JP4444784B2 - Receiving apparatus and receiving method - Google Patents

Description

  The present invention relates to a receiving apparatus and a receiving method, and particularly to reception suitable for reducing distortion that occurs when demodulating a sound range (especially LR region) when multipath noise is detected during FM reception. The present invention relates to an apparatus and a receiving method.

  Conventionally, in FM stereo reception, a stereo composite signal formed based on the received radio wave due to multipath noise generated by simultaneously receiving radio waves with different paths from the transmission antenna to the reception antenna at the reception antenna. The problem is that distortion occurs when demodulating the LR region in FIG.

  Therefore, in order to reduce such distortion, conventionally, when multipath noise is detected, the stereo separation (separation amount) is reduced by switching from stereo demodulation to monaural demodulation. It was.

  In this case, if multipath noise is no longer detected, the demodulation is returned from the monaural demodulation to the stereo demodulation.

  Furthermore, in the past, when switching between stereo and monaural as described above, it is possible to prevent the listener from feeling uncomfortable with the frequent switching between stereo and monaural when multipath noise is frequently detected. Therefore, a certain time constant is set when switching between stereo and monaural.

  As a result, for example, in a receiver that frequently detects multipath noise such as a mobile receiver, the degree of separation can be varied according to the time constant according to the amount of multipath noise detected. -The transition between monaural and smooth could be performed smoothly, and the uncomfortable feeling of sound quality could be reduced to some extent.

Japanese Patent No. 2983609 JP-A-9-186666 JP 2004-129162 A

  However, when controlling the degree of separation according to the amount of detection of multipath noise, if the amount of variation in the degree of separation is large, even if the time constant is set as described above, the sound quality is uncomfortable. It has been difficult to reduce sufficiently.

  Therefore, the present invention has been made in view of such points, and with a simple configuration, it is possible to sufficiently reduce the sense of incongruity that occurs during the transition between stereo and monaural while ensuring the necessary stereo area. Accordingly, an object of the present invention is to provide a receiving apparatus and a receiving method capable of demodulating a sound with a low sense of incongruity and good listening quality while reducing costs.

In order to achieve the above-described object, the receiving apparatus according to the present invention is characterized by a multipath noise detection circuit for detecting multipath noise mixed in a received signal, and a time constant for the detection signal of the multipath noise detection circuit. Multi-path noise by adjusting the transition time between stereo and monaural according to the time constant based on the detection signal to which the time constant is added by the time constant adding circuit. A stereo separation degree control according to the maximum separation degree control circuit that controls a maximum value of the stereo separation degree according to the detection signal, the maximum separation degree control When the detection signal to which the time constant is added by the time constant adding circuit has sustained a value exceeding a predetermined threshold for a predetermined time or more, the circuit determines the maximum value of the separation. Control is performed so as to maintain a predetermined reference value or shift to the reference value. On the other hand, the detection signal to which the time constant is added by the time constant adding circuit does not maintain a value exceeding the threshold for more than the predetermined time. In this case, the control is performed so as to maintain or shift to another reference value in which the maximum value of the degree of separation is lower than the reference value .

According to such a configuration, the maximum separation degree is controlled according to the multipath noise by controlling the maximum value of stereo separation according to the detection signal of the multipath noise by the maximum separation degree control circuit. It becomes possible to regulate within a suitable range. Furthermore, the maximum value of stereo separation can be controlled to a suitable value easily and with high accuracy in accordance with the detection amount and detection frequency of multipath noise.

  Further, the receiving apparatus according to the present invention is characterized in that the maximum separation control circuit has a phase correction circuit for correcting the phases of the pilot signal and the LR signal.

  And according to such a structure, it becomes possible to control the maximum value of the degree of separation reliably with a simple structure.

  Furthermore, the receiving apparatus according to the present invention is characterized in that the transition time between stereo and monaural is a return time from monaural to stereo.

  According to such a configuration, it is possible to regulate the fluctuation amount of the separation degree within a suitable range when returning from monaural to stereo according to the detection signal of the multipath noise by the maximum separation degree control circuit. It becomes.

