A frequency source system and frequency modulation method thereof, and radar

Abstract

The embodiment of the present application provides a frequency source system and a frequency modulation method thereof, and a radar, which relates to the field of radar technology and is used to improve the signal modulation speed of the frequency source system. The frequency source system includes: an oscillator, a closed-loop control branch, an open-loop control branch, and a calibration branch; the oscillator is used to output a signal of a corresponding frequency based on a first signal output by the closed-loop control branch and a second signal output by the open-loop control branch; the closed-loop control branch is used to output a first signal to the oscillator based on a reference frequency and the frequency of the signal output by the oscillator; the open-loop control branch is used to output a second signal to the oscillator based on a target digital codeword, and the target digital codeword corresponds to the expected frequency of the signal output by the oscillator; the calibration branch is connected to the first end of the closed-loop control branch and is also connected to the open-loop control branch, and the calibration branch is used to provide calibration information to the open-loop control branch based on the first signal, so that the open-loop control branch adjusts the second signal output to the oscillator based on the calibration information.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a frequency source system and a frequency modulation method thereof, and a radar. Background Art

[0002] The frequency source system in radar refers to the component or subsystem that provides stable and accurate frequency signals for radar. It is one of the core components of the radar system and has an important impact on the performance and stability of the radar. The frequency source system is mainly used to generate stable frequency signals and provide multiple frequency outputs. The phase-locked loop in the frequency source system can generate stable and adjustable frequency signals by adjusting the parameters of its oscillator and controlling the characteristics of the loop filter. This is crucial for radar systems because radars require high-precision frequency sources to ensure detection accuracy.

[0003] The modulation speed of the frequency source system is closely related to the resolution of the radar. By increasing the modulation speed of the frequency source system, the radar system can change the parameters of the transmitted signal (such as frequency, amplitude, phase, etc.) more quickly, thereby enhancing the ability to resolve the target object. Therefore, it is necessary to increase the modulation speed of the frequency source system, that is, the speed at which the frequency source system adjusts the output frequency. Summary of the invention

[0004] The present application provides a frequency source system and a frequency modulation method thereof, and a radar, which are used to reduce the voltage fluctuation in a closed-loop control branch of the frequency source system, thereby improving the signal modulation speed of the frequency source system.

[0005] The first aspect of the embodiment of the present application provides a frequency source system, including: an oscillator, a closed-loop control branch, an open-loop control branch and a calibration branch. The oscillator is used to output a signal of a corresponding frequency based on a first signal output by the closed-loop control branch and a second signal output by the open-loop control branch. The first end of the closed-loop control branch is connected to the first input end of the oscillator, and the second end of the closed-loop control branch is connected to the output end of the oscillator. The closed-loop control branch is used to output a first signal to the oscillator based on a reference frequency and the frequency of the signal output by the oscillator. The open-loop control branch is connected to the second input end of the oscillator, and the open-loop control branch is used to output a second signal to the oscillator based on a target digital codeword, and the target digital codeword corresponds to the expected frequency of the signal output by the oscillator. The calibration branch is connected to the first end of the closed-loop control branch and is also connected to the open-loop control branch. The calibration branch is used to provide calibration information to the open-loop control branch based on the first signal, so that the open-loop control branch adjusts the second signal output to the oscillator based on the calibration information.

[0006] It can be seen that the frequency source system provided by the embodiment of the present application, by setting a calibration branch between the closed-loop control branch (the closed-loop control branch and the oscillator form a phase-locked loop) and the open-loop control branch, obtains the first signal output by the closed-loop control branch to the oscillator through the calibration branch. Since the first signal is generated by the closed-loop control branch, it can be used to indicate the working state of the closed-loop control branch. Since the closed-loop control branch will automatically adjust according to the error of the output frequency, the calibration information determined by the calibration branch based on the first signal can be used to reflect the fluctuations caused by the closed-loop control branch due to the correction of the frequency modulation error. Then the calibration branch provides calibration information to the open-loop control branch, so that the open-loop control branch adjusts the second signal output to the oscillator based on the calibration information, so that the open-loop control branch corrects the frequency modulation error, thereby avoiding the fluctuation of the closed-loop control branch. It can be seen that the adjustment of the open-loop control branch is direct and does not depend on the output feedback of the system, so it has a faster response speed, thereby improving the modulation speed of the frequency source system. Furthermore, by accurately calibrating the target digital codeword through the first signal, the system can reduce oscillations caused by mismatching between the closed-loop control branch and the open-loop control branch, thereby improving the overall stability of the system.

[0007] In combination with the first implementation of the first aspect, the calibration branch is used to provide calibration information to the open-loop control branch based on the fluctuation of the first signal, and the calibration information is used to calibrate the target digital codeword. The open-loop control branch is configured to: calibrate the target digital codeword based on the calibration information to obtain a calibrated target digital codeword, and output a second signal to the oscillator based on the calibrated target digital codeword.

[0008] In combination with the second implementation of the first aspect, the oscillator is a voltage-controlled oscillator, the first signal is a first voltage signal, and the second signal is a second voltage signal. Alternatively, the oscillator is a digitally controlled oscillator, the first signal is a first digital signal, and the second signal is a second digital signal.

[0009] In combination with the third implementation of the first aspect, when the oscillator is a voltage-controlled oscillator, the open-loop control branch includes: a first storage module and a digital-to-analog converter. The first input end of the first storage module is used to receive the target frequency corresponding to the desired frequency, the second input end of the first storage module is connected to the calibration branch to receive calibration information, and the output end of the first storage module is connected to the input end of the digital-to-analog converter. The first storage module stores the correspondence between digital codewords and frequency points. The first storage module is used to find the target digital codeword from multiple data codewords in the correspondence based on the target frequency point, and output it to the digital-to-analog converter. The output end of the digital-to-analog converter is connected to the second input end of the oscillator. The digital-to-analog converter is used to receive the target digital codeword output by the first storage module, and output a second voltage signal corresponding to the target digital codeword to the oscillator.

[0010] In combination with the fourth implementation of the first aspect, the calibration branch includes: a calibration module, a second storage module and an analog-to-digital converter. The input end of the analog-to-digital converter is connected to the first end of the closed-loop control branch, and the output end of the analog-to-digital converter is connected to the input end of the second storage module. The analog-to-digital converter is used to obtain a first voltage signal from the first end of the closed-loop control branch, and store a digital codeword corresponding to the first voltage signal in the second storage module. The input end of the calibration module is connected to the output end of the second storage module, and the output end of the calibration module is connected to the second input end of the first storage module. The calibration module is used to calibrate the target digital codeword in the first storage module based on the digital codeword corresponding to the first voltage signal stored in the second storage module and the gain relationship between the closed-loop control branch and the open-loop control branch.

[0011] In conjunction with the fifth implementation of the first aspect, the calibrated target digital codeword satisfies the following relationship:

[0012] V2[n]=V2'[n]+k×(V1[n]- V1[0]).

[0013] Among them, the frequency point corresponding to the target digital codeword is the nth frequency point. V2[n] is the target digital codeword after calibration. V2'[n] is the target digital codeword before calibration. V1[n] is the digital codeword corresponding to the first voltage signal obtained from the first end of the closed-loop control branch at the nth frequency point. V1[0] is the starting codeword. k is the gain coefficient of the open-loop control branch compared to the closed-loop control branch.

[0014] In combination with the sixth implementation of the first aspect, when the oscillator is a voltage-controlled oscillator, the open-loop control branch includes: a digital-to-analog converter. A first input end of the digital-to-analog converter is used to receive a target digital codeword, a second input end of the digital-to-analog converter is connected to the calibration branch to receive calibration information, and an output end of the digital-to-analog converter is connected to a second input end of the oscillator. The digital-to-analog converter is used to output a second voltage signal to the oscillator based on the target digital codeword and the calibration information.

