WO2014115388A1 - 受信装置および受信装置の制御方法 - Google Patents
受信装置および受信装置の制御方法 Download PDFInfo
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- WO2014115388A1 WO2014115388A1 PCT/JP2013/078843 JP2013078843W WO2014115388A1 WO 2014115388 A1 WO2014115388 A1 WO 2014115388A1 JP 2013078843 W JP2013078843 W JP 2013078843W WO 2014115388 A1 WO2014115388 A1 WO 2014115388A1
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- 238000000034 method Methods 0.000 title claims abstract description 18
- 230000005236 sound signal Effects 0.000 claims description 28
- 230000006870 function Effects 0.000 abstract description 8
- 230000008569 process Effects 0.000 description 11
- 230000008859 change Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000005684 electric field Effects 0.000 description 4
- 230000002238 attenuated effect Effects 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 2
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3005—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3052—Automatic control in amplifiers having semiconductor devices in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver
- H03G3/3068—Circuits generating control signals for both R.F. and I.F. stages
Definitions
- the present invention relates to a receiving apparatus that receives radio waves including an analog audio signal and a control method for the receiving apparatus.
- Some in-vehicle devices mounted on a vehicle include a radio receiver (reception device).
- This type of radio receiver has an antenna amplifier that amplifies an RF (Radio Frequensy) signal that is a received signal received by the antenna, selects a signal of the receiving station from the signal amplified by the antenna amplifier, and demodulates it.
- An analog audio signal from the receiving station is output after processing.
- an AGC Auto Gain Control
- This AGC circuit is also referred to as a RF AGC (Radio Frequency Auto Gain Control) circuit.
- the RF signal is attenuated by a predetermined unit (for example, 6 dB unit), and the S meter level is determined depending on whether the AGC circuit is operated or not. Since the optimum correction values are different, volume changes such as volume fade may occur relatively large.
- the S meter indicates the received electric field strength of the reception frequency, and the optimum value of the S meter level correction is a signal level correction amount determined from the received electric field strength.
- the audio signal level is stable, and the volume change can be kept within an appropriate range. That is, in the conventional configuration, only a fixed value can be quantitatively corrected with respect to the signal level, and it has been difficult to perform volume correction more flexibly.
- the present invention has been made in view of the above-described circumstances, and has a configuration in which the gain of an antenna amplifier unit is variably controlled, and can improve the degree of freedom of volume correction and a control method for the receiving device.
- the purpose is to provide.
- the present invention has an antenna amplifier unit that receives and amplifies a radio wave reception signal including an analog audio signal broadcast from a broadcast station, and the analog audio signal of the reception station is received from the reception signal.
- the AGC circuit unit variably controls the gain of the antenna amplifier unit in a predetermined unit based on the reception intensity of the radio wave, and the receiving station with a different correction amount for each gain of the antenna amplifier unit.
- a volume correction unit that corrects the volume of the audio signal. According to this configuration, the gain of the antenna amplifier unit is variably controlled, and the degree of freedom in volume correction is improved as compared with a configuration that can only perform quantitative correction. As a result, it is possible to perform a suitable volume correction by lowering the volume of the desired signal and improving the S / N ratio for hearing.
- a tuner DSP that inputs an intermediate frequency signal obtained by converting the received signal and performs signal processing is provided, and the tuner DSP has a different correction amount for each gain of the antenna amplifier unit.
- the volume of the audio signal may be corrected. According to this configuration, it is easy to change the receiving device having the conventional tuner DSP to the receiving device of the present invention.
- table data in which an AGCREAD value corresponding to the gain of the antenna amplifier unit is associated with a level offset value indicating the correction amount is stored, and the volume correction unit refers to the table data. Then, the level offset value corresponding to the current AGCREAD value may be specified, and the volume correction may be performed. According to this configuration, a different correction amount can be easily specified for each gain of the front end unit, and the correction amount can be easily changed.
