JP2003174373A - Equipment for detecting interference of signals in adjacent channels and method, and broadcast receiving equipment capable of using the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable accurate detection of generation of a interferent station in a wide range of DU ratio under the condition that intermodulation is generated. <P>SOLUTION: An adjacent interference detector 200 is equipped with a first system adjacent interference detector 202 for obtaining difference between a signal which has passed a broad-band filter whose center frequency is a desired wave and a signal which has passed a narrow-band filter whose center frequency is the desired wave, a second system adjacent interference detector 204 for obtaining the sum of an output of a filter which passes disturbing wave components lower than the desired wave and an output of a filter which passes disturbing components higher than the desired wave, and a DU ratio deciding part 210 for detecting disturbing wave on the basis of the output of the first system detector 202 when an intensity ratio of the desired wave to the disturbing wave is at most a prescribed threshold value, and based on the output of the second system detecting part 204 when the intensity ratio exceeds the prescribed threshold value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adjacent interference detecting apparatus and method capable of automatically detecting a state of adjacent interference in a broadcast receiving apparatus such as FM broadcast, and a broadcast receiving apparatus using the same. Regarding configuration.

[0002]

2. Description of the Related Art Generally, in an FM radio receiver or the like, when an interfering signal occurs adjacent to a broadcast signal from a desired broadcasting station, so-called "adjacent interference" causes deterioration of communication quality.

Therefore, when such adjacent interference occurs, it is detected and the receiver side down-converts the received signal, for example, an intermediate frequency signal (IF signal).
Measures are taken such as changing the pass band width of the IF filter that passes the signal. However, in Europe, for example, since channels are adjacent to each other in units of 100 KHz, it is not possible to remove interference signals only by adjusting the pass band of the IF filter.
Adjacent interference countermeasures are one issue in the design of FM receivers and the like.

As a method of detecting the presence or absence of such an interfering signal, for example, Japanese Patent Laid-Open No. 8-97738 first compares the energy contained in a wide band and a narrow band centered on the frequency of the desired wave, and A method of detecting the presence of adjacent interference based on the comparison result is disclosed.

Alternatively, in Japanese Unexamined Patent Publication No. 5-191312, an intermediate frequency filter detects an interfering wave existing in the upper and lower frequency bands of a desired reception signal, differentially amplifies the detection output, A technique is disclosed in which the center frequency of the IF filter for the desired signal is moved to the direction in which the energy of the interfering wave is smaller, according to the differential amplification output.

[0006]

According to the conventional technique described above, it is possible to detect an adjacent interfering wave under a specific condition, but there are the following problems.

First, in the invention disclosed in Japanese Unexamined Patent Publication No. 8-97738, the intensity ratio between the desired wave and the interfering wave (hereinafter referred to as the DU ratio) will be seen when intermodulation described later occurs. However, there is a problem that the range of the DU ratio that can be detected becomes narrow.

On the other hand, the other Japanese Patent Laid-Open No. 5-191312
Even in the method disclosed in the publication, under the condition that the intermodulation interference occurs, the original interference station and the modulation interference generated by such intermodulation appear so as to sandwich the desired station. There was a problem of causing it.

The intermodulation interference will be described in more detail below. FIG. 11 is a conceptual diagram for explaining such intermodulation.

A reception wave is also amplified in a front end portion of an FM receiver or the like which receives a reception signal from an antenna and converts it into an intermediate frequency. However, a signal which has passed through such an amplifier has a so-called intermodulation distortion. Occurs.

As shown in FIG. 11, when two or more signals having different frequencies, for example, signals having frequencies fa and fb, are input to the high frequency amplifier, they are generated due to mutual input signals or non-linearity of the amplifier. Intermodulation with high frequency causes so-called "spurious" at the output of the amplifier. That is, new interfering signals due to intermodulation may occur on both sides of the signal input to the amplifier.

FIG. 12 is a conceptual diagram showing the effect of such intermodulation interference on the presence of an interfering station in the FM receiver or the like as described above.

As shown in FIG. 12, when a disturbing signal from the disturbing station is generated near the frequency F of the desired station on the frequency side deviated by + Δf with respect to the frequency of the desired station, FIG.
Due to the effect of the intermodulation as described in 1, a spurious signal is generated at a position on the opposite side of the signal of the interfering station with respect to the signal of the desired station, which is shifted by -Δf from the frequency of the signal of the desired station.

Therefore, for example, the above-mentioned Japanese Patent Laid-Open No.
In the invention as disclosed in Japanese Patent Laid-Open No. 191312, since the generation of the interfering wave is detected by the differential amplification of the signal levels on both sides of the signal from the desired station, there is a problem that an erroneous determination occurs. is there.

The present invention has been made to solve the above problems, and an object thereof is to accurately detect the occurrence of an interfering station in an FM broadcast receiver or the like over a wide DU ratio range. It is an object of the present invention to provide an adjacent interference detection device capable of doing so and a broadcast receiving device using the same.

[0016]

One aspect of the present invention relates to an adjacent interference detection device. This device includes a first detection unit that outputs a difference value of signal outputs that have passed through two band filters having different pass bands centered on the frequency of the desired wave, and a frequency that is higher or lower than the frequency of the desired wave. A second detection unit that outputs an added value of signal outputs that have passed through two band-pass filters having a center frequency, and the first detection unit according to an output level of an interfering wave generated adjacent to the desired wave.
And an intensity ratio determination unit that determines an output value of any one of the plurality of detection units including the second detection unit and determines the intensity ratio between the desired wave and the interfering wave.

The output level of the interfering wave may be determined by comparing the output value of the first or second detector with a predetermined threshold value. When the output level of the interfering wave is higher than a predetermined threshold value, the intensity ratio determination using the output value of the first detection unit is performed, and when the output level of the interfering wave is lower than the predetermined threshold value, the first 2 The intensity ratio determination may be performed using the output value of the detection unit.

