JP4729539B2 - Wireless receiver - Google Patents

Description

  The present invention relates to a wireless receiver, and in particular, impedance matching between an antenna and a demodulator circuit using a matching circuit that is installed in a moving object or in the vicinity of a movable peripheral object and in which a matching constant is set. The present invention relates to a radio receiving apparatus suitable for taking

Conventionally, a technique is known in which a matching circuit is provided between an antenna and a demodulation circuit, and impedance matching is performed between the antenna and the demodulation circuit using the matching circuit (see, for example, Patent Document 1). In this technique, the matching circuit is variably controlled so that the matching constant corresponds to the combination of the selected antenna element and the reception frequency (that is, the variable matching circuit).
JP 2001-298378 A

  In order to optimize the matching constant of the matching circuit corresponding to the combination of the selected antenna element and the reception frequency as in the conventional technique described above, for example, an antenna, a variable matching circuit, and a demodulation circuit are connected. It is conceivable to adjust the matching constant by placing the entire radio receiving apparatus in an anechoic chamber so that the reception state is optimal and radiating radio waves of each reception frequency from the measuring device. However, in this adjustment method, when the matching constant is once adjusted and then the adjustment is performed again, it is necessary to optimize the reception state again in the same manner.

  In general, when the above-described wireless receiver is mounted on a moving body such as a vehicle and the antenna is particularly a glass antenna, an electric conductor such as a metal helmet is placed in front of the glass, or rain or snow falls. The environment around the antenna may change due to the attachment of glass or the temperature of the glass changing. When such a change occurs, the impedance of the antenna changes, and the matching state between the antenna and the demodulation circuit may not be the best, and optimal reception may not be possible. Therefore, with the adjustment method described above, even if such a situation occurs, it is difficult to appropriately adjust the matching constant for the reception frequency.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a wireless reception device capable of maintaining an optimal matching state between an antenna and a demodulation circuit for all reception frequencies. .

  The object is to provide impedance matching between an antenna, a demodulation circuit that demodulates a received signal received by the antenna, and the antenna and the demodulation circuit, and an output of the antenna and an input of the demodulation circuit. And a storage unit that stores a matching constant to be set in the matching circuit for each reception frequency, the matching constant stored in the storage unit for each reception frequency Reception quality detection means for detecting reception quality when the matching circuit is set, and constant adjustment for adjusting the matching constant for a reception frequency at which the reception quality detected by the reception quality detection means satisfies a predetermined quality condition Means for receiving frequency at which the reception quality does not satisfy the predetermined quality condition, The reception quality detection unit includes a constant calculation unit that calculates the matching constant by interpolation / extrapolation based on the matching constant obtained by adjusting the reception frequency by the constant adjustment unit, and the matching constant stored in the storage unit. The reception quality detected by the means is updated to the matching constant obtained by adjustment by the constant adjustment means for the reception frequency satisfying the predetermined quality condition, while the reception quality does not satisfy the predetermined quality condition The reception frequency is achieved by a wireless reception device comprising constant update means for updating to the matching constant calculated by the constant calculation means.

  In the invention of this aspect, the matching constant is adjusted for the reception frequency whose reception quality satisfies the predetermined quality condition, and the matching constant stored in the storage means is updated to the matching constant obtained by the adjustment. For reception frequencies whose reception quality does not satisfy a predetermined quality condition, matching constants are calculated by interpolation / extrapolation based on matching constants obtained by adjustment for other reception frequencies, and stored in the storage means. The constant is updated to the matching constant obtained by the calculation. According to such a configuration, even when there is a reception frequency whose reception quality does not satisfy a predetermined quality condition, an optimum matching constant is estimated by interpolation / extrapolation from the matching constants of other reception frequencies for the reception frequency. Can do. Therefore, according to the present invention, the optimum matching state can be maintained between the antenna and the demodulation circuit for all reception frequencies.

  In the wireless receiver described above, a non-volatile memory that stores a flag indicating whether or not the adjustment of the matching constant by the constant adjustment unit has been performed in the past, and adjustment of the matching constant by the constant adjustment unit, If the state of the flag stored in the non-volatile memory at power-on indicates that the matching constant adjustment by the constant adjusting means has been performed in the past, the flag And an adjustment timing control means for performing adjustment of the matching constant after the power is turned on, if the state indicates that the adjustment of the matching constant by the constant adjustment means has not been performed in the past. It can be executed automatically without any external command.

  Further, in the above-described wireless reception apparatus, if the adjustment of the matching constant by the constant adjustment unit is provided with an adjustment timing control unit that is performed when the reception quality is equal to or lower than a predetermined quality after the power is turned on, Even when an environmental change occurs later, the matching state between the antenna and the demodulation circuit can be optimized.

  Further, in the above-described wireless reception device, if the adjustment timing control unit includes a demodulation output control unit that stops the output of the demodulation circuit during the period in which the matching constant is adjusted by the constant adjustment unit, It is possible to prevent a reception signal with low reception quality from being output from the demodulation circuit.

  Further, in the above-described radio receiving apparatus, when the matching constant is adjusted by the constant adjustment means by the adjustment timing control means, the demodulation circuit immediately before the output of the demodulation circuit is stopped by the demodulation output control means. If an audio / image output control means for gradually decreasing the output audio or output image luminance based on the output of the output over time is provided, a sudden change in audio / image caused by the output stop of the demodulation circuit is avoided. be able to.

  In the radio receiving apparatus described above, the adjustment timing control means may start the adjustment of the matching constant by the constant adjustment means, and if the reception quality is equal to or higher than the predetermined quality, or the reception channel to be selected is changed. In some cases, the adjustment may be stopped.

  Further, in the above-described radio reception apparatus, the demodulation output control means may resume the output of the demodulation circuit when the adjustment of the matching constant by the constant adjustment means is completed or stopped.

  Further, in the above-described wireless reception device, the audio / image output control unit outputs the output of the demodulation circuit after restarting the output of the demodulation circuit when the adjustment of the matching constant by the constant adjustment unit is completed or stopped. If the output sound or the output image brightness based on it is gradually increased over time, it is possible to avoid a sudden change in sound and image due to the restart of the output of the demodulation circuit.

  Further, in the above-described wireless reception device, the constant adjustment unit corresponds to the reception frequency read from the storage unit for the reception frequency where the reception quality detected by the reception quality detection unit satisfies the predetermined quality condition. Control value variable means for varying a control value set in the matching circuit within a predetermined seek range determined for the matching constant, and the control value variable within the seek range by the control value variable means. The best value selecting means for selecting the best value with the best reception quality, and the best value selecting means when the control value is varied by the control value varying means for a predetermined number of times within the same seek range. Convergence determining means for determining whether or not the best value is converged, and the best value is converged by the convergence determining means A constant determining means for determining the matching constant to be stored in the storage means based on a plurality of the best values respectively selected by the best value selecting means, Thus, it is possible to obtain an optimum matching constant that provides the best reception quality.

  When the convergence determining means determines that the best value does not converge, the matching constant is not determined by the constant determining means for the reception frequency where the reception quality satisfies the predetermined quality condition, and By not updating the matching constant by the constant updating unit based on the determination, it is possible to avoid updating the matching constant stored in the storage unit based on a plurality of best values that do not converge.

  Furthermore, in the above-described radio reception apparatus, when the reception quality detected by the reception quality detection means has a predetermined interval or more between the reception frequencies satisfying the predetermined quality condition, the constant calculation means If the matching constant is not calculated for a reception frequency whose reception quality does not satisfy the predetermined quality condition, and the matching constant is not updated by the constant update means, the reception quality satisfies the predetermined quality condition. When the matching constant is not properly calculated by interpolation / extrapolation for a reception frequency that does not satisfy, it is possible to prevent the matching constant stored in the storage unit from being updated to the matching constant by the calculation.

