Short-wave receiving and amplifying circuit capable of realizing cascade transmission and short-wave communication system

Abstract

The invention belongs to the technical field of radio frequency amplification circuits, and particularly discloses a short-wave receiving amplification circuit capable of realizing cascade transmission and a short-wave communication system. According to the invention, direct current and interference in a previous-level signal are filtered through the filtering module, a pure radio frequency signal is obtained, and a foundation is laid for subsequent processing; the signal strength is improved through the amplification module, and single-stage transmission attenuation is overcome; the key point is that the balance gain module applies gain processing which is compensated for the loss characteristic of a transmission link to the amplified signal, so that the signal strength can be accurately matched with the actual loss of the line, and the problem that a fixed gain mode cannot adapt to the multi-stage series accumulated loss is solved. Compared with the prior art, the scheme realizes stable cascade transmission of short-wave signals through cooperative work of the modules, and remarkably improves the transmission distance and reliability of the system through dynamic compensation accumulated loss.

Description

Technical Field

[0001] This application belongs to the field of radio frequency amplifier circuit technology, specifically relating to a cascaded shortwave receiving amplifier circuit and a shortwave communication system. Background Technology

[0002] Shortwave communication is a medium- to long-range communication method that achieves beyond-line-of-sight communication through the reflection of electromagnetic waves between the ionosphere and the ground, offering numerous advantages. Shortwave reception is a crucial component of shortwave communication systems. In practical applications, the receiving antenna often only requires the simplest structural form, such as a shortwave whip antenna or a small loop antenna. However, to achieve impedance matching and thus improve the transmission distance of the received signal, these types of antennas often require the assistance of amplifier circuits. This amplifier circuitry enables shortwave broadband active matching and provides a certain gain to the shortwave received signal to overcome line transmission losses.

[0003] To minimize noise introduced by transmission lines, traditional amplifier circuits typically mount a preamplifier close to the antenna root to ensure a high signal-to-noise ratio (SNR) at the input. However, as the signal transmits to downstream equipment, its strength gradually weakens due to line losses, leading to a decrease in the SNR. Furthermore, traditional circuits cannot implement repeater cascading, limiting the maximum transmission distance to the preamplifier's gain. Simply increasing the gain can easily cause saturation distortion in low-frequency shortwave signals. In addition, since shortwave signal losses in transmission lines increase with frequency, and traditional amplifier circuits offer uniform gain across all frequencies, they cannot specifically compensate for transmission losses at different frequencies. This results in a widening difference in amplitude between different frequency signals with increasing transmission distance, posing greater challenges to signal processing at the receiver.

[0004] Therefore, simply increasing the gain of traditional amplifier circuits cannot effectively overcome the limitation of transmission distance. We must seek other more effective technical methods to achieve reliable long-distance transmission of shortwave signals. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this application is to provide a cascaded shortwave receiving amplifier circuit, which aims to solve the problem that the long-distance transmission of shortwave signals is currently limited by the gain mode and cannot be cascaded, making it difficult to compensate for line losses and resulting in poor reliability.

[0006] The first aspect of this application relates to a cascaded shortwave receiver amplifier circuit, comprising: a first port, a filtering module, an amplification module, an equalization gain module, and a second port; the first port is connected to the input terminal of the filtering module; the output terminal of the filtering module is also connected to the first input terminal of the amplification module; the output terminal of the amplification module is connected to the input terminal of the equalization gain module; the output terminal of the equalization gain module is connected to the second port; the first port is used to receive the signal from the previous stage and transmit it to the filtering module; the filtering module is used to filter out DC and interference components in the previous stage signal, generate and transmit an RF signal to the amplification module; the amplification module is used to amplify the RF signal and transmit it to the equalization gain module; the equalization gain module is used to perform gain processing on the amplified RF signal, generate a gain signal and output it to the second port to achieve multi-stage cascading; the gain processing provides a gain that compensates for the loss characteristics of the current signal transmission link.

[0007] In one embodiment, the cascadeable shortwave receiving amplifier circuit further includes: a DC separation module; the input terminal of the DC separation module is connected to a second port; the first output terminal of the DC separation module is connected to a first port; both the first port and the second port are composite ports for radio frequency and DC signals; the DC separation module is used to extract the DC component from the mixed signal of the second port and generate a first DC voltage signal to be transmitted to the first port; the first port is used to transmit the radio frequency DC signal composed of the first DC voltage signal and the previous stage signal to a filtering module; the filtering module is used to receive the DC voltage signal for power supply, and filter out the interference components and DC components of the radio frequency DC signal, generate and transmit the radio frequency signal to the amplification module.

[0008] In one embodiment, the cascadeable shortwave receiving amplifier circuit further includes: a power supply adjustment module; the input terminal of the power supply adjustment module is connected to the second output terminal of the DC separation module, and the output terminal of the power supply adjustment module is connected to the power supply terminal of the amplifier module; the DC separation module is used to extract the DC component in the mixed signal of the second port and generate a second DC voltage signal to the power supply terminal of the amplifier module to provide DC bias.

