Microwave generation device and method of cold atom microwave clock

Abstract

The invention provides a cold atom microwave clock microwave generation device and method, and the device comprises a high-stability voltage source which is electrically connected with a digital-to-analog converter, serves as a reference voltage source of the digital-to-analog converter, and is used for generating a reference voltage of the digital-to-analog converter; the reference clock signal generation module is electrically connected with the digital-to-analog converter and is used for generating a reference clock signal of the digital-to-analog converter; the control module is electrically connected with the digital-to-analog converter and is used for controlling the output frequency or the output amplitude of the digital-to-analog converter; and the digital-to-analog converter is used for generating a synthetic signal, namely a target microwave frequency signal, by utilizing the frequency mixing characteristic under the control of the control module based on the reference clock signal. According to the cold atom microwave clock microwave generation device, a digital circuit processing method is adopted, a target microwave frequency signal is directly generated, the immune characteristic and the anti-interference capability of a microwave source to the environment temperature can be improved, and in addition, the microwave circuit of the cold atom microwave clock microwave generation device is simple in structure and low in cost.

Description

Technical Field

[0001] This invention relates to the field of cold atom frequency standards, and in particular to a cold atom microwave clock microwave generation device and method. Background Technology

[0002] Cold atom microwave clocks primarily utilize the interaction of separated oscillating fields between cold atoms and microwaves to generate frequency discrimination curves, thereby enabling the local oscillator to output frequency signals with high stability and accuracy. The microwave cavity, as the core device of the cold atom clock, provides a space for transitions between the microwave radiation field and the two hyperfine energy levels of the cold atom's ground state after the atoms have been cooled. However, specific microwave signals need to be injected externally into the microwave cavity to form the required microwave energy field. For example, in a rubidium atom-based fountain clock, a π-pulse microwave signal needs to be injected into the selected state microwave cavity to prepare the rubidium atoms, moving some atoms from the ground state energy level to the lower ground state energy level. Simultaneously, two separate π / 2-pulse microwave signals need to be injected into the excitation microwave cavity to interact with the rubidium atoms through separated oscillating fields, forming the Ramsey frequency discrimination curve. In a rubidium atom-based integrating sphere cold atom clock, only two separate π / 2-pulse microwave signals need to be injected into a single microwave cavity to interact with the rubidium atoms through separated oscillating fields, forming the Ramsey frequency discrimination curve.

[0003] As can be seen from the two examples above, in cold atom clocks, microwave signals directly interact with rubidium atoms. The stability of the output frequency and power of the microwave signal directly determines the atom state selection efficiency, the signal-to-noise ratio of the Ramsey discriminant curve, and the stability of the output signal after the clock is closed-loop locked. Microwave signals are generated by specific microwave sources, which are constructed from multiple microwave devices. The operating characteristics of these devices are all related to ambient temperature, meaning that the characteristics of the microwave signal are inevitably affected by the ambient temperature.

[0004] In summary, the sensitivity of microwave signals to ambient temperature translates into the sensitivity of atomic state selection efficiency, the signal-to-noise ratio of the Ramsey discriminant curve, and the stability of the output signal after the final clock loop lock-up to ambient temperature. Therefore, it is crucial to reduce the sensitivity of microwave signals to ambient temperature, thereby reducing the sensitivity of the output signal stability after the final clock loop lock-up to ambient temperature. This improves the clock's resistance to interference and immunity to ambient temperature, thereby enhancing the stability and robustness of the clock's performance. Ultimately, this enhances the long-term performance retention of cold atom clocks, laying the foundation for their engineering development and widespread application in harsh environments such as non-laboratory settings.

[0005] In existing technologies, cold atom microwave clocks based on rubidium atoms primarily employ a DDS to generate a microwave signal with a fractional frequency of 34.682610 MHz, which is then mixed with a 6800 MHz DRO (Dielectric Resonator Oscillator) to output the final required 6834.682610 MHz microwave signal. The temperature characteristics of the 6834.682610 MHz microwave signal amplitude are directly determined by the temperature characteristics of the DDS, mixer, and DRO, but these devices typically have temperature characteristics between 1000 and 2000 ppm / ℃. This would cause the temperature characteristics of the 6834.682610 MHz microwave signal to remain at the 1000 ppm / ℃ level, failing to meet the long-term stability requirements of the cold atom microwave clock. Improving the temperature characteristics would require more subsequent auxiliary circuitry, such as amplitude stabilization loops and temperature control circuits, which would not only increase circuit complexity and the cost of the microwave source but also reduce the overall clock's reliability and robustness.

