JP2011211263A - Broadcast receiver and broadcasting signal processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain harmony between suppression of generating of sense of incongruity on acoustic feeling in a listener and outputting of proper reproduction sound.SOLUTION: A detection signal DTDis obtained by detecting an adaptive filtering processing result by an adaptation filter unit 130 for an intermediate frequency signal IFD. A detection signal DTDis obtained by detecting a delay processing result by a delay unit 140 for the intermediate frequency signal IFD. A control unit 190 compares the detection signal DTDwith the detection signal DTD. Subsequently, the control unit 190 evaluates a mixing rate of a disturbance signal in the intermediate frequency signal IFD. Then, the control unit 190 computes a weighting factor CFto the detection signal DTDand a weighting factor CFto the detection signal DTDbased on the evaluated mixing rate. According to the weighting factors CFand CFdetermined in this way, a weighting addition portion 152 performs weighting addition for the detection signal DTDand the detection signal DTD, and generates a signal WAD as a subject of stereo demodulation processing.

Description

  The present invention relates to a broadcast receiving apparatus, a broadcast signal processing method, a broadcast signal processing program, and a recording medium on which the broadcast signal processing program is recorded.

  2. Description of the Related Art Conventionally, a car radio broadcast receiving apparatus that receives and processes radio broadcast waves and reproduces sound is mounted on many vehicles. In such a car radio broadcast receiver, the reception level of the radio broadcast wave changes suddenly due to the influence of reflected waves from surrounding buildings caused by the movement of the vehicle, or the frequency band of the selected desired station A multipath phenomenon in which the phase of the signal fluctuates occurs. When such a multipath phenomenon occurs, the reception quality deteriorates.

  For this reason, in order to obtain a signal in which the influence of the multipath phenomenon is suppressed, a technique has been proposed that employs an adaptive filter that adaptively performs filtering processing on an intermediate frequency signal of a broadcast wave (see Patent Document 1). Hereinafter, it will be referred to as “conventional example 1”). The technology of Conventional Example 1 is a technology related to an FM broadcast wave receiving apparatus, and adopts a CMA (Constant Modulus Algorithm) as an adaptive filtering processing algorithm in consideration that the FM broadcast wave is originally constant in amplitude. When adaptive filtering processing employing an adaptive filtering processing algorithm such as CMA is performed, generally, even if the field strength of the broadcast wave of the desired station is weak, it follows the signal with the strongest field strength in the band. There is also an effect of reducing background noise sound in the reproduced sound.

  In addition, in order to obtain a signal in which the influence of the multipath phenomenon is suppressed, a technique for correcting the desired station signal to a predetermined signal level based on the electric field strength of the broadcast wave of the same frequency band received by each of the plurality of antennas. Has also been proposed (see Patent Document 2: hereinafter referred to as “Conventional Example 2”). In the technique of Conventional Example 2, the electric field strength of the broadcast wave in the same frequency band received by each of the plurality of antennas is detected, and received by each of the plurality of antennas using the weighting coefficient determined based on the detection result. After performing the weighted addition of the signals, a process for setting the result of the addition to a predetermined level is performed to generate a reproduction signal.

WO 2006/103922 A1 JP 2009-141478 A

  In the technique of Conventional Example 1 described above, an adaptive filtering algorithm that follows a signal having the strongest electric field strength in the broadcast wave band of the desired station is generally employed. For this reason, in the technique of Conventional Example 1, there is an adjacent station having a frequency close to the frequency of the desired station on the frequency axis, and a reception signal corresponding to the adjacent station enters the frequency band of the desired station at a large rate. When it comes, the phenomenon that the sound corresponding to the broadcast wave of the adjacent station suddenly starts to sound clearly occurs. Further, in the technique of Conventional Example 1, if a strong beat signal exists when the desired station signal is weak, a phenomenon occurs in which sound corresponding to the broadcast wave of the desired station is not output. Occurrence of these phenomena makes the listener feel uncomfortable.

  In the technique of Conventional Example 2 described above, since it is necessary to prepare a plurality of antennas, the apparatus configuration becomes complicated. Further, in the technique of Conventional Example 2, since the adaptive filtering process is not performed on the received signal, it is difficult to effectively suppress the influence of the multipath phenomenon. Furthermore, in the technique of the conventional example 2, when the electric field intensity of the broadcast wave of the desired station is weak, the effect of reducing the background noise sound in the reproduced sound cannot be expected.

  For this reason, there is a demand for a technology capable of outputting high-quality reproduced sound while suppressing the generation of a sense of discomfort in the listener with respect to a broadcast receiver that moves with a vehicle such as a car radio broadcast receiver. Meeting this requirement is one of the problems to be solved by the present invention.

  The present invention has been made in view of the above circumstances, and a broadcast receiving apparatus and broadcast signal processing capable of achieving harmony between suppression of occurrence of discomfort in the listener and output of high-quality reproduced sound It aims to provide a method.