[0009] In one embodiment, the cascadeable shortwave receiving amplifier circuit further includes a limiting module. The input terminal of the limiting module is connected to the output terminal of the filtering module. The limiting module is used to restrict the flow of the radio frequency signal to the amplification module when the amplitude of the radio frequency signal output by the filtering module exceeds a preset amplitude.

[0010] In one embodiment, the filtering module includes: a first capacitor and a first inductor; a first terminal of the first capacitor is connected to a first port, and a second terminal of the first capacitor is connected to the first terminal of the first inductor, the input terminal of the amplification module, and the input terminal of the limiting module; the second terminal of the first inductor is grounded; the limiting module includes a first diode and a second diode; the second terminal of the first capacitor is connected to the cathode of the first diode and the anode of the second diode; the anode of the first diode and the cathode of the second diode are both grounded.

[0011] In one embodiment, the amplification module includes: a second capacitor, an amplification chip, a third capacitor, a first resistor, a first filter capacitor, a second filter capacitor, and an RF choke loop; the first terminal of the second capacitor is connected to the output terminal of the filter module; the second terminal of the second capacitor is connected to the input terminal of the amplification chip; the output terminal of the amplification chip is connected to the first terminal of the third capacitor; the second terminal of the third capacitor is connected to the input terminal of the equalization gain module; the power supply terminal of the amplification chip is connected to the first terminals of the first and second filter capacitors respectively; the first terminals of the first and second filter capacitors are also grounded; the second terminals of the first and second filter capacitors are connected to the first terminal of the first resistor and the first terminal of the RF choke loop respectively; the second terminal of the first resistor is connected to the power supply; the second terminal of the RF choke loop is connected to the output terminal of the amplification chip.

[0012] In one embodiment, the equalization gain module includes: a second resistor, a third resistor, a fourth resistor, a fourth capacitor, a second inductor, and a fifth capacitor; the first end of the second resistor is connected to the output terminal of the amplification module and the first end of the fourth capacitor respectively; the second end of the second resistor is connected to the first end of the third resistor and the first end of the fourth resistor respectively; the second end of the third resistor is connected to the first end of the second inductor; the second end of the second inductor is grounded; the second end of the fourth resistor is connected to the second end of the fourth capacitor and the first end of the fifth capacitor respectively; the second end of the fifth capacitor is connected to a second port.

[0013] In one embodiment, the DC-DC separation module includes: a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, a seventh inductor, an eighth inductor, a sixth capacitor, and a seventh capacitor; the third inductor, the fourth inductor, the fifth inductor, the sixth inductor, the seventh inductor, and the eighth inductor are connected in series, with the first end of the series connection connected to the second port; the last end of the series connection is connected to the first port; the series terminals of the fifth inductor and the sixth inductor are respectively connected to the first terminal of the sixth capacitor, the input terminal of the power supply regulation module, and the first terminal of the seventh capacitor; the second terminal of the sixth capacitor is grounded; the second terminal of the seventh capacitor is grounded.

[0014] In one embodiment, the power supply regulation module includes: a voltage regulator chip, a third filter capacitor, and an output capacitor; the input terminal of the voltage regulator chip is connected to the second output terminal of the DC-DC separation module and the first terminal of the third filter capacitor respectively; the second terminal of the third filter capacitor is grounded; the output terminal of the voltage regulator chip is connected to the power supply terminal of the amplification module and the first terminal of the output capacitor respectively; the second terminal of the output capacitor is grounded; the voltage regulator chip is used to convert the input terminal voltage into a bias voltage as a power input to the amplification module.

[0015] The second aspect of this application relates to a shortwave communication system, which includes: an antenna and a plurality of cascaded shortwave receiving amplifier circuits as described in the first aspect; each cascaded shortwave receiving amplifier circuit is connected end-to-end through a cable of a preset length to form a transmission network; the input end of the transmission network is connected to the antenna.

[0016] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: This application employs a filtering module to remove DC and interference from the previous stage signal, thus obtaining a clean RF signal and providing a distortion-free signal foundation for subsequent amplification. The amplification module then amplifies this RF signal, directly increasing its strength and overcoming the inherent attenuation in single-stage transmission. Furthermore, an equalization gain module is used to compensate for the transmission link loss characteristics of the amplified signal, ensuring that the signal strength accurately matches the actual line loss. This effectively solves the problem of degraded signal reliability caused by the inability of fixed gain methods to adapt to the cumulative loss of multiple series stages.

[0017] Compared with existing technologies, through the synergistic effect of the above modules, this solution not only achieves stable cascading of shortwave signals in long-distance transmission, but also significantly improves the reliability and transmission distance of the entire transmission system by dynamically compensating for accumulated losses. Attached Figure Description

[0018] Figure 1 This is one of the structural block diagrams of the cascaded shortwave receiving amplifier circuit provided in the embodiments of this application; Figure 2 This is one of the circuit topologies of the cascaded shortwave receiving amplifier circuit provided in the embodiments of this application; Figure 3 This is the second structural block diagram of the cascaded shortwave receiving amplifier circuit provided in the embodiments of this application; Figure 4 This is the second circuit topology diagram of the cascaded shortwave receiving amplifier circuit provided in the embodiments of this application; Figure 5 This is a circuit topology diagram of the power supply regulation module provided in the embodiments of this application.

