JP2002094399A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver in which the bandwidth of an IF filter is stable and generation of noise in an intermediate frequency signal is prevented. SOLUTION: An FM receiver 100 is provided with a receiving antenna 101, a tuning circuit 102, an IF filter circuit 104 that has an IF filter for passing intermediate frequency signals with a frequency bandwidth, whose center is the center frequency among intermediate frequency signals generated by a mixer circuit 103, an adjacent disturbance detection circuit 109 that detects the signal level of the intermediate frequency signal, corresponding to a radio wave transmitted from broadcast stations other than a desired broadcast station among intermediate frequency signals which pass through the IF filter, and a microcontroller 108 that revises the frequency bandwidth of the IF filter, in response to the signal level detected by the adjacent disturbance detection circuit 109.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus for preventing interference caused by radio waves transmitted by another broadcast station when receiving a radio wave transmitted by a specific broadcast station.
The present invention relates to a receiver that prevents interference by radio waves transmitted by other broadcast stations by changing the frequency bandwidth of a signal passed by a band filter that passes an intermediate frequency signal.

[0002]

2. Description of the Related Art Conventionally, when receiving a radio wave transmitted by a specific broadcast station, another broadcast station transmits the signal by changing the frequency bandwidth of a signal passed by a band filter that passes an intermediate frequency signal. An FM receiver as shown in FIG. 6 is known as a receiving device for preventing interference by radio waves.

A conventional FM will be described below with reference to FIGS.
The operation of the receiver 200 will be described.

[0004] The FM receiver 200 includes a receiving antenna 201.
Receiving a radio wave, and from the received radio wave, a tuning circuit 2
02, a radio wave transmitted by a broadcast station desired to be received (hereinafter referred to as a desired broadcast station) is stably selected and amplified. The radio wave stably selected and amplified by the tuning circuit 202 is mixed by the mixer circuit 203 with a signal having a frequency higher than the frequency of the radio wave transmitted by the desired broadcasting station by 10.7 MHz so that the frequency of the radio wave is 10.7 MHz. The frequency is converted to an intermediate frequency and converted to an intermediate frequency signal. Here, the frequency of the radio wave transmitted by the desired broadcasting station is 1
The signal having a frequency higher than 0.7 MHz is oscillated by a local oscillation circuit (not shown) in the PLL circuit 207. Further, the PLL circuit 207 includes a microcontroller 208.
Is controlled by

[0005] The intermediate frequency signal converted by the mixer circuit 203 is reduced by an IF (Intermediate Frequency) filter circuit 204 from radio interference (hereinafter referred to as adjacent interference) due to radio waves transmitted by broadcast stations other than the desired broadcast station. And after being amplified, the limiter amplifier 20
5, the amplitude is limited, and only the frequency component is set. When the intermediate frequency signal is converted into only a frequency component by the limiter amplifier 205, the detection circuit 206 generates an audio signal from the intermediate frequency signal, and transmits the generated audio signal to a demodulation circuit and audio (not shown).

[0006] The intermediate frequency signal of which only the frequency component is determined by the limiter amplifier 205 is detected by the adjacent interference detection circuit 209 to determine the strength of the adjacent interference received.
The strength of the detected adjacent interference is determined by an adjacent interference detection circuit 209.
Is output to the microcontroller 208. Microcontroller 208 that outputs the strength of adjacent interference
Is determined according to the strength of the adjacent interference, whether or not the intermediate frequency signal of which only the frequency component is determined by the limiter amplifier 205 is subjected to the adjacent interference, and if the intermediate frequency signal is determined to be the adjacent interference. Immediately, the IF filter circuit 204 narrows the bandwidth of the IF filter to reduce adjacent interference.

More specifically, as shown in FIG. 7, when receiving the FM broadcast, the microcontroller 208 causes the adjacent interference detection circuit 209 to detect the level of the adjacent interference for a predetermined time (step S251). It is determined whether there has been adjacent interference during a predetermined time (step S2).
52).

