CN110824888A - Signal acquisition method and device applied to atomic fountain clock - Google Patents
Signal acquisition method and device applied to atomic fountain clock Download PDFInfo
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- CN110824888A CN110824888A CN201810905020.1A CN201810905020A CN110824888A CN 110824888 A CN110824888 A CN 110824888A CN 201810905020 A CN201810905020 A CN 201810905020A CN 110824888 A CN110824888 A CN 110824888A
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- G04F—TIME-INTERVAL MEASURING
- G04F5/00—Apparatus for producing preselected time intervals for use as timing standards
- G04F5/14—Apparatus for producing preselected time intervals for use as timing standards using atomic clocks
Abstract
The invention provides a signal acquisition method and a signal acquisition device applied to an atomic fountain clock. The device includes: the laser frequency shift unit is used for generating ultrastable microwaves according to ultrastable lasers, the input end of the ultrastable microwave frequency conversion unit is connected with the output end of the laser frequency shift unit, the input end of the standard signal acquisition unit is connected with the output end of the ultrastable microwave frequency conversion unit, the input end of the long-term stability acquisition unit is connected with the output end of the standard signal acquisition unit, and the input end of the excitation signal acquisition unit is respectively connected with the output end of the standard signal acquisition unit and the output end of the ultrastable microwave frequency conversion unit. The frequency drift of the ultrastable laser is compensated according to the signal output by the long-term stability obtaining unit, so that the long-term stability of the ultrastable laser is improved, and the long-term stability of the excitation signal is improved.
Description
Technical Field
The invention relates to the technical field of time measurement, in particular to a signal acquisition method and device applied to an atomic fountain clock.
Background
In 1967, the thirteenth international convention for the determination of seconds changed the definition of seconds from astronomical seconds to atomic seconds, i.e. "seconds are the time during which atoms of Cesium (Cesium, abbreviated as Cs) -133 were radiated for 9192631770 cycles at two hyperfine energy levels corresponding to the ground state at 0K (Kelvin)". The international commission on metrology in 1997 confirmed that the cesium atom is in the "ground state 0K temperature" as defined above. From this point on, a laboratory cesium atom fountain clock becomes a time frequency measuring reference device. The laboratory cesium atom fountain clock utilizes transition spectral lines of electrons in cesium atoms at two energy levels to carry out frequency discrimination on an excitation signal, and then locks the frequency of the excitation signal on the central frequency of the transition spectral lines through a frequency locking loop, so that second-defined reproduction is realized. Therefore, the performance of the excitation signal is extremely important for the reproduction seconds definition.
In the prior art, an excitation signal is mainly generated by a photoproduction microwave method, the photoproduction microwave method is used for transmitting the stability of ultrastable laser to a microwave signal through an optical frequency comb, and the short-term stability of the generated excitation signal can reach 10-14. The excitation signal generated by the above method is inferior in long-term stability.
Disclosure of Invention
The invention provides a signal acquisition method and a signal acquisition device applied to an atomic fountain clock, which are used for generating an excitation signal with long-term stability.
In a first aspect, the present invention provides a signal acquisition apparatus, comprising:
the device comprises a laser frequency shift unit, an ultra-stable microwave frequency conversion unit, a standard signal acquisition unit, a long-term stability acquisition unit and an excitation signal acquisition unit;
the laser frequency shift unit is used for generating an ultrastable microwave according to the ultrastable laser;
the input end of the ultra-stable microwave frequency conversion unit is connected with the output end of the laser frequency shift unit, and the ultra-stable microwave frequency conversion unit is used for generating high-frequency ultra-stable microwaves with the same stability as the ultra-stable microwaves according to the ultra-stable microwaves;
the input end of the standard signal obtaining unit is connected with the output end of the ultra-stable microwave frequency conversion unit, and the standard signal obtaining unit is used for generating a standard high-frequency signal according to the high-frequency ultra-stable microwave;
the input end of the long-term stability obtaining unit is connected with the output end of the standard signal obtaining unit, and the long-term stability obtaining unit is used for compensating the frequency drift of the ultrastable laser according to the standard high-frequency signal;
the input end of the excitation signal obtaining unit is respectively connected with the output end of the standard signal obtaining unit and the output end of the ultra-stable microwave frequency conversion unit, and the excitation signal obtaining unit is used for generating an excitation signal according to the standard high-frequency signal and the high-frequency ultra-stable microwave.
Further, the laser frequency shift unit includes: the device comprises an acousto-optic modulator, an optical frequency comb, a first direct digital frequency synthesizer and a first hydrogen clock;
the acousto-optic modulator is used for shifting the frequency of the ultrastable laser and locking the optical frequency comb on the frequency-shifted ultrastable laser to generate the ultrastable microwave;
the driving signal used by the radio frequency source of the acousto-optic modulator is provided by the first direct digital frequency synthesizer, and the first direct digital frequency synthesizer is controlled by the error signal output by the long-term stability obtaining unit and the first hydrogen clock.
Further, the ultra-stable microwave frequency conversion unit comprises a first dielectric oscillator.
Further, the standard signal obtaining unit includes: the system comprises a constant temperature crystal oscillator, a first processing unit, a second medium oscillator, a beat frequency unit, a phase frequency and phase discrimination unit, a filter, a frequency synthesizer and a second hydrogen clock;
the input end of the second dielectric oscillator is connected with the output end of the constant-temperature crystal oscillator, and the second dielectric oscillator is used for generating a first microwave signal according to the standard high-frequency signal output by the constant-temperature crystal oscillator;
the beat frequency unit is used for carrying out beat frequency processing on the high-frequency ultrastable microwave and the first microwave signal to obtain a low-frequency signal, and the low-frequency signal is transmitted to the frequency and phase discrimination unit through the filter;
the input end of the phase frequency and phase detection unit is also connected with the frequency synthesizer, and the phase frequency and phase detection unit is used for performing phase frequency and phase detection processing on the signal output by the filter and the signal output by the frequency synthesizer to obtain a first error signal; said frequency synthesizer is served by said second hydrogen clock;
the input end of the first processing unit is connected with the output end of the phase frequency and phase discrimination unit, the first processing unit is used for filtering, proportionally amplifying and integrating the first error signal, and sending the processed first error signal to the constant-temperature crystal oscillator, so that the constant-temperature crystal oscillator generates the standard high-frequency signal according to the processed first error signal.
