Low-harmonic low-frequency tuning matching transmitting system and signal transmitting method thereof

Abstract

The invention belongs to the technical field of communication, and particularly discloses a low-harmonic low-frequency tuning matching transmitting system and a signal transmitting method thereof. The system comprises a cascade power amplification circuit and a tuning filtering matching circuit which are connected in sequence, the cascade power amplification circuit is used for processing the excitation signal into multiple paths of level driving signals and performing power amplification and synthesis on each path of level driving signal to generate a low-frequency signal with the power not smaller than target power; and the tuning filtering matching circuit is used for tuning and filtering the low-frequency signal, and adjusting the output impedance of the system and the input impedance of the antenna to reach an impedance matching state, so that the filtered low-frequency signal is transmitted in the impedance matching state. According to the invention, the harmonic content of the low-frequency signal can be effectively reduced, the low-frequency emission harmonic suppression performance of the maneuvering station is higher than the existing harmonic index, and the harmonic index of the maneuvering low-frequency communication system is effectively improved.

Description

Technical Field

[0001] The present application belongs to the field of communication technology, and more specifically, relates to a low-harmonic low-frequency tuning and matching transmission system and a signal transmission method thereof. Background Art

[0002] In the prior art, low-frequency communication systems are mainly divided into two categories: fixed and mobile. Fixed low-frequency communication systems mainly include shore-based fixed stations, and mobile low-frequency communication systems include two types of mobile stations: vehicle-mounted stations and airborne stations.

[0003] Compared with shore-based fixed stations, mobile stations have the following unique advantages: First, they are more maneuverable. They usually use transport vehicles as platforms, have long maneuvering distances, can be quickly transferred, and are accompanied by support and flexible to use. Second, the mission system is more integrated. They are generally supported by large vehicles, and the mission system is small in size, light in weight, and well integrated. Third, the communication antenna has a higher radiation efficiency. The radiation efficiency of the tower antenna of the shore-based fixed station is currently about 10-40%, and the radiation efficiency of the balloon antenna of the vehicle-mounted station is about 40-50%. Under the same radiation power, the communication distance of mobile stations such as vehicle-mounted stations is farther.

[0004] Due to the small space and high system integration of the mobile station, it has extremely high requirements for electromagnetic compatibility of low-frequency transmission. However, in practical applications, the highest harmonic index that can be achieved by the existing ground-based low-frequency transmission system is -50dB, which is difficult to meet the high electromagnetic compatibility performance requirements of low-frequency transmission under high integration, and it is easy to bring safety hazards to the mobile station equipment. Therefore, how to improve the harmonic index of the mobile low-frequency communication system has become a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present application is to improve the harmonic index of the mobile low-frequency communication system.

[0006] To achieve the above-mentioned purpose, the present application provides a low-harmonic low-frequency tuning and matching transmission system, comprising: a cascade power amplifier circuit and a tuning filter matching circuit connected in sequence;

[0007] The cascade power amplifier circuit is used to process the excitation signal into multiple level drive signals, and perform power amplification and synthesis on each level drive signal to generate a low-frequency signal with a power not less than the target power;

[0008] The tuning filter matching circuit is used to tune and filter the low-frequency signal, and adjust the output impedance of the system and the input impedance of the antenna to reach an impedance matching state, so that the low-frequency signal after filtering is transmitted under the impedance matching state.

[0009] Optionally, the cascade power amplifier circuit includes a power amplifier unit controller, a multi-channel power amplifier module and a power synthesis unit; the multi-channel output end of the power amplifier unit controller is connected to the input end of the multi-channel power amplifier module in a one-to-one correspondence, and the output end of the multi-channel power amplifier module is connected to the power synthesis unit;

[0010] The power amplifier unit controller is used to convert the excitation signal into a plurality of phase-shifted pulse signals, and generate a plurality of level driving signals based on the plurality of phase-shifted pulse signals, and output the plurality of level driving signals to the plurality of power amplifier modules; one level driving signal is correspondingly transmitted to one power amplifier module;

[0011] Each of the power amplifier modules is used to amplify the input level driving signal, and output the power-amplified level driving signal to the power synthesis unit;

[0012] The power synthesis unit is used to perform voltage sensing and signal synthesis on the power-amplified level driving signals of each channel, and output the low-frequency signal.

[0013] Optionally, the power amplifier unit controller includes a signal receiving conversion circuit, a signal processing circuit and an excitation output driving circuit connected in sequence;

[0014] The signal receiving and converting circuit is used to convert the received excitation signal into a digital signal, and input the digital signal into the signal processing circuit;

[0015] The signal processing circuit is used to detect the frequency information of the digital signal, and according to the frequency information, convert the digital signal into a plurality of phase-shifted pulse signals and transmit them to the excitation output drive circuit;

[0016] The excitation output driving circuit is used to perform signal isolation and signal amplification processing on each channel of the phase-shift pulse signal, and output multiple channels of the level driving signals.

[0017] Optionally, the power amplifier unit controller further includes a signal detection protection circuit;

[0018] The signal detection protection circuit is connected between the signal receiving conversion circuit and the signal processing circuit, and is used to receive the digital signal, generate a protection signal corresponding to the digital signal, and transmit the protection signal to the signal processing circuit; the protection signal is used to indicate an abnormal state of the digital signal;

[0019] The signal processing circuit is used to detect the protection signal, and when confirming that there is no abnormality in the digital signal, convert the digital signal into a multi-channel phase-shifted pulse signal according to the frequency information of the digital signal and output it to the excitation output drive circuit.

[0020] Optionally, the power synthesis unit includes a plurality of transformers, the primary coil of each transformer is correspondingly connected to one power amplifier module, and the secondary coils of the transformers are connected in series in sequence.

[0021] Optionally, the tuning filter matching circuit comprises a tuning subcircuit, a filtering subcircuit and a matching subcircuit connected in sequence; the tuning subcircuit, the filtering subcircuit and the matching subcircuit are all constructed based on inductance and capacitance;

[0022] The tuning subcircuit is used to adjust the low-frequency signal output by the cascade power amplifier circuit to a low-frequency signal of a target frequency; the target frequency is consistent with the design frequency of the antenna;

[0023] The filtering subcircuit is used to filter the low-frequency signal of the target frequency and output the low-frequency signal after filtering;

[0024] The matching subcircuit is used to adjust the output impedance of the system so that the output impedance reaches an impedance matching state with the input impedance of the antenna, and the low-frequency signal after filtering is transmitted under the impedance matching state.

