JP2523416B2 - FM radio receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double superheterodyne FM having a first intermediate frequency amplifying stage and a second intermediate frequency amplifying stage having a frequency band narrower than that of the first intermediate frequency amplifying stage. Radio receiver, second
The present invention relates to a device provided with an adaptive tracking filter FM demodulation device capable of reducing interference by changing the center frequency and selectivity of the intermediate frequency amplification stage, particularly when the reception condition of the selected radio wave is good. The present invention relates to an FM radio receiver that automatically selects and demodulates the output of the first intermediate frequency amplification stage having a wide frequency band, and reproduces the audible sound.

[0002]

2. Description of the Related Art A double superheterodyne FM radio receiver having an adaptive tracking filter FM demodulator in a second intermediate frequency amplification stage is known. The adaptive tracking filter FM demodulation device changes the center frequency of the filter of the second intermediate frequency amplification stage according to the modulation displacement of the selected signal, and the second intermediate frequency amplification according to the level of interference from the adjacent station. By changing the stage selectivity, interference from adjacent stations is reduced.

An FM radio receiver equipped with this adaptive tracking filter FM demodulator is extremely effective for receiving a desired station in a region where broadcasting stations are close to each other, such as Europe.

In a portable or vehicle-mounted receiver, radio waves from a distant broadcasting tower may reach and be disturbed while moving in a mountainous area. In such a case, adaptive tracking is also performed. The filter FM demodulator has a great effect.

FIG. 3 shows a conventional double superheterodyne type F equipped with an adaptive tracking filter FM demodulator.
It is a whole block block diagram of an M radio receiver. Conventional F
The M radio receiver 101 amplifies the signal received by the receiving antenna 2 by the high frequency signal amplifier circuit 3, and outputs the output signal 3a.
And the first local oscillation frequency signal 4a generated in the first local oscillation circuit 4 are mixed in the first mixing circuit 5 and, for example, the frequency 1
A first intermediate frequency signal 5a of 0.7 MHz is generated, this signal 5a is amplified by a first intermediate frequency amplification stage 6 equipped with a fixed pass band type intermediate frequency filter 7 having a predetermined frequency bandwidth, and the amplification thereof. The output 6a is supplied to the adaptive tracking filter FM demodulation device 120.

Then, the adaptive tracking filter FM
The demodulation output 140a of the demodulation device 120 is input to the frequency-multiplexed signal demodulation circuit 7 such as a stereo signal demodulation circuit, and in the case of stereo broadcasting reception, left and right channel audio signals 7L,
7R is obtained, and in the case of frequency-division multiplex broadcasting, a signal selection circuit (not shown) is used to switch between the traffic information broadcast on the sub-channel, the information related to the identification code of the broadcasting station, and the broadcasting of the main channel. Go, each of these audio signals 7
L and 7R (which may include digital signals) are power-amplified by the low-frequency amplifiers 8L and 8R, and the electroacoustic transducers 9L and 9R such as speakers are driven to reproduce audible sound. Further, the audio signals 7L and 7R are configured so as to be supplied to other devices from an output section (not shown).

FIG. 4 is a block diagram of a conventional adaptive tracking filter FM demodulator. The adaptive tracking filter FM demodulation device 120 includes an AGC circuit 2
1, a second local oscillation circuit 22, a second mixing circuit 23,
It includes a second intermediate frequency amplification stage 130 and a second intermediate frequency signal demodulation unit 140.

The second intermediate frequency amplification stage 130 includes an adaptive tracking filter circuit 31 and a tracking control circuit 3.
2, an AGC control circuit 33, a reception station signal level detection circuit 34, an adjacent station signal extraction circuit 35, an adjacent station signal level detection circuit 36, an adjacent interference detection circuit 37, and a pass band control circuit 38. .

The second intermediate frequency signal demodulation section 140 includes a second intermediate frequency signal demodulation circuit 141 and a frequency characteristic correction circuit 14.
2 and an amplitude limiting circuit 143.

The AGC circuit 21 outputs the amount of amplification or attenuation of the AGC signal 3 output from the AGC control circuit 33.
3a, and the level of the first intermediate frequency signal 21a supplied to the second mixing circuit 23 is made substantially constant.