  According to the present invention, it is possible to maintain an optimal matching state between the antenna and the demodulation circuit for all reception frequencies.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration diagram of a wireless receiver 10 according to an embodiment of the present invention. FIG. 2 is a diagram for explaining the frequency characteristics of the matching circuit included in the wireless reception device 10 of the present embodiment. FIG. 3 is a diagram showing the mounting positions of the component parts of the wireless reception device 10 of this embodiment. 3A shows the vehicle exterior view, and FIG. 3B shows the vehicle interior view. The radio receiving apparatus 10 of this embodiment is mounted on a vehicle as a moving body, and has a receiving channel selected within a predetermined frequency band of broadcasting such as TV, FM radio, and AM radio having a plurality of receiving channels. It is a device that receives a corresponding broadcast wave.

  As shown in FIG. 1, the wireless reception device 10 includes a reception antenna 12 that receives a signal of a desired broadcast wave. For example, as shown in FIGS. 3A and 3B, the receiving antenna 12 is a glass antenna installed on a vehicle glass 14 such as a rear glass or a quarter glass, and is patterned so as to receive a desired broadcast wave.

  A demodulation circuit 18 is connected to the receiving antenna 12 via a matching circuit 16 described later. The received signal received by the receiving antenna 12 is matched by the matching circuit 16 and then supplied to the demodulation circuit 18. The demodulation circuit 18 is a circuit that demodulates the reception signal received by the reception antenna 12 and matched by the matching circuit 16. Information on the currently selected reception channel is supplied to the demodulation circuit 18. The demodulation circuit 18 demodulates the reception signal corresponding to the selected reception channel. The reception signal demodulated by the demodulation circuit 18 is output to the outside as, for example, a video signal or an audio signal of TV broadcast, FM broadcast, or AM broadcast.

  The demodulation by the demodulation circuit 18 may be performed on an IF signal obtained by frequency-converting the received signal to an intermediate frequency (IF) signal, or obtained by AD converting the received signal. It may be performed on a digital signal to be generated.

  Between the reception antenna 12 and the demodulation circuit 18, a matching circuit 16 that interposes impedance matching between the output of the reception antenna 12 and the input of the demodulation circuit 18 is interposed. The matching circuit 16 is a circuit that matches reception signals received by the reception antenna 12. As shown in FIG. 3, the matching circuit 16 is disposed immediately below the receiving antenna 12, and a coaxial structure or parallel line structure is not used for connection between the antenna feeding point and the input end of the matching circuit 16. It has become. The output end of the matching circuit 16 and the input end of the demodulation circuit 18 may or may not be connected via a coaxial feeder.

  The matching circuit 16 does not have frequency characteristics (see FIG. 2A) having a relatively wide bandwidth to cover a plurality of reception channels having different frequencies within a predetermined frequency band, but within a predetermined frequency band. It has a frequency characteristic (see FIG. 2B) having a relatively narrow bandwidth enough to cover one reception channel. As shown in FIG. 1, the matching circuit 16 is formed by connecting an inductance (coil) and a capacitance (capacitor) in parallel or combining them in a T-type or π-type, and the matching constant can be varied. Yes (ie variable matching circuit).

  A control circuit 22 is connected to the matching circuit 16 via a control line 20. The control circuit 22 sets the matching constant of the matching circuit 16 by switching the circuit constant of the matching circuit 16 by supplying a switching signal through the control line 20 or by changing the voltage applied to the varactor diode, the RF-MEMS, or the like. It is a circuit for making it variable. Hereinafter, a value to be controlled when the control circuit 22 sets the matching constant of the matching circuit 16 (for example, a voltage value that drives a varactor diode, an inductance changeover switch, or the like) is referred to as a control value.

  The control circuit 22 is supplied with information on the currently selected reception channel. The control circuit 22 is connected to a non-volatile memory 24 that stores and stores table information and the like for setting matching constants for each reception frequency. As will be described later in detail, the control circuit 22 refers to the table information stored in the memory 24, specifies a matching constant corresponding to the reception frequency of the reception signal of the broadcast wave received by the reception antenna 12, and matches the matching constant. The matching circuit 16 is controlled so that the constant is realized.

  A detection circuit 26 is connected to the demodulation circuit 18. The demodulation circuit 18 outputs a signal corresponding to the reception quality (reception signal level, BER (Bit Error Rate), etc.) of the reception signal received by the reception antenna 12 to the detection circuit 26. The detection circuit 26 is a circuit that obtains the reception quality of the reception signal received by the reception antenna 12 by detecting the signal level, S / N ratio, BER and the like of the reception signal based on the signal from the demodulation circuit 18. .

  Note that the detection circuit 26 uses the reception signal demodulated by the demodulation circuit 18 as a method of detecting the reception quality of the reception signal received by the reception antenna 12, but in addition to this method, the RF reception by the matching circuit 16 is performed. By detecting the signal strength or detecting the signal strength based on the voltage value by the AGC (Automatic Gain Control) function, the reception quality of the received signal at the receiving antenna 12 is detected. Also good.

  The output of the detection circuit 26 is supplied to the control circuit 22 described above. The control circuit 22 controls the matching circuit 16 based on the reception quality of the reception signal received by the reception antenna 12 based on the information supplied from the detection circuit 26, as will be described in detail later.

  Next, with reference to FIG. 4 to FIG. 9, the operation of the wireless reception device 10 of the present embodiment will be described.

  As described above, the wireless reception device 10 of this embodiment is a device that receives broadcast waves such as FM radio, TV, and AM radio within a predetermined frequency band having a plurality of reception channels having different frequencies. 16 has a frequency characteristic having a relatively narrow bandwidth within the predetermined frequency band. For this reason, in the radio receiving apparatus 10 of the present embodiment, the reception sensitivity is improved, and characteristics such as strong input interference are improved. On the other hand, since the impedance of the receiving antenna 12 changes according to the reception frequency, in order to appropriately receive the broadcast wave of the selected desired reception channel (target frequency), the frequency of the matching circuit 16 is used. It is necessary to appropriately change the characteristics according to the target frequency of the desired reception channel.

  In particular, since the wireless reception device 10 is mounted on a vehicle that is a moving body, the reception environment is likely to change from moment to moment due to the movement of the vehicle or the movement of surrounding objects. Therefore, the frequency characteristics of the reception channel and the matching circuit 16 If the relationship remains fixed, an optimum matching constant (control value; voltage value for driving a varactor diode, an inductance changeover switch, etc.) cannot be set in the matching circuit 16 in the desired reception channel, and reception is not possible. There may be an inconvenience that good matching by the matching circuit 16 is not performed between the antenna 12 and the demodulation circuit 18.

  Therefore, after the entire radio receiving apparatus 10 connected to the receiving antenna 12, the matching circuit 16 and the demodulating circuit 18 is mounted on a vehicle and placed in an anechoic chamber so that the receiving state is the best, Even if the matching constant is adjusted by radiating radio waves of the reception frequency from the measuring device, the matching constant of the matching circuit 16 may not be optimally set when the vehicle is subsequently driven, and good matching may not be performed.

  Therefore, in the radio receiving apparatus 10 of the present embodiment, the matching constant of the matching circuit 16 is appropriately adjusted after manufacturing the vehicle on which the vehicle is mounted in order to avoid the inconvenience described above.

  FIG. 4 shows a flowchart of an example of a main routine executed by the control circuit 22 in the wireless reception device 10 of the present embodiment. FIG. 5 shows a flowchart of an example of a subroutine executed by the control circuit 22 in the normal mode in the wireless reception device 10 of the present embodiment. FIG. 6 is a flowchart illustrating an example of a subroutine executed by the control circuit 22 in the first adjustment mode in the wireless reception device 10 according to the present embodiment. FIG. 7 shows a flowchart of an example of a subroutine executed by the control circuit 22 when adjusting the matching constant in the wireless reception device 10 of the present embodiment. FIG. 8 is a diagram for explaining a method of calculating a matching constant by interpolation / extrapolation in the wireless reception device 10 according to the present embodiment. FIG. 9 shows a flowchart of an example of a subroutine executed by the control circuit 22 in the second adjustment mode in the wireless reception device 10 of the present embodiment.

