A speech signal receiver circuit

Abstract

The utility model discloses a speech signal receiver circuit, its characterized in that, including the signal receiving circuit for receiving the signal of speech signal's frequency band, the frequency modulation circuit for carrying out the demodulation to speech signal's frequency band's signal, the frequency mixing frequency discrimination circuit for carrying out the separation to the signal after demodulation and the power amplification circuit of the original speech signal after filtering to the signal after separation and restoring, the utility model's advantage lies in: receiver not only can use in low frequency band, still can use in other frequency band, and the application range is wider.

Description

Technical Field

[0001] This utility model relates to the field of wireless transmission communication, and more specifically to a voice signal receiver circuit. Background Technology

[0002] There are two basic receiver architectures: superheterodyne and direct conversion. A superheterodyne receiver mixes or down-converts the received radio frequency (RF) signal with a local oscillator (LO) signal of a specific frequency, outputting a lower intermediate frequency (IF) modulated signal. The frequency of this IF signal is a fixed frequency difference between the LO signal and the received signal. Demodulation is then performed by a demodulator at the IF frequency after filtering and amplifying the IF signal.

[0003] In a direct-conversion receiver, the basic principle is the same as that of a heterodyne receiver. The difference lies in that the local oscillator frequency involved in mixing is not arbitrarily given, but equal to the carrier frequency. This results in an intermediate frequency (IF) of 0, eliminating image frequency and image interference. This scheme is often called the zero-IF scheme. The RF section of this scheme eliminates the image filter, and the IF filter becomes a low-pass filter, simplifying the system structure, reducing design and implementation difficulty, and saving costs. However, direct-conversion receivers have significant drawbacks. For example, because the local oscillator frequency is the same as the carrier frequency, it is prone to leakage; there is DC bias, which seriously affects subsequent circuits; it can only be used for demodulating amplitude-modulated signals, not frequency-modulated or phase-modulated signals; and it requires high local oscillator stability, so it is mostly used only in the low-frequency band. Therefore, most current direct-conversion receivers can only be used in the low-frequency band. Designing a superheterodyne voice signal receiver circuit is essential to allow for unrestricted frequency band usage and expand the application range. Utility Model Content

[0004] The technical problem to be solved by this invention is that most existing direct conversion receivers are only used in the low frequency band, resulting in a narrow application range.

[0005] This utility model solves the above-mentioned technical problems through the following technical means: a voice signal receiver circuit, including a signal receiving circuit for receiving signals in the frequency band where the voice signal is located, a frequency modulation circuit for demodulating the signals in the frequency band where the voice signal is located, a mixing and frequency discrimination circuit for separating the demodulated signals, and a power amplifier circuit for filtering the separated signals to restore the original voice signal.

[0006] This invention designs a voice signal receiver circuit based on a superheterodyne structure. The signal receiving circuit receives the signal in the frequency band of the voice signal, then demodulates it through a frequency modulation circuit, separates the signal through a frequency mixer and frequency discriminator circuit, and finally restores the original voice signal by filtering the separated signal through a power amplifier circuit. The frequency band of the voice signal can be low frequency or mid frequency depending on the input voice. Therefore, the signal receiving circuit receives low frequency or mid frequency signals in the frequency band of the voice signal. Thus, this invention can be used not only in the low frequency band but also in other frequency bands, and has a wide range of applications.

[0007] Furthermore, the signal receiving circuit includes a frequency selection unit, a first-stage amplification unit, and a second-stage amplification unit, which are connected sequentially.

[0008] Furthermore, the frequency selection unit includes an antenna E2, capacitors C31, C32, and C33, and a transformer T3. The antenna E2 is connected to one end of capacitor C31, the other end of capacitor C31, one end of capacitor C32, and the same-name terminal of the primary coil of transformer T3 are connected, the other end of capacitor C32 is connected to the opposite-name terminal of the primary coil of transformer T3, and one end of capacitor C33 is connected to the same-name terminal of the secondary coil of transformer T3.