[0025] Optionally, the tuning subcircuit includes an adjustable inductor L1 and a capacitor C1, the filtering subcircuit includes an inductor L2 and a capacitor C2, and the matching subcircuit includes an adjustable inductor L3 and a variable capacitor C3;

[0026] One end of the adjustable inductor L1 is connected to the first output end of the cascade power amplifier circuit, the other end of the adjustable inductor L1 is connected to one end of the capacitor C1, and the other end of the capacitor C1, one end of the inductor L2 and one end of the capacitor C2 are connected in common;

[0027] The other end of the inductor L2, one end of the adjustable inductor L3 and one end of the variable capacitor C3 are connected in common, and the other end of the capacitor C2, the other end of the adjustable inductor L3, the other end of the variable capacitor C3 and the second output end of the cascade power amplifier circuit are connected in common.

[0028] The present application provides a signal transmission method applied to any of the above-mentioned low-harmonic low-frequency tuning and matching transmission systems, comprising:

[0029] Processing the excitation signal into multiple level drive signals, and amplifying and synthesizing the power of each level drive signal to generate a low-frequency signal with a power not less than the target power;

[0030] The low-frequency signal is tuned and filtered, and the output impedance of the system and the input impedance of the antenna are adjusted to reach an impedance matching state, so that the low-frequency signal after filtering is transmitted in the impedance matching state.

[0031] Optionally, the cascade power amplifier circuit includes a power amplifier unit controller, a multi-channel power amplifier module and a power synthesis unit; the multi-channel output terminals of the power amplifier unit controller are connected to the input terminals of the multi-channel power amplifier modules in a one-to-one correspondence, and the output terminals of the multi-channel power amplifier modules are connected to the power synthesis unit; the excitation signal is processed into a multi-channel level driving signal, and the power of each channel of the level driving signal is amplified and synthesized to generate a low-frequency signal with a power not less than the target power, including:

[0032] Converting the excitation signal into a plurality of phase-shifted pulse signals, and generating a plurality of level driving signals based on the plurality of phase-shifted pulse signals;

[0033] Power amplification is performed on each of the level driving signals, and voltage sensing and signal synthesis are performed on each of the power-amplified level driving signals to output the low-frequency signal.

[0034] Optionally, the power amplifier unit controller includes a signal receiving conversion circuit, a signal processing circuit and an excitation output driving circuit connected in sequence; the excitation signal is converted into a plurality of phase-shifted pulse signals, and a plurality of level driving signals are generated based on the plurality of phase-shifted pulse signals, including:

[0035] Converting the received excitation signal into a digital signal, detecting the frequency information of the digital signal, and converting the digital signal into a multi-channel phase-shifted pulse signal according to the frequency information;

[0036] Perform signal isolation and signal amplification processing on each phase-shift pulse signal, and output multiple levels

[0037] In general, the above technical solutions conceived by the present application have at least the following beneficial effects compared with the prior art:

[0038] The present application provides a low-harmonic low-frequency tuning and matching transmission system and a signal transmission method thereof. The system includes a cascade power amplifier circuit and a tuning filter matching circuit connected in sequence. The cascade power amplifier circuit processes the excitation signal into a multi-channel level driving signal, and performs power amplification and synthesis on each channel of the level driving signal. The multi-level cascade power amplification method is used to suppress the harmonics output by the transmitter from the power amplification source, synthesize and output a high-power low-frequency signal, realize impedance transformation, electrical isolation and multi-level step wave output, and can effectively reduce the harmonic content of the low-frequency signal; and the tuning filter matching circuit is used to perform integrated processing of tuning, filtering and matching on the low-frequency signal, further suppressing the high-order harmonics of the transmitted low-frequency signal, so that the harmonic suppression performance of the low-frequency transmission of the mobile station can be higher than the existing harmonic index, effectively improving the harmonic index of the mobile low-frequency communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of a low harmonic low frequency tuning and matching transmission system provided in an embodiment of the present application;

[0040] Figure 2 It is a structural schematic diagram of a cascade power amplifier circuit in a low harmonic low-frequency tuning and matching transmission system provided in an embodiment of the present application;

[0041] Figure 3 It is a structural schematic diagram of a power amplifier unit controller in a cascade power amplifier circuit provided in an embodiment of the present application;

[0042] Figure 4 It is a schematic diagram of the principle of signal processing performed by a signal processing circuit in a power amplifier unit controller provided in an embodiment of the present application;

[0043] Figure 5 This is one of the structural schematic diagrams of a tuned filter matching circuit in a low harmonic low frequency tuned matching transmission system provided in an embodiment of the present application;

[0044] Figure 6 This is the second structural schematic diagram of the tuning filter matching circuit in the low harmonic low frequency tuning matching transmission system provided in the embodiment of the present application;

[0045] Figure 7 It is a flowchart of the signal transmission method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0047] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0048] In the description of the embodiments of the present application, unless otherwise specified, "multi-channel" means two or more channels. For example, a multi-channel level drive signal refers to two or more level drive signals, etc.; a multi-channel phase-shifted pulse signal refers to two or more phase-shifted pulse signals, etc.

[0049] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0050] Figure 1 is a schematic diagram of the structure of the low harmonic low frequency tuning and matching transmission system provided in the embodiment of the present application, such as Figure 1 As shown, the system comprises: a cascade power amplifier circuit 1 and a tuning filter matching circuit 2 connected in sequence;

[0051] The cascade power amplifier circuit 1 is used to process the excitation signal into multiple level drive signals, and to amplify and synthesize the power of each level drive signal to generate a low-frequency signal with a power not less than the target power;

[0052] The tuning filter matching circuit 2 is used to tune and filter the low frequency signal, and adjust the output impedance of the system and the input impedance of the antenna to achieve an impedance matching state, so that the low frequency signal after filtering is transmitted in the impedance matching state.