Further, the characteristics of the reception method according to the present invention are to detect multipath noise mixed in the reception signal as a detection signal, add a time constant to the detection signal, and based on the detection signal to which the time constant is added, A reception method for controlling stereo separation according to multipath noise by adjusting a transition time between stereo and monaural according to the time constant, wherein the maximum value of the separation is set according to the detection signal. In this case, when the detection signal to which the time constant is added has maintained a value exceeding a predetermined threshold for a predetermined time or more, the maximum value of the separation degree is maintained at a predetermined reference value or Control is performed so as to shift to a reference value. On the other hand, when the detection signal to which the time constant is added does not maintain a value exceeding the threshold for the predetermined time or more, the maximum value of the separation degree is Standard value It lies in performing control so as to shift the other reference values below maintain or to the reference value.

According to such a method, by controlling the maximum value of stereo separation according to the detection signal of multipath noise, the variation amount of separation is regulated within a suitable range according to multipath noise. It becomes possible to do. Furthermore, it is possible to easily and accurately control the maximum value of stereo separation to a suitable value according to the detection amount and detection frequency of multipath noise.

  Furthermore, the reception method according to the present invention is characterized in that the maximum value of the degree of separation is controlled by correcting the phases of the pilot signal and the LR signal.

  According to such a method, the maximum value of the degree of separation can be reliably controlled by a simple method.

  In addition, the reception method according to the present invention is characterized in that the transition time between stereo and monaural is set as the return time from monaural to stereo.

  And according to such a method, it becomes possible to regulate the fluctuation amount of the separation degree within a suitable range when returning from monaural to stereo according to the detected amount of multipath noise.

  According to the receiving apparatus of the present invention, the maximum separation degree control circuit controls the maximum value of the stereo separation degree according to the detection signal of the multipath noise, so that the fluctuation amount of the separation degree is detected by the detection amount of the multipath noise. As a result of being able to be regulated within a suitable range according to the above, by ensuring a necessary stereo area with a simple configuration, it is possible to sufficiently reduce the sense of incongruity that occurs during the transition between stereo and monaural, While reducing the cost, it is possible to demodulate a sound with a low sense of incongruity and good listening quality.

  Further, according to the receiving apparatus according to the present invention, the maximum value of stereo separation can be controlled to a suitable value easily and with high accuracy according to the detection amount and detection frequency of multipath noise. It is possible to reliably and inexpensively demodulate a sound with a low sense of discomfort and good listening quality.

  Furthermore, according to the receiving apparatus according to the present invention, the maximum value of the degree of separation can be reliably controlled with a simple configuration, so that the cost can be further reduced.

  Furthermore, according to the receiving device of the present invention, the maximum separability control circuit regulates the variation amount of the separability when returning from monaural to stereo within a suitable range according to the detection signal of multipath noise. As a result, it is possible to sufficiently reduce the sense of incongruity that occurs when returning from monaural to stereo while ensuring the necessary stereo area with a simple configuration, thereby reducing costs and reducing discomfort. Sound with good listening quality can be demodulated.

  In addition, according to the reception method of the present invention, the maximum amount of stereo separation is controlled according to the detection result of multipath noise, so that the amount of change in separation is suitable for the detection amount of multipath noise. As a result of being able to regulate within a certain range, it is possible to reduce the cost by making it possible to sufficiently reduce the sense of incongruity that occurs during the transition between stereo and monaural while securing the necessary stereo area by a simple method. On the other hand, it is possible to demodulate a sound with a little sense of incongruity and good listening quality.

  Furthermore, according to the reception method of the present invention, the maximum value of stereo separation can be controlled to a suitable value easily and with high accuracy according to the detection amount and detection frequency of multipath noise. It is possible to reliably and inexpensively demodulate a sound with a low sense of discomfort and good listening quality.

  Furthermore, according to the receiving method of the present invention, the maximum value of the degree of separation can be reliably controlled by a simple method, so that the cost can be further reduced.

  In addition, according to the reception method of the present invention, it is possible to regulate the amount of change in the separation degree within a suitable range upon returning from monaural to stereo in accordance with the detection amount of multipath noise. With this method, it is possible to sufficiently reduce the sense of incongruity that occurs when returning from monaural to stereo while ensuring the necessary stereo area, thereby reducing the cost and reducing the sense of incongruity and listening quality. It can be demodulated.

  Hereinafter, a receiving apparatus according to the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the receiving apparatus 1 in this embodiment has a receiving antenna 2, and the receiving antenna 2 receives an FM transmission signal from a transmitting antenna (not shown). .

  A tuning circuit 3 is connected to the output side of the receiving antenna 2, and a signal component near a desired frequency to be received is emphasized and output in the tuning circuit 3.