[0009] Furthermore, the first-stage amplification unit includes a resistor R31, a transistor VT6, a capacitor C34, a resistor R32, and a capacitor C35. The other end of capacitor C33, one end of resistor R31, and the base of transistor VT6 are connected. The other end of resistor R31, the collector of transistor VT6, and one end of capacitor C35 are connected. The emitter of transistor VT6, one end of capacitor C34, and one end of resistor R32 are connected. The opposite-name terminal of the secondary coil of transformer T3, the other end of capacitor C34, the other end of resistor R32, and the other end of capacitor C35 are all connected and grounded.

[0010] Furthermore, the secondary amplification unit includes a transistor VT7, resistors R33, R34, and R35, and a capacitor C36. The emitter of transistor VT7 is connected to the other end of resistor R31. The base of transistor VT7 is connected to one end of resistor R33, one end of capacitor C35, and one end of resistor R35. The collector of transistor VT7 is connected to one end of resistor R34. The other end of resistor R34 is connected to the other end of resistor R35, and capacitor C36 is connected between them. The other ends of resistors R34 and R35 are both connected to the frequency modulation circuit. The opposite-name terminal of the secondary coil of transformer T3 is connected to the other end of resistor R33 and grounded.

[0011] Furthermore, the frequency modulation circuit includes a transformer T2, a chip U1, a capacitor C37, a resistor R36, a capacitor C49, sequentially numbered crystal oscillators JT3 to JT6, sequentially numbered capacitors C39 to C42, resistors R61, R41, R44, and capacitor C51. The same-name terminal of the primary winding of the transformer T2 is connected to the other end of resistor R34, and the opposite-name terminal of the primary winding of the transformer T2 is connected to the other end of resistor R35. The same-name terminal of the secondary winding of the transformer T2 is connected to the first pin of the chip U1. The secondary winding of the transformer T2... One end of the capacitor C42 is connected to pin 13 of chip U1; one end of capacitor C42 is connected to pin 2 of chip U1; the other end of capacitor C42 is grounded; one end of crystal oscillator JT4 is connected to pin 7 of chip U1; the other end of crystal oscillator JT4, pin 6 of chip U1, and pin 8 of chip U1 are all connected; one end of resistor R41 is connected to one end of crystal oscillator JT4; the other end of resistor R41 is connected to pin 10 of chip U1; one end of capacitor C51 is connected to pin 11 of chip U1; the other end of capacitor C51 is connected to pin 12 of chip U1.

[0012] One end of capacitor C37, one end of resistor R36, one end of capacitor C49, and pin 15 of chip U1 are connected; the other end of capacitor C49, one end of crystal oscillator JT3, and pin 16 of chip U1 are connected; one end of crystal oscillator JT6 is connected to pin 18 of chip U1; the other end of crystal oscillator JT6, pin 17, and pin 19 of chip U1 are connected; one end of capacitor C40 is connected to pin 21 of chip U1; the other end of capacitor C40, one end of capacitor C39, and pin 20 of chip U1 are connected; one end of capacitor C41 and pin 22 of chip U1 are connected... One end of the sliding rheostat R62 is connected; one end of the resistor R61 is connected to the twenty-third pin of the chip U1; one end of the crystal oscillator JT5 and one end of the resistor R44 are both connected to the twenty-fourth pin of the chip U1; the other ends of the capacitor C37, the resistor R36, the crystal oscillator JT3, the eighteenth pin of the chip U1, the capacitor C39, the capacitor C41, the sliding rheostat R62, the control terminal of the sliding rheostat R62, the resistor R61, the crystal oscillator JT5, and the resistor R44 are all connected to the neutral point of the main winding of the transformer T2.

[0013] Furthermore, the chip U1 is model number MC3362.

