JP3072667B2 - Superheterodyne 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 superheterodyne receiver.

[0002]

2. Description of the Related Art Broadcasting in the medium wave band uses 531 kHz to 1602 kHz as a frequency band and uses 9 kHz frequency positions among them. The broadcast wave signal is a DSB signal.

On the other hand, in the shortwave band, commercial broadcasting called a meter band uses a DSB signal, and in a communication band outside the broadcasting band, a USB signal is mainly used. Further, in amateur radio below 10 MHz, an LSB signal is used.

[0004]

As described above, in medium-wave broadcasting, short-wave broadcasting or short-wave communication, the transmission signal is a DSB signal, a USB signal,
It may be an LSB signal. The DSB signal has a wide occupied bandwidth, and the SSB signal has a narrow occupied bandwidth.

Therefore, when receiving such medium-wave broadcast, short-wave broadcast or short-wave communication, it is necessary to switch the reception mode to the DSB reception mode, USB reception mode, or LSB reception mode in accordance with the transmission signal. Furthermore, at this time, the bandwidth of the intermediate frequency amplifier is also
It is necessary to switch according to the bandwidth of the transmission signal.

[0006] However, it is troublesome to switch the reception mode and the bandwidth in this way. In particular, when performing a scan reception in a synthesizer receiver, it is necessary to temporarily stop the scan and switch the reception mode and the bandwidth, and the merit of the scan reception is reduced.

The present invention is to solve such a problem.

[0008]

As described above, in commercial broadcasting called medium-wave broadcasting or meter band, DS is used.
The B signal is used and its occupied bandwidth is wide. On the other hand, in other short-wave communication, a USB signal is used and its occupied bandwidth is narrow.

In shortwave communication, amateur radio is LS
Although the B signal is used, the frequency band allowed for the amateur radio is known.

The present invention pays attention to these points, and automatically switches the reception mode and the bandwidth according to the reception frequency or the reception band.

That is, according to the present invention, when the reference numerals of the respective parts correspond to the embodiments described later, the DSB signal, the USB signal, and the LSB signal are received by the superheterodyne receiver as the received signal. A first intermediate frequency circuit 16W having a pass bandwidth corresponding to the occupied bandwidth of the second intermediate frequency circuit 16N having a pass bandwidth corresponding to the occupied bandwidth of the USB signal and the LSB signal; A first switch circuit 47 for selectively and effectively switching between the intermediate frequency circuit 16W and the second intermediate frequency circuit 16N; a second frequency BFO signal corresponding to the first frequency corresponding to the USB signal; , A second switch circuit 49 for selectively and effectively extracting a BFO signal having a frequency of And a data table DTBL, which is a set of reception mode data indicating which of the B signal and the LSB signal corresponds to the reception signal. , The reception mode data paired with the reception frequency band including the set reception frequency is extracted, and when the extracted reception mode data indicates the DSB signal, the first switch circuit 47 is turned off. Switching control is performed to select the first intermediate frequency circuit 16W, and an intermediate frequency signal obtained by selecting the first intermediate frequency circuit 16W is subjected to AM detection to extract an audio signal. Is a USB signal or LSB
When the signal is shown, the first switch circuit 47 is switched and controlled to select the second intermediate frequency circuit 16N, and the second switch circuit 49 is switched and controlled in accordance with the extracted reception mode data. Of the BFO signals of the first and second frequencies, a BFO signal corresponding to the USB signal or the LSB signal indicated by the extracted reception mode data is extracted, and the extracted BFO signal and the second intermediate frequency circuit 16N are selected. Is supplied to the mixer circuit 43 to extract an audio signal, and when a first predetermined key operation is performed,
First switch circuit 47 and second switch circuit 49
Irrespective of the switching result, the switching of the first and second switch circuits 47 and 49 is controlled to sequentially change the reception mode to the reception mode of the DSB signal, the USB signal or the LSB signal, and the second predetermined When key operation,
First intermediate frequency circuit 16W and second intermediate frequency circuit 1
6N, regardless of the result of the selection,
7, the first intermediate frequency circuit 16W or the second intermediate frequency circuit 16N is alternately selected.