In the first detecting section, a wide band filter having a pass band wide enough to include adjacent interfering waves on both sides with the frequency of the desired wave as the center, and the frequency of the desired wave as the center,
A narrow band filter having a narrow pass band that does not include adjacent interference waves on both sides may be used. In the second detection unit, two bandpass filters each having a relatively narrow passband that does not include a desired wave may be used, where the vicinity of the frequencies of the adjacent interfering waves on both sides is the passband. The two band-pass filters used in the second detector include a band-pass filter whose center frequency is lower than the desired wave and whose upper limit is lower than the center frequency of the desired wave, and whose lower limit is lower than the center frequency of the desired wave. It may be a filter having a band exceeding the center frequency of the desired wave.

It further includes a third detector for outputting the difference value of the signal outputs that have passed through two band-pass filters whose center frequencies are frequencies higher and lower than the frequency of the desired wave, respectively. The intensity ratio may be determined by selecting the output value of any one of the plurality of detection units including the first, second, and third detection units. The output level of the interfering wave is divided into three levels, the intensity ratio is determined using the difference value output by the first detection unit in the high output level range, and the third ratio is determined in the low output level range. The intensity ratio may be determined using the difference value output by the detection unit, and the intensity ratio may be determined using the added value output by the second detection unit in the other intermediate range. By using the difference value by the third detector, the intensity ratio can be accurately determined even when the desired wave has a high degree of modulation.

The passband widths of the two bandpass filters used in the third detector are made larger than the passbandwidths of the two bandpass filters used in the second detector to spread the frequency of the desired wave. The pass band may include a certain amount.

The second detecting section further outputs a difference value of signal outputs that have passed through the two band-pass filters whose center frequencies are frequencies higher and lower than the frequency of the desired wave, respectively, and the strength determining section The intensity ratio may be determined by selecting one of the difference value output by the first detection unit, the addition value output by the second detection unit, and the difference value. The two band-pass filters of the second detection unit can be shared to obtain the addition value and the difference value, and the configuration can be simplified.

Another aspect of the present invention also relates to an adjacent interference detecting device. This device includes a first detection unit that outputs a sum of signal outputs that have passed through two band-pass filters whose center frequencies are frequencies higher and lower than the frequency of the desired wave, and a frequency higher than the frequency of the desired wave. A second detector that outputs a difference value of signal outputs that have passed through two bandpass filters each having a low frequency as a center frequency, and the first detector according to an output level of an interfering wave generated adjacent to the desired wave. And an intensity ratio determination unit that selects one of the output values of the second detection unit and determines the intensity ratio of the desired wave and the interference wave. Set the output level of the interfering wave to 3
Dividing into stages, in the high range and the low range of the output level, based on the difference value by the second detection unit, in the other intermediate range, based on the added value by the first detection unit, The intensity ratio between the desired wave and the interfering wave may be determined.

Another aspect of the present invention relates to a broadcast receiving device. This apparatus includes a front end unit that converts an FM broadcast signal received from a desired station into an intermediate frequency signal, and an adjacent interference detection unit that detects the intensity of an interference wave adjacent to the desired wave based on the intermediate frequency signal. An intermediate frequency filter section for filtering the intermediate frequency signal according to the strength of the interfering wave and outputting the same; an FM detection section for outputting an FM demodulated signal based on the output signal from the intermediate frequency filter section; And a stereo demodulation unit for stereo demodulating the demodulated signal and outputting the demodulated signal. The adjacent interference detection unit, a plurality of detection units for detecting and outputting the output level of the interference wave by filtering the signal of the interference wave in a peripheral frequency region of the frequency of the desired wave by different methods, and the interference wave One of the plurality of detection units according to the output level of
An intensity ratio determination unit that determines one output value and determines the intensity ratio between the desired wave and the interfering wave is included.

The plurality of detectors are higher than the frequency of the desired wave, and a first detector that outputs a difference value of signal outputs passing through two bandpass filters having different pass bands around the frequency of the desired wave. It may include a second detection unit that outputs the added value of the signal outputs that have passed through the two band-pass filters whose center frequencies are the frequency and the low frequency, respectively. The plurality of detection units outputs a difference value of signal outputs that have passed through two band-pass filters whose center frequencies are frequencies higher and lower than the frequency of the desired wave, respectively.
A detection unit may be further included.

The intermediate frequency filter unit may adjust the bandwidth of a bandpass filter that passes the intermediate frequency signal according to the intensity ratio. The stereo demodulation unit may adjust the degree of separation of the left and right channels in the stereo sound according to the intensity ratio. The stereo demodulation unit may change a ratio of removing a high frequency component of the FM demodulated signal according to the intensity ratio.

Another aspect of the present invention relates to a method for detecting adjacent disturbance. This method includes a first detection step of outputting a difference value of signal outputs passing through two band-pass filters having different pass bands centering on a frequency of a desired wave, and centering frequencies higher and lower than the frequency of the desired wave respectively. A second detecting step of outputting an added value of signal outputs that have passed through two band filters having frequencies, and the first and second detecting steps according to an output level of an interfering wave generated adjacent to the desired wave. A determination step of selecting an output value of any one of the steps to determine the intensity ratio of the desired wave and the interfering wave.

The method further includes a third detecting step of outputting a difference value of signal outputs that have passed through two band-pass filters each having a center frequency of a frequency higher than the frequency of the desired wave and a frequency lower than the frequency of the desired wave. The output value of any one of the first, second, and third detection steps may be selected to determine the intensity ratio.

Another aspect of the present invention also relates to a method for detecting adjacent disturbance. This method includes a first detection step of outputting an added value of signal outputs that have passed through two band filters having center frequencies respectively higher and lower than the frequency of the desired wave, and a frequency higher than the frequency of the desired wave. A second detection step of outputting a difference value of signal outputs that have passed through two band-pass filters each having a low frequency as a center frequency, and an output level of an interfering wave generated adjacent to the desired wave are divided into three stages, In the range where the output level is high and in the range where the output level is low, the desired wave and the interfering wave are generated based on the difference value in the second detection step, and in the other intermediate ranges based on the added value in the first detection step. Determination step of determining the intensity ratio of.