[0014] Furthermore, the frequency mixer and discriminator circuit includes a transformer T1, a resistor R38, a capacitor C43, a transistor VT8, a capacitor C46, ​​a resistor R63, a capacitor C64, a crystal oscillator JT2, a resistor R39, a capacitor C68, a variable capacitor C48, a capacitor C44, a capacitor C61, and a capacitor C62. The same-name terminal of the primary winding of the transformer T1 is connected to the fourth pin of the chip U1, and the opposite-name terminal of the primary winding of the transformer T1 is connected to the third pin of the chip U1. The same-name terminal of the secondary winding of the transformer T1, one end of the resistor R38, one end of the capacitor C43, one end of the resistor R39, and one end of the capacitor C44 are connected. The other end of the capacitor C44 is grounded, and the other end of the capacitor C43 is connected to the opposite-name terminal of the secondary winding of the transformer T1. The collector of the transistor VT8 is connected to... The neutral point of the secondary coil of transformer T1 is connected. The emitter of transistor VT8, one end of capacitor C46, ​​one end of resistor R63, and one end of capacitor C64 are connected. The other end of capacitor C64, the base of transistor VT8, one end of crystal oscillator JT2, and the other end of resistor R39 are connected. The other end of crystal oscillator JT2, one end of capacitor C68, and one end of variable capacitor C48 are connected. The other end of capacitor C46, ​​the other end of resistor R63, the other end of capacitor C68, and the other end of variable capacitor C48 are connected and grounded. The other end of resistor R38, the seventh pin of chip U1, the positive terminal of capacitor C61, and one end of capacitor C62 are all connected to the neutral point of the primary coil of transformer T2. The negative terminal of capacitor C61 and the other end of capacitor C62 are connected and grounded.

[0015] Furthermore, the power amplifier circuit includes a chip U2 and capacitors C55 to C58 numbered sequentially. The sixth pin of chip U2 is connected to the twenty-third pin of chip U1, and the eighth pin of chip U2 is grounded. The third pin of chip U2, one end of capacitor C62, the positive terminal of capacitor C57, and one end of capacitor C58 are connected to a +6V power supply. The negative terminal of capacitor C57 and the other end of capacitor C58 are connected to ground. The positive terminal of capacitor C55 is connected to the fourth pin of chip U2, and the negative terminal of capacitor C55 is grounded. The two ends of capacitor C56 are connected to a filter, and the output of the filter is connected to a speaker, which outputs a voice signal.

[0016] Furthermore, the chip U2 is model number LM386.

[0017] The advantages of this utility model are:

[0018] (1) This utility model designs a voice signal receiver circuit based on a superheterodyne structure. The signal receiving circuit receives the signal in the frequency band where the voice signal is located, and then demodulates it through a frequency modulation circuit. The signal is separated through a frequency mixer and frequency discriminator circuit. The separated signal is filtered by a power amplifier circuit to restore the original voice signal. The frequency band where the voice signal is located can be low frequency or medium frequency depending on the input voice. Therefore, the signal receiving circuit receives the low frequency signal or medium frequency signal in the frequency band where the voice signal is located. So this utility model can not only be used in the low frequency band, but also in other frequency bands, and has a wide range of applications.

[0019] (2) The signal receiving circuit of this utility model receives a small high-frequency signal. The transformer T3 and capacitor C32 form a frequency selection circuit to select the required frequency for reception, exclude signals of other frequency bands received by the antenna, so that the circuit resonant frequency is consistent with the received signal frequency, and reduce interference from other signals. Transistors VT6 and VT7 form a two-stage amplifier circuit to amplify the received signal and input it to the next stage.

[0020] (3) The frequency modulation circuit of this utility model uses chip U1 to generate a local oscillation that is consistent with the internal frequency of the transmitting part, which facilitates high-frequency small signal demodulation.

[0021] (4) The frequency mixing and frequency discrimination circuit of this utility model separates the intermediate signals through frequency mixing and frequency discrimination, which makes it easier for the subsequent stage to perform power amplification of the signal and then restore the voice signal, prevents signal overlap, and avoids inaccurate output results.

[0022] (5) The power amplifier circuit of this utility model amplifies the already separated signal output by the frequency mixing and frequency discrimination circuit through power amplification, increases the output current, and filters out the two different frequency signals loaded on the voice input signal by connecting a filter at the output end, restores the original voice signal, and outputs the voice signal through the speaker. Attached Figure Description

[0023] Figure 1 This is a structural block diagram of a voice signal receiver circuit disclosed in an embodiment of the present utility model;

[0024] Figure 2 This is a schematic diagram of the signal receiving circuit in a voice signal receiver circuit disclosed in an embodiment of the present utility model;

[0025] Figure 3 This is a schematic diagram of the frequency modulation circuit in a voice signal receiver circuit disclosed in an embodiment of the present utility model;

[0026] Figure 4 This is a schematic diagram of a mixing and frequency discrimination circuit in a voice signal receiver circuit disclosed in an embodiment of the present utility model;

[0027] Figure 5 This is a schematic diagram of a power amplifier circuit in a voice signal receiver circuit disclosed in an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below in conjunction with the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0029] like Figure 1 As shown, a voice signal receiver circuit includes a signal receiving circuit 5 for receiving signals in the frequency band where the voice signal is located, a frequency modulation circuit 6 for demodulating the signals in the frequency band where the voice signal is located, a mixing and frequency discrimination circuit 7 for separating the demodulated signals, and a power amplifier circuit 8 for filtering the separated signals to restore the original voice signal.