[0012]

When the tuning is performed, the data table DTBL is referred to and the receiving mode and the bandwidth are automatically set to the state corresponding to the receiving frequency f11.

[0013]

FIG. 1 shows an example of the present invention, in which the present invention is applied to a double superheterodyne receiver. In addition, the receiver performs channel selection by changing both the first local oscillation frequency and the second local oscillation frequency.

Further, in this example, the reception frequency f11: 150 kHz to 30 MHz (approximate value) The first intermediate frequency f13: 55.845 MHz The second intermediate frequency f15: 455 kHz, and the first local oscillation The frequency is changed in steps of 1 kHz, and the second local oscillation frequency is changed in steps of 100 Hz.
This can be changed in steps.

That is, the reception signal S11 is
Is supplied to the first mixer circuit 13 through the high frequency amplifier 12, and the first local oscillation signal S 21 is supplied to the mixer circuit 13 from the first local oscillation circuit 21. In this case, the frequency f21 of the local oscillation signal S21 is equal to the reception frequency f11.
Where f21 = f11 + f13 ‥‥‥ (1), and f21 = (150 kHz + 55.845 MHz) 30 (30 MHz + 55.845 MHz) 2 (2) where the frequency f21 changes in steps of 1 kHz. Things.

Thus, the reception signal S11 is transmitted to the mixer circuit 1
At 3, the frequency is converted to a first intermediate frequency signal S13 (intermediate frequency f13) by the first local oscillation signal S21.

The signal S13 is supplied to the second mixer circuit 15 through the first intermediate frequency amplifier 14, and the second local oscillation circuit 31 outputs the second local oscillation signal S31.
Is supplied to the mixer circuit 15. In this case, the frequency f31 of the local oscillation signal S31 is f31 = f13−f15 = f21−f11−f15ｆ (3) with respect to the reception frequency f11, and f31 = (55.39 MHz + 0.5 kHz) )-(55.39 MHz-0.4 kHz) ‥‥‥ (4) However, the frequency f31 changes in steps of 100 Hz.

Thus, the first intermediate frequency signal S13 is converted into the second signal by the second local oscillation signal S31 in the mixer circuit 15.
The frequency is converted to an intermediate frequency signal S15 (intermediate frequency f15).

When a DSB signal is received (during reception of a medium-wave broadcast or a short-wave broadcast, etc.), the signal S15 from the mixer circuit 15 is transmitted over a wide band (pass band is ± 6 kHz, for example).
Is supplied to the AM detection circuit 17 through the second intermediate frequency amplifier 16W and the switch circuit 47, and the audio signal is demodulated.
Is taken out.

When the SSB signal is received (when receiving short-wave communication or the like), the intermediate frequency signal S from the mixer circuit 15 is output.
15 is supplied to the balanced mixer circuit 43 through the second intermediate frequency amplifier 16N having a narrow band (pass band is, for example, ± 2.8 kHz) and the switch circuit 47.

When the SSB signal is a USB signal (for general short-wave communication or the like), a frequency f41, for example, a BFO signal S41 of f41 = 457 kHz is extracted from the BFO 41, and this BFO signal S41 is switched. The signal is supplied to the mixer circuit 43 through the circuit 49.

Thus, the mixer circuit 43 outputs the USB
A demodulated audio signal is extracted from the signal, and the audio signal is extracted to the terminal 18 through the switch circuit 48.

Further, when the SSB signal is an LSB signal (for example, in the case of amateur radio), a frequency f42, for example, a BFO signal S42 of f42 = 453 kHz is extracted from the BFO 42, and the BFO signal S42 is The signal is supplied to the mixer circuit 43 through.