[0053] Specifically, the excitation signal described in the embodiment of the present application refers to an excitation signal generated by an exciter built into the system, which serves as a signal source of a signal transmitted by the system.

[0054] The level driving signal described in the embodiment of the present application refers to a driving signal represented by a level value, and the driving signal is used to drive a synthesized high-power low-frequency signal.

[0055] It can be understood that the low-frequency signal refers to a signal with a frequency ranging from 30 KHz to 300 KHz.

[0056] The target power described in the embodiment of the present application is used to characterize high power, and its specific value range may be 50KW to 55KW.

[0057] In an embodiment of the present application, a low-harmonic low-frequency tuned matching transmission system is constructed by using a cascade power amplifier circuit and a tuned filter matching circuit connected in sequence. Among them, the excitation signal generated by the internal exciter can be processed by the cascade power amplifier circuit and split into multiple level drive signals. The pre-designed power amplifier circuit, transformer network or impedance matching network can be used to perform power amplification and synthesis on each level drive signal by a multi-level power synthesis cascade method to achieve impedance transformation, electrical isolation and multi-level step wave output, and finally generate a low-frequency signal with a power not less than the target power. For example, the low-frequency signal of the target power can be a low-frequency signal with a power of 55KW. In this way, the harmonics output by the power amplifier can be effectively reduced while reducing signal reflection and energy loss and preventing mutual interference between circuits.

[0058] Furthermore, in the embodiments of the present application, taking into account the characteristics of the small space and high system integration of the mobile station, a tuning, filtering and matching integrated circuit is adopted, which integrates the three functions of tuning, filtering and matching. Specifically, the high-power low-frequency signal generated above can be tuned so that the frequency of the low-frequency signal output by the cascade power amplifier circuit is consistent with the transmitting antenna to achieve complete resonance; further, through filtering processing, the spurious frequency components in the low-frequency signal are filtered out. These spurious signals may be noise or interference generated by the internal transmission system, or they may be interference signals from the external environment. This can improve the purity and quality of the transmitted signal and further suppress the higher harmonics of the transmitted low-frequency signal.

[0059] Finally, in the matching link, the output impedance of the entire system can be adjusted through a pre-designed LC network to achieve impedance matching with the input impedance of the antenna, so that the filtered low-frequency signal can be transmitted in an impedance matching state, thereby minimizing signal reflection and improving transmission efficiency.

[0060] The low-harmonic low-frequency tuned matching transmission system of the embodiment of the present application includes a cascade power amplifier circuit and a tuned filter matching circuit connected in sequence. The cascade power amplifier circuit processes the excitation signal into a multi-channel level drive signal, and the power amplification and synthesis of each channel level drive signal are performed. The multi-level cascade power amplification method is used to suppress the harmonics output by the transmitter from the power amplification source, synthesize and output a high-power low-frequency signal, realize impedance transformation, electrical isolation and multi-level step wave output, and can effectively reduce the harmonic content of the low-frequency signal; and the low-frequency signal is tuned, filtered and matched in an integrated manner through the tuned filter matching circuit, thereby further suppressing the high-order harmonics of the transmitted low-frequency signal, so that the harmonic suppression performance of the mobile station low-frequency transmission can be higher than the existing harmonic index, effectively improving the harmonic index of the mobile low-frequency communication system.

[0061] Figure 2is a structural diagram of a cascade power amplifier circuit in a low harmonic low frequency tuning and matching transmission system provided in an embodiment of the present application, such as Figure 2 As shown, the cascade power amplifier circuit 1 includes a power amplifier unit controller 11, a multi-channel power amplifier module 12 and a power synthesis unit 13; the multi-channel output end of the power amplifier unit controller 11 is connected to the input end of the multi-channel power amplifier module 12 in a one-to-one correspondence, and the output end of the multi-channel power amplifier module 12 is connected to the power synthesis unit 13;

[0062] The power amplifier unit controller 11 is used to convert the excitation signal into a multi-channel phase-shifted pulse signal, and generate a multi-channel level driving signal based on the multi-channel phase-shifted pulse signal, and output the multi-channel level driving signal to the multi-channel power amplifier module 12; one channel level driving signal is correspondingly transmitted to one channel power amplifier module;

[0063] Each power amplifier module 12 is used to amplify the input level driving signal and output the power-amplified level driving signal to the power synthesis unit;

[0064] The power synthesis unit 13 is used to perform voltage sensing and signal synthesis on the power-amplified level driving signals of each channel, and output a low-frequency signal.

[0065] Specifically, in an embodiment of the present application, the cascade power amplifier circuit can be composed of three parts: a power amplifier unit controller, a multi-channel power amplifier module (n channels) and a power synthesis unit. Wherein, n≥2. The multi-channel output end of the power amplifier unit controller is connected to the input end of the multi-channel power amplifier module in a one-to-one correspondence. The power amplifier unit controller can convert the excitation signal into a multi-channel phase-shifted pulse signal by performing analog-to-digital conversion on the excitation signal. Wherein, the phase-shifted pulse signal is a pulse signal whose amplitude and period remain unchanged but whose phase is adjustable to a certain extent. Afterwards, the multi-channel phase-shifted pulse signal is processed into a multi-channel level drive signal through signal isolation and amplification means, and then each level drive signal is output to the corresponding power amplifier module for power amplification.

[0066] It should be noted that, in the embodiment of the present application, n power amplifier modules perform switching amplification on the excitation signal. Usually, the number of power amplifier modules can be set to be no less than 12 to ensure that the total amplified power is greater than 50 kW.

[0067] In an embodiment of the present application, the output end of the multi-channel power amplifier module is connected to the power synthesis unit. In this way, after power amplification processing, each power amplifier module further outputs the power-amplified level driving signal to the power synthesis unit for voltage sensing and signal synthesis.

[0068] Continue to refer to Figure 2Based on the contents of the above embodiments, as an optional embodiment, the power synthesis unit 13 includes a plurality of transformers 131, the primary coil of each transformer 131 is connected to a corresponding power amplifier module 12, and the secondary coils of each transformer 131 are connected in series in sequence.