- volume correction unit that corrects the volume in a predetermined unit according to the gain of the antenna amplifier unit may be provided. According to this configuration, it is possible to perform more accurate volume correction while using another conventional volume correction unit. Further, in the above configuration, the volume correction unit attenuates more than a signal level attenuation when the volume correction is performed only by the other volume correction unit in a predetermined region where the intensity of the radio wave is relatively high. In addition to performing volume correction so as to reduce the amount, in a predetermined region where the intensity of the radio wave is relatively low, the attenuation is higher than the attenuation of the signal level when the volume correction is performed only by the other volume correction unit. The volume may be corrected so as to increase.
- the present invention also includes an antenna amplifier unit that receives and amplifies a radio wave reception signal including an analog audio signal broadcast from a broadcast station, and obtains an analog audio signal of the reception station from the reception signal.
- the gain of the antenna amplifier unit is variably controlled based on the reception intensity of the radio wave, and the volume of the audio signal of the receiving station is corrected with a different correction amount for each gain of the antenna amplifier unit. It is characterized by performing. According to this configuration, the gain of the antenna amplifier unit is variably controlled, and the degree of freedom in volume correction is improved as compared with a configuration that can only perform quantitative correction. As a result, it is possible to perform a suitable volume correction by lowering the volume of the desired signal and improving the S / N ratio for hearing.
- the degree of freedom of volume correction can be improved with a configuration in which the gain of the antenna amplifier unit is variably controlled.
- FIG. 1 is a block diagram showing a configuration of an in-vehicle receiving device according to an embodiment of the present invention.
- FIG. 2 is a block diagram showing the configuration of the tuner IC.
- FIG. 3 is a diagram illustrating the relationship between the number of AGCSTEPs and the amount of signal level attenuation.
- FIG. 4 is a flowchart showing the second sound volume correction.
- FIG. 5 shows a correction table.
- FIG. 1 is a block diagram showing a configuration of an in-vehicle receiving device according to an embodiment of the present invention.
- the in-vehicle receiving device 10 is a radio receiving device that is mounted on a vehicle such as an automobile and receives radio waves including analog audio signals broadcast from one or more radio broadcasting stations via an antenna 11 installed in the vehicle.
- the in-vehicle receiving device 10 includes a tuner IC (tuner unit) 21 that converts an RF signal (“RF” in FIG.
- the tuner IC 21 includes a front end portion 31 (“F / E” in FIG. 1) and a back end portion 32 (“B / E” in FIG. 1).
- FIG. 2 is a block diagram showing the configuration of the tuner IC 21.
- the front end unit 31 functions as an antenna amplifier unit for amplifying an RF signal, and includes an AGC circuit 41, an RF-AGC circuit 42, an RF-AMP circuit 43, and a MIX circuit (mixing circuit) 44.
- the AGC circuit 41 and the RF-AGC circuit 42 function as an AGC circuit unit 40 that variably controls the gain of the RF-AMP circuit 43 based on the radio wave reception intensity (RF signal intensity).
- the RF-AMP circuit 43 functions as an amplifying unit that amplifies and outputs the RF signal input to the front end unit 31.
- the AGC circuit 41 detects the signal level of the RF signal input to the RF-AMP circuit 43, and controls the RF-AGC circuit 42 based on this signal level, whereby the RF-AGC circuit
- the RF-AGC voltage output from 42 is variably controlled in multiple stages.
- the RF-AMP circuit 43 variably controls the gain (gain) according to the RF-AGC voltage, and thereby the gain is variably controlled based on the radio wave reception intensity.
- the RF signal can be attenuated when the radio wave reception intensity becomes strong, and the input level to the RF-AMP circuit 43 can be attenuated so as not to exceed a certain level, so that distortion of the amplifier can be suppressed.
- the AGC circuit unit 40 functions as an automatic gain control unit that variably controls the gain in multiple stages so that the amplifier is not distorted.
- a conventional automatic gain control circuit can be widely applied.