Further, the frequency of the standard high-frequency signal is 100 MHz.
Further, the long-term stability obtaining unit includes: the phase discrimination unit, the third hydrogen clock and the second processing unit;
the phase discrimination unit is used for performing phase discrimination processing on the standard high-frequency signal and a signal output by the third hydrogen clock to generate a second error signal;
the second processing unit is used for performing filtering, proportional amplification and integral processing on the second error signal to obtain a processed second error signal, and the second error signal is used for compensating the frequency drift of the ultrastable laser.
Further, the excitation signal obtaining unit includes: the first single-side mixer, the second single-side mixer, the frequency synthesis unit, the power attenuator, the power divider, the phase shifter, the interference switch, the fourth hydrogen clock and the second direct digital frequency synthesizer;
the power divider is used for amplifying and distributing power of the standard high-frequency signal; the output end of the power divider is respectively connected with the power attenuator and the phase shifter;
the power attenuator is used for performing power attenuation on the received signal and transmitting the attenuated signal to the frequency synthesis unit;
the phase shifter is used for performing phase shifting processing on the received signal and transmitting the phase-shifted signal to the frequency synthesis unit through the interference switch;
the input end of the first single-side mixer is respectively connected with the output end of the frequency synthesis unit and the output end of the ultra-stable microwave frequency conversion unit, and the first single-side mixer is used for performing frequency mixing processing on the high-frequency ultra-stable microwave and the signal output by the frequency synthesis unit to obtain a first mixing signal;
the input end of the second single-side mixer is connected to the output end of the first single-side mixer and the output end of the second direct digital frequency synthesizer served by the fourth clock, respectively, and the second single-side mixer is configured to generate the excitation signal according to the first mixing signal and a signal output by the second direct digital frequency synthesizer.
Furthermore, the first hydrogen clock, the second hydrogen clock, the third hydrogen clock and the fourth hydrogen clock are the same hydrogen clock.
In a second aspect, the present invention provides a signal acquiring method applied to the signal acquiring apparatus in the first aspect, the method including:
generating an ultrastable microwave according to the ultrastable laser by the laser frequency shift unit;
generating high-frequency ultra-stable microwaves with the same stability as the ultra-stable microwaves according to the ultra-stable microwaves by the ultra-stable microwave frequency conversion unit;
generating a standard high-frequency signal according to the high-frequency ultra-stable microwave through the standard signal obtaining unit;
compensating the frequency drift of the ultrastable laser by the long-term stability obtaining unit according to the standard high-frequency signal;
and generating an excitation signal according to the standard high-frequency signal and the high-frequency ultra-stable microwave by the excitation signal obtaining unit.
In a third aspect, the present invention provides an atomic fountain clock, where the atomic fountain clock discriminates a frequency of an excitation signal by using a transition spectral line of electrons in an atom at two energy levels, and locks the frequency of the excitation signal acquired by the signal acquisition device according to the first aspect to a central frequency of the transition spectral line through a frequency locking loop, so as to implement second-defined reproduction.
Further, the atomic fountain clock comprises the signal acquisition device.
The invention provides a signal acquisition method and a signal acquisition device applied to an atomic fountain clock, wherein the device comprises the following steps: the laser frequency shift unit is used for generating ultrastable microwaves according to ultrastable lasers, the input end of the ultrastable microwave frequency conversion unit is connected with the output end of the laser frequency shift unit, the ultrastable microwave frequency conversion unit is used for generating high-frequency ultrastable microwaves with the same stability as the ultrastable microwaves according to the ultrastable microwaves, the input end of the standard signal obtaining unit is connected with the output end of the ultrastable microwave frequency conversion unit, the standard signal obtaining unit is used for generating standard high-frequency signals according to the high-frequency ultrastable microwaves, the input end of the long-term stability obtaining unit is connected with the output end of the standard signal obtaining unit, the long-term stability obtaining unit is used for compensating frequency drift of the ultrastable lasers according to the standard high-frequency signals, and the input end of the excitation signal obtaining unit is respectively connected with the output end of the standard signal obtaining unit and the frequency variation unit of the ultrastable microwaves The output end of the switching unit is connected, and the excitation signal obtaining unit is used for generating an excitation signal according to the standard high-frequency signal and the high-frequency ultra-stable microwave.
The invention has the beneficial effects that: the device compensates the frequency drift of the ultrastable laser according to the signal output by the long-term stability obtaining unit, so that the long-term stability of the ultrastable laser is improved, and the long-term stability of the excitation signal and the accuracy of atomic transition are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, 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 schematic structural diagram of a first embodiment of a signal acquisition device according to the present invention;
fig. 2 is a schematic structural diagram of a second embodiment of a signal acquisition device according to the present invention;
fig. 3 is a schematic flowchart of a first embodiment of a signal acquisition method according to the present invention;
fig. 4 is a schematic structural diagram of a first embodiment of an atomic fountain clock provided by 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.
Fig. 1 is a schematic structural diagram of a first embodiment of a signal acquisition device according to the present invention. As shown in fig. 1, the apparatus 10 of the present embodiment includes: the device comprises a laser frequency shift unit 11, an ultra-stable microwave frequency conversion unit 12, a standard signal obtaining unit 13, a long-term stability obtaining unit 14 and an excitation signal obtaining unit 15.