  The wireless reception device 10 includes a nonvolatile memory 24, and the memory 24 stores table information for setting a matching constant for each frequency within a predetermined frequency band as described above. The information initially stored in the memory 24 may be a default value of a matching constant determined in advance theoretically and experimentally and determined to obtain the best matching state.

  In this embodiment, when the vehicle is activated with the accessory on or the ignition on and the radio receiver 10 is turned on, the control circuit 22 normally selects the target frequency selected at each time point during the power on. The matching constant corresponding to the received channel is read from the memory 24 and specified. Then, the matching constant is set in the matching circuit 16 and the matching circuit 16 is controlled so that the matching constant is realized. When the reception channel of the selected target frequency is changed, the matching constant read from the memory 24 and set in the matching circuit 16 is changed every time the reception channel is changed. Hereinafter, a mode in which the matching constant is read from the memory 24 and set in the matching circuit 16 is referred to as a normal mode.

  According to the normal mode, since the matching constant corresponding to the reception channel of the target frequency selected by the vehicle occupant is set in the matching circuit 16 during the start-up of the vehicle, the matching between the reception antenna 12 and the demodulation circuit 18 is performed. Impedance matching can be made the best and high reception quality can be ensured.

  Here, in addition to the above-described matching constant table information, the non-volatile memory 24 also includes a matching constant stored in the memory 24 at the address A1, that is, a matching constant to be set in the matching circuit 16 for each reception frequency. A flag (hereinafter referred to as “adjustment presence / absence flag”) indicating whether or not adjustment (this adjustment will be described in detail later) has been performed in the past is stored. This adjustment presence / absence flag is in an off state when the matching constant has never been adjusted in the past, and is in an on state when the matching constant has been adjusted in the past.

  When the vehicle is activated and the radio receiver 10 is powered on, the control circuit 22 first reads data about the adjustment presence / absence flag stored in the address A1 of the memory 24 (step 100), and the adjustment presence / absence flag Is determined to be in an off state indicating that the matching constant has never been adjusted (step 102).

  As a result, when a negative determination is made, that is, when the matching constant has been adjusted in the past, the normal mode is subsequently set (step 104). Specifically, in the normal mode, the control circuit 22 first detects that a specific reception channel is selected and a target frequency is set within a predetermined frequency band in accordance with a switch operation of the vehicle occupant (step 150). . When the detection is made, the matching constant corresponding to the reception channel of the set target frequency is read from the memory 24 and set in the matching circuit 16 (step 152).

  On the other hand, if an affirmative determination is made in step 102, that is, if the matching constant has not been adjusted in the past, then the matching constant is adjusted before the normal mode is performed. The mode is set (step 106). Hereinafter, the mode in which the matching constant is adjusted immediately after the power is turned on is referred to as a first adjustment mode. The first adjustment mode is a mode that assumes that the matching constant is adjusted after the vehicle is manufactured and before shipment at the factory.

  Specifically, in the first adjustment mode, the control circuit 22 first specifies and sets the lowest frequency in a predetermined frequency band having a plurality of reception channels (step 200), and the set reception frequency. A matching constant corresponding to (set frequency) is read from the memory 24 and set in the matching circuit 16 (step 202).

  Then, after the setting is performed, the reception quality of the reception signal of the broadcast wave of the set frequency received by the reception antenna 12 is obtained based on the information supplied from the detection circuit 26, and the reception quality is a predetermined quality. It is determined whether or not the condition is satisfied (step 204). The predetermined quality condition is, for example, that the reception quality (for example, reception intensity) is equal to or higher than the lowest first quality (for example, the first reception intensity) S1 at which a predetermined matching constant can be adjusted, and The maximum second quality (for example, the second received intensity) S2 that can change following the change of the control value of the matching constant set in the matching circuit 16, that is, may not be saturated may be good. In particular, when the reception quality is BER, if the received signal is received at a certain strength, the BER becomes zero, and the reception quality does not change following the change of the control value of the matching constant. It is preferable to set the predetermined quality condition with the maximum value of reception quality that changes moderately with respect to the change in the control value as the upper limit.

  As a result, if it is determined that the reception quality of the received signal of the set frequency satisfies the predetermined quality condition, then the matching constant is set as described in detail later for the set frequency at which the reception quality satisfies the predetermined quality condition. Is adjusted (step 206).

  When the control circuit 22 determines that the received quality of the received signal does not satisfy the predetermined quality condition in step 204 for the set frequency, or when the adjustment of the matching constant is completed in step 206, the control circuit 22 then sets The reception frequency to be changed is changed from the current one to the next higher one at a predetermined interval, the reception frequency after the variable is set (step 208), and the set frequency is set to the highest frequency within the predetermined frequency band. It is determined whether or not it exceeds (step 210).

  As a result, if it is determined that the set frequency does not exceed the maximum frequency, the process of step 202 is performed again, and the matching constant corresponding to the set frequency after the change is read from the memory 24 and set in the matching circuit 16. . Thereafter, the same processing is continued until the set frequency exceeds the maximum frequency.

  Here, the control circuit 22 adjusts the matching constant for the set frequency as follows (step 206). First, a matching constant corresponding to the set frequency is read from the memory 24 (step 250). Then, in order to obtain the optimum matching constant to be set in the matching circuit 16 at that time, the range of matching constants to be sought by changing the control value based on the read matching constants (hereinafter referred to as a seek range). ) Is determined (step 252).

  The seek range is determined for each reception frequency to be set, and may be limited to a part of the frequency received and used as the wireless reception device 10, and may be limited to a part of the matching circuit 16. Any device may be used as long as it is initially set based on statistical data such as component variations of elements and temperature variations, and is learned by reflecting the control values of the matching constants actually set when receiving broadcast waves. In this case, learning is performed by adjusting a seek range using threshold values such as σ and 3σ by statistically processing a plurality of control values actually set up to that point, for example. do it. Further, the seek range may be stored in advance in the memory 24 for each set frequency together with the matching constant set in the matching circuit 16, and the one corresponding to the set frequency may be read from the memory 24.

  When the control circuit 22 determines the seek range in step 252 as described above, the control circuit 22 subsequently varies the control value of the matching constant of the matching circuit 16 at predetermined value intervals within the set seek range. A process for obtaining the reception quality of each received signal is performed, and the process is performed a plurality of times.

  When the control value of the matching circuit 16 is varied within the seek range, the matching constant of the matching circuit 16 is varied according to the variation. If the reception quality of the received signal received by the receiving antenna 12 is obtained in the process in which the control value is varied within the seek range, the highest quality is obtained in the current environment among all the control values within the seek range. It becomes possible to specify the control value from which the received signal is obtained.

  Specifically, when determining the seek range in step 252 as described above, the control circuit 22 first resets the number of times of seeking within the seek range (hereinafter referred to as the number of seek completions) N to “0” ( In step 254), the first control value within the seek range is set in the matching circuit 16 as a matching constant (step 256). Then, after the setting is performed, the reception quality at the control value of the reception signal of the setting frequency received by the reception antenna 12 is obtained based on the information supplied from the detection circuit 26, and the reception quality and The relationship with the control value is temporarily stored in a temporary storage memory (or the memory 24) (step 258).

  Next, the control value of the matching constant is changed, and the changed control value is set as a matching constant in the matching circuit 16 (step 260), and it is determined whether or not the control value is within the seek range (step 260). Step 262). As a result of the determination, when the control value is within the seek range and the seek of the control value has not been completed, the process of step 258 is performed again, and the control of the received signal obtained based on the information of the detection circuit 26 is performed. The relationship between the reception quality by value and the control value is temporarily stored in the temporary storage memory. Thereafter, the same processing is continued until the control value is out of the seek range. If it is determined that the control value is out of the seek range and the seek of the control value is completed, the control value with the highest reception quality is obtained from the relationship between the reception quality obtained in one seek of the seek range and the control value. The (best value) is specified and temporarily stored in a temporary storage memory (or the memory 24) (step 264), and the seek completion count N is incremented by “1” (step 266).

