JP2009016978A - Receiver, and frequency scanning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To switch a frequency in receiving to another frequency during multipath removing operation. <P>SOLUTION: A receiver 1 includes: a plurality of intermediate frequency signal generation means 11, 12 which respectively generate intermediate frequency signals received by mutually different antennas 21; a multipath component removing means 15 for compounding a plurality of intermediate frequency signals and generating an intermediate frequency signal obtained by multipath component removing processing; and a control means 47 for switching signal reception to the reception of the intermediate frequency signal by either one of the intermediate frequency signal generation means 11, 12 during the reception of the intermediate frequency signal obtained by the multipath component removing processing and allowing the other intermediate frequency signal generation means 11 or 12 which is not used for reception to scan other frequencies different from the frequency in receiving. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a receiver and a frequency scanning method.

  Patent Document 1 discloses a receiver that has a multipath processing unit and performs a multipath removal operation when a multipath is detected.

JP 2006-109186 A (summary, detailed description of the invention, etc.)

  However, in the receiver of Patent Document 1, when the multipath removal operation is started, the frequencies of the two tuners are fixed to the reception frequency. Therefore, there is no empty tuner in the receiver, and the receiver cannot scan other frequencies with the empty tuner.

  For example, the receiver cannot scan other frequencies until the reception state of at least one of the two tuners becomes good at the reception frequency and the multipath removal operation is released.

  As a result, once the multipath removal operation is started, even if there is a receiver capable of good reception at a frequency other than the frequency being received, the receiver of Patent Document 1 sets the reception frequency to the good frequency. It becomes impossible to switch to.

  It is an object of the present invention to obtain a receiver and a frequency scanning method capable of switching to a frequency other than the frequency being received during a multipath removal operation.

  In the receiver according to the present invention, a plurality of intermediate frequency signal generating means for generating intermediate frequency signals based on reception by different antennas and a plurality of intermediate frequency signals are combined to perform multipath component removal processing. During reception using the multipath component removing means for generating the intermediate frequency signal and the intermediate frequency signal subjected to the removal processing of the multipath component, switching to reception by the intermediate frequency signal of any of the intermediate frequency signal generating means is used for reception. Control means for scanning another frequency different from the frequency being received by the remaining intermediate frequency signal generating means.

  The receiver according to the present invention has the following features in addition to the above-described configuration of the invention. That is, the control means switches the received frequency to the scanned frequency when another frequency having a better reception status than the frequency being received is scanned.

  The receiver according to the present invention has the following features in addition to the components of the above-described invention. That is, the receiver further subtracts a value indicating the reception status of each intermediate frequency signal generated by each intermediate frequency signal generation means from a value indicating the reception status of the intermediate frequency signal that has been subjected to the multipath component removal processing. Thus, there is a computing means for computing the operating rate of the multipath component removal function for each intermediate frequency signal by the multipath component removal means. Then, the control means selects and switches the one with the lowest operating rate of the multipath component removal function among the plurality of intermediate frequency signal generation means for reception.

  The receiver according to the present invention has the following features in addition to the components of the above-described invention. That is, the receiver further demodulates the plurality of intermediate frequency signals generated by the plurality of intermediate frequency signal generation units and the intermediate frequency signal generated by the multipath component removal unit to generate a plurality of baseband signals. Subtract the value indicating the reception status of each baseband signal based on the processing of the intermediate frequency signal generation means from the value indicating the reception status of the baseband signal based on the processing of the baseband signal generation means and the multipath component removal means Thus, there is a computing means for computing the operating rate of the multipath component removal function for each intermediate frequency signal by the multipath component removal means. Then, the control means selects and switches the one with the lowest operating rate of the multipath component removal function among the plurality of intermediate frequency signal generation means for reception.

  The receiver according to the present invention has the following features in addition to the components of the above-described invention. That is, the receiver further demodulates one intermediate frequency signal selected from the plurality of intermediate frequency signals by the plurality of intermediate frequency signal generation means and the intermediate frequency signal by the multipath component removal means. Audio signal generating means for generating a received audio signal from the signal is provided. The control means has a high operation rate of the multipath component removal function for all of the plurality of intermediate frequency signals by the plurality of intermediate frequency signal generation means, and the reception status of the intermediate frequency signal by the multipath component removal means is good. In some cases, when the other frequency is scanned, the sound effect generation processing for mitigating the noise is performed by the sound signal generating means.

  The receiver according to the present invention has the following features in addition to the components of the above-described invention. That is, the control means stops scanning when the reception status of a signal received during scanning of another frequency deteriorates, and returns to reception by an intermediate frequency signal that has been subjected to multipath component removal processing.

  The receiver according to the present invention has the following features in addition to the components of the above-described invention. That is, the receiver further demodulates one intermediate frequency signal selected from the plurality of intermediate frequency signals by the plurality of intermediate frequency signal generation means and the intermediate frequency signal by the multipath component removal means. Audio signal generating means for generating a received audio signal from the signal is provided. The control means has a high operation rate of the multipath component removal function for all of the plurality of intermediate frequency signals by the plurality of intermediate frequency signal generation means, and the reception status of the intermediate frequency signal by the multipath component removal means is not good. In this case, when the other frequency is scanned, the output of the audio signal by the audio signal generating unit is muted and the other frequencies are scanned by the plurality of intermediate frequency signal generating units.

  The frequency scanning method according to the present invention is an intermediate frequency subjected to multipath component removal processing, which is a combination of a plurality of intermediate frequency signals generated by a plurality of intermediate frequency signal generation means based on reception by different antennas. This is a frequency scanning method during reception by a signal. The frequency scanning method includes a step of switching to reception by an intermediate frequency signal of one of a plurality of intermediate frequency signal generation means during reception by an intermediate frequency signal subjected to multipath component removal processing, and reception. When the remaining intermediate frequency signal generating means that is not used scans another frequency that is different from the frequency being received, and when another frequency that is better received than the frequency being received is scanned, the received frequency is scanned. Switching to the selected frequency.