The laser frequency shift unit 11 is configured to generate an ultrastable microwave by using an optical frequency comb according to the ultrastable laser.
Ultrastable laser, also called ultrashort linewidth laser, refers to that the central frequency of a common single-frequency laser is locked on the resonance frequency of an ultrastable fabry-perot cavity (ultrastable cavity for short) by a laser frequency stabilizing technology, so as to obtain laser with linewidth less than 1 Hz.
The laser frequency shift unit 11 shifts the frequency of the ultrastable laser and then generates ultrastable microwaves by using an optical frequency comb.
The input end of the ultrastable microwave frequency conversion unit 12 is connected with the output end of the laser frequency shift unit 11, and the ultrastable microwave frequency conversion unit 12 is used for generating high-frequency ultrastable microwaves with the same stability as the ultrastable microwaves according to the ultrastable microwaves.
For example, the ultrastable microwave frequency conversion unit 12 converts the frequency of the ultrastable microwave output from the laser frequency shift unit 11 to obtain a high-frequency ultrastable microwave. Since the ultrastable microwave frequency conversion unit 12 only converts the frequency of the ultrastable microwave and does not change other characteristics of the ultrastable microwave, the stability of the obtained high-frequency ultrastable microwave is the same as that of the ultrastable microwave.
Further, the ultrastable microwave frequency transforming unit 12 transmits the generated high-frequency ultrastable microwave signal to the standard signal obtaining unit 13. The input end of the standard signal obtaining unit 13 is connected with the output end of the ultra-stable microwave frequency conversion unit 12, and the standard signal obtaining unit 13 is used for generating a standard high-frequency signal according to the high-frequency ultra-stable microwave. The standard signal obtaining unit 13 generates a standard high frequency signal from the received high frequency ultra-stable microwave signal. Since the standard high-frequency signal is generated from the high-frequency hyperstable microwave, the standard high-frequency signal has the same stability as the high-frequency hyperstable microwave signal. The stability of the ultrastable microwave is transmitted to the high-frequency ultrastable microwave by a frequency conversion method, and then the stability of the high-frequency ultrastable microwave is transmitted to the standard high-frequency signal, so that the standard high-frequency signal is ensured to have good stability.
Alternatively, the frequency of the standard high frequency signal may be 100 MHz. Of course, the frequency of the standard high-frequency signal may also be 5MHz or 10MHz, and the frequency of the standard high-frequency signal may be determined according to specific requirements.
It should be noted that the standard signal obtaining unit 13 provides a direct interface for calibrating hydrogen clock timing. Specifically, the standard high-frequency signal generated by the standard signal obtaining unit 13 can be directly used for calibrating hydrogen clock timing, thereby providing a reliable solution for establishing a time frequency reference.
The input end of the long-term stability obtaining unit 14 is connected with the output end of the standard signal obtaining unit 13, and the long-term stability obtaining unit 14 is used for compensating the frequency drift of the ultrastable laser according to the standard high-frequency signal. Due to the characteristic that the frequency of the ultrastable laser has a long-term drift, the long-term stability of the ultrastable microwave generated by the laser frequency shift unit 11 according to the ultrastable laser is poor. Therefore, the long-term stability obtaining unit 14 generates an error signal from the standard high-frequency signal, and compensates the frequency drift of the ultrastable laser by the error signal, thereby improving the long-term stability of the ultrastable laser. Further, the long-term stability of the ultrastable microwave is improved.
The input end of the excitation signal obtaining unit 15 is connected to the output end of the standard signal obtaining unit 13 and the output end of the ultra-stable microwave frequency transforming unit 12, respectively, and the excitation signal obtaining unit 15 is configured to generate an excitation signal according to the standard high-frequency signal and the high-frequency ultra-stable microwave. Among them, the excitation signal generated by the excitation signal obtaining unit 15 has the stability of the high frequency ultrastable microwave because the excitation signal is generated according to the standard high frequency signal and the high frequency ultrastable microwave.
Further, since the error signal input by the long-term stability obtaining unit 14 overcomes the long-term drift characteristic of the ultrastable laser, and improves the long-term stability of the ultrastable microwave, the long-term stability of the high-frequency ultrastable microwave is further improved, thereby improving the long-term stability of the excitation signal.
In this embodiment, the apparatus includes: the device comprises a laser frequency shift unit, an ultra-stable microwave frequency conversion unit, a standard signal acquisition unit, a long-term stability acquisition unit and an excitation signal acquisition unit. The laser frequency shifting unit is used for generating ultrastable microwaves according to ultrastable lasers, the input end of the ultrastable microwave frequency conversion unit is connected with the output end of the laser frequency shifting unit, the ultrastable microwave frequency conversion unit is used for generating high-frequency ultrastable microwaves with the same stability as the ultrastable microwaves according to the ultrastable microwaves, the input end of the standard signal obtaining unit is connected with the output end of the ultrastable microwave frequency conversion unit, the standard signal obtaining unit is used for generating standard high-frequency signals according to the high-frequency ultrastable microwaves, the input end of the long-term stability obtaining unit is connected with the output end of the standard signal obtaining unit, the long-term stability obtaining unit is used for compensating frequency drift of the ultrastable lasers according to the standard high-frequency signals, the input end of the excitation signal obtaining unit is connected with the output end of the standard signal obtaining unit and the output end of the ultrastable microwave frequency conversion unit, and the excitation signal obtaining unit is used for generating excitation. The device compensates the frequency drift of the ultrastable laser according to the signal output by the long-term stability obtaining unit, so that the long-term stability of the ultrastable laser is improved, and the long-term stability of the excitation signal and the accuracy of atomic transition are improved.
The technical solution of the embodiment of the apparatus shown in fig. 1 is described in detail below by using a specific embodiment.