  After the processing in step 266, the control circuit 22 determines whether or not the seek completion number N has reached the predetermined number N0 (step 268). Note that the predetermined number N0 is the number of times to seek to the same seek range, and is set to a predetermined number (for example, five times). In addition, it is preferable that the control value in the seek range over the predetermined number N0 is changed at predetermined time intervals in consideration of switch chattering and circuit transient response associated with the change. .

  As a result of the determination, if the number of seek completions N has not reached the predetermined number N0, the process returns to step 256 again, the first control value within the seek range is set as a matching constant in the matching circuit 16, and the subsequent processing is performed. Do.

  On the other hand, if the seek completion number N reaches the predetermined number N0, it is next determined whether or not each best value obtained by each seek has convergence (step 270). Whether or not there is convergence is determined by calculating the variance or standard deviation of the best value based on each best value obtained by varying the control value in the same seek range over a plurality of predetermined times. Therefore, it may be determined based on whether or not the variance or standard deviation is equal to or less than a predetermined threshold. When the variance or standard deviation is equal to or less than the predetermined threshold, it is determined that the best value is convergent. And it is sufficient.

  Then, when it is determined that the best value is convergent as a result of seeking in the same seek range over a predetermined number of times N0, based on each best value, the matching circuit 16 that should be used under the current environment An optimum matching constant capable of obtaining a received signal with high reception quality is calculated (step 272), and the calculated matching constant is overwritten and stored in the memory 24 in correspondence with the set frequency (step 274). A flag (measurement NG flag) stored in the memory 24 indicating whether or not an optimum matching constant at the present time with respect to the reception frequency has been measured is set to an OFF state indicating that the measurement has been performed (step 276). . After such processing is performed, if a reception channel of the reception frequency is selected, a matching constant predicted to obtain a reception signal with the highest reception quality for the reception channel is read from the memory 24. The matching circuit 16 matches the received signal from the receiving antenna 12 with the frequency characteristic according to the matching constant.

  Note that the calculation of the matching constant in step 272 is obtained by processing (for example, averaging) each best value obtained by varying the control value in the same seek range over a plurality of predetermined times using a statistical method. It is sufficient to use a different value.

  On the other hand, if it is determined that the best value is not convergent as a result of seeking in the same seek range over a predetermined number of times N0, it is assumed that multipath fading has occurred, and then the above measurement NG flag is set to the optimum value. An ON state indicating that the matching constant has not been measured is set (step 278), and it is detected that the optimum matching constant has not been obtained for the reception frequency and the matching constant has not been properly adjusted. In this case, the matching constant corresponding to the reception frequency stored in the memory 24 is maintained at the value before adjustment.

  By such a method, the control circuit 22 can adjust the matching constant for each set frequency within a predetermined frequency band, and the matching constant for each set frequency stored in the memory 24 can be adjusted by the adjustment. It is possible to make it optimal.

  In addition, the reception frequency for which the matching constant is adjusted is limited to the reception quality of the reception signal that satisfies a predetermined quality condition, and the reception frequency for which the reception quality does not satisfy the predetermined quality condition. The matching constant is not adjusted (see steps 204 and 206). That is, the matching constant stored in the memory 24 is updated to the matching constant obtained by adjustment for the reception frequency where the reception quality of the reception signal satisfies the predetermined quality condition, while the reception quality of the reception signal is predetermined. A reception frequency that does not satisfy the quality condition may not be updated as it is.

  Therefore, when the control circuit 22 determines that the set frequency exceeds the highest frequency in the predetermined frequency band in step 210 in the first adjustment mode, the reception frequency at a predetermined interval in the frequency band. Next, on the basis of the matching constant obtained by the adjustment of the reception frequency for which the matching constant is adjusted as described above when the reception quality of the received signal satisfies the predetermined quality condition, By performing interpolation / extrapolation, matching constants that are estimated to be optimal are calculated for each reception frequency in a frequency band including a reception frequency where the reception quality of the reception signal does not satisfy a predetermined quality condition (step 212).

  Specifically, for example, as shown in FIG. 8, when the frequency at which the matching constant is obtained by adjustment is x0 to xi (i = 3 in the figure) and the matching constant at these frequencies is y0 to yi, the adjustment is performed. The matching constant ya at the frequency xa that has not been performed is obtained according to the following equation (1) using a Lacrangian interpolation polynomial. Note that the matching constant may be calculated by interpolation / extrapolation by a method other than a method using a Lagrange interpolation polynomial.

制御回路２２は、上記の如く受信信号の受信品質が所定の品質条件を満たさない受信周波数を含む周波数バンド内の各受信周波数についてマッチング定数を算出すると、その算出したマッチング定数を周波数に対応させてメモリ２４に上書きして格納する（ステップ２１２）。

When the control circuit 22 calculates the matching constant for each reception frequency in the frequency band including the reception frequency where the reception quality of the reception signal does not satisfy the predetermined quality condition as described above, the control circuit 22 associates the calculated matching constant with the frequency. The memory 24 is overwritten and stored (step 212).

  Note that the measurement NG flag is in the ON state because the best value does not converge even at the reception frequency in which the matching constant is adjusted as described above when the reception quality of the reception signal satisfies the predetermined quality condition. Since it can be determined that the optimum matching constant has not been obtained by the adjustment, the matching constant for the received frequency is the same as the matching constant for the received frequency where the received quality of the received signal does not satisfy the predetermined quality condition. It is good also as calculating with the method of and storing in the memory 24.

  When the control circuit 22 completes the process of step 212, it assumes that the adjustment of the matching constant in the first adjustment mode has been completed, and sets the adjustment presence / absence flag to the on state and writes it to the address A1 of the memory 24 (step 108). Then, the mode is shifted from the first adjustment mode to the normal mode (step 104).

  As described above, in the wireless receiving device 10 according to the present embodiment, immediately after the power is turned on when the vehicle is started, when the matching constant has not been adjusted for each reception frequency in the frequency band in the past, the first adjustment is performed. In this mode, the memory 24 can be updated by adjusting the matching constant of each reception frequency. On the other hand, when the matching constant has been adjusted for each reception frequency in the frequency band in the past, the normal mode is immediately entered, and the matching constant corresponding to the reception channel of the selected target frequency is stored from the memory 24. By reading out, the matching circuit 16 can be set to a frequency characteristic according to the matching constant, and the output of the receiving antenna 12 and the input of the demodulation circuit 18 can be impedance-matched.

  In this regard, according to the present embodiment, the matching constant can be adjusted in the first adjustment mode unless the matching constant has been adjusted in the past after the power is turned on when the vehicle is started. Constant adjustment can be automatically executed without any external command including operation by the operator, and the labor of the operator for adjusting the matching constant can be reduced in the factory before shipment after vehicle manufacture. It can be omitted. In the present embodiment, the adjustment of the matching constant described above is performed by actually receiving the broadcast wave transmitted from each broadcasting station. Therefore, the same frequency as the frequency of the broadcast wave is intentionally generated and the matching is performed. It is possible to calculate an optimum matching constant without adjusting the constant and without using expensive equipment such as an anechoic chamber for the adjustment.

  In the present embodiment, when the control circuit 22 enters the normal mode in step 104 described above, the control circuit 22 is thereafter received by the receiving antenna 12 based on the information supplied from the detection circuit 26 every predetermined time T1 in the normal mode. The reception quality of the broadcast wave reception signal of the reception channel of the target frequency selected at that time is checked (step 110). As a result of the check, the reception quality is equal to or lower than a predetermined third quality S3. Whether or not (step 112). The third quality S3 is the highest quality at which it is possible to determine that audio and video broadcast output is not appropriately performed, and is set in advance to a value lower than the first quality S1.

