JPH0518134U - AM receiver - Google Patents

Abstract

(57) [Abstract] [Purpose] When there is no beat interference, the band of the intermediate frequency amplifier is widened to reproduce the sound quality as close as possible to the sound quality of the transmitting side, and when there is beat interference, the band is narrowed to achieve beat interference. It is an object of the present invention to provide an AM receiver adapted to automatically switch bands by applying a clock so as to reduce the above. [Structure] Wide band and narrow band 2 in the intermediate frequency amplifier circuit
One filter, a switch for switching these two filters, a clock that outputs a signal at a preset time, and a microcomputer that controls the output of the band switching signal by the signal output from the clock.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an AM receiver, and in particular, is an AM receiver suitable for automatically switching the intermediate frequency band to a narrow band during a time period when beat interference occurs so as not to lower the clarity of the target station.

[0002]

[Prior art]

 Conventional AM receivers are configured to reduce the beat interference by narrowing the intermediate frequency band in consideration of the case where the beat interference occurs.

[0003]

[Problems to be solved by the device]

 However, in the conventional AM receiver described above, the band of the intermediate frequency band is narrowed in order to reduce the beat interference by the adjacent station. Therefore, the broadcasting station transmits with a flat frequency characteristic up to the high frequency range. However, there was a drawback that the high frequency range was attenuated and played back on the receiver side.

The present invention has been made in view of the above points, and an object of the invention is to eliminate the drawbacks of the related art, and to configure the intermediate frequency band so that it can be switched between a wide band and a narrow band. It provides an AM receiver that automatically narrows the band at a specific time when interference occurs.

[0005]

[Means for Solving the Problems]

 The AM receiver according to the present invention has a display means capable of displaying time, and is configured to narrow the band of the intermediate frequency stage to reduce beat interference. 2 and the band switching means for switching the band of the filter at a preset time.

[0006]

[Action]

 According to the present invention, in an AM receiver having display means capable of displaying time and configured to narrow the band of the intermediate frequency stage to reduce the beat interference, a narrow band and a wide band are provided in the intermediate frequency stage. Since two filters and band switching means for switching the band of this filter at a preset time are provided, the band of the intermediate frequency band is narrowed at the time of beat interference and the beat In the time zone where there is no interference, the band of the intermediate frequency band is made sufficiently wide, and the sound quality can be automatically reproduced with a sound quality close to that of the transmitting side.

[0007]

【Example】

 An embodiment of an AM receiver according to the present invention will be described with reference to FIG.

FIG. 1 is a configuration block diagram showing an embodiment of the present invention.

In the figure, 1 is an RF amplifier, 2 is a mixer, 3 is a local oscillator circuit, 4 is a wide band filter, 5 is a narrow band filter, 6 is a detection circuit, 7 is a microcomputer, 8 is a display unit, and 9 is a display unit. Band changeover switches (A) and 10 are band changeover switches (B).

As a block configuration, the output of the RF amplifier 1 is input to the mixer 2, and the output of the local oscillation circuit 3 is also input to the mixer 2. The output of the mixer 2 is connected to the common terminal of the band changeover switch 9. There is.

Further, one contact terminal of the band change switch (A) 9 is connected to the wide band filter 4, and the other one contact terminal is connected to the narrow band filter 5, and the wide band filter 4 and the narrow band filter 5 are connected. The output side of each is connected to the contact terminals of the band switching filter (B) 10, and the common terminal is connected to the detection circuit 6.

Further, the control terminals of the band changeover switches (A) 9 and (B) 10 are connected to the output port of the microcomputer 7 and the input port thereof is connected to the display section 8 having a clock function. There is.

In the figure, the intermediate frequency amplifier circuit is omitted for simplification of description.

As the switching operation of the filter configured as described above, when the clock provided on the display unit 8 reaches a preset time, a signal is sent to the microcomputer 7 and the microcomputer which receives this signal. 7 outputs a band switching signal.

When the band switching signal is output from the microcomputer 7, the band switching switches (A) 9 and (B) 10 switch from the wide band filter 4 side to the narrow band filter 5 side to narrow the band of the intermediate frequency amplifier. Therefore, the beat interference of the adjacent station will be suppressed.

When the clock of the display unit 8 has passed a certain time, the microcomputer 7 outputs a band switching signal again to switch the band switching switches (A) 9 and (B) 10 to the wide band filter 4 side. The band of the frequency amplifier is wide.

As described above, at the time when the beat interference increases (at night in the case of AM), the band of the intermediate frequency amplifier is narrowed, and the other time bands are widebanded. , Can automatically have the best reception characteristics.

In this embodiment, the wide band filter and the narrow band filter are switched in parallel, but as another application example, the wide band filter and the narrow band filter are connected in series to obtain a narrow band when receiving in a wide band. The filter may be switched to pass.

[0019]

[Effect of the device]

 Since the AM receiver according to the present invention is configured as described above, it has the following effects.

By making the intermediate frequency band wide in the time zone without beat interference and narrowing the band in the time zone in which beat interference occurs, high sound quality can be obtained in the time zone without beat interference. The effect is that the receiver can always be in the best condition at that time so that the disturbing wave can be removed during the period of beat disturbance so as not to cause discomfort.

Moreover, it has excellent features such as a simple circuit configuration and easy implementation.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention.

[Explanation of symbols] 1 RF amplifier 2 Mixer 3 Local oscillation circuit 4 Wide band filter 5 Narrow band filter 6 Detection circuit 7 Microcomputer 8 Display section 9 Band change switch (A) 10 Band change switch (B)

Claims (1)

[Scope of utility model registration request] 1. An AM receiver having display means capable of displaying time and configured to narrow the band of an intermediate frequency stage to reduce beat interference, wherein the intermediate frequency stage has a narrow band and a wide band. An AM receiver comprising two filters and band switching means for switching the band of the filter at a preset time.