- the MIX circuit 44 mixes an RF signal, which is a reception signal output from the RF-AMP circuit 43, with a local oscillator signal (not shown) and an IF (Intermediate Frequency) signal (in FIG. 1, “ IF ”).
- the back end unit 32 includes a tuner DSP (Digital Signal Processor) 46 that performs signal processing on the IF signal output from the front end unit 31.
- DSP Digital Signal Processor
- the tuner DSP 46 is a processing unit that collectively performs processing after the IF signal, and is also referred to as a signal processing tuner.
- the tuner DSP 46 can be broadly divided into a tuner module unit that selects a signal of the receiving station from the IF signal, an analog-digital conversion of the IF signal from the tuner module unit, and outputs the analog signal to the audio processor unit.
- An analog interface unit that converts a digital audio signal into an analog audio signal SA and outputs the analog audio signal SA, and an audio processor unit that performs various radio processing and audio processing on the digital IF signal input from the analog interface unit. .
- radio processing digital processing such as noise removal processing and demodulation processing is executed
- audio processing digital processing such as volume control and sound quality control is executed.
- the analog signal SA of the receiving station is output from the tuner DSP 46 and supplied to the amplifier 24 (FIG. 1), and the speaker 25 is driven by the amplifier 24 and the radio sound desired by the user is emitted.
- the AGC circuit unit 40 is configured to attenuate the gain of the RF-AMP circuit 43 by a certain unit (6 dB unit in the present embodiment), and the volume of the AGC circuit unit 40 depends on whether the AGC circuit unit 40 operates or not. There was a case where the change was relatively large or the noise on the audibility was conspicuous.
- the tuner DSP 46 adjusts the volume in a fixed unit (3 dB unit in the present embodiment) in accordance with the attenuation level by the AGC circuit unit 40 (hereinafter referred to as “first volume”).
- a first volume correction unit (quantitative volume correction unit) 47 that performs “correction”).
- This first volume correction unit 47 suppresses a change in volume to some extent, and if the S / N is high, the volume Is reduced to a certain extent to reduce noise in the sense of hearing.
- the first sound volume correction unit 47 includes an algorithm process for performing the first sound volume correction and data necessary for the algorithm process, and the tuner process is executed by executing the algorithm process according to a predetermined program.
- the DSP 46 functions as the first sound volume correction unit 47.
- FIG. 3 shows the relationship between the gain of the RF-AMP circuit 43, that is, the number of AGCSTEPs indicating the amount of attenuation, and the amount of attenuation of the signal level.
- a characteristic curve f1 indicated by a solid line indicates a case where no sound volume correction is performed, that is, a case where attenuation is performed in units of 6 dB.
- a characteristic curve f2 indicated by a broken line indicates a case where the first sound volume correction is performed.
- the tuner DSP 46 performs the volume correction (hereinafter referred to as “second volume correction”) with a different correction amount for each gain (attenuation amount) of the RF-AMP circuit 43. To have.
- the second sound volume correction unit 48 includes an algorithm process for performing a second sound volume correction and a correction table T1 described later, and the tuner DSP 46 performs the first process by executing the algorithm process according to a predetermined program. It also functions as a two-volume correction unit 48.
- FIG. 4 is a flowchart showing the second sound volume correction.
- the volume correction is a process that is started when the in-vehicle receiving device 10 is turned on and starts receiving a signal.
- the tuner DSP 46 sets the AGC comparison value N to a value 0 (step S1), and acquires an AGCREAD value indicating the AGC operation status via the AGC circuit 41 (step S2).
- the AGCREAD value is information corresponding to the gain (attenuation amount) of the RF-AMP circuit 43, for example, information that matches the number of AGCSTEP described above.
- the tuner DSP 46 compares the acquired AGCREAD value with the AGC comparison value N (step S3).