  The receiving device 1 also has a local oscillation circuit 4. The local oscillation signal output from the local oscillation circuit 4 and the output signal from the tuning circuit 3 are mixed to generate an intermediate frequency signal. It has come to be.

  An intermediate frequency amplifier circuit 5 is connected to the output side of the tuning circuit 3 and the local oscillator circuit 4, and the intermediate frequency signal is input to the intermediate frequency amplifier circuit 5.

  The intermediate frequency amplifier circuit 5 amplifies and outputs the input intermediate frequency signal.

  An FM detection circuit 7 is connected to the output side of the intermediate frequency amplification circuit 5, and the signal output from the intermediate frequency amplification circuit 5 is input to the FM detection circuit 7.

  The FM detection circuit 7 extracts only the audio signal (stereo composite signal including the L + R signal and the LR signal) from the input signal and outputs it.

  On the output side of the FM detection circuit 7, a blend control circuit 8 that controls the mixing amount of the L + R signal and the LR signal in the audio signal detected by the FM detection circuit 7 performs phase correction of a maximum separability control circuit described later. They are connected via a circuit 12.

  The blend control circuit 8 outputs the audio signal after separating it into audio signals of the left and right channels according to the degree of separation.

  An L / R signal output circuit 9 is connected to the output side of the blend control circuit 8, and the left and right channel audio signals output from the blend control circuit 8 are input to the L / R signal output circuit 9. It has come to be.

  The L / R signal output circuit 9 outputs the input audio signals of the left and right channels at an appropriate level.

  The receiving apparatus 1 has a multipath noise detection circuit 10 on the output side of the FM detection circuit 7, and the multipath noise detection circuit 10 is an S meter in the audio signal extracted by the FM detection circuit 7. Multipath noise is detected based on the components and the like, and the detection result is output as a detection signal.

  A time constant addition circuit 11 is connected to the output side of the multipath noise detection circuit 10 and the input side of the blend control circuit 8. The time constant addition circuit 11 is connected to the detection of the multipath noise detection circuit 10. A signal is input.

  The time constant adding circuit 11 adds a time constant to the input detection signal and outputs a signal with the time constant added to the blend control circuit 8.

  Thereby, the return time from monaural to stereo or the transition time from stereo to monaural can be adjusted according to the time constant.

  Furthermore, the receiving apparatus 1 in this embodiment includes a maximum separability control circuit that controls the maximum value of stereo separability according to the detection signal.

  That is, a phase correction circuit 12 constituting a part of the maximum separability control circuit is connected between the output side of the FM detection circuit 7 and the input side of the blend control circuit 8. The audio signal output from the FM detection circuit 7 is input.

  A microcomputer 13 that constitutes a maximum separation degree control circuit together with the phase correction circuit 12 is connected between the output side of the multipath noise detection circuit 10 and the time constant addition circuit 11 and the input side of the phase correction circuit 12. Yes.

  The microcomputer 13 receives a detection signal from the multipath noise detection circuit 10 and a signal output from the time constant addition circuit 11.

  The microcomputer 13 determines a control amount for the phase correction circuit 12 based on each input signal, and outputs a control signal corresponding to the determined control amount to the phase correction circuit 12.

  The phase correction circuit 12 is supplied with the audio signal output from the FM detection circuit 7 and the control signal output from the microcomputer 13.

  Then, the phase correction circuit 12 corrects the phase of the pilot signal and the LR signal in the audio signal according to the control signal, so that the maximum value of the degree of separation corresponds to the detection signal of the multipath noise detection circuit 10. The value is controlled.

  Thereby, when adjusting the return time from monaural to stereo or the transition time from stereo to monaural according to the time constant, it is possible to restrict the variation range of the separation within a range not exceeding the maximum value.

  Therefore, according to the present embodiment, the variation amount of the separation degree can be reliably regulated within a suitable range according to the multipath noise by a simple method.

  Next, FIG. 2 and FIG. 3 show a more specific example of the present embodiment, and FIG. 2 shows that multipath noise is detected at a high frequency as shown in FIG. FIG. 3 shows an example of the transition of the maximum value of the separation when multipath noise is detected at a low frequency, as shown in FIG. ing.

  As shown in FIG. 2B and FIG. 3B, in this embodiment, the phase correction circuit 12 has a value that the detection signal to which the time constant is added by the time constant addition circuit 11 exceeds a predetermined threshold value. When it is maintained for a predetermined time (5 sec in FIGS. 2B and 3C) or longer, the separation return mode shown in FIGS. 2C and 3C is maintained or is changed to the separation return mode. It is supposed to migrate.