The second local oscillator circuit 22 has, for example, a frequency of 1
Generate a second local oscillation frequency signal 22a of 0 MHz,
It is supplied to the second mixing circuit 23. The second mixing circuit 23 mixes the level-adjusted first intermediate frequency signal 21a and the second local oscillation frequency signal 22a so that the intermediate frequency is, for example, 7
It is converted to the second intermediate frequency signal 23a of 00 KHz. The second intermediate frequency signal 23 a is input to the second intermediate frequency amplification stage 130 including the adaptive tracking filter circuit 31.

The adaptive tracking filter circuit 31 includes
It has a function of continuously varying the center frequency of the filter and a function of switching the pass band width with respect to the center frequency in, for example, six stages.

The filter center frequency can be changed by changing the capacitance of a plurality of variable capacitance diodes provided in the filter circuit based on the tracking control voltage signal 32a for controlling the center frequency output from the tracking control circuit 32. Done.

The switching of the pass band width is performed by the pass band designation information (for example, parallel 5) output from the pass band control circuit 38.
It is performed by changing the resistance value for selectivity adjustment connected in parallel to the coil in the filter circuit based on the bit information) 38a.

This adaptive tracking filter circuit section 3
1 has four sets of filter circuits connected in series.
The center-frequency tracking control is mainly performed in the filter circuit section of the second stage, and the pass band width is mainly switched in the filter circuit section of the latter two stages.

Further, the adaptive tracking filter circuit section 31 outputs a signal which has passed through the filter circuits of the previous two stages from the terminal 31a, and outputs a signal which is output from the terminal 31b through the filter units of the front and rear two stages. It is configured to switch between the selected signal and the signal that has passed only the filter units of the previous two stages based on the filter stage number designation information included in the pass band designation information 38a.

The second intermediate frequency signal demodulation circuit 141 demodulates the second intermediate frequency signal 130a output from the output terminal 31b of the adaptive tracking filter circuit 31. The demodulated detection output 141a is sent to the tracking control circuit 32.
Is supplied to the frequency characteristic correction circuit 42 and the adjacent interference detection circuit 37.

The tracking control circuit 32 detects the detection output 4
A high-frequency emphasizing circuit for emphasizing the high-frequency component of 1a, a phase inverting circuit for generating a signal obtained by inverting the phase of the output signal of the high-frequency emphasizing circuit, and a smoothing circuit for smoothing the phase-inverted output with a predetermined time constant. And outputs the smoothed output as the tracking control voltage signal 32a.

Further, the tracking control circuit 32 is
The tracking operation mode in which the tracking control voltage is varied according to the detection output 41a and the tracking stop mode in which a preset fixed voltage related to the center frequency designation of the filter is output are set to the tracking on / off control signal 38.
It is configured to switch based on b.

Further, in the tracking operation mode, the tracking control circuit 32 allows a wide range of frequencies in which the center frequency of the filter is varied according to the detection output 41a based on the tracking range switching signal 38c. It is configured to switch to a relatively narrow range. The tracking range is switched by adjusting the gain of the feedback control loop based on the tracking range switching signal 38c.

The frequency characteristic correction circuit 142 is provided with a peaking circuit for emphasizing the high frequency component of the detection output 141a of the second intermediate frequency signal narrowed by the adaptive tracking filter circuit 31. The high frequency component of the main channel signal and the sub channel signal are emphasized.
The peaking frequency is the frequency of the subcarrier (US 6
7 KHz, Europe 57 KHz, Japanese stereo broadcasting 38 K
(Hz, etc.) is generally used.

Detection output 142 whose frequency characteristic is corrected
a is a decoding output signal (MP
XOUT). It should be noted that this amplitude limiting circuit 143, based on the amplitude limiting on / off signal 38d,
When the degree of adjacent interference, which will be described later, is large and the detected output is excessive, the amplitude limiting operation is performed to suppress the excessive output.

The AGC control circuit 33 performs an envelope detection circuit 33b for performing an envelope detection of the relatively wide band second intermediate frequency signal output from the intermediate output terminal 31a of the adaptive tracking filter circuit 31. And the envelope detection output 33c is smoothed with a predetermined time constant to obtain the AGC signal 3
A smoothing circuit 33d for generating 3a is provided. AGC signal 3
3a is supplied to the AGC circuit 21 and the reception station signal level detection circuit 34, and the envelope detection output 33c is supplied to the adjacent station signal extraction circuit 35.