[0006] Therefore, there is an urgent need for a cold atom microwave clock microwave generating device that can improve the microwave source's immunity to ambient temperature, while simplifying the microwave circuit and improving the reliability of the microwave source. Summary of the Invention

[0007] This invention provides a cold atom microwave clock microwave generating device, comprising:

[0008] A highly stable voltage source, electrically connected to the digital-to-analog converter (DAC), is used as the reference voltage source for the DAC to generate the reference voltage for the DAC.

[0009] The reference clock signal generation module is electrically connected to the digital-to-analog converter and is used to generate the reference clock signal for the digital-to-analog converter.

[0010] The control module, electrically connected to the digital-to-analog converter, is used to control the output frequency or output amplitude of the digital-to-analog converter;

[0011] The digital-to-analog converter, based on a reference clock signal and under the control of the control module, uses mixing characteristics to generate a synthesized signal, namely the target microwave frequency signal.

[0012] Furthermore, the reference clock signal generation module includes:

[0013] A signal source used to generate clock signals;

[0014] A dielectric resonant oscillator, electrically connected to a signal source, is used to output a frequency signal. The frequency signal is locked to a clock signal and serves as the reference clock signal for the digital-to-analog converter.

[0015] Furthermore, the control module includes:

[0016] Control unit, used to generate control words;

[0017] The read-only memory is electrically connected to the control unit at one end and to the digital-to-analog converter at the other end. The memory parameters of the read-only memory are set based on the control word, and the control data stream is output to control the output frequency or output amplitude of the digital-to-analog converter.

[0018] Furthermore, the control unit is also electrically connected to the dielectric resonant oscillator to control the output frequency signal of the dielectric resonant oscillator.

[0019] Furthermore, the control module also includes a communication port, which is electrically connected to the control unit and used to communicate with the host computer to transmit control commands.

[0020] Furthermore, the high-stability voltage source is a DC power supply.

[0021] Furthermore, the frequency signal is a high-frequency signal.

[0022] Furthermore, the digital-to-analog converter has a working bit width of 16 bits.

[0023] Furthermore, the reference clock signal has a frequency of 2500MHz, the control module controls the output frequency of the digital-to-analog converter to be 665.31739MHz, and the target microwave frequency signal has a frequency of 6834.682610MHz.

[0024] This invention also provides a method for generating microwaves using a cold atom microwave clock, comprising the following steps:

[0025] Generate the reference voltage for the digital-to-analog converter;

[0026] Generate a reference clock signal for the digital-to-analog converter;

[0027] Control the output frequency or output amplitude of the digital-to-analog converter;

[0028] The digital-to-analog converter generates a synthesized signal, namely the target microwave frequency signal, based on the reference clock signal and using the mixing characteristics.

[0029] The present invention provides a cold atom microwave clock microwave generating device, which employs a high-stability voltage source, a reference clock signal generation module, a control module, and a digital-to-analog converter. The high-stability voltage source generates a reference voltage for the digital-to-analog converter, the reference clock signal generation module generates a reference clock signal for the digital-to-analog converter, and the control module controls the output frequency or output amplitude of the digital-to-analog converter. Based on the reference clock signal, the digital-to-analog converter, under the control of the control module, uses the mixing characteristics to generate a synthesized signal, namely the target microwave frequency signal. The cold atom microwave clock microwave generator employs digital circuit processing to directly generate the target microwave frequency signal. The amplitude of this signal is primarily determined by the temperature characteristics of the reference voltage of the digital-to-analog converter (DAC). The temperature coefficient of this reference voltage is typically a few ppm / ℃, a hundredfold improvement over existing technologies (generally 1000–2000 ppm / ℃). This significantly enhances the microwave source's immunity to ambient temperature and its anti-interference capabilities, reducing the microwave signal's sensitivity to temperature. Consequently, it reduces the sensitivity of the output signal's stability after the clock's closed-loop locking is to ambient temperature, improving the overall clock's stability and robustness, and ensuring the long-term performance retention of the cold atom clock. Furthermore, the cold atom microwave clock microwave generator features a simple microwave circuit structure, improving microwave source reliability, low cost, and easy operation.

[0030] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and accompanying drawings. Attached Figure Description

[0031] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a schematic diagram of the structure of a cold atom microwave clock microwave generating device according to an embodiment of the present invention;

[0033] Figure 2 This is a flowchart of a cold atom microwave clock microwave generation method according to an embodiment of the present invention;

[0034] Reference numerals: 1: High-stability voltage source, 2: Reference clock signal generation module, 21: Signal source, 22: Dielectric resonant oscillator, 3: Control module, 31: Control unit, 32: Read-only memory, 33: Communication port, 4: Digital-to-analog converter. Detailed Implementation

[0035] To address the technical problem that the temperature characteristics of microwave signals from cold atom clocks are poor and cannot meet the long-term stability requirements of cold atom microwave clocks, a microwave generation device and method for cold atom microwave clocks are provided.