  In the separation return mode, the phase correction circuit 12 has a maximum value of separation (Max. Separation in FIGS. 2C and 3C) as shown in FIGS. 2C and 3C. Control is performed so that the high-separation-side reference value is maintained or shifted to the high-separation-side reference value.

  Further, as shown in FIG. 2B, the phase correction circuit 12 determines that the detection signal to which the time constant is added by the time constant adding circuit 11 exceeds a predetermined threshold value for a predetermined time (5 sec in FIG. 2). When the above is not continued, the low separation mode shown in FIG. 2C is maintained or shifted to the low separation mode.

  In the low separation mode, the phase correction circuit 12 maintains the low resolution side reference value in which the maximum value of the resolution is a reference value lower than the high resolution side reference value or the low resolution side reference value. Control is performed so as to shift to.

  The microcomputer 13 can determine whether the detection signal to which the time constant has been added has exceeded a predetermined threshold and whether the predetermined threshold has been maintained for a predetermined time.

  As a result, as shown in FIG. 4, the maximum value of stereo separation can be controlled to a suitable value easily and with high accuracy in accordance with the detection amount and detection frequency of multipath noise.

  For the predetermined threshold, the predetermined time, the low resolution side reference value, and the high resolution side reference value, desired values can be selected according to the concept.

  For example, the predetermined threshold may be 25 dB, the predetermined time may be 5 seconds as described above, the low resolution side reference value may be 25 dB, and the high resolution side reference value may be 40 dB.

  In addition, the transition speed of the maximum degree of separation from the low resolution side reference value to the high resolution side reference value and the transition speed of the maximum degree of separation from the high resolution side reference value to the low resolution side reference value Also, a desired value can be selected according to the concept.

  For example, the maximum separation speed from the high resolution side reference value to the low resolution side reference value is set to 2 dB / 200 msec, and the maximum separation degree from the low resolution side reference value to the high resolution side reference value is set. The value transition speed may be 2 dB / 2 sec.

  The phase correction circuit 12 is configured to output the audio signal after controlling the maximum value of the separation degree to the blend control circuit 8, whereby the variation amount of the separation degree is in a suitable range according to the multipath noise. The degree of stereo separation is controlled so as to be regulated within.

  Next, an embodiment of a reception method according to the present invention will be described with reference to FIGS.

  Note that the receiving method in the present embodiment can be executed using the above-described receiving apparatus.

  That is, in the present embodiment, first, in step 1 (ST1) of FIG. 5, the multipath noise detection circuit 10 detects the value of the multipath noise every certain time (for example, 10 msec).

  Next, in step 2 (ST2), the microcomputer 13 determines whether or not the detected amount of multipath noise exceeds a predetermined threshold value. If the threshold value is exceeded, the microcomputer 13 proceeds to step 3 (ST3), and below the threshold value. In the case of, the process ends.

  The determination by the microcomputer 13 at this time may be made based on a detection signal output directly from the multipath noise detection circuit 10 to the microcomputer 13, or a time constant is added by the time constant adding circuit 11. The detection may be performed based on the detected signal.

  Next, in step 3 (ST3), the microcomputer 13 determines whether or not the detection signal to which the time constant is added has maintained a value exceeding the threshold value for a predetermined time (for example, 5 seconds) or longer. If not, the process proceeds to step 4 (ST4), and if not continued, the process proceeds to step 5 (ST5).

  In step 4 (ST4), the mode shifts to the separation return mode shown in FIG. 6, while in step 5 (ST5), the mode shifts to the low separation mode shown in FIG.

  Next, in step 4 (ST4) in FIG. 5, when shifting to the separation return mode, first, in step 11 (ST11) in FIG. 6, when the separation return mode is started, in the subsequent step 12 (ST12), It is determined whether or not the current maximum value of the separation degree is the high separation side reference value (for example, 40 dB).

  In step 12 (ST12), if the current maximum value of the separation is the high-separation-side reference value, the process is ended and the maximum value of the separation is maintained as it is as the high-separation-side reference value. If the high-separation-side reference value is not satisfied, the process proceeds to step 13 (ST13).

  Next, in step 13 (ST13), control is performed to increase the maximum value of the separation to the high-separation-side reference value under the control of the phase correction circuit 12, and then the process ends.

