Very low frequency transmitter and transmitting method

Abstract

The present application proposes a very low frequency transmitter and a transmission method, including: a digital exciter, used to perform continuous phase modulation (CPM) on a digital baseband signal to obtain a radio frequency signal and output it to a power amplifier, and based on the digital baseband signal and the CPM order, generate a synchronization control signal and output it to a dynamic tuning loop; a power amplifier, used to amplify the power of the radio frequency signal and output it to the dynamic tuning loop; a dynamic tuning loop, used to adjust the reactance parameters using the synchronization control signal and output the radio frequency signal to the antenna, so that the tuning point of the antenna feed system at the current moment is aligned with the frequency component of the signal being transmitted at the current moment. Since the dynamic tuning loop compensates the radio frequency signal in real time according to the synchronization control signal, the resonant frequency of the antenna changes dynamically with the change of the frequency component of the radio frequency signal, so that the circuit always resonates at different frequency components, and the time domain signals of different frequency components are output at the maximum, which is equivalent to expanding the antenna bandwidth.

Description

Technical Field

[0001] The present invention relates to the field of low frequency communication processing, and in particular to a very low frequency transmitter and a transmitting method. Background Art

[0002] Minimum Shift Keying (MSK) signal has been widely used in very low frequency communication because of its high frequency utilization and strong anti-noise performance.

[0003] The structural block diagram of the existing VLF communication transmitter is as follows: Figure 1 As shown in the figure, the transmission technology is to modulate the digital baseband signal using the MSK method, so that the very low frequency transmission antenna feed system resonates at the center frequency of the transmitter to offset the capacitive reactance of the antenna. This method makes the "transmission" and "space" frequencies of the MSK signal always in a detuned state. As the information rate of the MSK signal increases, the bandwidth occupied by the signal gradually increases. When it exceeds the bandwidth of the antenna feed system, the signal will be greatly attenuated and the information carried by the waveform will be lost. Therefore, the traditional very low frequency transmission technology has the problem of low signal transmission efficiency. Summary of the invention

[0004] In order to solve the problem of low transmission efficiency in the very low frequency signaling technology existing in the prior art, the present application provides a very low frequency transmitter and a signaling method.

[0005] A digital exciter is used to perform continuous phase modulation (CPM) on a digital baseband signal to obtain a radio frequency signal and output it to a power amplifier, and based on the digital baseband signal and the CPM modulation order, generate a synchronization control signal and output it to a dynamic tuning loop;

[0006] A power amplifier, used for amplifying the power of the radio frequency signal and outputting it to a dynamic tuning loop;

[0007] The dynamic tuning loop is used to adjust the reactance parameters of the dynamic tuning loop using a synchronous control signal, and output the power-amplified RF signal to the antenna, wherein the adjustment of the reactance parameters enables the tuning point of the antenna feed system to align with the frequency component of the RF signal being output at the current moment.

[0008] The digital exciter performs continuous phase modulation (CPM) on the digital baseband signal to obtain a radio frequency signal and outputs it to the power amplifier, and generates a synchronization control signal based on the digital baseband signal and the CPM order;

[0009] The power amplifier amplifies the power of the radio frequency signal and outputs it to the dynamic tuning loop;

[0010] The dynamic tuning loop uses a synchronous control signal to adjust the reactance parameters of the dynamic tuning loop and output the power-amplified RF signal to the antenna, wherein the adjustment of the reactance parameters makes the tuning point of the antenna feed system align with the frequency component of the RF signal being output at the current moment.

[0011] In the solution of the embodiment of the present application, since the dynamic tuning loop compensates the broadband RF signal after CPM modulation in real time according to the synchronization control signal, the resonant frequency of the antenna dynamically changes with the change of the frequency component of the modulated broadband RF signal. Since the entire circuit always resonates at different frequency components, the time domain signals of different frequency components can be output at the maximum, thereby equivalently expanding the antenna bandwidth of the transmitting system. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a block diagram of a transmitter in the background technology of this application;

[0013] Figure 2 This is one of the block diagrams of the transmitter in the embodiment of the present application;

[0014] Figure 3 This is the second block diagram of the transmitter system in the embodiment of the present application;

[0015] Figure 4 This is the third block diagram of the transmitter system in the embodiment of the present application;

[0016] Figure 5 A simplified structural diagram of a transmitter in an embodiment of the present application;

[0017] Figure 6 This is a flow chart of the signaling method of the signaling machine in the embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to solve the problem of low signal transmission efficiency in the existing very low frequency transmission technology, the embodiment of the present application proposes a very low frequency transmitter. On the one hand, a reactor is added in front of the network matching module in the prior art, and the newly added reactor and the existing network matching module together constitute a dynamic tuning module; on the other hand, a synchronous control signal generated by a digital baseband signal and a CPM modulation order is used in the exciter to control the dynamic tuning module, so that the resonant frequency of the antenna feed system changes dynamically with the change of the RF signal frequency. Since the entire dynamic tuning loop always resonates on different frequency components, the time domain signals of different frequency components can be output at the maximum, thereby equivalently expanding the antenna bandwidth of the transmitting system and improving the signal transmission efficiency.