  The invention according to claim 1 is a broadcast receiving device mounted on a mobile body, wherein adaptive filter means for adaptively filtering an intermediate frequency signal of a broadcast wave; and filtering processing by the adaptive filter means First detection means for detecting the signal subjected to the delay; delay means for delaying the intermediate frequency signal of the broadcast wave by a processing delay time by the adaptive filter means; detection of the signal delayed by the delay means Second detection means for performing; weighting addition of the first detection signal obtained by the first detection means and the second detection signal obtained by the second detection means; and the first detection signal And the second detection signal are compared, and based on the result of the comparison, the weight coefficient of the first detection signal and the second detection signal at the time of addition by the adding means is determined. A broadcast receiving apparatus characterized by comprising; means and.

  The invention according to claim 6 is an adaptive filter means for adaptively filtering an intermediate frequency signal of a broadcast wave; and a first detection means for detecting a signal subjected to the filtering process by the adaptive filter means A delay means for delaying the intermediate frequency signal of the broadcast wave by a processing delay time by the adaptive filter means; and a second detection means for detecting the signal delayed by the delay means; A broadcast signal processing method used in a broadcast receiving apparatus mounted on a body, wherein the first detection signal obtained by the first detection means is compared with the second detection signal obtained by the second detection means. A comparison step to perform; a weight determination step to determine a weight coefficient of the first detection signal and the second detection signal based on a comparison result in the comparison step; A broadcast signal processing method characterized in that it comprises a; using a weighting factor, and adding step performs weighted addition of the first detection signal and the second detection signal.

  According to a seventh aspect of the present invention, there is provided a broadcast signal processing program characterized by causing a calculation means to execute the broadcast signal processing method according to the sixth aspect.

  The invention according to claim 8 is a recording medium in which the broadcast signal processing program according to claim 7 is recorded so as to be readable by the calculation means.

It is a block diagram which shows roughly the structure of the FM receiver 100 which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the adaptive filter unit 130 of FIG. FIG. 2 is a block diagram showing a configuration of a reproduction processing unit 150 in FIG. It is a block diagram which shows the structure of the control unit 190 of FIG. FIG. 5 is a block diagram showing a configuration of BPF units 226 ₁ and 226 ₂ and level detection units 227 ₁ and 227 ₂ in FIG. FIG. 6 is a diagram illustrating characteristics of individual BPF units 226 ₁₁ and 226 _{21 in} FIG. 5. FIG. 6 is a diagram illustrating characteristics of individual BPF units 226 ₁₂ and 226 _{22 in} FIG. 5. 6 is a flowchart for explaining weighting factor determination processing by the processing control unit 229 of FIG. 4. It is a diagram for explaining a weighting factor CF _1, CF _2, which is determined by the processing of FIG. Diagram for explaining a weighting factor CF _1, CF ₂ according to a modified example; FIG. FIG. 6 is a diagram (part 2) for explaining weighting factors CF ₁ and CF _{2 according} to a modification. FIG. 11 is a diagram ( _No. 3) for explaining weighting factors CF ₁ and CF _{2 according} to a modification.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In the following description and drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

[Constitution]
FIG. 1 is a block diagram illustrating a schematic configuration of an FM receiver 100 that is a broadcast receiver according to an embodiment. As shown in FIG. 1, the FM receiver 100 includes an antenna 110 and an RF processing unit 120. The FM receiver 100 includes an adaptive filter unit 130 as an adaptive filter unit, a delay unit 140 as a delay unit, a reproduction processing unit 150, and an analog processing unit 160. Further, the FM receiver 100 includes a speaker unit 170, an operation input unit 180, and a control unit 190.

  The antenna 110 receives a broadcast wave. A reception result by the antenna 110 is sent to the RF processing unit 120 as a reception signal RFS.

  The RF processing unit 120 performs channel selection processing for extracting a signal of a desired station to be selected from the received signal RFS in accordance with the channel selection command CSL sent from the control unit 190, and obtains a component of a predetermined intermediate frequency band. The intermediate frequency signal IFD is sent to the adaptive filter unit 130 and the delay unit 140. The RF processing unit 120 includes an input filter, a high-frequency amplifier (RF-AMP: Radio Frequency-Amplifier), and a band-pass filter (hereinafter also referred to as “RF filter”). The RF processing unit 120 includes a mixer (mixer), an intermediate frequency filter (hereinafter also referred to as “IF filter”), an AD (Analogue to Digital) converter, and a local oscillation circuit (OSC). Yes.

  Here, the input filter is a high-pass filter that blocks low frequency components of the reception signal RFS transmitted from the antenna 110. The high frequency amplifier amplifies the signal that has passed through the input filter. The RF filter selectively passes a signal in a high frequency band among signals output from the high frequency amplifier. The mixer mixes the signal that has passed through the RF filter and the local oscillation signal supplied from the local oscillation circuit.

  The IF filter selects and passes a signal in a predetermined intermediate frequency range among the signals output from the mixer. The AD converter converts the signal that has passed through the IF filter into a digital signal. This conversion result is sent to the adaptive filter unit 130 and the delay unit 140 as an intermediate frequency signal IFD.

  Note that the local oscillation circuit includes an oscillator that can control the oscillation frequency by voltage control or the like. This local oscillation circuit generates a local oscillation signal having a frequency corresponding to a desired station to be selected in accordance with a channel selection command CSL sent from the control unit 190, and supplies it to the mixer.