- step S3 If the AGCREAD value does not match the AGC comparison value N (step S3; NO), the tuner DSP 46 sets the AGC comparison value N to the AGC comparison value N. After incrementing 1 (step 4), the process proceeds to step S3, where it is determined again whether the AGCREAD value and the AGC comparison value N match.
- the value N is incremented until the AGCREAD value and the AGC comparison value N match each other (step S3; YES), and the tuner DSP 46 determines from the correction table T1 described later that the level offset corresponding to the current AGCREAD value.
- a value is specified, and this level offset value is set (step S5).
- the process proceeds to step S1, and the above process is repeated.
- the level offset value is set according to the gain of the RF-AMP circuit 43, and when the level offset value is set, the tuner DSP 46 determines the level of the audio signal of the receiving station based on the set level offset value. By performing the correction, the volume of the audio signal SA is corrected.
- FIG. 5 shows the correction table T1.
- the correction table T1 is table data in which the AGCREAD value and the level offset value are associated with each other on a one-to-one basis.
- the AGCREAD value is set to a value 0 to N
- the value 0 corresponds to the value 0 of the AGC STEP number shown in FIG. 3
- the value 1 corresponds to the value 1 of the AGC STEP number
- the value N is the AGC STEP number Corresponds to the value N. That is, when the AGCREAD value is 0, the attenuation amount in the RF-AMP circuit 43 is zero, and the attenuation amount in the RF-AMP circuit 43 increases as the AGCREAD value increases.
- FIG. 5 shows the correction table T1.
- the correction table T1 is table data in which the AGCREAD value and the level offset value are associated with each other on a one-to-one basis.
- the AGCREAD value is set to a value 0 to N
- the value 0 corresponds to the value
- a level offset value of 0 is assigned to the value 0 of the AGCREAD value.
- level offset values X1 to XN are individually assigned. These level offset values are set in consideration of the operation state of the AGC circuit unit 40 in a running test in which the in-vehicle receiving device 10 is mounted on an actual vehicle and the influence of an interference signal on a desired signal (audio signal of the receiving station). Points to consider include interference of interference signals to the desired signal, volume reduction of the desired signal, S / N deterioration of the desired signal, and a level offset value that improves the volume reduction and S / N deterioration of the desired signal. Each is set independently.
- a characteristic curve f3 indicated by a one-dot chain line in FIG. 3 shows a specific example when level correction is performed with a level offset value based on the correction table T1 (when the second volume correction is further performed). .
- the level offset value is set so as to reduce the attenuation amount as compared with the characteristic curve f2, as indicated by the characteristic curve f3 in FIG. Specifically, when the AGC STEP number is 1, the attenuation amount is ⁇ 3 dB in the characteristic curve f2, whereas in the characteristic curve f3, the level offset value X1 is ⁇ 2 dB.
- the attenuation amount is ⁇ 6 dB in the characteristic curve f2, whereas in the characteristic curve f3, ⁇ 2 dB is set by the level offset value X2.
- the attenuation amount is ⁇ 9 dB in the characteristic curve f2, whereas in the characteristic curve f3, the level is set to ⁇ 7 dB by the level offset value X3.
- the area AR2 is a situation in which the level of the interference signal is high and it is difficult to obtain a sufficient S / N.
- the level offset value is set so that the attenuation amount is increased more than the characteristic curve f2.
- the attenuation amount is ⁇ 12 dB in the characteristic curve f2
- the level offset value X4 is set to ⁇ 14 dB.
- the attenuation amount is ⁇ 15 dB in the characteristic curve f2, whereas in the characteristic curve f3, it is ⁇ 18 dB by the level offset value X5.
- the characteristic curve 3 is obtained by increasing the attenuation compared to the case of the characteristic curve 2.
- the gain of the front end unit 31 functioning as an antenna amplifier unit is variably controlled by a predetermined unit based on the radio wave reception intensity by the AGC circuit unit 40, and the second volume correction of the tuner DSP 46 is performed. Since the volume correction is performed with a different correction amount for each gain of the front end section 31 by the section 48, the degree of freedom in volume correction is improved as compared with the one that can only perform quantitative correction, and the volume of the desired signal is reduced and the audibility is increased. It is possible to perform a suitable volume correction by improving the S / N ratio. Note that it is not always necessary that the correction amount for each gain of the front end unit 31 is different, and the same correction amount can be set.