Thus, the mixer circuit 43 outputs the LSB
A demodulated audio signal is extracted from the signal, and the audio signal is extracted to the terminal 18 through the switch circuit 48.

According to the above configuration, the reception frequency f
11 becomes f11 = f21−f31−f15 ‥‥‥‥‥‥ (5) from the equation (3).

Since the frequencies f21 and f31 change the ranges of the equations (2) and (4) according to the reception frequency f11,
From equation (5), for example, f21 = 150 kHz + 55.845 MHz, f
When 31 = 55.39 MHz + 0.5 kHz, f11 = f21−f31−f15 = (150 kHz + 55.845 MHz) − (55.39 MHz + 0.5 kHz) −455 kHz = 150 kHz−0.5 kHz. F21 = 30 MHz + 55.845 MHz, f31 = 55.3
When 9 MHz−0.4 kHz, f11 = f21−f31−f15 = (30 MHz + 55.845 MHz) − (55.39 MHz−0.4 kHz) −455 kHz = 30 MHz + 0.4 kHz. Therefore, the reception band is approximately 150 kHz to 30 M
Hz.

Further, according to the equation (5), when the second local oscillation frequency f31 is constant, the first local oscillation frequency f21 is increased by 1 k.
If the frequency is changed in Hz steps, the reception frequency f11 changes in 1 kHz steps. If the first local oscillation frequency f21 is constant, if the second local oscillation frequency f31 is changed in 100 Hz steps, the reception frequency f11 is changed in 100 Hz steps. To change.

Then, the first local oscillation frequency f31 is set to 1 kHz.
Since the first local oscillation circuit 21 changes the voltage in steps,
And the VCO 21 is PL
It constitutes a part of L20.

That is, as the local oscillation circuit 21, the VCO
21 is provided, the oscillation signal of the VCO 21 is supplied to the first mixer circuit 13 as a first local oscillation signal S21, and the signal S21 is supplied to the variable frequency dividing circuit 22 to be converted into a signal having a frequency of 1 / N. The frequency is divided, and the frequency-divided signal is supplied to the phase comparison circuit 23. Further, an oscillation signal having a reference frequency, for example, a frequency of 1 kHz is taken out from the reference oscillation circuit 24, and this signal is supplied to the phase comparison circuit 23.
The comparison output is applied to the VCO 2 through the low-pass filter 25.
1 as its control voltage.

Therefore, in a steady state, the frequency of the frequency-divided signal from the frequency-dividing circuit 22 and the frequency of the oscillation signal of the oscillation circuit 24 are equal, and the frequency f21 of the oscillation signal S21 at this time is f21 = N × 1 [KHz]. At this time, equation (5) holds.

Therefore, if the frequency division ratio N is changed one by one between 55995 and 85845, the local oscillation frequency f21
However, since the range of equation (2) changes at 1 kHz intervals, the reception frequency f11 can be changed in 1 kHz steps.

Further, the second local oscillation frequency f31 is set to 100 Hz.
Since the second local oscillation circuit 31 changes the voltage in steps,
It is composed of CXO. In this case, the VCXO 31
A variable frequency oscillation circuit using a crystal oscillator and a variable capacitance diode as the oscillation element, and the output voltage V32 of the D / A converter 32 is supplied to the variable capacitance diode as a control voltage. Then, the oscillation signal of the VCXO 31 is used as the second local oscillation signal S31 in the second mixer circuit 1
5 is supplied.

Therefore, when the predetermined control data D32 is supplied to the D / A converter 42, the oscillation frequency f31 of the oscillation signal S31 of the VCXO 31 changes in accordance with the data D32. (Four)
Within the range of the expression, the frequency can be changed in 100 Hz steps, and the reception frequency f11 can be changed in 100 Hz steps.

Therefore, the predetermined frequency division ratio N and data D
If 32 is supplied to the variable frequency dividing circuit 22 and the D / A converter 32, the reception frequency f11 can be changed in steps of 100 Hz in a reception band of 150 kHz to 30 MHz.