[0019] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: P1 is the first port; 10 is the filter module; 20 is the amplifier module; 30 is the equalization gain module; P2 is the second port; 40 is the DC-DC separation module; 50 is the power supply regulation module; C1 is the first capacitor; L1 is the first inductor; D1 is the first diode; D2 is the second diode; C2 is the second capacitor; U1 is the amplifier chip; C3 is the third capacitor; R1 is the first resistor; C11 is the first filter capacitor; C12 is the second filter capacitor; RFC is the RF choke ring; R2 is the second resistor; R3 is the third resistor; R4 is the fourth resistor; C4 is the fourth capacitor; L2 is the second inductor; C5 is the fifth capacitor; L3 is the third inductor; L4 is the fourth inductor; L5 is the fifth inductor; L6 is the sixth inductor; L7 is the seventh inductor; L8 is the eighth inductor; C6 is the sixth capacitor; C7 is the seventh capacitor; U2 is the voltage regulator chip; C13 is the third filter capacitor; C14 is the output capacitor; C15 is the bypass capacitor. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In this application, the symbol " / " indicates that the related objects are in an "or" relationship, for example, A / B means A or B.

[0022] In this application, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages. The term "connection" in this application can refer to a direct circuit connection or signal transmission via a communication protocol.

[0023] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0024] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0025] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0026] Currently, traditional shortwave receiver amplifier circuits cannot be cascaded in multiple stages for relay purposes. Furthermore, the gain of such amplifier circuits is the same for the entire shortwave frequency band, which cannot effectively compensate for the signal transmission loss. Simply increasing the gain of traditional amplifier circuits cannot effectively solve the problem of limited transmission distance of received signals.

[0027] Based on this, this application proposes an embodiment of a cascaded shortwave receiving amplifier circuit. Please refer to... Figure 1 , Figure 1 This is one of the structural block diagrams of the cascaded shortwave receiving amplifier circuit provided in the embodiments of this application.

[0028] In this embodiment, the cascaded shortwave receiving amplifier circuit includes: a first port P1, a filtering module 10, an amplification module 20, an equalization gain module 30, and a second port P2.

[0029] It should be noted that the first port P1 is connected to the input of the filter module; the output of the filter module is also connected to the first input of the amplifier module 20; the output of the amplifier module 20 is connected to the input of the equalization gain module 30; and the output of the equalization gain module 30 is connected to the second port P2.

[0030] It should be noted that the first port P1 is the entry point of the entire cascaded shortwave receiving amplifier circuit (hereinafter referred to as the "cascaded circuit"), mainly used to receive the signal from the previous stage and transmit it to the filtering module. This previous stage can be an antenna or another identical cascaded circuit. This open definition of the input signal source conceptually establishes a modular and scalable communication relay architecture, in which each cascaded circuit is a fully functional, standard-interface independent unit. When long-distance relay is required, multiple such units can be connected end-to-end through their P1 and P2 ports to construct a stable signal amplification link, enabling the signal to be transmitted in a relay manner to a distance far exceeding the capability of a single amplifier.

[0031] It should be noted that the first port P1 and the second port P2 in this embodiment are designed as a combined radio frequency (RF) and DC signal port. This means that a single port simultaneously undertakes two independent transmission tasks: one is to transmit downlink RF signals, i.e., shortwave communication signals that need to be amplified and relayed; the other is to transmit uplink DC power supply signals. This combined port design is the key physical basis for the seamless and simple multi-stage cascading of this circuit.

[0032] Specifically, in a cascaded system consisting of multiple such cascaded circuits, DC power can be transmitted along with radio frequency (RF) signals through the same pair of transmission lines, such as a coaxial cable. Based on this, a separate power supply can be introduced to power the devices in the cascaded circuit. To achieve this, a key passive component must be added inside the circuit: an RF choke (RFC) and a DC blocking capacitor. The specific implementation principle is as follows: Inside the first port P1, the power input line and the RF signal line first converge. After convergence, an RF choke is connected in series in the DC power supply path. It has extremely low impedance to DC, allowing it to pass smoothly, but presents extremely high impedance to high-frequency RF signals, thus preventing RF signals from entering the power supply and causing losses and radiation. Simultaneously, a DC blocking capacitor is connected in series in the RF signal path. Its function is the opposite of the choke; it allows RF signals to pass unimpeded but completely blocks DC, thus preventing the DC bias voltage at the port from affecting the operation of the preceding circuit.

[0033] Understandably, this approach, where a separate power supply enters from the first port P1, presents both advantages and disadvantages in engineering applications. Its core advantage lies in simplified system wiring; the entire cascaded system requires only a single cable carrying both RF signals and DC power, reducing complexity and cost. However, its main drawback is the introduction of potential interference risks. Noise on the power line can enter the highly sensitive RF receiver front-end through common-path coupling, thereby degrading the system's noise figure and receiver sensitivity. Therefore, this design places higher demands on circuit design.

[0034] It should be noted that the filtering module 10, as the first-stage processing unit after the RF signal is received, primarily functions to precisely filter and purify the previous-stage signal received from the first port P1, which may contain various mixed components. Specifically, it systematically filters out all non-target components in the signal through a specific internally integrated filtering network: First, it completely removes any DC components or low-frequency bias voltages that may exist in the signal, ensuring that the signal transmitted to the subsequent stage is a pure AC RF signal with zero DC components. This operation effectively prevents DC components from interfering with the static operating point of the amplification module 20, avoids potential saturation distortion risks, and lays a solid foundation for the stable cascading of multi-stage circuits.