[0015] In combination with the seventh implementation of the first aspect, the calibration branch includes: an analog-to-digital converter and a calibration module. The input end of the analog-to-digital converter is connected to the first end of the closed-loop control branch, and the output end of the analog-to-digital converter is connected to the input end of the calibration module. The analog-to-digital converter is used to obtain a first voltage signal from the first end of the closed-loop control branch, and output a digital codeword corresponding to the first voltage signal to the calibration module. The output end of the calibration module is connected to the second input end of the digital-to-analog converter. The calibration module is used to determine the calibration codeword based on the digital codeword corresponding to the first voltage signal in the first clock cycle and the digital codeword corresponding to the first voltage signal in the second clock cycle, and output the calibration codeword as calibration information to the digital-to-analog converter. The first clock cycle and the second clock cycle are before the current clock cycle, and the first clock cycle and the second clock cycle are two adjacent clock cycles. The digital-to-analog converter is also used to output a second voltage signal to the oscillator based on the target digital codeword and the calibration codeword.

[0016] In combination with the eighth implementation method of the first aspect, the calibration module is specifically used to determine the calibration codeword based on the digital codeword corresponding to the first voltage signal obtained in the first clock cycle, the digital codeword corresponding to the first voltage signal obtained in the second clock cycle, and the gain relationship between the closed-loop control branch and the open-loop control branch.

[0017] The second aspect of the embodiment of the present application provides a radar, which includes a radio frequency transceiver system and a frequency source system provided by the first aspect and its possible implementation. The radio frequency transceiver system is connected to the frequency source system, and the frequency source system is used to provide different frequencies for the radio frequency transceiver system.

[0018] A third aspect of an embodiment of the present application provides a frequency modulation method for a frequency source system. The frequency source system is the frequency source system provided by the first aspect and its possible implementation method. The frequency modulation method includes: acquiring a first signal in a closed-loop control branch; adjusting a second signal output by an open-loop control branch based on the first signal to adjust the output frequency of the oscillator.

[0019] In combination with the first implementation manner of the third aspect, adjusting the second signal output by the open-loop control branch based on the first signal includes: adjusting the second signal output by the open-loop control branch based on fluctuations of the first signal.

[0020] In combination with the second implementation method of the third aspect, the second signal output by the open-loop control branch is adjusted based on the fluctuation of the first signal, including: providing calibration information to the open-loop control branch based on the fluctuation of the first signal and the gain relationship between the closed-loop control branch and the open-loop control branch; so that the open-loop control branch adjusts the output second signal based on the calibration information.

[0021] Among them, the beneficial effects described in the second and third aspects can refer to the beneficial effect analysis of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0023] Figure 1 A schematic diagram of the structure of a phase-locked loop provided in an embodiment of the present application;

[0024] Figure 2 A schematic diagram of the structure of a two-point modulation phase-locked loop provided in an embodiment of the present application;

[0025] Figure 3 A schematic diagram of a frequency source system provided in an embodiment of the present application Figure 1 ;

[0026] Figure 4 A schematic diagram of a frequency source system provided in an embodiment of the present application Figure 2 ;

[0027] Figure 5 A schematic diagram of the overall structure of a frequency source system provided in an embodiment of the present application;

[0028] Figure 6 A schematic diagram of a frequency source system provided in an embodiment of the present application Figure 3 ;

[0029] Figure 7 A schematic diagram of the overall structure of another frequency source system provided in an embodiment of the present application;

[0030] Figure 8 A schematic diagram of the overall structure of another frequency source system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0033] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances. In addition, when describing a pipeline, the "connected" and "connection" used in this application have the meaning of conduction. The specific meaning needs to be understood in conjunction with the context.

[0034] 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.

[0035] The frequency source system in radar refers to the component or subsystem that provides stable and accurate frequency signals for radar. It is one of the core components of the radar system and has an important impact on the performance and stability of the radar. The frequency source system is mainly used to generate stable frequency signals and provide multiple frequency outputs. The phase-locked loop in the frequency source system can generate stable and adjustable frequency signals by adjusting the parameters of its voltage-controlled oscillator and the characteristics of the control loop filter.

[0036] A phase-locked loop is a frequency source circuit that can generate a target frequency signal according to a digital codeword configuration, and the actual output frequency has a small error with the target frequency. For example, see Figure 1 The phase-locked loop is composed of modules such as frequency detector, loop filter, frequency divider, oscillator, etc., among which the oscillator is the frequency generation module in the phase-locked loop, and the remaining modules are used to achieve frequency calibration.

[0037] It should be understood that, for ease of description, the embodiments of the present application are described by taking the oscillator as a voltage-controlled oscillator as an example, that is, the oscillator outputs a corresponding frequency according to the received voltage signal. In practical applications, the oscillator can also be a digitally controlled oscillator, that is, it outputs a corresponding frequency according to the received digital signal, and the embodiments of the present application do not limit the specific form of the oscillator.

[0038] In a phase-locked loop, the reference frequency of the input signal is usually stable, while the frequency of the output signal can be adjusted by adjusting the frequency division ratio. Figure 1As shown, the phase-locked loop includes a frequency divider, which is used to reduce the frequency of the output signal of the oscillator by N times according to the received frequency division ratio N, and generate a feedback signal to output to the phase frequency detector. The phase frequency detector is used to output a voltage signal according to the frequency difference between the reference frequency of the input signal and the frequency of the feedback signal. Since the output signal of the phase frequency detector usually contains high-frequency noise and unstable factors, a loop filter is required to filter the output signal of the phase frequency detector to remove high-frequency noise and clutter, so as to obtain a relatively smooth control voltage signal, and then adjust the output frequency of the oscillator.

[0039] Since the working environment of radar may be very complex, including different weather conditions, terrain and electromagnetic environment, etc. In order to improve the accuracy of radar detection, it is necessary to perform frequency sweep modulation on the radar before detection so that the radar can adapt to these environmental changes and maintain stable detection performance.

[0040] Sweep frequency modulation detects targets by changing the frequency of the transmitted signal. When the transmitted signal encounters the target, it will be reflected back to form an echo signal. By comparing the frequency difference between the transmitted signal and the echo signal, the distance and speed between the target and the radar can be calculated. It can be seen that the frequency of the transmitted signal, that is, the frequency of the oscillator output signal in the frequency source system, needs to be changed during the swept frequency modulation process.

[0041] Adjusting the frequency of the oscillator output signal is to adjust the strength of the voltage signal received by the oscillator. When the strength of the voltage signal received by the oscillator is adjusted only by the frequency division ratio in the phase-locked loop, the voltage in the phase-locked loop will change. However, since the phase-locked loop is a closed-loop system, the rate of change of the voltage in the phase-locked loop is limited by the loop. For example, when the loop filter filters the output signal of the frequency detector and phase detector, a certain delay will be introduced. This delay will limit the rate of change of the control voltage signal, thereby affecting the adjustment speed of the oscillator output signal frequency, resulting in a slower radar modulation rate.

[0042] In order to improve the modulation speed of the radar, the frequency source system can also include an open-loop control branch. The output end of the open-loop control branch is connected to the voltage-controlled oscillator. When the radar performs swept frequency modulation, the frequency of the output signal of the voltage-controlled oscillator is adjusted through the open-loop control branch. The voltage in the phase-locked loop does not fluctuate, and the response speed of the phase-locked loop will not affect the radar modulation speed, thereby improving the radar modulation speed.

[0043] Exemplary, combined Figure 1 , see Figure 2 , a waveform generator and an open-loop control branch can be set in the frequency source system, and the open-loop control branch can include a Vctrl lookup table and a digital-to-analog converter.

[0044] The Vctrl lookup table is a storage module for storing the correspondence between frequency points and digital codewords. In the swept frequency modulation process of the radar, the waveform generator can determine a target frequency point and a frequency division ratio N based on the expected output frequency of the VCO, output the frequency division ratio N to the frequency divider in the phase-locked loop, and output the target frequency point to the Vctrl lookup table, so that the Vctrl lookup table sends the target digital codeword corresponding to the target frequency point to the digital-to-analog converter.

[0045] The relationship between the digital codeword, the reference frequency and the output frequency can be expressed as: output frequency (Fout) = reference frequency (Fref) × frequency division ratio (N / M), where N and M are parameters controlled by the digital codeword. It is understandable that in some cases, the frequency division ratio may be directly determined by the digital codeword, that is, N=f(digital codeword), and M is a constant or is also affected by the digital codeword, which is not limited in the embodiments of the present application.