Reference numeral 50 denotes a microcomputer for controlling the system, 51 denotes its CPU, and 52 denotes
Is a ROM in which various programs are written, 53 is a RAM for a work area, and 54 is a RAM for holding data.
The memories 52 to 54 are connected to the CPU 51 through the system bus 59.

In this case, the ROM 52 stores, for example, a routine 100 of a flowchart shown in FIG. 2 as a part of the program, and has, for example, a data table DTBL shown in FIG.

That is, this table DTBL is a set of data DFR indicating a frequency band, data DMD indicating a general reception mode in the frequency band, and data DBW indicating a general bandwidth in the frequency band. And the set is provided for each frequency band.

For example, as shown in the column, for the medium wave broadcast band, data DFR indicating the frequency band 531 kHz to 1602 kHz, data DMD indicating that the reception mode is DSB, and the bandwidth Has data DBW indicating that it is a wide band, and as shown in the column, for the next frequency band, the frequency band 1603 kHz to
Data DFR indicating 2249 kHz and the reception mode is USB
And data DBW indicating that the bandwidth is narrow.

The RAM 54 stores preset broadcast station frequency data and last channel (previous
This is a memory for retaining data of the frequency received when the power was turned off) even when the power is turned off.
For this reason, the RAM 54 is a non-volatile memory capable of electrically erasing and writing data, or a memory backed up by a battery.

Further, 61 to 63 are output ports, and these ports 61 to 63 are also connected to the bus 59,
, The dividing ratio N is output and set in the dividing circuit 22.
Data D32 is output from the port 62 and supplied to the D / A converter 32.

Further, the switch circuits 47 to
The control signals are supplied to the switch circuit 47.
Is connected to the intermediate frequency amplifier 16W when the bandwidth is wide, and is connected to the intermediate frequency amplifier 16N when the bandwidth is narrow. Further, the switch circuit 48 is connected to the detection circuit 17 when the reception mode is the DSB reception mode,
In the USB reception mode and the LSB reception mode, it is connected to the mixer circuit 43 side. In addition, the switch circuit 49
When the reception mode is the USB reception mode, it is connected to the BFO 41 side, and when it is in the LSB reception mode, it is connected to the BFO 42 side.

Further, 64 is an LCD controller, 65
Is an LCD, and the display of the LCD 65 is
, The reception frequency, the reception mode, the bandwidth, and the like are displayed.

Reference numeral 66 denotes a key interface circuit through which a function key KFC, a registration key KRG, channel selection keys K01 to K05,
The numeric keypad KTE is connected to the bus 59. Although the functions of these keys KFC to KTE will be described later, each of the keys KFC to KTE is constituted by a non-lock type push switch.

<Tuning by Numeric Keypad> By operating the numeric keypad KTE, a desired receiving frequency f11 can be directly input to select a channel.

That is, a number indicating the frequency f11 to be received is input from the ten key KTE. For example, when it is desired to receive 1242 kHz, "1, 2, 4, 2" of the numeric keypad KTE
Key, and then press the "EXE" key on the numeric keypad KTE.

Then, the processing of the CPU 51 is changed to the routine 1
00, start from step 101, then step 1
In 02, by referring to the data table DTBL, the data DMD of the reception mode and the data DBW of the bandwidth with respect to the frequency input from the numeric keypad KTE are extracted. In this case, since "1242" has been input, data DMD indicating that the reception mode is DSB from the column,
Data DBW indicating that the bandwidth is broadband is extracted.

Subsequently, the processing of the CPU 51 is performed in step 10
3 and in this step 103, step 10
Data DMD and D taken out of data table DTBL in step 2
The switch circuits 47 to 49 are respectively switched according to BW. In this case, the switch circuits 47 to 49 are switched to the states shown in the figure in accordance with the data DMD and DBW in the column.