[0035] Understandably, the filter module 10 can employ an LC network, utilizing its bandpass frequency response characteristics to strongly suppress out-of-band interference and noise outside the shortwave band. This includes interference from adjacent channels, natural noise, and other spurious signals, thereby significantly improving the signal-to-noise ratio and protecting the subsequent amplification module from nonlinear distortion caused by strong interference. After this module's deep purification process, a clean and stable target RF signal is generated and transmitted to the amplification module 20, providing crucial front-end assurance for the entire cascaded amplifier circuit to achieve its high linearity and low noise performance goals.

[0036] It should be noted that the amplification module 20 is used to amplify the radio frequency signal and transmit it to the equalization gain module 30. The amplification module 20 utilizes one or more internal amplification units, typically composed of active devices such as transistors, to linearly and with low noise amplify the power of the weak signal. Its core purpose is to compensate for the inherent losses incurred by the signal during its spatial transmission path and when passing through the front-end filtering network, thereby significantly improving the signal amplitude and driving capability.

[0037] Understandably, the amplified signal maintains a high signal-to-noise ratio and possesses sufficient strength for effective processing by the subsequent equalization gain module 30. The performance of the amplification module 20, especially its gain flatness, linearity, and noise figure, directly determines the signal-to-noise ratio floor, dynamic range, and distortion accumulation degree of the entire cascaded circuit, and is crucial to whether this circuit can achieve high-quality, long-distance relay transmission.

[0038] In addition, a limiting module can be introduced between the filtering module 10 and the amplification module 20. The input of the limiting module is connected to the output of the filtering module 10.

[0039] It should be noted that the limiting module is used to restrict the flow of the RF signal to the amplification module 20 when the amplitude of the RF signal output by the filtering module exceeds a preset amplitude. The limiting module continuously monitors the instantaneous amplitude of the RF signal from the filtering module 10 after filtering out major interference. When the peak voltage of the signal is lower than a preset safety threshold, the limiting module has almost no effect on the signal passage and is considered a transparent channel. However, once the signal amplitude is detected to exceed this preset threshold, the limiting module will immediately activate its limiting mechanism. At this time, a low-impedance path can be instantaneously introduced in the signal path to quickly guide the dangerous overload signal energy to the ground terminal, achieving effective isolation.

[0040] It should be noted that the equalization gain module 30 is used to perform gain processing on the amplified RF signal and generate a gain signal output to the second port P2 to realize multi-stage cascading; the gain processing is to provide a gain that compensates for the loss characteristics of the current signal transmission link.

[0041] It should be noted that the provided gain is not constant across the entire frequency band, but is designed to precisely compensate for the actual loss characteristics of the signal in the current transmission link. Specifically, when shortwave signals are transmitted through channels such as the ionosphere, the path loss, absorption attenuation, and selective fading experienced by different frequency components vary, resulting in severe distortion of the received signal spectrum. This module precisely shapes its gain-frequency response curve through an internal passive LC network or active equalization circuit, making it exhibit a shape opposite to the channel loss characteristics; that is, it provides higher gain at frequencies with higher channel loss and lower gain at frequencies with lower loss.

[0042] Understandably, after this frequency-selective equalization gain processing, the energy of the entire frequency band of the output signal is balanced, effectively correcting the signal distortion caused by frequency-selective fading. Finally, the module outputs a gain signal with increased amplitude and flattened spectral characteristics to the second port P2.

[0043] Understandably, this processing not only significantly improves the signal quality of a single-stage receiver, but more importantly, it provides an ideal input with stable amplitude and pure spectrum for the signal to enter the next stage of the same circuit unit. This fundamentally solves the distortion accumulation problem caused by the cascading of traditional flat gain amplifiers, making long-distance, multi-hop relay communication possible.

[0044] Based on the above, this embodiment provides a feasible implementation method. Please refer to... Figure 2 , Figure 2 This is one of the circuit topologies of the cascaded shortwave receiver amplifier circuit provided in the embodiments of this application.

[0045] In this embodiment, the filtering module includes: a first capacitor C1 and a first inductor L1; the first end of the first capacitor C1 is connected to the first port P1, and the second end of the first capacitor C1 is connected to the first end of the first inductor L1, the input terminal of the amplification module 20 and the input terminal of the limiting module, respectively; the second end of the first inductor L1 is grounded.

[0046] Understandably, the core function of the first capacitor C1 is to block DC. Utilizing the characteristic of a capacitor to pass AC while blocking DC, it completely blocks the DC component in the signal path, ensuring that only pure AC radio frequency signals can pass through. The first inductor L1 and the first capacitor C1 together form a first-order LC high-pass filter. The first inductor L1 provides a low-impedance path to ground for high-frequency signals, thereby effectively attenuating low-frequency interference components in the input signal and further purifying the signal.