  The adaptive filter unit 130 receives the intermediate frequency signal IFD sent from the RF processing unit 120. Then, the adaptive filter unit 130 performs a filtering process for removing the distortion of the received signal due to so-called multipath generation. The result of the filtering process by the adaptive filter unit 130 is sent to the reproduction processing unit 150 as a signal FLD. The configuration of the adaptive filter unit 130 will be described later.

  The delay unit 140 receives the intermediate frequency signal IFD sent from the RF processing unit 120. Then, the delay unit 140 delays the intermediate frequency signal IFD by a time corresponding to the delay due to the filtering process of the adaptive filter unit 130 described above. The delay result by the delay unit 140 is sent to the reproduction processing unit 150 and the control unit 190 as a signal DLD.

The regeneration processing unit 150 receives the signal FLD sent from the adaptive filter unit 130 and the signal DLD sent from the delay unit 140. Then, the reproduction processing unit 150 performs detection processing on the signals FLD and DLD, and sends detection results to the control unit 190 as detection signals DTD ₁ and DTD ₂ .

Further, the reproduction processing unit 150 weights and adds the detection results of the signals FLD and DLD according to the weighting factors CF ₁ and CF ₂ sent from the control unit 190. Then, the reproduction processing unit 150 performs stereo demodulation processing on the addition result. This stereo demodulation result is sent to the analog processing unit 160 as a signal DMD.

  The configuration of the reproduction processing unit 150 will be described later.

  The analog processing unit 160 receives the signal DMD sent from the reproduction processing unit 150. Then, the analog processing unit 160 generates an output audio signal AOS under the control of the control unit 190 and sends it to the speaker unit 170.

  The analog processing unit 160 having such a function includes a DA (Digital to Analogue) conversion unit, a volume adjustment unit, and a power amplification unit. Here, the DA converter receives the signal DMD sent from the reproduction processing unit 150. The DA converter converts the signal DMD into an analog signal. The DA conversion unit corresponds to two DAs configured in the same manner corresponding to the left channel (hereinafter “L channel”) signal and the right channel (hereinafter “R channel”) signal included in the signal DMD. (Digital to Analogue) converter. The analog conversion result by the DA conversion unit is sent to the volume adjustment unit.

  The volume adjustment unit receives the analog conversion result signals of the L channel and the R channel sent from the DA conversion unit. Then, the volume adjustment unit performs volume adjustment processing on the analog conversion result signal corresponding to each of the L channel and the R channel in accordance with the volume adjustment command VLC from the control unit 190. In the present embodiment, the volume adjustment unit is configured to include two electronic volume elements that are configured in the same manner, corresponding to the L channel and the R channel. The signal resulting from the adjustment by the volume adjustment unit is sent to the power amplification unit.

  The power amplifying unit receives the signals of the volume adjustment results of the L channel and the R channel sent from the volume adjusting unit. The power amplification unit power-amplifies the signal of the volume adjustment result. The power amplifying unit includes two power amplifiers configured similarly to each other, corresponding to the L channel and the R channel. An output audio signal AOS that is an amplification result by the power amplification unit is sent to the speaker unit 170.

  The speaker unit 170 includes an L channel speaker and an R channel speaker. The speaker unit 170 reproduces and outputs audio in accordance with the output audio signal AOS sent from the analog processing unit 160.

  The operation input unit 180 includes a key unit provided in the main body of the FM receiver 100 or a remote input device including the key unit. Here, as a key part provided in the main body, a touch panel provided in a display unit (not shown) can be used. Moreover, it can replace with the structure which has a key part, and the structure which inputs voice can also be employ | adopted. The result of operation input to the operation input unit 180 is sent to the control unit 190 as operation input data IPD.

  The control unit 190 performs overall control of the operation of the FM receiver 100. The configuration of the control unit 190 will be described later.

Next, the configuration of the adaptive filter unit 130 will be described. In this embodiment, the adaptive filter unit 130 is configured as an IIR (Infinite Impulse Response) type filter, and as shown in FIG. 2, an adder 212, 2N delay units 213 _{1 to} 231 _2N , (2N + 1) coefficient multipliers 214 _{0 to} 214 _2N , an adder 215, and a coefficient update unit 216 are provided.

The adder 212 receives the intermediate frequency signal IFD sent from the RF processing unit 120 and the signal YF sent from the adder 215. The adder 212 adds the intermediate frequency signal IFD and the signal YF to generate a signal X ₀ (T). The signal X ₀ (T) generated in this way is sent to the delay unit 213 ₁ and the coefficient multiplier 214 ₀ .

Each of the delay devices 213 _j (j = 1 to 2N) delays the input signal X _j−1 (T) by a unit delay time τ and outputs it as a signal X _j (T). As a result, the relationship between the signal X _j (T) and the signal X ₀ (T) is expressed by the following equation (1).
X _j (T) = X ₀ (T−j · τ) (1)

In the present embodiment, each of the delay devices 213 _j samples and outputs the signal X _j−1 (T) in synchronization with a reference clock (not shown) having a period τ. For this reason, during the unit delay time τ, the sampling result is held in the delay unit 213 _j and output. Here, the unit delay time τ is ¼ of the signal period.

The signal X _j (T) generated by the delay unit 213 _j is sent to the coefficient multiplier 214 _j . Here, the signal X _N (T) (= Y (T)) generated by the delay unit 213 _N is also sent to the reproduction processing unit 150 as the signal FLD. Incidentally, the coefficient multipliers 214 _0, so that as described above, the signal X ₀ (T) is sent.

