A channel switching system and method for ground-based SAR

Abstract

The present application discloses a channel switching system and method for a ground-based SAR. The system includes a filtering module for filtering input radio frequency signals; a power splitter module including several signal output channels, the power splitter module being configured to, in response to control by an external signal, switch on one of the several signal output channels and output the filtered radio frequency signal through the switched-on signal output channel; and a signal processing module including several signal processing units, each of which is connected to a corresponding signal output channel of the power splitter module and is configured to receive the radio frequency signal output by the corresponding signal output channel and amplify or suppress the radio frequency signal. This can improve the isolation between the control channels of the ground-based SAR array transmitting antenna and increase the channel switching rate.

Description

Technical Field

[0001] The present application relates to the technical field of communication systems, and in particular to a channel switching system and method for ground-based SAR. Background Art

[0002] Ground-based SAR deformation detection radar is a technology widely used in the field of geological disaster detection. It can achieve non-contact and all-weather monitoring of terrain deformation over large areas and long distances, providing data support for disaster warning and decision-making. However, traditional ground-based SAR deformation detection radar uses a mechanical scanning method, which has the following problems: mechanical scanning leads to low data acquisition efficiency. At the same time, as the equipment is used, the aging of the track may introduce mechanical errors, affecting the accuracy of the data. To address these problems, existing deformation detection methods use array transmitting antennas to replace mechanical scanning, achieving data acquisition by changing the phase center. Although this method improves efficiency and accuracy to a certain extent, it still has some shortcomings, such as low isolation between channels and slow channel switching, and there is still much room for improvement in practical applications. Summary of the Invention

[0003] To this end, embodiments of the present application provide a channel switching system and method for a ground-based SAR, which improves the isolation between channels of an array transmitting antenna and increases the channel switching rate.

[0004] In a first aspect, the present application provides a channel switching system for a ground-based SAR.

[0005] This application is achieved through the following technical solutions:

[0006] A channel switching system for a ground-based SAR, comprising:

[0007] A filtering module, used for filtering the input radio frequency signal;

[0008] a power splitter module, comprising a plurality of signal output channels, wherein the power splitter module is configured to, in response to control of an external signal, turn on one of the plurality of signal output channels, so that the filtered radio frequency signal is output through the turned-on signal output channel;

[0009] The signal processing module includes several signal processing units, each of which is connected to a signal output channel of the power division module, and is used to receive the radio frequency signal output by the corresponding signal output channel and amplify or suppress the radio frequency signal.

[0010] In a preferred example of the present application, it can be further configured that the filtering module includes at least one of a bandpass filter, a low-pass filter or a high-pass filter.

[0011] In a preferred example of the present application, it can be further configured that the filtering module is a bandpass filter;

[0012] The bandpass filter is composed of a first phase shift unit and a second phase shift unit connected in series;

[0013] The first phase shift unit is used to form a first zero point position for the input radio frequency signal,

[0014] The second phase shift unit is used to form a second zero point position for the input radio frequency signal.

[0015] In a preferred example of the present application, it can be further configured that the first phase shifting unit includes a first pole, a second pole, and a third pole, the first pole and the second pole are coupled by an inductor, the first pole and the third pole are coupled by an inductor, and the second pole and the third pole are coupled by an inductor;

[0016] The second phase shift unit includes a fourth pole, a fifth pole and a sixth pole. The fourth pole and the fifth pole are coupled by an inductor, the fifth pole and the sixth pole are coupled by an inductor, and the fourth pole and the sixth pole are coupled by a capacitor.

[0017] In a preferred example of the present application, it can be further configured that the first pole, the second pole, the third pole, the fourth pole, the fifth pole and the sixth pole are all composed of parallel LC resonant circuits.

[0018] In a preferred example of the present application, it can be further configured that the power division module includes a signal input channel and a plurality of signal output channels;

[0019] The signal input channel is controlled by an external DC bias signal;

[0020] Each signal output channel includes a diode and a capacitor connected in series, wherein the anode of the diode is connected to the signal input channel, and the cathode of the diode is connected in series with the capacitor. The diode is configured to control the conduction or cutoff of the output channel in response to an external DC bias signal.

