JP4204027B2 - Broadcast receiving method and broadcast receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a broadcast receiving method and a broadcast receiver for receiving AM broadcast, FM broadcast, etc., and in particular, the output audio characteristics are kept good except for the influence of adjacent interfering radio waves mixed when receiving a broadcast of a desired station. The present invention relates to a broadcast receiving method and a broadcast receiver.
[0002]
[Prior art]
For example, in AM broadcasting, broadcasting stations are allocated at intervals of 9 kHz, and the intervals are relatively narrow. Therefore, if there is a high-power broadcasting station adjacent to the frequency of the station desired to receive, there is a reception failure called adjacent interference that causes interference. May occur. Also, in FM broadcasting, the number of broadcasting stations including FM multiplex broadcasting has increased, and the frequency interval with other broadcasting stations has become close, thereby adjacent to the tuning frequency signal of the desired broadcasting station received by the broadcast receiver. The frequency signals of other broadcasting stations are close to each other, causing interference and interference with the frequency signals of other broadcasting stations adjacent to the desired broadcasting station, resulting in an increase in adjacent interference that prevents good reception. ing.
[0003]
The adjacent interfering signal that interferes at this time is not necessarily the station assigned adjacent to the station you want to receive, but you may want to receive it depending on the circumstances of each region, even if the frequency is slightly different from the frequency of the station you want to receive. Interference often occurs due to relatively close proximity to the station and when the radio waves of other nearby stations are relatively strong. A generic term that interferes with appropriate reception by being relatively close to the frequency of the desired reception station and interfering with the received radio wave of the desired reception station is generally called adjacent interference.
[0004]
In order to prevent such interference due to adjacent interference, in a conventional broadcast receiver, for example, adjacent interference is detected by a signal from an electric field strength level detector using an S-meter (Signal Strength Meter) indicating the strength of the received radio wave. This is dealt with by detecting the signal level and selecting a filter with a different frequency band.
[0005]
That is, for example, as in the FM broadcast receiver shown in FIG. 8, the high frequency component of the radio wave received by the antenna 40 is amplified by the high frequency amplifier 41 and input to the mixer 42. On the other hand, a system control unit 44 inputs a seek up / seek down signal in the channel selection unit 43 operated by the user, and a frequency synthesizer type local transmitter 46 is operated in a PLL (Phase Locked Loop) circuit 45 correspondingly. Then, a change in the reception frequency for each fixed frequency step is performed in a direction corresponding to the instruction input signal by digital control, and the frequency signal is input to the mixer 42. In the mixer 42, the received radio wave amplified by the high frequency and the frequency signal are mixed and converted to an intermediate frequency signal of 10.7 MHz.
[0006]
This signal is amplified and detected by the intermediate frequency amplification / detection circuit 47 and output to the filter selection unit 48 for each bandwidth. The band-specific filter selection unit 48 includes, for example, two types of band filters, a wide band filter 50 having a bandwidth of 5 kHz and a narrow band filter 51 having a band width of 2.0 Khz to 2.5 kHz. Select a filter for either band. It should be noted that this band-by-band filter may be provided with more types as necessary, and may be appropriately selected and used.
[0007]
The electric field strength level detector 53 detects a noise component of 100 k beats included in the S-meter signal obtained by rectifying the signal from the intermediate frequency amplification / detection circuit 47, and an adjacent interference level detector 54. Then, the extent to which the radio wave received by this signal is subject to adjacent interference is detected. The electric field strength level detector 53 determines that the reception state is bad when the electric field strength is 2 μV or less, for example, and outputs a band filter selection instruction signal to the bandwidth switching control circuit 55 described later.
[0008]
In the bandwidth switching control circuit 55, when it is determined from the signal in the adjacent interference level detector 54 that the received radio wave has received adjacent interference of a predetermined value or more as described above, the filter selector 52 in the filter selection unit 48 for each band. Is instructed to select the narrow band filter 51 having a narrow pass band. When it is determined that the adjacent interference received by the received radio wave is equal to or less than a predetermined value, the filter selector 52 instructs the wideband filter 50 to be selected.
[0009]
As described above, the narrowband filter 51 is selected by the band-by-band filter selection unit 48 when good reception cannot be performed because the received radio wave of the station desired to receive has received adjacent interference. In this way, adjacent interference components are prevented from passing through as much as possible.
[0010]
[Problems to be solved by the invention]
In the conventional broadcast receiver as described above, when it is determined that good reception cannot be performed due to adjacent interference with the received reception desired radio wave, bands with different passband widths prepared in advance When a filter is selected and a filter with a narrow bandwidth is selected when receiving adjacent interference, if a filter with such a narrow bandwidth is selected, the influence of noise due to adjacent interference may be reduced. Although it was possible, the bandwidth of the desired reception station was narrowed, and there was a problem that the sound became muddy and unclear.