The receiving station level detecting circuit 34 supplies information 34a, 34b relating to the receiving level of the receiving station (desired station) to the pass band control circuit 38 based on the AGC signal 33a. By providing two sets of voltage comparators having different value voltages and outputting the comparison output of each comparator as information 34a, 34b relating to the magnitude of the reception level, the level of the reception signal can be divided into three stages of large, medium and small. I am configuring.

The adjacent station signal extraction circuit 35 includes a high pass filter (HPF) 35a, an envelope detection circuit 35b, and a smoothing circuit 35c. The high-frequency component is extracted from the detection output 33c of the envelope detection circuit 33b in the AGC control circuit 33 via the high-pass filter 35a, and the extracted high-frequency component is again envelope-detected by the envelope detection circuit 35b. By smoothing by the smoothing circuit 35c, the voltage output 35d corresponding to the level of the signal adjacent to the receiving station (desired station) is obtained.

The adjacent station level detection circuit 36, based on the voltage output 35d from the adjacent station signal extraction circuit 35, information 36a, 36b, 36 relating to the magnitude of the reception level of the adjacent station.
c and 36d are supplied to the pass band control circuit 38,
For example, four sets of voltage comparators having different threshold voltages are provided, and the comparison output of each comparator is output as the information 36a to 36d relating to the magnitude of the interfering signal level, whereby the level of the interfering signal by the signal of the adjacent station is obtained. Is divided into 5 stages.

The adjacent interference detection circuit 37 includes a low pass filter (LPF) 37a for extracting frequency components below the subcarrier frequency from the detection output 41a demodulated by the second intermediate frequency signal demodulation circuit 41, The low-pass filter (LPF) 37a is provided with an interference sound detection circuit 37b which generates a logical output 37c for adjacent interference detection when the output exceeds a preset threshold level. The disturbing sound detection circuit 37b is composed of a voltage comparator having a preset threshold voltage. The interference sound detection output 37c is supplied to the pass band control circuit 38.

The pass band control circuit 38 includes information 34a, 34b relating to the signal level of the receiving station (desired station),
Information 36a to 36d relating to (interference) signals of adjacent stations and the adjacent interference detection output 37c are used as control inputs, and information 38a designating the pass band of the adaptive tracking filter circuit 31 and ON / OFF of the tracking operation are set. The designated signal 38b and the tracking range switching signal 38c
And the amplitude limiting on / off signal 38d are output based on preset conditions.

FIG. 5 is an explanatory view showing the pass band variable characteristic of the adaptive tracking filter circuit which is the second intermediate frequency filter. This adaptive tracking filter circuit 31
Can switch between six types of pass band widths A to F based on the pass band designation information 38a as shown in FIG. Then, as shown in FIG. 5B, the pass band control circuit 38 sets the signal level (electric field strength) of the receiving station (desired station) and the interference wave level (electric field strength of the interference wave) from the adjacent station. Based on the S / N of the received signal, the control is performed so as to narrow the pass band of the second intermediate frequency signal as the interference increases.

When the adjacent interference detection output 37c is input, the pass band control circuit 38 outputs information 34a and 34b relating to the signal level of the receiving station in that state and information 36a to 36d relating to the receiving level of the adjacent station. Compare. Then, when the level of the adjacent station signal is higher than the level of the receiving station signal by a preset level or more, a signal 38b for controlling the tracking operation to the off state is output to stop the tracking operation, thereby The center frequency of the tracking filter circuit 31 is prevented from shifting to the adjacent station side where the signal level is large, and the signal 38d relating to the ON of the amplitude limitation is output, so that the decoding output signal 40a becomes excessive due to the adjacent interference output. Suppress.

Further, in the pass band control circuit 38, the signal levels 36a to 36d of the adjacent stations are changed to the signal level 34 of the receiving station.
When it is sufficiently lower than a and 34b (when interference is not received), the tracking range switching signal 38c is output so as to widen the tracking range.

With the above-mentioned configuration, the conventional FM radio receiver 101 selects a relatively wide predetermined band in the first intermediate frequency amplification stage 6 of fixed pass band type, and further includes the adaptive tracking filter 31. Second intermediate frequency amplification stage 3 used
Since 0 narrows the pass band according to the degree of adjacent interference,
Interference from adjacent stations can be greatly reduced.