[0047] In this embodiment, the limiting module includes: a first diode D1 and a second diode D2; the second terminal of the first capacitor C1 is connected to the cathode of the first diode D1 and the anode of the second diode D2 respectively; the anode of the first diode D1 and the cathode of the second diode D2 are both grounded.

[0048] It is understandable that the two back-to-back small signal radio frequency diodes D1 and D2 form a limiting circuit. Under normal operating conditions, it does not affect the passage of shortwave small signals. However, once the signal amplitude exceeds the diode's forward voltage, the signal will be directly short-circuited to the reference ground, thus protecting the subsequent circuits.

[0049] In this embodiment, the amplification module 20 includes: a second capacitor C2, an amplification chip U1, a third capacitor C3, a first resistor R1, a first filter capacitor C11, a second filter capacitor C12, and an RF choke ring RFC; the first end of the second capacitor C2 is connected to the output end of the filter module; the second end of the second capacitor C2 is connected to the input end of the amplification chip U1; the output end of the amplification chip U1 is connected to the first end of the third capacitor C3; the second end of the third capacitor C3 is connected to the input end of the equalization gain module 30; the power supply end of the amplification chip U1 is connected to the first end of the first filter capacitor C11 and the first end of the second filter capacitor C12 respectively; the first end of the first filter capacitor C11 and the first end of the second filter capacitor C12 are also grounded; the second end of the first filter capacitor C11 and the second end of the second filter capacitor C12 are connected to the first end of the first resistor R1 and the first end of the RF choke ring RFC respectively; the second end of the first resistor R1 is connected to the power supply; the second end of the RF choke ring RFC is connected to the output end of the amplification chip U1.

[0050] Understandably, the second capacitor C2, acting as an input DC blocking capacitor, ensures that the DC operating points of the filter module and the amplifier chip U1 are independent, preventing mutual interference, while allowing the RF signal to pass through without loss. The amplifier chip U1 is the core of the entire module, responsible for power gain of the clean RF signal. The amplifier chip U1 can be implemented using a broadband MMIC amplifier chip, requiring only a few external components to amplify shortwave signals. The third capacitor C3, acting as an output DC blocking capacitor, functions similarly to the second capacitor C2, blocking the DC component at the output of the amplifier chip U1 from entering the subsequent circuitry, ensuring that only AC RF signals are transmitted.

[0051] Understandably, providing a clean and stable operating voltage for the amplifier chip U1 is crucial. The first terminal of the RF choke RFC is connected to the power supply VCC through the first resistor R1. The RF choke RFC is implemented using a high-impedance inductor, presenting low impedance to DC signals, allowing DC current to pass smoothly; however, it presents high impedance to high-frequency RF signals, thus effectively preventing leakage loss of the amplified output RF signal through the power path. The first resistor R1 here serves to limit current and decouple, further stabilizing the power supply.

[0052] Understandably, the power supply connects to the first filter capacitor C11 and the second filter capacitor C12, both of which are grounded. These two capacitors, typically with different capacitance values, form a power supply decoupling network. They provide a low-impedance path to ground for noise of various frequencies on the power line, thereby providing a clean DC operating voltage for the amplifier chip U1 and preventing interference introduced through the power line from degrading circuit performance.

[0053] In this embodiment, the equalization gain module 30 includes: a second resistor R2, a third resistor R3, a fourth resistor R4, a fourth capacitor C4, a second inductor L2, and a fifth capacitor C5; the first end of the second resistor R2 is connected to the output terminal of the amplification module 20 and the first end of the fourth capacitor C4; the second end of the second resistor R2 is connected to the first end of the third resistor R3 and the first end of the fourth resistor R4; the second end of the third resistor R3 is connected to the first end of the second inductor L2; the second end of the second inductor L2 is grounded; the second end of the fourth resistor R4 is connected to the second end of the fourth capacitor C4 and the first end of the fifth capacitor C5; the second end of the fifth capacitor C5 is connected to the second port P2.

[0054] Understandably, the second resistor R2, the fourth resistor R4, and the third resistor R3 constitute a T-type attenuation circuit, providing a fixed, frequency-independent base attenuation. This serves as the reference for the entire equalization gain module 30. The fourth capacitor C4 and the second inductor L2 are used to adjust the transmission characteristics of the attenuation circuit. Specifically, at low frequencies, the capacitive reactance of the fourth capacitor C4 is very large, while the inductive reactance of the second inductor L2 is very small. The signal mainly flows to ground through the third resistor R3 and the second inductor L2, forming a strong shunt, thus resulting in significant low-frequency attenuation. At high frequencies, the capacitive reactance of the fourth capacitor C4 decreases, providing a shortcut for high-frequency signals, allowing them to more easily bypass the attenuation path of the third resistor R3 and the second inductor L2 and flow directly to the output. Simultaneously, the inductive reactance of the second inductor L2 increases, weakening its shunt effect on high-frequency signals. Therefore, high-frequency attenuation decreases, and it may even generate a certain gain relative to low frequencies. Ultimately, this results in large attenuation in the low-frequency range and small attenuation in the high-frequency range, with the gain curve of the entire circuit complementing the line loss characteristics of the shortwave signal.