If it is determined that there is adjacent interference during a certain period of time, the microcontroller 208 causes the IF filter circuit 204 to reduce the bandwidth of the IF filter to reduce the adjacent interference (step S255), and again maintains the constant interference. During the time, the adjacent interference detection circuit 209 detects the level of the adjacent interference (step S251). If it is determined that there is no adjacent interference for a certain period of time, the microcontroller 2
08 judges whether or not the bandwidth of the IF filter of the IF filter circuit 204 is the widest (step S253).

When the microcontroller 208 determines that the bandwidth of the IF filter of the IF filter circuit 204 is the widest state, the microcontroller 208 again causes the adjacent interference detection circuit 209 to detect the intensity of the adjacent interference for a predetermined time ( Step S251). If the microcontroller 208 determines that the bandwidth of the IF filter of the IF filter circuit 204 is not the widest state, the microcontroller 208 causes the IF filter circuit 204 to increase the bandwidth of the IF filter by one step (step S254), and again. , The adjacent interference detection circuit 209 detects the level of the adjacent interference for a predetermined time (step S
251).

[0010] As described above, the FM receiver 200
When receiving a radio wave transmitted by a specific broadcast station, that is, a desired broadcast station, interference by radio waves transmitted by another broadcast station, that is, a broadcast station other than the desired broadcast station, is prevented.

[0011]

However, in the above-mentioned conventional receiver, if the determination of the strength of the adjacent interference is frequently reversed or fluctuated in a short time due to a large fluctuation of the electric field strength, the IF filter is not used. However, since the bandwidth of the IF filter is not stable, there is a problem that a sense of incongruity is generated in the auditory sense, or noise is generated in the intermediate frequency signal due to adjacent interference immediately after increasing the bandwidth of the IF filter.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a receiver in which the IF filter has a stable bandwidth and prevents noise from occurring in the intermediate frequency signal.

[0013]

SUMMARY OF THE INVENTION A receiving apparatus of the present invention converts a signal into a radio wave having a different frequency and transmits the radio wave when the radio wave transmitted by one of the broadcast stations is received. In a receiving apparatus that prevents interference by the radio waves transmitted by other broadcasting stations among the plurality of broadcasting stations,
By receiving the radio waves, of the received radio waves, by converting the frequency of the radio waves transmitted by the one broadcast station to an intermediate frequency, frequency conversion means for generating an intermediate frequency signal from the received radio waves, Among the intermediate frequency signals generated by the frequency conversion means, a bandpass filter that passes the intermediate frequency signal having a frequency bandwidth centered on the intermediate frequency, and the intermediate frequency signal that passes through the bandpass filter, A signal level detection unit that detects a signal level of the intermediate frequency signal corresponding to the radio wave transmitted by another broadcast station; and the frequency band of the bandpass filter according to the signal level detected by the signal level detection unit. Bandwidth changing means for changing the width. With this configuration, the receiving apparatus of the present invention can change the bandwidth of the IF filter according to the signal level detected by the signal level detecting means as well as the presence / absence of adjacent interference. It is possible to avoid a sense of incongruity or noise due to frequent changes in the bandwidth of the IF filter in an unstable state in which adjacent interference is not received.

Further, in the receiving apparatus according to the present invention, the bandwidth changing means may divide the signal level into a plurality of areas according to the value of the signal level, and the bandwidth may be adjusted according to the divided area. The frequency band to be associated with any one of the frequency bandwidths to be changed by the changing unit, and the frequency band to which the signal level detected by the signal level detecting unit is made to correspond is the frequency band of the band filter. If the width is smaller than the width, the frequency bandwidth of the bandpass filter is changed to the frequency bandwidth corresponding to the signal level detected by the signal level detection means, the frequency band detected by the signal level detection means If the frequency bandwidth to which the signal level is associated is not narrower than the frequency bandwidth of the bandpass filter for a predetermined time, The frequency bandwidth of the bandpass filter, is characterized in changing one step wide frequency bandwidth. With this configuration, the receiving device of the present invention
When there is adjacent interference, the IF filter bandwidth can be reduced stably by narrowing the IF filter bandwidth, and the IF filter bandwidth can be gradually returned when the adjacent interference is weakened and a stable reception state is obtained. A good reception state can be stably maintained.