Each of the coefficient multipliers 214 _m (m = 0 to 2N) receives the signal X _m (T) and the tap coefficient K _m (T) from the coefficient update unit 216. Then, the coefficient multiplier 214 _m multiplies the signal X _m (T) by the tap coefficient K _m (T). The result of this multiplication is sent to adder 215.

The adder 215 receives the multiplication results [X ₀ (T) · K ₀ (T)] to [X _2N (T) · K _2N (T)] by the coefficient multipliers 214 _{0 to} 214 _2N . Then, the adder 215 calculates the signal YF (T) by the following equation (2).
YF (T) = X ₀ (T) · K ₀ (T) +… + X _2N (T) · K _2N (T) (2)
The signal YF (T) calculated in this way is sent to the adder 212.

The coefficient updating unit 216 receives the signal X ₀ (T) sent from the adder 212 and the signals X ₁ (T) to X _2N (T) sent from the delay units 213 _{1 to} 213 _2N . Then, the coefficient updating unit 216 calculates tap coefficients K ₀ (T) to K _2N (T) using a CMA (Constant Modulus Algorithm) algorithm. The tap coefficient K _m (T) (m = 0 to 2N) calculated in this way is sent to the coefficient multiplier 214 _m .

Here, the coefficient updating unit 216 sequentially calculates tap coefficients K ₀ (T) to K _2N (T) according to the following equations (3) to (5).
ERR (T) = ([Y (T)] ² + [Y (T−τ)] ² ) ^1/2 −V _TH (3)
K _m (T−τ) = K _m (T) −α · ERR (T) · P _m (T) (4)
_Pm (T) = _Xm (T) .Y (T) + _Xm (T-.tau.). Y (T-.tau.) (5)
Here, the value V _TH is a predetermined convergence value, and is predetermined by experiment, simulation, experience, or the like. The value α is a value for adjusting the convergence speed, and is predetermined by experiment, simulation, experience, or the like.

Next, the reproduction processing unit 150 will be described. As shown in FIG. 3, the reproduction processing unit 150 includes a detection unit 151 ₁ as a first detection unit, a detection unit 151 ₂ as a second detection unit, a weighting addition unit 152 as an addition unit, and a stereo And a demodulator 153.

The detector 151 ₁ receives the signal FLD sent from the adaptive filter unit 130. The detection unit 151 ₁ performs digital detection processing on the signal FLD by a predetermined method to generate a detection signal DTD ₁ that is a composite signal. The detection signal DTD ₁ generated in this way is sent to the weighting addition unit 152 and the control unit 190.

The detector 151 ₂ receives the signal DLD sent from the delay unit 140. Then, the detection unit 151 ₂ performs digital detection processing on the signal DLD by a predetermined method similar to that of the detection unit 151 ₁ to generate a detection signal DTD ₂ that is a composite signal. The detection signal DTD ₂ generated in this way is sent to the weighted addition unit 152 and the control unit 190.

Weighted addition unit 152 described above, the detection signal DTD ₁ sent from the detection unit 151 _1, and receives a detection signal DTD ₂ sent from the detection unit 151 _2. Then, the weighting addition unit 152 performs weighted addition of the detection signal DTD ₁ and the detection signal DTD _{2 according} to the following equation (6) using the weighting coefficients CF ₁ and CF ₂ sent from the control unit 190. The signal WAD is calculated.
WAD = CF ₁ · DTD ₁ + CF ₂ · DTD ₂ (6)
The signal WAD calculated in this way is sent to the stereo demodulator 153.

  The stereo demodulator 153 receives the signal WAD sent from the weighted adder 152. Then, stereo demodulation section 153 performs stereo demodulation processing including separation processing on signal WAD to generate signal DMD. The generated signal DMD is sent to the analog processing unit 160.

Next, the control unit 190 will be described. As shown in FIG. 4, the control unit 190 includes a level detection unit 221 as a first detection unit, an amplitude modulation (AM) component extraction unit 222 as a part of the second detection unit, and a second detection unit. And a level detector 223 as a part of the above. The control unit 190 includes BPF units 226 ₁ and 226 ₂ and level detection units 227 ₁ and 227 ₂ . Furthermore, the control unit 190 includes a processing control unit 229 as a determination unit.

  The level detection unit 221 receives the signal DLD sent from the delay unit 140. Then, the level detector 221 detects the level of the signal DLD. The detection result by the level detection unit 221 reflects the electric field strength of the broadcast wave of the desired station that has been selected. The detection result by the level detection unit 221 is sent to the processing control unit 229 as the reception signal level SLV.

  The AM component extraction unit 222 receives the signal DLD sent from the delay unit 140. Then, the AM component extraction unit 222 extracts the AM modulation component of the signal DLD. Such an AM modulation component is generated due to the influence of the multipath phenomenon. The extraction result by the AM component extraction unit 222 is sent to the level detection unit 223 as a signal MPD.

  The level detection unit 223 receives the signal MPD sent from the AM component extraction unit 222. Then, the level detection unit 223 detects the level of the signal MPD. The detection result by the level detection unit 223 reflects the degree of influence of multipath fading. The detection result by the level detection unit 223 is sent to the processing control unit 229 as a multipath level MPL.