[0055] Understandably, the equalized signal is output to the second port P2 via the fifth capacitor C5. The fifth capacitor C5 also acts as an output DC blocking capacitor, preventing DC current within the module from affecting subsequent circuits. This module utilizes a combination of resistors, capacitors, and inductors to construct a passive equalization circuit, successfully compensating for the signal frequency response to counteract the inherent high-frequency attenuation characteristics of transmission cables.

[0056] In this embodiment, a filtering module is used to remove DC and interference from the previous stage signal, resulting in a clean radio frequency (RF) signal, providing a distortion-free signal foundation for subsequent amplification. The RF signal is then amplified by an amplification module, directly increasing the signal strength and overcoming the inherent attenuation in single-stage transmission. Furthermore, an equalization gain module is used to perform gain processing on the amplified signal to compensate for the transmission link loss characteristics. This ensures that the signal strength accurately matches the actual line loss, effectively solving the problem of deteriorated signal reliability caused by the inability of a fixed gain method to adapt to the cumulative loss of multiple series stages.

[0057] Compared with existing technologies, through the synergistic effect of the above modules, this solution not only achieves stable cascading of shortwave signals in long-distance transmission, but also significantly improves the reliability and transmission distance of the entire transmission system by dynamically compensating for accumulated losses.

[0058] Furthermore, based on the above embodiments, this application optimizes the power supply section. Please refer to... Figure 3 , Figure 3 This is the second structural block diagram of the cascaded shortwave receiving amplifier circuit provided in the embodiments of this application.

[0059] In one embodiment, the cascadeable shortwave receiving amplifier circuit further includes: a DC-DC splitter module 40; the input terminal of the DC-DC splitter module 40 is connected to the second port P2; the first output terminal of the DC-DC splitter module 40 is connected to the first port P1; both the first port P1 and the second port P2 are radio frequency DC signal composite ports.

[0060] It should be noted that the DC separation module 40 is used to extract the DC component in the mixed signal of the second port and generate a first DC voltage signal to be transmitted to the first port P1; the first port P1 is used to transmit the radio frequency DC signal composed of the first DC voltage signal and the previous stage signal to the filtering module 10; the filtering module 10 is used to receive the DC voltage signal for power supply, filter out the interference components and DC components of the radio frequency DC signal, generate and transmit the radio frequency signal to the amplification module 20.

[0061] Understandably, the core function of the DC-DC splitter module 40 is to combine and separate signals and DC power, enabling a single port to transmit both RF signals and DC power simultaneously. This allows multiple such cascaded circuits to be cascaded via coaxial cables without the need for separate power lines for each stage, greatly simplifying system wiring and structure.

[0062] In one embodiment, the cascadeable shortwave receiving amplifier circuit further includes: a power supply adjustment module 50; the input terminal of the power supply adjustment module 50 is connected to the second output terminal of the DC separation module 40, and the output terminal of the power supply adjustment module 50 is connected to the power supply terminal of the amplifier module 20.

[0063] It should be noted that the DC separation module 40 is used to extract the DC component from the mixed signal at the second port and generate a second DC voltage signal to the power supply terminal of the amplifier module 20 to provide DC bias.

[0064] It should be noted that the power supply regulation module 50 converts the second DC voltage signal obtained from the separation module 40 into the operating voltage of the amplification module 20. On the one hand, this isolates the power supply of the amplification module 20 from the input power supply, preventing external power supply noise from being introduced; on the other hand, it allows for a wide input voltage range, providing a stable power supply voltage to the amplification module 20 when the external input voltage changes, thereby eliminating the impact of input voltage fluctuations on the operating state of the amplification circuit.

[0065] Specifically, please refer to Figure 4 , Figure 4 This is the second circuit topology diagram of the cascaded shortwave receiving amplifier circuit provided in the embodiments of this application.

[0066] In one embodiment, the DC separation module 40 includes: a third inductor L3, a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, a seventh inductor L7, an eighth inductor L8, a sixth capacitor C6, and a seventh capacitor C7; the third inductor L3, the fourth inductor L4, the fifth inductor L5, the sixth inductor L6, the seventh inductor L7, and the eighth inductor L8 are connected in series, with the first end of the series connection connected to the second port P2; the last end of the series connection is connected to the first port P1; the series terminals of the fifth inductor L5 and the sixth inductor L6 are respectively connected to the first terminal of the sixth capacitor C6, the input terminal of the power supply regulation module 50, and the first terminal of the seventh capacitor C7; the second terminal of the sixth capacitor C6 is grounded; the second terminal of the seventh capacitor C7 is grounded.

[0067] Understandably, in order to isolate the shortwave signals at ports P1 and P2, a large inductor must be used to provide sufficient RF impedance. However, this design uses a series connection of multiple inductors, which can effectively solve the problems of low self-resonant frequency and high DC resistance of large inductors, thereby achieving the function of passing DC and blocking RF.

[0068] It is understandable that the DC separation module 40 is a perfectly symmetrical DC signal pass-through circuit with T1 as the intermediate node. The T1 node refers to the common node of the fifth inductor L5 and the sixth inductor L6. The sixth inductor L6, the seventh inductor L7, the eighth inductor L8 and the seventh capacitor C7 form a low-pass circuit to couple the DC signal from the T1 node to the first port P1. Similarly, the third inductor L3, the fourth inductor L4, the fifth inductor L5 and the sixth capacitor C6 correspond one-to-one with the aforementioned inductor capacitance values ​​to form a perfectly symmetrical low-pass circuit to extract the DC signal from the second port P2 to the T1 node.