[0011]
Accordingly, the present invention provides a broadcast receiving method and a broadcast receiver that can clearly receive a broadcast signal of a reception-desired station that has received adjacent interference while eliminating adjacent interference and without changing the audio characteristics. The main purpose is to do.
[0012]
[Means for Solving the Problems]
In order to solve the above-described problem, the broadcast receiving method according to the present invention includes a main receiver and a sub-receiver, detects a change in the received electric field strength of the main receiver, and at least changes in the received electric field strength of the main receiver. When it is detected that it is greater than or equal to the predetermined value, it is determined that the adjacent interference removal processing is performed. When the adjacent interference removal processing is performed, the receiving station of the sub-receiver is changed in order from the station closest to the station receiving the main receiver. Detecting fluctuations in the received signal strength of the sub-receiver and locking the sub-receiver's receiving station when the fluctuation is detected to be greater than or equal to the specified value, the adjacent interference included in the radio wave received by the main receiver at this time Obtain the radio wave interference rate, and use the same value as this MPX signal including audio signal Attenuate the main receiver MPX signal including audio signal From the sub receiver MPX signal including audio signal Is output by subtracting.
[0013]
The broadcast receiver according to the present invention includes a main receiver that receives radio waves of a station specified by a user, a main receiver electric field strength fluctuation detection unit that detects fluctuations in the received electric field strength of the main receiver, and at least When the main receiver electric field strength fluctuation detecting unit detects a fluctuation of a predetermined value or more, an adjacent disturbance removing process determining unit for determining that an adjacent disturbance removing process is to be performed, and an adjacent disturbance removing process in the adjacent disturbance removing process determining unit. At the time of output to be performed, the sub-receiver receiving station change specifying unit for instructing the change of the receiving station in order from the side closer to the frequency of the station being received by the main receiver, and the station specified by the sub-receiver receiving station change specifying unit A sub-receiver that receives the radio wave, a sub-receiver electric field strength fluctuation detecting unit that detects fluctuations in the received electric field strength of the sub-receiver, and a sub-receiver electric field strength fluctuation detecting unit that detects a predetermined fluctuation or more. The secondary receiver Receiving station lock designating unit that stops changing the receiving station at the receiving station changing and determining unit, and a cross ratio calculation for obtaining the interference rate of adjacent interfering radio waves included in the received radio wave of the main receiver when the changing of the receiving station is stopped And the interference rate obtained by the interference rate calculation unit to the sub receiver MPX signal including audio signal Of the attenuator that attenuates the main receiver when the change of the receiving station is stopped MPX signal including audio signal Of the secondary receiver from the attenuated MPX signal including audio signal From the main receiver MPX signal including audio signal And the received signal is subtracted by the subtraction processing unit. MPX signal including audio signal And an output reception signal switching unit for switching and outputting.
[0014]
In addition, another broadcast receiver according to the present invention includes a pilot signal fluctuation detection unit that detects a fluctuation of a pilot signal of a received signal at a main receiver, and the adjacent interference removal processing determination unit further includes the pilot signal fluctuation. In the detection unit, it is determined that the adjacent interference removal process is performed when both conditions when a predetermined fluctuation or more is not detected are satisfied.
[0015]
Further, in the other broadcast receiver according to the present invention, in the sub-receiver receiving station change designating unit, the receiving station is changed in order at a frequency interval assigned to the broadcasting station from the side closer to the frequency of the station received by the main receiver. Is specified.
[0016]
Further, another broadcast receiver according to the present invention includes a memory that records a station that can be received in each region and a transmission radio frequency of each station, and the sub-receiver receiving station change designation unit is based on the data in the memory. The change of the receiving station is designated to the receivable stations in order from the side closer to the frequency of the station receiving by the main receiver.
[0017]
Further, in the other broadcast receiver according to the present invention, the sub-receiver receives the same station as the main receiver when it is determined that the adjacent disturbance removal determination unit does not perform the adjacent disturbance removal processing. is there.
[0018]
In another broadcast receiver according to the present invention, the interference rate calculation unit estimates the interference rate of adjacent interfering radio waves from the reception field strength of the main receiver and the reception field strength of the sub-receiver. It is.
[0019]
In addition, another broadcast receiver according to the present invention includes a pilot signal fluctuation detection unit that detects a fluctuation of a pilot signal included in the signal from the subtraction processing unit, and the fluctuation of the pilot signal in the pilot signal fluctuation detection unit is detected. When it is within the predetermined range, it is determined that the sub-receiver is receiving the adjacent interfering station of the main receiver.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an FM broadcast receiver as an example of a broadcast receiver according to the present invention, and is a functional block diagram mainly showing a configuration for performing a function for removing adjacent interference in the present invention. In this figure, this broadcast receiver is provided with a main receiver 2 and a sub-receiver 3, and usually a selection signal from a user input from the operation unit 4 to the system controller 5 by a specific preset key, Alternatively, the receiving station designation unit 6 changes the receiving station in the direction of increasing or decreasing the receiving instruction frequency at a predetermined frequency interval from the initial frequency or from the initial frequency based on the seek up and seek down operation signals. . The signal from the receiving station designating unit 6 is a direct instruction signal for the main receiver 2, and the receiving station for the sub receiver 3 is changed based on a separate receiving station designating signal as described later. It is set as an instruction signal of the receiving station for the sub receiver 3 via the changing unit 7.
