CN112383306A - Atomic clock frequency control method and equipment - Google Patents
Atomic clock frequency control method and equipment Download PDFInfo
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Abstract
The embodiment of the invention provides a method and equipment for controlling the frequency of an atomic clock. The method comprises the following steps: scanning direct current of a laser, performing peak value search on a received Doppler absorption spectrum line signal to obtain laser fundamental frequency current, loading a modulation signal on the laser fundamental frequency current to obtain a laser fundamental frequency error signal, adjusting the laser fundamental frequency, and locking the laser fundamental frequency; scanning the microwave frequency signal to obtain a CPT resonance spectral line, performing peak value search on the CPT resonance spectral line to obtain a central frequency, performing 2FSK modulation on the central frequency to obtain a microwave 2FSK modulation signal, then demodulating the laser fundamental frequency error signal to obtain a microwave frequency locking error signal, and obtaining the control quantity of the microwave frequency control loop according to the microwave frequency locking error signal. The invention avoids the mutual interference of two modulation signals, decouples the phase of the demodulation result and the reference signal, and improves the frequency locking convergence speed and the control precision.
Description
Technical Field
The invention relates to the technical field of atomic clock control, in particular to a method and equipment for controlling the frequency of an atomic clock.
Background
The atomic clock is widely applied to the fields of aerospace, navigation, time synchronization equipment, frequency detection reference and the like, the problems of inflexibility, multiple components, aging, temperature drift, difficulty in debugging, long research and development period and the like exist in the traditional analog control, and the application requirement of a Coherent Population Trapping (CPT) atomic clock is difficult to adapt. In the application of the CPT atomic clock, microwave signals are superposed on the laser driving current of the CPT atomic clock in a related control mode, and the driving current and radio frequency signals of the laser are required to be modulated respectively, so that the phenomenon that the two modulation signals interfere with each other exists; because the CPT atomic clock is very sensitive to current and temperature, useful signals are submerged in noise signals, and related photoelectric signal detection of the atomic clock is easily influenced by device nonlinearity, ambient temperature and additional phase shift, so that the CPT atomic clock has the problems of poor convergence effect, slow locking, easy oscillation and overshoot, even lock losing and the like, and cannot be well applied to the working condition scene. Therefore, it is an urgent technical problem in the art to develop a method and apparatus for controlling the frequency of an atomic clock, which can effectively overcome the above-mentioned drawbacks in the related art.
Disclosure of Invention
In view of the above problems in the prior art, embodiments of the present invention provide a method and an apparatus for controlling a frequency of an atomic clock.
In a first aspect, an embodiment of the present invention provides an atomic clock frequency control method, including: scanning direct current of a laser, performing peak value search on a received Doppler absorption spectrum line signal to obtain laser fundamental frequency current, loading a modulation signal on the laser fundamental frequency current to obtain a laser fundamental frequency error signal, adjusting laser fundamental frequency according to the laser fundamental frequency error signal, and locking the laser fundamental frequency; scanning a microwave frequency signal to obtain a CPT resonance spectral line, performing peak value search on the CPT resonance spectral line to obtain the central frequency of the microwave frequency signal, performing 2FSK modulation on the central frequency to obtain a microwave 2FSK modulation signal, demodulating the laser fundamental frequency error signal according to the microwave 2FSK modulation signal to obtain a microwave frequency locking error signal, and obtaining the control quantity of a microwave frequency control loop according to the microwave frequency locking error signal; wherein CPT is coherent population trapping.
On the basis of the content of the above method embodiment, the atomic clock frequency control method provided in the embodiment of the present invention, where the scanning of the direct current of the laser includes: selecting a laser with the wavelength of 795nm as a light source, changing the direct current of the laser through linear continuous scanning to obtain a Doppler absorption signal of the CPT atomic clock, and forming an absorption peak if the laser frequency is equal to the transition frequency of a quantum system.
On the basis of the content of the above method embodiment, the atomic clock frequency control method provided in the embodiment of the present invention, which performs peak search on the received doppler absorption spectrum line signal to obtain a laser fundamental frequency current, includes: and recording the output laser direct current value and the corresponding photoelectric signal detection value, completing laser driving current scanning in a single complete period, and searching the maximum value of the recorded photoelectric signal detection value, wherein the laser direct current corresponding to the maximum value is the laser fundamental frequency current.