[0019] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose, the present invention is described in detail below in conjunction with the accompanying drawings and preferred embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] Embodiment 1

[0021] like Figure 2 As shown, it is a structural block diagram of a very low frequency transmitter provided in an embodiment of the present application, including: a digital exciter 11, a power amplifier 12 and a dynamic tuning loop 13;

[0022] The digital exciter 11 is used to perform continuous phase modulation CPM on the digital baseband signal to obtain a radio frequency signal and output it to the power amplifier, and based on the digital baseband signal and the CPM modulation order, generate a synchronization control signal and output it to the dynamic tuning loop; the power amplifier 12 is used to amplify the power of the radio frequency signal and output it to the dynamic tuning loop;

[0023] The dynamic tuning circuit 13 is used to use the synchronous control signal to adjust the reactance parameters of the dynamic tuning circuit and output the power-amplified RF signal to the antenna, wherein the adjustment of the reactance parameters makes the tuning point of the antenna feed system align with the frequency component of the RF signal being output at the current moment, and the change of the reactance parameters can be inductive or capacitive, that is, in the tuning circuit, through this adjustment, the tuning circuit can always be in a resonant state when transmitting the RF signal.

[0024] Its working principle is as follows: the information source is the digital baseband signal to be transmitted (generally composed of binary), the digital exciter receives the digital baseband signal, performs CPM modulation on it, and generates a synchronous control signal based on the digital baseband signal and the CPM modulation order to obtain a modulated RF signal, which is sent to the power amplifier and the synchronous control signal is sent to the dynamic tuning loop. The synchronous control signal is used to control the dynamic tuning loop to compensate for the frequency components that exceed the bandwidth of the antenna system in real time. The dynamic tuning loop matches the RF signal with the antenna system in real time and radiates it through the antenna system.

[0025] In the scheme of the embodiment of the present application, instantaneous compensation is performed in the form of dynamic real-time variable reactance. This technology allows the resonant frequency of the antenna to change dynamically with the change of the transmitter excitation frequency. Since the dynamic tuning loop compensates the broadband RF signal after CPM modulation in real time according to the synchronization control signal, the resonant frequency of the antenna changes dynamically with the change of the frequency component of the modulated broadband RF signal. Since the entire circuit always resonates on different frequency components, the time domain signals of different frequency components can be output at maximum, thereby equivalently expanding the antenna bandwidth of the transmission system.

[0026] In a preferred solution, the digital exciter is specifically used to convert the data representing the digital baseband signal into M-base data, and generate synchronous control data according to the rule that the control line corresponding to the decimal number represented by each bit of the M-base data is in a control state, and the rest are in a non-control state, wherein M is the modulation order of the digital baseband signal, and the M-base data corresponds to M control lines (M=2, 4, 8, 16...).

[0027] The following describes the method of generating a synchronous control signal using the CPM order of 16 as an example:

[0028] Step 1: Convert the binary digital signal into M-ary data according to the M-order;

[0029] For example: The binary data 0000 0101 1010 1111, the order is 16, then when converted to hexadecimal, the data obtained is 05AF.

[0030] Step 2: Generate M control signals; initialize the states of the M control signals to 0 (0 means no control);

[0031] Continuing with the above example: generate 16 control signals, all initialized to 0.

[0032] Step 3: M-ary data, set the corresponding control signal state to 1 (1 means control);

[0033] Using the above example: the data is 05AF, there are 4 data to be sent, and the 1st control line, the 6th control line, the 11th control line, and the 16th control line are controlled in sequence to 1, and the other control lines are 0. The synchronous control signal at this time is 1000010000100001.

[0034] The digital baseband signal can control the reactance value of the reactor: For the tuning loop, the reactance value of the loop is divided into the inductive reactance of the tuning loop and the equivalent capacitive reactance of the antenna. When the inductive reactance value is equal to the capacitive reactance value, it is in a resonant state. Antenna capacitive reactance = 1 / wc, the inductive reactance value of the tuning loop is equal to wl, where w = 2πf, w is the angular frequency of the RF signal, f is the frequency of the RF signal, and l is the inductance value.

[0035] When the frequency of the transmitted signal changes, the loop will deviate from the original resonance point. Therefore, a digital baseband signal is needed to control the inductance value wl of the adjustable inductor of the tuning loop so that wl is always equal to 1 / wc.