[0069] Specifically, in an embodiment of the present application, the primary coil of each transformer in the power synthesis unit is connected to a power amplifier module, and the secondary coils of each transformer are connected in series in sequence to form a multi-transformer cascade circuit. In the multi-transformer cascade circuit, each transformer receives the level drive signal output by each power amplifier module. Here, the transformer mainly plays the role of voltage and current conversion, and may also include the functions of phase conversion and impedance matching. Through the cascading of transformers, the step-by-step amplification and conversion of the signal can be achieved to meet the requirements of the subsequent circuit.

[0070] In the embodiment of the present application, during the signal synthesis process, it is necessary to ensure that the phase relationship of each signal is consistent to achieve effective signal superposition. This can be achieved by adjusting the phase of each transformer so that the phase of all output signals remains consistent.

[0071] In the process of signal synthesis, in addition to the phase relationship, the amplitude of the signal also needs to be kept consistent. This can be achieved through amplitude control, amplitude balancing and other technical means to ensure that the amplitude contribution of each signal is equal during the synthesis process. After the phase and amplitude are adjusted, the signals will be vector superimposed, the power of each signal will be combined, and the final synthesized signal will be output to obtain a low-frequency signal with a power of not less than 50KW, realizing impedance transformation, electrical isolation and multi-level step wave output. Multi-level cascading can effectively reduce the harmonics output by the power amplifier, so that the 3rd, 5th, and 7th harmonic content is ≤-40dB.

[0072] It should be noted that in a multi-transformer cascade circuit, power matching is required between the n transformers and between the transformers and subsequent circuits to ensure efficient energy transmission and stable operation of the system.

[0073] In the embodiment of the present application, by adopting a power synthesis unit composed of a multi-transformer cascade circuit, synthesis and amplification of multiple signals can be achieved, which can effectively improve the power and quality of the output low-frequency signal.

[0074] The system of the embodiment of the present application constructs a cascade power amplifier circuit through a power amplifier unit controller, a multi-channel power amplifier module and a power synthesis unit, which can effectively process the excitation signal into a multi-channel level drive signal, and perform power amplification and synthesis, so as to suppress the transmitter output harmonics from the power amplification source by using a multi-level cascade power synthesis method, and can achieve low-frequency power amplification harmonics better than 40dB. While effectively suppressing the high-order harmonics of the transmitted low-frequency signal, it can also reduce the requirements for subsequent tuning and filtering circuits, which is beneficial to reducing the overall volume and weight of the system equipment.

[0075] Figure 3 is a schematic diagram of the structure of a power amplifier unit controller in a cascade power amplifier circuit provided in an embodiment of the present application, such as Figure 3 As shown, the power amplifier unit controller 11 includes a signal receiving conversion circuit 111, a signal processing circuit 112 and an excitation output driving circuit 113 connected in sequence;

[0076] The signal receiving conversion circuit 111 is used to convert the received excitation signal into a digital signal, and input the digital signal to the signal processing circuit 112;

[0077] The signal processing circuit 112 is used to detect the frequency information of the digital signal, and convert the digital signal into a multi-channel phase-shifted pulse signal according to the frequency information and transmit it to the excitation output driving circuit 113;

[0078] The excitation output driving circuit 113 is used to perform signal isolation and signal amplification processing on each phase-shift pulse signal, and output multiple level driving signals.

[0079] Specifically, in the embodiment of the present application, the power amplifier unit controller may be composed of a signal receiving conversion circuit, a signal processing circuit and an excitation output driving circuit connected in sequence. The signal receiving conversion circuit may be implemented by a filter circuit, an amplifier, a comparator, a digital logic circuit and other auxiliary circuits, and is responsible for receiving the analog signal output by the exciter, i.e., the excitation signal, and shaping the excitation signal to form a digital signal.

[0080] In an embodiment of the present application, the signal processing circuit can be implemented using a 4 million gate FPGA chip, which is used to collect the frequency information of the digitized excitation signal, and generate n phase-shifted pulse signals within one signal cycle based on the frequency information for subsequent output to n power amplifier modules.

[0081] Figure 4 is a schematic diagram showing the principle of signal processing performed by a signal processing circuit in a power amplifier unit controller provided in an embodiment of the present application, such as Figure 4As shown, it is a schematic diagram of a method for generating a 4-way phase-shifted pulse sequence when n is equal to 4; in an embodiment of the present application, the excitation signal is a sinusoidal signal, which is converted into a digital signal and then further processed through a signal processing circuit to obtain a 1# module waveform, a 2# module waveform, a 3# module waveform and a 4# module waveform, that is, to obtain 4-way phase-shifted pulse signals.

[0082] Among them, α1 to α4 represent the opening angles of the first power amplifier module to the fourth power amplifier module, and the specific calculation method is: α1 = arcsin (1 / 5), α2 = arcsin (2 / 5), α3 = arcsin (3 / 5), α4 = arcsin (4 / 5), where α1, α2, α3, α4∈(0, π / 2). After obtaining the angles from α1 to α4, it is easy to obtain the complete opening and closing control sequence waveforms of the four power amplifier modules, that is, 4 phase-shifted pulse signals. By analogy, when extended to the case of n power amplifier modules, α i =arcsin(i / n+1), where i∈(1,n), α i ∈(0,π / 2).

[0083] Furthermore, in an embodiment of the present application, after the signal processing circuit finally outputs n phase-shifted pulse signals, it transmits them to the excitation output driving circuit, which isolates and amplifies them to generate n level driving signals and sends them to n power amplifier modules.

[0084] In the embodiments of the present application, the excitation output driving circuit mainly realizes the isolation and amplification of the driving signal, and generally uses a high-speed isolation optical coupling device. Among them, the main purpose of the excitation output driving circuit for signal isolation is to eliminate the mutual interference between the input phase-shifted pulse signals of each channel, and to ensure the independence and accuracy of each signal. The purpose of the excitation output driving circuit for signal amplification is to enhance the amplitude of the signal so that it can drive the subsequent circuit system. Since the amplitude of the input signal may be small and cannot meet the driving requirements, it is necessary to enhance it through an amplification circuit. After completing the signal isolation and amplification, the processed signal needs to be distributed to n output channels to generate n-way level driving signals. This can usually be implemented using circuits such as a signal distributor or a switch matrix to convert a single-channel or multi-channel input signal into an n-channel output signal.