On the basis of the content of the above method embodiment, the atomic clock frequency control method provided in the embodiment of the present invention, where the loading of the modulation signal to the laser fundamental frequency current to obtain the laser fundamental frequency error signal, includes: and (3) applying shallow amplitude sinusoidal modulation to the input current of the laser by adopting quadrature modulation and demodulation, wherein the current modulation frequency is 4 kHz-10 kHz, and the modulation amplitude is less than 10 uA.
On the basis of the content of the above method embodiment, the atomic clock frequency control method provided in the embodiment of the present invention, in which the scanning of the microwave frequency signal to obtain the CPT resonance line and the peak search of the CPT resonance line to obtain the center frequency of the microwave frequency signal, includes: linearly scanning the microwave frequency at 3.417GHz, and if the process that the signal is changed from weak to strong is detected, adopting microwave frequency scanning to obtain a CPT resonance spectral line; and recording the output microwave frequency value and the corresponding CPT resonance signal detection value, scanning the microwave frequency of a complete period, and acquiring the maximum value of the CPT resonance signal detection value, wherein the microwave frequency value corresponding to the maximum value is the microwave center frequency.
On the basis of the content of the above method embodiment, the atomic clock frequency control method provided in the embodiment of the present invention, obtaining a control quantity of a microwave frequency control loop according to the microwave frequency locking error signal, includes: initializing controller parameters and control quantities; judging the offset range according to the 2FSK demodulation result; changing the control step length; and obtaining the control quantity of the microwave frequency control loop according to the control step length and the current frequency offset range.
In a second aspect, an embodiment of the present invention provides an atomic clock frequency control system, including: the laser direct current drive is used for receiving the digital control signal and generating a drive current; the radio frequency coupling unit is used for coupling the driving current and a radio frequency signal; a laser for generating laser light; the quantum system is used for acquiring a Doppler absorption signal with a high signal-to-noise ratio and a CPT signal; the photoelectric signal acquisition unit is used for converting photocurrent into an analog voltage signal and converting the analog voltage signal into a digital voltage signal; the phase-locked frequency multiplication unit is used for outputting a radio frequency signal and generating a 2FSK modulation signal; the temperature compensation voltage control crystal oscillator is used for generating a stable frequency signal; the crystal oscillator voltage control unit is used for converting the control quantity of the microprocessor into a deviation correcting signal; a microprocessor for implementing the atomic clock frequency control method of any of the preceding method embodiments.
In a third aspect, an embodiment of the present invention provides an atomic clock frequency control apparatus, including:
the base frequency locking module is used for scanning direct current of the laser, performing peak value search on the received Doppler absorption spectrum line signal to obtain laser base frequency current, loading a modulation signal on the laser base frequency current to obtain a laser base frequency error signal, adjusting the laser base frequency according to the laser base frequency error signal and locking the laser base frequency; the control quantity acquisition module is used for scanning a microwave frequency signal to obtain a CPT resonance spectral line, performing peak value search on the CPT resonance spectral line to obtain the central frequency of the microwave frequency signal, performing 2FSK modulation on the central frequency to obtain a microwave 2FSK modulation signal, demodulating the laser fundamental frequency error signal according to the microwave 2FSK modulation signal to obtain a microwave frequency locking error signal, and obtaining the control quantity of a microwave frequency control loop according to the microwave frequency locking error signal; wherein CPT is coherent population trapping.
In a fourth aspect, an embodiment of the present invention provides an electronic device, including:
at least one processor; and
at least one memory communicatively coupled to the processor, wherein:
the memory stores program instructions executable by the processor, the processor invoking the program instructions to perform the atomic clock frequency control method provided by any of the various implementations of the first aspect.
In a fifth aspect, embodiments of the present invention provide a non-transitory computer-readable storage medium storing computer instructions for causing a computer to perform the atomic clock frequency control method provided in any one of the various implementations of the first aspect.