[0021]
The main receiver 2 outputs an MPX signal including an audio signal and an electric field strength signal indicating the strength of the radio wave of the desired station received from the antenna 1 by the main receiver 2. Among them, the MPX signal enters the audio DSP processing unit 30 via an MPX signal switching unit 28 (to be described later) in the DSP 10, performs various signal processing for audio output that has been conventionally performed, and outputs the audio output to an amplifier or the like. . The pilot signal fluctuation detection unit 13 detects and inputs a pilot signal in the MPX signal, and the level fluctuation detection unit 11 detects the level fluctuation.
[0022]
In general, when FM radio waves are received with multiple reflections, the FM stereo broadcast signal causes multipath distortion, and the composite stereo signal obtained from the FM demodulator undergoes phase fluctuations under the influence of multipath interference. The degree of this phase fluctuation depends on the degree of multipath interference. Therefore, the degree of phase fluctuation of the pilot signal included in the MPX stereo signal is detected, so that the received radio wave is subjected to multipath noise. Can know.
[0023]
The level fluctuation detection unit 11 in the pilot signal fluctuation detection unit 13 receives a multipath and detects a state in which the pilot signal is fluctuating, and the setting value comparison unit 12 detects that the fluctuation state is within a preset value range. It is compared whether or not there is, and the signal is output to the adjacent disturbance removal processing determination unit 20 for determining whether or not to perform the adjacent disturbance removal processing in the present invention. When the pilot signal fluctuation detector 13 determines that the fluctuation of the pilot signal is larger than the set value, the state of the currently received radio wave is greatly influenced by multipath noise in addition to the influence of adjacent noise described later. Therefore, it is assumed that the adjacent disturbance removal processing determination unit 20 uses basic data for determining that it is not appropriate to perform the adjacent disturbance processing according to the present invention.
[0024]
The electric field strength signal is input to the main receiver electric field strength variation detector 16 in the DSP 10, and the level variation detector 14 detects the level variation of the input signal in the same manner as the pilot signal variation detector 13. It should be noted that various means can be adopted to detect the level fluctuation of the electric field strength signal. For example, the amplitude of the electric field strength signal is always detected, and the frequency of the amplitude greatly changing within a predetermined time and the level of the amplitude. It is also possible to obtain a variation value based on the difference and obtain data based on that value. When the fluctuation of the electric field strength is large, it can be estimated that the radio wave of the currently desired receiving station is subjected to adjacent interference, so this signal obtained by the set value comparison unit 15 is removed from the adjacent interference. The data is input to the process determination unit 20 and is used as basic data for this determination.
[0025]
On the other hand, the sub-receiver 3 receives the same station as that of the main receiver 2 during normal operation, and this electric field strength signal is used to detect fluctuations in the electric field strength of the main receiver 2. A sub-receiver electric field strength fluctuation detecting unit 19 having the same configuration as that of the unit 16 is provided, and the operations of the level fluctuation detecting unit 17 and the set value comparing unit 18 are the same as described above. A signal indicating the degree of fluctuation of the electric field strength of the sub-receiver 3 obtained by the set value comparison unit 18 is also input to the adjacent disturbance removal processing determination unit 20 in the same manner as described above and used as basic data for determination.
[0026]
The MPX signal that is an audio signal from the sub-receiver 3 is different from the MPX signal that is output from the main receiver 2 and then becomes an audio output signal. As will be described later, a subtraction process is performed on the MPX signal of the main receiver. Used as a signal to do. The MPX signal from the sub-receiver 3 is attenuated by the attenuator 23 based on the signal from the interference rate calculation unit 9 that calculates the interference rate based on the electric field strength data of the main receiver and the sub-receiver. Attenuation processing is performed with the amount of attonate set by, and output to the MPX signal subtraction processing unit 26 via the delay unit 25.
[0027]
In the MPX signal subtraction processing unit 26, the MPX signal of the main receiver 2 is also input while being synchronized via the delay unit 24, and this is synchronized with this from the MPX signal of the main receiver as will be described later. Then, the MPX signal attenuated by a predetermined attenuation amount is subtracted by the signal of the system controller 5, and this is used as one selection output signal in the MPX signal switch 28. The MPX signal subtraction processing unit 26 is operated by an output signal indicating that a condition as will be described later is satisfied in the adjacent disturbance removal processing determination unit 20, and at the same time, the adjacent disturbance removal processing determination unit 20 operates the output signal switching unit 27. At this time, the subtracted signal is output to the audio DSP processing unit 30 and output to the outside as an audio signal.