Next, the processing of the CPU 51 proceeds to step 104. In this step 104, the frequency input from the numeric keypad KTE is converted into a frequency dividing ratio N for selecting the frequency and data D32. 105
In, the frequency dividing ratio N and the data D32 converted in step 104 are supplied to the frequency dividing circuit 22 and the D / A converter 32, and then, in step, the routine 100 ends.

Therefore, in step 105, the reception frequency f11 becomes the frequency of the numerical value inputted from the ten key KTE. Also, at this time, in step 103, the intermediate frequency amplifier 16W or 16N is selected corresponding to the reception frequency f11 to have a bandwidth suitable for the reception frequency f11, and the reception mode is set to the DSB reception mode,
The USB reception mode or the LSB reception mode is set.
In this case, the intermediate frequency amplifier 16W is selected in accordance with the data DMD and DBW in the column to make the bandwidth wide, and the detection circuit 17 is selected to perform general AM detection.

When the reception frequency f11 is designated by the numeric keypad KTE, the frequency f11 is selected, and the reception mode and the bandwidth corresponding to the frequency f11 are set according to the data DFR to DBW of the data table DTBL. .

Although not shown, at this time, the data of the reception frequency f11, the reception mode and the bandwidth are set to LC
The reception frequency f11, the reception mode, and the bandwidth are supplied to the D controller 64, and the LCD 65 displays, for example,
It is displayed as "1242 kHz", "AM" and "WIDE". Alternatively, if the reception frequency f11 is 1603 kHz, "1603 kHz", "USB" and "NARRO"
W ".

The numerical value indicating the reception frequency f11 at this time is written as a last channel data at a predetermined address A00 of the RAM 54.

<< Scan Reception >> The configuration for scan reception is the same as the conventional one, and is not shown in FIG. 1. However, when the scan reception key is pressed, the frequency division ratio N and data D32
Changes by a predetermined magnitude, and this change causes the reception frequency f
11 changes in a predetermined frequency step.

When a broadcast wave signal or the like is received at a certain reception frequency f11, an intermediate frequency signal S15 is obtained. The microcomputer 50 informs the microcomputer 50 that the signal has been received by the detection signal of the signal S15. And the scan stops.

Then, at this time, the routine 100 is executed, and the reception mode and the bandwidth correspond to the reception frequency f11 at that time. The data of the last channel is stored in the RAM 54.

<< Preset of frequency >> Arbitrary frequency f11
When the channel selection key Ki (i = any of 01 to 05) is pressed while the registration key KRG is being selected in a state where is selected, the numerical value indicating the reception frequency f11 at this time is stored in the RAM 54.
The data is written to the address Ai corresponding to the pressed tuning key Ki.

Therefore, the frequency f11 to be preset
, And then pressing the tuning key Ki while pressing the registration key KRG, the received frequency f11 at that time is preset in the pressed tuning key Ki.

Then, the preset frequency f11
Can be selected with one touch by the following “selection by tuning key”.

<< Tuning by Tuning Key >> When the receiving frequency f11 is preset in the tuning key Ki, the tuning key K
When i is pressed, data indicating the frequency f11 written in the address Ai is read from the address Ai corresponding to the pressed key Ki in the RAM 54, and then the routine 100 is executed.

Accordingly, in the same manner as in the case of "selection by ten-key", the frequency f11 registered in the selection key Ki is selected, and according to the result of referring to the data table DTBL, the frequency f11 is selected. The receiving mode and bandwidth are selected accordingly. The data of the last channel is stored in the RAM 54.

Therefore, when the tuning key Ki is pressed, the frequency f11 registered in the key Ki is selected, and the receiving mode and the bandwidth corresponding to the frequency f11 are set, and the frequency f11 is set. Reception is performed.

<< When power is turned on >> When the power is turned on from off, the address A of the last channel of the RAM 54
Data indicating the frequency f11 of the last channel is read from 00, and then the routine 100 is executed.