[0036] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Furthermore, the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0037] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of the embodiments of the present invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein.

[0038] Figure 1 This is a schematic diagram of the structure of a cold atom microwave clock microwave generating device according to an embodiment of the present invention. See also Figure 1 The cold atom microwave clock microwave generating device includes: a high-stability voltage source 1, electrically connected to a digital-to-analog converter 4 (DAC), serving as a reference voltage source for the DAC 4 to generate a reference voltage; a reference clock signal generation module 2, electrically connected to the DAC 4, used to generate a reference clock signal for the DAC 4; and a control module 3, electrically connected to the DAC 4, used to control the output frequency or output amplitude of the DAC 4. The DAC 4, based on the reference clock signal and under the control of the control module, utilizes mixing characteristics to generate a synthesized signal, i.e., the target microwave frequency signal.

[0039] Specifically, the reference clock signal generation module 2 includes: a signal source 21 for generating a clock signal; and a dielectric resonant oscillator 22 electrically connected to the signal source 21 for outputting a frequency signal, wherein the frequency signal is locked onto the clock signal and serves as the reference clock signal for the digital-to-analog converter 4.

[0040] Specifically, the control module 3 includes: a control unit 31 for generating control words; and a read-only memory (ROM) 32, one end of which is electrically connected to the control unit 31 and the other end of which is electrically connected to the digital-to-analog converter 4. The ROM sets the memory parameters of the read-only memory based on the control words and outputs a control data stream, which is used to control the output frequency or output amplitude of the digital-to-analog converter 4.

[0041] Specifically, the control unit 31 is also electrically connected to the dielectric resonant oscillator 22 to control the output frequency signal of the dielectric resonant oscillator 22.

[0042] Furthermore, the control module 3 also includes a communication port 33, which is electrically connected to the control unit 31 and is used to communicate with a host computer (such as a computer) to transmit control commands.

[0043] Specifically, the high-stability voltage source 1 is a DC power supply capable of providing accurate, low-ripple, and highly stable DC voltage output.

[0044] Specifically, the dielectric resonant oscillator 22 has characteristics such as high stability and low noise, and its output frequency signal is a high-frequency signal.

[0045] Specifically, the digital-to-analog converter 4 is a DAC chip DAC39RF10 (TI), with a working bit width of 16 bits.

[0046] According to signal processing theory, the response envelope characteristics of the sin(x) / x function (i.e., the sinc function) are mainly the main lobe characteristics and the side lobe characteristics. In the main lobe characteristics, the main lobe amplitude reaches a maximum value of 1 at x = 0, and shows an oscillating decay trend as |x| increases. In the side lobe characteristics, the amplitude of the first side lobe is about -13.26dB (relative to the main lobe peak), corresponding to x≈±1.43π. The side lobe decay rate decreases with increasing frequency at a rate of about 1 / x. The polarity of adjacent side lobes changes alternately. The typical side lobe peak position appears at x = (n+0.5)π (n is a non-zero integer), and the absolute value of the amplitude is about |2 / ((2n+1)π)|. When n = 3, the side lobe amplitude is about -20.8dB.

[0047] Based on this theory, in this embodiment, to meet the final requirement of a 6834.682610MHz microwave signal for the rubidium-based cold atom microwave clock, the reference clock signal frequency of the digital-to-analog converter 4 is 2500MHz, and the control module 3 controls the output frequency of the digital-to-analog converter 4 to be 665.31739MHz. The frequency of the synthesized signal when n=3 is: 3×2500-665.31739=6834.682610MHz, which is the target microwave frequency signal. If the amplitude of the reference clock signal is -1dBm, the maximum amplitude of the target microwave frequency signal can be -21.8dBm, meeting the requirements of the cold atom microwave clock.