  In the present invention, during the multipath elimination operation, switching to reception by the intermediate frequency signal of any of the intermediate frequency signal generation means, and other frequencies different from the frequency being received by the remaining intermediate frequency signal generation means not used for reception Therefore, it is possible to switch to a frequency other than the frequency being received during the multipath removal operation.

  Hereinafter, a receiver and a frequency scanning method according to an embodiment of the present invention will be described with reference to the drawings. The receiver will be described by taking an RDS (Radio Data System) radio broadcast receiver as an example. The frequency scanning method will be described as a part of the operation of the RDS radio broadcast receiver.

  FIG. 1 is a block diagram showing an RDS radio broadcast receiver 1 according to an embodiment of the present invention. The RDS radio broadcast receiver 1 is mounted on a moving body such as an automobile or carried by a moving person. The RDS radio broadcast receiver 1 employs a diversity system with two antennas and two tuners in order to realize optimal reception according to changes in the reception environment of radio waves accompanying movement.

  In the RDS radio broadcast, a broadcast audio signal and RDS data (digital data) are broadcast as broadcast radio waves in each broadcast frequency band (broadcast station). The RDS data includes information such as the name of the song being broadcast and the name of the artist being broadcast. Based on the RDS data, the RDS radio broadcast receiver 1 can display the name of the song being received, the artist name, etc. on the display device 48 or the like.

  The RDS radio broadcast receiver 1 has two IF sections, a first IF (intermediate frequency) section 11 and a second IF section 12, and two demodulation sections, a first demodulation section 13 and a second demodulation section 14. . In addition, the RDS radio broadcast receiver 1 includes an MP (multipath) noise removal circuit 15, an MP demodulator 16, an output selector 17, a DAC 18 (Digital to Analog Converter), a speaker 19, and the like. In the RDS radio broadcast receiver 1, the first IF unit 11 and the first demodulation unit 13 constitute a first tuner, and the second IF unit 12 and the second demodulation unit 14 constitute a second tuner. Composed.

  The two IF units of the first IF unit 11 and the second IF unit 12 serving as a plurality of intermediate frequency signal generating means include a receiving antenna 21, a front end circuit 22, an IF amplifier 23, and an AD converter 14 that receive RDS radio broadcast radio waves. , And an IF filter 25. The front end circuit 22 extracts a desired RDS radio broadcast wave (broadcast frequency band) received by the reception antenna 21 and performs frequency conversion to generate an IF signal. The IF amplifier 23 amplifies the generated IF signal. The AD converter 14 samples the amplified IF signal and converts it into IF data. The IF filter 25 extracts a signal component in a band corresponding to one broadcast frequency band by digital filtering processing for IF data. The first IF unit 11 and the second IF unit 12 output IF data signals (IF data signals) generated by the respective IF filters 25.

  Note that the receiving antenna 21 of the first IF unit 11 and the receiving antenna 21 of the second IF unit 12 are disposed at spatially different positions (for example, left and right side surfaces of the vehicle) or are spatially predetermined to each other. Or an angle of 90 degrees (for example, 90 degrees). By selecting one of the two reception antennas 21 according to the reception situation, the RDS radio broadcast receiver 1 in FIG. 1 realizes a spatial diversity system using the two IF units 11 and 12.

  The MP noise removal circuit 15 serving as a multipath component removal unit uses the IF data signal generated by the first IF unit 11 and the IF data signal generated by the second IF unit 12 to receive the received radio waves. The process which removes the multipath component contained in is performed.

  The multipath component occurs when one receiving antenna 21 simultaneously receives, for example, a broadcast radio wave (direct wave) output from a radio tower and a broadcast radio wave (reflected wave) reflected by a building or the like. It is a distortion component of the signal due to the reflected wave.

  The MP noise removal circuit 15 first assumes that the first IF unit 11 and the second IF unit 12 are receiving the same direct wave in phase, for example, and then converts the distortion components of those IF data signals. Extracted as a component of the reflected wave, and then subtracts the extracted distortion component (or an amplified version thereof) from one IF data signal. By such multipath component removal processing, the MP noise removal circuit 15 generates an IF data signal in which distortion components (reflected wave components) due to multipath are suppressed.

  The two demodulation units of the first demodulation unit 13 and the second demodulation unit 14 and the MP demodulation unit 16 include an FM demodulation circuit 31 and an FM processing unit 32. The FM demodulation circuit 31 functions as a baseband signal generation unit, and demodulates the IF data signal generated by the first IF unit 11, the second IF unit 12, or the MP noise removal circuit 15 to generate a baseband signal. Output. The FM processing unit 32 functions as a part of the audio signal generation unit, and performs stereo demodulation processing, stereo blend processing, f special adjustment processing, soft mute processing, mute processing, and the like on the demodulated baseband signal. The sound effect process is performed, and one sound data is output. Further, the selection and presence of these acoustic effect processes are controlled by the control unit. The first demodulator 13, the second demodulator 14, and the MP demodulator 16 output the generated audio data to the output selector 17.

  The output selector 17 selects one of the audio data input from the first demodulator 13, the audio data input from the second demodulator 14, and the audio data input from the MP demodulator 16, Output to the DAC 18.

  The DAC 18 as a part of the audio signal generating means converts the input audio data into an analog audio signal and outputs it.

  The speaker 19 is connected to the DAC 18. The speaker 19 is driven by an audio signal output from the DAC 18 and outputs a sound.

  With the above configuration, the RDS radio broadcast receiver 1 can receive the RDS radio broadcast radio wave and output the sound superimposed on the broadcast radio wave from the speaker 19. That is, the RDS radio broadcast receiver 1 includes the output selector 17, the audio data based on the broadcast data generated by the first IF unit 11 and the first demodulation unit 13 (first tuner), and the second IF unit 12. And audio data based on broadcast data generated by the second demodulator 14 (second tuner) and audio data based on broadcast data generated by the MP noise removal circuit 15 and the MP demodulator 16. One is selected, and sound based on the selected sound data is output.