The BPF unit 226 ₁ receives the detection signal DTD ₁ sent from the reproduction processing unit 150. Then, the BPF unit 226 ₁ allows a narrow band (bandwidth: ΔF) component having each of the predetermined frequencies F ₁ and F ₂ as center frequencies to pass therethrough. The signals PD ₁₁ and PD ₁₂ that have passed through the BPF unit 226 ₁ are sent to the level detection unit 227 ₁ .

BPF 226 ₂ above, receiving a detection signal DTD ₂ sent from the reproduction processing unit 150. Then, the BPF unit 226 ₂ passes a narrow band (bandwidth: ΔF) component having each of the predetermined frequencies F ₁ and F ₂ as the center frequency, like the BPF unit 226 ₁ described above. The signals PD ₂₁ and PD ₂₂ that have passed through the BPF unit 226 ₂ are sent to the level detection unit 227 ₂ .

The level detection unit 227 ₁ receives the signals PD ₁₁ and PD ₁₂ sent from the BPF unit 226 ₁ . Then, the level detector 227 ₁ detects the levels of the signals PD ₁₁ and PD ₁₂ . The detection result by the level detection unit 227 ₁ is sent to the processing control unit 229 as detection levels LV ₁₁ and LV ₁₂ .

The level detection unit 227 ₂ receives the signals PD ₂₁ and PD ₂₂ sent from the BPF unit 226 ₂ . Then, the level detector 227 ₂ detects the levels of the signals PD ₂₁ and PD ₂₂ . The detection result by the level detection unit 227 ₂ is sent to the processing control unit 229 as detection levels LV ₂₁ and LV ₂₂ .

Here, the configuration of the BPF unit 226 _j (j = 1, 2) and the level detection unit 227 _j will be described.

As shown in FIG. 5, the BPF unit 226 _j includes an individual BPF unit 226 _j1 and an individual BPF unit 226 _j2 . The individual BPF unit 226 _j1 passes a component of a bandwidth ΔF (hereinafter referred to as “first band”) having a predetermined frequency F ₁ as a center frequency in the detection signal DTD _j sent from the reproduction processing unit 150. The signal PD _j1 is sent to the level detector 227 _j . In addition, the individual BPF unit 226 _j2 includes a component of a bandwidth ΔF (hereinafter referred to as “second band”) having a predetermined frequency F ₂ as a center frequency in the detection signal DTD _j sent from the reproduction processing unit 150. Pass it and send it to the level detector 227 _j as a signal PD _j2 .

The characteristics of the individual BPF unit 226 _j1 are shown in FIG. The characteristics of the individual BPF unit 226 _j2 are shown in FIG.

As shown in FIG. 5, the level detection unit 227 _j includes an individual level detection unit 227 _j1 and an individual level detection unit 227 _j2 . The individual level detection unit 227 _j1 detects the level of the signal PD _j1 sent from the individual BPF unit 226 _j1 and sends it to the processing control unit 229 as the detection level LV _j1 . The individual level detection unit 227 _j2 detects the level of the signal PD _j2 sent from the individual BPF unit 226 _j2 and sends it to the processing control unit 229 as the detection level LV _j2 .

  Said process control part 229 implement | achieves the function of FM receiving apparatus 100 by performing various processes. The processing control unit 229 analyzes the operation input data IPD from the operation input unit 180. When the content of the operation input data IPD is channel selection designation, the control unit 190 generates a channel selection command CSL corresponding to the designated desired station and sends it to the RF processing unit 120. If the content of the operation input data IPD is a volume adjustment designation including a volume adjustment mode, the processing control unit 229 generates a volume adjustment command VLC corresponding to the specified volume adjustment mode, The data is sent to the processing unit 160 (see FIG. 4).

Further, the processing control unit 229 receives the signal level SLV, multipath level MPL, detection levels LV ₁₁ , LV ₁₂ , LV ₂₁ , and LV ₂₂ sent from the level detection units 221, 223, 227 ₁ , and 227 ₂ . Then, the processing control unit 229 determines the weight coefficients CF ₁ and CF ₂ based on these levels SLV, MPL, LV ₁₁ , LV ₁₂ , LV ₂₁ , and LV ₂₂ . The determined weight coefficients CF ₁ and CF ₂ are sent to the reproduction processing unit 150 (see FIG. 4). Details of the determination processing of the weighting factors CF ₁ and CF ₂ by the processing control unit 229 will be described later.

[Operation]
The operation of the FM receiver 100 configured as described above will be described mainly focusing on the weight coefficient calculation processing by the processing control unit 229.

  As a premise, it is assumed that a channel selection designation has already been input to the operation input unit 180 by the user, and a channel selection command CSL corresponding to the designated desired station has been sent to the RF processing unit 120. Further, it is assumed that a volume adjustment designation has already been input by the user to the operation input unit 180, and a volume adjustment command VLC corresponding to the designated volume adjustment mode has been sent to the analog processing unit 160 (FIG. 1).