[0048] In summary, the cold atom microwave clock microwave generating device provided in the embodiments of the present invention employs a high-stability voltage source 1, a reference clock signal generation module 2, a control module 3, and a digital-to-analog converter 4. The high-stability voltage source 1 generates a reference voltage for the digital-to-analog converter 4, the reference clock signal generation module 2 generates a reference clock signal for the digital-to-analog converter 4, and the control module 3 controls the output frequency or output amplitude of the digital-to-analog converter. Based on the reference clock signal, the digital-to-analog converter, under the control of the control module, uses the mixing characteristics to generate a synthesized signal, i.e., the target microwave frequency signal. The cold atom microwave clock microwave generator employs digital circuit processing to directly generate the target microwave frequency signal. The amplitude of this signal is primarily determined by the temperature characteristics of the reference voltage of the digital-to-analog converter 4. The temperature coefficient of this reference voltage is typically a few ppm / ℃, a hundred times higher than the temperature characteristics of existing technologies (generally 1000–2000 ppm / ℃). This significantly improves the microwave source's immunity to ambient temperature and its anti-interference capability, reducing the microwave signal's sensitivity to ambient temperature. Consequently, it reduces the sensitivity of the output signal's stability after the clock's closed-loop locking is to ambient temperature, improving the overall clock's stability and robustness, and ensuring the long-term performance retention of the cold atom clock. Furthermore, the cold atom microwave clock microwave generator has a simple microwave circuit structure, improving microwave source reliability, and is low-cost and easy to operate.

[0049] This invention also provides a method for generating microwaves using a cold atom microwave clock, comprising the following steps:

[0050] Generate the reference voltage for the digital-to-analog converter;

[0051] Generate a reference clock signal for the digital-to-analog converter;

[0052] Control the output frequency or output amplitude of the digital-to-analog converter;

[0053] The digital-to-analog converter generates a synthesized signal, i.e., the target microwave frequency signal, based on a reference clock signal and using mixing characteristics.

[0054] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0055] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A cold atom microwave clock microwave generating device, characterized in that, include: A high-stability voltage source (1) is electrically connected to the digital-to-analog converter (4) and serves as a reference voltage source for the digital-to-analog converter (4) to generate the reference voltage of the digital-to-analog converter (4); The reference clock signal generation module (2) is electrically connected to the digital-to-analog converter (4) and is used to generate the reference clock signal of the digital-to-analog converter (4); The control module (3) is electrically connected to the digital-to-analog converter (4) and is used to control the output frequency or output amplitude of the digital-to-analog converter (4); The digital-to-analog converter (4), based on the reference clock signal, generates a synthesized signal, namely the target microwave frequency signal, by utilizing the mixing characteristics under the control of the control module.

2. The microwave generating device for a cold atom microwave clock according to claim 1, characterized in that, The reference clock signal generation module (2) includes: Signal source (21) is used to generate clock signals; A dielectric resonant oscillator (22) is electrically connected to the signal source (21) and is used to output a frequency signal, which is locked to the clock signal and serves as the reference clock signal for the digital-to-analog converter (4).

3. The cold atom microwave clock microwave generating device according to claim 1, characterized in that, The control module (3) includes: Control unit (31) is used to generate control words; The read-only memory (32) is electrically connected to the control unit (31) at one end and to the digital-to-analog converter (4) at the other end. The memory parameters of the read-only memory are set based on the control word, and the control data stream is output. The control data stream is used to control the output frequency or output amplitude of the digital-to-analog converter (4).

4. The microwave generating device for a cold atom microwave clock according to claim 3, characterized in that, The control unit (31) is also electrically connected to the dielectric resonator (22) for controlling the dielectric resonator (22) to output the frequency signal.

5. The microwave generating device for a cold atom microwave clock according to claim 3, characterized in that, The control module (3) further includes a communication port (33), which is electrically connected to the control unit (31) and is used to communicate with the host computer to transmit control commands.

6. The cold atom microwave clock microwave generating device according to claim 1, characterized in that, The high-stability voltage source (1) is a DC power supply.

7. The microwave generating device for a cold atom microwave clock according to claim 2, characterized in that, The frequency signal is a high-frequency signal.

8. The cold atom microwave clock microwave generating device according to claim 1, characterized in that, The digital-to-analog converter (4) has a working bit width of 16 bits.

9. The cold atom microwave clock microwave generating device according to claim 1, characterized in that, The frequency of the reference clock signal is 2500MHz, the control module (3) controls the output frequency of the digital-to-analog converter (4) to be 665.31739MHz, and the frequency of the target microwave frequency signal is 6834.682610MHz.

10. A method for generating microwaves in a cold atom microwave clock, characterized in that, Includes the following steps: Generate the reference voltage for the digital-to-analog converter; Generate a reference clock signal for the digital-to-analog converter; Control the output frequency or output amplitude of the digital-to-analog converter; The digital-to-analog converter generates a synthesized signal, namely the target microwave frequency signal, based on the reference clock signal and using the mixing characteristics.

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