  In the following, broadcast data generated by the FM demodulation circuit 31 of the first demodulation unit 13 based on the IF data signal generated by the first IF unit 11 is referred to as first broadcast data, and IF data generated by the second IF unit 12. Broadcast data generated by the FM demodulation circuit 31 of the second demodulator 14 based on the signal is referred to as second broadcast data, an IF data signal generated by the first IF unit 11 and an IF data signal generated by the second IF unit 12. The broadcast data generated by the FM demodulation circuit 31 of the MP demodulator 16 based on the above is called MP-removed broadcast data. Each broadcast data includes an audio signal, RDS data, and the like.

  In addition to this, the RDS radio broadcast receiver 1 includes a first reception status detection circuit 41, a first RDS decoder 42, a second reception status detection circuit 43, a second RDS decoder 44, an MP reception status detection circuit 45, An MPRDS decoder 46, a control unit 47, and the like are included.

  The first reception status detection circuit 41 detects the reception status of radio waves by the first IF unit 11 based on the first broadcast data. The second reception status detection circuit 43 detects the reception status of radio waves by the second IF unit 12 based on the second broadcast data. The MP reception status detection circuit 45 detects the reception status of radio waves by the second IF unit 12 based on the MP removal broadcast data. Each of these reception status detection circuits 41, 43, and 45 analyzes the target broadcast data, and detects, for example, reception field strength, multipath, adjacent signal, modulation degree, detuning, reception quality, and the like. Each reception status detection circuit 41, 43, 45 outputs each detection value to the control unit 47.

  The first RDS decoder 42 decodes the RDS data included in the first broadcast data. The second RDS decoder 44 decodes the RDS data included in the second broadcast data. The MPRDS decoder 46 decodes the RDS data included in the MP removal broadcast data. Also, each of these RDS decoders 42, 44, and 46 calculates a detection value of RDS decoding quality, a detection value of error correction, and the like when decoding RDS data. Each RDS decoder 42, 44, 46 outputs the decoded RDS data and various detection values to the control unit 47.

  The control unit 47 as a control unit and a calculation unit is realized by, for example, a CPU (Central Processing Unit) of a microcomputer (not shown) executing a program stored in a memory. Then, the control unit 47 controls reception of RDS radio broadcast waves by the RDS radio broadcast receiver 1. Specifically, for example, the control unit 47 determines the reception status of the RDS radio broadcast radio wave, and receives the front end circuit 22 and the IF filter 25 of the first IF unit 11, The front-end circuit 22 and IF filter 25 of the second IF unit 12, the FM processing unit 32, and the output selector 17 are controlled. In addition, the control unit 47 may control the DAC 18.

  Next, the operation of the RDS radio broadcast receiver 1 having the above configuration will be described. In the following explanation, mainly when one broadcast radio wave to start reception is selected or while one broadcast radio wave is being received, other than the selected broadcast frequency band for the broadcast to be received. An operation for scanning other frequencies will be described.

  FIG. 2 is a flowchart showing a flow of reception setting by the control unit 47. FIG. 3 is a flowchart showing a detailed flow of the check process in FIG.

  The control unit 47 repeatedly executes the reception setting process of FIG. 2 when, for example, a broadcast station (reception frequency) received by the RDS radio broadcast receiver 1 is selected or when a predetermined period has elapsed during reception. To do.

  In FIG. 2, first, the control unit 47 sets the front end circuit 22 and the IF filter 25 of the first IF unit 11 and the front end circuit 22 and the IF filter of the second IF unit 12 regardless of the reception status so far. 25, the reception frequency by the first IF unit 11 and the second IF unit 12 is set to the selected broadcast frequency (step ST1).

  Based on the setting of the selected broadcast frequency, the first reception status detection circuit 41, based on the first broadcast data, receives electric field strength, multipath, adjacent signal, modulation degree, detuning, reception quality at the selected broadcast frequency. And the detected values are output to the control unit 47. The second reception status detection circuit 43 detects the received electric field strength, multipath, adjacent signal, modulation degree, detuning, reception quality, etc. at the same broadcast frequency based on the second broadcast data, and detects them. The value is output to the control unit 47. Further, the MP reception status detection circuit 45 detects the received electric field strength, multipath, adjacent signal, modulation degree, detuning, reception quality, etc. at the same broadcast frequency based on the MP removal broadcast data, and detects these detected values. Is output to the control unit 47.

  The first RDS decoder 42 decodes the RDS data from the first broadcast data, calculates a detection value of RDS decoding quality, a detection value of error correction, and the like, and outputs them to the control unit 47. The second reception status detection circuit 43 decodes the RDS data from the second broadcast data, calculates a detection value of RDS decoding quality, a detection value of error correction, and the like, and outputs them to the control unit 47. The MP reception status detection circuit 45 decodes the RDS data from the MP-removed broadcast data, calculates a detection value for RDS decoding quality, a detection value for error correction, and the like, and outputs these to the control unit 47.

  In this 2-tuner reception (reception by the first IF unit 11 and the second IF unit 12) setting, the control unit 47 causes the output selector 17 to select the MP removal broadcast data and causes the DAC 18 to output the audio signal. . As a result, the sound of the broadcasting station being received is output from the speaker 19. If this operation is performed during reception, the sound of the broadcasting station being received continues to be output.

  After setting the selected broadcast frequency to be received by the two tuners, the control unit 47 sets the three broadcast data (first broadcast data, second broadcast) based on the detection value of the first reception status detection circuit 41 and the like. The reception status of the data and MP removal broadcast data), the operation rate of the MP noise removal circuit 15 and the like are calculated (step ST2).