[0030] like Figure 2As shown, the signal receiving circuit 5 includes an antenna E2, capacitors C31 to C36 numbered sequentially, a transformer T3, resistors R31 to R35 numbered sequentially, a transistor VT6, and a transistor VT7. Antenna E2 is connected to one end of capacitor C31. The other end of capacitor C31, one end of capacitor C32, and the same-name terminal of the main winding of transformer T3 are connected. The other end of capacitor C32 is connected to the opposite-name terminal of the main winding of transformer T3. One end of capacitor C33 is connected to the same-name terminal of the secondary winding of transformer T3. The other end of capacitor C33, one end of resistor R31, and the base of transistor VT6 are connected. The other end of resistor R31, the... The collector of transistor VT6, the emitter of transistor VT7, one end of capacitor C35, one end of resistor R33, and one end of resistor R35 are connected together. The emitter of transistor VT6, one end of capacitor C34, and one end of resistor R32 are connected together. The collector of transistor VT7 is connected to one end of resistor R34. The other end of resistor R34 and the other end of resistor R35 are connected to capacitor C36. The other ends of resistor R34 and resistor R35 are both connected to frequency modulation circuit 6. The opposite-name terminal of the secondary coil of transformer T3, the other end of capacitor C34, the other end of resistor R32, the other end of capacitor C35, and the other end of resistor R33 are all connected and grounded. The signal receiving circuit 5 receives a small high-frequency signal. The transformer T3 and capacitor C32 form a frequency selection circuit to select the required frequency for reception, eliminating signals from other frequency bands received by the antenna, so that the circuit resonant frequency is consistent with the received signal frequency, reducing interference from other signals. Transistors VT6 and VT7 form a two-stage amplifier circuit to amplify the received signal and input it to the next stage.

[0031] like Figure 3As shown, the frequency modulation circuit 6 includes a transformer T2, a chip U1, a capacitor C37, a resistor R36, a capacitor C49, crystal oscillators JT3 to JT6 numbered sequentially, capacitors C39 to C42 numbered sequentially, resistors R61, R41, R44, and capacitor C51. The chip U1 is model MC3362. The same-name terminal of the primary winding of transformer T2 is connected to the other end of resistor R34, and the opposite-name terminal of the primary winding of transformer T2 is connected to the other end of resistor R35. The same-name terminal of the secondary winding of transformer T2 is connected to the first pin of chip U1, and the opposite-name terminal of the secondary winding of transformer T2 is connected to the thirteenth pin of chip U1. One end of capacitor C42 is connected to the second pin of chip U1, and the other end of capacitor C42 is grounded. One end of crystal oscillator JT4 is connected to the seventh pin of chip U1, and the other end of crystal oscillator JT4, the sixth pin of chip U1, and the eighth pin of chip U1 are all connected. One end of resistor R41 is connected to one end of crystal oscillator JT4, and the other end of resistor R41 is connected to the tenth pin of chip U1. One end of capacitor C51 is connected to the eleventh pin of chip U1, and the other end of capacitor C51 is connected to the twelfth pin of chip U1.