[0033]

As described above,
The conventional double-super-heterodyne FM radio receiver 101 has a configuration in which the second intermediate frequency amplification stage 130 is used to narrow the pass band of the signal and improve the selectivity.
Detection output 14 demodulated by the second intermediate frequency signal demodulation circuit 41
Even if the high frequency component of 1a is emphasized by the frequency characteristic correction circuit 42 including the peaking circuit, the frequency characteristic of the detection output 141a is different from that of the original signal, and therefore, even in a good reception state where no adjacent interference is received. , The fidelity of the reproduced sound is reduced.

Further, since the frequency characteristic correction circuit 142 is configured to emphasize the high frequency component, when the modulation frequency of the received signal is high (the high frequency component of the audio signal is large), the harmonics generated by demodulation are generated. The frequency component of becomes high, and the harmonic component reaches the peaking frequency range. Therefore, the frequency characteristic correction circuit 142 emphasizes the originally unnecessary noise component, and the distortion rate of the decoding output signal MPXOUT decreases,
The fidelity of the reproduced sound is impaired.

The present invention has been made in order to solve such a problem, and an object thereof is to provide an FM radio receiver capable of high-fidelity reproduction in a good reception state in which adjacent interference is not received. To do.

[0036]

In order to solve the above problems, an FM radio receiver according to the present invention includes an inverse conversion circuit for inversely converting an output signal of a second intermediate frequency amplification stage into a signal of a first intermediate frequency, An intermediate frequency signal demodulation circuit by selecting one of two intermediate frequency signals, the narrow band intermediate frequency signal inversely converted by the inverse conversion circuit and the wide band intermediate frequency signal output from the first intermediate frequency amplification stage. To the intermediate frequency signal selection circuit, a receiving station signal level detection circuit for detecting the signal level of the receiving station based on the signal component of the second intermediate frequency signal of the second intermediate frequency amplification stage, and a second intermediate frequency amplification stage An adjacent station signal level detection circuit for detecting the signal level of the adjacent station based on the high frequency signal component of the second intermediate frequency signal of, and the signal level of the receiving station is higher than a preset received signal level and Signal The intermediate frequency signal selection control means for controlling the intermediate frequency signal selection circuit so as to select the wideband intermediate frequency signal in a receiving state in which the signal is smaller than the preset interference signal level and the narrowband intermediate frequency signal in other receiving states. It is characterized by that.

[0037]

[Operation] In a good reception condition without interference,
The first intermediate frequency signal having a wide pass band is automatically selected and the signal is supplied to the demodulation circuit. Therefore, it is possible to perform reproduction with high fidelity in a good reception state in which no adjacent interference is received.

Further, since the narrow band second intermediate frequency signal (for example, 700 KHz) is converted into the signal of the first intermediate frequency (for example, 10.7 MHz) by the inverse conversion circuit, the intermediate frequency for the first intermediate frequency is used. The signal demodulation circuit can demodulate wideband and narrowband intermediate frequency signals.

[0039]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall block diagram of an FM radio receiver according to the present invention, and FIG. 2 is a block diagram of an adaptive tracking filter FM demodulator having a built-in intermediate frequency signal selection function. FM radio receiver 1 according to the present invention
In the adaptive tracking filter FM demodulation device 20, the intermediate frequency signal selection function is incorporated.

The adaptive tracking filter FM demodulator 20 having a built-in intermediate frequency signal selection function is different from the conventional adaptive tracking filter FM demodulator 120 shown in FIGS. 4 and 4 in the second intermediate frequency amplification stage 30. Output 3
Inverse conversion circuit 2 for inversely converting 0a into a signal of the first intermediate frequency
4, a first intermediate frequency signal amplification circuit 25 for amplifying the output signal 6a of the first intermediate frequency amplification stage 6, an intermediate frequency signal selection circuit 26 for selecting one of the inverse conversion output 24a and the amplified output 25a, Each signal detection output 34a of the reception station signal level detection circuit 34 and the adjacent station signal level detection circuit 36 in the adaptive tracking filter FM demodulation device 20,
Intermediate frequency signal selection control means 2 for generating the intermediate frequency signal selection control signal 27a based on 34b and 36a to 36d.
7 and an intermediate frequency demodulation unit 40 are newly provided.