[0021] In a preferred example of the present application, it can be further configured that the signal processing unit includes a power amplifier and a switch control circuit, and the switch control circuit is used to control the opening and closing of the power amplifier.

[0022] In a preferred example of the present application, it can be further configured that the switch control circuit includes: an analog single-pole double-throw switch, a positive power supply current sensor, an analog-to-digital converter, and an integrated operational amplifier;

[0023] The output end of the single-pole double-throw switch is connected to the input end of the positive power supply current sensor, the first output end of the positive power supply current sensor is connected to the positive power supply input end of the power amplifier, the second output end of the positive power supply current sensor is connected to the input end of the analog-to-digital converter, the output end of the analog-to-digital converter is connected to the input end of the integrated operational amplifier, and the output end of the integrated operational amplifier is connected to the negative power supply input end of the power amplifier.

[0024] In a preferred example of the present application, it can be further configured that a closed-loop control unit is also included between the second output end of the positive power supply current sensor and the input end of the analog-to-digital converter, and the closed-loop control unit is configured to obtain the positive power supply current value of the positive power supply current sensor, use an improved PID algorithm to convert the positive power supply current value into a digital voltage, and transmit the digital voltage to the analog-to-digital converter.

[0025] In a preferred example of the present application, it can be further configured that the closed-loop control unit is configured as follows:

[0026] receiving a positive power supply current from a positive current sensor, and calculating a current error based on the positive power supply current and an expected current;

[0027] Perform proportional operation on the current error to obtain the proportional operation result;

[0028] Perform time-compensated integration on the current error to obtain the error integration result;

[0029] Perform time-compensated differential operation on the current error to obtain the error differential result;

[0030] Superimposing the proportional operation result, the error integral result, and the error differential result, and performing impulse operation on the superimposed result to obtain an impulse operation result;

[0031] A digital voltage is determined based on the impulse calculation result, and the digital voltage is output to an analog-to-digital converter.

[0032] In a second aspect, the present application provides a channel switching method for ground-based SAR.

[0033] The present application is achieved through the following technical solutions: A channel switching method for ground-based SAR, comprising:

[0034] The filtering module receives the RF signal from the signal source, filters the RF signal, and inputs the filtered RF signal to the power splitter module;

[0035] Under the control of an external signal, the power splitter module switches on one of the signal output channels, so that the filtered RF signal is output through the switched-on signal output channel.

[0036] The signal processing unit of the control signal processing module amplifies or suppresses the radio frequency signal output by the corresponding power division module, and transmits the processed radio frequency signal to the target antenna.

[0037] In a preferred example of the present application, it can be further configured that the filtering module is at least one of a bandpass filter, a low-pass filter or a high-pass filter.

[0038] In a preferred example of the present application, it can be further configured that the filtering module is a bandpass filter, and the bandpass filter is composed of a first phase shift unit and a second phase shift unit connected in series.

[0039] The filtering module receives the RF signal from the signal source and performs filtering on the RF signal, including:

[0040] A first zero point position is formed for the radio frequency signal by the first phase shift unit, and a second zero point position is formed for the radio frequency signal by the second phase shift unit.

[0041] In a preferred example of the present application, it can be further configured that the power division module includes a signal input channel and a plurality of signal output channels;

[0042] The signal input channel is controlled by an external DC bias signal;

[0043] Each signal output channel includes a diode and a capacitor connected in series, wherein the anode of the diode is connected to the signal input channel, and the cathode of the diode is connected in series with the capacitor. The diode is configured to control the conduction or cutoff of the output channel in response to an external DC bias signal.

[0044] In a preferred example of the present application, it can be further configured that each signal processing unit includes a power amplifier and a switch control circuit, and the signal processing unit of the control signal processing module amplifies or suppresses the radio frequency signal output by the corresponding power division module, and transmits the processed radio frequency signal to the target antenna, including:

[0045] The power amplifier, under the control of the switch control circuit, amplifies or suppresses the RF signal output by the power divider module and transmits the processed RF signal to the target antenna.