  Specifically, for example, the control unit 47 uses the following Equation 1 to indicate a value indicating the reception status of the first broadcast data (first reception status value) and a value indicating the reception status of the second broadcast data (second A reception status value) and a value indicating the reception status of the MP removal broadcast data (MP removal reception status value) are calculated. The reception status value becomes larger as the reception environment becomes better, for example, and becomes smaller as the reception environment becomes worse. Note that the reception status value may be calculated based on a part of the detection values in Equation 1 below.

  Reception status value = (detection value of electric field strength × coefficient 1) + (detection value of multipath × coefficient 2) + (detection value of adjacent signal × coefficient 3) + (detection value of modulation factor × coefficient 4) + (decoding Tuning detection value × Coefficient 5) + (Reception quality detection value × Coefficient 6) + (RDS decoding quality detection value × Coefficient 7) + (Error correction detection value × Coefficient 8)

  Further, the control unit 47 calculates the operation rate of the MP noise removal circuit 15 for the first broadcast data using the following equation 2, and calculates the operation rate of the MP noise removal circuit 15 for the second broadcast data using the following equation 3. Calculate. The smaller the difference between the ratio of the multipath component in the first broadcast data or the second broadcast data and the ratio of the multipath component in the MP removal broadcast data, the smaller the value of the operation rate.

Operation rate of the MP noise removal circuit 15 for the first broadcast data = MP removal reception status value−first reception status value Equation 2
Operation rate of the MP noise removal circuit 15 for the second broadcast data = MP removal reception status value−second reception status value Equation 3

  After calculating the reception status of the three broadcast data and the two operating rates, the control unit 47 determines the status using the calculation results, and executes reception settings according to the determination results (step ST3).

  FIG. 4 is a table showing the relationship between the situation determination by the control unit 47 and the reception setting. Each column in FIG. 4 shows a set of determination contents and setting contents. Hereinafter, in FIG. 4, they are referred to as pattern 1, pattern 2, pattern 3, pattern 4, pattern 5, and pattern 6 in order from the left side. This table is stored in a memory (not shown) in the control unit 47 and is referred to by the control unit 47.

  Specifically, the control unit 47 first uses the operation rate of the MP noise removal circuit 15 for the first broadcast data, the operation rate of the MP noise removal circuit 15 for the second broadcast data, and the MP removal reception status value. Thus, one corresponding pattern is determined in the table of FIG. And the control part 47 performs reception setting with the setting content in an applicable pattern.

  For example, the operation rate of the MP noise removal circuit 15 for the first broadcast data is smaller (lower) than a predetermined value, the operation rate of the MP noise removal circuit 15 for the second broadcast data is smaller (lower) than the predetermined value, and the MP removal reception status When the value is larger than the predetermined value (good), the control unit 47 selects pattern 1 and sets for receiving two tuners (= reception of MP removal broadcast data) or any one of the tuner receptions. Execute the settings for

  Also, the operation rate of the MP noise removal circuit 15 for the first broadcast data is smaller (lower) than the predetermined value, the operation rate of the MP noise removal circuit 15 for the second broadcast data is smaller (lower) than the predetermined value, and the MP removal reception status When the value is smaller (bad) than the predetermined value, the control unit 47 selects the pattern 2 and sets for receiving two tuners (= reception of MP removal broadcast data) or any one of the tuner receptions. Execute the settings for

  Further, the operation rate of the MP noise removal circuit 15 for the first broadcast data is smaller (lower) than the predetermined value, the operation rate of the MP noise removal circuit 15 for the second broadcast data is larger (higher) than the predetermined value, and the MP removal reception status When the value is larger than the predetermined value (good), the control unit 47 selects the pattern 3 and performs setting for 2 tuner reception (= reception of MP removal broadcast data) or reception by the first broadcast data. Execute the settings for

  Also, the operation rate of the MP noise removal circuit 15 for the first broadcast data is larger (higher) than a predetermined value, the operation rate of the MP noise removal circuit 15 for the second broadcast data is smaller (lower) than a predetermined value, and the MP removal reception status When the value is larger than the predetermined value (good), the control unit 47 selects the pattern 4 and performs setting for 2 tuner reception (= reception of MP removal broadcast data) or reception by the second broadcast data. Execute the settings for

  Further, the operation rate of the MP noise removal circuit 15 for the first broadcast data is larger (higher) than a predetermined value, the operation rate of the MP noise removal circuit 15 for the second broadcast data is larger (higher) than the predetermined value, and the MP removal reception status When the value is larger than the predetermined value (good), the control unit 47 selects the pattern 5 and executes setting for 2 tuner reception (= reception of MP removal broadcast data).

  Further, the operation rate of the MP noise removal circuit 15 for the first broadcast data is larger (higher) than a predetermined value, the operation rate of the MP noise removal circuit 15 for the second broadcast data is larger (higher) than the predetermined value, and the MP removal reception status If the value is smaller (bad) than the predetermined value, the control unit 47 selects the pattern 6 and performs 2-tuner reception (= reception of MP removed broadcast data) according to the reception status of the MP removed broadcast data. Or setting for receiving with the first broadcast data or the second broadcast data.

  When the reception setting for the selected broadcast frequency is completed, the control unit 47 next determines whether or not to check other frequencies that broadcast the same content (step ST4). For example, when the control unit 47 receives information on other broadcast frequencies that broadcast the same content as RDS data or a predetermined time has passed since the last check, the control unit 47 determines to check other frequencies. Further, when it is not under these circumstances, the control unit 47 determines not to check other frequencies and ends the processing of FIG.

  When it is determined in step ST4 in FIG. 2 that the other frequencies are checked, the control unit 47 first determines the first IF unit 11 and the second IF unit 12 based on the previous situation determination as shown in FIG. While receiving at one of the IF units, it is determined whether or not the other IF unit can check (step ST11). In patterns 1 to 4 in FIG. 4, by using the IF unit with the lower operating rate for reception, it is possible to check with the other IF unit while receiving with one IF unit. Other frequencies can be checked without deteriorating the quality of the received sound.