[0069] Understandably, to prevent shortwave signal crosstalk to the separation module 40, in principle, only large inductors need to be used at the positions of the third inductor L3 and the eighth inductor L8 at both ends. However, large inductors have the problem of low resonant frequency, which is not conducive to the isolation of high-frequency signals, and large DC resistance, which increases DC loss. Therefore, the third inductor L3, the fourth inductor L4, the fifth inductor L5, the sixth inductor L6, the seventh inductor L7, and the eighth inductor L8 are connected in series to form a single large inductor, which can effectively solve the problem caused by using a single large inductor. In addition, if it is not necessary to power the front-end, for example, when the antenna is directly connected to the first port P1, the eighth inductor L8 can be disconnected.

[0070] Specifically, please refer to Figure 5 , Figure 5 This is a circuit topology diagram of the power supply regulation module provided in the embodiments of this application.

[0071] In one embodiment, the power supply regulation module 50 includes: a voltage regulator chip U2, a third filter capacitor C13, and an output capacitor C14; the input terminal of the voltage regulator chip U2 is connected to the second output terminal of the DC-DC separation module 40 and the first terminal of the third filter capacitor C13 respectively; the second terminal of the third filter capacitor C13 is grounded; the output terminal of the voltage regulator chip U2 is connected to the power supply terminal of the amplification module 20 and the first terminal of the output capacitor C14 respectively; the second terminal of the output capacitor C14 is grounded; the voltage regulator chip U2 is used to convert the input terminal voltage into a bias voltage as a power input to the amplification module 20.

[0072] It is understandable that the high input voltage VH obtained at node T1, i.e., the second DC voltage, is converted into a low voltage VL to provide a stable bias voltage for the amplification module 20. Its circuit schematic is shown below. Figure 5As shown. The input high voltage VH is obtained from the intermediate node T1 of the separation module 40, and is converted into the amplifier's bias low voltage VL by the low-noise linear regulator chip U1. The third filter capacitor C13 is used to filter out high-frequency interference in the input high voltage VH. The output capacitor C14 is a high-frequency tantalum capacitor, which can effectively improve the stability of the output voltage. The bypass capacitor C15 can significantly improve the output noise of the regulator chip U1.

[0073] In this embodiment, the shortwave signal and the DC power supply signal are combined and transmitted on the same coaxial cable. The DC power supply signal is uploaded through a separation module, which enables the relay-type multi-stage cascading of amplifier circuits, and can significantly improve the wired transmission distance of the shortwave received signal.

[0074] Furthermore, based on the above, this application also proposes an embodiment of a shortwave communication system.

[0075] In this embodiment, the shortwave communication system includes: an antenna and a plurality of cascaded shortwave receiving amplifier circuits; each cascaded shortwave receiving amplifier circuit is connected end-to-end through a cable of a preset length to form a transmission network; the input end of the transmission network is connected to the antenna.

[0076] Understandably, the system begins with a receiving antenna, and the signal then passes through various processing units. Each unit's filtering module first purifies the RF-DC composite signal from the preceding stage, separating a clean RF signal for subsequent processing and extracting the DC component to power itself. The amplification module then boosts the signal amplitude. Finally, the equalization gain module precisely compensates for the signal's frequency response, correcting high-frequency losses caused by the circuitry and components themselves. The processed RF signal is then recombined with the DC power supply from the following stage at the output and transmitted to the next stage via cable. This design cleverly achieves synchronous signal and power transmission, allowing for remote power supply to all nodes in the entire transmission chain from a single power source at either the beginning or end of the link. This greatly simplifies system wiring and is particularly suitable for field communication scenarios requiring long-distance, low-loss transmission of shortwave signals.

[0077] Compared with the prior art, the beneficial effects of the shortwave communication system provided in this application are the same as those of the cascaded shortwave receiving amplifier circuit provided in the above embodiments, and will not be repeated here.

[0078] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0079] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A short wave receiving amplification circuit which can be cascaded, characterized by, The short wave receiving amplification circuit capable of cascading transmission comprises: a first port, a filtering module, an amplification module, an equalization gain module and a second port; the first port is connected to the input end of the filtering module; the output end of the filtering module is further connected to the first input end of the amplification module; the output end of the amplification module is connected to the input end of the equalization gain module; and the output end of the equalization gain module is connected to the second port; the first port is used for receiving a signal of a previous stage and transmitting to the filtering module; the filtering module is used for filtering out direct current and interference components in the signal of the previous stage, generating and transmitting a radio frequency signal to the amplification module; and the amplification module is used for amplifying the radio frequency signal and transmitting to the equalization gain module. the equalization gain module is used for gain processing on the amplified radio frequency signal, generating a gain signal output to the second port to realize multi-stage cascading; and the gain processing is to provide a gain complementary to the loss characteristics of a current signal transmission link.