[0028]
The MPX signal subtracted by the MPX signal subtraction processing unit 26 is input to the pilot signal fluctuation detection unit 32, detects the fluctuation level of the pilot signal included in the MPX signal after the subtraction process, and determines to the adjacent disturbance removal process determination 20. Input and used as basic data for discrimination. When the fluctuation of the pilot signal included in the MPX signal after the subtraction process is smaller than a predetermined value, it can be determined that the receiving station of the sub receiver 3 is an interfering station.
[0029]
The adjacent interference removal processing determination unit 20 outputs a signal to the sub-receiver receiving station change designating unit 21 under a predetermined condition to be described later, and the sub-receiver receiving station change designating unit 21 every time this signal is input. The data of the broadcast station frequency list memory 29 that stores the broadcast stations that can be received in each region in advance and the frequencies of the broadcast stations in the order of frequency are read out in the order as described later, or the data are read in the order of predetermined separation frequencies. The data is output to the receiving station changing unit 7 and the receiving station of the sub receiver 3 is changed. When the sub-receiver electric field strength fluctuation detecting unit 19 determines that the electric field strength level fluctuation is equal to or greater than the set value, the receiving station lock designating unit 31 stops the change designation in the sub-receiver receiving station change designating unit 21. Lock the receiving station.
[0030]
In the broadcast receiver configured as described above, its operation can be performed, for example, according to the operation flow shown in FIG. The operation flow will be described below together with the block diagram of FIG. 1 and the drawings showing various operations of FIGS.
[0031]
In the process during the broadcast reception of the broadcast receiver, the electric field strength of the main receiver is first detected (step S1), and then the level fluctuation of the electric field strength is detected based on the electric field strength signal (step S2). Further, it is determined whether or not the level fluctuation of the electric field intensity is a set value or more (step S3). These processes are performed in the main receiver electric field strength fluctuation detector 16 in FIG. 1 as described above.
[0032]
When it is determined that the variation in the electric field intensity is not equal to or greater than the set value, the process proceeds to step S18, and the received MPX of the main receiver that is currently received is output as it is without being subjected to adjacent noise processing. In this case, it is natural that multipath noise removal processing or the like can be separately performed as necessary.
[0033]
On the other hand, in the determination of whether or not the fluctuation of the electric field intensity is greater than or equal to a set value, if it is determined that there is a fluctuation greater than or equal to the set value, the pilot signal of the main receiver is detected as the first processing (step Next, a change in the pilot signal is detected (step S5), and it is further determined whether or not the fluctuation is within a set range (step S6). These processes are performed in the pilot signal fluctuation detector 13 in FIG.
[0034]
As a result of this determination, when it is determined that the fluctuation of the pilot signal of the main receiver is greater than or equal to the set value, the radio wave received by the main receiver is greatly affected by the radio waves reflected on the mountains, buildings, etc. Since the radio wave is causing multipath noise, it is considered that the adjacent interference removal process by the subtraction process as described later according to the present invention is difficult, and the process returns to step S1 again, and the above process is performed until at least the multipath noise is stabilized. repeat. As a result of the determination, when it is determined that the fluctuation of the pilot signal is within the set range, the process proceeds to the next step 11 together with a signal to be described later.
[0035]
In step S3, as a second process when it is determined that the level fluctuation of the electric field strength of the main receiver is greater than or equal to the set value, the electric field strength of the sub receiver is detected (step S7). Next, the level fluctuation of the electric field strength is detected (step S8), and it is further determined whether or not the fluctuation is equal to or greater than a set value (step S9). These processes are performed in the sub-receiver electric field strength fluctuation detector 19 in FIG.
[0036]
As a result of this determination, when it is determined that the level variation of the electric field strength of the sub-receiver is not equal to or greater than the set value, it is then determined whether or not this determination is the first determination process (step S10). That is, since the main receiver and the sub-receiver are receiving the same station at the beginning, when it is determined in step 3 that the level fluctuation of the electric field strength of the main receiver is equal to or higher than the set value, naturally this time. Since the fluctuation in the level of the electric field strength of the sub-receiver is equal to or greater than the set value, the process proceeds to step S19 only for the first determination, and processing for changing the reception frequency of the sub-receiver in a predetermined order is performed. Further, when it is determined in step S9 that the level fluctuation of the electric field strength of the sub-receiver is not equal to or greater than the set value, the process proceeds to step S19, and the reception frequency of the sub-receiver is changed in a predetermined order as described above. At this time, the processing is after the determination that the determination processing is not the first time in step S10.