[0085] The system of the embodiment of the present application constructs a power amplifier unit controller by utilizing a signal receiving conversion circuit, a signal processing circuit and an excitation output driving circuit connected in sequence, which can efficiently convert the excitation signal into a multi-level driving signal, which is conducive to realizing multi-level cascade power synthesis and reducing the harmonics of the power amplifier output.

[0086] Continue to refer to Figure 3, based on the content of the above embodiment, as an optional embodiment, the power amplifier unit controller 11 further includes a signal detection protection circuit 114;

[0087] The signal detection protection circuit 114 is connected between the signal receiving conversion circuit 111 and the signal processing circuit 112, and is used to receive the digital signal, generate a protection signal corresponding to the digital signal, and transmit the protection signal to the signal processing circuit 112; the protection signal is used to indicate the abnormal state of the digital signal;

[0088] The signal processing circuit 112 is used to detect the protection signal, and when confirming that the digital signal is normal, convert the digital signal into a multi-channel phase-shifted pulse signal according to the frequency information of the digital signal and output it to the excitation output driving circuit 113.

[0089] Specifically, in an embodiment of the present application, a signal detection protection circuit may be introduced between the signal receiving conversion circuit and the signal processing circuit. After receiving the digital signal output by the signal receiving conversion circuit, the signal detection protection circuit generates a protection signal corresponding to the digital signal, and the protection signal may indicate an abnormal state of the digital signal.

[0090] Specifically, the signal detection protection circuit first receives the input digital signal and monitors these signals through the detection circuit. The detection circuit may include voltage detection, current detection, etc., to ensure the stability and normality of the signal. When an abnormality in the digital signal (such as overvoltage, overcurrent, undervoltage, etc.) is detected, the protection circuit will start immediately, such as timely locking the output pulse, protecting the signal, and realizing abnormal protection of the excitation signal. This usually includes cutting off abnormal signals, triggering alarms, or executing other predetermined protection measures to prevent signal damage or system failure. Based on the detection results, the protection circuit generates corresponding protection signals. These protection signals may exist in digital or analog form to indicate the current state or abnormality of the signal.

[0091] Furthermore, in an embodiment of the present application, the digital signal that has been protected and the protection signal are input into the signal processing circuit together. These signals will be further integrated and processed in the signal processing circuit. After detecting the protection signal, the signal processing circuit confirms that there is no abnormality in the digital signal. Then, in accordance with the aforementioned method, based on the frequency information of the digital signal, the digital signal is converted into a multi-channel phase-shifted pulse signal and output to the excitation output drive circuit for processing.

[0092] The system of the embodiment of the present application introduces a signal detection protection circuit between the signal receiving and conversion circuit and the signal processing circuit, utilizes means of detecting and protecting the input digital signal, ensures the stability and reliability of the signal, realizes the generation and detection protection of multi-level drive signals, and improves the quality of circuit transmission signals.

[0093] Figure 5 1 is one of the structural schematic diagrams of the tuning filter matching circuit in the low harmonic low frequency tuning matching transmission system provided in the embodiment of the present application, such as Figure 5 As shown, the tuning filter matching circuit 2 includes a tuning subcircuit 21, a filtering subcircuit 22 and a matching subcircuit 23 connected in sequence; the tuning subcircuit 21, the filtering subcircuit 22 and the matching subcircuit 23 are all constructed based on inductance and capacitance;

[0094] The tuning subcircuit 21 is used to adjust the low-frequency signal output by the cascade power amplifier circuit 1 to a low-frequency signal of a target frequency; the target frequency is consistent with the design frequency of the antenna;

[0095] The filter subcircuit 22 is used to filter the low-frequency signal of the target frequency and output the low-frequency signal after the filtering process;

[0096] The matching subcircuit 23 is used to adjust the output impedance of the system so that the output impedance reaches an impedance matching state with the input impedance of the antenna, and the low-frequency signal after filtering is transmitted in the impedance matching state.

[0097] Specifically, in the embodiment of the present application, the tuning filter matching circuit includes three parts, namely, a tuning subcircuit, a filtering subcircuit and a matching subcircuit, which are connected in sequence to realize an integrated circuit structure, wherein each subcircuit can be constructed based on inductance and capacitance elements.

[0098] In the transmission system of the present application, three subcircuits are used to perform tuning, filtering, and matching. Among them, through the tuning subcircuit, the size of the imaginary part of the impedance connected to the output end of the cascade power amplifier circuit can be adjusted to achieve complete resonance, so as to adjust the frequency of the transmission system to match the desired communication frequency, that is, the low-frequency signal output by the cascade power amplifier circuit is adjusted to the target frequency, which is consistent with the design frequency of the low-frequency antenna. In this way, the transmitted signal frequency can be ensured to be accurate. In addition, through the tuning link, other performance indicators of the transmission system, such as output power, phase noise, etc., can also be optimized to meet specific communication needs.

[0099] Furthermore, in an embodiment of the present application, the tuning link is followed by a filtering link. Through the filtering subcircuit, the main function is to further suppress the higher harmonics of the output current of the multi-level cascade power amplifier, and the suppression of harmonics reaches more than 40dB. Secondly, through filtering, the stray frequency components in the transmitted signal can also be removed. These stray signals may be noise or interference generated by the internal transmission system, or may be interference signals from the external environment; in addition, through filtering, the purity and quality of the transmitted signal can be improved, the interference to other communication systems can be reduced, and it can be ensured that the transmitted low-frequency signal can be accurately received by the opposite receiving end.