[0046] The digital-to-analog converter is used to convert digital signals into analog voltage signals. It is understandable that the signal that can be calculated and processed is a digital signal, which is a data composed of a number of 0s and 1s, that is, a digital codeword. And the voltage-controlled oscillator can be controlled by a voltage signal. Therefore, the open-loop control branch needs to convert the digital signal into an analog voltage signal through a digital-to-analog converter to adjust the output frequency of the voltage-controlled oscillator.

[0047] Under ideal conditions, the modulation of the VCO output frequency is completed by adjusting the target digital codeword in the open-loop control branch. During the modulation process, the voltage in the phase-locked loop remains unchanged, so the response speed of the phase-locked loop will not affect the output frequency modulation speed, thereby improving the modulation speed of the radar.

[0048] However, in actual applications, the signal modulation in the open-loop control branch is not ideal. This may be due to the nonlinearity of a certain component, noise interference, or mismatch of circuit components, which leads to a mismatch between the open-loop control branch and the phase-locked loop. In the radar signal modulation, the phase-locked loop will automatically correct the frequency modulation error of the open-loop control branch, causing the voltage in the phase-locked loop to fluctuate. Due to the voltage fluctuation in the phase-locked loop, the radar modulation speed will be affected by the response speed of the phase-locked loop and become lower.

[0049] Based on this, the present application embodiment provides a frequency source system, see Figure 3 The frequency source system 30 provided in the embodiment of the present application includes: an oscillator 31, a closed-loop control branch 32, an open-loop control branch 33 and a calibration branch 34.

[0050] The oscillator 31 is used to output a signal of a corresponding frequency based on a first signal output by the closed-loop control branch and a second signal output by the open-loop control branch.

[0051] It should be understood that the oscillator 31 may be a voltage-controlled oscillator or a digitally controlled oscillator, which may be determined according to actual application requirements, and the embodiments of the present application do not limit this.

[0052] As a feasible implementation, when the oscillator 31 is a voltage-controlled oscillator, the first signal is a first voltage signal, and the second signal is a second voltage signal. The oscillator is used to generate a signal of a corresponding frequency based on the first voltage signal and the second voltage signal.

[0053] For example, a voltage-controlled oscillator is usually composed of the following key parts: an oscillation circuit, which is the core part of generating the oscillation signal, and may use an LC oscillator, an RC oscillator or other types of oscillation circuits; a voltage control part, which is responsible for converting the external input voltage into a signal that can affect the oscillation frequency; an output buffer, in order to provide a stable output signal, a voltage-controlled oscillator usually includes an output buffer for isolating the oscillation circuit from the external load, thereby maintaining the stability of the oscillator.

[0054] It should be understood that the first voltage signal output by the closed-loop control branch to the oscillator can be called a tuning voltage (Vtune); the second voltage signal output by the open-loop control branch to the oscillator can also be called a control voltage (Vctrl), and this application does not impose any restrictions on this.

[0055] As another feasible implementation, when the oscillator 31 is a digitally controlled oscillator, the first signal is a first digital signal, and the second signal is a second digital signal. The digitally controlled oscillator generates a signal of corresponding frequency based on the first digital signal and the second digital signal.

[0056] like Figure 3 As shown, the first end 32-1 of the closed-loop control branch 32 is connected to the first input end 31-1 of the oscillator 31, and the second end 32-2 of the closed-loop control branch is connected to the output end 31-2 of the oscillator. The closed-loop control branch 32 is used to output a first signal to the oscillator based on the frequency of the signal output by the oscillator and the reference frequency.

[0057] As a feasible implementation method, the closed-loop control branch may include: a frequency divider, a loop filter and a frequency detector; the frequency divider is used to output a feedback frequency to the frequency detector based on the frequency of the signal output by the oscillator and the frequency division ratio; the frequency detector is used to output a first voltage signal based on the error between the reference frequency and the feedback frequency; the loop filter is used to filter the frequency output by the frequency detector to obtain a relatively stable first voltage signal.

[0058] As another feasible implementation method, when the oscillator is a digitally controlled oscillator, the closed-loop control branch may also include: an analog-to-digital converter, which is used to convert the first voltage signal output by the loop filter into a digital signal, and then output it to the digitally controlled oscillator, so that the digitally controlled oscillator outputs a signal of corresponding frequency.

[0059] It can be understood that the closed-loop control branch 32 and the oscillator 31 in the embodiment of the present application can be regarded as the phase-locked loop in the above embodiment, and its specific working principle can refer to the above embodiment, which will not be repeated in this application.

[0060] Since the output frequency of the oscillator 31 needs to be adjusted during the signal modulation process, that is, the input signal of the oscillator 31 needs to be adjusted, and when the output signal of the closed-loop control branch 32 is adjusted, the rate of change of the signal is limited by the loop formed by the closed-loop control branch 32 and the oscillator 31, resulting in a relatively slow change of the signal in the closed-loop control branch 32.

[0061] Therefore, if Figure 3 As shown, the frequency source system in the embodiment of the present application further includes an open-loop control branch 33. A first end 33-1 of the open-loop control branch 33 is connected to a second input end 31-3 of the oscillator 31, and the open-loop control branch is used to output a second signal to the oscillator based on the target digital codeword.

[0062] The target digital codeword corresponds to the expected frequency of the signal output by the oscillator. That is, the frequency source system can adjust the expected frequency of the oscillator output signal by adjusting the target digital codeword without adjusting the signal in the closed-loop control branch 32, thereby avoiding the fluctuation of the signal in the closed-loop control branch 32 affecting the adjustment speed of the output frequency of the oscillator 31.

[0063] In this application example, please continue to refer to Figure 3 The frequency source system provided in the embodiment of the present application also includes a calibration branch 34, a first end 34-1 of the calibration branch is connected to the first end 32-1 of the closed-loop control branch 32, and a second end 34-2 of the calibration branch is connected to the second end 33-2 of the open-loop control branch 33.

[0064] In the embodiment of the present application, the calibration branch 34 is used to provide calibration information to the open-loop control branch based on the first signal, so that the open-loop control branch 33 adjusts the second signal output to the oscillator based on the calibration information.

[0065] It can be seen that the frequency source system provided by the embodiment of the present application, by setting a calibration branch between the closed-loop control branch and the open-loop control branch, obtains the first signal output by the closed-loop control branch to the oscillator through the calibration branch, and since the first signal is generated by the closed-loop control branch, it can be used to indicate the working state of the closed-loop control branch. Since the closed-loop control branch will automatically adjust according to the error of the output frequency, the calibration information determined by the calibration branch based on the first signal can be used to reflect the fluctuations caused by the closed-loop control branch due to the correction of the frequency modulation error. Then the calibration branch provides calibration information to the open-loop control branch, so that the open-loop control branch adjusts the second signal output to the oscillator based on the calibration information, so that the open-loop control branch corrects the frequency modulation error, thereby avoiding the fluctuation of the closed-loop control branch. It can be seen that the adjustment of the open-loop control branch is direct and does not depend on the output feedback of the system, so it has a faster response speed, thereby improving the modulation speed of the frequency source system. In addition, by accurately calibrating the target digital codeword through the first signal, the system can reduce the oscillation caused by the mismatch between the closed-loop control branch and the open-loop control branch, and improve the overall stability of the system.

[0066] In some embodiments, since the purpose of calibrating the target digital codeword is to prevent the signal in the closed-loop control branch from fluctuating, thereby increasing the modulation speed of the frequency source system, calibration can be performed based on the fluctuation of the signal in the closed-loop control branch.

[0067] Specifically, as a feasible implementation method, the calibration branch is used to provide calibration information to the open-loop control branch based on the fluctuation of the first signal, and the calibration information is used to calibrate the target digital codeword. The open-loop control branch is configured to: calibrate the target digital codeword based on the calibration information to obtain a calibrated target digital codeword, and output a second voltage signal to the oscillator based on the calibrated target digital codeword.