[0037]
The process of changing the reception frequency of the sub-receiver in the predetermined order in step S19 is performed in the sub-receiver receiving station change designating unit 21. At this time, the area-specific receivable broadcasting station frequency list prepared in advance as described above. This is performed using the data in the memory 29. However, the reception frequency can be changed in order at predetermined frequency intervals without using such data. FIG. 4 shows an example of operation when it is assumed that there is a broadcasting station capable of receiving in this region at a frequency portion separated by 100 kHz from the desired reception station in order to explain this operation in an easy-to-understand manner. When it is determined that the determination process is the first (n = 1), the reception frequency of the sub-receiver is changed to a frequency 100 kHz higher than the desired reception station.
[0038]
Such a change is made in the receiving station changing unit 7 in FIG. 1. In this example, the same station as the main receiver 2 was first specified in the receiving station specifying unit 6, but the sub receiver receiving station change The receiving station is changed according to the instruction from the designating unit 21. As a result of this change processing, the sub-receiver receives a station whose frequency is 100 kHz higher than the desired receiving station, and returns to step S7 again to set the variation in the field strength of the sub-receiver in the same manner as described above. It is determined whether or not it is greater than or equal to the value. As a result, when it does not exceed the set value yet, that is, when it is determined that the radio wave of the station that is adjacent to the radio wave of the desired reception station that the main receiver is receiving has not been received, the secondary reception is performed again. A process of changing the reception frequency of the machine in a predetermined order is performed.
[0039]
In the above example, as shown in FIG. 4A, since the receivable frequencies are arranged at intervals of 100 kHz, the frequency that is 100% lower than the frequency of the desired reception station that is likely to cause the next adjacent interference. Of the other station. If it is still determined that the station that has caused the adjacent interference to the reception desired station of the main receiver has not been received yet, a station having a frequency higher by 200 kHz than the next desired reception desired station is received. Such a process of changing the reception frequency is repeated, and in the illustrated embodiment, a station having a frequency higher by 300 kHz than the frequency of the desired reception station, which is a station giving adjacent interference by the frequency change process five times (n = 5). Will be received. As a result, in step S9, it is determined that the level variation of the electric field strength of the sub-receiver is equal to or greater than the set value, and in step S10, it is determined that it is not the first determination process, so the process proceeds to step S11. In the operation of seeking the reception frequency in the sub-receiver, for example, as shown in FIG. 4B, based on the data in the regional receivable broadcast station frequency list memory 29 in FIG. , R station, then S station in order, and finally find the adjacent interfering station that is 300 kHz away from the desired receiving station.
[0040]
As described above, in step S6, it is determined that the fluctuation of the pilot signal of the main receiver is within the range of the set value, and in step S9, it is determined that the level fluctuation of the electric field strength of the sub-receiver is greater than or equal to the set value. If the determination in step S9 is not the first determination process, it is determined in step S11 whether or not both signals are input simultaneously, that is, whether or not both conditions are satisfied simultaneously. When one of them is not satisfied, that is, when only one of them is inputted, the subsequent subtraction processing is not performed, the operation is repeated by returning to step S1, and the next processing is not performed until the above condition is satisfied.
[0041]
In the step S19, when the process of changing the reception frequency of the sub-receiver is performed in a predetermined order, in the embodiment shown in FIG. 2, the process returns to step S7 and the level variation of the electric field strength of the sub-receiver exceeds the set value. In the example shown in FIG. 1, the process returns to step S1, for example, whether or not the fluctuation in the level of the electric field strength of the main receiver is greater than or equal to the set value, and whether the previous adjacent interference state has changed. After confirming the above, it may be detected whether or not the electric field strength level is equal to or higher than a set value in a new station received by the sub-receiver.
[0042]
When it is determined in step S11 that the above condition is satisfied, it is determined in the sub-receiver that the fluctuation in the level of the electric field strength of the specific station searched in the order closer to the reception desired station of the main receiver is greater than or equal to the set value. As a result, it is possible to identify a station that may be causing adjacent interference to the main receiver, so that the reception frequency of the sub receiver is locked to that station. That is, the reception frequency of the sub receiver is locked to a frequency that may cause adjacent interference to the main receiver (step S12).
[0043]
Next, receive the reception desired station while receiving the adjacent disturbance and the field intensity data of the sub-receiver in the state where reception is locked to the station that may have caused adjacent interference to the main receiver as described above. Based on the field strength data of the main receiver, the rate at which the main receiver is receiving adjacent interference is calculated, and this is set as the attenuation amount for the MPX signal currently received by the sub-receiver (step S13). The attenuation amount setting is performed in the attenuation amount setting unit 22 in FIG. 1. At the time of setting, the electric field strength data of the main receiver 2 and the electric field strength of the sub-receiver 3 input to the interference rate calculation unit 9 are set. Calculate the attenuation amount and set the attenuation amount.