- the tuner DSP 46 that performs signal processing on the IF signal corrects the sound volume with a different correction amount for each gain of the front end unit 31, so that the in-vehicle receiving device 10 of the present invention is changed from the in-vehicle receiving device having the conventional tuner DSP. Easy to change to. For example, it is possible to respond by exchanging the tuner DSP or adding a function to the tuner DSP.
- the correction table T1 in which the AGCREAD value corresponding to the gain of the front end unit 31 is associated with the level offset value indicating the correction amount is stored, and the current AGCREAD is referred to with reference to the correction table T1. Since the level offset value corresponding to the value is specified and the sound volume is corrected, a different correction amount for each gain of the front end unit 31 can be easily specified, and the correction amount can be easily changed.
- the in-vehicle receiving device 10 having this configuration includes a first volume correction unit (another volume correction unit) 48 that corrects the volume in a predetermined unit for each gain of the front end unit 31, the first volume correction unit 47 is provided.
- the volume correction that is still insufficient even when used can be compensated by the second volume correction unit 48.
- the amount of volume correction (second volume correction) using the correction table T1 can be reduced by the amount of correction performed by the first volume correction unit 47.
- the above-described embodiment is merely one aspect of the present invention, and can be arbitrarily modified within the scope of the present invention.
- the case where the in-vehicle reception device 10 includes the first sound volume correction unit 47 has been described.
- the present invention is not limited thereto, and the first sound volume correction unit 47 may be omitted.
- the case where the present invention is applied to the in-vehicle receiving device 10 has been described.
- the present invention is not limited to this, and the receiving device included in the in-vehicle device such as a car navigation device or an in-vehicle acoustic device for reproducing a CD or the like. Can be widely applied to.