Another aspect of the present invention relates to an adjacent interference detecting device for detecting an adjacent interference wave in a peripheral frequency region of a desired wave. This device includes a first signal having a desired wave as a center frequency and passing through a filter in a first band and a second signal having a desired wave as a center frequency and passing through a filter in a second band narrower than the first pass band. And a third adjacent signal which is higher than the desired signal and a third adjacent signal which has passed through a filter of a third band whose center frequency is lower than the desired wave and whose upper limit is lower than the center frequency of the desired wave. A second adjacent interference detection unit that obtains the sum of the fourth signal that has passed through the filter of the fourth band whose center frequency is the frequency and whose lower limit is higher than the center frequency of the desired wave, and the intensity ratio of the desired wave and the interference wave is When the intensity ratio is less than the predetermined threshold value, the interference wave is detected based on the output of the first adjacent interference detection unit when it is equal to or more than the predetermined threshold value, and based on the output of the second adjacent interference detection unit when the intensity ratio is less than the predetermined threshold value. And an interfering wave determining section for performing.

The second adjacent interference detector receives the input signal and smoothes the output of the first bandpass filter having the third passband and the first bandpass filter.
Smoothing means, a second bandpass filter having a fourth passband upon receiving the input signal, a second smoothing means for smoothing the output of the second bandpass filter, and
And an adding means for receiving and adding the output of the second smoothing means.

Another aspect of the present invention relates to a broadcast receiving device. This device, receiving means for converting a broadcast signal from a desired desired station to an intermediate frequency, and receiving the output of the receiving means,
Filter means for passing a signal having a bandwidth corresponding to the control signal, demodulation means for detecting and demodulating the output of the filter means, and adjacent interference in the peripheral frequency region of the desired wave based on the output of the receiving means. An adjacent interference detecting means for detecting a wave, wherein the adjacent interference detecting means has a first band whose center frequency is the desired wave and which has passed through a first band filter.
Of the first adjacent interference detection unit for obtaining the difference between the second signal having passed through the filter of the second band narrower than the first pass band with the desired frequency as the center frequency of the desired wave and the frequency lower than the desired wave A third band signal whose frequency is higher than the center frequency of the desired wave and whose upper limit is lower than the center frequency of the desired wave and a fourth band filter whose center frequency is higher than the desired wave and whose lower limit is higher than the center frequency of the desired wave. If the intensity ratio of the desired wave and the interference wave is equal to or greater than a predetermined threshold value, the second adjacent interference detection unit that obtains the sum of the passed fourth signal, and based on the output of the first adjacent interference detection unit, When the intensity ratio is less than the predetermined threshold value, it includes a disturbance wave determination unit that detects a disturbance wave based on the output of the second adjacent disturbance detection unit.

It is to be noted that any combination of the above constituent elements and the expression of the present invention converted between methods, devices, systems and the like are also effective as an aspect of the present invention.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 FIG. 1 is a schematic block diagram for explaining the configuration of an FM broadcast receiving apparatus 100 according to Embodiment 1.

Referring to FIG. 1, FM broadcast receiving apparatus 100
Is an antenna 10, a front end unit 12 that receives a signal from the antenna 10 and performs a tuning process, an amplification process, a conversion process to an intermediate frequency, and the like, and a front end unit 1.
IF filter 14 which is a band pass type filter which receives the output of 2 and passes the intermediate frequency signal of the desired band, and I
An FM detector 16 that receives the output of the F filter 14 and performs FM detection, and a stereo demodulator 18 that demodulates the detected signal and demodulates it into a stereo signal of an R signal and an L signal.
And an adjacent interference detection unit 200 which detects the DU ratio from the output of the front end unit 12 and gives a control signal to the IF filter 14, as will be described later.

Here, the front end section 12 is provided with an automatic gain control section (not shown), and an intermediate frequency signal (IF signal) output from the front end section regardless of the electric field strength at the receiving point. ) Is a constant level.

The present invention utilizes the property that if the output level of the interfering station is obtained, the level of the desired station that occupies the rest of the IF signal level can be known. As will be described later, the DU ratio that can be detected is obtained by utilizing the fact that the DU ratio, that is, the ratio between the desired wave signal level and the adjacent interfering wave signal level can be obtained depending on the detected output of the adjacent interfering station. It is possible to expand the range of.

Referring again to FIG. 1, the IF filter 14
Is based on the control signal from the adjacent interference detection unit 200,
The pass band is continuously or stepwise switched. For example, when the occurrence of an interfering signal is detected, the bandwidth of the IF filter 14 is reduced to a band capable of removing the interfering signal, and the output from the IF filter 14 having such a narrow bandwidth is detected. Can be When such control is performed, adjacent interference can be effectively prevented only when adjacent interference occurs, and when there is no adjacent interference, a good detection output for distortion can be obtained.

FIG. 2 is a block diagram of the adjacent interference detection unit 20 shown in FIG.
It is a schematic block diagram explaining the structure of 0.

The received signal converted from the antenna 10 to the intermediate frequency (IF) through the front end unit 12 is supplied to the first system adjacent interference detection unit 202 by the wide and narrow band difference system,
Second system adjacent interference detection unit 204 using adjacent band addition method
Given to.

The DU ratio determination unit 210 determines the DU ratio of the received signal based on the outputs from the first and second system adjacent interference detection units 202 and 204, and gives the determination result to the IF filter 14 as a control signal. .

FIG. 3 is a schematic block diagram for explaining the configuration of the first system adjacent interference detection unit 202 shown in FIG.

The first system adjacent interference detection unit 202 has a wide band pass filter 2022 having a wide pass band centering on the frequency of the desired station and a wide band band pass filter 2.
Smoothing processing unit 2024 for smoothing the output of 022
And a bandpass filter 2026 having a narrow passband around the frequency of the desired wave, and a smoothing processing unit 20 for smoothing the output of the narrowband bandpass filter 2026.
28 and a difference unit 2030 for calculating the difference between the outputs of the smoothing processing units 2024 and 2028.