According to the atomic clock frequency control method and device provided by the embodiment of the invention, the laser fundamental frequency locking loop and the microwave locking loop are controlled in a time-sharing manner, the driving current and the radio frequency signal of the laser are modulated in a time-sharing manner, the mutual interference of the two modulation signals is avoided, the difficulty of signal demodulation and circuit debugging is reduced, the demodulation result and the reference signal are decoupled in phase by adopting quadrature modulation and demodulation and 2FSK modulation and demodulation, meanwhile, the nonlinear PI locking controller avoids oscillation and overshoot, and the frequency locking convergence speed and control precision are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description will be given below to the drawings required for the description of the embodiments or the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a flow chart of an atomic clock frequency control method according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an atomic clock frequency control apparatus according to an embodiment of the present invention;
fig. 3 is a schematic physical structure diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. In addition, technical features of various embodiments or individual embodiments provided by the present invention may be arbitrarily combined with each other to form a feasible technical solution, and such combination is not limited by the sequence of steps and/or the structural composition mode, but must be realized by a person skilled in the art, and when the technical solution combination is contradictory or cannot be realized, such a technical solution combination should not be considered to exist and is not within the protection scope of the present invention.
The embodiment of the invention provides a method for controlling the frequency of an atomic clock, and referring to fig. 1, the method comprises the following steps: scanning direct current of a laser, performing peak value search on a received Doppler absorption spectrum line signal to obtain laser fundamental frequency current, loading a modulation signal on the laser fundamental frequency current to obtain a laser fundamental frequency error signal, adjusting laser fundamental frequency according to the laser fundamental frequency error signal, and locking the laser fundamental frequency; scanning a microwave frequency signal to obtain a CPT resonance spectral line, performing peak value search on the CPT resonance spectral line to obtain the central frequency of the microwave frequency signal, performing 2FSK modulation on the central frequency to obtain a microwave 2FSK modulation signal, demodulating the laser fundamental frequency error signal according to the microwave 2FSK modulation signal to obtain a microwave frequency locking error signal, and obtaining the control quantity of a microwave frequency control loop according to the microwave frequency locking error signal; wherein CPT is coherent population trapping. It should be noted that, to obtain a stable microwave lock signal, the premise is to lock the laser fundamental frequency through modulation and demodulation, so that the cpt phenomenon can only occur by locking the laser fundamental frequency (wavelength) through the absorption peak, and then a stable control amount can be obtained through the microwave modulation and demodulation signal.
Based on the content of the foregoing method embodiment, as an optional embodiment, the atomic clock frequency control method provided in the embodiment of the present invention, the scanning of the direct current of the laser includes: selecting a laser with the wavelength of 795nm as a light source, changing the direct current of the laser through linear continuous scanning to obtain a Doppler absorption signal of the CPT atomic clock, and forming an absorption peak if the laser frequency is equal to the transition frequency of a quantum system.
Specifically, a laser with the wavelength of 795nm is selected as a light source, the Doppler absorption signal of the CPT atomic clock is obtained by changing the direct current of the laser through linear continuous scanning, and when the laser frequency is equal to the transition frequency of a quantum system, an absorption peak is formed by photoelectric signal detection.
Based on the content of the foregoing method embodiment, as an optional embodiment, the atomic clock frequency control method provided in the embodiment of the present invention, which performs peak search on the received doppler absorption spectrum line signal to obtain a laser fundamental frequency current, includes: and recording the output laser direct current value and the corresponding photoelectric signal detection value, completing laser driving current scanning in a single complete period, and searching the maximum value of the recorded photoelectric signal detection value, wherein the laser direct current corresponding to the maximum value is the laser fundamental frequency current.
Specifically, the microprocessor records the output laser direct current value and the corresponding photoelectric signal detection value, searches the maximum value of the recorded photoelectric signal detection value after completing the laser driving current scanning of the whole period, and takes the laser direct current value corresponding to the maximum value as the laser fundamental frequency current value.
Based on the content of the above method embodiment, as an optional embodiment, the method for controlling the frequency of the atomic clock provided in the embodiment of the present invention, where the loading of the modulation signal to the laser fundamental frequency current to obtain the laser fundamental frequency error signal, includes: and (3) applying shallow amplitude sinusoidal modulation to the input current of the laser by adopting quadrature modulation and demodulation, wherein the current modulation frequency is 4 kHz-10 kHz, and the modulation amplitude is less than 10 uA.
Specifically, because the useful signal is weak, a quadrature modulation and demodulation method is adopted to apply shallow amplitude sinusoidal modulation to the input current of the laser, the current modulation frequency is selected from 4kHz to 10kHz, and the modulation amplitude is less than 10 uA.