Further, in the receiving apparatus according to the present invention, the bandwidth changing unit may divide the signal level into a plurality of regions according to the value of the signal level, and the bandwidth may be determined according to the divided region. The frequency band to be associated with any one of the frequency bandwidths to be changed by the changing unit, and the frequency band to which the signal level detected by the signal level detecting unit is made to correspond is the frequency band of the band filter. If the width is smaller than the width, the frequency bandwidth of the bandpass filter is changed to the frequency bandwidth corresponding to the signal level detected by the signal level detection means, the frequency band detected by the signal level detection means If the frequency bandwidth to which the signal level is associated is wider than the frequency bandwidth of the bandpass filter for a predetermined time, The frequency bandwidth of the filter, is characterized in changing one step wide frequency bandwidth. With this configuration, the receiving apparatus of the present invention stably narrows the IF filter bandwidth when adjacent interference is present to reduce the adjacent interference, and gradually reduces the adjacent interference when a stable reception state is obtained. Since the IF filter bandwidth can be returned, a good reception state can be stably maintained.

[0016]

[First Embodiment]

A receiving apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

First, the configuration of the receiving apparatus according to the present embodiment will be described with reference to FIG.

In FIG. 1, among a plurality of broadcasting stations which convert signals into radio waves having different frequencies and transmit the same, when receiving a radio wave transmitted by one broadcasting station, ie, a desired broadcasting station, a plurality of broadcast stations are received. FM that prevents interference by radio waves transmitted by other broadcast stations, that is, broadcast stations other than the desired broadcast station
The receiver 100 includes a receiving antenna 101 for receiving a broadcast wave transmitted from a broadcast station, a tuning circuit 102 for stably selecting and amplifying a radio wave of a desired broadcast station, and a tuning circuit 102.
And a mixer circuit 103 that converts the frequency of the radio wave amplified by the tuning into an intermediate frequency to generate an intermediate frequency signal from the radio wave amplified by the tuning circuit 102.

Here, the receiving antenna 101, the tuning circuit 1
02, and the mixer circuit 103 receives the radio wave, and converts the frequency of the radio wave transmitted by the desired broadcasting station out of the received radio wave into an intermediate frequency, thereby generating an intermediate frequency signal from the received radio wave. Means.

Further, the FM receiver 100 operates as a band filter that passes an intermediate frequency signal having a frequency bandwidth centered on the intermediate frequency, that is, an IF filter bandwidth, among the intermediate frequency signals generated by the frequency conversion means. An IF filter circuit 104 having an IF filter, a limiter amplifier 105 that limits the amplitude of an intermediate frequency signal passing through the IF filter and uses the intermediate frequency signal as a frequency component only, and an audio signal generated from the intermediate frequency signal. A demodulation circuit (not shown) and a detection circuit 106 for transmitting the audio signal to audio.

The FM receiver 100 has a local oscillation circuit (not shown) therein, and oscillates a signal having a frequency higher than the frequency of a radio wave transmitted by a desired broadcasting station by 10.7 MHz by the local oscillation circuit. A PLL circuit 107 for outputting to the mixer circuit 103, a microcontroller 108 for controlling the PLL circuit 107, and an intermediate frequency signal corresponding to a radio wave transmitted by a broadcasting station other than the desired broadcasting station among the intermediate frequency signals passing through the IF filter Adjacent interference detection circuit 109 as signal level detection means for detecting the signal level of
And Here, the microcontroller 10
Reference numeral 8 denotes a bandwidth changing unit that changes the IF filter bandwidth in five stages according to the signal level detected by the adjacent interference detection circuit 109.

The microcontroller 108 divides the signal level into a plurality of areas according to the value of the signal level, and selects one of five IF filter bandwidths according to the divided area. When the IF filter bandwidth corresponding to the signal level detected by the adjacent interference detection circuit 109 is smaller than the actual IF filter bandwidth, the actual IF filter bandwidth is set to: The signal level detected by the adjacent interference detection circuit 109 is changed to the corresponding IF filter bandwidth.

Further, the microcontroller 108 determines that the IF filter bandwidth to which the signal level detected by the adjacent interference detection circuit 109 corresponds is not narrower than the actual IF filter bandwidth for shorter than a predetermined time.
The actual IF filter bandwidth is prevented from being changed, and the IF filter bandwidth to which the signal level detected by the adjacent interference detection circuit 109 is made to correspond to for a predetermined period of time. If the width is not smaller than the width, the actual IF filter bandwidth is changed to one step wider IF filter bandwidth.