[0068] It can be understood that the calibration branch determines the calibration information based on the fluctuation of the first signal of the closed-loop control branch. Since the fluctuation of the first signal can accurately reflect the difference between the current state and the expected state of the closed-loop control branch, the calibration branch determines the calibration information based on the fluctuation of this precise first signal. The obtained calibration information can be used to accurately measure the frequency modulation error of the frequency source system. The open-loop control branch calibrates the target digital codeword according to the calibration information, and can quickly adjust the second signal received by the oscillator so that the second signal can compensate for the frequency modulation error in time. That is, the error is adjusted through the open-loop control branch, so that the closed-loop control branch. This adjustment is direct and does not depend on the output feedback of the system, so it has a faster response speed, thereby improving the modulation speed of the frequency source system.

[0069] It should be understood that the oscillator 31 in the embodiment of the present application can be a voltage-controlled oscillator or a digitally controlled oscillator, and its working process is based on the input signal to output a signal of a corresponding frequency, and the difference lies in the different input signals, that is, the output signals of the closed-loop control branch and the open-loop control branch are different. For the convenience of description, the embodiment of the present application first takes the oscillator 31 as an example of a voltage-controlled oscillator, that is, the output signal of the closed-loop control branch is a first voltage signal, and the output signal of the open-loop control branch is a second voltage signal.

[0070] In some embodiments, since the desired frequency of the oscillator output signal needs to be adjusted by adjusting the target digital codeword during the modulation process of the frequency source system, the frequency source system needs to determine the target digital codeword according to the desired frequency of the oscillator output signal.

[0071] Exemplarily, when the signal modulation is a uniform scanning frequency, for example, within 1 second, with 100 MHz as the starting frequency, the frequency increases by 0.1 MHz every 0.01 second (sweeping at a slope of 10 MHz / s), it is necessary to complete a continuous frequency modulation scan of 100 frequency points within 100-110 MHz within 1 second.

[0072] Then for each frequency point, it is necessary to determine the digital code word corresponding to each frequency point, so that the open-loop control branch outputs a second voltage signal to the oscillator according to the digital code word, and the closed-loop control branch outputs a first voltage signal to the oscillator according to the reference frequency, so that the oscillator can output the frequency corresponding to the frequency point.

[0073] As a feasible implementation method, a first storage module can be set in the open-loop control branch to store the correspondence between multiple digital codewords and the frequency points corresponding to each digital codeword. In this way, when it is necessary to output the frequency corresponding to the target frequency point, the target frequency point can be sent to the first storage module, so that the first storage module can find the target digital codeword corresponding to the target frequency point from the multiple data codewords in the corresponding relationship based on the target frequency point.

[0074] Since the signal that can be processed and calculated is a digital signal, and the signal required by the oscillator is a voltage signal, the open-loop control branch can also include a digital-to-analog converter. The digital-to-analog converter is used to receive the target digital codeword output by the first storage module and output a second voltage signal corresponding to the target digital codeword to the oscillator.

[0075] For details, please refer to Figure 4 In the frequency source system provided in the embodiment of the present application, the open-loop control branch 33 includes: a first storage module 331 and a digital-to-analog converter 332 .

[0076] like Figure 4As shown, the first input terminal 331-1 of the first storage module 331 is used to receive the frequency point (target frequency point) corresponding to the target digital codeword, the second input terminal 331-2 of the first storage module 331 is connected to the calibration branch 34 to receive calibration information, and the output terminal 331-3 of the first storage module 331 is connected to the input terminal 332-1 of the digital-to-analog converter 332.

[0077] The output terminal 332-2 of the digital-to-analog converter 332 is connected to the second input terminal 31-3 of the oscillator 31; the digital-to-analog converter 332 is used to receive the target digital codeword output by the first storage module, and output a second voltage signal corresponding to the target digital codeword to the oscillator.

[0078] It is understandable that since the lookup table is a data structure, it can be implemented in a variety of ways such as an array, a hash table, a memory-mapped file, etc., and can quickly find the output value through the input value, especially when the data has been pre-calculated and stored in the memory. Therefore, as a feasible implementation method, the first storage module 331 can be specifically a lookup table (also referred to as a Vctrl lookup table). In order to improve the speed of determining the target digital codeword during the signal modulation process, thereby improving the signal modulation speed.

[0079] As a feasible implementation method, Figure 4 As shown, the frequency source system further includes: a waveform generator 35. The waveform generator 35 is connected to the first input terminal 331-1 of the first storage module 331, and is used to output the frequency point corresponding to the target digital codeword to the first storage module 331. The waveform generator 35 can output the frequency point corresponding to the target digital codeword to the first storage module according to the expected frequency of the signal output by the oscillator, so that the first storage module 331 outputs a second voltage signal to the oscillator 31 based on the frequency point, so that the oscillator can output the signal of the expected frequency.

[0080] As a way to achieve this, Figure 4 As shown, the waveform generator 35 can also send a signal to the frequency divider ( Figure 4 The frequency divider (not shown) outputs a frequency division ratio, so that the frequency divider divides the output frequency of the oscillator 31 according to the frequency division ratio to obtain a feedback frequency.

[0081] It can be seen that the open-loop control branch provided in this embodiment includes a first storage module for storing the correspondence between multiple digital codewords and the frequency point corresponding to each digital codeword, and a digital-to-analog converter for converting the digital codeword into a second voltage signal. When performing signal modulation, the target digital codeword can be quickly determined and converted into a second voltage signal based on the frequency point corresponding to the desired frequency output by the frequency source system, so as to quickly adjust the output frequency of the oscillator.

[0082] In some embodiments, since the initial correspondence stored in the first storage module 331 may not take into account the frequency modulation error, or due to changes in environmental factors, the initial correspondence may be inaccurate, resulting in the oscillator being unable to reach the desired frequency based on the second voltage signal provided by the open-loop control branch. Therefore, it is necessary to calibrate the initial correspondence stored in the first storage module 331 based on the calibration information provided by the calibration branch.

[0083] As a feasible implementation method, please continue to refer to Figure 4 In the frequency source system provided in the embodiment of the present application, the calibration branch 34 includes: a calibration module 341, a second storage module 342 and an analog-to-digital converter 343.

[0084] like Figure 4 As shown, the input end 343-1 of the analog-to-digital converter 343 is connected to the first end 32-1 of the closed-loop control branch 32, and the output end 343-2 of the analog-to-digital converter 343 is connected to the input end 342-1 of the second storage module 342. The input end 341-1 of the calibration module 341 is connected to the output end 342-2 of the second storage module 342, and the output end 341-2 of the calibration module 341 (i.e., the output end of the calibration branch) is connected to the second input end 331-2 of the first storage module 331.

[0085] The analog-to-digital converter 343 is used to convert the voltage signal into a digital signal. Specifically, the analog-to-digital converter 343 is used to obtain the first voltage signal from the first end 32 - 1 of the closed-loop control branch 32 , and store the digital codeword corresponding to the first voltage signal into the second storage module 342 .

[0086] The calibration module 341 is used to calibrate the target digital codeword in the first storage module based on the digital codeword corresponding to the first voltage signal stored in the second storage module 342 and the gain relationship between the closed-loop control branch and the open-loop control branch.

[0087] It is understandable that the digital codeword corresponding to the first voltage signal stored in the second storage module 342 can be used to determine the fluctuation of the first voltage signal, that is, the error of the frequency source system during the frequency modulation process. In the embodiment of the present application, in order to prevent the first voltage signal from fluctuating, the target digital codeword in the open-loop control branch is adjusted based on the fluctuation of the first voltage signal, and then the second voltage signal is adjusted so that the second voltage signal compensates for the error in the frequency modulation process.

[0088] However, there is a certain gain relationship between the closed-loop control branch and the open-loop control branch. Gain usually refers to the degree to which a signal is amplified during transmission and is an important parameter for measuring the signal amplification capability. For example, for every 1Hz increase in the first voltage represented by the first voltage signal, the output frequency of the voltage-controlled oscillator will increase by 1V, while the second voltage represented by the second voltage signal needs to increase by 2Hz to increase the output frequency of the voltage-controlled oscillator by 1V.

[0089] Therefore, when determining the calibration information, it is necessary to consider not only the fluctuation of the first voltage signal but also the gain relationship between the closed-loop control branch and the open-loop control branch.