The degree of interference is output from the difference unit 2030 and is provided to the DU ratio determination unit 210. As will be described later, the output of the subtractor 2030 is the first
System adjacent interference detector 202 and second system adjacent interference detector 2
The output of 04 can be normalized so as to continue at a predetermined threshold.

FIG. 4 shows the wideband bandpass filter 2022 and the narrowband bandpass filter 202 shown in FIG.
It is a figure which shows the passage characteristic of No. 6.

With the frequency F of the desired station as the center frequency, the pass band of the wide band pass filter has a pass band wide enough to include the interfering waves on both sides thereof.

On the other hand, the narrow band band pass filter has a narrow pass band centering on the frequency F of the desired station so as not to include the interfering wave. However, if the pass band width is narrowed up to this narrow band band pass filter, if the signal passed through such a narrow band band pass filter is detected by the detection circuit, the distortion factor will increase. In addition, it is not appropriate to use such a narrow band pass filter as the IF filter 14 of the FM receiver 100 when the degree of modulation is large.

FIG. 5 is a schematic block diagram for explaining the configuration of the second system adjacent interference detection unit 204 shown in FIG.

The second-system adjacent interference detection unit 204 includes a bandpass filter 2042 for detecting adjacent interference on the negative side, which has a pass band in the vicinity of an adjacent frequency on the lower side of the desired wave, and this bandpass filter filter. 2042
Smoothing processing unit 2044 for smoothing by receiving the output of
And a bandpass filter 2046 for detecting plus side adjacent interference, which has a pass band near the adjacent frequency on the higher frequency side from the desired station, and this bandpass filter 2046.
Smoothing processing unit 2048 for smoothing by receiving the output of
And an adder 2050 that receives the outputs of the smoothing processing units 2044 and 2048 and outputs a signal of the sum to the DU ratio determination unit 210. As will be described later, the output of the adder 2050 is also normalized so that the outputs of the first-system adjacent interference detection unit 202 and the second-system adjacent interference detection unit 204 continue at a predetermined threshold. can do.

FIG. 6 is a diagram showing pass band characteristics of the band pass filter 2042 for detecting the negative side adjacent interference and the band pass filter 2046 for detecting the positive side adjacent interference shown in FIG.

As shown in FIG. 6, the bandpass filter 2042 for detecting the negative side adjacent interference has a pass band in a region whose center frequency is a frequency lower than the frequency F of the desired station by Δf, and the upper limit of the pass band. Is less than the center frequency of the desired wave, and is set to a relatively narrow pass band so as not to include the desired wave. The bandpass filter 2046 for detecting the adjacent side interference on the plus side has a pass band in a region whose center frequency is a frequency higher by Δf than the frequency F of the desired station, and the lower limit of the pass band exceeds the center frequency of the desired wave. A relatively narrow pass band is set so that the desired wave is not included. These two bandpass filters 2042 and 2
In both 046, the pass band width is assumed to correspond to the area of the interference wave. For example, 100KH for European specifications
Since the channels are adjacent to each other in units of z, the value of Δf, which is the difference between the center frequency of the desired wave and the center frequency of the interfering wave to be detected, is 100 KHz.

FIG. 7 shows the first system adjacent interference detection unit 2 shown in FIG. 2 when intermodulation interference is received from an adjacent station.
9 is a diagram showing the DU ratio dependency of the difference value output from the No. 02, and FIG. 8 shows the output from the second system adjacent interference detection unit 204 shown in FIG. 2 when intermodulation interference from the adjacent station is received. It is a figure which shows the DU ratio dependence of the added value output performed.

As shown in FIG. 7, for example, the DU ratio is -3.
In the range of 0 to 0 dB, the first system adjacent interference detection unit 202
Although the output from the device accurately corresponds to the signal level of the interfering station, the output level sharply decreases when the DU ratio exceeds 0 dB, and the DU ratio cannot be accurately determined.

On the other hand, as shown in FIG. 8, the output from the second system adjacent interference detection unit 204 corresponds exactly to the signal level of the interference station even when the DU ratio is 0 to 30 dB.
On the contrary, if the DU ratio is 0 dB or less, the DU ratio cannot be accurately determined.

Therefore, in the determination of the DU ratio, the output result of the first system adjacent interference detection unit 202 by the wide and narrow band difference system is used in the range of the DU ratio of -30 to 0 dB and the DU ratio of 0 to +.
In the range of 30 dB, by using the output result of the second system adjacent interference detection unit 204 by the adjacent band addition method, it is possible to detect an excellent interference wave over a wide DU ratio range.

In other words, the DU ratio determining unit 210 operates in the first system adjacent interference detecting unit 2 in the first predetermined range of the DU ratio, for example, in the range of -30 to 0 dB as described above.
In the second predetermined range in which the DU ratio is larger than the first predetermined range, for example, in the range of 0 to +30 dB as described above, the second method adjacent interference is detected based on the output from 02. The interference wave is detected based on the output from the detection unit 204.

FIG. 9 shows the DU ratio determination unit 2 in this way.
FIG. 10 is a diagram showing the DU ratio dependency of the signal level which is the basis of the determination when the 10 detects the interference wave.

By using the characteristics of each of the first and second system adjacent interference detecting units 202 and 204 shown in FIGS. 7 and 8 by dividing them into regions, the detection range of the DU ratio can be expanded. At this time, which of the output values of the first and second system adjacent interference detection units 202 and 204 is to be used is determined by the output value from the first system adjacent interference detection unit 202 using the wide and narrow band difference system, for example.
This is performed based on the determination result of whether the U ratio is 0 or more.

FIG. 10 is a flow chart for explaining the operation of the adjacent interference detection unit 200 shown in FIG.