  On the other hand, in patterns 5 and 6 in FIG. 4, both IF units (first IF unit 11 and second IF unit 12) are basically used to remove multipath components. Therefore, there is no vacant IF section, and other frequencies cannot be checked with the same reception setting. However, in the case of pattern 5, unlike the case of pattern 6, it is expected that the ratio of multipath components is not high. Therefore, in the case of pattern 5, it can be expected that a sound quality that can be viewed can be obtained by receiving only by the IF unit having a smaller operating rate, although the deterioration of the sound quality is inevitable.

  Therefore, in this embodiment, when the control unit 47 receives the patterns 1 to 5, the control unit 47 receives the signal from the first IF unit 11 and the second IF unit 12 while receiving the other IF unit. It is determined that the check is possible, and only in the case of pattern 6, it is determined that the check is not possible.

  When it is determined that the current setting status is according to patterns 1 to 5 and reception is performed by one IF unit of the first IF unit 11 and the second IF unit 12, and the other IF unit can perform a check. The control unit 47 selects one of the first IF unit 11 and the second IF unit 12 having the smaller operating rate for reception, and selects the remaining IF units for check. The control unit 47 causes the reception IF unit to receive the selected reception frequency, and causes the check IF unit to receive other frequencies to be checked (steps ST12 and ST13).

  As shown in FIG. 4, by this reception setting, the control unit 47 selects one of the first IF unit 11 and the second IF unit 12 for reception under the environment of pattern 1, and One of the first IF unit 11 and the second IF unit 12 is selected for reception under the environment, the first IF unit 11 is selected for reception under the pattern 3 environment, and the first IF unit 11 is selected for reception under the pattern 4 environment. The second IF unit 12 is selected for reception, and in the environment of pattern 5, one of the first IF unit 11 and the second IF unit 12 is selected for reception.

  If the other frequency to be checked is not specified by the RDS data or the like, the control unit 47 scans the frequency and obtains a program ID (the same frequency as the broadcast frequency being received, which is a frequency at which a predetermined reception sensitivity is obtained. The frequency at which the program identification number) is decoded may be received as another frequency to be checked.

  By the setting of steps ST12 and ST13, the check side of the first reception status detection circuit 41 and the second reception status detection circuit 43 sets the detection value such as the received electric field strength for the first broadcast data of the frequency to be checked. Output to the control unit 47. Also, the check-side one of the first RDS decoder 42 and the second RDS decoder 44 outputs a detection value such as RDS decoding quality for the first broadcast data of the frequency to be checked to the control unit 47. Then, the control unit 47 calculates the reception status value of the broadcast data on the check side based on the detection value on the check side. Further, the control unit 47 calculates the reception status value of the broadcast data on the reception side based on the detection value on the reception side (step ST14).

  After calculating the reception status value of the other frequency to be checked and the reception status value of the reception frequency, the control unit 47 executes reception frequency change processing according to those values. Specifically, the control unit 47 first determines whether or not the reception status value of the reception frequency is better than a predetermined reference value (whether or not it is larger) (step ST15). If the reception status value of the reception frequency is better (larger) than the predetermined reference value, the reception frequency by the IF unit on the reception side (one of the first IF unit 11 and the second IF unit 12) is changed. do not do.

  If the reception status value of the reception frequency is worse (smaller) than the predetermined reference value, the control unit 47 further compares the reception status value of this reception frequency with the reception status values of other frequencies (step ST16). If the reception status value of the other frequency is better (larger) than the reception status value of the reception frequency, the control unit 47 changes the reception frequency by the IF unit on the reception side to the checked other frequency (step ST17). ). Further, when the reception status value of other frequencies is worse (smaller) than the reception status value of the reception frequency, the control unit 47 does not change the reception frequency by the IF unit on the reception side.

  When the reception frequency change control according to the reception status values from steps ST15 to ST17 is completed, the control unit 47 determines whether or not all the frequencies scheduled to be checked have been checked (step ST18). For example, the control unit 47 determines whether or not the check has been completed based on whether or not other unprocessed broadcast frequencies remain in the RDS data, or based on whether or not scanning of all frequencies has been completed. It may be determined whether or not the check has been completed.

  If all the frequencies to be checked have not been checked, the control unit 47 sets the frequency of the check IF unit (the other IF unit in the first IF unit 11 and the second IF unit 12). Next, the frequency is switched to the frequency to be checked (step ST13), and the frequency switching process (steps ST13 to ST17) based on the reception status value comparison process similar to the first time is repeated.

  When all the frequencies scheduled to be checked have been checked, the control unit 47 sets the frequency finally set on the reception side as the reception frequency. If the setting on the receiving side has never been changed, the original receiving frequency is set on the receiving side.

  When the check process of FIG. 3 is completed, the control unit 47 returns the settings of the first IF unit 11 and the second IF unit 12 to the reception settings before the check, as shown in FIG. 2 (step ST6). However, the control unit 47 uses the frequency set on the reception side at the end of the check as the reception frequency. As a result, the RDS radio broadcast receiver 1 receives the same content as the selected broadcast frequency at the reception frequency that can be received under the best conditions.

  If it is determined that the pattern 5 is present before the check, the control unit 47 reduces noise as shown in the remarks column of FIG. 4 during the check processing period of one tuner from step ST12 to ST18. Is instructed to the FM processing unit 32. Examples of sound effect processing that can be used to reduce noise include soft mute processing, mute processing, stereo blend processing, and f special adjustment processing.

  By executing these acoustic effect processes, the FM processing unit 32 generates audio data with reduced noise, and the DAC 18 generates an audio signal from the audio data. That is, audio noise generated due to multipath noise or the like during reception of one tuner is suppressed. As a result, when the sound output based on the MP removal broadcast data is switched to the sound output based on the first broadcast data or the second broadcast data in the environment of the pattern 5, the deterioration of the sound quality after the switch is made inconspicuous. Can do. Noise increase during the check process can be prevented as much as possible.