[0090] Specifically, the gain relationship between the closed-loop control branch and the open-loop control branch can be determined based on the relationship between the gain of the open-loop control branch and the gain of the closed-loop control branch. For example, the gain of the open-loop control branch is compared with the gain of the closed-loop control branch, and the obtained ratio K is used as the gain relationship between the closed-loop control branch and the open-loop control branch.

[0091] It should be understood that the gain of a circuit is related to the design of the circuit and the performance of the circuit elements. For example, the topology of the circuit determines the transmission path and mode of the signal in the circuit, which directly affects the size and stability of the gain; high-precision, high-stability components can ensure the accuracy and stability of the circuit gain. In the process of actual application, the gain of the open-loop control branch and the closed-loop control branch can be calculated by the designed transfer function, or determined by experimental measurement, and the embodiments of the present application are not limited to this.

[0092] The solution provided in this embodiment converts the first voltage signal into a digital codeword through an analog-to-digital converter and stores it in the second storage module, and then the calibration module can determine the fluctuation of the first voltage signal that can characterize the modulation error based on the digital codeword corresponding to the first voltage signal stored in the second storage module. Then, the calibration information is determined in combination with the gain relationship between the closed-loop control branch and the open-loop control branch, so that the calibration information can compensate for the modulation error. Then, the oscillator can directly reach the desired frequency based on the calibrated second voltage signal, while avoiding voltage fluctuations in the closed-loop control branch. This helps to improve the stability and modulation speed of the system, ensure that the system can remain stable under various working conditions, and avoid voltage fluctuations in the closed-loop control branch that lead to a reduction in modulation speed.

[0093] In some embodiments, since the purpose of calibration is to prevent the first voltage signal from fluctuating, during the calibration process, the target digital codeword can be calibrated based on the fluctuation of the first voltage signal and the gain relationship between the closed-loop control branch and the open-loop control branch.

[0094] As a feasible implementation method, the calibrated target digital codeword satisfies the following relationship: V2[n]=V2'[n]+k×(V1[n]- V1[0]).

[0095] Among them, n is used to represent the frequency point corresponding to the target digital codeword; V2[n] is the target digital codeword after calibration; V2'[n] is the target digital codeword before calibration; V1[n] is the digital codeword corresponding to the first voltage signal obtained from the first end of the closed-loop control branch at the nth frequency point; V1[0] is the starting codeword; k is the gain coefficient of the open-loop control branch compared to the closed-loop control branch.

[0096] It can be understood that V1[0] is the digital code corresponding to the starting voltage of the closed-loop control branch at the initial frequency of the swept frequency modulation, and V1[n]- V1[0] can be used to represent the fluctuation of the first voltage signal at the current frequency relative to the starting voltage. Based on the fluctuation of the first voltage signal and the gain coefficient of the open-loop control branch compared to the closed-loop control branch, the calibration code is determined to be k×(V1[n]-V1[0]).

[0097] The calibration codeword can be used to represent the deviation of the output frequency of the oscillator caused by the fluctuation of the first voltage signal and the gain relationship between the closed-loop control branch and the open-loop control branch. Therefore, the calibrated target digital codeword can be made the target digital codeword plus the calibration codeword, so that the open-loop control branch outputs a higher second voltage signal based on the calibration codeword to correct the above deviation.

[0098] It can be seen from the above embodiments that the scheme provided by the embodiments of the present application determines the calibration codeword based on the fluctuation of the first voltage signal and the gain coefficient of the open-loop control branch compared to the closed-loop control branch. Since the fluctuation of the first voltage signal is generated based on the frequency modulation error of the frequency source system, the calibration codeword determined based on the fluctuation of the first voltage signal can be used to characterize the error of frequency modulation using an uncalibrated target digital codeword. And the gain coefficient of the open-loop control branch compared to the closed-loop control branch can be used to characterize the influence of the degree of change of the two voltage signals on the output frequency. Therefore, by calibrating the target digital codeword through the calibration codeword, the second voltage signal output by the open-loop control branch can be used to correct the deviation, so that the first voltage information in the closed-loop control branch does not fluctuate, thereby improving the modulation speed of the frequency source system.

[0099] In some embodiments, since the calibration branch in the above embodiment calibrates the digital codeword in the first storage module, it needs to be performed during the frequency sweep modulation, and when the open-loop control branch outputs the second voltage signal corresponding to the target frequency, the first voltage signal of the closed-loop control branch at the target frequency is obtained. That is, the above calibration process is calibrated based on the actual operation of the circuit.

[0100] Therefore, as a feasible implementation method, the operation phase of the frequency source system in this embodiment can be divided into a calibration phase and a working phase. In the calibration phase, the calibration branch is turned on, so that the calibration branch can update the digital codeword in the first storage module; in the working phase of the frequency source system, the calibration branch is cut off, and the open-loop control branch outputs the second voltage signal based on the calibrated digital codeword in the first storage module.

[0101] It is understandable that since different targets may have different reflection characteristics for different frequencies, frequency source systems usually require frequency sweep modulation so that the radar can detect at multiple frequencies and find the frequency that is most suitable for detecting a specific target.

[0102] Therefore, as a feasible implementation method, during the calibration phase, the frequency source system can be made to continuously output frequencies within a certain frequency range to achieve continuous frequency modulation scanning. For example, within 1 second, with 100MHz as the starting frequency, the frequency increases by 0.1MHz every 0.01s (sweeping at a slope of 10MHz / s), then it is necessary to complete continuous frequency modulation scanning for 100 frequency points within 100~110MHz within 1s.

[0103] It is understandable that when the environmental factors of the frequency source system change, the output frequency of the oscillator will also have a certain deviation. Therefore, when the environmental parameters such as the device temperature change, the frequency source system can be controlled to enter the calibration phase to achieve the calibration of the target digital codeword.

[0104] In some embodiments, in combination Figure 4 , see Figure 5 , Figure 5 The overall structure diagram of a frequency source system provided in an embodiment of the present application is shown in FIG. The frequency source system includes: an oscillator 31 , a closed-loop control branch 32 , an open-loop control branch 33 , a calibration branch 34 and a waveform generator 35 .

[0105] like Figure 5 As shown, the closed-loop control branch 32 includes a frequency detector 321, a loop filter 322 and a frequency divider 323; the open-loop control branch 33 includes a first storage module 331 and a digital-to-analog converter 332; and the calibration branch 34 includes a calibration module 341, a second storage module 342 and an analog-to-digital converter 343.

[0106] In other embodiments, since the read and write speed of the storage module will affect the modulation speed of the frequency source system, in order to improve the modulation speed, the storage module may not be set in the frequency source system, and the open-loop control branch may directly receive the target digital codeword to generate the second voltage signal.

[0107] For details, please refer to Figure 6 In the frequency source system provided in the embodiment of the present application, the open-loop control branch 33 may include: a digital-to-analog converter 333 .

[0108] like Figure 6 As shown, the first input terminal 333-1 of the digital-to-analog converter 333 is used to receive the target digital codeword, and the output terminal 333-2 of the digital-to-analog converter 333 is connected to the second input terminal 31-3 of the oscillator. The digital-to-analog converter 333 is used to output a second voltage signal to the oscillator based on the target digital codeword.

[0109] It is understandable that the target digital codeword may be a control device (such as a controller or Figure 6 The control device can determine the target digital codeword based on the desired frequency of the oscillator and send it to the digital-to-analog converter.

[0110] Specifically, as a feasible implementation method, Figure 6 As shown, the frequency source system further includes: a waveform generator 35 . The waveform generator 35 is connected to the first input terminal 333 - 1 of the digital-to-analog converter 333 ; the waveform generator 35 is used to output a target digital codeword to the digital-to-analog converter 333 .

[0111] Exemplarily, when the frequency source system takes 100 MHz as the starting frequency and sweeps the frequency at a slope of 10 MHz / s, the desired frequency of the oscillator is 100 MHz as the starting frequency, and the frequency increases by 0.1 MHz every 0.01 s. In this way, the control device can determine the initial digital codeword corresponding to 100 MHz and the digital codeword corresponding to each increased 0.1 MHz according to the corresponding relationship between the desired frequency and the digital codeword. Then the waveform generator takes the initial digital codeword as the starting point, increases the digital codeword corresponding to 0.1 MHz every 0.01 s, and sends it to the digital-to-analog converter 333. The digital-to-analog converter 333 converts the received digital codeword into an analog voltage signal (a second voltage signal) and outputs it to the oscillator.