[0032] One end of capacitor C37, one end of resistor R36, one end of capacitor C49, and pin 15 of chip U1 are connected; the other end of capacitor C49, one end of crystal oscillator JT3, and pin 16 of chip U1 are connected; one end of crystal oscillator JT6 is connected to pin 18 of chip U1; the other end of crystal oscillator JT6, pin 17, and pin 19 of chip U1 are connected; one end of capacitor C40 is connected to pin 21 of chip U1; the other end of capacitor C40, one end of capacitor C39, and pin 20 of chip U1 are connected; one end of capacitor C41 and pin 22 of chip U1 are connected... One end of the sliding rheostat R62 is connected; one end of the resistor R61 is connected to the twenty-third pin of the chip U1; one end of the crystal oscillator JT5 and one end of the resistor R44 are both connected to the twenty-fourth pin of the chip U1; the other ends of the capacitor C37, the resistor R36, the crystal oscillator JT3, the eighteenth pin of the chip U1, the capacitor C39, the capacitor C41, the sliding rheostat R62, the control terminal of the sliding rheostat R62, the resistor R61, the crystal oscillator JT5, and the resistor R44 are all connected to the neutral point of the main winding of the transformer T2. The frequency modulation circuit 6 uses chip U1 to generate a local oscillation consistent with the internal frequency of the transmitting section, facilitating the demodulation of high-frequency small signals. The input high-frequency signal, after passing through the signal receiving circuit 5, enters the first mixer built into the MC3362 for amplification and conversion into a first intermediate frequency (IF) signal of 10.7 MHz. After being filtered by an external bandpass ceramic filter, the first IF signal is further amplified and mixed in the second mixer built into the MC3362, converting it into a second IF signal of 455 kHz. The second IF signal is then filtered again by an external bandpass ceramic filter and input to the internal limiting amplifier and frequency detection circuit, before being output to the next stage mixer-discriminator circuit 7. The mixer-discriminator circuit 7 recovers the message signal and separates the signal, which is then output by the speaker.

[0033] like Figure 4As shown, the frequency mixer and frequency discriminator circuit 7 includes a transformer T1, a resistor R38, a capacitor C43, a transistor VT8, a capacitor C46, ​​a resistor R63, a capacitor C64, a crystal oscillator JT2, a resistor R39, a capacitor C68, a variable capacitor C48, a capacitor C44, a capacitor C61, and a capacitor C62. The same-name terminal of the primary winding of the transformer T1 is connected to the fourth pin of the chip U1, and the opposite-name terminal of the primary winding of the transformer T1 is connected to the third pin of the chip U1. The same-name terminal of the secondary winding of the transformer T1, one end of the resistor R38, one end of the capacitor C43, one end of the resistor R39, and one end of the capacitor C44 are connected together. The other end of the capacitor C44 is grounded, and the other end of the capacitor C43 is connected to the opposite-name terminal of the secondary winding of the transformer T1. The collector of the transistor VT8 is connected to the variable frequency discriminator JT2. The neutral point of the secondary coil of transformer T1 is connected. The emitter of transistor VT8, one end of capacitor C46, ​​one end of resistor R63, and one end of capacitor C64 are connected. The other end of capacitor C64, the base of transistor VT8, one end of crystal oscillator JT2, and the other end of resistor R39 are connected. The other end of crystal oscillator JT2, one end of capacitor C68, and one end of variable capacitor C48 are connected. The other end of capacitor C46, ​​the other end of resistor R63, the other end of capacitor C68, and the other end of variable capacitor C48 are connected and grounded. The other end of resistor R38, pin 7 of chip U1, the positive terminal of capacitor C61, and one end of capacitor C62 are all connected to the neutral point of the primary coil of transformer T2. The negative terminal of capacitor C61 and the other end of capacitor C62 are connected and grounded. The mixer and frequency discriminator circuit 7 separates the intermediate signals through mixing and discrimination, facilitating the subsequent power amplification of the signals for voice signal restoration, preventing signal overlap, and avoiding inaccurate output results.

[0034] like Figure 5As shown, the power amplifier circuit 8 includes chip U2 and capacitors C55 to C58 numbered sequentially. Chip U2 is an LM386. Pin 6 of chip U2 is connected to pin 23 of chip U1, and pin 8 of chip U2 is grounded. Pin 3 of chip U2, one end of capacitor C62, the positive terminal of capacitor C57, and one end of capacitor C58 are connected to a +6V power supply. The negative terminal of capacitor C57 and the other end of capacitor C58 are connected to ground. The positive terminal of capacitor C55 is connected to pin 4 of chip U2, and the negative terminal of capacitor C55 is grounded. Both ends of capacitor C56 are connected to a filter, and the output of the filter is connected to a speaker, which outputs a voice signal. The power amplifier circuit 8 amplifies the separated signal output from the mixer-discriminator circuit 7, increasing the output current. By connecting two filters at the output, it filters out the two different frequency signals applied to the dual-channel voice input signals, restoring the original dual-channel voice signals, which are then output through speakers. The number of filters and the selection of the filtering frequency bands are determined by the input speech signal. If there are two speech signals, two filters are used to filter out the signals loaded on the two speech signals respectively, and the two speech signals are restored. If there is only one speech signal, only one filter needs to be set to filter out the signals loaded on that speech signal and restore the original speech signal.