Fig. 2 is a schematic structural diagram of a second embodiment of a signal obtaining apparatus according to the present invention, and as shown in fig. 2, an apparatus 20 of the present embodiment includes: the device comprises a laser frequency shift unit 11, an ultra-stable microwave frequency conversion unit 12, a standard signal obtaining unit 13, a long-term stability obtaining unit 14 and an excitation signal obtaining unit 15.
Specifically, the laser frequency shift unit 11 may include: an acousto-optic modulator 111, an optical frequency comb 112, a first direct digital frequency synthesizer 113, and a first hydrogen clock 114.
The acousto-optic modulator 111 is used for shifting the frequency of the ultrastable laser, and locking the optical frequency comb 112 to the frequency-shifted ultrastable laser to generate the ultrastable microwave.
In addition, a drive signal used by the radio frequency source of the acousto-optic modulator 111 is supplied from a first direct digital frequency synthesizer 113, and the first direct digital frequency synthesizer 113 is controlled by an error signal output from the long-term stability obtaining unit and a first hydrogen clock 114.
Specifically, the first direct digital frequency synthesizer 113 frequency-synthesizes the error signal output from the long-term stability obtaining unit 14 and the signal output from the first hydrogen clock 114, thereby generating a drive signal for the radio frequency source of the acousto-optic modulator 111. The acousto-optic modulator 111 shifts the frequency of the ultrastable laser according to the driving signal, and locks the optical frequency comb 112 on the frequency-shifted ultrastable laser to generate the ultrastable microwave.
Further, the ultra-stable microwave frequency conversion unit 12 may include a first dielectric oscillator (DRO) 121. Specifically, an input end of the first dielectric oscillator 121 is an input end of the ultrastable microwave frequency varying unit 12, and an output end of the first dielectric oscillator 121 is an output end of the ultrastable microwave frequency varying unit 12. The first dielectric oscillator 121 is configured to generate a high-frequency ultrastable microwave having a frequency close to the excitation signal and having the same stability as the ultrastable microwave according to the ultrastable microwave.
Optionally, the first dielectric oscillator 121 obtains the high-frequency ultrastable microwave by converting the frequency of the ultrastable microwave. The range of frequency conversion can be determined according to actual requirements.
On the basis of the above, the standard signal obtaining unit 13 may include: the system comprises a constant temperature crystal oscillator 131, a first processing unit 132, a second medium oscillator 133, a beat frequency unit 134, a phase frequency detection unit 135, a filter 136, a frequency synthesizer 137 and a second hydrogen clock 138.
Specifically, an input end of the second dielectric oscillator 133 is connected to an output end of the oven controlled crystal oscillator 131, and the second dielectric oscillator 133 is configured to generate the first microwave signal according to the standard high-frequency signal output by the oven controlled crystal oscillator 131. Alternatively, the second dielectric oscillator 133 obtains the first microwave signal by converting the frequency of the standard high-frequency signal.
The beat frequency unit 134 is configured to perform beat frequency processing on the high-frequency ultrastable microwave and the first microwave signal to obtain a low-frequency signal, and the low-frequency signal is transmitted to the frequency and phase discrimination unit 135 through the filter 136. That is, the low frequency signal is the difference between the ultrastable microwave and the first microwave signal.
Alternatively, the beat frequency unit 134 may be a mixer, which is capable of obtaining a difference signal of the two input signals, that is, the frequency of the low frequency signal is equal to the frequency of the first microwave signal minus the frequency of the high frequency ultrastable microwave.
The input end of the phase frequency and phase detection unit 135 may be further connected to the frequency synthesizer 137, and the phase frequency and phase detection unit 135 is configured to perform phase frequency and phase detection on the signal output by the filter 136 and the signal output by the frequency synthesizer 137 to obtain a first error signal; frequency synthesizer 137 is served by a second clock 138.
The input end of the first processing unit 132 is connected to the output end of the phase frequency and phase detection unit 135, and the first processing unit 132 is configured to perform filtering, proportional amplification, integration and other processing on the first error signal, and send the processed first error signal to the constant temperature crystal oscillator 131, so that the constant temperature crystal oscillator 131 generates a standard high-frequency signal according to the processed first error signal.
The stability of the ultra-stable microwave is better than 10-14And because the frequency of the ultrastable microwave output by the optical frequency comb 112 is controlled by the cavity length of the resonator, the adjustable range of the frequency value of the output repetition frequency is small for the optical frequency comb 112, and the frequency of the output ultrastable microwave may not be directly converted to the frequency of the standard high-frequency signal. Therefore, the ultrastable microwave is first converted into high-frequency ultrastable microwave without loss, and further, the low-frequency signal is obtained through beat frequency processing. Since the frequency of the low-frequency signal differs from the frequency of the high-frequency hyperstable microwave by 2 orders or more, the frequency conversion of the hyperstable microwave can be realized by locking the low-frequency signal.
The standard signal obtaining unit 13 can complete the locking of the standard high-frequency signal generated by the constant-temperature crystal oscillator 131 to the ultra-stable microwave through the above process.
Further, the long-term stability obtaining unit 14 may include: a phase detection unit 141, a third hydrogen clock 142 and a second processing unit 143.
The phase detection unit 141 may be configured to perform phase detection on the standard high-frequency signal and a signal output by the third hydrogen clock 142, and generate a second error signal.
The second processing unit 143 may be configured to perform filtering, proportional amplification, and integral processing on the second error signal to obtain a processed second error signal, where the second error signal is used to compensate for frequency drift of the ultrastable laser.
The second processing unit 143 may perform filtering, proportional amplification, integration, and other processing on the second error signal, so as to eliminate interference of the noise signal, and improve accuracy of the second error signal, thereby accurately compensating for frequency drift of the ultrastable laser.