[0046] In summary, compared with the prior art, the technical solutions provided by the embodiments of the present application have at least the following beneficial effects:

[0047] The channel switching system of the present application includes a filtering module for filtering the input radio frequency signal; a power splitting module including several signal output channels, wherein the power splitting module is configured to, in response to the control of an external signal, conduct one of the several signal output channels and output the filtered radio frequency signal through the conducted signal output channel; and a signal processing module including several signal processing units, each of which is connected to a signal output channel of the power splitting module and is used to receive the radio frequency signal output by the corresponding signal output channel and amplify or suppress the radio frequency signal. Rapid switching between channels is achieved, channel coupling is reduced, and closed-loop control of the transmission power is achieved, thereby ensuring efficient monitoring of terrain and effective acquisition of deformation data by the ground-based SAR deformation detection radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic structural diagram of a channel switching system for a ground-based SAR according to an embodiment of the present application;

[0049] Figure 2 A schematic diagram of the structure of a filter module provided in one embodiment of the present application;

[0050] Figure 3 A schematic diagram of the structure of a power splitter module provided in one embodiment of the present application;

[0051] Figure 4 A schematic diagram of the structure of a signal processing module provided in one embodiment of the present application;

[0052] Figure 5 A schematic structural diagram of a signal processing module provided in yet another embodiment of the present application;

[0053] Figure 6 A schematic flow chart of an improved PID algorithm provided in another embodiment of the present application;

[0054] Figure 7 A schematic diagram of a flow chart of channel switching for a ground-based SAR according to another embodiment of the present application;

[0055] Description of reference numerals:

[0056] Filter module 10 , power division module 20 , signal processing module 30 . DETAILED DESCRIPTION

[0057] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

[0058] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0059] In addition, the term "and / or" in this application is simply a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application, unless otherwise specified, generally indicates that the related objects are in an "or" relationship.

[0060] In this application, the terms "first", "second", etc. are used to distinguish identical or similar items with substantially the same effects and functions. It should be understood that there is no logical or temporal dependency between "first", "second", and "nth", nor is there any limitation on the quantity and execution order.

[0061] In the embodiments of this 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 this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0062] The embodiments of the present application are described in further detail below with reference to the accompanying drawings.

[0063] like Figure 1 As shown, the first exemplary embodiment of the present application provides a channel switching system for a ground-based SAR, which includes: a filtering module 10, a power splitter module 20, and a signal processing module 30. The input end of the filtering module 10 is used to receive the radio frequency signal input from the radio frequency source into the channel switching system of the present application, the output end of the filtering module 10 is connected to the signal input channel of the power splitter module 20, the signal output channel of the power splitter module 20 is connected to the input end of the signal processing module 30, and the output end of the signal processing module 30 is connected to the array antenna.

[0064] Among them, the filtering module 10 is used to filter the input RF signal; the power division module 20 includes several signal output channels. The power division module 20 is configured to respond to the control of an external signal and turn on one of the several signal output channels so that the filtered RF signal is output through the turned-on signal output channel; the signal processing module 30 includes several signal processing units, each of which is connected to a signal output channel of the power division module and is used to receive the RF signal output by the corresponding signal output channel and amplify or suppress the RF signal. It should be noted that each signal output channel of the power division module 20 corresponds to a signal processing unit, and the output end of the signal processing unit corresponds to an antenna in the multi-channel array antenna, which is used to output the RF signal to the antenna. The array antenna is oriented toward the area where deformation detection is required (such as a hillside) and sends RF signals to the target detection area. The other array antennas set on the target detection area receive these RF signals and perform subsequent deformation detection analysis.

[0065] Understandably, each signal output channel may be turned on in sequence based on a preset time interval; or the target antenna that outputs the RF signal may turn on the corresponding signal output channel as needed.

[0066] The filtering module 10 includes at least one of a bandpass filter, a low-pass filter or a high-pass filter.

[0067] Preferably, the filtering module 10 of the present application adopts a bandpass filter of a cross-coupling model, and the bandpass filter is composed of a first phase shifting unit and a second phase shifting unit connected in series; the first phase shifting unit is used to form a first zero point position for the input RF signal, and the second phase shifting unit is used to form a second zero point position for the input RF signal.