[0112] Since the target digital codeword is determined directly based on the expected frequency, circuit design deviations, etc. are not taken into account. Therefore, please continue to refer to Figure 6 In this embodiment, the second input terminal 333-3 of the digital-to-analog converter 333 is connected to the calibration branch 34 to receive calibration information, and the digital-to-analog converter 333 is used to output a second voltage signal to the oscillator 31 based on the target digital codeword and the calibration information.

[0113] It can be understood that the calibration information is used to calibrate the target digital codeword, so the digital-to-analog converter 333 can be specifically used to calibrate the target digital codeword based on the calibration information, and then output the second voltage signal to the oscillator based on the calibrated target digital codeword.

[0114] It can be seen that in the solution provided by this embodiment, the open-loop control branch only includes a digital-to-analog converter, and the digital-to-analog converter outputs a second voltage signal to the oscillator based on the received digital codeword and calibration information. Since the received digital codeword and calibration information are directly converted into analog signals by the digital-to-analog converter, the step of reading the target digital codeword from the storage module is avoided, thereby significantly reducing the delay in the control process, thereby improving the overall performance and response speed of the system.

[0115] In some embodiments, when the waveform generator outputs the target digital codeword to the digital-to-analog converter, the frequency modulation error is not taken into account, resulting in the oscillator being unable to reach the desired frequency based on the second voltage signal provided by the open-loop control branch. Therefore, the target digital codeword needs to be calibrated based on the calibration information provided by the calibration branch.

[0116] As a feasible implementation method, please continue to refer to Figure 6 The calibration branch 34 provided in the embodiment of the present application may include: an analog-to-digital converter 344 and a calibration module 345 .

[0117] like Figure 6 As shown, the input terminal 344-1 of the analog-to-digital converter 344 is connected to the first terminal 32-1 of the closed-loop control branch 32, and the output terminal 344-2 of the analog-to-digital converter 344 is connected to the input terminal 345-1 of the calibration module 345; the analog-to-digital converter 344 is used to obtain a first voltage signal from the first terminal of the closed-loop control branch 32, and output a digital codeword corresponding to the first voltage signal to the calibration module 345.

[0118] The output terminal 345-2 of the calibration module 345 is connected to the second input terminal 333-3 of the digital-to-analog converter; the calibration module 345 is used to determine the calibration codeword based on the digital codeword corresponding to the first voltage signal obtained in the first clock cycle and the digital codeword corresponding to the first voltage signal obtained in the second clock cycle, and output the calibration codeword as calibration information to the digital-to-analog converter 333; the first clock cycle and the second clock cycle are two adjacent times before the current clock cycle.

[0119] It is understandable that, due to the processing speed limitation of the internal circuit and algorithm when the calibration module receives and processes the calibration signal, a certain processing delay will be generated. And due to the physical characteristics of the transmission medium (such as resistance, capacitance, inductance, etc.) and the influence of the transmission distance, a certain transmission delay will be generated. That is, there will be a certain delay when the calibration branch is calibrated. Therefore, it is necessary to calibrate the second voltage signal of the current clock cycle based on the clock cycle before the current time.

[0120] It should be noted that the time in the embodiments of the present application is not a time unit such as seconds, minutes, hours, etc. in the traditional sense, but a discrete time variable controlled by a clock inside the system. This clock performs reverse switching at a fixed frequency, and the time variable i increases by 1 every time a complete switching cycle is completed.

[0121] For example, the clock performs "010101" inversion switching at a fixed frequency, and the time increases by one each time a switching is completed. The inversion switching of "010101" constitutes a periodic cycle of the clock. At the end of each cycle, the time variable i increases by 1. The length of this cycle (i.e., the time required to complete a "01" switching) is the inverse of the clock frequency.

[0122] Based on this, the digital codeword corresponding to the first clock cycle is the digital codeword corresponding to the first voltage signal in the period corresponding to the first clock cycle; the digital codeword corresponding to the second clock cycle is the digital codeword corresponding to the first voltage signal in the period corresponding to the second clock cycle. Since the first clock cycle and the second clock cycle are two adjacent times, the digital codeword corresponding to the first clock cycle and the digital codeword corresponding to the second clock cycle can be used to measure the fluctuation of the first voltage signal.

[0123] A calibration code is then determined based on the fluctuation of the first voltage signal, and the calibration code is output to the digital-to-analog converter as calibration information, so that the digital-to-analog converter outputs a second voltage signal to the oscillator based on the target digital code and the calibration code.

[0124] When the target digital codeword and the calibration codeword are input into the DAC, they jointly determine the output analog voltage value. This voltage value is precisely controlled and adjusted by the circuit elements inside the DAC (such as analog electronic switches, bit weight networks, summing operational amplifiers, etc.).

[0125] It can be understood that since the calibration codeword can be used to characterize the frequency modulation deviation of the frequency source system, it is input into the digital-to-analog converter so that the frequency generated by the oscillator based on the second voltage signal can compensate for the deviation and reach the expected frequency corresponding to the target digital codeword, thereby improving the accuracy and stability of the frequency output of the frequency source system.

[0126] It can be seen that the calibration scheme provided in this embodiment is a real-time calibration, that is, the second voltage signal is directly adjusted based on the fluctuation of the first voltage signal at a historical moment. Therefore, as a feasible implementation method, the frequency source system provided in this embodiment has the calibration branch turned on during the working phase of the frequency source system. That is, the calibration branch can perform the above calibration at the same time as each frequency sweep modulation.

[0127] In some embodiments, due to the presence of various nonlinearities, drifts, or noise factors in the actual system, which may cause the gains of the closed-loop and open-loop control branches to not fully match, a calibration codeword is also needed to compensate for this deviation so that the gains of the closed-loop control branch and the open-loop control branch match, thereby enabling the open-loop control branch to accurately compensate for the frequency modulation error based on the calibration information.

[0128] As a feasible implementation method, the calibration module is specifically used to determine the calibration codeword based on the digital codeword corresponding to the first voltage obtained in the first clock cycle, the digital codeword corresponding to the first voltage obtained in the second clock cycle, and the gain relationship between the closed-loop control branch and the open-loop control branch.

[0129] The calibration module 345 performs calibration through the gain relationship between the closed-loop control branch and the open-loop control branch, thereby achieving accurate gain matching and obtaining a calibration codeword that can compensate for the system deviation caused by the gain mismatch.

[0130] Since the target digital codeword is a digital codeword corresponding to the desired frequency of the oscillator provided by the waveform generator, the calibration codeword can be used to compensate for the system deviation. Therefore, the digital-to-analog converter 333 outputs a second voltage signal to the oscillator based on the target digital codeword and the calibration codeword, so that the frequency generated by the oscillator based on the second voltage signal can compensate for the deviation and reach the desired frequency corresponding to the target digital codeword, thereby improving the accuracy and stability of the frequency output.

[0131] Specifically, the calibration module can measure the fluctuation of the first voltage through the digital codeword corresponding to the first clock cycle and the digital codeword corresponding to the second clock cycle, and then determine the calibration codeword based on the fluctuation of the first voltage and the gain relationship between the closed-loop control branch and the open-loop control branch.

[0132] As a feasible implementation method, the calibration codeword can be expressed by the following relationship: V2[i]=k×(V1[i-1]-V1[i-2]).

[0133] Among them, i is used to represent the current time; V2[i] is used to represent the calibration codeword corresponding to the current clock cycle i; k is the gain coefficient of the open-loop control branch compared to the closed-loop control branch; V1[i-1] is used to represent the digital codeword corresponding to the first clock cycle; V1[i-2] is used to represent the digital codeword corresponding to the second clock cycle.

[0134] It is understandable that the calibration module needs a certain amount of calculation time when calculating the calibration codeword, so during calibration, it may not be possible to accurately determine the calibration codeword corresponding to the current time i based on the digital codewords corresponding to the time i-1 and time i-2.