Specifically, the constant temperature crystal oscillator 131 performs frequency discrimination on a standard high frequency signal generated after being locked to the ultrastable micro-wave and a comparison signal output by the third hydrogen clock 142, so as to generate a second error signal, the second processing unit 143 performs filtering, proportional amplification, integration and other processing on the second error signal, feeds the processed second error signal back to the first direct digital frequency synthesizer 113, and controls the frequency of an output signal of the first direct digital frequency synthesizer 113, so that the frequency drift of the ultrastable laser is accurately compensated, and the long-term stability of the ultrastable laser is improved.
The excitation signal obtaining unit 15 may include: a first single-side mixer 151, a second single-side mixer 152, a frequency synthesis unit 153, a power attenuator 154, a power divider 155, a phase shifter 156, an interference switch 157, a fourth clock 158, and a second direct digital frequency synthesizer 159.
The power divider 155 is configured to amplify and distribute power of the standard high-frequency signal. The output of the power divider 155 is connected to the power attenuator 154 and the phase shifter 156, respectively.
In practical applications, the power divider 155 may be an active power divider 155, and may amplify and distribute the power of the standard high-frequency signal, one of the two distributed signals is output to the power attenuator 154, and the other is output to the phase shifter 156.
The power attenuator 154 is configured to perform power attenuation on the received signal and transmit the attenuated signal to the frequency synthesizing unit 153. The power of the attenuated signal is at a level acceptable to the frequency synthesizing unit 153.
The phase shifter 156 is configured to perform a phase shift process on the received signal, and transmit the phase-shifted signal to the frequency synthesizing unit 153 through the interference switch 157. Optionally, phase shifter 156 phase shifts the received signal by 90 °.
And a frequency synthesizing unit 153 for signal-synthesizing the signals from the power attenuator 154 and the interference switch 157. Alternatively, the interference switch 157 is turned on and off by a control signal output from a PC. When the interference switch 157 is turned on, the signals at the two input ends of the frequency synthesis unit 153 cancel each other, and the frequency synthesis unit 153 outputs no signal. When the interference switch 157 is turned off, the signal output from the phase shifter 156 is cut off, and the frequency synthesizing unit 153 outputs the signal output from the power attenuator 154.
The input end of the first single-side mixer 151 is connected to the output end of the frequency synthesizing unit 153 and the output end of the ultra-stable microwave frequency transforming unit 12, and the first single-side mixer 151 is configured to perform frequency mixing processing on the high-frequency ultra-stable microwave and the signal output by the frequency synthesizing unit 153 to obtain a first mixed signal. Specifically, the input end of the first single-side mixer 151 is connected to the output end of the frequency synthesizing unit 153 and the output end of the first dielectric oscillator 121, respectively.
The input terminal of the second single-side mixer 152 is connected to the output terminal of the first single-side mixer 151 and the output terminal of the second direct digital frequency synthesizer 159 served by the fourth clock 158, respectively, and the second single-side mixer 152 is configured to generate the excitation signal according to the first mixed signal and the signal output by the second direct digital frequency synthesizer 159.
When the interference switch 157 is turned on, the phases of the signals output by the power attenuator 154 and the phase shifter 156 are opposite and cancel each other out, the frequency synthesizer outputs no signal, so that the frequency difference between the generated signal and the required excitation signal is large, and the excitation signal has no effect on the atomic fountain clock, thereby realizing the effect of turning off the excitation signal. When the interference switch 157 is turned off, the signal output from the phase shifter 156 is cut off, the frequency synthesizing unit 153 outputs the signal output from the power attenuator 154, the first single-side mixer 151 mixes the received high-frequency ultra-stable microwave with the signal output from the frequency synthesizing unit 153 to obtain a first mixed signal, and the second single-side mixer 152 mixes the first mixed signal with the output signal of the second direct digital frequency synthesizer 159, which is served by the fourth hydrogen clock 158, to generate the excitation signal. The excitation signal has not only a short-term stability but also a long-term stability.
Alternatively, the first hydrogen clock 114, the second hydrogen clock 138, the third hydrogen clock 142, and the fourth hydrogen clock 158 may be the same hydrogen clock.
The laser frequency shift unit in the embodiment shifts the frequency of the ultrastable laser according to the error signal output by the long-term stability acquisition unit and the signal output by the first hydrogen clock, so that the characteristic of long-term frequency drift of the ultrastable laser is overcome, the long-term stability of the ultrastable laser is improved, and meanwhile, the real-time comparison with the hydrogen clock can be realized, so that the long-term stability of the excitation signal and the accuracy of atomic transition are improved. Further, the device in this embodiment provides a direct interface for calibrating the hydrogen clock timekeeping, and the standard high-frequency signal generated by the standard signal obtaining unit can be directly used for calibrating the hydrogen clock timekeeping, thereby providing a reliable solution for establishing a time frequency reference.
Illustratively, the excitation signal generated by the device in the above embodiment is applied to a cesium atom fountain clock, and the signal acquisition device of the present invention is described in detail by taking cesium atom transition of 9192631770Hz as an example.
Referring to fig. 2, the frequency of the optical frequency comb is shifted by 40MHz by the acousto-optic modulator, and the radio frequency source used to drive the acousto-optic modulator is served by a hydrogen clock because the stability of the ultrastable laser is high. The optical comb repetition frequency f in this embodimentr221MHz, and outputs 42 times of frequency after passing through the first dielectric oscillator, i.e. high-frequency ultrastable microwave n frThe frequency of the first microwave signal omega is 9282MHz, the first microwave signal omega with the frequency of 9300MHz is output after the high-frequency ultra-stable microwave and the 100MHz output by the constant-temperature crystal oscillator pass through the second medium oscillator1Beat frequency to obtain low frequency signal omega2，Ω2Has a frequency of 18MHz, and obtains a low-frequency signal omega of 18MHz2Then with a signal omega with a frequency of 18MHz output by a frequency synthesizer served by a hydrogen clock3And performing frequency discrimination and phase discrimination to obtain a first error signal, and performing feedback control on the first error signal after filtering, proportional amplification and integration so as to realize that the constant-temperature crystal oscillator is locked on the ultra-stable microwave and obtain the stability of the ultra-stable microwave.