[0068] The front-end equipment of the present invention, such as a radio frequency signal source, often produces radio frequency signals that are not required outside the passband, such as spurious and harmonic components. These outside-the-passband radio frequency components, on the one hand, can cause the signal processing module in the present invention to have input saturation problems, thereby affecting the signal processing module's processing of normal radio frequency signals. On the other hand, when the signal processing module processes normal radio frequency signals, due to the existence of the ubiquitous nonlinear amplification problem, there will be mixing of normal radio frequency signals with outside-the-passband radio frequency components, generating intermodulation frequency components, which will affect the normal operation of the entire SAR imaging system. These outside-the-passband radio frequency components and intermodulation frequency components flow into the downlink equipment of the present invention, such as an antenna, which will cause problems such as blurred imaging and increased deformation measurement errors.

[0069] Specifically, if Figure 2As shown, the first phase shifter includes a first pole, a second pole, and a third pole. The first and second poles are coupled via inductor L12, the first and third poles are coupled via inductor L13, and the second and third poles are coupled via inductor L23. The second phase shifter includes a fourth pole, a fifth pole, and a sixth pole. The fourth and fifth poles are coupled via inductor L45, the fifth and sixth poles are coupled via inductor L56, and the fourth and sixth poles are coupled via capacitor C46. Each pole—the first, second, third, fourth, fifth, and sixth poles—can be equivalent to an LC parallel resonant circuit, consisting of a parallel inductor and capacitor. The zero point position can be adjusted by adjusting the equivalent capacitance and inductance within the poles.

[0070] When the resonant frequency of the LC parallel resonant circuit (i.e., the pole) is f0, the pole-to-frequency i The RF signal with a frequency lower than the resonant frequency f0 is subjected to a +90° phase shift. i The RF signal with a frequency greater than the resonant frequency f0 is phase-shifted by -90°. The inductor between the poles performs a phase shift of -90° on the input RF signal, and the capacitor between the poles performs a phase shift of +90° on the input RF signal.

[0071] For the first phase shift unit (also called the tertiary pole), the path of the RF signal from the first pole (pole 1) through the second pole (pole 2) to the third pole (pole 3) is called branch 1, and the path of the RF signal from the first pole (pole 1) directly to the third pole (pole 3) is called branch 2.

[0072] When the frequency of the input RF signal f i When it is less than the resonant frequency f0, that is, f i When <f0, the phase shift of the RF signal on branch 1 of the first phase shift unit is:

[0073] +90° (pole 1) -90° (inductor L12) +90° (pole 2) -90° (inductor L23) +90° (pole 3) = +90°;

[0074] The phase shift of the RF signal on branch 2 of the first phase shift unit is:

[0075] +90° (pole 1) - 90° (inductor L13) + 90° (pole 3) = +90°.

[0076] Therefore, the first phase shift unit is i When the RF signal with a frequency lower than the resonant frequency f0 is subjected to phase shift processing, the outputs of the two branches are in phase.

[0077] When the input RF signal f i When it is greater than the resonant frequency f0, that is, f i When >f0, the phase shift of the RF signal on branch 1 is:

[0078] -90° (pole 1) -90° (inductor L12) -90° (pole 2) -90° (inductor L23) -90° (pole 3) = -90°;

[0079] The phase shift of the RF signal on branch 2 is:

[0080] -90° (pole 1) -90° (inductor L13) -90° (pole 3) = -270°;

[0081] Therefore, when the first phase shift unit is at the frequency f i When the RF signal with a frequency greater than the resonant frequency f0 is subjected to phase shift processing, the outputs of the two branches are in anti-phase, and the output results of the two branches can be offset after being superimposed on each other. Therefore, the first phase shift unit is at f i A zero point can be formed at some position of >f0.

[0082] For the second phase shift unit (also called the tertiary pole), the path of the RF signal from the fourth pole (pole 4) through the fifth pole (pole 5) to the sixth pole (pole 6) is called branch 1, and the path of the RF signal from the fourth pole (pole 4) directly to the sixth pole (pole 6) is called branch 2.