  If the reception quality exceeds the third quality S3 as a result of the above determination, the process of step 104 described above is performed. On the other hand, if the reception quality is equal to or lower than the third quality S3, the next selected object is selected. It is determined whether or not a change in frequency (reception channel) is instructed by the operation of the vehicle occupant (step 114). As a result of the determination, if there is an instruction to change the target frequency, the above-described processing of step 104 is performed again. On the other hand, if there is no instruction to change the target frequency, the mode for adjusting the matching constant from the normal mode is performed next. (Step 116).

  Hereinafter, a mode in which the normal mode is shifted to adjust the matching constant is referred to as a second adjustment mode. Note that the second adjustment mode is a mode that assumes that the matching constant is adjusted during traveling after vehicle shipment. The transition from the normal mode to the second adjustment mode may be performed when the reception quality is the third quality S3 or less once, but the reception quality is the third quality S3 or less. It may be performed when a predetermined number of times occurs.

  Specifically, in the second adjustment mode, the control circuit 22 first instructs the demodulation circuit 18 to stop the demodulation output (step 300). Then, the target frequency Fn selected as the reception channel at that time is temporarily stored in a temporary storage memory (or the memory 24) (step 302). When a command is given to the demodulating circuit 18 described above, the demodulating circuit 18 stops demodulating output, so that audio output and video output based on the received signal to the outside are not performed.

  The control circuit 22 stores a flag (adjustment incomplete flag) indicating whether or not the adjustment of the matching constant in the second adjustment mode, which is stored in the memory 24 after the processing of the above step 302, is started while being stopped halfway. Is in an on state indicating incomplete (step 304). As a result, when the adjustment incompletion flag is in an off state that does not indicate incompletion (that is, the first adjustment mode is entered for the first time and the second adjustment mode has been entered so far, but within a predetermined frequency band) If the adjustment of the matching constants for all reception frequencies is completed), the lowest frequency within a predetermined frequency band having a plurality of reception channels is specified and set in the same manner as in the process of step 200 above. (Step 306).

  Similar to the process in step 202, the matching constant corresponding to the set reception frequency (set frequency) is read from the memory 24 and set in the matching circuit 16 (step 308). Thereafter, it is determined whether or not the reception quality of the reception signal of the broadcast wave of the set frequency received by the receiving antenna 12 that is obtained based on the information supplied from the detection circuit 26 satisfies a predetermined quality condition (step) 310) If the reception quality of the received signal for the set frequency is determined to satisfy a predetermined quality condition as in the process of step 206, the reception quality satisfies the predetermined quality condition next. For the set frequency, the matching constant is adjusted according to the routine shown in FIG. 7 (step 312).

  If the control circuit 22 determines that the received quality of the received signal does not satisfy the predetermined quality condition in step 310 for the set frequency, or if the adjustment of the matching constant is completed in step 312, then the control circuit 22 In step 302, the target frequency Fn stored in the temporary storage memory is set (step 314), and the set frequency is changed to the target frequency Fn.

  Then, it is determined whether or not the reception quality of the reception signal of the broadcast wave of the reception channel of the target frequency Fn received by the reception antenna 12 is still maintained below the third quality S3 (step 316). If the quality is equal to or lower than the third quality S3, it is next determined whether or not the change of the selected target frequency (reception channel) is instructed by the operation of the vehicle occupant (step 318).

  If there is no instruction to change the target frequency as a result of the determination, the reception frequency to be set is changed from the current one to the next higher one at a predetermined interval, and the variable reception frequency is set (step) 320). It should be noted that the setting frequency in the second adjustment mode may be changed at a larger interval than the setting frequency in the first adjustment mode. According to such a configuration, the setting frequency in the second adjustment mode is changed. The adjustment of the matching constant of each reception frequency within a predetermined frequency band can be completed more quickly than the adjustment in the first adjustment mode.

  When the reception frequency is set in step 320, the control circuit 22 determines whether or not the set frequency exceeds the highest frequency in a predetermined frequency band, similarly to the process in step 210 described above (step 322). ). As a result, if it is determined that the set frequency does not exceed the maximum frequency, the process of step 308 is performed again, and the matching constant corresponding to the set frequency after the variable is read from the memory 24 and set in the matching circuit 16. . Thereafter, the same processing is continued until the set frequency exceeds the maximum frequency.

  On the other hand, in the second adjustment mode, if it is determined that the set frequency exceeds the maximum frequency, it is determined that the setting of the reception frequency at the predetermined interval in the frequency band is completed, Similar to the processing, interpolation / extrapolation is performed on the reception frequency whose matching constant is adjusted as described above when the reception quality of the received signal satisfies a predetermined quality condition, based on the matching constant obtained by the adjustment. By calculating the matching constant estimated to be optimal for each reception frequency in the frequency band including the reception frequency where the reception quality of the received signal does not satisfy the predetermined quality condition, the calculated matching constant is associated with the frequency. The data is overwritten and stored in the memory 24 (step 324).

  When the processing of step 324 is performed, the adjustment of the matching constant in the second adjustment mode is completed. Next, the adjustment incomplete flag is set to an off state that does not indicate incompletion (step 326), and the demodulation circuit 18 is set. A command is then issued to resume demodulation output (step 328). In this case, when the demodulation circuit 18 resumes the demodulation output, normal audio output and video output based on the externally received signal are resumed.

  The control circuit 22 determines that the reception quality of the broadcast wave reception signal of the reception channel of the target frequency Fn received by the reception antenna 12 in the above step 316 exceeds the third quality S3, and the above step. If it is determined in 318 that there is an instruction to change the target frequency, the adjustment of the matching constant in the second adjustment mode is stopped, and thereafter, the set frequency set at that time is stored in the memory 24 as the adjustment resumption frequency Fa. In addition, the adjustment incomplete flag of the memory 24 is set to an ON state indicating incomplete (step 330), and a command to restart the demodulation output is issued to the demodulation circuit 18 (step 328).

  When the control circuit 22 completes the processing of step 328, the adjustment of the matching constant in the second adjustment mode is completed or stopped. Next, the start of the vehicle is stopped by turning off the accessory or turning off the ignition, and the wireless reception device. It is determined whether or not the power-off of 10 is instructed by the operation of the vehicle occupant (step 118). As a result of the determination, if there is no instruction to turn off the power, the above-described processing in step 104 is performed again to return to the normal mode. On the other hand, if there is an instruction to turn off the power, all the processes are ended.

  When the adjustment of the matching constant in the second adjustment mode is stopped, the control circuit 22 stores the adjustment restart frequency Fa in the memory 24 and stores the adjustment incomplete flag in the ON state in the memory 24. When the second adjustment mode is started again, an affirmative determination is made in step 304 above, and then the adjustment restart frequency Fa stored in the memory 24 within a predetermined frequency band is read and set (step 332). Then, the processing after step 308 is executed.

  As described above, in the radio receiving apparatus 10 of the present embodiment, in the normal mode, the reception quality of the reception signal of the broadcast wave of the reception channel of the selected target frequency received by the reception antenna 12 exceeds the third quality S3. If so, the normal mode can be continued without updating the relationship between the reception frequency stored in the memory 24 and the matching constant. On the other hand, when the reception quality is lowered to the third quality S3 or lower, the second adjustment mode is entered, and the matching constant of each reception frequency can be adjusted to update the memory 24.

  In this regard, according to the wireless receiver 10 of the present embodiment, the matching circuit 16 has a frequency characteristic having a relatively narrow bandwidth as described above, but has such a relatively narrow frequency characteristic. The matching circuit 16 can also select an optimal matching constant according to the radio wave reception environment in the normal mode after adjusting the matching constant in the second adjustment mode. Even in a situation where the radio wave reception environment may change due to the movement of the vehicle to be mounted or the movement of the antenna surroundings, the frequency characteristics of the matching circuit 16 are maintained in a relatively narrow band, that is, the noise amount is reduced and the reception sensitivity It is possible to optimize the matching state between the receiving antenna 12 and the demodulation circuit 18 with better reception quality while ensuring the improvement effect. It has become.

