procedure of the matching constant changing process. The processing procedure shown in the figure is executed when the same antenna is continuously selected by the selection unit 16b. As shown in the figure, the previous reception status and the current reception status are compared (step S201), and if the reception status is better than the previous time (step S201, Yes), step in the same direction as the previous time (step S201). Step S202).

  Here, the same direction as the previous time indicates that when the matching constant is changed to the increasing direction in the previous time, it is set to the same increasing direction, and when the matching constant is changed to the decreasing direction last time, the same decreasing direction is set. A step means increasing or decreasing the matching constant by a predetermined step width.

  On the other hand, if the reception status is not better than the previous time (No at Step S201), the process proceeds in the opposite direction to the previous time (Step S203). Here, the direction opposite to the previous time refers to the reverse direction when the matching constant is changed to the increasing direction last time, and the increasing direction when the matching constant is changed to the decreasing direction last time.

  Subsequently, it is determined whether or not the matching constant after the step is within the changing range of the matching constant (step S204). If the matching constant is within the changing range of the matching constant (step S204, Yes), the matching after the step is performed. A change instruction is given to the matching unit 11 so as to be a constant (step S205), and the process ends.

  On the other hand, if it is not within the changing range of the matching constant (No at Step S204), the matching unit 11 is instructed to change so as to be the matching constant before the step (Step S206), and the process is terminated.

  Next, a modified example of the processing procedure executed by the receiving apparatus 10 will be described with reference to FIG. FIG. 9 is a flowchart illustrating a modification of the processing procedure executed by the receiving device 10. The flowchart shown in the figure is a processing procedure when the selection unit 16b performs antenna selection based on a predetermined threshold (see (2) in FIG. 6).

  As shown in the figure, the reception status value calculation unit 16a calculates the reception status value of each antenna branch (step S301). Then, the selection unit 16b compares each reception status value with a predetermined threshold (step S302), and selects an antenna branch that is less than the predetermined threshold (step S303). It is assumed that each reception status value is adjusted to be a larger value as the reception status is better.

  Subsequently, the change instruction unit 16c executes a matching constant changing process for the matching unit 11 corresponding to the antenna selected in Step S303 (Step S304), and repeats the processes after Step S301. The detailed procedure of the matching constant changing process has already been described with reference to FIG.

  As described above, in this embodiment, a matching unit that corresponds to each antenna and performs matching of each antenna by changing a matching constant is used, and the reception status calculation unit calculates a reception status value that represents the reception status of the antenna. Calculation is performed for each antenna system, the selection unit selects an antenna for which the matching constant is to be changed based on the calculated reception status value, and the change instruction unit matches the matching unit corresponding to the selected antenna. The receiving device was configured to instruct the change of the constant.

  Therefore, by improving the reception status of the antenna having a poor reception status and improving the reception status of the entire device, the reception status of the entire device can be maintained well even in an environment where the reception status is likely to change.

  As described above, the antenna control apparatus according to the present invention is useful when it is desired to maintain a good reception situation in frequency division combining diversity using a plurality of antennas, and the reception situation changes particularly in an automobile or the like. Suitable for easy environments.

It is a figure which shows the outline | summary of the receiving method which concerns on this invention. It is a block diagram which shows the structure of the receiver which concerns on a present Example. It is a figure which shows an example of the circuit which comprises a matching part. It is a figure which shows an example of the reference point and receiving point in a constellation. It is a figure which shows an example of reception status value calculation. It is a figure which shows the variation of antenna selection. It is a flowchart which shows the process sequence which a receiver performs. It is a flowchart which shows the detailed procedure of a matching constant change process. It is a flowchart which shows the modification of the process sequence which a receiver performs.

Explanation of symbols

10 receiver 11 matching unit 12 RF / IF
13 ADC
14 FFT
DESCRIPTION OF SYMBOLS 15 Data branch part 16 Reception condition monitoring part 16a Reception condition calculation part 16b Selection part 16c Change instruction | indication part 17 Maximum ratio synthetic | combination part 18 Error correction part 19 Memory | storage part 19a Storage information

Claims (10)

A receiving device having a plurality of antennas,
Matching means corresponding to each of the antennas and performing matching of the antennas by changing a matching constant;
Reception status value calculating means for calculating a reception status value representing the reception status of the antenna for each antenna system;
Selection means for selecting the antenna to be changed of the matching constant based on the reception status value calculated by the reception status value calculation means;
A receiving apparatus comprising: a change instructing unit that instructs the matching unit corresponding to the antenna selected by the selecting unit to change the matching constant. The selection means includes
The receiving apparatus according to claim 1, wherein a predetermined number of the antennas are selected from the ones having a poor reception status after ranking the reception status values. The selection means includes
The receiving apparatus according to claim 1 or 2, wherein the antenna whose reception status value is lower than a predetermined threshold is selected. The receiving apparatus according to claim 1, further comprising: a maximum ratio combining unit configured to combine a maximum Fourier transform output value for each antenna system with respect to all the antenna systems. The selected antenna representing the antenna selected by the selection means and the matching constant corresponding to the selected antenna are stored when the power is turned off, and the stored selected antenna and the matching constant are provided to the selection means and the matching means when the power is turned on. The receiving device according to claim 1, further comprising a storage unit configured to perform the storage. The reception status value calculating means includes
6. The reception status value is calculated based on a distance between a reference point and a reception point in a constellation in which a signal of a bit string in the antenna system is represented by an in-phase component axis and a quadrature component axis. The receiving device according to any one of the above. The change instruction means includes
When the reception condition is improved, an increase instruction or a decrease instruction is given to increase the matching constant by a predetermined step width. When the reception situation is improved, an increase instruction or a decrease instruction is given. When the reception situation deteriorates, an increase instruction is given. The receiving apparatus according to claim 1, wherein a decrease instruction is issued instead of a decrease instruction instead of a decrease instruction. The change instruction means includes
The receiving apparatus according to claim 7, wherein the increase instruction or the decrease instruction is performed within a range of a predetermined upper limit value and a predetermined lower limit value for the matching constant. The matching means includes
The receiving apparatus according to claim 1, wherein the matching constant is changed by changing the capacity of a variable diode whose capacity can be changed. The matching means includes
The receiving apparatus according to claim 1, wherein the receiving apparatus is disposed near each of the antennas.

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