[0083] When the frequency of the input RF signal f i When it is less than the resonant frequency f0, that is, f i When <f0, the phase shift of the RF signal on branch 1 of the second phase shift unit is:

[0084] +90° (pole 4) -90° (inductor L45) +90° (pole 5) -90° (inductor L56) +90° (pole 6) = +90°;

[0085] The phase shift of the RF signal on branch 2 of the second phase shift unit is:

[0086] +90° (pole 4) + 90° (capacitor C46) + 90° (pole 6) = +270°;

[0087] Therefore, the second phase shift unit is i When the RF signal with a frequency lower than the resonant frequency f0 is subjected to phase shift processing, the outputs of the two branches are in the same and opposite phases, and the output results of the two branches can be canceled out after being superimposed on each other. Therefore, the second phase shift unit is at f i A zero point can be formed at a certain position of <f0.

[0088] When the frequency of the input RF signal f i When it is greater than the resonant frequency f0, that is, f i When >f0, the phase shift of the RF signal on branch 1 is:

[0089] -90° (pole 4) -90° (inductor L45) -90° (pole 5) -90° (inductor L56) -90° (pole 6) = -450°;

[0090] The phase shift of the RF signal on branch 2 is:

[0091] -90° (pole 4) + 90° (capacitor C46) - 90° (pole 6) = -90°;

[0092] Therefore, when the second phase shift unit is at the frequency f i When a radio frequency signal greater than the resonant frequency f0 is subjected to phase shift processing, the outputs of the two branches are in phase.

[0093] The first phase shift unit is at f i >f0 can form a zero point at a certain position, and the second phase shift unit is at f i <f0 can form a zero point at a certain position, and the first phase shift unit and the second phase shift unit can be connected in series to form a zero point at f i <f0 and f i The position of >f0 forms a zero point. By adjusting the equivalent inductance and equivalent capacitance inside the pole, the resonant frequency can be adjusted, thereby controlling the position of the zero point, changing the cutoff frequency and passband width of the bandpass filter, and realizing bandpass filtering of the input RF signal.

[0094] like Figure 3 As shown, the power splitter module includes a signal input channel and several signal output channels; the signal input channel is controlled by an external DC bias signal; each signal output channel includes a diode D connected in series i , D i ∈{D1,D2,…,D n} and capacitor C i , C i ∈{C 11 , C 21 ,…,C n1}. The diode D on each signal output channel i The anodes of diodes D i The cathode of the series capacitor C i , diode D i It is configured to control the conduction or cutoff of the signal output channel in response to an external DC bias signal.

[0095] Specifically, the power division module has a total signal input channel, which is connected to the output end of the filtering module. The signal input channel is correspondingly connected to N signal output channels (N = 1, 2, 3, ..., n). The number of signal output channels N corresponds to the number of array antennas, that is, signal output channel 1 outputs the RF signal to antenna 1, signal output channel 2 outputs the RF signal to antenna 2, signal output channel 3 outputs the RF signal to antenna 3, and signal output channel n outputs the RF signal to antenna n.

[0096] The working principle of the power divider module is as follows: a DC bias signal is added to the signal input channel of the power divider module. When the RF signal needs to be transmitted to antenna 1 through output channel 1, the control end of control signal output channel 1 is connected to the power ground, and the control ends of other signal output channels except signal output channel 1 are left floating. The diode D1 on signal output channel 1 is turned on, and the RF signal is output through the diode D1 and capacitor C1 of output channel 1. Similarly, when the RF signal needs to be transmitted to antenna 2 through signal output channel 2, the control end of control signal output channel 2 is connected to the power ground, and the control ends of other signal output channels except signal output channel 2 are left floating. The diode D2 on signal output channel 2 is turned on, and the RF signal is output through the diode D2 and capacitor C2 of signal output channel 2. In actual implementation, a capacitor C1 is set on the signal input channel as an AC coupling to prevent the DC bias signal inside the power divider module from overflowing to the outside of the power divider module and affecting the operation of the front-stage circuit of the power divider module; an inductor L is set on the control end of each signal output channel of the power divider module. i , which can suppress the RF signal from escaping to the control end of the signal output channel. At the same time, the capacitor C on the signal output channel i This prevents the DC bias signal introduced by the next-stage circuit from affecting the diode's opening and closing. The power divider module provides a certain degree of isolation between the various signal output channels, reducing mutual interference between channels and improving signal quality and system reliability.