Next, the operation of the receiving apparatus according to the present embodiment will be described with reference to FIGS.

As shown in FIG. 2, when receiving the FM broadcast, the microcontroller 108 causes the adjacent interference detection circuit 109 to detect the level of the adjacent interference for a fixed time (step S111), and It is determined whether or not adjacent interference has been received (step S112). Here, the microcontroller 108 detects the average value of the signal levels of the intermediate frequency signals corresponding to the radio waves transmitted by the broadcast stations other than the desired broadcast station detected by the adjacent interference detection circuit 109 during a predetermined time (hereinafter, the adjacent detection is performed). It is determined whether or not adjacent interference has been detected based on the voltage. Further, as shown in FIG. 3, the microcontroller 108 determines that the adjacent detection voltage is V1,
In other words, when it is in the range of Va or more and less than Vb, it is determined that adjacent interference has not been received, and the adjacent detection voltages are V2, V3, V
If it is within the range of any one of V4 and V5, it is determined that adjacent interference has occurred.

If it is determined in step S112 that adjacent interference has been received for a certain period of time, the microcontroller 108 determines the actual IF filter bandwidth, that is, the current I filter bandwidth.
The adjacent detection voltage (hereinafter, referred to as the previous detection value) V ′ corresponding to the F filter bandwidth is compared with the adjacent detection voltage (hereinafter, referred to as the present detection value) V detected in the immediately preceding step S111 (step). S113), it is determined whether or not the current detection value V is equal to or less than the previous detection value V '(step S114).

If it is determined in step S114 that the current detection value V is not smaller than the previous detection value V ', that is, if the current detection value V is larger than the previous detection value V', the microcontroller 108 sets the IF filter bandwidth to the current detection value V '. Detection value V
(Step S115), and the counter variable n
Is set to 1 (step S120), and the adjacent interference detection circuit 109 detects the strength of the adjacent interference again for a predetermined time (step S111).

If it is determined in step S112 that no adjacent interference has been received for a predetermined time, or if it is determined in step S114 that the current detection value V is equal to or less than the previous detection value V ', the microcontroller 108
Determines whether the IF filter bandwidth is the largest (step S116). IF in step S116
If the microcontroller 108 determines that the filter bandwidth is the maximum, the microcontroller 108 sets the value of the counter variable n to 1 (step S120), and again causes the adjacent interference detection circuit 109 to detect the level of the adjacent interference for a certain period of time (step S120). Step S111). If it is determined in step S116 that the IF filter bandwidth is not the largest, the microcontroller 108 determines whether the value of the counter variable n is a predetermined integer N (step S117).

In step S117, the counter variable n
Is not a predetermined integer N, 1 is added to the value of the counter variable n (step S118), and the adjacent interference detection circuit 109 detects the strength of the adjacent interference again for a fixed time (step S111). ).

In step S117, the counter variable n
Is determined to be a predetermined integer N, the IF filter bandwidth is widened by one step (step S119), and the microcontroller 108 sets the value of the counter variable n to 1 (step S120), and then keeps it constant again. During the time, the adjacent interference detection circuit 109 detects the level of the adjacent interference (step S111).

As described above, the FM receiver 100
When receiving a radio wave transmitted by a specific broadcast station, ie, a desired broadcast station, interference by radio waves transmitted by another broadcast station, ie, a broadcast station other than the desired broadcast station, is prevented.

In this embodiment, there are five states in which the IF filter bandwidth can be obtained.
According to the present invention, the IF filter bandwidth can be obtained in any number of stages as long as the number of stages is three or more.
Further, the IF filter bandwidth may be set in two stages of wide and narrow. [Second embodiment]

A receiving apparatus according to a second embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 4, the configuration of the receiving apparatus according to the present embodiment, except for the microcontroller 131,
The configuration is almost the same as the configuration of the receiving device according to the first embodiment shown in FIG.