2. The short wave receiving amplifying circuit of claim 1, wherein the first and second short wave receiving amplifying circuits are connected in cascade. The short wave receiving amplification circuit capable of cascading transmission further comprises a direct current separation module. the input end of the direct current separation module is connected to the second port; and the first output end of the direct current separation module is connected to the first port. the first port and the second port are both radio frequency direct current signal composite ports; the direct current separation module is used for extracting direct current components in the gain signal and generating a first direct current voltage signal transmitted to the first port; the first port is used for transmitting a radio frequency direct current signal composed of the first direct current voltage signal and the signal of the previous stage to the filtering module; the filtering module is used for receiving a direct current voltage signal for power supply and filtering out interference components and direct current components of the radio frequency direct current signal to generate and transmit a radio frequency signal to the amplification module.

3. The short wave receiving amplifying circuit of claim 2, wherein the first and second short wave receiving amplifying circuits are connected in cascade. The short wave receiving amplification circuit capable of cascading transmission further comprises a power supply adjustment module. the input end of the power supply adjustment module is connected to the second output end of the direct current separation module; and the output end of the power supply adjustment module is connected to the power supply end of the amplification module; the direct current separation module is used for extracting direct current components in the gain signal and generating a second direct current voltage signal to the power supply end of the amplification module to provide a direct current bias.

4. The short wave receive amplification circuit of claim 1, wherein, The short wave receiving amplification circuit capable of cascading transmission further comprises a limiting amplitude module. the input end of the limiting amplitude module is connected to the output end of the filtering module; the limiting amplitude module is used for limiting the radio frequency signal flowing to the amplification module when the amplitude of the radio frequency signal output by the filtering module exceeds a preset amplitude.

5. The short wave receive amplification circuit of claim 1, wherein, The filtering module comprises a first capacitor and a first inductor; the first end of the first capacitor is connected to the first port; the second end of the first capacitor is respectively connected to the first end of the first inductor, the input end of the amplification module and the input end of the limiting amplitude module; and the second end of the first inductor is grounded. The limiting amplitude module comprises a first diode and a second diode. the second end of the first capacitor is respectively connected to the cathode of the first diode and the anode of the second diode; the anode of the first diode and the cathode of the second diode are both grounded.

6. The short wave receive amplification circuit of claim 1, wherein, The amplification module comprises a second capacitor, an amplification chip, a third capacitor, a first resistor, a first filter capacitor, a second filter capacitor and a radio frequency choke ring. The first end of the second capacitor is connected to the output end of the filter module; the second end of the second capacitor is connected to the input end of the amplification chip; the output end of the amplification chip is connected to the first end of the third capacitor; the second end of the third capacitor is connected to the input end of the equalization gain module; The power supply end of the amplification chip is connected to the first end of the first filter capacitor and the first end of the second filter capacitor respectively; the first end of the first filter capacitor and the first end of the second filter capacitor are also grounded; The second end of the first filter capacitor and the second end of the second filter capacitor are connected to the first end of the first resistor and the first end of the radio frequency choke ring respectively; the second end of the first resistor is connected to the power supply; the second end of the radio frequency choke ring is connected to the output end of the amplification chip.

7. The short wave receive amplification circuit of claim 1, wherein, The equalization gain module comprises a second resistor, a third resistor, a fourth resistor, a fourth capacitor, a second inductor and a fifth capacitor; The first end of the second resistor is connected to the output end of the amplification module and the first end of the fourth capacitor respectively; the second end of the second resistor is connected to the first end of the third resistor and the first end of the fourth resistor respectively; the second end of the third resistor is connected to the first end of the second inductor; the second end of the second inductor is grounded; the second end of the fourth resistor is connected to the second end of the fourth capacitor and the first end of the fifth capacitor respectively; the second end of the fifth capacitor is connected to the second port.

8. The short wave receive amplification circuit of claim 3, wherein, The direct current separation module comprises a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, a seventh inductor, an eighth inductor, a sixth capacitor and a seventh capacitor; The third inductor, the fourth inductor, the fifth inductor, the sixth inductor, the seventh inductor and the eighth inductor are connected in series, and the first end of the series connection is connected to the second port; the last end of the series connection is connected to the first port; The series connection end of the fifth inductor and the sixth inductor is connected to the first end of the sixth capacitor, the input end of the power supply adjustment module and the first end of the seventh capacitor respectively; The second end of the sixth capacitor is grounded; the second end of the seventh capacitor is grounded.

9. The short wave receive amplification circuit of claim 3, wherein, The power supply adjustment module comprises a voltage stabilizing chip, a third filter capacitor and an output capacitor; The input end of the voltage stabilizing chip is connected to the second output end of the direct current separation module and the first end of the third filter capacitor respectively; the second end of the third filter capacitor is grounded; The output end of the voltage stabilizing chip is connected to the power supply end of the amplification module and the first end of the output capacitor respectively; the second end of the output capacitor is grounded; The voltage stabilizing chip is used to convert the input end voltage into a bias voltage as a power supply input to the amplification module.

10. A short wave communication system, characterized by The short wave communication system comprises an antenna and a plurality of short wave receiving amplification circuits capable of cascaded transmission as claimed in any one of claims 1 to 9; Each short wave receiving amplification circuit capable of cascaded transmission is connected in series through a cable of a preset length to form a transmission network; the input end of the transmission network is connected to the antenna.

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