[0097] In one embodiment, the signal processing unit includes a power amplifier and a switch control circuit, which is used to control the power amplifier's on and off state. Specifically, each signal output channel of the power splitter module is connected to a power amplifier for amplifying or suppressing the RF signal output by that signal output channel. Each power amplifier corresponds to a switch control circuit, which controls the power amplifier's on and off state.

[0098] like Figure 4As shown, the switch control circuit around the power amplifier includes: an analog single-pole double-throw switch, a positive power supply current sensor, an analog-to-digital converter, and an integrated operational amplifier; wherein the output end of the analog single-pole double-throw switch is connected to the input end of the positive power supply current sensor, the first output end of the positive power supply current sensor is connected to the positive power supply input end of the power amplifier, the second output end of the positive power supply current sensor is connected to the input end of the analog-to-digital converter, the output end of the analog-to-digital converter is connected to the input end of the integrated operational amplifier, and the output end of the integrated operational amplifier is connected to the negative power supply input end of the power amplifier.

[0099] When the switch control circuit receives an enable signal, it controls the internal analog single-pole double-throw switch to connect to the operating voltage. This operating voltage is fed into the power amplifier's positive power input via a positive power current sensor, providing a positive voltage for the amplifier. When the switch control circuit receives a channel enable signal, the analog-to-digital converter's output voltage enters the operating range and is fed into the integrated operational amplifier. After inversion, this voltage is then output to the amplifier's negative power input. The amplifier then begins operating, opening the corresponding RF signal channel and transmitting the processed RF signal to the target antenna. When the switch control module receives a channel disable signal, the analog-to-digital converter's output voltage increases to a preset sleep voltage, connecting the analog single-pole double-throw switch to power ground. The amplifier shuts down and enters a sleep state, awaiting the next trigger.

[0100] In some preferred embodiments, Figure 5 As shown, a closed-loop control unit is provided between the second output terminal of the positive power supply current sensor and the input terminal of the analog-to-digital converter. The closed-loop control unit is configured to obtain the positive power supply current value of the positive power supply current sensor, convert the positive power supply current value into a digital voltage using an improved PID algorithm, and transmit the digital voltage to the analog-to-digital converter. The improved PID algorithm is used to close-loop control the negative power supply voltage, so that the power amplifier operates in an optimal state.

[0101] Among them, Figure 6 The closed-loop control unit is configured as follows: the analog-to-digital converter receives the positive power supply current i of the positive current sensor n , based on the positive supply current i n and the desired current set by the switch control circuit Calculate the positive power supply current i n and the expected current The current error is:

[0102] e[n] is the positive power supply current i n and the expected current The current error between

[0103] Perform proportional operation on the current error e[n]: p k [n] = k p *e[n],

[0104] Where k p is the scaling factor, p k [n] is the output result of the nth proportional operation.

[0105] Perform time-compensated integration on the current error to obtain the error integral result. The formula is as follows:

[0106] i k [n]=i k [n-1]+k i *e[n]*δt,

[0107] Where k i is the integral factor, δt is the time difference between the last PID algorithm and the current PID algorithm, i k [n] represents the nth integral output, i k [n-1] represents the n-1th integral output;

[0108] Perform time-compensated differential operation on the current error to obtain the error differential result. The formula is as follows:

[0109]

[0110] Where k d is the differential factor, d k [n] is the nth differential output;

[0111] Superimpose the above proportional operation results, error integral results and error differential results:

[0112] a[n]=p k [n]+i k [n]+d k [n],

[0113] Where, a[n] represents the nth superposition result;

[0114] Perform impulse calculation on the superposition result to obtain the impulse calculation result:

[0115] b[n]=(1-λ)*a[n]+λ*a[n-1],

[0116] Where λ represents the impulse factor, b[n] represents the result of the n-th impulse calculation;

[0117] The digital voltage is determined based on the impulse calculation result and input into the analog-to-digital converter. The formula is expressed as:

[0118]

[0119] Where th represents the dead-band threshold of the dead-band clamp, c[n] represents the nth output of the dead-band clamp, and when the absolute value of b[n] is less than the dead-band threshold th, the dead-band clamp output is 0. When the absolute value of b[n] is greater than or equal to the dead-band threshold th, the dead-band clamp output is the nth impulse calculation result, b[n]. The outputs of the dead-band clamp are accumulated to obtain a digital voltage, which is then input into an analog-to-digital converter to achieve closed-loop control of the power amplifier.