[0036] Preferably, the dynamic tuning circuit includes: a reactor and a matching network. The block diagram of the transmitter is as follows: Figure 3 As shown;

[0037] The reactor is used to control the size of the reactance value by using a synchronous control signal to control the reactor unit to connect or disconnect the reactor unit from the dynamic tuning loop.

[0038] Better, such as Figure 4 As shown, the reactor includes: a transient reactance module driving main unit and N transient reactor units connected in series, wherein N is determined by comprehensive weighing based on the size of the RF signal, the specific reactance value to be compensated, the modulation order M, and the parameters of the solid-state switch in the transient reactor unit, and N is greater than or equal to M;

[0039] Assuming that the size of the RF signal is 100A, the specific reactance value to be compensated is 2 ohms, and the modulation order M is 4, the process of determining the number of transient reactor units N is as follows: The voltage tolerance of the transient reactor unit is restricted by the level of the device. For example, the current technical level can reach 1200V withstand voltage. When the RF signal size is 100A, a voltage of 200V will be generated on the 2-ohm reactor, and the peak-to-peak value is nearly 300V. Considering the possible voltage shock, a certain engineering margin is taken, and the rated working voltage is designed not to exceed 600V (peak-to-peak value), which can ensure the stable and reliable operation of the system. At this time, N can take the minimum value of M, and the number of N in the system is the least, and the system is the simplest. If the current to be transmitted in the loop is 200A, the reactance value to be compensated can be divided into two or more transient reactors, and N in the system can be equal to 6 or 8.

[0040] The transient reactance module driving main unit is used to transmit the synchronous control signal to each transient reactance unit through the bus;

[0041] The transient reactor unit is used to switch in or out of the dynamic tuning loop according to the control of the received synchronous control signal.

[0042] Preferably, each transient reactor unit comprises a radio frequency input port, a radio frequency output port and a fiber optic interface;

[0043] The transient reactance module driving main unit is used to transmit the synchronous control signal to each transient reactance unit through the optical fiber bus.

[0044] In addition, the present application also provides a simplified structural diagram of the transmitter, such as Figure 5 shown.

[0045] Based on the same inventive concept as the above embodiment, the present application also proposes a very low frequency signaling method, the flow chart of which is as follows: Figure 6 As shown, the following steps are included:

[0046] Step 601: The digital exciter performs continuous phase modulation (CPM) on the digital baseband signal to obtain a radio frequency signal and outputs it to the power amplifier, and generates a synchronization control signal based on the digital baseband signal and the CPM order;

[0047] Step 602: The power amplifier amplifies the power of the radio frequency signal and outputs it to the dynamic tuning loop;

[0048] Step 603: The dynamic tuning loop uses the synchronous control signal to adjust the reactance parameters of the dynamic tuning loop to output the power-amplified RF signal to the antenna, wherein the reactance parameters are adjusted so that the tuning point of the antenna feed system is aligned with the frequency component of the RF signal being output at the current moment.

[0049] Preferably, generating a synchronization control signal based on the digital baseband signal and the CPM order includes:

[0050] Converting the data representing the digital baseband signal into M-ary data;

[0051] Synchronous control data is generated according to the rule that the control line corresponding to the decimal number represented by each bit of the M-ary data is in a control state, and the rest are in a non-control state, where M is the modulation order of the digital baseband signal, and the M-ary data corresponds to M control lines.

[0052] Preferably, the dynamic tuning circuit includes: a reactor and a matching network;

[0053] The dynamic tuning circuit uses a synchronous control signal to adjust the reactance parameters of the dynamic tuning circuit, including:

[0054] The reactor receives the synchronous control signal and uses the synchronous control signal to control the magnitude of the reactance value by switching on or off the reactance unit.

[0055] Preferably, the reactor comprises: a transient reactance module driving main unit and N transient reactor units connected in series, wherein N is determined by comprehensive weighing of the size of the RF signal, the specific reactance value to be compensated, the modulation order M and the parameters of the solid-state switch in the transient reactor unit, and N is less than or equal to M;

[0056] The synchronous control signal is used to adjust the reactance parameters of the dynamic tuning loop, including:

[0057] The transient reactance module drives the main unit to transmit the synchronous control signal to each transient reactance unit through the bus;

[0058] The transient reactor unit is connected to or disconnected from the dynamic tuning loop according to the control of the received synchronous control signal.

[0059] Preferably, each transient reactor unit comprises a radio frequency input port, a radio frequency output port and a fiber optic interface;

[0060] The transient reactor module drives the main unit to transmit the synchronous control signal to each transient reactor unit through the bus, including:

[0061] The transient reactance module drives the main unit to transmit the synchronous control signal to each transient reactance unit through the optical fiber bus.