  The current setting status is according to the pattern 6 in FIG. 4 and is received by one IF unit of the first IF unit 11 and the second IF unit 12 and checked by the other IF unit (1 tuner reception) 3, the control unit 47 instructs the FM processing unit 32 to mute as shown in FIG. 3 (step ST21), and then the operating rate in the first IF unit 11 or the second IF unit 12 is determined. The lower IF section receives the selected reception frequency, and the IF section with the higher operating rate receives other frequencies to be checked (steps ST22 and ST23). When the FM processing unit 32 mutes the output, the DAC 18 also mutes the output.

  Thereafter, the control unit 47 calculates the reception status value of the broadcast data on the check side based on the detection value on the check side, and calculates the reception status value of the broadcast data on the reception side based on the detection value on the reception side. (Step ST24).

  Moreover, the control part 47 performs the change process of the receiving frequency according to those reception status values. Specifically, the control unit 47 compares these reception status values (step ST25), and the IF unit (the first IF unit 11 and the second IF unit 12) on which the selected reception frequency is set. The frequency of one of the IF sections) is changed to a frequency with a better (larger) reception status value (step ST26).

  When the control for changing the reception frequency according to the reception status value is completed, the control unit 47 determines whether or not all the frequencies scheduled to be checked have been checked (step ST27). If all the frequencies to be checked have not been checked, the control unit 47 sets the frequency of the check IF unit (the other IF unit in the first IF unit 11 and the second IF unit 12). Next, the frequency is switched to the frequency to be checked (step ST23), and the frequency switching process (steps ST23 to ST26) based on the reception status value comparison process similar to the first time is repeated. In addition, when all the frequencies to be checked are checked, the control unit 47 selects a frequency finally set on the reception side as the reception frequency. Further, the control unit 47 releases the mute of the FM processing unit 32 (step ST28). When the FM processing unit 32 cancels the output mute, the DAC 18 also cancels the output mute.

  When the check processing by the two tuners in FIG. 3 is completed, the control unit 47 returns the settings of the first IF unit 11 and the second IF unit 12 to the reception settings before the check as shown in FIG. ST6). However, the control unit 47 uses the frequency set on the reception side at the end of the check as the reception frequency. As a result, the RDS radio broadcast receiver 1 receives the same content as the selected broadcast frequency at the reception frequency that can be received under the best conditions.

  As described above, according to this embodiment, the RDS radio broadcast receiver 1 changes the reception state to one tuner during reception (during two tuner reception) based on MP removal broadcast data subjected to multipath component removal processing. Switching to reception is performed, and further, another frequency is scanned using the first IF unit 11 or the second IF unit 12 which is vacated by this switching. The RDS radio broadcast receiver 1 scans the good frequency when there is something that can be satisfactorily received at a frequency other than the frequency being received during the reception of the two tuners. Can switch to frequency.

  That is, the RDS radio broadcast receiver 1 has a multipath noise removal function even in a radio wave situation where, for example, mild multipath noise continues to enter intermittently at the reception frequency, or in an area where electric field strength is high. Scanning other frequencies during reception based on IF data signals that have been processed to remove multipath components, even under radio wave conditions where strong multipath noise that cannot be completely removed continues to enter, The reception frequency can be switched to a better frequency. When there is a frequency better than the selected reception frequency, the RDS radio broadcast receiver 1 can smoothly switch the reception frequency without continuing reception with the selected reception frequency.

  In addition, the control unit 47 of this embodiment subtracts the first reception status value from the MP removal reception status value in order to perform a scan during reception (during 2 tuner reception) based on the MP removal broadcast data. The operating rate and the operating rate obtained by subtracting the second receiving status value from the MP removal receiving status value are calculated, and the one with the lower operating rate is selected for reception and switched.

  Therefore, the RDS radio broadcast receiver 1 accurately grasps the radio wave state and switches so that reception is performed by the IF unit having the smallest multipath component among the first IF unit 11 and the second IF unit 12. Therefore, even if the RDS radio broadcast receiver 1 switches to reception by one IF unit in order to scan other frequencies during the multipath removal operation (that is, it switches from two tuner reception to one tuner reception). Also, it is possible to minimize the degradation of the reception status due to the switching. The sound output from the RDS radio broadcast receiver 1 can be kept audible.

  In addition, as shown in pattern 5 in FIG. 4, the control unit 47 of this embodiment has a high operation rate of the multipath component removal function for all IF signals and a good reception status of the MP removal broadcast data. If so, the FM processing unit 32 performs acoustic effect processing for reducing noise.

  Accordingly, even when switching to reception by one IF unit during good reception in which the MP noise removal circuit 15 is functioning effectively (that is, even when switching from two tuner reception to one tuner reception), the switching is performed. It is possible to make the deterioration of sound quality due to multipath noise later inconspicuous. Noise increase during scanning can be prevented as much as possible. For this reason, the RDS radio broadcast receiver 1 continues to receive signals that do not cause discomfort to the user, for example, in radio wave conditions in which mild multipath noise continues to enter intermittently at the reception frequency. Can be switched to a better frequency.

  In addition, as shown in pattern 6 in FIG. 4, the control unit 47 of this embodiment has a high operation rate of the multipath component removal function for the first IF data signal and the second IF data signal, and MP removal. If the reception status of the broadcast data is not good, the output of the audio signal by the FM processing unit 32 is muted.

  Therefore, when there is a high possibility that the sound output from the RDS radio broadcast receiver 1 cannot be kept audible, the received sound being scanned is muted. Therefore, it is possible to prevent deterioration in sound quality due to switching to reception by one IF unit in a situation where good reception is not possible even based on MP removal broadcast data. Therefore, for example, the RDS radio broadcast receiver 1 is able to change the situation in a radio wave situation where strong multipath noise that cannot be completely removed by the multipath noise removal function continues to enter in an area where the electric field strength is high. It is possible to discriminate and scan other frequencies without causing discomfort to the user, and switch the reception frequency to a better frequency. During scanning, it can be determined that the user has not obtained tuning and the user is not switched to another broadcasting station.