  In this state, when a broadcast wave is received by the antenna 110, a reception signal RFS is transmitted from the antenna 110 to the RF processing unit 120. Then, in the RF processing unit 120, after the signal of the desired station to be selected is converted into a signal in the intermediate frequency band, AD conversion is performed. The result of this AD conversion is sent to the adaptive filter unit 130 and the delay unit 140 as an intermediate frequency signal IFD (see FIG. 1).

  The adaptive filter unit 130 that has received the intermediate frequency signal IFD performs the adaptive filtering process as described above. Then, the adaptive filter unit 130 sends the processing result of the adaptive filtering process to the reproduction processing unit 150 as a signal FLD (see FIG. 1).

  In addition, the delay unit 140 that has received the intermediate frequency signal IFD performs a delay process of a time Nτ that is a process delay time by the adaptive filtering process in the adaptive filter unit 130 on the intermediate frequency signal IFD. Then, the delay unit 140 sends the delay processing result as a signal DLD to the reproduction processing unit 150 and the control unit 190 (see FIG. 1).

In the reproduction processing unit 150, the detector 151 ₁ receives the signal FLD. Upon receiving the signal FLD, the detection unit 151 ₁ performs digital detection processing on the signal FLD by a predetermined method to generate a detection signal DTD ₁ . Then, the detection unit 151 ₁ sends the detection signal DTD ₁ to the weighting addition unit 152 and the control unit 190 (see FIG. 3).

In the reproduction processing unit 150, the detector 151 ₂ receives the signal DLD. Upon receiving the signal DLD, the detection unit 151 ₂ performs digital detection processing on the signal DLD by a predetermined method to generate a detection signal DTD ₂ . Then, the detection unit 151 ₂ sends the detection signal DTD ₂ to the weighted addition unit 152 and the control unit 190 (see FIG. 3).

In the control unit 190, the BPF unit 226 ₁ receives the detection signal DTD ₁ transmitted from the detection unit 151 ₁ . Then, BPF unit 226 ₁ is selectively passed through the components of the first and second bands described above in the detection signal DTD _1, as the signal PD _11, PD _12, and sends to the level detection unit 227 _1. Subsequently, the level detection unit 227 ₁ detects the levels of the signals PD ₁₁ and PD ₁₂ and sends them to the processing control unit 229 as detection levels LV ₁₁ and LV ₁₂ (see FIG. 4).

Further, the control unit 190, BPF 226 ₂ receives the detection signal DTD ₂ sent from the detection unit 151 _2. Then, BPF unit 226 _2, selectively passed through the components of the first and second bands described above in the detection signal DTD _2, as a signal PD _21, PD _22, and sends to the level detecting unit 227 _2. Subsequently, the level detection unit 227 ₂ detects the levels of the signals PD ₂₁ and PD ₂₂ and sends them to the processing control unit 229 as detection levels LV ₂₁ and LV ₂₂ (see FIG. 4).

  Further, in the control unit 190, in parallel with the level detection described above, the level detection unit 221 detects the level of the signal DLD sent from the delay unit 140 and sends it to the processing control unit 229 as the reception signal level SLV. In the control unit 190, the AM component extraction unit 222 extracts the AM modulation component of the signal DLD sent from the delay unit 140. Then, the level detection unit 223 detects the level of the signal MPD and sends it to the processing control unit 229 as a multipath level MPL (see FIG. 4).

Based on the levels SLV, MPL, LV ₁₁ , LV ₁₂ , LV ₂₁ , and LV ₂₂ detected in this way, the processing control unit 229 determines the weight coefficients CF ₁ and CF ₂ . In such determination, as shown in FIG. 8, first, in step S11, the processing control unit 229 acquires the detected levels SLV, MPL, LV ₁₁ , LV ₁₂ , LV ₂₁ , and LV ₂₂ . Subsequently, in step S12, the processing control unit 229 calculates the level ratios R ₁ and R ₂ by the following equations (7) and (8).
R ₁ = LV ₁₁ / LV ₂₁ (7)
R ₂ = LV ₁₂ / LV ₂₂ (8)

Next, in step S13, the processing control unit 229 uses the level ratios R ₁ and R ₂ , the received signal level SLV, and the multipath level MPL to correspond to components other than the desired station broadcast wave in the intermediate frequency signal IFD, That is, the interference signal mixing rate β is estimated. Here, the mixing rate β is estimated to be any value in the range of 0 to 1. For example, if both values of the level ratios R ₁ and R ₂ are values that can be said to include no interference signal when the received signal level SLV and the multipath level MPL are considered, the processing control unit 229 The mixing rate β is estimated to be “0”. In addition, when both values of the level ratios R ₁ and R ₂ take the received signal level SLV and the multipath level MPL into consideration, the applied filter unit 130 is not a signal component corresponding to the broadcast wave of the desired station, but an interference signal. When it can be said that the operation following the component is performed, the mixing rate β is estimated to be “greater than ½”.

Next, in step S14, the processing control unit 229 determines weighting factors CF ₁ and CF ₂ by the following equations (9) to (12) based on the estimated mixing rate β.
CF ₁ = 1−β (when β <1/2) (9)
CF ₁ = 0 (when β ≧ 1/2) (10)
CF ₂ = β (when β <1/2) (11)
CF ₂ = 1 (when β ≧ 1/2) (12)

FIG. 9 shows how the weighting factors CF ₁ and CF ₂ change according to the change in the mixing rate β. In FIG. 9, the change of the weighting factor CF ₁ is indicated by a thick solid line, and the change of the weighting factor CF ₂ is indicated by a thick broken line. This notation is the same in FIGS. 10 to 12 described later.