Referring to FIG. 10, first, when the DU ratio determination process is started (S100), it is determined whether or not the difference value by the wide and narrow band difference method exceeds the threshold value (S).
102).

If it exceeds the threshold value, the difference value of the wide and narrow band from the first system adjacent interference detection unit 202 is set to, for example, 1 to
The value normalized in the range of 0.5 is output as the DU ratio determination data by including it in the control signal (S104), and the process ends (S110).

On the other hand, when it is determined in step S102 that the wide / narrow band difference value does not exceed the predetermined threshold value, the output from the second system adjacent interference detection unit 204, that is, the determination value based on the adjacent band addition value. In response to this, the DU ratio determination unit 210 normalizes the output from the second system adjacent interference detection unit 204 to a value obtained by normalizing the output within the range of 0.5 to 0, for example.
It is output by including it in the control signal as the judgment data of the U ratio (S
106), the process ends (S110).

As described above, according to the present embodiment, the level of the interfering wave is determined within the predetermined range of the DU ratio based on the difference value of the signals passed through the wide band and narrow band band pass filters. , If the interfering wave becomes larger than this predetermined range, the level of the interfering wave is calculated based on the value obtained by adding the outputs from the two bandpass filters whose passbands are the adjacent bands on both sides of the desired wave. Therefore, it is possible to detect the state of adjacent interference over a wider range of DU ratios.

Embodiment 2 FIG. 13 is a block diagram showing an FM broadcast receiving apparatus 100 according to Embodiment 2.
It is a block diagram of. The configuration and operation different from those of the first embodiment will be described. DU output from the adjacent interference detection unit 200
The ratio data 15 is given to the IF filter 14 and the stereo demodulation unit 18.

FIG. 14 is a block diagram of the adjacent interference detection unit 200. The difference from the adjacent system interference detection unit 200 of the first embodiment is that a third system adjacent system interference detection unit 206 is provided and the output of the third system system adjacent interference detection unit 206 is provided to the DU ratio determination unit 210. The DU ratio determination unit 210 includes first, second and third adjacent interference detection units 202, 204 and 20.
6, the DU ratio of the received signal is determined, and the DU ratio data is sent to the IF filter 14 and the stereo demodulation unit 18.
Give to.

In the first embodiment, the detection range of the DU ratio can be expanded by the combination of the first system adjacent interference detection unit 202 and the second system adjacent interference detection unit 204. Is high, both the wide band narrow band difference value by the first method adjacent interference detection unit 202 and the adjacent band addition value by the second method adjacent interference detection unit 204 are large values even when there is no interference signal. And
It is erroneously determined that there is an interfering wave signal. Therefore, in the present embodiment, the third method adjacent interference detection unit 206 is provided so that the DU ratio can be detected more accurately in the range where the level of the interference wave is small.
Is further used to determine the DU ratio.

FIG. 15 shows the third system adjacent interference detection unit 206.
It is a block diagram of. The third-system adjacent interference detection unit 206 receives a negative-side adjacent interference detection bandpass filter 2062 in which the pass band is near the adjacent frequency on the lower frequency side of the desired wave, and the output of this bandpass filter 2062. A smoothing processing unit 2064 for smoothing, a bandpass filter 2066 for detecting positive side adjacent interference in which a pass band is in the vicinity of an adjacent frequency on the high frequency side from the desired station, and this bandpass filter 2066 A smoothing processing unit 2068 for receiving and smoothing an output, a differentiator 2070 for receiving the outputs of the smoothing processing units 2064 and 2068 and outputting a signal of the difference, and a differentiator 2070.
And an absolute value output unit 2072 that outputs the absolute value of the output of the above to the DU ratio determination unit 210. The difference unit 207
The output of 0 is the first system adjacent interference detection unit 202, the second system adjacent interference detection unit 204, and the third system adjacent interference detection unit 2.
It can be configured to normalize so that the output of 06 is continuous at a predetermined threshold value.

FIG. 16 is a diagram showing pass band characteristics of the band-pass filter 2062 for detecting the negative side adjacent interference and the band-pass filter 2066 for detecting the positive side adjacent interference shown in FIG. As shown in FIG. 16, the bandpass filter 2062 for detecting the negative side adjacent interference has a pass band in a region whose center frequency is a frequency lower than the frequency F of the desired station by Δf, and the upper limit of the pass band is the desired value. Although it is less than the center frequency of the wave, it is set to a relatively wide pass band so as to include some frequencies around the desired wave. Bandpass filter 20 for detecting adjacent interference on the plus side
66 has a pass band in a region whose center frequency is a frequency higher by Δf than the frequency F of the desired station, and the lower limit of the pass band exceeds the center frequency of the desired wave, but includes a peripheral frequency of the desired wave to some extent. In addition, a relatively wide pass band is set. The pass band width of each of these two band pass filters 2062 and 2066 is assumed to correspond to the region of the interference wave, and the pass band width is, for example, 1.5Δf.
Set to a moderate value. Or 7.5Δf to 2.25
You may set to the value of the range to (DELTA) f.

FIG. 17 shows the IF filter 1 shown in FIG.
It is a block diagram of FIG. The IF filter 14 switches the wide band IF filter 142, the middle band IF filter 144, and the narrow band IF filter 146 by the switch 148, passes the IF signal, and gives the IF signal to the FM detection unit 16. The switch 148 is switched according to the value of the DU ratio data 15. When the DU ratio is small, that is, when the level of the interference wave is high, the narrow band IF filter 146 having high selectivity.
When the DU ratio is large, that is, when the level of the interfering wave is low, the wideband IF filter 142 is switched to, and when the interfering wave is at an intermediate level, the intermediate band IF filter 144 is switched to.