  The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications and changes can be made without departing from the scope of the invention. is there.

  In the above embodiment, the detection circuit such as the first reception status detection circuit 41 detects the reception status based on the baseband signal demodulated by the demodulator such as the first demodulator. In addition to this, for example, the detection circuit detects the reception status based on the IF data signal generated by the first IF unit 11, the second IF unit 12, or the MP noise removal circuit 15 in the previous stage of the demodulator. It may be.

  That is, as in the embodiment, the control unit 47 as the calculation unit calculates each base based on the processing of the IF units 11 and 12 from the value indicating the reception status of the baseband signal based on the processing of the MP noise removal circuit 15. The operation rate of the multipath component removal function for each IF data signal by the MP noise removal circuit 15 may be calculated by subtracting a value indicating the reception status of the band signal, or in this modification example As described above, a value indicating the reception status of each IF data signal generated by each IF unit 11, 12 is obtained from the value indicating the reception status of the IF data signal subjected to the multipath component removal processing by the MP noise removal circuit 15. The operation rate of the multipath component removal function for each IF data signal by the MP noise removal circuit 15 may be calculated by subtraction.

  In the above embodiment, in the case of the pattern 5 in FIG. 4, the control unit 47 prevents the increase in noise during scanning as much as possible by causing the FM processing unit 32 to perform acoustic effect processing for reducing noise. In addition to this, for example, the controller 47 may prevent the increase in noise during scanning as much as possible by narrowing the bandwidth of the IF filter 25.

  In the RDS radio broadcast radio wave, the monaural audio component and the stereo audio component are carried by different frequency bands. Therefore, for example, by narrowing the bandwidth of the IF filter 25 so that only the monaural sound component is transmitted, high-frequency noise during scanning can be reduced.

  In the above embodiment, as shown in FIGS. 2 and 3, the control unit 47 does not finish the check process for other frequencies until the scan for all the frequencies is completed. In addition to this, for example, when the reception status value on the reception / playback side falls below a predetermined value during scanning of other frequencies, the control unit 47 stops the check process and returns to reception by MP-removed broadcast data or the like. Also good.

  In this modified example, even if the reception state may deteriorate during the check process, the deterioration of the reproduced sound is suppressed within a certain range. As a result, for example, in an environment where reception by MP removal broadcast data (two tuner reception) is supposed to be performed, reception by one IF unit in the first IF unit 11 and the second IF unit 12 (one tuner reception) The deterioration of the reproduction sound due to the switching can be suppressed to such an extent that the user does not feel uncomfortable and switches the receiving station (reception frequency).

  In the above embodiment, the control unit 47 calculates each reception status value based on the above Equation 1. In addition to this, for example, the control unit 47 uses the values indicating the reception status other than the electric field strength, the multipath, the adjacent signal, the modulation degree, the detuning, the reception quality, the RDS decoding quality, and the error correction. Alternatively, each reception status value may be calculated using only some of them.

  In particular, the MPRDS decoder 46 becomes unnecessary by using values indicating the reception status other than the detection values (RDS decoding quality and error correction) generated by the RDS decoder such as the MPRDS decoder 46. FIG. 5 is a block diagram showing a configuration of a modified example (No. 1) of the RDS radio broadcast receiver 1 that does not have the MPRDS decoder 46. In addition to this, the RDS radio broadcast receiver 1 of FIG. 5 has an IF selector 51 as compared with the RDS radio broadcast receiver 1 of FIG. The IF selector 51 in FIG. 5 stops the supply of the IF data signal generated by the first IF unit 11 to the first demodulation unit 13 or the second IF unit 12 generates based on an instruction from the control unit 47. The supply of the IF data signal to the second demodulator 14 is stopped, or the supply of the IF data signal generated by the MP noise removal circuit 15 to the MP demodulator 16 is stopped.

  FIG. 6 is a block diagram showing a configuration of a modified example (No. 2) of the RDS radio broadcast receiver 1. The RDS radio broadcast receiver 1 in FIG. 6 has an IF selector 61. The IF selector 61 in FIG. 6 is configured so that the IF data signal generated by the first IF unit 11, the IF data signal generated by the second IF unit 12, and the MP noise removal circuit 15 are based on an instruction from the control unit 47. Two of the generated IF data signals are selected and supplied to the first demodulator 13 and the second demodulator 14. In the RDS radio broadcast receiver 1 of FIG. 6 as well, the other IF units can scan other frequencies while receiving by one of the first IF unit 11 and the second IF unit 12. . Therefore, the RDS radio broadcast receiver 1 of FIG. 6 does not include the MP demodulator 16, the MP reception status detection circuit 45, and the MPRDS decoder 46.

  In the above embodiment, the control unit 47 uses each reception status value and each operation rate in each check process. In addition to this, for example, the control unit 47 may store the reception status value and the operating rate in association with the frequency in a memory (not shown) or the like and use it for the next check process. Such past reception status values and operating rates can be used, for example, to change the scan order of a plurality of frequencies. For example, the control unit 47 may scan a plurality of frequencies stored in the memory in the order in which better (larger) reception status values are obtained. By scanning a plurality of frequencies in this order, immediately after the start of the check, the frequency at which a better (larger) reception status value is obtained is set as the reception frequency, and reception (output) of the optimum frequency is started. You can expect that.

  In addition, for example, the control unit 47 associates position information by GPS (Global Positioning System) with the reception status value, operation rate, and frequency in association with each other and saves the information in a memory so that it can be referred to at the next scan. May be. Thus, the user can select a receivable area from a plurality of frequencies stored in the memory, and scan the selected plurality of frequencies in order from the one corresponding to the better one. it can.