The inverse conversion circuit 24 includes the second intermediate frequency amplification stage 3
The output signal 30a of 0 (for example, 700 KHz) is mixed with the second local oscillation frequency signal (for example, 10 MHz) supplied from the second local oscillation circuit 22, and the sum of these signal frequencies (for example, 10.7 MHz) The signal, that is, the signal 24a of the first intermediate frequency is generated. The first intermediate frequency signal 24 a is a narrow band intermediate frequency signal whose pass band is narrowed by the second intermediate frequency amplification stage 30.

The first intermediate frequency signal 6a selected by the first intermediate frequency amplification stage 6 to have a relatively wide predetermined pass band is AGC.
It is supplied to both the circuit 21 and the first intermediate frequency amplifier circuit 25. The first intermediate frequency amplifying circuit 25 uses the first intermediate frequency signal 6
a is amplified to a predetermined level set in advance.

The intermediate frequency signal selection circuit 26 includes an intermediate frequency signal selection control signal 2 applied to the selection control input terminal 26c.
When 7a is, for example, H level, one signal input terminal 26
The output signal 25a of the first intermediate frequency signal amplification circuit 25 supplied to a is selected, and for example, in the case of L level, the conversion output signal 24a of the inverse conversion circuit 24 supplied to the other signal input terminal 26b is selected. The selection output terminal 26d is supplied to the intermediate frequency signal demodulation circuit 40.

The intermediate frequency signal selection control means 27 outputs a detection output 30a indicating that the reception signal level is equal to or higher than a preset reception signal level to the reception station signal level detection circuit 3
4 and each of the detection output signals 36a to 36d which indicate the interference signal level from the adjacent station level detection circuit 36.
Is not output, it is determined that the receiving station has a strong electric field strength and is not receiving interference from an adjacent station, and for example, the H level intermediate frequency signal selection control signal 27a. Is configured to output.

The second intermediate frequency amplification stage 30 is basically the same as that shown in FIG. 4, and each signal level detection circuit 3
The detection outputs 34a, 36a to 36d of 4, 36 are taken out and supplied to the intermediate frequency signal selection control means 27.

As shown in FIG. 2, the intermediate frequency signal demodulation unit 4
0 consists of an intermediate frequency signal demodulation circuit 41, a frequency characteristic correction circuit 42, and an amplitude limiting circuit 43.

The intermediate frequency signal demodulation circuit 41 includes an intermediate frequency signal 24a having a first intermediate frequency (for example, 10.7 MHz),
25a is demodulated.

The frequency characteristic correction circuit 42 is constructed so that it can be switched whether or not to correct the frequency characteristic according to the level of the logic signal supplied to the control input terminal 42a. When the intermediate frequency signal selection control output 27a of the means 27 specifies the selection of the first intermediate frequency signal 25a (for example, at the H level), the frequency characteristic correction for emphasizing the high frequency component is not performed. are doing.

The reception condition is good and the first intermediate frequency signal 25a
When the side is selected, the adjacent interference detection circuit 37 does not generate the adjacent interference detection output 37c. Therefore, based on the adjacent interference detection output 37c, the pass band control circuit outputs the control signal 38d for turning on the amplitude limitation. Is the amplitude limiting circuit 4
However, when the intermediate frequency signal selection control output 27a of the intermediate frequency signal selection control means 27 designates the selection of the first intermediate frequency signal 25a (for example, at the H level), the amplitude limitation is performed. The amplitude limiting operation of the circuit 43 may be controlled to a non-operating state to prevent malfunction or the like.

Further, a logic circuit or the like for generating the intermediate frequency signal selection control signal 27a may be provided in the pass band control circuit 38 without providing the intermediate frequency signal selection control means 27 alone, or a new logic is provided. The first intermediate frequency signal 25a may be selected when the passband designation information 38a outputs, for example, the information designating the band A shown in FIG. 5 without providing a circuit section or the like.

As described above, the FM radio receiver 1 according to the present invention uses the first intermediate frequency signal 25a and the second intermediate frequency amplification stage by the inverse conversion circuit 24 based on the signal levels of the receiving station and the adjacent station. Second with narrow pass band at 30
The intermediate frequency signal is automatically switched to the first intermediate frequency signal 24a.