[0044]
Thereafter, the MPX signal of the sub receiver that has been attenuated is subtracted from the MPX signal of the main receiver (step S14), thereby removing adjacent interference from the MPX signal of the main receiver that is receiving adjacent interference. The principle is shown in FIG. 3, in which the MPX signal of the main receiver is shown as fm in the figure. This signal is obtained by adding the MPX signal fa of the station desired to receive and the MPX signal fb ′ as adjacent interference (fm = fa + fb ′).
[0045]
Also, the MPX signal of the sub-receiver receiving the station that is causing adjacent interference to the main receiver is indicated by fs in the figure, and this signal is MPX that has received the radio wave of the station that is causing adjacent interference. The signal fb is added to the MPX signal fa ′ as the adjacent interference by the desired receiving station received by the main receiver by giving adjacent interference to each other (fs = fa ′ + fb).
[0046]
At this time, the adjacent interference between the main receiver and the sub-receiver is similar to each other. When the degree of this interference is J, fb ′ is represented by (J × fb), and similarly, fa ′ is ( J × fa). In the figure, fm and fs are shown to have the same size for the sake of simplifying the subsequent calculation. However, when the MPX sizes of the main receiver and the sub-receiver are different, the same level can be obtained by using amplification means. It can be.
[0047]
Attenuation set to substantially the same value as the degree of interference J calculated from the electric field strength signals of the main receiver and the sub-receiver as described above with respect to the MPX signal fs of the sub-receiver expressed as described above. Attenuate by the amount K. As a result, as shown in FIG. 3, the attenuated MPX signal of the sub-receiver is expressed by K × fs, and when the component of the signal is viewed, fa ′ is fa ″ (fa ″ = fa ″ = K × fa ′), and fb is fb ″ (fb ″ = K × fb) due to K-times attenuation. Here, when K≈J is set, particularly fb ″ is substantially the same as fb ′ of MPX which gives adjacent interference to the main receiver.
[0048]
Therefore, when the MPX signal attenuated by the sub-receiver is subtracted from the fm of the MPX signal received by the main receiver to obtain a signal of fm−K × fs, the main disturbance from which the adjacent interference is removed in FIG. As shown as the MPX signal of the receiver, the adjacent disturbance fb ′ is removed from the MPX signal fm of the main receiver. At this time, the MPX signal of the desired reception station received by the main receiver is also a signal reduced by fa ″, but the influence on the MPX signal is less than that when passing through a conventional narrow band filter, and at least adjacent to the MPX signal. The effect of removing interference is much greater.
[0049]
FIGS. 5 to 7 schematically show the actual reception radio wave signal for the effect of removing such adjacent interference. That is, in FIG. 5, the waveform of the desired reception station received by the main receiver is indicated by fa as the waveform of the first frequency. Further, the original waveform transmitted from the station mixed in the main receiver and causing adjacent interference is indicated by fb as the second frequency waveform.
[0050]
When these waves are adjacent to each other, assuming that the degree of interference is J as described above, adjacent interference is performed in the form of J × fa and J × fb waveforms each having a reduced amplitude. As shown in FIG. 6A, the signal of the main receiver receiving the adjacent interference in this way is a composite wave of the first frequency and the second frequency that is adjacent to the first frequency. Similarly, the signal of the sub-receiver receiving the station that is causing adjacent interference to the main receiver becomes adjacent noise with respect to the second frequency as shown in FIG. The synthesized wave of the first frequency. These synthesized waves are indicated by bold lines in each figure.
[0051]
Among these, when K-times attenuation is performed on the synthesized wave shown in FIG. 6B as described above, the synthesized wave in FIG. 6B shown in FIG. As shown in FIG. 7 (b), the amplitude decreases. This wave is subtracted from the synthesized wave shown in FIG. 6A as a wave for subtraction correction. As a result, as indicated by the thick line in FIG. 7 (c), the adjacent signal is removed from the combined wave in FIG. 6 (a) that has been subjected to adjacent interference, and is substantially the same as the original signal wave shown as fa in FIG. It can be seen that a signal wave can be obtained.
[0052]
The MPX signal subjected to the subtraction process in step S14 operates according to the basic principle of the present invention as described above, and the adjacent noise is removed in principle as a result of being processed as represented by the simulated waveform. However, in this embodiment, the variation of the pilot signal included in the subtraction processing waveform is detected, and it is determined whether or not the variation of the pilot signal of the MPX signal after the subtraction processing is equal to or less than a predetermined value (step S15). The pilot signal fluctuation is detected by the pilot signal fluctuation detecting unit 32 in the subtraction processing waveform in FIG. When the fluctuation of the pilot signal is equal to or less than the predetermined value, the adjacent interference removal processing determination unit 20 determines that the station being received by the sub-receiver 3 is an interference station, and proceeds to step S16. If the pilot fluctuation of the MPX signal after the subtraction process exceeds a predetermined value, the process returns to step S7, the receiving station of the sub receiver is changed, and the same process as described above is continued.