  In addition, in the wireless reception device 10 of the present embodiment, the demodulation output of the demodulation circuit 18 is stopped during the period in which the matching constant is adjusted in the second adjustment mode due to the decrease in reception quality in the normal mode. For this reason, it is possible to prevent a reception signal with low reception quality from being output from the demodulation circuit 18. In addition, a reception signal having a frequency different from the target frequency selected by the operation of the vehicle occupant is received by the reception antenna 12 due to the change of the set frequency within the predetermined frequency band in the second adjustment mode. Since the demodulated output based on the received signal is avoided from being output from the demodulator circuit 18 as an audio output / video output, it is possible to prevent the output of audio and video of a reception channel different from the desired reception channel. Is possible.

  Further, in the wireless receiver 10 of the present embodiment, after the adjustment of the matching constant in the second adjustment mode is completed or stopped, the demodulation output of the demodulation circuit 18 is stopped and the demodulation output is resumed. . For this reason, in the normal mode after the demodulation output of the demodulation circuit 18 is resumed, it is possible to appropriately output audio and video of the desired reception channel.

  Further, in the radio receiving apparatus 10 according to the present embodiment, even when the adjustment of the matching constant in the second adjustment mode is started due to a decrease in the reception quality of the received signal with respect to the target frequency in the normal mode, When the reception quality of the received signal is recovered or when the target frequency is changed to another frequency, the adjustment of the matching constant in the second adjustment mode is stopped. If the reception quality of the received signal for the target frequency is restored, it is not necessary to adjust the matching constant to improve the reception quality. If the target frequency is changed to another frequency, the received signal for the target frequency is not changed. Therefore, it may be unnecessary to adjust the matching constant in order to improve the reception quality. Therefore, according to the present embodiment, it is possible to prevent the matching constant adjustment in the second adjustment mode from being continuously performed unnecessarily.

  Here, since the second adjustment mode is a mode assumed when the vehicle is traveling, the second adjustment mode takes a long time from the demodulation circuit 18 based on the received signal of the target frequency selected during the traveling. This is not preferable because the output is limited.

  On the other hand, in the radio receiving apparatus 10 according to the present embodiment, the setting frequency in the second adjustment mode is changed at a frequency interval larger than the setting frequency in the first adjustment mode. For this reason, according to the configuration of the present embodiment, the adjustment of the matching constant of each reception frequency within the predetermined frequency band in the second adjustment mode is completed more quickly than the adjustment in the first adjustment mode. It is possible to prevent the second adjustment mode from extending for a longer time than the first adjustment mode, and it is possible to reduce the processing load associated with the adjustment of the matching constant in the second adjustment mode.

  Furthermore, in the radio receiving apparatus 10 of the present embodiment, after the adjustment of the matching constant in the second adjustment mode is temporarily stopped as described above, the reception quality of the received signal for the target frequency in the normal mode decreases. Again, the mode is shifted from the normal mode to the second adjustment mode, and the matching constant is adjusted in the second adjustment mode. In this case, the adjustment of the matching constant in the second adjustment mode to be executed this time is The adjustment is performed in order from the adjustment resumption frequency Fa at which the adjustment was stopped in the previous second adjustment mode, not from the lowest frequency in the frequency band.

  For this reason, according to the configuration of the present embodiment described above, the frequency band that is the target of adjusting the matching constant in the second adjustment mode again after the adjustment of the matching constant in the second adjustment mode is temporarily stopped in the middle. The number of set frequencies can be reduced as compared with the normal number, so that the adjustment of the matching constant in the second adjustment mode can be completed as quickly as possible. It is possible to prevent a longer time than in the second adjustment mode, and it is possible to reduce the processing load accompanying the adjustment of the matching constant in the second adjustment mode.

  By the way, in the wireless receiver 10 of the present embodiment, the matching constant adjustment in the first adjustment mode and the second adjustment mode described above is performed by reading the matching constant corresponding to the set frequency from the memory 24 and focusing on the matching constant. A seek range is set, and a control value of a matching constant set in the matching circuit 16 is varied at predetermined value intervals within the seek range. Then, the reception quality of the received signal for each control value is obtained in the process of changing the control value (seek), and the control value (best value) that provides the best reception quality by the peak search among all the control values is obtained. Select and determine whether or not multiple best values obtained by seeking over a predetermined number of times N0 within the same seek range have convergence, and if there is convergence, statistically best reception from those best values Determine matching constants that are expected to yield quality.

  Therefore, according to the matching constant adjusting method of this embodiment, the matching constant for each reception frequency to be set in the matching circuit 16 is adjusted to a matching constant that is predicted to obtain a reception signal with the best reception quality. In the normal mode after the adjustment, the matching circuit 16 is set to a frequency characteristic in accordance with an optimum matching constant for the selected reception channel, whereby the output of the reception antenna 12 and the input of the demodulation circuit 18 are set. Can be impedance-matched in an optimum state.

  Furthermore, in the radio receiving apparatus 10 of the present embodiment, the adjustment of the matching constant in the first adjustment mode and the second adjustment mode described above is performed only for the reception frequency where the reception quality of the received signal satisfies the predetermined quality condition, and the memory Among the matching constants stored in 24, the matching constant corresponding to the reception frequency is updated to the matching constant obtained as a result of the adjustment. That is, the adjustment of the matching constant described above is not performed for a reception frequency where the reception quality of the received signal does not satisfy a predetermined quality condition, but the matching constant corresponding to the reception frequency is adjusted for the other reception frequencies. Is calculated by interpolation / extrapolation based on the matching constant obtained as a result of the above and stored in the memory 24.

  In this regard, in the present embodiment, the matching constant stored in the memory 24 can be updated to the one obtained by the above adjustment for the reception frequency where the reception quality of the reception signal satisfies the predetermined quality condition. The reception frequency at which the reception quality of the received signal does not satisfy the predetermined quality condition can be updated to one calculated by interpolation / extrapolation based on the one obtained by the above adjustment. According to such a configuration, even if there is a reception frequency where the reception quality does not satisfy the predetermined quality condition and the above-described matching constant is not adjusted, the matching constant for the reception frequency is changed to the reception quality is the predetermined quality condition. Other reception frequencies satisfying the condition can be estimated by interpolation / extrapolation from matching constants obtained by adjustment.

  Therefore, according to the radio receiving apparatus 10 of the present embodiment, even when there is a reception frequency where the reception quality does not satisfy the predetermined quality condition and the matching constant is not adjusted, the matching constant for the reception frequency is present. Can be prevented from being updated at the time of the adjustment mode, so that the receiving antenna 12 and the demodulation circuit 18 are optimally matched between the reception antenna 12 and the demodulation circuit 18 at the time of the normal mode for all reception frequencies within a predetermined frequency band. It is possible to keep.

  Here, in the radio receiving apparatus 10 of the present embodiment, even if the matching constant adjustment in the first adjustment mode and the second adjustment mode described above is performed for the reception frequency where the reception quality satisfies a predetermined quality condition, the seek range is reached. If the best value with the best reception quality is not converged, the matching constant is not measured for the received frequency, and the matching constant stored in the memory 24 is not updated and is not adjusted. Maintained. For this reason, it is possible to avoid that a matching constant that is not very appropriate is measured and stored and updated in the memory 24 based on a plurality of best values that do not converge for a reception frequency whose reception quality satisfies a predetermined quality condition. It has become.