[0100] Furthermore, in an embodiment of the present application, the matching link follows the filtering link. In this link, the main purpose is to achieve impedance matching between the transmitting device (or circuit) and the low-frequency antenna through the matching subcircuit. By adjusting the parameters of the matching subcircuit network (such as LC network, etc.), the output impedance of the transmitting system and the input impedance of the low-frequency antenna are impedance matched, and the low-frequency signal after filtering is transmitted in an impedance matching state to minimize signal reflection and improve transmission efficiency. In addition, through the above-mentioned impedance matching, it is also possible to ensure that the power output by the transmitting system can be efficiently transmitted to the low-frequency antenna and radiated into space, which is crucial for long-distance communication and ensuring signal strength.

[0101] The system of the embodiment of the present application can further suppress high-order harmonics in the transmitted signal while ensuring the frequency accuracy and pure quality of the transmitted signal through integrated tuning, filtering, and matching three sub-circuit structures, and can be efficiently transmitted to the antenna and radiated out, thereby improving the harmonic index of the mobile low-frequency communication system.

[0102] Figure 6 FIG. 2 is a second structural diagram of a tuned filter matching circuit in a low harmonic low frequency tuned matching transmission system provided in an embodiment of the present application. Figure 6 As shown, the tuning subcircuit 21 includes an adjustable inductor L1 and a capacitor C1, the filtering subcircuit 22 includes an inductor L2 and a capacitor C2, and the matching subcircuit 23 includes an adjustable inductor L3 and a variable capacitor C3;

[0103] One end of the adjustable inductor L1 is connected to the first output end of the cascade power amplifier circuit, the other end of the adjustable inductor L1 is connected to one end of the capacitor C1, and the other end of the capacitor C1, one end of the inductor L2 and one end of the capacitor C2 are connected in common;

[0104] The other end of the inductor L2, one end of the adjustable inductor L3 and one end of the variable capacitor C3 are connected in common, and the other end of the capacitor C2, the other end of the adjustable inductor L3, the other end of the variable capacitor C3 and the second output end of the cascade power amplifier circuit are connected in common.

[0105] Specifically, in the embodiments of the present application, each sub-circuit in the tuned filter matching circuit is constructed by an inductor L and a capacitor C, so that the tuned filter matching circuit as a whole can achieve tuning and matching functions with a broadband low-frequency antenna by adjusting the adjustable inductor coils L1, L3 and the variable capacitor C3.

[0106] Among them, through the above description Figure 6The connection relationship between the inductor and capacitor components is that the tuning subcircuit forms a series low-Q tuning circuit through the adjustable inductor L1 and the capacitor C1; the filtering subcircuit forms a Γ-type low-pass filtering circuit by using the inductor L2 and the capacitor C2; the matching subcircuit forms a parallel impedance matching circuit through the adjustable inductor L3 and the variable capacitor C3.

[0107] In an embodiment of the present application, the adjustable inductor L1 can be adjusted through the tuning subcircuit to achieve the purpose of adjusting the size of the imaginary part of the impedance connected to the output end of the cascade power amplifier circuit and realize complete resonance, so that the cascade power amplifier circuit outputs a low-frequency signal of the target frequency.

[0108] In the embodiment of the present application, the adjustable inductor L3 and the variable capacitor C3 can be adjusted through the matching subcircuit so that the output impedance of the system and the input impedance of the antenna reach an impedance matching state.

[0109] More specifically, in the embodiment of the present application, the adjustment method of the adjustable parameters L1, L3 and C3 of the tuning filter matching circuit is as follows:

[0110] Step 1: Given the equivalent antenna impedance Zt, fixed capacitors C1, C2, fixed inductor L2, and characteristic impedance R of the cascade power amplifier circuit, Z3 is the impedance of the adjustable inductor L3 and the variable capacitor C3 in parallel, which is an unknown number, calculate the parallel impedance of Zt and Z3 so that the real part of the impedance is equal to the characteristic impedance R of the cascade power amplifier circuit, and the value of Z3 can be obtained. Among them, the electrical parameters of the given low-frequency broadband antenna are shown in Table 1.

[0111] Step 2: According to the value of Z3, the values ​​of the adjustable inductor L3 and the variable capacitor C3 can be determined. The adjustable inductor L3 and the variable capacitor C3 are both variables. The calculation principle is: take the maximum value within the range of the adjustable inductor L3, and calculate the value of the variable capacitor C3 at this time. At this time, the branch loss is the smallest.

[0112] Table 1

[0113] Frequency (kHz) Input resistance(Ω) Input reactance(Ω) efficiency(%) 30 2936.2 -4336.8 57.1 35 2651.1 -3175.4 67 40 2505.2 -2400 69.1 45 2270.8 -1832.6 70.8 50 2016.3 -1419.6 72.1 55 1782.9 -1111.6 73.3 60 1553.1 -896.6 74.2

[0114] Table 2

[0115]

[0116] Step 3, at this time, Z3 is a known number, calculate the impedance of Zt and Z3 in parallel, then connect it in series with L2, connect capacitor C2 in parallel to get Z2, connect Z2 in series with capacitor C1 and adjustable inductor L1 to get Z1, Z1 is a function of adjustable inductor L1, and solve the value of adjustable inductor L1 under the condition that the imaginary part of Z is 0. Among them, the data for calculating the adjustable parameters of the tuned filter matching circuit are shown in Table 2.

[0117] Thus, the values ​​of the adjustable parameters L1, L3 and C3 in the tuning, filtering and matching circuit can be determined, so as to perform the adjustment process of the three links of tuning, filtering and matching.

[0118] It should be noted that in the embodiment of the present application, the adjustable inductance coil adopts a design different from that of the ground station. The adjustable inductance coil is composed of a stator coil and a rotor coil. The maximum adjustment range of the inductance of the adjustable inductance coil is from 0.5mH to 3.3mH, which meets the requirements of a wide range of tuning circuits.

[0119] The design takes high voltage insulation into consideration. When the air insulation strength decreases (below 3kV / mm), high voltage easily causes air ionization and flashover. High temperature insulating thermal conductive epoxy resin vacuum potting is used to solve the problems of inter-turn discharge and ground insulation of the inductor coil. With the improvement of inter-turn insulation strength, the resin potting method can reduce the distance between coil turns, increase the number of coil turns, and realize the miniaturization of each unit inductance coil.