FIG. 18 is a block diagram of the stereo demodulator 18 shown in FIG. The L-R sub-signal, L +, of the stereo composite signal FM-demodulated by the FM detector 16.
The R main signal is input to the stereo demodulation unit 18. L-
The R sub signal is amplified by the amplifier 180 and added to the adder 18
2 and the difference device 184. On the other hand, the L + R sub-signal is directly input to the adder 182 and the differencer 184.
The L signal is output from the adder 182, and the R signal is output from the difference unit 184. Here, the gain K of the amplifier 180 is D
It is adjusted according to the U ratio data 15. As a result, the degree of separation of the left and right channels in stereo sound changes, and separation control is performed according to the level of the interfering wave.

The L signal output from the adder 182 is input to the amplifier 191 having a gain α, and after passing through the low pass filter 186, is input to the amplifier 192 having a gain (1-α). Two amplifiers 191 and 19
The outputs from 2 are added by the adder 196 to finally output the L signal.

The R signal output from the adder 184 is input to the amplifier 193 having a gain α, and after passing through the low pass filter 188, is input to the amplifier 194 having a gain (1-α). Two amplifiers 193 and 19
The outputs from 4 are added by the adder 198 to finally output the R signal.

The values of the gain α of the four amplifiers 191 to 194 are adjusted according to the DU ratio data 15, and high cut control is performed. That is, when the level of the interfering wave is high, the gain α can be reduced to increase the weighting of the signals passed through the low-pass filters 186 and 188 to cut off the high frequency component.

FIG. 19 is a flow chart for explaining the DU ratio determination procedure by the adjacent interference detection unit 200 shown in FIG. First, when the DU ratio determination process is started (S20
0), it is determined whether or not the difference value by the narrow band difference method exceeds the first threshold value (S202). The first threshold value is set in advance as the value of the wide / narrow band difference value output from the first system adjacent interference detection unit 202 when the DU ratio corresponds to 0 dB, for example. When the wide / narrow band difference value exceeds the first threshold value (Y in S202), the DU ratio is 0 dB.
Can be determined to be less than, and the first system adjacent interference detection unit 2
The narrow band difference value from 02 is normalized to a range of 1 to 0.6, for example, and is output as DU ratio determination data (S2
04), and the DU ratio determination process ends (S212).

On the other hand, in step S202, if the wide / narrow band difference value does not exceed the first threshold value (N of S202), then it is determined whether or not the difference value by the adjacent band difference method exceeds the second threshold value. (S206). This second
The threshold is, for example, when the DU ratio corresponds to 30 dB,
It is preset as the adjacent band difference value output from the third system adjacent interference detection unit 206. The adjacent band difference value is the second
When the threshold is not exceeded (N of S206), the DU ratio is 3
It can be determined that it is equal to or higher than 0 dB, and the adjacent band difference value from the third system adjacent interference detection unit 206 is set to, for example, 0.
After being normalized to a range of 2 to 0, the data is output as DU ratio determination data (S210), and the DU ratio determination process is ended (S).
212).

On the other hand, in step S206, when the adjacent band difference value exceeds the second threshold value (Y in S206), it can be determined that the DU ratio is between 0 dB and 30 dB, and the second method adjacent interference The added value of the adjacent band from the detection unit 204 is normalized to, for example, the range of 0.6 to 0.2, and is output as the DU ratio determination data (S20).
8) Then, the DU ratio process ends (S212).

Embodiment 3 The configuration of FM broadcast receiving apparatus 100 according to Embodiment 3 is as follows:
This is the same as the second embodiment shown in FIG. 13, and the configuration of the adjacent interference detection unit 200 is the same as that of the first embodiment shown in FIG. The second system adjacent interference detection unit 204 includes a detection unit 204 and a DU ratio determination unit 210, and is different from the first embodiment.
It is the structure of. FIG. 20 shows the configuration of the second system adjacent interference detection unit 204 of this embodiment.

The second system adjacent interference detecting section 204 is a bandpass filter 2 for detecting negative adjacent interference in which the vicinity of the adjacent lower frequency side from the desired wave is the pass band.
082, a smoothing processing unit 2084 for receiving and smoothing the output of the band pass filter 2082, and a plus side adjacent interference detection for which a pass band is in the vicinity of an adjacent frequency on the higher frequency side from the desired station. Bandpass filter 20
86, a smoothing processing unit 2088 for smoothing by receiving the output of the band pass filter 2086, a differencer 2090 receiving the outputs of the smoothing processing units 2084 and 2088 and outputting the difference, and a differencer An absolute value output unit 2092 that outputs the absolute value of the output of 2090 to the DU ratio determination unit 210, and smoothing processing units 2084 and 2088.
And an adder 2094 that outputs the sum to the DU ratio determination unit 210. The difference device 20
The outputs of 90 and the adder 2094 can be configured to be normalized so that the outputs of the first-system adjacent interference detection unit 202 and the second-system adjacent interference detection unit 204 continue at a predetermined threshold.

This embodiment differs from the second embodiment in the following points. In the second embodiment, each of the second-system adjacent interference detection unit 204 and the third-system adjacent interference detection unit 206 has a bandpass filter for detecting the negative side adjacent interference and a band for the positive side adjacent interference detection, The two-system adjacent interference detection unit 204 calculates the adjacent band addition value, and the third-system adjacent interference detection unit 206 calculates the adjacent band difference value. In the present embodiment, the configurations of the bandpass filter and the smoothing processing unit are shared, and only the configuration of the second system adjacent interference detection unit 204 outputs both the adjacent band addition value and the adjacent band difference value.
As a result, the configuration of the adjacent interference detection unit 200 can be simplified. On the other hand, in the adjacent interference detection unit 200 of the second exemplary embodiment, a second method adjacent interference detection unit 204 that calculates an adjacent band addition value and a third method adjacent interference detection unit 206 that calculates an adjacent band difference value are used. The advantage is that the pass band and center frequency of the band pass filter can be made different.