  If the best value does not converge and the matching constant is not measured for the reception frequency where the reception quality satisfies the predetermined quality condition, the matching constant is set for the reception frequency whose reception quality does not satisfy the predetermined quality condition. Similarly to the matching constant, it may be calculated by interpolation / extrapolation based on the matching constant obtained as a result of the above adjustment for other reception frequencies, and may be stored in the memory 24. According to such a configuration, it is possible to prevent a situation in which the matching constant for the reception frequency at which the best value does not converge in the adjustment mode despite the reception quality satisfying the predetermined quality condition is not updated at all in the adjustment mode. This makes it possible to maintain an optimal matching state between the receiving antenna 12 and the demodulating circuit 18 in the normal mode for all reception frequencies within a predetermined frequency band.

  In the above embodiment, the memory 24 is stored in the “storage means” described in the claims, and the address A1 of the memory 24 storing the adjustment presence / absence flag is stored in the “nonvolatile memory” described in the claims. , Respectively. Further, the detection circuit 26 detects the reception quality of the reception signal received by the reception antenna 12 based on the information supplied from the demodulation circuit 18 for each reception frequency. The control means 22 executes the process of step 206 in the routine shown in FIG. 6 and the process of step 312 in the routine shown in FIG. By executing the process of step 212 and the process of step 324, the “constant calculation means” described in the claims can be changed to the process of step 212, the process of step 274 in the routine shown in FIG. By executing the processing, the “constant updating means” described in the claims is executed by steps 100 and 102 in the routine shown in FIG. The “adjustment timing control means” described in claim 2 of the present invention by executing the processes of steps 110, 112 and 114 performs the processes of steps 110, 112 and 114. The “adjustment timing control means” described in (2) executes the processing of steps 300 and 328 in the routine shown in FIG. 9, thereby realizing the “demodulation output control means” described in the claims.

  Further, when the control circuit 22 executes the processing of steps 252 to 256, 260, and 262 in the routine shown in FIG. 7, the “control value varying means” described in the claims executes the processing of step 264. By doing so, the “best value selection means” described in the claims executes the processing of step 270, and the “convergence determination means” described in the claims executes the processing of step 272. The “constant determining means” described in the claims is realized.

  By the way, in the above embodiment, when the condition for shifting to the second adjustment mode in the normal mode is satisfied, the demodulation output of the demodulation circuit 18 is stopped immediately after the mode shifts from the normal mode to the second adjustment mode. Thus, when the adjustment of the matching constant in the second adjustment mode is started, the demodulated output of the demodulator circuit 18 is not immediately stopped, but the output sound or output image luminance based on the demodulated output immediately before the demodulated output is stopped. May be gradually reduced over time, and the output of the demodulated output may be stopped after the output audio or output image luminance is reduced below a predetermined level. According to such a modification, it is possible to reliably avoid a sudden output change in sound or image due to the output of the demodulation circuit 18 being stopped when the execution of the second adjustment mode is started. In this case, after the control circuit 22 establishes the matching constant adjustment start condition in the second adjustment mode and before the output stop command of the demodulation circuit 18 is issued, the control circuit 22 sets the output audio and output image brightness based on the demodulated output over time. As a result, the "audio / image output control means" described in the claims is realized.

  On the contrary, when the condition for ending the second adjustment mode (one of the completion condition and the stop condition for the adjustment of the matching constant in the second adjustment mode) is satisfied, the demodulation output of the demodulation circuit 18 is resumed and resumed as usual. The audio output or the video output is resumed with the sound and the brightness of the image, but immediately after the restart, the output is not limited to the normal sound and the brightness, but the output sound and the output image brightness based on the demodulated output after the demodulation output of the demodulation circuit 18 is resumed. May be gradually increased over time. According to such a modification, it is possible to reliably avoid a sudden increase in the output of sound and images due to the restart of the output of the demodulation circuit 18 when shifting from the second adjustment mode to the normal mode. In this case, the control circuit 22 gradually sets the output sound and the output image luminance based on the demodulated output over time after the output of the demodulating circuit 18 is resumed after the matching constant adjustment end condition in the second adjustment mode is satisfied. By increasing the size, the “audio / image output control means” described in the claims can be realized.

  Further, in the above embodiment, in the first adjustment mode or the second adjustment mode, the matching constant for the reception frequency where the reception quality of the reception signal does not satisfy the predetermined quality condition is set, and the reception quality of the reception signal is predetermined. The reception frequency satisfying the quality condition is calculated by interpolation / extrapolation based on the matching constant obtained by the adjustment by the routine shown in FIG. 7, stored in the memory 24 and updated. However, while there are a plurality of reception frequencies where the reception quality of the reception signal satisfies a predetermined quality condition and the matching constant is obtained by the adjustment by the routine shown in FIG. 7, the interval between these reception frequencies is equal to or greater than the predetermined interval. In other words, if there is a case where the interval between adjacent reception frequencies is equal to or greater than a predetermined interval, the control circuit 22 that detects this does not satisfy the predetermined quality condition of the reception quality of the received signal The received frequency may not be calculated by interpolation / extrapolation of the matching constant, and the matching constant stored in the memory 24 may not be updated.

  If there is something that is over a predetermined interval between adjacent reception frequencies, there is a possibility that interpolation / extrapolation may not be performed accurately, but according to the above modification, When a matching constant is not properly calculated by interpolation / extrapolation for a reception frequency whose reception quality does not satisfy a predetermined quality condition, the matching constant stored in the memory 24 is based on the calculation by interpolation / extrapolation. The update to the matching constant can be avoided, so that the reception antenna 12 and the demodulation circuit 18 are not kept in an optimal matching state for the reception frequency whose reception quality does not satisfy the predetermined quality condition. Can be prevented.

  In this case, the control circuit 22 may not be able to accurately perform interpolation / extrapolation by an operator or the like in the first adjustment mode assuming that the matching constant is adjusted before shipment from the factory. The information may be output to the outside in order to notify the user. According to such a modification, in the first adjustment mode, it is possible to warn an operator or the like that there is a possibility that interpolation / extrapolation of the matching constant may not be performed accurately.

  In the above embodiment, the matching constant is adjusted in the matching circuit 16 in the second adjustment mode when the selected reception channel is changed and the reception quality of the reception signal received by the reception antenna 12 is significantly deteriorated. However, the trigger condition for starting automatic matching is not limited to this, and the adjustment may be performed when a temperature change of a predetermined value or more occurs. According to such a configuration, since the matching constant that provides the best reception quality corresponding to the temperature change is measured, it is possible to perform the optimum automatic matching that quickly follows the temperature change.

  Alternatively, the matching constant may be adjusted periodically in the second adjustment mode in the matching circuit 16 every time a predetermined time elapses. Further, in this modified example, when the temperature change more than a predetermined value occurs or immediately after the start of the engine of the vehicle in which the temperature change around the wireless receiver 10 becomes significant, the predetermined time is shortened, that is, the second adjustment mode. It is good also as shortening the period which performs adjustment of the matching constant by. According to such a configuration, when the temperature change of the wireless reception device 10 becomes significant, it is possible to quickly adjust the matching constant in the second adjustment mode and optimize the matching by the matching circuit 16.

  In the above-described embodiment, the seek range for each reception channel is uniform regardless of the temperature around the matching circuit 16, but the seek range may be changed according to the ambient temperature. According to such a configuration, matching by the matching circuit 16 can be made appropriate following the temperature change of the wireless reception device 10.

  In the above-described embodiment, the reception frequency in the predetermined frequency band in the first adjustment mode or the second adjustment mode is uniformly changed regardless of the reception area. The received frequency may be made different depending on the receiving area (for example, the broadcasting target area such as Tokai region or Kanto region). According to such a modification, the reception frequency for adjusting the matching constant is defined in advance corresponding to the area, the area where the vehicle is located is detected by a navigation device, and the reception frequency for adjusting the matching constant is set as the reception area. Therefore, the time required for adjusting the matching constant in the first adjustment mode or the second adjustment mode can be shortened, and the adjustment can be performed efficiently.