Based on the content of the foregoing method embodiment, as an optional embodiment, the atomic clock frequency control method provided in the embodiment of the present invention, where the scanning a microwave frequency signal to obtain a CPT resonance line, and performing peak search on the CPT resonance line to obtain a center frequency of the microwave frequency signal, includes: linearly scanning the microwave frequency at 3.417GHz, and if the process that the signal is changed from weak to strong is detected, adopting microwave frequency scanning to obtain a CPT resonance spectral line; and recording the output microwave frequency value and the corresponding CPT resonance signal detection value, scanning the microwave frequency of a complete period, and acquiring the maximum value of the CPT resonance signal detection value, wherein the microwave frequency value corresponding to the maximum value is the microwave center frequency.
Specifically, demodulation of the detection signal requires the use of a reference signal, and the elimination of the phase difference between the reference signal and the photodetection signal will affect the demodulation result, and in order to eliminate this effect, the principle of digital quadrature demodulation is employed. By linearly scanning the microwave frequency near 3.417GHz, the process that the signal is changed from weak to strong and then from strong to weak can be detected in the photoelectric signal detection unit, namely the CPT resonance line can be obtained by microwave frequency scanning. The microprocessor records the output microwave frequency value and the corresponding CPT resonance signal detection value, searches the maximum value of the recorded photoelectric signal detection value after completing the microwave frequency scanning of the whole period, and takes the microwave frequency value corresponding to the maximum value as the microwave center frequency.
Based on the content of the foregoing method embodiment, as an optional embodiment, the method for controlling a frequency of an atomic clock provided in the embodiment of the present invention, where obtaining a control quantity of a microwave frequency control loop according to the microwave frequency locking error signal includes: initializing controller parameters and control quantities; judging the offset range according to the 2FSK demodulation result; changing the control step length; and obtaining the control quantity of the microwave frequency control loop according to the control step length and the current frequency offset range.
Specifically, controller parameters and control quantities are initialized; acquiring a 2FSK demodulation result; judging an offset range according to a demodulation result; changing the control step length, and dynamically adjusting the control step length in real time according to the nonlinear relation between the voltage-controlled voltage of the crystal oscillator and the output frequency of the crystal oscillator by the microwave frequency controller by adopting a nonlinear control principle; calculating a control quantity, wherein the current control quantity is determined by a control step length and a current frequency offset range, and a proportional integral type nonlinear PI controller is adopted, wherein a proportional parameter KP and an integral parameter KI of the PI controller change along with the frequency offset range, the deviation is adjusted rapidly and in a large step length when the frequency offset range is large, and the deviation is adjusted finely when the frequency offset range is small, so that the system oscillation is avoided, and the control precision is improved; the microwave frequency control quantity is output to the crystal oscillator voltage control unit. And finally, the control quantity of the microwave frequency control loop is used for controlling the amplitude of the output voltage of the crystal oscillator voltage control unit, so that the correction of the output frequency of the crystal oscillator is completed.
According to the atomic clock frequency control method provided by the embodiment of the invention, the laser fundamental frequency locking loop and the microwave locking loop are controlled in a time-sharing manner, the driving current and the radio frequency signal of the laser are modulated in a time-sharing manner, the mutual interference of the two modulation signals is avoided, the difficulty of signal demodulation and circuit debugging is reduced, the demodulation result and the reference signal are decoupled in phase by adopting quadrature modulation and demodulation and 2FSK modulation and demodulation, meanwhile, the nonlinear PI locking controller avoids oscillation and overshoot, and the frequency locking convergence speed and the control precision are improved.
An embodiment of the present invention provides an atomic clock frequency control system, including: the laser direct current drive is used for receiving the digital control signal and generating a drive current; the radio frequency coupling unit is used for coupling the driving current with a radio frequency signal; a laser for generating laser light; the quantum system is used for acquiring a Doppler absorption signal with a high signal-to-noise ratio and a CPT signal; the photoelectric signal acquisition unit is used for converting photocurrent into an analog voltage signal and converting the analog voltage signal into a digital voltage signal; the PLL phase-locking frequency multiplication unit (namely a phase-locking frequency multiplication unit) is used for outputting a radio frequency signal and generating a 2FSK modulation signal; the TCXO temperature compensated voltage controlled crystal oscillator (namely the temperature compensated voltage controlled crystal oscillator) is used for generating a stable frequency signal; the crystal oscillator voltage control unit is used for converting the control quantity of the microprocessor into a deviation correcting signal; a microprocessor for implementing the atomic clock frequency control method of any of the preceding method embodiments.