Fourth Embodiment FIG. 21 is a block diagram of an adjacent interference detection unit 200 according to the fourth embodiment. In the present embodiment, the adjacent interference detection unit 20
0 includes the second system adjacent interference detection unit 204, the third system adjacent interference detection unit 206, and the DU ratio determination unit 210. Unlike the other embodiments, the first 0 calculates the wide / narrow band difference value.
The system adjacent interference detection unit 202 is not included. The configurations of the second system adjacent interference detection unit 204 and the third system adjacent interference detection unit 206 are the same as those in the second embodiment. In the present embodiment, the third method adjacent interference detection unit 206 of the adjacent band difference method is used.
However, it is characterized in that it is also used as a substitute for the first system adjacent interference detection unit 202 of the wide band differential system.

FIG. 22 is a flow chart for explaining the DU ratio determination procedure by the adjacent interference detection unit 200 according to this embodiment. First, when the DU ratio determination process is started (S
300), it is determined whether the difference value by the adjacent band difference method exceeds the first threshold value (S302). This first threshold value is the third threshold value when the DU ratio corresponds to 0 dB, for example.
It is set in advance as the value of the adjacent band difference value output by the system adjacent interference detection unit 206. Adjacent band difference value is first
When the threshold is exceeded (Y in S302), the DU ratio is 0d
It is possible to determine that it is less than B, the adjacent band difference value from the third system adjacent interference detection unit 206 is normalized to, for example, a range of 1 to 0.6, and output as DU ratio determination data (S
304), and the DU ratio determination process ends (S312).

On the other hand, in step S302, when the adjacent band difference value does not exceed the first threshold value (N in S302), it is next determined whether or not the adjacent band difference value exceeds the second threshold value (S306). ). The second threshold value is set in advance as an adjacent band difference value output by the third system adjacent interference detection unit 206 when the DU ratio corresponds to, for example, 30 dB. When the adjacent band difference value does not exceed the second threshold value (N of S306), it can be determined that the DU ratio is 30 dB or more, and the third system adjacent interference detection unit 20.
The adjacent band difference value from 6 is normalized to a range of 0.2 to 0, for example, and is output as DU ratio determination data (S3
10) and the DU ratio determination process ends (S312).

On the other hand, in step S306, when the adjacent band difference value exceeds the second threshold value (Y in S306), it can be determined that the DU ratio is between 0 dB and 30 dB, and the second method adjacent interference The added value of the adjacent band from the detection unit 204 is normalized to a range of, for example, 0.6 to 0.2, and then output as DU ratio determination data (S30).
8), the DU ratio process ends (S312).

In this embodiment, since the wide band differential type adjacent interference detecting unit is not included, the adjacent interference detecting unit 20
The configuration of 0 can be simplified.

As described above, in any of the embodiments, by selecting the calculation outputs from a plurality of adjacent interference detection units according to the DU ratio by the configuration of the adjacent interference detection unit 200, a wide DU ratio can be obtained. It is possible to accurately determine the level of adjacent interference over the range.

The present invention has been described above based on the embodiments. It is understood by those skilled in the art that these embodiments are mere examples, and that various modifications can be made to the combinations of the respective constituent elements and the respective processing processes, and that such modifications are also within the scope of the present invention. By the way. Each component is illustrated as a functional block, and those skilled in the art will understand that these functional blocks can be realized in various forms by only hardware, only software, or a combination thereof. The adjacent interference detection unit in any of the embodiments can be integrated into an LSI to be a single device, and this may be used by being incorporated in an FM receiver or the like.

[0086]

According to the present invention, the level of adjacent interference can be accurately detected in a wider DU ratio range.

[Brief description of drawings]

FIG. 1 is a schematic block diagram for explaining a configuration of an FM broadcast receiving apparatus according to a first embodiment.

2 is a schematic block diagram illustrating a configuration of an adjacent interference detection unit illustrated in FIG.

FIG. 3 is a schematic block diagram for explaining a configuration of a first system adjacent interference detection unit of FIG.

FIG. 4 is a diagram showing pass characteristics of the wideband bandpass filter and the narrowband bandpass filter of FIG. 3;

5 is a schematic block diagram for explaining a configuration of a second system adjacent interference detection unit of FIG.

FIG. 6 is a diagram showing pass band characteristics of the two band pass filters of FIG.

FIG. 7 is a diagram showing the difference value D output from the first system adjacent interference detection unit when intermodulation interference is received from an adjacent station.
It is a figure which shows U ratio dependence.

FIG. 8 is a diagram showing an addition value D output from the second system adjacent interference detection unit when intermodulation interference is received from an adjacent station.
It is a figure which shows U ratio dependence.

FIG. 9 is a diagram showing the DU ratio dependency of the signal level which is the basis of the judgment when the DU ratio judgment unit of FIG. 2 detects an interference wave.

FIG. 10 is a flowchart illustrating a DU ratio determination procedure by the adjacent interference detection unit according to the first embodiment.

FIG. 11 is a conceptual diagram for explaining intermodulation.

FIG. 12 is a conceptual diagram showing the effect of intermodulation interference when there is a jamming station in an FM receiver or the like.

FIG. 13 is a configuration diagram of an FM broadcast receiving device according to a second embodiment.

14 is a configuration diagram of an adjacent interference detection unit of FIG.

15 is a configuration diagram of a third system adjacent interference detection unit of FIG.

16 is a diagram showing pass band characteristics of the two band pass filters of FIG.

FIG. 17 is a configuration diagram of the IF filter of FIG. 13.

18 is a configuration diagram of a stereo demodulation unit in FIG.

FIG. 19 is a flowchart illustrating a DU ratio determination procedure performed by the adjacent interference detection unit according to the second embodiment.

FIG. 20 is a second part of the adjacent interference detection unit according to the third embodiment.
It is a block diagram of a system adjacent interference detection unit.

FIG. 21 is a configuration diagram of an adjacent interference detection unit according to the fourth embodiment.

FIG. 22 is a flowchart illustrating a DU ratio determination procedure by the adjacent interference detection unit according to the present embodiment.