[0120] The system of the embodiment of the present application can achieve low-frequency power amplification harmonics better than 40dB through the design of various circuit structures and the use of a multi-level cascade power amplification method. The integrated tuning filter matching circuit can achieve harmonic suppression better than 40dB, thereby achieving total harmonic suppression better than 70dB, and achieving harmonic suppression of more than 70dB for the mobile low-frequency transmission system, which is 20dB higher than the harmonic index of the existing ground low-frequency transmission system, further effectively improving the performance indicators of the low-frequency communication system, and can meet the high electromagnetic compatibility performance requirements of low-frequency transmission under high integration.

[0121] Figure 7 is a flow chart of a signal transmission method provided in an embodiment of the present application, which method is applicable to any of the aforementioned low harmonic low frequency tuning matching transmission systems, such as Figure 7 As shown, the method includes:

[0122] Step S1, processing the excitation signal into multiple level drive signals, and performing power amplification and synthesis on each level drive signal to generate a low-frequency signal with a power not less than a target power;

[0123] Step S2, tuning and filtering the low-frequency signal, and adjusting the output impedance of the system and the input impedance of the antenna to reach an impedance matching state, so that the low-frequency signal after filtering is transmitted in the impedance matching state.

[0124] It should be understood that the method in the above embodiment is applied to the aforementioned low harmonic low-frequency tuning and matching transmission system, and its implementation principle and technical effect are similar to those described in the above system. The detailed process of the method can refer to the corresponding description process in the above system, and will not be repeated here.

[0125] The signal transmission method of the low-harmonic low-frequency tuning and matching transmission system of the embodiment of the present application processes the excitation signal into a multi-channel level driving signal through a cascade power amplifier circuit, and performs power amplification and synthesis on each channel of the level driving signal, and utilizes a multi-level cascade power amplification method to suppress the harmonics output by the transmitter from the power amplification source, synthesize and output a high-power low-frequency signal, realize impedance transformation, electrical isolation and multi-level step wave output, and can effectively reduce the harmonic content of the low-frequency signal; and tunes, filters and matches the low-frequency signal in an integrated manner through a tuning filter matching circuit, further suppresses the high-order harmonics of the transmitted low-frequency signal, and can make the harmonic suppression performance of the low-frequency transmission of the mobile station higher than the existing harmonic index, effectively improving the harmonic index of the mobile low-frequency communication system.

[0126] Based on the content of the above embodiment, as an optional embodiment, the cascade power amplifier circuit includes a power amplifier unit controller, a multi-channel power amplifier module and a power synthesis unit; the multi-channel output end of the power amplifier unit controller is connected to the input end of the multi-channel power amplifier module in a one-to-one correspondence, and the output end of the multi-channel power amplifier module is connected to the power synthesis unit; the excitation signal is processed into a multi-channel level driving signal, and the power of each level driving signal is amplified and synthesized to generate a low-frequency signal with a power not less than the target power, including:

[0127] Convert the excitation signal into a multi-channel phase-shift pulse signal, and generate a multi-channel level driving signal based on the multi-channel phase-shift pulse signal;

[0128] Power amplification is performed on each level driving signal, and voltage sensing and signal synthesis are performed on each power-amplified level driving signal to output a low-frequency signal.

[0129] Based on the content of the above embodiment, as an optional embodiment, the power amplifier unit controller includes a signal receiving conversion circuit, a signal processing circuit and an excitation output driving circuit connected in sequence; converting the excitation signal into a multi-channel phase-shifted pulse signal, and generating a multi-channel level driving signal based on the multi-channel phase-shifted pulse signal, including:

[0130] Convert the received excitation signal into a digital signal, detect the frequency information of the digital signal, and convert the digital signal into a multi-channel phase-shifted pulse signal according to the frequency information;

[0131] Perform signal isolation and signal amplification processing on each phase-shift pulse signal, and output multiple level drive signals.

[0132] Based on the content of the above embodiment, as an optional embodiment, the power amplifier unit controller further includes a signal detection protection circuit; the signal detection protection circuit is connected between the signal receiving conversion circuit and the signal processing circuit; after converting the received excitation signal into a digital signal, the method further includes:

[0133] Generate a protection signal corresponding to the digital signal, the protection signal is used to indicate an abnormal state of the digital signal;

[0134] Detect the protection signal, and when it is confirmed that there is no abnormality in the digital signal, convert the digital signal into a multi-channel phase-shifted pulse signal according to the frequency information of the digital signal.

[0135] Based on the content of the above embodiment, as an optional embodiment, the tuning filtering and matching circuit includes a tuning subcircuit, a filtering subcircuit and a matching subcircuit connected in sequence; the tuning subcircuit, the filtering subcircuit and the matching subcircuit are all constructed based on inductance and capacitance; the low-frequency signal is tuned and filtered, and the output impedance of the system is adjusted to reach an impedance matching state with the input impedance of the antenna, so that the low-frequency signal after filtering is transmitted in the impedance matching state, including:

[0136] The low-frequency signal output by the cascade power amplifier circuit is adjusted to be a low-frequency signal of a target frequency; the target frequency is consistent with the design frequency of the antenna;

[0137] Filtering the low-frequency signal of the target frequency and outputting the filtered low-frequency signal;

[0138] The output impedance of the system is adjusted so that the output impedance reaches an impedance matching state with the input impedance of the antenna, and the low-frequency signal after filtering is transmitted in the impedance matching state.

[0139] It should be understood that expressions such as "including" and "may include" that may be used in the present 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 the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0140] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0141] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A low harmonic low frequency tuning matching transmission system, characterized in that: include: A cascade power amplifier circuit and a tuned filter matching circuit connected in sequence; The cascade power amplifier circuit is used to process the excitation signal into multiple level drive signals, and perform power amplification and synthesis on each level drive signal to generate a low-frequency signal with a power not less than the target power; The tuning filter matching circuit is used to tune and filter the low-frequency signal, and adjust the output impedance of the system and the input impedance of the antenna to reach an impedance matching state, so that the low-frequency signal after filtering is transmitted under the impedance matching state.