Specifically, the laser direct current drive 1 is connected to the laser 6 through the radio frequency coupling unit 5, the laser direct current drive 1 adopts a high-precision DA conversion chip, receives a digital control signal from the microprocessor 9, generates a driving current applied to the laser 6, the radio frequency coupling unit 5 couples output signals of the laser direct current drive 1 and the PLL phase-locked frequency doubling unit 4 to the laser 6 through an inductor and a capacitor respectively, and the laser 6 integrates a TEC (semiconductor cooler) and a thermistor to enable the laser to work at a set temperature. The quantum system 7 comprises a heating coil, a magnetic field coil, a temperature measuring resistor, a physical cavity and a PD photoelectric detector inside, photocurrent output by the quantum system 7 is transmitted to a photoelectric signal acquisition unit 8, and laser passes through the quantum system 7 to obtain Doppler absorption signals and CPT signals with high signal-to-noise ratio. The photoelectric signal acquisition unit 8 transmits the Doppler absorption signal and the CPT signal to the microprocessor 9; the photoelectric signal acquisition unit 8 comprises a high-precision trans-impedance amplifier and a 24-bit AD conversion chip, the high-precision trans-impedance amplifier converts photocurrent of the quantum system into a voltage signal of 0V-5V, and the 24-bit AD conversion chip converts an analog voltage signal into a digital quantity and sends the digital quantity to the microprocessor 9; the TCXO temperature compensation voltage control crystal oscillator 3 generates a high-stability 10MHz frequency signal, adjusts the output frequency of the crystal oscillator according to the output voltage of the crystal oscillator voltage control unit 2, and uses the output 10MHz frequency signal as a reference clock of the PLL phase-locking frequency doubling unit 4; the PLL phase-locking frequency doubling unit 4 adopts a radio frequency chip with 48-bit frequency control words and an integrated voltage controlled oscillator VCO, and controls the output of the PLL phase-locking frequency doubling unit 4 to output 3.417GHz radio frequency signals and generate 2FSK modulation signals through a digital bus of a microprocessor 9; the crystal oscillator voltage control unit 2 comprises a 24-bit DA conversion chip, converts the control quantity of the microprocessor 9 into a microwave frequency 0V-5V deviation correction signal, and is used for controlling the TCXO temperature compensation voltage control crystal oscillator 3, adjusting the output frequency of the crystal oscillator and improving the stability of the CPT atomic clock; the microprocessor 9 executes the flow control of the laser fundamental frequency locking loop and the microwave frequency locking loop, controls the laser direct current drive 1 and the PLL phase-locking frequency doubling unit 4 to respectively perform laser frequency scanning and microwave frequency scanning, also completes the digital quadrature modulation and demodulation of laser fundamental frequency signals, the digital FSK modulation and demodulation of microwave frequency 2 and the nonlinear frequency locking controller, and communicates with the peripheral laser direct current drive 1, the PLL phase-locking frequency doubling unit 4, the crystal oscillator voltage control unit 2 and the photoelectric signal acquisition unit 8 through an SPI bus;
the laser direct current drive 1 receives a digital control signal from the microprocessor 9 and generates a drive current which is applied to the laser 6; the crystal oscillator voltage control unit 2 converts the control quantity of the microprocessor 9 into a microwave frequency deviation correction signal for controlling the TCXO temperature compensation voltage control crystal oscillator 3 and adjusting the output frequency of the crystal oscillator; the TCXO temperature compensating voltage controlled crystal oscillator 3 generates stable output frequency, finely adjusts the output frequency according to the deviation correcting signal, and takes the output frequency as a reference clock of the PLL phase-locking frequency doubling unit 4; the radio frequency coupling unit 5 couples the signals of the laser direct current drive 1 and the PLL phase-locking frequency doubling unit 4 and then applies the coupled signals to the laser 6; the laser 6 receives the driving current from the radio frequency coupling unit 5 to generate modulated laser, and the laser is incident to the quantum system 7; the quantum system 7 interacts with incident laser to form a Doppler absorption optical signal and a CPT optical signal, and converts the Doppler absorption optical signal and the CPT optical signal into voltage signals; the photoelectric signal acquisition unit 8 converts the optical signal into digital quantity and sends the digital quantity to the microprocessor 9.