[Explanation of symbols]

10 antenna, 12 front end part, 14
IF filter, 16FM detection unit, 18 stereo demodulation unit, 100 FM broadcast receiving device, 200 adjacent interference detection unit, 202 first system adjacent interference detection unit, 20
4 2nd type | system | group adjacent disturbance detection part, 206 3rd type | system | group adjacent disturbance detection part, 210 DU ratio determination part.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaaki Hira             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. F-term (reference) 5K020 AA04 DD03 EE04 EE16 HH15                       KK07 NN01                 5K042 BA06 CA02 CA12 DA01 DA20                       FA11                 5K052 AA03 BB04 CC04 DD04 EE04                       EE11

Claims (12)

[Claims] 1. A first detection unit that outputs a difference value of signal outputs that have passed through two band filters having different pass bands centered on the frequency of the desired wave, and a frequency higher and lower than the frequency of the desired wave. A second detection unit that outputs an added value of signal outputs that have passed through two bandpass filters each having a center frequency, and the first and second detection units according to the output level of an interfering wave generated adjacent to the desired wave. An adjacent interference detection device comprising: an intensity ratio determination unit that selects an output value of any one of a plurality of detection units including a detection unit and determines an intensity ratio of the desired wave and the interference wave. 2. The intensity ratio determination unit further includes a third detection unit that outputs a difference value of signal outputs that have passed through two bandpass filters whose center frequencies are frequencies higher and lower than the frequency of the desired wave, respectively. The adjacent interference according to claim 1, wherein the intensity ratio is determined by selecting an output value of any one of a plurality of detection units including the first, second, and third detection units. Detection device. 3. The strength detection circuit further outputs a difference value between signal outputs that have passed through the two band-pass filters whose center frequencies are frequencies higher and lower than the frequency of the desired wave, respectively. The unit is a difference value output from the first detection unit,
The adjacent interference detection device according to claim 1, wherein the intensity ratio is determined by selecting one of the addition value and the difference value output from the second detection unit. 4. A first detection unit that outputs an added value of signal outputs that have passed through two band-pass filters whose center frequencies are frequencies higher and lower than the frequency of the desired wave, and a frequency higher than the frequency of the desired wave. And a second detection unit that outputs a difference value of signal outputs that have passed through two band-pass filters each having a low frequency as a center frequency, and the second detection unit according to an output level of an interfering wave generated adjacent to the desired wave. An adjacent interference detection device comprising: an intensity ratio determination unit that selects an output value of one of the first and second detection units and determines the intensity ratio of the desired wave and the interference wave. 5. A front end section for converting an FM broadcast signal received from a desired station into an intermediate frequency signal, and an adjacent interference detection section for detecting the intensity of an interference wave adjacent to a desired wave based on the intermediate frequency signal. An intermediate frequency filter unit for filtering the intermediate frequency signal with a bandpass filter according to the intensity of the interfering wave and outputting the FM signal; and an FM based on the output signal from the intermediate frequency filter unit.
An FM detection unit that outputs a demodulation signal, and a stereo demodulation unit that stereo-demodulates and outputs the FM demodulation signal, and the adjacent interference detection unit is a signal of the interference wave in a peripheral frequency region of the frequency of the desired wave. Are detected by different methods to detect and output the output level of the interfering wave, and an output value of any one of the plurality of detecting sections is selected according to the output level of the interfering wave. And a strength ratio determination unit that determines a strength ratio between the desired wave and the interfering wave. 6. The first detection unit outputs a difference value of signal outputs that have passed through two band-pass filters having different pass bands centering on the frequency of the desired wave, and a frequency of the desired wave. The broadcast receiving device according to claim 5, further comprising: a second detection unit that outputs an added value of signal outputs that have passed through two band-pass filters each having a higher frequency and a lower frequency as a center frequency. 7. The third detection unit further includes a third detection unit that outputs a difference value of signal outputs that have passed through two band-pass filters whose center frequencies are frequencies higher and lower than the frequency of the desired wave, respectively. The broadcast receiving apparatus according to claim 6, comprising: 8. The broadcast receiving apparatus according to claim 5, wherein the stereo demodulation unit adjusts the degree of separation of left and right channels in stereo sound according to the intensity ratio. 9. The broadcast receiving apparatus according to claim 5, wherein the stereo demodulation unit changes a ratio of removing a high frequency component of the FM demodulated signal according to the intensity ratio. . 10. A first detection step of outputting a difference value of signal outputs passing through two band filters having different pass bands centering on a frequency of a desired wave, and a frequency higher and a frequency lower than the frequency of the desired wave, respectively. A second detection step of outputting an added value of signal outputs that have passed through two band-pass filters having a center frequency; and a second detection step if the output level of an interfering wave generated adjacent to the desired wave is higher than a predetermined threshold value. When the output level of the interfering wave is lower than the predetermined threshold value using the difference value of the first detecting step, the intensity ratio between the desired wave and the interfering wave is determined using the added value of the second detecting step. And a determination step for performing the adjacent interference detection method. 11. The method further comprises a third detection step of outputting a difference value of signal outputs that have passed through two band-pass filters each having a center frequency of a frequency higher than the frequency of the desired wave and a frequency lower than the frequency of the desired wave. The output level of the interfering wave is divided into three levels, the difference value of the first detection step is used in the range where the output level is high, and the difference value of the third detection step is used in the range where the output level is low. 11. The adjacent interference detection method according to claim 10, wherein the intensity ratio is determined using the added value of the second detection step in the other intermediate range. 12. A first detection step of outputting a sum of signal outputs that have passed through two band-pass filters each having a center frequency of a frequency higher than a frequency of a desired wave and a frequency higher than a frequency of the desired wave. And a second detection step of outputting a difference value of signal outputs that have passed through two band-pass filters each having a low frequency as a center frequency, and an output level of an interfering wave generated adjacent to the desired wave is set to 3
Dividing into stages, in the high and low output level ranges, based on the difference value in the second detection step,
In the other intermediate range, the adjacent interference detection method includes a determination step of determining the intensity ratio of the desired wave and the interference wave based on the added value of the first detection step.