[0120] Another embodiment of the present application also provides a channel switching method for ground-based SAR, such as Figure 7 As shown, the method includes:

[0121] S1: The filtering module receives the RF signal from the signal source, filters the RF signal, and inputs the filtered RF signal to the power splitter module;

[0122] S2: Under the control of an external signal, the power splitter module turns on one of the signal output channels, so that the filtered RF signal is output through the turned-on signal output channel.

[0123] S3: The signal processing module amplifies or suppresses the RF signal output by the power splitter module and transmits the processed RF signal to the target antenna.

[0124] In some embodiments, the filtering module is at least one of a bandpass filter, a low-pass filter, or a high-pass filter.

[0125] In some embodiments, the filtering module is a bandpass filter, which is composed of a first phase shifter unit and a second phase shifter unit connected in series; the filtering module receives the radio frequency signal from the signal source and performs filtering processing on the radio frequency signal, including: forming a first zero point position of the radio frequency signal through the first phase shifter unit, and forming a second zero point position of the radio frequency signal through the second phase shifter unit.

[0126] In some embodiments, the power division module includes a signal input channel and several signal output channels; the signal input channel is controlled by an external DC bias signal; each signal output channel includes a diode and a capacitor connected in series, the anode of the diode is connected to the signal input channel, and the cathode of the diode is connected in series with the capacitor, and the diode is configured to control the conduction or cutoff of the output channel in response to the external DC bias signal.

[0127] In some embodiments, each signal processing unit includes a power amplifier and a switch control circuit. The power amplifier amplifies or suppresses the RF signal output by the power splitter module under the control of the switch control circuit, and transmits the processed RF signal to the target antenna.

[0128] In some embodiments, the switch control circuit receives the positive power supply current from the positive power supply sensor, converts the positive power supply current into a digital voltage through an improved PID algorithm, and further transmits the digital voltage to the analog-to-digital converter. The integrated operational amplifier is used to calculate the negative power supply voltage of the power amplifier, so that the power amplifier operates in an optimal state.

[0129] The specific definition of the channel switching method of the ground-based SAR provided in this embodiment can be found in the embodiment of the channel switching system of the ground-based SAR above, and will not be repeated here.

[0130] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0131] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] Those skilled in the art will clearly understand that for the sake of convenience and brevity of description, the division of the above-mentioned functional units and modules is only used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the system described in this application is divided into different functional units or modules to complete all or part of the functions described above.

Claims

1. A channel switching system for ground-based SAR, characterized in that: include: A filtering module, used for filtering the input radio frequency signal; A power splitter module includes a plurality of signal output channels. The power splitter module is configured to, in response to control by an external signal, turn on one of the plurality of signal output channels so that the filtered radio frequency signal is output through the turned-on signal output channel. The power splitter module includes a signal input channel and a plurality of signal output channels. The signal input channel is controlled by an external DC bias signal. Each signal output channel includes a diode and a capacitor connected in series. The anode of the diode is connected to the signal input channel, and the cathode of the diode is connected in series with the capacitor. The diode is configured to control the conduction or cutoff of the output channel in response to the external DC bias signal. The signal processing module includes several signal processing units, each of which is connected to a signal output channel of the power division module, and is used to receive the radio frequency signal output by the corresponding signal output channel and amplify or suppress the radio frequency signal.

2. The channel switching system for ground-based SAR according to claim 1, characterized in that: The filtering module includes at least one of a bandpass filter, a low-pass filter or a high-pass filter.

3. The channel switching system for ground-based SAR according to claim 2, characterized in that: The filtering module is a bandpass filter; The bandpass filter is composed of a first phase shift unit and a second phase shift unit connected in series; The first phase shift unit is used to form a first zero point position for the input radio frequency signal, The second phase shift unit is used to form a second zero point position for the input radio frequency signal.

4. The channel switching system for ground-based SAR according to claim 3, characterized in that: The first phase shift unit includes a first pole, a second pole and a third pole, wherein the first pole and the second pole are coupled by an inductor, the first pole and the third pole are coupled by an inductor, and the second pole and the third pole are coupled by an inductor; The second phase shift unit includes a fourth pole, a fifth pole and a sixth pole. The fourth pole and the fifth pole are coupled by an inductor, the fifth pole and the sixth pole are coupled by an inductor, and the fourth pole and the sixth pole are coupled by a capacitor.