The embodiments of the invention disclose a time-sharing control scheme for a laser fundamental frequency locking loop and a microwave locking loop, which carries out time-sharing modulation on a driving current and a radio frequency signal of a laser, avoids mutual interference of the two modulation signals, greatly reduces the calculation resources required by digital operation and workflow control, and simultaneously reduces the difficulty of signal extraction. The Doppler absorption spectral line and the CPT resonance spectral line are respectively adopted to adopt a signal processing scheme of digital quadrature modulation and demodulation and digital 2FSK modulation and demodulation, additional phase shift is not introduced, and the digital 2FSK modulation and demodulation are easy to realize. The nonlinear PI locking controller is adopted to improve the frequency locking control precision and speed, the frequency discrimination signal of the common CPT atomic clock frequency locking loop directly acts on a control object, the convergence effect is poor, the locking is slow, oscillation and overshoot are easy to occur, even the lock is lost, and the ideal control effect is difficult to achieve.
The implementation basis of the various embodiments of the present invention is realized by programmed processing performed by a device having a processor function. Therefore, in engineering practice, the technical solutions and functions thereof of the embodiments of the present invention can be packaged into various modules. Based on this reality, on the basis of the above embodiments, embodiments of the present invention provide an atomic clock frequency control apparatus for executing the atomic clock frequency control method in the above method embodiments. Referring to fig. 2, the apparatus includes: the base frequency locking module is used for scanning direct current of the laser, performing peak value search on the received Doppler absorption spectrum line signal to obtain laser base frequency current, loading a modulation signal on the laser base frequency current to obtain a laser base frequency error signal, adjusting the laser base frequency according to the laser base frequency error signal and locking the laser base frequency; the control quantity acquisition module is used for scanning a microwave frequency signal to obtain a CPT resonance spectral line, performing peak value search on the CPT resonance spectral line to obtain the central frequency of the microwave frequency signal, performing 2FSK modulation on the central frequency to obtain a microwave 2FSK modulation signal, demodulating the laser fundamental frequency error signal according to the microwave 2FSK modulation signal to obtain a microwave frequency locking error signal, and obtaining the control quantity of a microwave frequency control loop according to the microwave frequency locking error signal; wherein CPT is coherent population trapping.
The atomic clock frequency control device provided by the embodiment of the invention adopts various modules in fig. 2, controls the laser fundamental frequency locking loop and the microwave locking loop in a time-sharing manner, and modulates the driving current and the radio frequency signal of the laser in a time-sharing manner, so that the mutual interference of the two modulation signals is avoided, the difficulty of signal demodulation and circuit debugging is reduced, the quadrature modulation and demodulation and the 2FSK modulation and demodulation are adopted, the demodulation result and the reference signal are decoupled in phase, and meanwhile, the nonlinear PI locking controller avoids oscillation and overshoot, and the frequency locking convergence speed and the control precision are improved.
It should be noted that, the apparatus in the apparatus embodiment provided by the present invention may be used for implementing methods in other method embodiments provided by the present invention, except that corresponding function modules are provided, and the principle of the apparatus embodiment provided by the present invention is basically the same as that of the apparatus embodiment provided by the present invention, so long as a person skilled in the art obtains corresponding technical means by combining technical features on the basis of the apparatus embodiment described above, and obtains a technical solution formed by these technical means, on the premise of ensuring that the technical solution has practicability, the apparatus in the apparatus embodiment described above may be modified, so as to obtain a corresponding apparatus class embodiment, which is used for implementing methods in other method class embodiments. For example:
based on the content of the above device embodiment, as an optional embodiment, the atomic clock frequency control device provided in the embodiment of the present invention further includes: a second module for direct current of the scanning laser, comprising: selecting a laser with the wavelength of 795nm as a light source, changing the direct current of the laser through linear continuous scanning to obtain a Doppler absorption signal of the CPT atomic clock, and forming an absorption peak if the laser frequency is equal to the transition frequency of a quantum system.