2. The low harmonic low frequency tuning matching transmission system according to claim 1, characterized in that: The cascade power amplifier circuit comprises a power amplifier unit controller, a multi-channel power amplifier module and a power synthesis unit; the multi-channel output end of the power amplifier unit controller is connected to the input end of the multi-channel power amplifier module in a one-to-one correspondence, and the output end of the multi-channel power amplifier module is connected to the power synthesis unit; The power amplifier unit controller is used to convert the excitation signal into a plurality of phase-shifted pulse signals, generate a plurality of level driving signals based on the plurality of phase-shifted pulse signals, and output the plurality of level driving signals to the plurality of power amplifier modules; One channel of the level driving signal is correspondingly transmitted to one channel of the power amplifier module; Each of the power amplifier modules is used to amplify the input level driving signal, and output the power-amplified level driving signal to the power synthesis unit; The power synthesis unit is used to perform voltage sensing and signal synthesis on the power-amplified level driving signals of each channel, and output the low-frequency signal.

3. The low harmonic low frequency tuning matching transmission system according to claim 2, characterized in that: The power amplifier unit controller includes a signal receiving conversion circuit, a signal processing circuit and an excitation output driving circuit connected in sequence; The signal receiving and converting circuit is used to convert the received excitation signal into a digital signal, and input the digital signal into the signal processing circuit; The signal processing circuit is used to detect the frequency information of the digital signal, and according to the frequency information, convert the digital signal into a plurality of phase-shifted pulse signals and transmit them to the excitation output drive circuit; The excitation output driving circuit is used to perform signal isolation and signal amplification processing on each channel of the phase-shift pulse signal, and output multiple channels of the level driving signals.

4. The low harmonic low frequency tuning matching transmission system according to claim 3, characterized in that: The power amplifier unit controller also includes a signal detection protection circuit; The signal detection protection circuit is connected between the signal receiving conversion circuit and the signal processing circuit, and is used to receive the digital signal, generate a protection signal corresponding to the digital signal, and transmit the protection signal to the signal processing circuit; the protection signal is used to indicate an abnormal state of the digital signal; The signal processing circuit is used to detect the protection signal, and when confirming that there is no abnormality in the digital signal, convert the digital signal into a multi-channel phase-shifted pulse signal according to the frequency information of the digital signal and output it to the excitation output drive circuit.

5. The low harmonic low frequency tuning matching transmission system according to claim 2, characterized in that: The power synthesis unit includes a plurality of transformers, the primary coil of each transformer is connected to a corresponding power amplifier module, and the secondary coils of the transformers are connected in series in sequence.

6. The low harmonic low frequency tuning matching transmission system according to any one of claims 1 to 5, characterized in that: The tuned filtering and matching circuit comprises a tuning subcircuit, a filtering subcircuit and a matching subcircuit which are connected in sequence; the tuning subcircuit, the filtering subcircuit and the matching subcircuit are all constructed based on inductance and capacitance; The tuning subcircuit is used to adjust the low-frequency signal output by the cascade power amplifier circuit to a low-frequency signal of a target frequency; the target frequency is consistent with the design frequency of the antenna; The filtering subcircuit is used to filter the low-frequency signal of the target frequency and output the low-frequency signal after filtering; The matching subcircuit is used to adjust the output impedance of the system so that the output impedance reaches an impedance matching state with the input impedance of the antenna, and the low-frequency signal after filtering is transmitted under the impedance matching state.

7. The low harmonic low frequency tuning matching transmission system according to claim 6, characterized in that: The tuning subcircuit includes an adjustable inductor L1 and a capacitor C1, the filtering subcircuit includes an inductor L2 and a capacitor C2, and the matching subcircuit includes an adjustable inductor L3 and a variable capacitor C3; One end of the adjustable inductor L1 is connected to the first output end of the cascade power amplifier circuit, the other end of the adjustable inductor L1 is connected to one end of the capacitor C1, and the other end of the capacitor C1, one end of the inductor L2 and one end of the capacitor C2 are connected in common; The other end of the inductor L2, one end of the adjustable inductor L3 and one end of the variable capacitor C3 are connected in common, and the other end of the capacitor C2, the other end of the adjustable inductor L3, the other end of the variable capacitor C3 and the second output end of the cascade power amplifier circuit are connected in common.

8. A signal transmission method applied to the low harmonic low frequency tuning matching transmission system as described in any one of claims 1 to 7, characterized in that: include: Processing the excitation signal into multiple level drive signals, and amplifying and synthesizing the power of each level drive signal to generate a low-frequency signal with a power not less than the target power; The low-frequency signal is tuned and filtered, and the output impedance of the system and the input impedance of the antenna are adjusted to reach an impedance matching state, so that the low-frequency signal after filtering is transmitted in the impedance matching state.

9. The signal transmission method according to claim 8, characterized in that: The cascade power amplifier circuit includes a power amplifier unit controller, a multi-channel power amplifier module and a power synthesis unit; the multi-channel output end of the power amplifier unit controller is connected to the input end of the multi-channel power amplifier module in a one-to-one correspondence, and the output end of the multi-channel power amplifier module is connected to the power synthesis unit; the excitation signal is processed into a multi-channel level driving signal, and the power of each channel of the level driving signal is amplified and synthesized to generate a low-frequency signal with a power not less than the target power, including: Converting the excitation signal into a plurality of phase-shifted pulse signals, and generating a plurality of level driving signals based on the plurality of phase-shifted pulse signals; Power amplification is performed on each of the level driving signals, and voltage sensing and signal synthesis are performed on each of the power-amplified level driving signals to output the low-frequency signal.

10. The signal transmission method according to claim 9, characterized in that: The power amplifier unit controller includes a signal receiving conversion circuit, a signal processing circuit and an excitation output driving circuit connected in sequence; The step of converting the excitation signal into a plurality of phase-shifted pulse signals, and generating a plurality of level driving signals based on the plurality of phase-shifted pulse signals comprises: Converting the received excitation signal into a digital signal, detecting the frequency information of the digital signal, and converting the digital signal into a multi-channel phase-shifted pulse signal according to the frequency information; Signal isolation and signal amplification processing are performed on each channel of the phase-shift pulse signal, and multiple channels of the level driving signals are output.

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