[0035] Based on the above technical solutions, this utility model designs a voice signal receiver circuit based on a superheterodyne structure. The signal receiving circuit 5 receives the signal in the frequency band where the voice signal is located, then demodulates it through the frequency modulation circuit 6, separates the signal through the mixing and frequency discrimination circuit 7, and finally restores the original voice signal by filtering the separated signal through the power amplifier circuit 8. The frequency band where the voice signal is located can be low frequency or mid frequency depending on the input voice. Therefore, the signal receiving circuit 5 receives the low frequency signal or mid frequency signal in the frequency band where the voice signal is located. Thus, this utility model can not only be used in the low frequency band, but also in other frequency bands, and has a wide range of applications.

[0036] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A voice signal receiver circuit, characterized in that, The system includes a signal receiving circuit for receiving signals in the same frequency band as the voice signal, a frequency modulation circuit for demodulating the signals in the same frequency band as the voice signal, a mixing and frequency discrimination circuit for separating the demodulated signals, and a power amplifier circuit for filtering the separated signals to restore the original voice signal. The signal receiving circuit includes a frequency selection unit, a first-stage amplification unit, and a second-stage amplification unit, which are connected in sequence. The frequency selection unit includes an antenna E2, capacitors C31, C32, and C33, and a transformer T3. Antenna E2 is connected to one end of capacitor C31, the other end of capacitor C31, one end of capacitor C32, and the same-name terminal of the main coil of transformer T3 are connected, the other end of capacitor C32 is connected to the opposite-name terminal of the main coil of transformer T3, and one end of capacitor C33 is connected to the same-name terminal of the secondary coil of transformer T3.

2. The voice signal receiver circuit according to claim 1, characterized in that, The first-stage amplification unit includes a resistor R31, a transistor VT6, a capacitor C34, a resistor R32, and a capacitor C35. The other end of capacitor C33, one end of resistor R31, and the base of transistor VT6 are connected. The other end of resistor R31, the collector of transistor VT6, and one end of capacitor C35 are connected. The emitter of transistor VT6, one end of capacitor C34, and one end of resistor R32 are connected. The opposite-name terminal of the secondary coil of transformer T3, the other end of capacitor C34, the other end of resistor R32, and the other end of capacitor C35 are all connected and grounded.

3. The voice signal receiver circuit according to claim 2, characterized in that, The secondary amplification unit includes a transistor VT7, resistors R33, R34, and R35, and a capacitor C36. The emitter of transistor VT7 is connected to the other end of resistor R31. The base of transistor VT7 is connected to one end of resistor R33, one end of capacitor C35, and one end of resistor R35. The collector of transistor VT7 is connected to one end of resistor R34. The other end of resistor R34 is connected to the other end of resistor R35, and capacitor C36 is connected between them. The other ends of resistors R34 and R35 are both connected to the frequency modulation circuit. The opposite-name terminal of the secondary coil of transformer T3 is connected to the other end of resistor R33 and grounded.