[0135] As another feasible implementation manner, the calibration codeword can be expressed by the following relationship: V2[i]=k×(V1[i-1-d]- V1[i-2-d]).

[0136] Wherein, d is used to represent the delay of the calibration module. In practical applications, the delay of the calibration module can be determined according to the specific design of the circuit and the performance of the calibration module, and the embodiments of the present application do not limit this.

[0137] It can be seen that the frequency source system provided in this embodiment measures the real-time fluctuation of the first voltage through the digital codeword corresponding to the first clock cycle and the digital codeword corresponding to the second clock cycle. It can be understood that the fluctuation can be used to characterize the deviation between the output frequency of the frequency source system and the desired frequency. Therefore, the scheme of the present application is based on the fluctuation and the gain relationship between the closed-loop control branch and the open-loop control branch to determine the calibration codeword. Then, the target digital codeword is calibrated by the calibration codeword, so that the open-loop control branch corrects the frequency modulation deviation of the frequency source system, thereby avoiding the closed-loop control branch to correct the deviation and generate fluctuations, thereby being able to improve the response speed of the closed-loop control branch, and thereby improve the modulation speed of the frequency source system.

[0138] In some embodiments, in combination Figure 6 , see Figure 7 , Figure 7 The overall structure diagram of another frequency source system provided in the embodiment of the present application is as follows. The frequency source system comprises: an oscillator 31 , a closed-loop control branch 32 , an open-loop control branch 33 , a calibration branch 34 and a waveform generator 35 .

[0139] like Figure 7 As shown, the closed-loop control branch 32 includes a frequency detector 321 , a loop filter 322 and a frequency divider 323 ; the open-loop control branch 33 includes a digital-to-analog converter 333 ; and the calibration branch 34 includes a calibration module 345 and an analog-to-digital converter 344 .

[0140] In other embodiments, the oscillator in the frequency source system may be a digitally controlled oscillator, which generates a signal of a corresponding frequency by receiving a digital signal and according to the size of the digital codeword of the digital signal, that is, both the open-loop control branch and the closed-loop control branch output digital codewords.

[0141] Therefore, as a feasible implementation method, when the oscillator is a digitally controlled oscillator, the closed-loop control branch may further include an analog-to-digital converter for converting the first voltage signal into a first digital signal and inputting the first digital signal into the digitally controlled oscillator.

[0142] Moreover, in the case where the oscillator is a digitally controlled oscillator, the digital-to-analog converter and analog-to-digital converter used for converting digital signals and voltage signals into each other in the above embodiments can be adjusted or deleted according to actual conditions, and the embodiments of the present application will not be repeated here.

[0143] For example, as a feasible implementation method, when the oscillator is a digitally controlled oscillator, the system structure of the frequency source system provided in the embodiment of the present application can be as follows: Figure 8 That is, the frequency source system includes: an oscillator 31 , a closed-loop control branch 32 , an open-loop control branch 33 , a calibration branch 34 and a waveform generator 35 .

[0144] The closed-loop control branch 32 includes a phase frequency detector 321, a loop filter 322, a frequency divider 323 and a digital-to-analog converter 324. The functions of the phase frequency detector 321, the loop filter 322 and the frequency divider 323 can be referred to in the above embodiment. The digital-to-analog converter 324 is used to convert the first voltage signal filtered by the loop filter 322 into a first digital signal and output it to the oscillator 31.

[0145] The open-loop control branch 33 includes a first storage module 331 ; the first storage module 331 is used to determine the corresponding target digital codeword based on the target frequency sent by the waveform generator, and generate a second digital signal based on the target digital codeword and output it to the oscillator 31 .

[0146] The calibration branch 34 includes a calibration module 341 and a second storage module 342; the second storage module 342 can store the target frequency point and the first digital signal in correspondence, and the function of the calibration module 341 can refer to the above embodiment.

[0147] An embodiment of the present application also provides a radar, which includes a radio frequency transceiver system and a frequency source system provided by any of the above embodiments; wherein the radio frequency transceiver system is connected to the frequency source system, and the frequency source system is used to provide different frequencies for the radio frequency transceiver system.

[0148] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of the system. In order to achieve the above functions, the frequency source system includes hardware structures and / or software modules corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0149] Corresponding to the above-mentioned frequency source system, an embodiment of the present application provides a frequency modulation method for a frequency source system, and the frequency modulation method can be applied to the calibration branch in the frequency source system provided in any of the above-mentioned embodiments. Or it can be understood that the above-mentioned frequency source system is an exemplary division of functional modules of the frequency source system according to the frequency modulation method introduced below in the embodiment of the present application. That is to say, the division of modules in the embodiment of the present application according to the frequency modulation method introduced below is schematic, which is only a logical function division. There may be other division methods in actual implementation, which will not be described in detail herein. Based on the frequency modulation method introduced below, it can be known that the modules integrated in the above-mentioned frequency source system can be implemented in the form of hardware or in the form of software functional modules.

[0150] The frequency modulation method of the frequency source system provided in the embodiment of the present application includes: acquiring a first signal in a closed-loop control branch; and adjusting a second signal output by the open-loop control branch based on the first signal to adjust the output frequency of the oscillator.

[0151] The calibration branch in the frequency source system is connected to the closed-loop control branch and the open-loop control branch. The calibration branch can obtain a first signal in the closed-loop control branch and adjust a second signal output by the open-loop control branch based on the first signal, so that the open-loop control branch adjusts the output frequency of the oscillator based on the adjusted second signal.

[0152] In some embodiments, adjusting the second signal output by the open-loop control branch based on the first signal includes: adjusting the second signal output by the open-loop control branch based on fluctuations of the first signal.

[0153] Furthermore, as a feasible implementation method, the second signal output by the open-loop control branch is adjusted based on the fluctuation of the first signal, including: providing calibration information to the open-loop control branch based on the fluctuation of the first signal and the gain relationship between the closed-loop control branch and the open-loop control branch; so that the open-loop control branch adjusts the output second signal based on the calibration information.

[0154] In some embodiments, when the open-loop control branch outputs the second signal based on the digital codeword stored in the open-loop control branch, the calibration branch needs to calibrate the digital codeword stored in the open-loop control branch.

[0155] Based on this, as a specific implementation method, obtaining the first signal in the closed-loop control branch specifically includes: obtaining and storing the first signal corresponding to each frequency point. Adjusting the second signal output by the open-loop control branch based on the fluctuation of the first signal includes: determining the fluctuation value corresponding to each frequency point based on the stored first signal corresponding to each frequency point and the initial first signal; and adjusting the digital codeword corresponding to each frequency point in the open-loop control branch based on the fluctuation value corresponding to each frequency point.

[0156] That is, for each frequency point, the fluctuation value of the first signal is determined based on the first signal corresponding to the current frequency point and the initial first signal, and then the digital codeword corresponding to the frequency point in the open-loop control branch is adjusted based on the fluctuation value of the first signal to obtain the calibrated target digital codeword.

[0157] Specifically, as a feasible implementation method, the calibrated target digital codeword satisfies the following relationship:

[0158] V2[n]=V2'[n]+k×(V1[n]- V1[0]);

[0159] Among them, n is used to represent the current frequency point; V2[n] is the target digital codeword after calibration; V2'[n] is the target digital codeword before calibration; V1[n] is the first signal corresponding to the nth frequency point; V1[0] is the starting first signal; k is the gain coefficient of the open-loop control branch compared to the closed-loop control branch.

[0160] In other embodiments, when the open-loop control branch outputs the second signal based on the digital codeword sent by the divider, the calibration branch needs to determine the fluctuation of the first signal in real time, and then adjust the digital codeword of the open-loop control branch in real time according to the fluctuation of the first signal.

[0161] Based on this, as a specific implementation method, obtaining the first signal in the closed-loop control branch specifically includes: obtaining the first signal corresponding to the first clock cycle and the first signal corresponding to the second clock cycle, wherein the first clock cycle and the second clock cycle are two adjacent clock cycles before the current clock cycle.