[0053]
In step S16, audio output is performed using the subtracted MPX signal, and it is further determined whether or not there is an instruction to end reception by turning off the power of the receiver (step S19). Returning to step S1, the process is repeated from the detection of the electric field strength of the main receiver. When there is an instruction to end reception, this flow is ended (step S20).
[0054]
In the above embodiment, the example in which the present invention is applied to the FM broadcast receiver has been shown, but the present invention can be similarly applied to the AM broadcast receiver. At that time, the pilot signal fluctuation or the like is not used. Moreover, if it is a broadcast receiver which can be provided with the main function part of this invention, it can apply similarly to other various broadcast receivers.
[0055]
【The invention's effect】
The broadcast receiving method and the broadcast receiver according to the present invention can reliably remove the signal component of the adjacent interference from the reception signal of the reception desired station that is receiving the adjacent interference, and the audio characteristics of the reception signal of the reception desired station. There is no change.
[0056]
A pilot signal fluctuation detection unit that detects a fluctuation of a pilot signal of the received signal at the main receiver, and the adjacent interference removal processing determination unit further detects no fluctuations greater than a predetermined value in the pilot signal fluctuation detection unit In a broadcast receiver that determines that adjacent interference removal processing is performed when both of the above conditions are satisfied, the above processing according to the present invention is not performed when multipath noise is present in the received radio wave of the main receiver, and the optimal condition is Only the adjacent interference removal process can be performed.
[0057]
Further, in the broadcast receiver that specifies the change of the receiving station in order from the side closer to the frequency of the station that is being received by the main receiver in the sub-receiver receiving station change designating unit, the main reception Stations that are causing adjacent disturbance to the aircraft can be reliably detected.
[0058]
In addition, it has a memory that records the stations that can be received in each region and the transmission radio frequency of each station,
Broadcast receiver that designates the change of the receiving station to the receivable stations in order from the side closer to the frequency of the station that is received by the main receiver based on the data in the memory in the sub receiver receiving station change designation unit In, the station that is causing adjacent interference to the main receiver can be detected reliably and quickly, and adjacent interference removal processing can be performed quickly.
[0059]
In addition, when the adjacent interference removal determining unit determines that the adjacent interference removal processing is not performed, in the broadcast receiver in which the sub-receiver receives the same station as the main receiver, the sub-receiver performs the adjacent interference removal processing in advance. Therefore, when it is necessary, the process can be started immediately. Also, when searching for a station that is causing adjacent interference to the main receiver, the sub receiver It is possible to perform processing to find from nearby, and it is possible to quickly detect a station that is causing adjacent interference.
[0060]
Further, in the broadcast receiver that obtains the interference rate of adjacent interfering radio waves from the reception electric field strength of the main receiver and the reception electric field strength of the sub-receiver in the interference rate estimation unit, the interference rate can be obtained reliably. Since the amount of attenuation with respect to the received signal of the sub-receiver based on this value can be obtained accurately, the adjacent interference elimination processing can be performed reliably.
[0061]
A pilot signal fluctuation detecting unit that detects a fluctuation of a pilot signal included in the signal from the subtraction processing unit, and when the fluctuation of the pilot signal in the pilot signal fluctuation detecting unit is within a predetermined range, In the broadcast receiver that determines that the receiver receives the adjacent jamming station of the main receiver, the sub-receiver has received the jamming station by detecting the fluctuation of the pilot signal included in the signal of the subtraction processing unit. Can be reliably determined, and adjacent interference can be reliably removed.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of an embodiment of a broadcast receiver according to the present invention.
FIG. 2 is an operation flowchart of the embodiment of the present invention.
FIG. 3 is a diagram illustrating a basic principle of adjacent interference removal according to the present invention.
FIGS. 4A and 4B are diagrams illustrating a method for searching for a station that is causing adjacent interference according to the present invention, in which FIG. 4A is a diagram illustrating a mode of sequentially searching for reception frequencies of a sub-receiver at a predetermined separation frequency; It is a figure of the aspect which searches a receivable station in order.
FIG. 5 is a diagram illustrating a signal waveform of a frequency desired for reception and a frequency giving adjacent interference in an example in which adjacent interference is removed by the present invention.
FIG. 6 shows an example of a received signal from which adjacent interference is removed according to the present invention; a signal waveform when receiving a reception desired station mixed with adjacent noise and a station receiving adjacent interference; It is a figure which shows a signal waveform.
FIG. 7 shows an example of a received signal from which adjacent interference is removed according to the present invention, a signal waveform obtained by attenuating a signal received by a station that gives adjacent interference, and a reception request in which adjacent noise is mixed with this signal waveform. It is a figure which shows that the adjacent disturbance is removed by subtracting from the signal waveform of a station.
FIG. 8 is a functional block diagram showing an example of adjacent interference processing in a conventional broadcast receiver.
