CN103297047B - Atomic frequency standard and servo lock method - Google Patents
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Abstract
The invention discloses a kind of atomic frequency standard and servo lock method, belong to Technology of Atomic Frequency Standards field, described atomic frequency standard comprises: VCXO; Integration module, for generation of comprehensive modulation signal; Fixed ampllitude module, for the amplitude of comprehensive modulation signal is transformed into predetermined value, obtains the comprehensive modulation signal of fixed ampllitude; Radio frequency times frequency module, for carrying out frequency multiplication to the output signal of VCXO, obtains frequency-doubled signal; Microwave times frequency mixing module, for by comprehensive for fixed ampllitude modulation signal and frequency-doubled signal times mixing, produces microwave and seeks signal; Physical location, carries out quantum frequency discrimination for seeking signal to microwave, produces quantum frequency discrimination signal; Servo module, for carrying out synchronous phase demodulation to quantum frequency discrimination signal, producing correction voltage and acting on VCXO.The present invention, by the amplitude of comprehensive modulation signal is transformed into predetermined value, obtains the comprehensive modulation signal of amplitude stability, improves the output frequency precision of atomic frequency standard complete machine.
Description
Technical field
The present invention relates to Technology of Atomic Frequency Standards field, particularly a kind of atomic frequency standard and servo lock method.
Background technology
For obtaining temporal frequency more stable in the Nature, people are by applying low-intensity magnetic field to atoms such as rubidium, caesium, hydrogen, make its atomic energy level change excitation state into by ground state, utilize the ground state hyperfine structure 0-0 transition center frequency do not disturbed by external magnetic field as reference time frequency values.
The atomic frequency standard utilizing above-mentioned principle to make mainly comprises with lower part: VCXO, isolated amplifier, radio frequency times frequency module, microwave times frequency mixing module, physical location, servo module and integration module; The output signal of isolated amplifier to VCXO is isolated and amplifies, the output signal of isolated amplifier exports microwave times frequency mixing module to through a radio frequency times frequency module, integration module is for generation of a comprehensive modulation signal in road, output signal and the comprehensive modulation signal of microwave times frequency mixing module radio frequency times frequency module carry out SHG and THG, to produce microwave interrogation signals; Physical location carries out frequency discrimination to microwave interrogation signals, produces quantum frequency discrimination signal; Servo module carries out carrying out synchronous phase demodulation with reference signal after frequency-selecting is amplified to quantum frequency discrimination signal, produces correction voltage and acts on VCXO, to adjust the output frequency of VCXO; By said structure unit, the output frequency of VCXO is locked in atomic ground state hyperfine 0-0 transition center frequency the most at last.Wherein, have employed variable capacitance diode modulation circuit in above-mentioned integration module.
Realizing in process of the present invention, inventor finds that prior art at least exists following problem:
Because variable capacitance diode modulation circuit is temperature sensing element, when variation of ambient temperature, the amplitude of the comprehensive modulation signal of output inevitably will be caused to change, cause amplitude unstable, and the microwave that the comprehensive modulation signal of amplitude shakiness produces seeks signal, in physical location, frequency discrimination will cause correction voltage inaccurate, and then draws the output frequency of inclined atomic frequency standard complete machine.
Summary of the invention
Unstable in order to solve comprehensive modulation signal amplitude in prior art, and then draw the problem of output frequency of inclined atomic frequency standard complete machine, embodiments provide a kind of atomic frequency standard and servo lock method.Described technical scheme is as follows:
On the one hand, embodiments provide a kind of atomic frequency standard, described atomic frequency standard comprises:
VCXO;
Integration module, for generation of comprehensive modulation signal;
Fixed ampllitude module, the amplitude for the described comprehensive modulation signal produced by described integration module is transformed into predetermined value, obtains the comprehensive modulation signal of fixed ampllitude;
Radio frequency times frequency module, for carrying out frequency multiplication to the output signal of described VCXO, obtains frequency-doubled signal;
Microwave times frequency mixing module, for the described frequency-doubled signal times mixing comprehensive modulation signal of described fixed ampllitude of described fixed ampllitude module generation and described radio frequency times frequency module produced, produces microwave and seeks signal;
Physical location, the described microwave for producing described microwave times frequency mixing module is sought signal and is carried out quantum frequency discrimination, produces quantum frequency discrimination signal;
Servo module, carries out synchronous phase demodulation for the described quantum frequency discrimination signal produced described physical location, produces correction voltage and acts on described VCXO;
Described VCXO is electrically connected with described radio frequency times frequency module, described integration module and described servo module respectively, described microwave times frequency mixing module is electrically connected with described radio frequency times frequency module, described fixed ampllitude module and described physical location respectively, described servo module is electrically connected with described physical location and described integration module respectively, and described fixed ampllitude module is electrically connected with described integration module;
Described servo module comprises:
Choosing puts unit, for carrying out frequency-selecting amplification to described quantum frequency discrimination signal;
Second processing unit, for carrying out synchronous phase demodulation to the described quantum frequency discrimination signal after frequency-selecting amplification and reference signal, produces voltage difference, according to described voltage difference and frequency stability range computation programme-controlled gain value;
Programme-controlled gain unit, for adopting described programme-controlled gain value to carry out programming amplifying to the described voltage difference that described second processing unit produces, obtains described correction voltage;
Digital to analog converter, for acting on described VCXO by described correction voltage;
Described second processing unit programme-controlled gain value according to following formulae discovery:
A≤(2+b)V1/[(2-b)U]，
Wherein, A is programme-controlled gain value, and b is frequency stability, and described frequency stability scope is for being less than or equal to b, and V1 is the last correction voltage exported, and U is described voltage difference.