Based on the content of the above device embodiment, as an optional embodiment, the atomic clock frequency control device provided in the embodiment of the present invention further includes: a third module, configured to perform peak search on the received doppler absorption spectrum line signal to obtain a laser fundamental frequency current, where the peak search includes: and recording the output laser direct current value and the corresponding photoelectric signal detection value, completing laser driving current scanning in a single complete period, and searching the maximum value of the recorded photoelectric signal detection value, wherein the laser direct current corresponding to the maximum value is the laser fundamental frequency current.
Based on the content of the above device embodiment, as an optional embodiment, the atomic clock frequency control device provided in the embodiment of the present invention further includes: a fourth module, configured to load a modulation signal on the laser fundamental frequency current to obtain a laser fundamental frequency error signal, where the fourth module includes: and (3) applying shallow amplitude sinusoidal modulation to the input current of the laser by adopting quadrature modulation and demodulation, wherein the current modulation frequency is 4 kHz-10 kHz, and the modulation amplitude is less than 10 uA.
Based on the content of the above device embodiment, as an optional embodiment, the atomic clock frequency control device provided in the embodiment of the present invention further includes: a fifth module, configured to scan the microwave frequency signal to obtain a CPT resonance line, perform peak search on the CPT resonance line to obtain a center frequency of the microwave frequency signal, where the fifth module includes: linearly scanning the microwave frequency at 3.417GHz, and if the process that the signal is changed from weak to strong is detected, adopting microwave frequency scanning to obtain a CPT resonance spectral line; and recording the output microwave frequency value and the corresponding CPT resonance signal detection value, scanning the microwave frequency of a complete period, and acquiring the maximum value of the CPT resonance signal detection value, wherein the microwave frequency value corresponding to the maximum value is the microwave center frequency.
Based on the content of the above device embodiment, as an optional embodiment, the atomic clock frequency control device provided in the embodiment of the present invention further includes: a sixth module, configured to obtain a control quantity of a microwave frequency control loop according to the microwave frequency locking error signal, where the sixth module includes: initializing controller parameters and control quantities; judging the offset range according to the 2FSK demodulation result; changing the control step length; and obtaining the control quantity of the microwave frequency control loop according to the control step length and the current frequency offset range.
The method of the embodiment of the invention is realized by depending on the electronic equipment, so that the related electronic equipment is necessarily introduced. To this end, an embodiment of the present invention provides an electronic apparatus, as shown in fig. 3, including: at least one processor (processor)301, a communication Interface (Communications Interface)304, at least one memory (memory)302 and a communication bus 303, wherein the at least one processor 301, the communication Interface 304 and the at least one memory 302 are configured to communicate with each other via the communication bus 303. The at least one processor 301 may invoke logic instructions in the at least one memory 302 to perform all or a portion of the steps of the methods provided by the various method embodiments described above.
Furthermore, the logic instructions in the at least one memory 302 may be implemented in software functional units and stored in a computer readable storage medium when sold or used as a stand-alone product. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the method embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. Based on this recognition, each block in the flowchart or block diagrams may represent a module, a program segment, or a portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In this patent, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. An atomic clock frequency control method, comprising: scanning direct current of a laser, performing peak value search on a received Doppler absorption spectrum line signal to obtain laser fundamental frequency current, loading a modulation signal on the laser fundamental frequency current to obtain a laser fundamental frequency error signal, adjusting laser fundamental frequency according to the laser fundamental frequency error signal, and locking the laser fundamental frequency; scanning a microwave frequency signal to obtain a CPT resonance spectral line, performing peak value search on the CPT resonance spectral line to obtain the central frequency of the microwave frequency signal, performing 2FSK modulation on the central frequency to obtain a microwave 2FSK modulation signal, demodulating the laser fundamental frequency error signal according to the microwave 2FSK modulation signal to obtain a microwave frequency locking error signal, and obtaining the control quantity of a microwave frequency control loop according to the microwave frequency locking error signal; wherein CPT is coherent population trapping.
2. The atomic clock frequency control method of claim 1, wherein sweeping the dc current of the laser comprises: selecting a laser with the wavelength of 795nm as a light source, changing the direct current of the laser through linear continuous scanning to obtain a Doppler absorption signal of the CPT atomic clock, and forming an absorption peak if the laser frequency is equal to the transition frequency of a quantum system.