After the constant temperature crystal oscillator is locked, the stability of the output 100MHz standard high frequency signal is consistent with the ultra-stable microwave, but due to the aging problem of the ultra-stable cavity of the ultra-stable laser, the frequency of the ultra-stable laser can drift all the time, the average daily drift amount can reach the kHz magnitude, the standard high frequency signal with the 100MHz output frequency of the constant temperature crystal oscillator and the signal with the 100MHz output frequency of the hydrogen clock are subjected to frequency discrimination and phase discrimination, and then relevant filtering, proportional amplification and integral parameters are set according to the stability of the hydrogen clock and the stability of the ultra-stable microwave, so that the frequency shift amount of the ultra-stable laser by the acousto-optic modulator is controlled, the compensation of the frequency drift of the ultra-stable laser is realized, the ultra-stable microwave obtains the long-term stability of the hydrogen clock, and the 100MHz output by the constant temperature crystal oscillator correspondingly obtains the long-term stability of the hydrogen clock.
Further, after the ultra-stable microwave obtains the long-term stability of the hydrogen clock, the ultra-stable microwave directly outputs high-frequency ultra-stable microwave n x f with the frequency of 9282MHz to the first dielectric oscillatorrThe frequency of the excitation signal is converted to obtain the frequency required by the excitation signal. Firstly, a standard high-frequency signal with the frequency of 100MHz output by a constant-temperature crystal oscillator is subjected to power divider to obtain two paths of signals with the same phase, wherein one path of signals is subjected to power attenuator to realize final control on the power of an excitation signal, the other path of signals is subjected to phase shift of 90 degrees after passing through a phase shifter, and then the signals are finally synthesized with the frequency of the signals after passing through the power attenuator through an interference switch.
When the interference switch is switched off, the phase-shifted signal is cut off, the frequency of the signal output by the frequency synthesis unit is 100MHz, the frequency of the signal is mixed with the 9282MHz frequency to obtain a 9182MHz frequency signal, and the 9182MHz frequency signal is mixed with the 10.63177MHz frequency signal output by the second direct digital frequency synthesizer served by the hydrogen clock to obtain a final excitation signal, wherein the frequency of the excitation signal is 9192631770 Hz.
When the interference switch is turned on, the two signals with the frequency of 100MHz are mutually offset due to phase inversion, the output frequency of the frequency synthesis unit is 0, so that the final output frequency is 9292.63177MHz, the frequency is far away from the frequency of the driving signal required by the cesium atom fountain clock, the driving signal does not act on the cesium atom fountain clock, and the signal source is turned off.
It should be noted that, the situation of exciting other atomic transitions is similar to the situation of exciting cesium atomic transitions, and the device provided by the present invention may set corresponding parameters according to actual requirements, which is not limited by the present invention.
The above-described embodiments explain a specific structure of the signal acquisition apparatus provided by the present invention, and a method of using the signal acquisition apparatus, that is, a signal acquisition method, is described next.
Fig. 3 is a flowchart illustrating a first embodiment of a signal acquisition method according to the present invention. The method of the present embodiment is applied to the signal acquiring apparatus shown in fig. 1 and fig. 2, and as shown in fig. 3, the method of the present embodiment includes:
s301, generating the ultra-stable microwave according to the ultra-stable laser through the laser frequency shift unit.
Specifically, the laser frequency shift unit shifts the frequency of the ultrastable laser, and locks the optical frequency comb on the frequency-shifted ultrastable laser, thereby generating the ultrastable microwave.
And S302, generating high-frequency ultra-stable microwaves with the same stability as the ultra-stable microwaves according to the ultra-stable microwaves through an ultra-stable microwave frequency conversion unit.
The ultrastable microwave frequency conversion unit converts the frequency of the ultrastable microwave to generate the high-frequency ultrastable microwave. Because the frequency changing unit of the ultra-stable microwave only changes the frequency and does not change other characteristics of the ultra-stable microwave, the stability of the obtained high-frequency ultra-stable microwave is the same as that of the ultra-stable microwave.
And S303, generating a standard high-frequency signal according to the high-frequency ultra-stable microwave through a standard signal obtaining unit.
Specifically, the standard signal obtaining unit generates a standard high-frequency signal according to the high-frequency ultra-stable microwave and the feedback control signal.
And S304, compensating the frequency drift of the ultrastable laser according to the standard high-frequency signal through the long-term stability obtaining unit.
Specifically, the long-term stability obtaining unit generates an error signal according to the comparison between the standard high-frequency signal and the hydrogen clock, and transmits the error signal to the laser frequency shifting unit so as to compensate the frequency drift of the ultrastable laser.
And S305, generating an excitation signal according to the standard high-frequency signal and the high-frequency ultra-stable microwave through an excitation signal obtaining unit.
The high-frequency ultrastable microwave is obtained according to the ultrastable microwave after compensating the frequency drift, so that the long-term stability of the high-frequency ultrastable microwave is better. Optionally, the excitation signal obtaining unit performs frequency conversion on the high-frequency ultra-stable microwave and the standard high-frequency signal to generate the excitation signal.
Optionally, the driving signal source is controlled to be turned on and off by an interference switch.
For the specific structure of each unit in this embodiment, reference may be made to the foregoing embodiments, and details are not repeated here.