Therefore, in the same manner as in the case of "selection by ten-key", the frequency f11 received when the power was last turned off is selected and the data table is selected.
According to the result of referring to the DTBL, the reception mode and the bandwidth are selected corresponding to the frequency f11.

Therefore, when the power is turned on from off, the frequency f that was received when the power was last turned off is
11 is tuned in, the reception mode and the bandwidth corresponding to the frequency f11 are set, and the reception of the frequency f11 is performed.

<< Change of Reception Mode >> For example, when broadcasting or communication of a DSB signal is being received, the CPU 5
By referring to the data table DTBL in the routine 100, the detection circuit 17 is selected and the reception mode is set to the DSB reception mode.

However, if there is another radio wave in the band of the USB component or the LSB component of the DSB signal, a beat failure may occur. In such a case, even in the case of a DSB signal, setting to the USB reception mode or the LSB reception mode improves beat disturbance and the like, and makes it easier to listen to a target broadcast or communication.

The “change of reception mode” in this section is used in such a case and the like.
The reception mode set to BL is a case where reception is performed in a different reception mode.

That is, when the function key KFU is pressed while an arbitrary frequency f11 is being received, a key flag is set, and thereafter, for example, the first tuning key K01 functions as a reception mode change key. .

When the key K01 is pressed, the switch circuits 48 and 49 are switched in a predetermined order each time the key K01 is pressed, and the reception mode is switched between the DSB reception mode, the USB reception mode, and the LSB reception mode periodically. It switches to.

Therefore, by the above key operation, the broadcast signal currently being received can be received in a reception mode different from the reception mode set in the data table DTBL.

When the function key KFU is pressed again, the key flag is reset irrespective of the reception mode at that time, and thereafter the key K01 is set to the original key as described in the above <Tuning by tuning key>. It will act as a tuning key.

Even if the reception mode is changed in this way, the next time a tuning operation is performed, the data table DTBL will be displayed even if the reception frequency f11 after the tuning is the same as that before the tuning.
Are referred to, the function key KFU and the key K
The reception mode set by 01 is canceled.

<< Change in Bandwidth >> For example, when a medium-wave broadcast is being received, the CPU 51 refers to the data table DTBL in the routine 100, so that the intermediate frequency amplifier 16W is selected and the bandwidth is wide. Is set to

However, if there is another broadcast wave near the DSB signal, interference may occur. In such a case, if the intermediate frequency amplifier 16N is selected and the bandwidth is set to a narrow band, interference is improved, and the intended broadcast or communication becomes easier to listen to.

The term "change of bandwidth" in this section is used in such a case, and is a case where reception is performed with a bandwidth different from the bandwidth set in the data table DTBL.

That is, when the function key KFU is pressed while an arbitrary frequency f11 is being received, a key flag is set, and thereafter, for example, the second tuning key K02 functions as a key for changing the bandwidth. .

When the key K02 is pressed, the switch circuit 47 is switched each time the key K02 is pressed, and the bandwidth is switched between a wide band and a narrow band alternately.

Therefore, by this key operation, the currently received broadcast signal can be received with a bandwidth different from the bandwidth set in the data table DTBL.

When the function key KFU is pressed again, the key flag is reset irrespective of the bandwidth at that time, and thereafter, the key K02 is reset to the original key as described in the above <Tuning by tuning key>. It will act as a tuning key.

Even if the bandwidth is changed in this manner, the data table DTBL is referred to when the next tuning operation is performed, even if the reception frequency f11 after the tuning is the same as that before the tuning. Therefore, the bandwidth set by the function keys KFU and K02 is canceled.

<< Other >> In the above description, it is assumed that the data table DTBL of FIG.
This can be prepared in the RAM 54. Also, RA
When prepared in M54, the setting of the reception mode or the bandwidth can be changed.

In the above description, the intermediate frequency amplifiers 16W and 16N are selected according to the bandwidth. However, according to the bandwidth, a wide band intermediate frequency filter and a narrow band intermediate frequency filter are selected. The selected output may be supplied to an amplifier.