When the weighting factors CF ₁ and CF ₂ are determined as described above, the processing control unit 229 sends the determined weighting factors CF ₁ and CF ₂ to the reproduction processing unit 150 in step S15, whereby the weighting factors CF ₂ and CF ₂ are determined. CF ₁ and CF ₂ are designated to the weighted addition unit 152 in the reproduction processing unit 150. Then, the process returns to step S11.

Thereafter, the processes of steps S11 to S15 are repeated. Each time the weighting factors CF ₁ and CF ₂ are newly determined, the weighting factors CF ₁ and CF ₂ are designated to the weighting addition unit 152.

More weighting factor is determined as CF _1, CF ₂ weighted addition unit 152 which has received the according the above-described (6), a detection signal DTD ₁ sent from the detection unit 151 _1, the detection unit 151 ₂ The weighted addition is performed with the detection signal DTD ₂ sent from. Then, the weighting addition unit 152 sends the addition result as a signal WAD to the stereo demodulation unit 153 (see FIG. 3).

  Upon receiving the signal WAD, the stereo demodulation unit 153 performs stereo demodulation processing including separation processing on the signal WAD. Then, stereo demodulation section 153 sends the result of stereo demodulation processing to analog processing unit 160 as signal DMD (see FIG. 3).

  In the analog processing unit 160 that has received the signal DMD from the reproduction processing unit 150, the DA conversion unit, the volume adjustment unit, and the power amplification unit sequentially perform processing to generate an output audio signal AOS and send it to the speaker unit 170 ( (See FIG. 1). Then, the speaker unit 170 reproduces and outputs sound in accordance with the output sound signal AOS from the analog processing unit 160.

As described above, in this embodiment, the detection signal DTD ₁ obtained by detecting the adaptive filtering processing result for the intermediate frequency signal IFD by the adaptive filter unit 130 and the detection signal obtained by detecting the delay processing result for the intermediate frequency signal IFD by the delay unit 140 are detected. The control unit 190 compares the signal DTD ₂ with it. Subsequently, the control unit 190 estimates the mixing ratio of the interference signal in the intermediate frequency signal IFD. Then, the control unit 190, based on the estimated mixing ratio, the weighting factor CF ₁ for the detection signal DTD _1, and calculates the weight coefficient CF ₂ against detection signal DTD _2. Here, when the control unit 190 determines that the adaptive filter unit 130 is performing an operation following the component of the interference signal instead of the signal component corresponding to the broadcast wave of the desired station, the control unit 190 sets the weighting factor CF ₁ . “0”.

According to the weighting factors CF ₁ and CF ₂ thus determined, the weighting addition unit 152 weights and adds the detection signal DTD ₁ and the detection signal DTD ₂ . In the weighted addition result, the smaller the mixing rate β, the higher the ratio of the detection result of the signal FLD that is the result of the adaptive filtering process, and the higher the mixing rate β, the higher the ratio of the detection result of the signal DLD including the interference signal. Become. When the mixing rate β is ½ or more, the weighted addition result is only the detection result of the signal DLD.

  By performing such weighted addition, a signal to be subjected to stereo demodulation processing is generated. A sound corresponding to the generated signal is output from the speaker unit 170. Therefore, according to the present embodiment, the listener feels uncomfortable due to the occurrence of a phenomenon such as suddenly switching to the sound corresponding to the broadcast of the adjacent station, even though the desired station is selected. It is possible to achieve harmony between the suppression of occurrence and the output of high-quality reproduced audio.

  Further, in the present embodiment, when the interference signal mixing rate is estimated, the signal level of the intermediate frequency signal IFD and the influence of the multipath phenomenon on the intermediate frequency signal IFD are taken into consideration. For this reason, it is possible to reasonably estimate the interference signal mixing rate.

[Modification of Embodiment]
The present invention is not limited to the above-described embodiment, and various modifications are possible.

For example, in the above-described embodiment, the level of the intermediate frequency signal IFD is detected and taken into account when estimating the mixing ratio of the interference signal into the intermediate frequency signal IFD. On the other hand, if automatic gain control (AGC) is performed on the intermediate frequency signal IFD, detection of the level of the intermediate frequency signal IFD can be omitted in estimating the mixing rate. In this case, when there is no interfering signal and no multipath phenomenon occurs, both values of the level ratios R ₁ and R ₂ are “approximately 1”.

In the above embodiment, the levels of the two band components of the first and second bands are compared for the detection signals DTD ₁ and DTD ₂ , but the number of band of the component level to be compared is one. There may be three or more. In addition, the estimation accuracy of the mixing rate β increases as the number of bands of the component level to be compared increases.

In the above embodiment, the levels of the two band components of the first and second bands are compared for the detection signals DTD ₁ and DTD ₂ , but each component has a predetermined level in a predetermined length period. You may make it compare the frequency | count exceeding.

  In the above embodiment, the signal corresponding to the broadcast wave received by the same antenna is supplied to the adaptive filter unit and the delay unit. However, the signal supplied to the adaptive filter unit, the signal supplied to the delay unit, May be signals corresponding to broadcast waves received by different antennas.