  On the other hand, in the case of shifting to the low separation mode in step 5 (ST5) in FIG. 5, first, in step 21 (ST21) in FIG. 7, when the low separation mode is started, in the subsequent step 22 (ST22), the current It is determined whether or not the maximum value of the degree of separation exceeds a low-separation-side reference value (for example, 25 dB).

  In step 22 (ST22), if the current maximum value of the separation degree exceeds the low separation degree side reference value, the process proceeds to step 23 (ST23). Maintain the maximum value of.

  Next, in step 23 (ST23), control is performed by the phase correction circuit 12 to attenuate the maximum separation value to the low separation side reference value, and then the process ends.

  Therefore, according to the present embodiment, the maximum separation degree control circuit configured by the microcomputer 13 and the phase correction circuit 12 controls the maximum value of the stereo separation degree according to the detection signal of multipath noise. Can be regulated within a suitable range according to the multipath noise.

  As a result, with a simple configuration, it is possible to sufficiently reduce the sense of incongruity that occurs during the transition between stereo and monaural while securing the necessary stereo area, reducing costs and reducing the sense of incongruity and improving the listening quality. Sound can be demodulated.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible as needed.

The block diagram which shows embodiment of the receiver which concerns on this invention In the embodiment of the receiving apparatus according to the present invention, a graph showing a detection signal of high-frequency multipath noise, a signal with a time constant added to the detection signal, and a displacement of the maximum value of the separation at that time In the embodiment of the receiving apparatus according to the present invention, a low frequency multipath noise detection signal, a signal with a time constant added to the detection signal, and a displacement of the maximum value of the separation at that time The graph which shows the regulation state of the variation | change_quantity of a separation degree in embodiment of the receiver which concerns on this invention The flowchart which shows embodiment of the receiving method which concerns on this invention FIG. 5 is a flowchart showing a process of increasing the maximum value of separation as the subsequent process of FIG. 5 in the embodiment of the reception method according to the present invention. FIG. 5 is a flowchart illustrating a process for attenuating the maximum value of separation as the subsequent process of FIG. 5 in the embodiment of the reception method according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Receiver 10 Multipath noise detection circuit 11 Time constant addition circuit 12 Phase correction circuit 13 Microcomputer

Claims (6)

A multipath noise detection circuit for detecting multipath noise mixed in the received signal; and a time constant addition circuit for adding a time constant to the detection signal of the multipath noise detection circuit. This is a receiver capable of controlling stereo separation according to multipath noise by adjusting the transition time between stereo and monaural according to the time constant based on a detection signal to which a constant is added. And
A maximum separation degree control circuit for controlling the maximum value of the stereo separation degree according to the detection signal ;
When the detection signal to which the time constant is added by the time constant adding circuit keeps a value exceeding a predetermined threshold for a predetermined time or longer, the maximum separability control circuit determines that the maximum value of the separability is a predetermined value. When the control is performed so that the reference value is maintained or shifted to the reference value, and the detection signal to which the time constant is added by the time constant adding circuit does not maintain the value exceeding the threshold for the predetermined time or more. In the receiving apparatus , control is performed so as to maintain or shift to another reference value in which the maximum value of the degree of separation is lower than the reference value . The maximum separation control circuit, receiving apparatus according to claim 1, characterized in that it comprises a phase correction circuit for correcting the phases of the pilot signal and the L-R signal. The Stereo - transition time between monaural reception apparatus according to claim 1 or claim 2, characterized in that a recovery time to a stereo from mono. Multipath noise mixed in the received signal is detected as a detection signal, a time constant is added to this detection signal, and the transition time between stereo and monaural is set to the time constant based on the detection signal to which this time constant is added. Therefore, by adjusting, a reception method for controlling the degree of stereo separation according to multipath noise,
The maximum value of the degree of separation is controlled according to the detection signal, and when the detection signal to which the time constant is added maintains a value exceeding a predetermined threshold for a predetermined time or more, the degree of separation is determined. The control is performed so that the maximum value of the signal maintains the predetermined reference value or shifts to the reference value. On the other hand, the detection signal to which the time constant is added does not maintain the value exceeding the threshold for the predetermined time or longer. In this case, the receiving method is characterized in that control is performed so as to maintain or shift to another reference value in which the maximum value of the degree of separation is lower than the reference value . 5. The reception method according to claim 4 , wherein the maximum value of the degree of separation is controlled by correcting phases of a pilot signal and an LR signal. The stereo - the transition time between monaural The receiving method according to claim 4 or claim 5, characterized in that the return time to a stereo from mono.

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