[0162] It should be understood that when the calibration branch performs real-time calibration, due to calculation delay, the fluctuation of the first signal cannot be calculated based on the first signal of the current clock cycle, and therefore needs to be calculated based on two adjacent clock cycles before the current clock cycle.

[0163] Furthermore, the second signal output by the open-loop control branch is adjusted based on the fluctuation of the first signal, including: determining the fluctuation value of the first signal based on the first signal corresponding to the first clock cycle and the first signal corresponding to the second clock cycle; adjusting the digital codeword of the current clock cycle in the open-loop control branch based on the fluctuation value of the first signal to adjust the second signal output by the open-loop control branch.

[0164] That is, the solution provided in this embodiment adjusts the target digital codeword of the current clock cycle based on the fluctuation of the first signal generated in the previous period of time to obtain a calibrated target digital codeword.

[0165] Since the gain coefficient of the open-loop control branch compared to the closed-loop control branch needs to be considered when calibrating the target digital codeword, specifically, as a feasible implementation method, the calibration codeword corresponding to the current clock cycle satisfies the following relationship:

[0166] V2[i]=k×(V1[i-1-d]- V1[i-2-d]).

[0167] Among them, i is used to represent the current clock cycle; V2[i] is used to represent the calibration codeword corresponding to the current clock cycle i; k is the gain coefficient of the open-loop control branch compared to the closed-loop control branch; V1[i-1] is used to represent the digital codeword corresponding to the first clock cycle; V1[i-2] is used to represent the digital codeword corresponding to the second clock cycle; d is used to represent the delay of the calibration module.

[0168] Based on the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0169] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0170] The units described as separate components may or may not be physically separated, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0171] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0172] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a device or processor to execute all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, ROM, RAM, disk or CD-ROM and other media that can store program code.

[0173] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application 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 frequency source system, characterized in that: include: An oscillator, a closed-loop control branch, an open-loop control branch, and a calibration branch; The oscillator is used to output a signal of corresponding frequency based on the first signal output by the closed-loop control branch and the second signal output by the open-loop control branch; A first end of the closed-loop control branch is connected to a first input end of the oscillator, a second end of the closed-loop control branch is connected to an output end of the oscillator, and the closed-loop control branch is used to output a first signal to the oscillator based on a reference frequency and a frequency of a signal output by the oscillator; The open-loop control branch is connected to the second input terminal of the oscillator, and the open-loop control branch is used to output a second signal to the oscillator based on a target digital codeword, wherein the target digital codeword corresponds to a desired frequency of a signal output by the oscillator; The calibration branch is connected to the first end of the closed-loop control branch and is also connected to the open-loop control branch, the calibration branch is used to provide calibration information to the open-loop control branch based on the fluctuation of the first signal, and the calibration information is used to calibrate the target digital codeword; The open-loop control branch is configured to: calibrate the target digital codeword based on the calibration information to obtain a calibrated target digital codeword, and output a second signal to the oscillator based on the calibrated target digital codeword.

2. The frequency source system according to claim 1, characterized in that: The oscillator is a voltage-controlled oscillator, the first signal is a first voltage signal, and the second signal is a second voltage signal; or, The oscillator is a digitally controlled oscillator, the first signal is a first digital signal, and the second signal is a second digital signal.

3. The frequency source system according to claim 2, characterized in that: In the case where the oscillator is a voltage-controlled oscillator, the open-loop control branch includes: a first storage module and a digital-to-analog converter; The first input end of the first storage module is used to receive the target frequency point corresponding to the expected frequency, the second input end of the first storage module is connected to the calibration branch to receive the calibration information, and the output end of the first storage module is connected to the input end of the digital-to-analog converter; The first storage module stores a correspondence between digital codewords and frequency points; the first storage module is used to find the target digital codeword from a plurality of data codewords in the correspondence relationship based on the target frequency point, and output it to the digital-to-analog converter; The output end of the digital-to-analog converter is connected to the second input end of the oscillator; the digital-to-analog converter is used to receive the target digital codeword output by the first storage module, and output a second voltage signal corresponding to the target digital codeword to the oscillator.

4. The frequency source system according to claim 3, characterized in that: The calibration branch includes: a calibration module, a second storage module and an analog-to-digital converter; The input end of the analog-to-digital converter is connected to the first end of the closed-loop control branch, and the output end of the analog-to-digital converter is connected to the input end of the second storage module; the analog-to-digital converter is used to obtain a first voltage signal from the first end of the closed-loop control branch, and store a digital code word corresponding to the first voltage signal in the second storage module; The input end of the calibration module is connected to the output end of the second storage module, and the output end of the calibration module is connected to the second input end of the first storage module; the calibration module is used to calibrate the target digital codeword in the first storage module based on the digital codeword corresponding to the first voltage signal stored in the second storage module and the gain relationship between the closed-loop control branch and the open-loop control branch.

5. The frequency source system according to claim 4, characterized in that: The calibrated target digital codeword satisfies the following relationship: V2[n]=V2'[n]+k×(V1[n]- V1[0]); The frequency point corresponding to the target digital codeword is the nth frequency point; V2[n] is the target digital codeword after calibration; V2'[n] is the target digital codeword before calibration; V1[n] is the digital codeword corresponding to the first voltage signal obtained from the first end of the closed-loop control branch at the nth frequency point; V1[0] is the starting codeword; k is the gain coefficient of the open-loop control branch compared to the closed-loop control branch.

6. The frequency source system according to claim 2, characterized in that: In the case where the oscillator is a voltage-controlled oscillator, the open-loop control branch includes: a digital-to-analog converter; The first input terminal of the digital-to-analog converter is used to receive the target digital codeword, the second input terminal of the digital-to-analog converter is connected to the calibration branch to receive the calibration information, and the output terminal of the digital-to-analog converter is connected to the second input terminal of the oscillator; The digital-to-analog converter is used to output a second voltage signal to the oscillator based on the target digital codeword and the calibration information.

7. The frequency source system according to claim 6, characterized in that: The calibration branch includes: an analog-to-digital converter and a calibration module; The input end of the analog-to-digital converter is connected to the first end of the closed-loop control branch, and the output end of the analog-to-digital converter is connected to the input end of the calibration module; the analog-to-digital converter is used to obtain a first voltage signal from the first end of the closed-loop control branch, and output a digital code word corresponding to the first voltage signal to the calibration module; The output end of the calibration module is connected to the second input end of the digital-to-analog converter; the calibration module is used to determine a calibration codeword based on a digital codeword corresponding to the first voltage signal in a first clock cycle and a digital codeword corresponding to the first voltage signal in a second clock cycle, and output the calibration codeword as the calibration information to the digital-to-analog converter; the first clock cycle and the second clock cycle are before the current clock cycle, and the first clock cycle and the second clock cycle are two adjacent clock cycles; The digital-to-analog converter is further configured to output a second voltage signal to the oscillator based on the target digital codeword and the calibration codeword.

8. The frequency source system according to claim 7, characterized in that: The calibration module is specifically used to determine the calibration codeword based on the digital codeword corresponding to the first voltage signal obtained in the first clock cycle, the digital codeword corresponding to the first voltage signal obtained in the second clock cycle, and the gain relationship between the closed-loop control branch and the open-loop control branch.

9. A frequency modulation method for a frequency source system, characterized in that: The frequency source system is the frequency source system according to any one of claims 1 to 8, and the frequency modulation method comprises: Acquiring a first signal in the closed-loop control branch; The second signal output by the open-loop control branch is adjusted based on the fluctuation of the first signal to adjust the output frequency of the oscillator.

10. The frequency modulation method according to claim 9, characterized in that: The adjusting the second signal output by the open-loop control branch based on the fluctuation of the first signal includes: Based on the fluctuation of the first signal and the gain relationship between the closed-loop control branch and the open-loop control branch, calibration information is provided to the open-loop control branch, so that the open-loop control branch adjusts the output second signal based on the calibration information.

11. A radar, characterized in that: The radar comprises a radio frequency transceiver system and a frequency source system as described in any one of claims 1 to 8; The radio frequency transceiver system is connected to the frequency source system, and the frequency source system is used to provide different frequencies for the radio frequency transceiver system.

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