In the above embodiment, the weight coefficients CF ₁ and CF ₂ are determined by the above-described equations (9) to (12), but are determined by the following equations (13) to (16). Also good.
CF ₁ = 1-2β (when β <1/2) (13)
CF ₁ = 0 (when β ≧ 1/2) (14)
CF ₂ = 2β (when β <1/2) (15)
CF ₂ = 1 (when β ≧ 1/2) (16)
FIG. 10 shows how the weighting factors CF ₁ and CF ₂ change according to the change in the mixing rate β in this case.

Further, in FIGS. 9 and 10 described above, in the range of 1/2 <β ≦ 1, the weight coefficients CF ₁ and CF ₂ change linearly with respect to the change in the mixing rate β. As shown in FIG. 12, it may be changed nonlinearly with respect to the change in the mixing rate β.

  In the above embodiment, the adaptive filter unit is configured as an IIR type filter, but may be configured as an FIR (Finite Impulse Response) type filter, or an IIR type filter and an FIR type filter may be intermediate. It is good also as a structure which can be switched according to the level detection result etc. of a frequency signal.

  In the above embodiment, the adaptive filtering processing algorithm adopted by the adaptive filter unit is CMA. However, other adaptive filtering processing algorithms may be adopted.

  In the above embodiment, the present invention is applied to the FM receiver. However, the present invention can also be applied to other types of broadcast receivers.

  The adaptive filter unit 130, the regeneration processing unit 150, and the control unit 190 in the above-described embodiment are configured as a computer as a calculation unit including a central processing unit (CPU), a DSP (Digital Signal Processor), and the like. Then, a part or all of the processing in the above embodiment may be executed by executing a program prepared in advance on the computer. This program is recorded on a computer-readable recording medium such as a hard disk, CD-ROM, or DVD, and is read from the recording medium and executed by the computer. The program may be acquired in a form recorded on a portable recording medium such as a CD-ROM or DVD, or may be acquired in a form distributed via a network such as the Internet. Also good.

100 ... FM receiver (broadcast receiver)
130 ... Adaptive filter unit (adaptive filter means)
140 ... delay unit (delay means)
151 ₁ ... Detection section (first detection means)
151 ₂ ... Detection section (second detection means)
152 ... Weighting addition part (addition means)
221... Level detection unit (first detection means)
222... AM component extraction unit (part of second detection means)
223... Level detection unit (part of second detection means)
229 ... Processing control unit (determining means)

Claims (8)

A broadcast receiving device mounted on a mobile body,
Adaptive filter means for adaptively performing filtering on the intermediate frequency signal of the broadcast wave;
First detection means for detecting a signal subjected to filtering processing by the adaptive filter means;
Delay means for delaying the intermediate frequency signal of the broadcast wave by a processing delay time by the adaptive filter means;
Second detection means for detecting a signal delayed by the delay means;
Adding means for weighting and adding the first detection signal obtained by the first detection means and the second detection signal obtained by the second detection means;
The first detection signal and the second detection signal are compared, and based on the result of the comparison, the weighting coefficients of the first detection signal and the second detection signal at the time of addition by the adding means are determined. Determining means;
A broadcast receiving apparatus comprising:   2. The broadcast according to claim 1, wherein the determination unit compares a signal level of a predetermined frequency band in the first detection signal with a signal level of the predetermined frequency band in the second detection signal. Receiver device.   The determining means compares the number of times that the signal level of the first detection signal exceeds a predetermined level with the number of times that the signal level of the second detection signal exceeds a predetermined level in a period of a predetermined length. The broadcast receiving apparatus according to claim 1.   The determination means increases the ratio of the weighting factor of the first detection signal to the weighting factor of the second detection signal as the mixing ratio of the interference signal in the intermediate frequency signal estimated from the comparison result is small. The broadcast receiving apparatus according to any one of claims 1 to 3, wherein First detection means for detecting electric field strength in the frequency band of the broadcast wave;
A second detection means for detecting a level of multipath noise in the frequency band of the broadcast wave;
5. The determination unit according to claim 1, wherein the determination unit determines the weighting factor in consideration of the detected electric field strength and the detected level of the multipath noise. Broadcast receiver. Adaptive filter means for adaptively filtering an intermediate frequency signal of a broadcast wave; first detection means for detecting a signal subjected to filtering processing by the adaptive filter means; and an intermediate frequency signal of the broadcast wave In a broadcast receiving apparatus mounted on a mobile body, a delay means for delaying the signal by a processing delay time by the adaptive filter means; and a second detection means for detecting a signal delayed by the delay means A broadcast signal processing method used,
A comparison step of comparing the first detection signal obtained by the first detection means with the second detection signal obtained by the second detection means;
A weight determination step for determining weighting factors of the first detection signal and the second detection signal based on the comparison result in the comparison step;
An addition step of performing weighted addition of the first detection signal and the second detection signal using the determined weighting factor;
A broadcast signal processing method comprising:   A broadcast signal processing program that causes a calculation means to execute the broadcast signal processing method according to claim 6.   8. A recording medium, wherein the broadcast signal processing program according to claim 7 is recorded so as to be readable by an arithmetic means.

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