In this embodiment, the laser frequency shift unit generates an ultrastable microwave according to ultrastable laser, the ultrastable microwave frequency conversion unit generates a high-frequency ultrastable microwave with the same stability as the ultrastable microwave according to the ultrastable microwave, the standard signal obtaining unit generates a standard high-frequency signal according to the high-frequency ultrastable microwave, the long-term stability obtaining unit compensates for frequency drift of the ultrastable laser according to the standard high-frequency signal, and the excitation signal obtaining unit generates an excitation signal according to the standard high-frequency signal and the high-frequency ultrastable microwave. The frequency of the ultrastable laser is shifted according to the error signal output by the long-term stability acquisition unit and the signal output by the first hydrogen clock, so that the characteristic of long-term frequency drift of the ultrastable laser is overcome, the long-term stability of the ultrastable laser is improved, and meanwhile, the real-time comparison with the hydrogen clock can be realized, so that the long-term stability of the excitation signal and the accuracy of atomic transition are improved. Furthermore, a direct interface is provided for calibrating the hydrogen clock timekeeping, and the standard high-frequency signal generated by the standard signal obtaining unit can be directly used for calibrating the hydrogen clock timekeeping, so that a reliable solution is provided for establishing a time frequency reference.
Fig. 4 is a schematic structural diagram of a first embodiment of an atomic fountain clock provided by the present invention. The atomic fountain clock 40 uses electrons in atoms to discriminate the excitation signal in two energy level transition spectral lines, and locks the frequency of the excitation signal obtained by the signal obtaining device 41 on the center frequency of the transition spectral line through a frequency locking loop, thereby realizing second-defined recurrence.
Alternatively, the signal acquiring device 41 may be the signal acquiring device in the embodiment shown in fig. 1 and fig. 2.
Those of ordinary skill in the art will understand that: all or a portion of the steps of implementing the above-described method embodiments may be performed by hardware associated with program instructions. The aforementioned program may be stored in a computer-readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A signal acquisition apparatus, comprising: the device comprises a laser frequency shift unit, an ultra-stable microwave frequency conversion unit, a standard signal acquisition unit, a long-term stability acquisition unit and an excitation signal acquisition unit;
the laser frequency shift unit is used for generating an ultrastable microwave according to the ultrastable laser;
the input end of the ultra-stable microwave frequency conversion unit is connected with the output end of the laser frequency shift unit, and the ultra-stable microwave frequency conversion unit is used for generating high-frequency ultra-stable microwaves with the same stability as the ultra-stable microwaves according to the ultra-stable microwaves;
the input end of the standard signal obtaining unit is connected with the output end of the ultra-stable microwave frequency conversion unit, and the standard signal obtaining unit is used for generating a standard high-frequency signal according to the high-frequency ultra-stable microwave;
the input end of the long-term stability obtaining unit is connected with the output end of the standard signal obtaining unit, and the long-term stability obtaining unit is used for compensating the frequency drift of the ultrastable laser according to the standard high-frequency signal;
the input end of the excitation signal obtaining unit is respectively connected with the output end of the standard signal obtaining unit and the output end of the ultra-stable microwave frequency conversion unit, and the excitation signal obtaining unit is used for generating an excitation signal according to the standard high-frequency signal and the high-frequency ultra-stable microwave.
2. The apparatus of claim 1, wherein the laser frequency shift unit comprises: the device comprises an acousto-optic modulator, an optical frequency comb, a first direct digital frequency synthesizer and a first hydrogen clock;
the acousto-optic modulator is used for shifting the frequency of the ultrastable laser and locking the optical frequency comb on the frequency-shifted ultrastable laser to generate the ultrastable microwave;
the driving signal used by the radio frequency source of the acousto-optic modulator is provided by the first direct digital frequency synthesizer, and the first direct digital frequency synthesizer is controlled by the error signal output by the long-term stability obtaining unit and the first hydrogen clock.
3. The apparatus of claim 1, wherein the ultra-stable microwave frequency conversion unit comprises a first dielectric oscillator.
4. The apparatus of claim 1, wherein the standard signal obtaining unit comprises: the system comprises a constant temperature crystal oscillator, a first processing unit, a second medium oscillator, a beat frequency unit, a phase frequency and phase discrimination unit, a filter, a frequency synthesizer and a second hydrogen clock;
the input end of the second dielectric oscillator is connected with the output end of the constant-temperature crystal oscillator, and the second dielectric oscillator is used for generating a first microwave signal according to the standard high-frequency signal output by the constant-temperature crystal oscillator;
the beat frequency unit is used for carrying out beat frequency processing on the high-frequency ultrastable microwave and the first microwave signal to obtain a low-frequency signal, and the low-frequency signal is transmitted to the frequency and phase discrimination unit through the filter;
the input end of the phase frequency and phase detection unit is also connected with the frequency synthesizer, and the phase frequency and phase detection unit is used for performing phase frequency and phase detection processing on the signal output by the filter and the signal output by the frequency synthesizer to obtain a first error signal; said frequency synthesizer is served by said second hydrogen clock;
the input end of the first processing unit is connected with the output end of the phase frequency and phase discrimination unit, the first processing unit is used for filtering, proportionally amplifying and integrating the first error signal, and sending the processed first error signal to the constant-temperature crystal oscillator, so that the constant-temperature crystal oscillator generates the standard high-frequency signal according to the processed first error signal.
5. The apparatus of claim 4, wherein the frequency of the standard high frequency signal is 100 MHz.
6. The apparatus according to claim 1, wherein the long-term stability obtaining unit includes: the phase discrimination unit, the third hydrogen clock and the second processing unit;
the phase discrimination unit is used for performing phase discrimination processing on the standard high-frequency signal and a signal output by the third hydrogen clock to generate a second error signal;
the second processing unit is used for performing filtering, proportional amplification and integral processing on the second error signal to obtain a processed second error signal, and the second error signal is used for compensating the frequency drift of the ultrastable laser.