In the FM receiver 130, the microcontroller 131 divides the signal level into a plurality of regions according to the value of the signal level, and selects one of five IF filter bandwidths according to the divided region. If the IF filter bandwidth to which the signal level detected by the adjacent interference detection circuit 109 is made to correspond is narrower than the actual IF filter bandwidth, The bandwidth is changed to an IF filter bandwidth to which the signal level detected by the adjacent interference detection circuit 109 is made to correspond.

Further, in the FM receiver 130, the microcontroller 131 determines that the IF filter bandwidth corresponding to the signal level detected by the adjacent interference detection circuit 109 is equal to the actual IF filter bandwidth.
And changing the actual IF filter bandwidth if the IF filter bandwidth corresponding to the signal level detected by the adjacent interference detection circuit 109 is wider than the actual IF filter bandwidth for a period shorter than a predetermined time. If the IF filter bandwidth corresponding to the signal level detected by the adjacent interference detection circuit 109 is wider than the actual IF filter bandwidth for a predetermined time, the actual IF filter The bandwidth is changed to one step wider IF filter bandwidth.

Hereinafter, the operation of the receiving apparatus according to the present embodiment will be described with reference to FIGS.

As shown in FIG. 5, when receiving the FM broadcast, the microcontroller 131 causes the adjacent interference detection circuit 109 to detect the level of the adjacent interference for a predetermined time (step S151), and It is determined whether or not adjacent interference has been received (step S152).

If it is determined in step S152 that adjacent interference has been received for a predetermined period of time, the microcontroller 131 compares the previous detection value V 'with the current detection value V (step S153). Previous detection value V
It is determined whether it is less than '(step S154).

If it is determined in step S154 that the current detection value V is not less than the previous detection value V ', the microcontroller 131 determines whether the current detection value V is equal to the previous detection value V' (step S155). . If the microcontroller 131 determines that the current detection value V is equal to the previous detection value V 'in step S155, the microcontroller 131 sets the value of the counter variable n to 1 (step S161). The level of interference is detected (step S151). Step S15
5, when the microcontroller 131 determines that the current detection value V is not equal to the previous detection value V ′, that is, the current detection value V is larger than the previous detection value V ′, the microcontroller 131 changes the IF filter bandwidth according to the current detection value V. And narrow (Step S
156), and sets the value of the counter variable n to 1 (step S1).
61) The adjacent interference detection circuit 109 detects the level of the adjacent interference again for a predetermined time (step S151).

If it is determined in step S152 that no adjacent interference has been received for a predetermined time, or if it is determined in step S154 that the current detection value V is less than the previous detection value V ', the microcontroller 131
Determines whether the IF filter bandwidth is maximum (step S157). IF in step S157
If it is determined that the filter bandwidth is the maximum, the microcontroller 131 sets the value of the counter variable n to 1 (step S161), and again causes the adjacent interference detection circuit 109 to detect the intensity of the adjacent interference for a fixed time (step S161). Step S151). If it is determined in step S157 that the IF filter bandwidth is not the maximum, the microcontroller 131 determines whether the value of the counter variable n is a predetermined integer N (step S158).

In step S158, the counter variable n
Is not a predetermined integer N, 1 is added to the value of the counter variable n (step S159), and the adjacent interference detection circuit 109 again detects the intensity of the adjacent interference for a certain period of time (step S151). ).

In step S158, the counter variable n
Is determined to be a predetermined integer N, the IF filter bandwidth is widened by one step (step S160), and the microcontroller 131 sets the value of the counter variable n to 1 (step S161) and then keeps it constant. During the time, the adjacent interference detection circuit 109 detects the level of the adjacent interference (step S151).

As described above, the FM receiver 130
When receiving a radio wave transmitted by a specific broadcast station, ie, a desired broadcast station, interference by radio waves transmitted by another broadcast station, ie, a broadcast station other than the desired broadcast station, is prevented.

In this embodiment, there are five states in which the IF filter bandwidth can be obtained.
According to the present invention, the IF filter bandwidth can be obtained in any number of stages as long as the number of stages is three or more.
Further, the IF filter bandwidth may be set in two stages of wide and narrow.

[0047]

As described above, according to the present invention,
The receiving apparatus of the present invention can change not only the presence / absence of adjacent interference but also the signal level detected by the signal level detecting means, so that the electric field greatly fluctuates and receives or does not receive the adjacent interference. It is possible to avoid discomfort and noise generation due to frequent changes in the IF filter bandwidth in an unstable state.