- the present invention may be applied to a receiving device other than the in-vehicle device or an electronic device having the receiving device.
- Tuner IC (tuner part) 31 Front end (antenna amplifier) 32 Back-end unit 40 AGC circuit unit 41 AGC circuit 42 RF-AGC circuit 43 RF-AMP circuit (amplification unit) 44 MIX circuit (mixed circuit) 46 Tuner DSP (Signal Processing Tuner) 47 First volume correction unit (quantitative volume correction unit) 48 Second sound volume correction unit T1 correction table (table data)
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Abstract
Description
従来、受信電波強度に応じてアンテナアンプ部の利得を可変制御するAGC(Auto Gain Control)回路を備え、電界強度が強くなるとRF信号を減衰させ、増幅器の歪みを抑えるものがある(例えば、特許文献1参照)。このAGC回路は、RFAGC(Radio Frequensy Auto Gain Control)回路とも称される。
なお、Sメーターは、受信周波数の受信電界強度を示し、Sメーターレベル補正の最適値は、その受信電界強度から決まる信号レベル補正量であり、この最適値にレベル補正される場合には音声信号の信号レベルは安定し、音量変化も適正範囲内に抑えられる。
つまり、従来の構成では、信号レベルに対して固定値で定量的な補正しかできず、より柔軟に音量補正を行うことが難しかった。
この構成によれば、アンテナアンプ部の利得を定量的に可変制御する構成で、定量的な補正しかできないものと比べて、音量補正の自由度が向上する。これによって、希望信号の音量低下と聴感上のS/N改善とにより好適な音量補正を行うことが可能になる。
また、上記構成において、前記音量補正部は、前記電波の強度が相対的に高い予め定めた領域では、前記他の音量補正部だけで音量補正を行った場合の信号レベルの減衰量よりも減衰量を減らすように音量補正を行うとともに、前記電波の強度が相対的に低い予め定めた領域では、前記他の音量補正部だけで音量補正を行った場合の信号レベルの減衰量よりも減衰量を増やすように音量補正を行うようにしても良い。この構成によれば、十分なS/Nを得やすい状況では音量低下をより抑えることができ、十分なS/Nを得にくい状況では音量をより下げて聴感上のノイズを減らすことができる。
図1は、本発明の実施形態に係る車載受信装置の構成を示すブロック図である。
この車載受信装置10は、自動車などの車両に搭載され、車両に設置されたアンテナ11を介して一又は複数のラジオ放送局から放送されるアナログ音声信号を含む電波を受信するラジオ受信装置である。
同図1に示すように、車載受信装置10は、アンテナ11が受信した受信信号であるRF信号(図1中、「RF」)を音声信号SAに変換するチューナーIC(チューナー部)21と、チューナーIC21を制御するマイコン22と、チューナーIC21を制御するための各種データを保持するメモリ23と、音声信号SAを入力して外部のスピーカー25を駆動するアンプ24とを備えている。
チューナーIC21は、フロントエンド部31(図1中、「F/E」)と、バックエンド部32(図1中、「B/E」)とを備えている。
フロントエンド部31は、RF信号を増幅するアンテナアンプ部などとして機能するものであり、AGC回路41と、RF-AGC回路42と、RF-AMP回路43と、MIX回路(混合回路)44とを備えている。
AGC回路41およびRF-AGC回路42は、電波の受信強度(RF信号の強度)に基づいて、RF-AMP回路43の利得を可変制御するAGC回路部40として機能するものである。また、RF-AMP回路43は、フロントエンド部31に入力されたRF信号を増幅して出力する増幅部として機能するものである。
RF-AMP回路43は、RF-AGC電圧に応じて利得(ゲイン)を可変制御し、これによって、電波の受信強度に基づいて利得が可変制御される。
以上の構成により、電波の受信強度が強くなるとRF信号を減衰させ、RF-AMP回路43への入力レベルが一定レベル以上にならないように減衰させることができ、増幅器の歪みを抑えることができる。
このように、AGC回路部40は、増幅器が歪まないように利得を多段階で可変制御する自動利得制御部として機能する。このAGC回路部40については、従来の自動利得制御回路を広く適用することができる。