[0083]

According to the present invention, for each reception band,
Paying attention to the fact that the reception mode and the bandwidth are almost fixed, and inputting the reception frequency f11, the data table DT
By referring to the BL, the reception mode and the bandwidth are automatically set in accordance with the reception frequency f11.

Therefore, when receiving medium-wave broadcasting, short-wave broadcasting, or short-wave communication, the receiving mode is switched to the DSB receiving mode, USB receiving mode, or LSB receiving mode by manual operation in accordance with the transmission signal. There is no need to switch the bandwidth of the frequency amplifier according to the bandwidth of the transmission signal, the reception operation is easy, and even those who are not familiar with short-wave broadcasting,
Various broadcasts and communications can be easily received.

Also, during scan reception,
Since the reception mode and the bandwidth are automatically switched according to the reception frequency, the merits of scan reception can be fully utilized.

Further, the data table DTBL is stored in the ROM 52.
And the routine 100 only needs to be prepared, so that the cost is low.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of the present invention.

FIG. 2 is a flowchart illustrating an example of a channel selection routine.

FIG. 3 is a diagram illustrating an example of a data table.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 13 1st mixer circuit 14 1st intermediate frequency amplifier 15 2nd mixer circuit 16 2nd intermediate frequency amplifier 17 AM detection circuit 20 PLL 21 VCO 22 Variable frequency dividing circuit 31 VCXO 32 D / A converter 41 USB BFO 42 For LSB BFO 43 Mixer circuit 50 Microcomputer 100 Tuning routine KFC-KTE Operation keys

Claims (1)

(57) [Claims] 1. A super-heterodyne receiver for receiving a DSB signal, a USB signal, and an LSB signal as a reception signal, wherein the first intermediate frequency circuit has a pass bandwidth corresponding to the occupied bandwidth of the DSB signal. And a second intermediate frequency circuit having a pass bandwidth corresponding to the occupied bandwidth of the USB signal and the LSB signal; and selectively selecting the first intermediate frequency circuit and the second intermediate frequency circuit. A first switch circuit for effectively switching; a second switch for selectively and effectively extracting a BFO signal of a first frequency corresponding to the USB signal and a BFO signal of a second frequency corresponding to the LSB signal Circuit, a reception frequency band, and the reception frequency band is DS
A data table in which reception mode data indicating which of the B signal, the USB signal and the LSB signal is supported is set, and when selecting a station by setting a reception frequency, With reference to the data table, the data of the reception mode paired with the reception frequency band including the set reception frequency is extracted, and when the extracted data of the reception mode indicates the DSB signal, And switching control of the first switch circuit to select the first intermediate frequency circuit, and AM detection of an intermediate frequency signal obtained by selecting the first intermediate frequency circuit to extract an audio signal. When the data in the reception mode indicates the USB signal or the LSB signal, the first
And the second intermediate frequency circuit is selected by controlling the switching of the second switch circuit, and the second switch circuit is controlled to be switched in accordance with the data of the received reception mode, so that the first and second intermediate frequency circuits are controlled.
Extracting the BFO signal corresponding to the USB signal or the LSB signal indicated by the extracted reception mode data from among the BFO signals of the frequency, and selecting the extracted BFO signal and the second intermediate frequency circuit. Is supplied to the mixer circuit to extract the audio signal, and when the first predetermined key operation is performed, regardless of the switching result of the first switch circuit and the second switch circuit, By controlling the switching of the first and second switch circuits, the reception mode is sequentially changed to the reception mode of the DSB signal, the USB signal or the LSB signal, and when a second predetermined key operation is performed, Switching the first switch circuit irrespective of the selection result of the first intermediate frequency circuit and the second intermediate frequency circuit Please to superheterodyne receiver which is adapted to select alternately said first intermediate frequency circuit or the second intermediate frequency circuit.