[Explanation of symbols]
2 Main receiver
3 Sub receiver
5 System controller
6 Receiving station designation part
7 Receiving station change part
9 Interference rate calculator
10 DSP
11 Level fluctuation detector
12 Set value comparison unit
13 Pilot signal fluctuation detector
16 Main receiver electric field strength fluctuation detector
19 Sub-receiver electric field strength fluctuation detector
20 Adjacent disturbance removal processing discriminator
21 Sub receiver receiving station change designation section
22 Attenuation amount setting section
23 Attenuator
24 delay unit
25 Delay device
26 MPX signal subtraction processing unit
27 Output signal switching part
28 MPX signal switching section
30 Audio DSP processor
31 Receiving station lock designation part

Claims (8)

It has a main receiver and a sub receiver
Detects fluctuations in the received field strength of the main receiver,
It is determined that the adjacent interference elimination processing is performed at least when it is detected that the fluctuation of the reception field strength of the main receiver is equal to or greater than a predetermined value
When performing adjacent interference elimination processing, change the receiving station of the secondary receiver in order from the station closest to the station receiving by the main receiver,
Detects fluctuations in the received signal strength of the sub receiver, and locks the receiving station of the sub receiver when it detects that the fluctuation is greater than or equal to a predetermined value.
At this time, obtain the interference rate of the adjacent jamming radio wave included in the radio wave received by the main receiver,
Attenuate the MPX signal including the audio signal of the sub receiver with the same value as this interference rate,
A broadcast receiving method comprising: subtracting an MPX signal including an audio signal of the sub receiver from an MPX signal including an audio signal of a main receiver, and outputting the subtracted MPX signal . A main receiver that receives the radio waves of the station specified by the user;
A main receiver electric field strength fluctuation detector for detecting fluctuations in the received electric field strength of the main receiver;
An adjacent disturbance removal processing determination unit for determining that adjacent disturbance removal processing is performed when at least a predetermined variation is detected in the main receiver electric field strength variation detection unit;
Sub-receiver receiving station change designating unit for instructing the change of the receiving station in order from the side closer to the frequency of the station received by the main receiver at the time of output for performing the adjacent interference removing process in the adjacent interference removing process determining unit,
A sub-receiver that receives the radio waves of the station designated by the sub-receiver receiving station change designation unit;
A sub-receiver electric field strength fluctuation detector for detecting fluctuations in the received electric field strength of the sub-receiver;
A receiving station lock designating unit for stopping the change of the receiving station in the sub-receiver receiving station change determining unit when detecting a variation of a predetermined value or more in the sub-receiver electric field strength variation detecting unit;
A cross rate calculation unit for obtaining a crosstalk rate of adjacent interfering radio waves included in the received radio wave of the main receiver when the change of the receiving station is stopped;
An attenuator for attenuating the MPX signal including the audio signal of the sub-receiver in the interference rate obtained by the interference rate calculation unit;
A subtraction processing unit for subtracting the MPX signal including the attenuated audio signal of the sub receiver from the MPX signal including the audio signal of the main receiver when the change of the receiving station is stopped;
An output reception signal switching unit that switches between an MPX signal including an audio signal from a main receiver and an MPX signal including an audio signal obtained by subtracting the reception signal by the subtraction processing unit. Broadcast receiver.   A pilot signal fluctuation detecting unit for detecting fluctuations in the pilot signal of the received signal at the main receiver, and the adjacent interference removal processing determining unit further includes both when the pilot signal fluctuation detecting unit does not detect fluctuations greater than a predetermined value. 3. The broadcast receiver according to claim 2, wherein it is determined that the adjacent interference removal processing is performed when the condition is satisfied.   3. The sub-receiver receiving station change designating unit designates changing of receiving stations in order at a broadcasting station assigned frequency interval from the side closer to the frequency of the station receiving by the main receiver. Broadcast receiver.   It has a memory that records the stations that can be received in each area and the transmission radio frequency of each station, and the sub-receiver receiving station change designation unit sets the frequency of the station that is received by the main receiver based on the data in the memory. 3. The broadcast receiver according to claim 2, wherein a change of a receiving station is designated to the receivable stations in order from the closest side.   3. The broadcast receiver according to claim 2, wherein the sub-receiver receives the same station as the main receiver when it is determined by the adjacent interference cancellation determination unit that the adjacent interference cancellation processing is not performed.   The broadcast receiver according to claim 2, wherein the interference rate calculation unit obtains an interference rate of adjacent interfering radio waves based on a reception electric field strength of a main receiver and a reception electric field strength of a sub receiver.   A pilot signal fluctuation detection unit that detects a fluctuation of a pilot signal included in the signal from the subtraction processing unit, and when the fluctuation of the pilot signal in the pilot signal fluctuation detection unit is within a predetermined range, the sub receiver 3. The broadcast receiver according to claim 2, wherein it is determined that an adjacent jamming station of the receiver is being received.

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