7. The apparatus of claim 1, wherein the excitation signal obtaining unit comprises: the first single-side mixer, the second single-side mixer, the frequency synthesis unit, the power attenuator, the power divider, the phase shifter, the interference switch, the fourth hydrogen clock and the second direct digital frequency synthesizer;
the power divider is used for amplifying and distributing power of the standard high-frequency signal; the output end of the power divider is respectively connected with the power attenuator and the phase shifter;
the power attenuator is used for performing power attenuation on the received signal and transmitting the attenuated signal to the frequency synthesis unit;
the phase shifter is used for performing phase shifting processing on the received signal and transmitting the phase-shifted signal to the frequency synthesis unit through the interference switch;
the input end of the first single-side mixer is respectively connected with the output end of the frequency synthesis unit and the output end of the ultra-stable microwave frequency obtaining unit, and the first single-side mixer is used for performing frequency mixing processing on the high-frequency ultra-stable microwave and the signal output by the frequency synthesis unit to obtain a first mixing signal;
the input end of the second single-side mixer is connected to the output end of the first single-side mixer and the output end of the second direct digital frequency synthesizer served by the fourth clock, respectively, and the second single-side mixer is configured to generate the excitation signal according to the first mixing signal and a signal output by the second direct digital frequency synthesizer.
8. The device of claim 7, wherein the first hydrogen clock, the second hydrogen clock, the third hydrogen clock, and the fourth hydrogen clock are the same hydrogen clock.
9. A signal acquisition method applied to the signal acquisition apparatus according to any one of claims 1 to 8, the method comprising:
generating an ultrastable microwave according to the ultrastable laser by the laser frequency shift unit;
generating high-frequency ultra-stable microwaves with the same stability as the ultra-stable microwaves according to the ultra-stable microwaves by the ultra-stable microwave frequency conversion unit;
generating a standard high-frequency signal according to the high-frequency ultra-stable microwave through the standard signal obtaining unit;
compensating the frequency drift of the ultrastable laser by the long-term stability obtaining unit according to the standard high-frequency signal;
and generating an excitation signal according to the standard high-frequency signal and the high-frequency ultra-stable microwave by the excitation signal obtaining unit.
10. An atomic fountain clock, wherein the atomic fountain clock discriminates an excitation signal by using transition lines of electrons in the interior of atoms at two energy levels, and locks the frequency of the excitation signal acquired by the signal acquisition device as claimed in any one of claims 1 to 8 to the center frequency of the transition lines via a frequency lock loop, thereby realizing a reproduction defined in seconds.
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5381147A (en) * | 1992-05-15 | 1995-01-10 | Deutsche Aerospace Ag | Process for the analog-to-digital conversion of microwave signals |
| CN1973248A (en) * | 2004-03-30 | 2007-05-30 | 国家科研中心 | Method for modulating an atomic clock signal with coherent population trapping and corresponding atomic clock |
| RU2408978C1 (en) * | 2009-07-13 | 2011-01-10 | Открытое акционерное общество "Российский институт радионавигации и времени" | Quantum frequency standard on gas cell with laser optical pumping |
| WO2011053634A1 (en) * | 2009-10-27 | 2011-05-05 | Qualcomm Incorporated | Low-power oscillator |
| CN102307088A (en) * | 2011-09-13 | 2012-01-04 | 清华大学 | Atomic time signal receiving system and method |
| CN103684611A (en) * | 2013-12-04 | 2014-03-26 | 上海交通大学 | Phase stabilized millimeter wave generating system and method |
| CN104821850A (en) * | 2015-04-09 | 2015-08-05 | 中国科学院半导体研究所 | Device for actively calibrating optical fiber transmission of microwave signals by means of photoelectric oscillator |
| CN105933065A (en) * | 2016-04-08 | 2016-09-07 | 上海交通大学 | Optical carrier suppression-based optical fiber distribution system and method of photo-produced microwave signals |
| CN106773612A (en) * | 2017-01-12 | 2017-05-31 | 中国科学院上海光学精密机械研究所 | Improve the system and method for atomic frequency stability |
| CN107783412A (en) * | 2017-11-03 | 2018-03-09 | 中国科学院国家授时中心 | Two photon transition rubidium atomic clock |
-
2018
- 2018-08-09 CN CN201810905020.1A patent/CN110824888B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5381147A (en) * | 1992-05-15 | 1995-01-10 | Deutsche Aerospace Ag | Process for the analog-to-digital conversion of microwave signals |
| CN1973248A (en) * | 2004-03-30 | 2007-05-30 | 国家科研中心 | Method for modulating an atomic clock signal with coherent population trapping and corresponding atomic clock |
| RU2408978C1 (en) * | 2009-07-13 | 2011-01-10 | Открытое акционерное общество "Российский институт радионавигации и времени" | Quantum frequency standard on gas cell with laser optical pumping |
| WO2011053634A1 (en) * | 2009-10-27 | 2011-05-05 | Qualcomm Incorporated | Low-power oscillator |
| CN102307088A (en) * | 2011-09-13 | 2012-01-04 | 清华大学 | Atomic time signal receiving system and method |
| CN103684611A (en) * | 2013-12-04 | 2014-03-26 | 上海交通大学 | Phase stabilized millimeter wave generating system and method |
| CN104821850A (en) * | 2015-04-09 | 2015-08-05 | 中国科学院半导体研究所 | Device for actively calibrating optical fiber transmission of microwave signals by means of photoelectric oscillator |
| CN105933065A (en) * | 2016-04-08 | 2016-09-07 | 上海交通大学 | Optical carrier suppression-based optical fiber distribution system and method of photo-produced microwave signals |
| CN106773612A (en) * | 2017-01-12 | 2017-05-31 | 中国科学院上海光学精密机械研究所 | Improve the system and method for atomic frequency stability |
| CN107783412A (en) * | 2017-11-03 | 2018-03-09 | 中国科学院国家授时中心 | Two photon transition rubidium atomic clock |
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