5. The channel switching system for ground-based SAR according to claim 4, characterized in that: The first pole, the second pole, the third pole, the fourth pole, the fifth pole and the sixth pole are all composed of parallel LC resonant circuits.

6. The channel switching system for ground-based SAR according to claim 1, characterized in that: The signal processing unit includes a power amplifier and a switch control circuit, and the switch control circuit is used to control the switching of the power amplifier.

7. The channel switching system for ground-based SAR according to claim 6, characterized in that: The switch control circuit includes: an analog single-pole double-throw switch, a positive power supply current sensor, an analog-to-digital converter and an integrated operational amplifier; The output end of the single-pole double-throw switch is connected to the input end of the positive power supply current sensor, the first output end of the positive power supply current sensor is connected to the positive power supply input end of the power amplifier, the second output end of the positive power supply current sensor is connected to the input end of the analog-to-digital converter, the output end of the analog-to-digital converter is connected to the input end of the integrated operational amplifier, and the output end of the integrated operational amplifier is connected to the negative power supply input end of the power amplifier.

8. The channel switching system for ground-based SAR according to claim 7, characterized in that: A closed-loop control unit is also included between the second output terminal of the positive power supply current sensor and the input terminal of the analog-to-digital converter. The closed-loop control unit is configured to obtain the positive power supply current value of the positive power supply current sensor, convert the positive power supply current value into a digital voltage using an improved PID algorithm, and transmit the digital voltage to the analog-to-digital converter.

9. The channel switching system for ground-based SAR according to claim 8, characterized in that: The closed-loop control unit is configured as: receiving a positive power supply current from a positive current sensor, and calculating a current error based on the positive power supply current and an expected current; Perform proportional operation on the current error to obtain the proportional operation result; Perform time-compensated integration on the current error to obtain the error integration result; Perform time-compensated differential operation on the current error to obtain the error differential result; Superimposing the proportional operation result, the error integral result, and the error differential result, and performing impulse operation on the superimposed result to obtain an impulse operation result; A digital voltage is determined based on the impulse calculation result, and the digital voltage is output to an analog-to-digital converter.

10. A channel switching method for ground-based SAR, characterized in that: include: The filtering module receives the RF signal from the signal source, filters the RF signal, and inputs the filtered RF signal to the power splitter module; The power splitter module, under the control of an external signal, turns on one of the plurality of signal output channels, so that the filtered radio frequency signal is output through the turned-on signal output channel. The power splitter module includes a signal input channel and a plurality of signal output channels, wherein the signal input channel is controlled by an external DC bias signal, and each signal output channel includes a diode and a capacitor connected in series, wherein the anode of the diode is connected to the signal input channel, and the cathode of the diode is connected in series with the capacitor, and the diode is configured to control the conduction or cutoff of the output channel in response to the external DC bias signal. The signal processing unit of the control signal processing module amplifies or suppresses the radio frequency signal output by the corresponding power division module, and transmits the processed radio frequency signal to the target antenna.

11. The channel switching method for ground-based SAR according to claim 10, characterized in that: The filtering module is at least one of a bandpass filter, a low-pass filter or a high-pass filter.

12. The channel switching method for ground-based SAR according to claim 11, characterized in that: The filtering module is a bandpass filter, which is composed of a first phase shift unit and a second phase shift unit connected in series. The filtering module receives the RF signal from the signal source and performs filtering on the RF signal, including: A first zero point position is formed for the radio frequency signal by the first phase shift unit, and a second zero point position is formed for the radio frequency signal by the second phase shift unit.

13. The channel switching method for ground-based SAR according to claim 10, characterized in that: Each signal processing unit includes a power amplifier and a switch control circuit. The signal processing unit of the control signal processing module amplifies or suppresses the RF signal output by the corresponding power splitter module and transmits the processed RF signal to the target antenna, including: The power amplifier, under the control of the switch control circuit, amplifies or suppresses the RF signal output by the power divider module and transmits the processed RF signal to the target antenna.

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