バックエンド部32は、フロントエンド部31から出力されるIF信号に対して信号処理を行うチューナーDSP(Digital Signal Processor)46を備えている。
ラジオ処理としては、ノイズ除去処理や復調処理などのデジタル処理が実行され、オーディオ処理としては、音量コントロールや音質コントロールなどのデジタル処理が実行される。
このようにして、チューナーDSP46からは受信局のアナログ音声信号SAが出力されてアンプ24(図1)に供給され、アンプ24によりスピーカー25が駆動され、ユーザーが所望するラジオ音声が放音される。
なお、第1音量補正部47は、第1の音量補正を行うためのアルゴリズム処理と、このアルゴリズム処理に必要なデータとによって構成され、所定のプログラムに従って上記アルゴリズム処理が実行されることによって、チューナーDSP46が第1音量補正部47として機能するようになっている。
この図3において、実線で示す特性曲線f1は、音量補正を全く行わない場合を示し、つまり、6dB単位で減衰させる場合を示している。また、破線で示す特性曲線f2は、第1の音量補正を行った場合を示している。
そこで、本構成では、チューナーDSP46が、RF-AMP回路43の利得(減衰量)毎に異なる補正量で音量補正(以下、「第2の音量補正」と言う)を行う第2音量補正部48を有するようにしている。
この第2音量補正部48は、第2の音量補正を行うためのアルゴリズム処理と、後述する補正テーブルT1とで構成され、所定のプログラムに従って上記アルゴリズム処理が実行されることによって、チューナーDSP46が第2音量補正部48としても機能するようになっている。
まず、チューナーDSP46は、AGC比較値Nを値0に設定し(ステップS1)、AGC回路41を介してAGC動作状況を示すAGCREAD値を取得する(ステップS2)。ここで、AGCREAD値は、RF-AMP回路43の利得(減衰量)に対応する情報であり、例えば、上記したAGCSTEP数と一致する情報である。
続いて、チューナーDSP46は、取得したAGCREAD値と、AGC比較値Nとを比較し(ステップS3)、AGCREAD値とAGC比較値Nとが一致しない場合(ステップS3;NO)、AGC比較値Nに1をインクリメントした後(ステップ4)、ステップS3に移行し、AGCREAD値とAGC比較値Nとが一致したか否かを再判定する。
このようにしてRF-AMP回路43の利得に応じてレベルオフセット値が設定され、レベルオフセット値が設定されると、チューナーDSP46は、設定されたレベルオフセット値に基づいて受信局の音声信号のレベル補正を行うことによって音声信号SAの音量補正を行う。
図5に示すように、補正テーブルT1は、AGCREAD値と、レベルオフセット値とを一対一で対応づけたテーブルデータである。
AGCREAD値は、値0~Nまで設定され、値0が図3に示すAGCSTEP数の値0に対応し、値1がAGCSTEP数の値1に対応し、・・・、値NがAGCSTEP数の値Nに対応している。
つまり、AGCREAD値が値0では、RF-AMP回路43での減衰量は零であり、AGCREAD値が大きいほどRF-AMP回路43での減衰量が大きくなる。
同図5に示すように、AGCREAD値の値0には、値0のレベルオフセット値が割り当てられる。これにより、減衰量が零の場合、つまり、RF信号の強度(受信電界強度)が最も高い場合には、レベルオフセット値が零に設定され、何らレベル補正せず、音量を低下させないようにしている。
これらのレベルオフセット値は、車載受信装置10を実車に搭載した走行テストでのAGC回路部40の動作状況および希望信号(受信局の音声信号)に対する妨害信号の影響を考慮して設定される。考慮する点としては、希望信号への妨害信号の混信、希望信号の音量低下、希望信号のS/N悪化などであり、希望信号の音量低下とS/N悪化とを改善するレベルオフセット値が各々独立して設定される。
ここで、図3中、一点鎖線で示す特性曲線f3は、補正テーブルT1に基づくレベルオフセット値でレベル補正を行った場合(第2の音量補正を更に行った場合)の具体例を示している。
領域AR1では、妨害信号のレベルが低く、希望信号のレベルもある程度確保されるため、十分なS/Nを得やすい状況である。このため、領域AR1では、図3に特性曲線f3で示すように、特性曲線f2よりも減衰量を減らすようにレベルオフセット値が設定される。
具体的には、AGCSTEP数が値1では、特性曲線f2では減衰量が-3dBであるのに対し、特性曲線f3では、レベルオフセット値X1によって-2dBとされる。また、AGCSTEP数が値2では、特性曲線f2では減衰量が-6dBであるのに対し、特性曲線f3では、レベルオフセット値X2によって-2dBとされる。また、AGCSTEP数が値3では、特性曲線f2では減衰量が-9dBであるのに対し、特性曲線f3では、レベルオフセット値X3によって-7dBとされる。
これによって、十分なS/Nを得やすい状況では音量低下をより抑えることができる。