  The above embodiment is an example of the RDS radio broadcast receiver 1 that employs a diversity system with two tuners. In addition to this, for example, the receiver is an RDS radio broadcast receiver that employs a diversity scheme with three or more tuners, an FM radio broadcast receiver that employs a diversity scheme with two or more tuners, and two or more tuners An AM (Amplitude Modulation) radio broadcast receiver that employs a diversity scheme according to the above may be used.

  Still further, for example, the receiver may be a receiver that receives a digital terrestrial broadcast that employs a diversity scheme using two or more tuners. This terrestrial digital broadcast receiver receives a video signal together with an audio signal by radio waves, and outputs video and audio.

  Even in these receivers, for example, when a broadcast having the same content can be received by a plurality of frequencies, the reception status value and the operation rate of each tuner are calculated, and one frequency is received by multipath removal (2 While the tuner is being received, it is possible to scan other frequencies of the same broadcast and switch to a frequency that allows better reception than the frequency being received.

  The present invention can be suitably used to realize frequency scanning during reception in an RDS radio broadcast receiver or the like.

FIG. 1 is a block diagram showing an RDS radio broadcast receiver according to an embodiment of the present invention. FIG. 2 is a flowchart showing reception settings by the control unit in FIG. FIG. 3 is a flowchart showing the check process in FIG. FIG. 4 is a table showing the relationship between situation determination and reception settings. FIG. 5 is a block diagram showing a configuration of a modified example (No. 1) of the RDS radio broadcast receiver. FIG. 6 is a block diagram showing a configuration of a modified example (No. 2) of the RDS radio broadcast receiver.

Explanation of symbols

1 RDS radio broadcast receiver (receiver)
11 First IF section (intermediate frequency signal generating means)
12 Second IF section (intermediate frequency signal generating means)
15 MP noise removal circuit (multipath component removal means)
18 DAC (part of audio signal generation means)
31 FM demodulation circuit (baseband signal generation means)
32 FM processing unit (part of audio signal generating means)
47 Control unit (control means, calculation means)

Claims (8)

A plurality of intermediate frequency signal generating means for generating intermediate frequency signals based on reception by different antennas;
A multipath component removing unit that synthesizes the plurality of intermediate frequency signals to generate an intermediate frequency signal that has been subjected to multipath component removal processing;
During reception by the intermediate frequency signal subjected to the removal processing of the multipath component, switching to reception by the intermediate frequency signal of any of the intermediate frequency signal generation means, by the remaining intermediate frequency signal generation means not used for reception, Control means for scanning another frequency different from the frequency being received;
A receiver comprising: The control means switches the received frequency to the scanned frequency when another frequency having a better reception status than the frequency being received is scanned.
The receiver according to claim 1. Subtracting a value indicating the reception status of each intermediate frequency signal generated by each of the intermediate frequency signal generation means from a value indicating the reception status of the intermediate frequency signal that has been subjected to the multipath component removal processing, Computation means for computing the operation rate of the multipath component removal function for each intermediate frequency signal by the path component removal means,
The control means selects and switches the one with the lowest operating rate of the multipath component removal function among the plurality of intermediate frequency signal generation means for reception,
The receiver according to claim 1 or 2. A plurality of baseband signal generating means for demodulating the plurality of intermediate frequency signals generated by the plurality of intermediate frequency signal generating means and the intermediate frequency signal generated by the multipath component removing means to generate a plurality of baseband signals When,
Subtracting a value indicating the reception status of each baseband signal based on the processing of each of the intermediate frequency signal generation means from a value indicating the reception status of the baseband signal based on the processing of the multipath component removal means, Computation means for computing the operation rate of the multipath component removal function for each intermediate frequency signal by the path component removal means,
The control means selects and switches the one with the lowest operating rate of the multipath component removal function among the plurality of intermediate frequency signal generation means for reception,
The receiver according to claim 1 or 2. From the baseband signal obtained by demodulating one intermediate frequency signal selected from the plurality of intermediate frequency signals by the plurality of intermediate frequency signal generating means and the intermediate frequency signal by the multipath component removing means, received speech Audio signal generating means for generating a signal;
The control unit has a high operation rate of the multipath component removal function for all of the plurality of intermediate frequency signals by the plurality of intermediate frequency signal generation units, and the reception status of the intermediate frequency signal by the multipath component removal unit is high. If it is good, when the other frequency is scanned, the sound signal generating means performs acoustic effect processing for mitigating noise,
The receiver according to claim 3 or 4.   The control means is characterized in that, when the reception status of a signal received during scanning of another frequency deteriorates, the scanning is stopped, and the control is returned to reception by the intermediate frequency signal subjected to the multipath component removal processing. Item 6. The receiver according to any one of Items 1 to 5. From the baseband signal obtained by demodulating one intermediate frequency signal selected from the plurality of intermediate frequency signals by the plurality of intermediate frequency signal generating means and the intermediate frequency signal by the multipath component removing means, received speech Audio signal generating means for generating a signal;
The control unit has a high operation rate of the multipath component removal function for all of the plurality of intermediate frequency signals by the plurality of intermediate frequency signal generation units, and the reception status of the intermediate frequency signal by the multipath component removal unit is high. If not good, when scanning other frequencies, mute the output of the audio signal by the audio signal generation means, and scan the other frequencies by the plurality of intermediate frequency signal generation means,
The receiver according to claim 3 or 4. A frequency scanning method during reception using an intermediate frequency signal subjected to multipath component removal processing, which is a combination of a plurality of intermediate frequency signals generated by a plurality of intermediate frequency signal generation means based on reception by different antennas. There,
A step of switching to reception by an intermediate frequency signal of one of the plurality of intermediate frequency signal generation means during reception by the intermediate frequency signal subjected to the removal processing of the multipath component;
Scanning other frequencies different from the frequency being received by the remaining intermediate frequency signal generating means not used for reception;
When another frequency with better reception than the frequency being received is scanned, switching the received frequency to the scanned frequency;
A frequency scanning method characterized by comprising:

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