  In the above-described embodiment, the matching constant may be adjusted in the second adjustment mode during traveling after the vehicle is shipped. However, only two modes, the normal mode and the first adjustment mode, are used. The matching constant may not be adjusted in the adjustment mode.

  Further, in the above embodiment, when the wireless receiver 10 is turned on, if the state of the adjustment presence / absence flag stored in the address A1 of the memory 24 is OFF, the first adjustment mode is set, and the adjustment presence / absence flag is set. When the state is the on state, the normal mode is set. However, after the power is turned on, the normal mode (step 400 shown in FIG. 10 and FIG. 6) is generally used, but the selected target frequency (reception channel) is changed. It is detected that a predetermined external operation (for example, a short-circuit operation between predetermined terminals) has been performed or a predetermined external signal is supplied without being instructed by the operation of the vehicle occupant (when a negative determination is made in step 402) Is detected (at the time of an affirmative determination in step 404), the first adjustment mode (step 406 and FIG. 6) is entered, and there is an instruction to turn off the power. (Until a positive determination in step 408), it is also possible to continue the first adjustment mode.

  In the above embodiment, the demodulating circuit 18 demodulates the received signal matched by the matching circuit 16. However, when the demodulating process of the demodulating circuit 18 digitally processes the received signal. An AD converter may be interposed between the matching circuit 16 and the demodulation circuit 18. Even with this configuration, it is possible to obtain the same effect as the configuration of the above-described embodiment.

  In the above embodiment, the wireless receiver 10 is mounted on a vehicle. However, the present invention is not limited to this, and a railway train or a user whose radio wave reception environment can change as a moving body. It may be installed in a portable device that is carried by a mobile phone, or it may be installed not only on a moving body such as a vehicle or a portable device, but also on a fixed object whose radio wave reception environment can be changed by the movement of surrounding objects. Good.

  Furthermore, in the above embodiment, the radio receiver 10 receives broadcast waves such as FM radio, AM radio, and TV. However, the present invention is not limited to this, and the vehicle and the vehicle user. It is good also as what receives the communication electromagnetic wave (For example, the electromagnetic wave utilized for a keyless entry system or a tire pressure detection system) between the portable apparatuses which carry.

It is a block diagram of the radio | wireless receiving apparatus which is one Example of this invention. It is a figure for demonstrating the frequency characteristic of the matching circuit with which the radio | wireless receiver of a present Example is provided. It is the figure showing the mounting position of the component of the radio | wireless receiver of a present Example. It is a flowchart of an example of the main routine performed in the radio | wireless receiver of a present Example. 6 is a flowchart of an example of a subroutine executed in a normal mode in the wireless reception device of the present embodiment. It is a flowchart of an example of the subroutine performed at the time of the 1st adjustment mode in the radio | wireless receiver of a present Example. It is a flowchart of an example of the subroutine performed at the time of adjustment of a matching constant in the radio | wireless receiver of a present Example. It is a figure for demonstrating the method of calculating a matching constant by the interpolation and extrapolation in the radio | wireless receiver of a present Example. It is a flowchart of an example of the subroutine performed at the time of the 2nd adjustment mode in the radio | wireless receiver of a present Example. It is a flowchart of an example of the control routine performed in the radio | wireless receiver which is a modification of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radio receiver 12 Reception antenna 16 Matching circuit 18 Demodulation circuit 22 Control circuit 24 Memory 26 Detection circuit

Claims (11)

An antenna, a demodulation circuit that demodulates a reception signal received by the antenna, and a matching circuit that is interposed between the antenna and the demodulation circuit and that performs impedance matching between the output of the antenna and the input of the demodulation circuit; A storage unit that stores a matching constant to be set in the matching circuit for each reception frequency,
Reception quality detecting means for detecting reception quality when the matching constant stored in the storage means is set in the matching circuit for each reception frequency;
Constant adjustment means for adjusting the matching constant for a reception frequency at which the reception quality detected by the reception quality detection means satisfies a predetermined quality condition;
Constant calculation for calculating the matching constant by interpolation / extrapolation based on the matching constant obtained by adjustment by the constant adjusting unit for other reception frequencies for the reception frequency where the reception quality does not satisfy the predetermined quality condition Means,
The matching constant stored in the storage means is updated to the matching constant obtained by adjustment by the constant adjustment means for a reception frequency at which the reception quality detected by the reception quality detection means satisfies the predetermined quality condition. On the other hand, constant update means for updating the matching constant calculated by the constant calculation means for a reception frequency where the reception quality does not satisfy the predetermined quality condition;
A radio receiving apparatus comprising: A non-volatile memory for storing a flag indicating whether or not the adjustment of the matching constant by the constant adjusting unit has been performed in the past;
The adjustment of the matching constant by the constant adjusting means indicates that the state of the flag stored in the non-volatile memory at power-on indicates that the matching constant has been adjusted by the constant adjusting means in the past. On the other hand, if the flag state indicates that the adjustment of the matching constant by the constant adjustment unit has not been performed in the past, the adjustment timing control unit is performed.
The wireless receiver according to claim 1, comprising:   2. The radio reception apparatus according to claim 1, further comprising an adjustment timing control unit that adjusts the matching constant by the constant adjustment unit when the reception quality is equal to or lower than a predetermined quality after power is turned on.   4. The radio receiving apparatus according to claim 3, further comprising demodulation output control means for stopping output of the demodulation circuit during a period in which the adjustment constant control means adjusts the matching constant by the constant adjustment means.   When adjustment of the matching constant is performed by the constant adjustment unit by the adjustment timing control unit, an output sound or output image based on the output of the demodulation circuit immediately before the output of the demodulation circuit is stopped by the demodulation output control unit 5. The radio receiving apparatus according to claim 4, further comprising sound / image output control means for gradually decreasing the luminance over time.   The adjustment timing control unit, after starting the adjustment of the matching constant by the constant adjustment unit, stops the adjustment when the reception quality is equal to or higher than the predetermined quality or when there is a change in a reception channel to be selected. The wireless receiving device according to claim 3, wherein the wireless receiving device is a wireless receiver.   5. The radio receiving apparatus according to claim 4, wherein the demodulation output control means restarts the output of the demodulation circuit when the adjustment of the matching constant by the constant adjustment means is completed or stopped.   When the adjustment of the matching constant by the constant adjustment unit is completed or stopped, the audio / image output control unit calculates the output audio or the output image luminance based on the output of the demodulation circuit after the restart of the output of the demodulation circuit. 6. The radio reception apparatus according to claim 5, wherein the radio reception apparatus is gradually increased over time. The constant adjusting means is
The reception quality detected by the reception quality detection means is within a predetermined seek range determined for the matching constant corresponding to the reception frequency read from the storage means for the reception frequency satisfying the predetermined quality condition. Control value varying means for varying the control value set in the matching circuit;
Best value selection means for selecting the best value of the reception quality from among the control values that are varied within the seek range by the control value variable means;
Convergence determining means for determining whether or not the best value selected by the best value selecting means converges when the control value is varied by the control value varying means a predetermined number of times in the same seek range; ,
Constant determination for determining the matching constant to be stored in the storage unit based on the plurality of best values respectively selected by the best value selection unit when the convergence determination unit determines that the best value is converged Means,
The wireless reception device according to claim 1, further comprising:   When the convergence determining means determines that the best value does not converge, the matching constant is not determined by the constant determining means for the reception frequency where the reception quality satisfies the predetermined quality condition. The wireless receiving apparatus according to claim 9, wherein the matching constant is not updated by the constant updating unit based on. When the reception quality detected by the reception quality detection means has a predetermined interval or more between the reception frequencies satisfying the predetermined quality condition, the reception quality by the constant calculation means satisfies the predetermined quality condition. 11. The radio reception apparatus according to claim 1, wherein the matching constant is not calculated for a reception frequency that does not satisfy, and the matching constant is not updated by the constant updating unit.

Images