3. The method for controlling the frequency of an atomic clock according to claim 1, wherein the step of performing a peak search on the received Doppler absorption line signal to obtain a laser fundamental frequency current comprises: and recording the output laser direct current value and the corresponding photoelectric signal detection value, completing laser driving current scanning in a single complete period, and searching the maximum value of the recorded photoelectric signal detection value, wherein the laser direct current corresponding to the maximum value is the laser fundamental frequency current.
4. The method for controlling the frequency of an atomic clock according to claim 1, wherein the step of applying a modulation signal to the laser fundamental frequency current to obtain a laser fundamental frequency error signal comprises: and (3) applying shallow amplitude sinusoidal modulation to the input current of the laser by adopting quadrature modulation and demodulation, wherein the current modulation frequency is 4 kHz-10 kHz, and the modulation amplitude is less than 10 uA.
5. The atomic clock frequency control method according to claim 1, wherein the scanning the microwave frequency signal to obtain a CPT resonance line, and performing a peak search on the CPT resonance line to obtain a center frequency of the microwave frequency signal includes: linearly scanning the microwave frequency at 3.417GHz, and if the process that the signal is changed from weak to strong is detected, adopting microwave frequency scanning to obtain a CPT resonance spectral line; and recording the output microwave frequency value and the corresponding CPT resonance signal detection value, scanning the microwave frequency of a complete period, and acquiring the maximum value of the CPT resonance signal detection value, wherein the microwave frequency value corresponding to the maximum value is the microwave center frequency.
6. The method for controlling the frequency of an atomic clock according to claim 1, wherein the obtaining the control quantity of the microwave frequency control loop according to the microwave frequency locking error signal comprises: initializing controller parameters and control quantities; judging the offset range according to the 2FSK demodulation result; changing the control step length; and obtaining the control quantity of the microwave frequency control loop according to the control step length and the current frequency offset range.
7. An atomic clock frequency control system, comprising:
the laser direct current drive is used for receiving the digital control signal and generating a drive current;
the radio frequency coupling unit is used for coupling the driving current and a radio frequency signal;
a laser for generating laser light;
the quantum system is used for acquiring a Doppler absorption signal with a high signal-to-noise ratio and a CPT signal;
the photoelectric signal acquisition unit is used for converting photocurrent into an analog voltage signal and converting the analog voltage signal into a digital voltage signal;
the phase-locked frequency multiplication unit is used for outputting a radio frequency signal and generating a 2FSK modulation signal;
the temperature compensation voltage control crystal oscillator is used for generating a stable frequency signal;
the crystal oscillator voltage control unit is used for converting the control quantity of the microprocessor into a deviation correcting signal;
a microprocessor for implementing an atomic clock frequency control method as claimed in any one of claims 1 to 6.
8. An atomic clock frequency control apparatus, comprising:
the base frequency locking module is used for scanning direct current of the laser, performing peak value search on the received Doppler absorption spectrum line signal to obtain laser base frequency current, loading a modulation signal on the laser base frequency current to obtain a laser base frequency error signal, adjusting the laser base frequency according to the laser base frequency error signal and locking the laser base frequency; the control quantity acquisition module is used for scanning a microwave frequency signal to obtain a CPT resonance spectral line, performing peak value search on the CPT resonance spectral line to obtain the central frequency of the microwave frequency signal, performing 2FSK modulation on the central frequency to obtain a microwave 2FSK modulation signal, demodulating the laser fundamental frequency error signal according to the microwave 2FSK modulation signal to obtain a microwave frequency locking error signal, and obtaining the control quantity of a microwave frequency control loop according to the microwave frequency locking error signal; wherein CPT is coherent population trapping.
9. An electronic device, comprising:
at least one processor, at least one memory, and a communication interface; wherein the content of the first and second substances,
the processor, the memory and the communication interface are communicated with each other;
the memory stores program instructions executable by the processor, the processor invoking the program instructions to perform the method of any of claims 1 to 6.
10. A non-transitory computer-readable storage medium storing computer instructions for causing a computer to perform the method of any one of claims 1 to 6.
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| CN114153135A (en) * | 2021-12-22 | 2022-03-08 | 北京大学 | Locking method of cesium beam atomic clock |
| CN114844619A (en) * | 2022-05-13 | 2022-08-02 | 南京尤尼泰信息科技有限公司 | Frequency signal generating device and method based on satellite navigation signal |
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