[Brief description of the drawings]

FIG. 1 is a block diagram of a receiving device according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the receiving apparatus shown in FIG. 1;

FIG. 3 is a diagram illustrating a correspondence between an adjacent detection voltage and an IF filter bandwidth of the receiving apparatus illustrated in FIG. 1;

FIG. 4 is a block diagram of a receiving device according to a second embodiment of the present invention.

FIG. 5 is a flowchart for explaining the operation of the receiving apparatus shown in FIG. 4;

FIG. 6 is a block diagram of a conventional receiver.

FIG. 7 is a flowchart for explaining the operation of the receiving apparatus shown in FIG. 6;

[Explanation of symbols]

100, 130 FM receiver (receiving device) 101 Receiving antenna (frequency converting means) 102 Tuning circuit (frequency converting means) 103 Mixer circuit (frequency converting means) 104 Filter circuit (band filter) 108, 131 Microcontroller (bandwidth change Means) 109 Adjacent interference detection circuit (signal level detection means)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisao Tanaka 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Inside Matsushita Communication Industrial Co., Ltd. No.3-1 Matsushita Communication Industrial Co., Ltd. (72) Inventor Kimito Terai 4-3-1 Tsunashimahigashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture F-term inside Matsushita Communication Industrial Co., Ltd. 5K020 CC03 DD01 EE04 HH13 5K052 AA01 BB04 CC04 DD04 EE04 EE13 EE22 FF07 GG33

Claims (3)

[Claims] When receiving a radio wave transmitted by one of a plurality of broadcasting stations which converts a signal into radio waves having different frequencies and transmits the same, the other broadcasting stations of the plurality of broadcasting stations receive the radio waves transmitted by the one broadcasting station. In a receiving apparatus for preventing interference by the radio wave transmitted by a station, receiving the radio wave, of the received radio wave, by converting the frequency of the radio wave transmitted by the one broadcast station to an intermediate frequency, receiving Frequency converting means for generating an intermediate frequency signal from the radio wave, and, among the intermediate frequency signals generated by the frequency converting means, a bandpass filter for passing the intermediate frequency signal having a frequency bandwidth centered on the intermediate frequency. , Among the intermediate frequency signals passing through the bandpass filter,
Signal level detecting means for detecting a signal level of the intermediate frequency signal corresponding to the radio wave transmitted by the other broadcast station; and the frequency of the bandpass filter according to the signal level detected by the signal level detecting means. A receiving apparatus comprising: a bandwidth changing unit configured to change a bandwidth. 2. The frequency changing unit, wherein the bandwidth changing unit divides the signal level into a plurality of regions according to the value of the signal level, and changes the signal level by the bandwidth changing unit according to the divided region. Correspond to any one of the frequency bandwidths of the bandwidth, and if the frequency bandwidth to which the signal level detected by the signal level detection means is associated is narrower than the frequency bandwidth of the band filter, Changing the frequency bandwidth of the bandpass filter to the frequency bandwidth to which the signal level detected by the signal level detection means is associated, and wherein the signal level detected by the signal level detection means is associated. If the frequency bandwidth is not less than the frequency bandwidth of the band filter for a predetermined time, the frequency of the band filter The receiving apparatus according to claim 1, wherein the several bandwidths are changed to a frequency bandwidth one step wider. 3. The frequency changing unit, wherein the bandwidth changing unit divides the signal level into a plurality of regions according to the value of the signal level, and changes the frequency by the bandwidth changing unit according to the divided region. Correspond to any one of the frequency bandwidths of the bandwidth, and if the frequency bandwidth to which the signal level detected by the signal level detection means is associated is narrower than the frequency bandwidth of the band filter, Changing the frequency bandwidth of the bandpass filter to the frequency bandwidth to which the signal level detected by the signal level detection means is associated, and wherein the signal level detected by the signal level detection means is associated. If the frequency bandwidth is wider than the frequency bandwidth of the band filter for a predetermined time, the frequency band of the band filter The receiving device according to claim 1, wherein the bandwidth is changed to a frequency bandwidth that is wider by one step.