[0062] Through the description of the specific implementation methods, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the predetermined purpose should be obtained. However, the accompanying drawings are only for reference and illustration purposes and are not intended to limit the present invention.

Claims

1. A very low frequency transmitter, characterized in that: include: Digital exciters, power amplifiers and dynamic tuning loops; A digital exciter is used to perform continuous phase modulation (CPM) on a digital baseband signal to obtain a radio frequency signal and output it to a power amplifier, and based on the digital baseband signal and the CPM modulation order, generate a synchronization control signal and output it to a dynamic tuning loop; A power amplifier, used for amplifying the power of the radio frequency signal and outputting it to a dynamic tuning loop; A dynamic tuning loop, used to adjust the reactance parameters of the dynamic tuning loop by using a synchronous control signal, and output the power-amplified radio frequency signal to the antenna, wherein the adjustment of the reactance parameters makes the tuning point of the antenna feed system align with the frequency component of the radio frequency signal being output at the current moment; The digital exciter is specifically used to convert the data representing the digital baseband signal into M-base data, and generate synchronous control data according to the rule that the control line corresponding to the decimal number represented by each bit of the M-base data is in a control state, and the rest are in a non-control state, wherein M is the modulation order of the digital baseband signal, and the M-base data corresponds to M control lines.

2. The very low frequency transmitter according to claim 1, characterized in that: The dynamic tuning circuit includes: a reactor and a matching network; The reactor is used to control the size of the reactance value by using a synchronous control signal to control the reactor unit to connect or disconnect the reactor unit from the dynamic tuning loop.

3. The VLF transmitter according to claim 2, characterized in that: The reactor comprises: a transient reactance module driving main unit and N transient reactor units connected in series, wherein N is determined by comprehensive weighing based on the size of the radio frequency signal, the specific reactance value to be compensated, the modulation order M and the parameters of the solid-state switch in the transient reactor unit, and N is equal to M; The transient reactance module driving main unit is used to transmit the synchronous control signal to each transient reactance unit through the bus; The transient reactor unit is used to switch in or out of the dynamic tuning loop according to the control of the received synchronous control signal.

4. The VLF transmitter according to claim 3, characterized in that: Each transient reactor unit includes an RF input port, an RF output port, and an optical fiber interface; The transient reactance module driving main unit is used to transmit the synchronous control signal to each transient reactance unit through the optical fiber bus.

5. A very low frequency signaling method, characterized in that: include: The digital exciter performs continuous phase modulation (CPM) on the digital baseband signal to obtain a radio frequency signal and outputs it to the power amplifier, and generates a synchronization control signal based on the digital baseband signal and the CPM order; The power amplifier amplifies the power of the radio frequency signal and outputs it to the dynamic tuning loop; The dynamic tuning loop uses the synchronous control signal to adjust the reactance parameters of the dynamic tuning loop, and outputs the power-amplified RF signal to the antenna, wherein the adjustment of the reactance parameters makes the tuning point of the antenna feed system align with the frequency component of the RF signal being output at the current moment; Based on the digital baseband signal and the CPM order, a synchronization control signal is generated, including: Converting the data representing the digital baseband signal into M-ary data; Synchronous control data is generated according to the rule that the control line corresponding to the decimal number represented by each bit of the M-ary data is in a control state, and the rest are in a non-control state, where M is the modulation order of the digital baseband signal, and the M-ary data corresponds to M control lines.

6. The method according to claim 5, characterized in that The dynamic tuning circuit includes: a reactor and a matching network; The dynamic tuning circuit uses a synchronous control signal to adjust the reactance parameters of the dynamic tuning circuit, including: The reactor receives the synchronous control signal and uses the synchronous control signal to control the magnitude of the reactance value by switching on or off the reactance unit.

7. The method according to claim 6, characterized in that The reactor comprises: a transient reactance module driving main unit and N transient reactor units connected in series, wherein N is determined by comprehensive weighing based on the size of the radio frequency signal, the specific reactance value to be compensated, the modulation order M and the parameters of the solid-state switch in the transient reactor unit, and N is less than or equal to M; The synchronous control signal is used to adjust the reactance parameters of the dynamic tuning loop, including: The transient reactance module drives the main unit to transmit the synchronous control signal to each transient reactance unit through the bus; The transient reactor unit is connected to or disconnected from the dynamic tuning loop according to the control of the received synchronous control signal.

8. The method according to claim 7, characterized in that Each transient reactor unit includes an RF input port, an RF output port, and an optical fiber interface; The transient reactor module drives the main unit to transmit the synchronous control signal to each transient reactor unit through the bus, including: The transient reactance module drives the main unit to transmit the synchronous control signal to each transient reactance unit through the optical fiber bus.

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