具体的には、AGCSTEP数が値4では、特性曲線f2では減衰量が-12dBであるのに対し、特性曲線f3では、レベルオフセット値X4によって-14dBとされる。また、AGCSTEP数が値5では、特性曲線f2では減衰量が-15dBであるのに対し、特性曲線f3では、レベルオフセット値X5によって-18dBとされる。また、AGCSTEP数が値6,7でも、特性曲線2の場合よりも減衰量を増やした特性曲線3とされる。
これによって、十分なS/Nを得にくい状況では音量をより下げて聴感上のノイズを減らしている。
また、IF信号に対して信号処理を行うチューナーDSP46が、フロントエンド部31の利得毎に、異なる補正量で音量補正するので、従来のチューナーDSPを有する車載受信装置から本発明の車載受信装置10への変更が容易である。例えば、チューナーDSPの交換又はチューナーDSPへの機能追加などで対応するようにすることができる。
さらに、上述の実施形態では、車載受信装置10に本発明を適用する場合を説明したが、これに限らず、カーナビゲーション装置やCD等を再生する車載音響装置などの車載装置が具備する受信装置に広く適用することができる。また、車載装置以外の受信装置、或いは受信装置を有する電子機器に本発明を適用しても良い。
21 チューナーIC(チューナー部)
31 フロントエンド部(アンテナアンプ部)
32 バックエンド部
40 AGC回路部
41 AGC回路
42 RF-AGC回路
43 RF-AMP回路(増幅部)
44 MIX回路(混合回路)
46 チューナーDSP(信号処理チューナー)
47 第1音量補正部(定量的音量補正部)
48 第2音量補正部
T1 補正テーブル(テーブルデータ)
Claims (6)
- 放送局から放送されるアナログ音声信号を含む電波の受信信号を入力して増幅するアンテナアンプ部を有し、前記受信信号から受信局のアナログ音声信号を取得する受信装置において、
前記電波の受信強度に基づいて、前記アンテナアンプ部の利得を所定単位で可変制御するAGC回路部と、
前記アンテナアンプ部の利得毎に、異なる補正量で前記受信局の音声信号の音量補正を行う音量補正部とを有することを特徴とする受信装置。 - 前記受信信号を変換して得られる中間周波信号を入力し、信号処理を行うチューナーDSPを備え、
前記チューナーDSPが、前記アンテナアンプ部の利得毎に、異なる補正量で前記受信局の音声信号の音量補正を行うことを特徴とする請求項1に記載の受信装置。 - 前記アンテナアンプ部の利得に対応するAGCREAD値と、前記補正量を示すレベルオフセット値とを対応づけたテーブルデータを記憶し、
前記音量補正部は、前記テーブルデータを参照して、現在のAGCREAD値に対応するレベルオフセット値を特定し、音量補正を行うことを特徴とする請求項1に記載の受信装置。 - 前記アンテナアンプ部の利得に応じて所定単位で音量補正する他の音量補正部を有することを特徴とする請求項1に記載の受信装置。
- 前記音量補正部は、前記電波の強度が相対的に高い予め定めた領域では、前記他の音量補正部だけで音量補正を行った場合の信号レベルの減衰量よりも減衰量を減らすように音量補正を行うとともに、前記電波の強度が相対的に低い予め定めた領域では、前記他の音量補正部だけで音量補正を行った場合の信号レベルの減衰量よりも減衰量を増やすように音量補正を行うことを特徴とする請求項1に記載の受信装置。
- 放送局から放送されるアナログ音声信号を含む電波の受信信号を入力して増幅するアンテナアンプ部を有し、前記受信信号から受信局のアナログ音声信号を取得する受信装置の制御方法において、
前記電波の受信強度に基づいて、前記アンテナアンプ部の利得を定量的に可変制御し、
前記アンテナアンプ部の利得毎に、異なる補正量で前記受信局の音声信号の音量補正を行うことを特徴とする受信装置の制御方法。
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US14/762,293 US20150357984A1 (en) | 2013-01-22 | 2013-10-24 | Receiving device and control method for receiving device |
CN201380071021.6A CN104937851A (zh) | 2013-01-22 | 2013-10-24 | 接收装置以及接收装置的控制方法 |
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JP2002353830A (ja) * | 2001-05-24 | 2002-12-06 | Mitsubishi Electric Corp | Amラジオ受信装置およびそのagc特性補正方法 |
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TWI429301B (zh) * | 2008-05-05 | 2014-03-01 | Mstar Semiconductor Inc | 音量控制裝置與方法 |
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CN104937851A (zh) | 2015-09-23 |
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