4. The voice signal receiver circuit according to claim 3, characterized in that, The frequency modulation circuit includes a transformer T2, a chip U1, a capacitor C37, a resistor R36, a capacitor C49, sequentially numbered crystal oscillators JT3 to JT6, sequentially numbered capacitors C39 to C42, resistors R61, R41, R44, and capacitor C51. The same-name terminal of the primary winding of transformer T2 is connected to the other end of resistor R34, and the opposite-name terminal of the primary winding of transformer T2 is connected to the other end of resistor R35. The same-name terminal of the secondary winding of transformer T2 is connected to the first pin of chip U1, and the opposite-name terminal of the secondary winding of transformer T2 is connected to the first pin of chip U1. One end of capacitor C42 is connected to pin 13 of chip U1, and the other end of capacitor C42 is connected to ground. One end of crystal oscillator JT4 is connected to pin 7 of chip U1, and the other end of crystal oscillator JT4, pin 6 of chip U1, and pin 8 of chip U1 are all connected. One end of resistor R41 is connected to one end of crystal oscillator JT4, and the other end of resistor R41 is connected to pin 10 of chip U1. One end of capacitor C51 is connected to pin 11 of chip U1, and the other end of capacitor C51 is connected to pin 12 of chip U1. One end of capacitor C37, one end of resistor R36, one end of capacitor C49, and pin 15 of chip U1 are connected; the other end of capacitor C49, one end of crystal oscillator JT3, and pin 16 of chip U1 are connected; one end of crystal oscillator JT6 is connected to pin 18 of chip U1; the other end of crystal oscillator JT6, pin 17, and pin 19 of chip U1 are connected; one end of capacitor C40 is connected to pin 21 of chip U1; the other end of capacitor C40, one end of capacitor C39, and pin 20 of chip U1 are connected; one end of capacitor C41 and pin 22 of chip U1 are connected... One end of the sliding rheostat R62 is connected; one end of the resistor R61 is connected to the twenty-third pin of the chip U1; one end of the crystal oscillator JT5 and one end of the resistor R44 are both connected to the twenty-fourth pin of the chip U1; the other ends of the capacitor C37, the resistor R36, the crystal oscillator JT3, the eighteenth pin of the chip U1, the capacitor C39, the capacitor C41, the sliding rheostat R62, the control terminal of the sliding rheostat R62, the resistor R61, the crystal oscillator JT5, and the resistor R44 are all connected to the neutral point of the main winding of the transformer T2.

5. A voice signal receiver circuit according to claim 4, characterized in that, The chip U1 is model number MC3362.

6. A voice signal receiver circuit according to claim 4, characterized in that, The frequency mixing and discrimination circuit includes a transformer T1, a resistor R38, a capacitor C43, a transistor VT8, a capacitor C46, ​​a resistor R63, a capacitor C64, a crystal oscillator JT2, a resistor R39, a capacitor C68, a variable capacitor C48, a capacitor C44, a capacitor C61, and a capacitor C62. The same-name terminal of the primary winding of transformer T1 is connected to the fourth pin of chip U1, and the opposite-name terminal of the primary winding of transformer T1 is connected to the third pin of chip U1. The same-name terminal of the secondary winding of transformer T1, one end of resistor R38, one end of capacitor C43, one end of resistor R39, and one end of capacitor C44 are connected together. The other end of capacitor C44 is grounded, and the other end of capacitor C43 is connected to the opposite-name terminal of the secondary winding of transformer T1. The collector of transistor VT8 is connected to the transformer... The neutral point of the secondary coil of T1 is connected. The emitter of transistor VT8, one end of capacitor C46, ​​one end of resistor R63, and one end of capacitor C64 are connected. The other end of capacitor C64, the base of transistor VT8, one end of crystal oscillator JT2, and the other end of resistor R39 are connected. The other end of crystal oscillator JT2, one end of capacitor C68, and one end of variable capacitor C48 are connected. The other end of capacitor C46, ​​the other end of resistor R63, the other end of capacitor C68, and the other end of variable capacitor C48 are connected and grounded. The other end of resistor R38, the seventh pin of chip U1, the positive terminal of capacitor C61, and one end of capacitor C62 are all connected to the neutral point of the primary coil of transformer T2. The negative terminal of capacitor C61 and the other end of capacitor C62 are connected and grounded.

7. A voice signal receiver circuit according to claim 6, characterized in that, The power amplifier circuit includes chip U2 and capacitors C55 to C58 numbered sequentially. The sixth pin of chip U2 is connected to the twenty-third pin of chip U1, and the eighth pin of chip U2 is grounded. The third pin of chip U2, one end of capacitor C62, the positive terminal of capacitor C57, and one end of capacitor C58 are connected to a +6V power supply. The negative terminal of capacitor C57 and the other end of capacitor C58 are connected to ground. The positive terminal of capacitor C55 is connected to the fourth pin of chip U2, and the negative terminal of capacitor C55 is grounded. The two ends of capacitor C56 are connected to a filter, and the output of the filter is connected to a speaker, which outputs a voice signal.

8. A voice signal receiver circuit according to claim 7, characterized in that, The chip U2 is model LM386.

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