Therefore, when the reception level of the receiving station (desired station) is high and the reception state is good without interference, the first intermediate frequency signal signal 25a is demodulated by the intermediate frequency signal demodulating section 40 and reproduced. In addition to automatically performing reproduction with a wide band and high fidelity, when interference is generated by a signal from an adjacent station, the second intermediate frequency amplification stage 30 narrows the pass band to improve the selection of the signal 24a. Since demodulation is performed by the intermediate frequency amplification stage 40, interference interference can be reduced.

Further, the inverse conversion circuit 24, the first intermediate frequency signal amplification circuit 25, the intermediate frequency signal selection circuit 26, and the intermediate frequency signal selection control means 27 are provided in the adaptive tracking filter FM demodulation device 20. Thus, the detection outputs 34a, 34b of the reception station signal level detection circuit 34 and the adjacent station signal level detection circuit 36 for pass band control are provided.
36a to 36d can be effectively used as input signals for selecting the intermediate frequency signal.

Since the additional circuit scale is relatively small, the conventional integrated circuit for the adaptive tracking filter FM demodulator 120 is improved to create a dedicated integrated circuit for the single / double superheterodyne automatic switching system. It is also relatively easy to do.

[0055]

As described above, the FM according to the present invention
The radio receiver outputs the output signal of the first intermediate frequency amplification stage having a wide signal pass band and the second intermediate frequency signal of the second intermediate frequency amplification stage having a narrower signal pass band than the first intermediate frequency amplification stage to the first intermediate frequency. The signal of the receiving station is provided based on each detection output of the receiving station level detecting circuit and the adjacent station signal level detecting circuit. When the level is large and the signal level of the adjacent station is small and there is no interference, the output signal of the first intermediate frequency amplification stage is selected. One intermediate frequency signal is selected, and reproduction with a wide reproduction frequency band and high fidelity can be automatically performed.

[Brief description of drawings]

FIG. 1 is an overall block configuration diagram of an FM radio receiver according to the present invention.

FIG. 2 is a block configuration diagram of an adaptive tracking filter FM demodulator having a built-in intermediate frequency signal selection function.

FIG. 3 is an overall block diagram of a conventional double superheterodyne FM radio receiver including an adaptive tracking filter FM demodulator.

FIG. 4 is a block configuration diagram of a conventional adaptive tracking filter FM demodulation device.

FIG. 5 is an explanatory diagram showing pass band variable characteristics of an adaptive tracking filter circuit that constitutes a second intermediate frequency amplification stage.

[Explanation of symbols]

1 ... FM radio receiver, 6 ... 1st intermediate frequency amplification stage, 20
... adaptive tracking filter FM demodulator, 24 ... Inverse conversion circuit, 25 ... First intermediate frequency signal amplification circuit, 25a ...
First intermediate frequency output signal, 26 ... Intermediate frequency signal selection circuit,
27 ... Intermediate frequency signal selection control circuit, 30 ... Second intermediate frequency amplification stage, 31 ... Adaptive tracking filter circuit, 34
... reception station signal level detection circuit, 36 ... adjacent station signal level detection circuit, 40 ... intermediate frequency signal demodulation circuit.

Claims (1)

(57) [Claims] 1. A double superheterodyne FM radio receiver comprising a first intermediate frequency amplification stage and a second intermediate frequency amplification stage having a signal pass band narrower than the signal pass band of the first intermediate frequency amplification stage. An inverse conversion circuit for inversely converting the output signal of the second intermediate frequency amplification stage into a signal of the first intermediate frequency, a narrow band intermediate frequency signal inversely converted by the inverse conversion circuit, and the first intermediate frequency amplification An intermediate frequency signal selecting circuit for selecting one of the two intermediate frequency signals of the wide band intermediate frequency signal which is the output of the stage and supplying it to the intermediate frequency signal demodulating circuit; and a second intermediate frequency amplifying stage of the second intermediate frequency amplifying stage.
A receiving station signal level detection circuit for detecting the signal level of the receiving station based on the signal component of the intermediate frequency signal, and a signal of an adjacent station based on the high frequency signal component of the second intermediate frequency signal of the second intermediate frequency amplification stage An adjacent station signal level detection circuit for detecting the level, and the wide band in a receiving state in which the signal level of the receiving station is higher than a preset receiving signal level and the signal level of the adjacent station is lower than a preset disturbing signal level An FM radio receiver comprising an intermediate frequency signal selection control means for controlling the intermediate frequency signal selection circuit so as to select the narrow band intermediate frequency signal in the reception state other than the intermediate frequency signal.