In a kind of implementation of the embodiment of the present invention, described fixed ampllitude module comprises:
First processing unit, for the magnitude of voltage of described comprehensive modulation signal of sampling, and calculate actual magnitude according to the magnitude of voltage sampled, calculate multiplication factor according to predetermined value and described actual magnitude, described actual magnitude refers to the difference of the magnitude of voltage of sampling in one-period between peak value and valley;
Compensating unit, for the described multiplication factor adopting described first processing unit to calculate, amplifies the voltage of described comprehensive modulation signal, obtains the comprehensive modulation signal of described fixed ampllitude;
Described compensating unit is electrically connected with described integration module, described first processing unit and a described microwave times frequency mixing module respectively, and described first processing unit is electrically connected with described integration module.
In the another kind of implementation of the embodiment of the present invention, described compensating unit comprises: the first operational amplifier, first resistance, second resistance and digital potentiometer, the inverting input of described first operational amplifier is by described first grounding through resistance, the in-phase input end of described first operational amplifier is electrically connected with the output of described integration module by described second resistance, between the inverting input that described digital potentiometer is connected to described first operational amplifier and output, the output of described first operational amplifier is electrically connected with a described microwave times frequency mixing module, described digital potentiometer is electrically connected with described first processing unit.
In the another kind of implementation of the embodiment of the present invention, described integration module comprises: Direct Digital Synthesizer, the master clock pin of described Direct Digital Synthesizer connects described VCXO, and the control bit pin of described Direct Digital Synthesizer connects described servo module.
On the other hand, the embodiment of the present invention additionally provides a kind of servo lock method of atomic frequency standard, and described method comprises:
The integration module of atomic frequency standard is adopted to produce comprehensive modulation signal;
The amplitude of described comprehensive modulation signal is transformed into predetermined value, obtains the comprehensive modulation signal of fixed ampllitude;
Frequency multiplication is carried out to the output signal of VCXO, obtains frequency-doubled signal;
By comprehensive for described fixed ampllitude modulation signal and times mixing of described frequency-doubled signal, produce microwave and seek signal;
Signal is sought to described microwave and carries out quantum frequency discrimination, produce quantum frequency discrimination signal;
Synchronous phase demodulation is carried out to described quantum frequency discrimination signal, produces correction voltage and act on described VCXO;
The described amplitude by comprehensive modulation signal is transformed into predetermined value, obtains the comprehensive modulation signal of fixed ampllitude and comprises:
To sample the magnitude of voltage of described comprehensive modulation signal, and calculate actual magnitude according to the magnitude of voltage sampled, calculate multiplication factor according to described predetermined value and described actual magnitude, described actual magnitude refers to the difference of the magnitude of voltage of sampling in one-period between peak value and valley;
Adopt the voltage of described multiplication factor to described comprehensive modulation signal to amplify, obtain the comprehensive modulation signal of described fixed ampllitude.
In a kind of implementation of the embodiment of the present invention, described synchronous phase demodulation is carried out to quantum frequency discrimination signal, produces correction voltage and act on VCXO, comprising:
Synchronous phase demodulation is carried out to described quantum frequency discrimination signal, produces voltage difference;
According to described voltage difference and frequency stability range computation programme-controlled gain value;
Adopt described programme-controlled gain value to carry out programming amplifying to described voltage difference, obtain described correction voltage and export described VCXO to.
In the another kind of implementation of the embodiment of the present invention, programme-controlled gain value according to following formulae discovery:
A≤(2+b)V1/[(2-b)U]，
Wherein, A is programme-controlled gain value, and b is frequency stability, and described frequency stability scope is for being less than or equal to b, and V1 is the last correction voltage exported, and U is described voltage difference.
The beneficial effect that the technical scheme that the embodiment of the present invention provides is brought is:
By the amplitude of comprehensive modulation signal is transformed into predetermined value, obtain the comprehensive modulation signal of amplitude stability, avoid the output frequency of atomic frequency standard complete machine that the puppet correction voltage that brings because of amplitude shakiness causes and drawn inclined problem, improve the output frequency precision of atomic frequency standard complete machine.
Accompanying drawing explanation
In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the structural representation of the atomic frequency standard that the embodiment of the present invention one provides;
Fig. 2 is the flow chart of the servo lock method of the atomic frequency standard that the embodiment of the present invention two provides.
Embodiment
For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail.
Embodiment one
Embodiments provide a kind of atomic frequency standard, see Fig. 1, this atomic frequency standard comprises:
VCXO 101;
Integration module 104, for generation of comprehensive modulation signal;
Fixed ampllitude module 105, the amplitude for the comprehensive modulation signal produced by integration module 104 is transformed into predetermined value, obtains the comprehensive modulation signal of fixed ampllitude;
Radio frequency times frequency module 103, for carrying out frequency multiplication to the output signal of VCXO 101, obtains frequency-doubled signal;
Microwave times frequency mixing module 106, the frequency-doubled signal times mixing that the comprehensive modulation signal of the fixed ampllitude for fixed ampllitude module 105 being produced and radio frequency times frequency module 103 produce, produces microwave and seeks signal;
Physical location 107, the microwave for producing microwave times frequency mixing module 106 is sought signal and is carried out quantum frequency discrimination, produces quantum frequency discrimination signal;
Servo module 108, carries out synchronous phase demodulation for the quantum frequency discrimination signal produced physical location 107, produces correction voltage and acts on VCXO 101.
Preferably, fixed ampllitude module 105 comprises:
First processing unit, for the magnitude of voltage of comprehensive modulation signal of sampling, and calculate actual magnitude according to the magnitude of voltage sampled, calculate multiplication factor according to predetermined value and actual magnitude, actual magnitude refers to the difference of the magnitude of voltage of sampling in one-period between peak value and valley;
Compensating unit, the voltage of multiplication factor to comprehensive modulation signal calculated for adopting the first processing unit amplifies, and obtains the comprehensive modulation signal of fixed ampllitude;
Wherein, compensating unit is electrically connected with integration module 104, first processing unit and microwave times frequency mixing module 106 respectively, and the first processing unit is electrically connected with integration module 104.This first processing unit comprises processor and the first analog to digital converter.
What deserves to be explained is, predetermined value can be arranged according to following method: sampling comprehensive modulation signal medium frequency is that the amplitude of F0 and F1 is respectively Va and Vb, and so predetermined value is (Va+Vb)/N, and N is here greater than 1, as N=5.
Further, compensating unit comprises: the first operational amplifier, the first resistance, the second resistance and digital potentiometer, the inverting input of the first operational amplifier is by the first grounding through resistance, the in-phase input end of the first operational amplifier is electrically connected with the output of integration module by the second resistance, between the inverting input that digital potentiometer is connected to the first operational amplifier and output, the output of the first operational amplifier is electrically connected with a microwave times frequency mixing module, and digital potentiometer is electrically connected with the first processing unit.First processing unit realizes the amplification of the above-mentioned multiplication factor calculated by control figure potentiometer.
Preferably, integration module 104 comprises DDS (DirectDigitalSynthesizer, Direct Digital Synthesizer).DDS can adopt AD9832 chip and peripheral circuit composition.The control bit pin that the master clock pin of DDS connects VCXO 101, DDS connects servo module 108.In another kind of implementation, integration module 104 can adopt di-cap circuit realiration.
Particularly, MCLK (master clock) pin of AD9832 chip connects external clock reference (as VCXO), and the stability of the frequency signal that OUT (output) pin exports is consistent with external clock reference.FSELECT (control bit) pin is keying FM signal input, namely 79Hz keying FM signal (being produced by servo module 108) input, there are two frequency control register AD9832 inside, by the frequency value F 0 that the mode of programming will pre-set, F1 preserves in a register, when FSELECT pin has square-wave signal to input (level rising edge or trailing edge conversion), the IOUT pin of AD9832 will read the value of F1 or F0 as output thereupon respectively from frequency control register, and the phase place of meeting inhibit signal is unchanged, as IOUT pin can export F1 when the high level of modulated square wave 79Hz signal, at low level output F0.DDS also comprises PSEL0 (phase control position), the PSEL1 of the phase place regulating two paths of signals frequency F1, F0, and in order to keep F1, F0 Phase Continuation when switching, therefore directly by PSEL0, PSEL1 ground connection.
Before DDS input, the DATA (data) of the value representing F1 and F0 is write in 2 frequency control register (for storing the frequency values of F0, F1) of AD9832 inside at twice, and only after DATA write, DDS could export.
For the minimum frequency resolution that the clock frequency of 32 bit frequency control registers, the input of MCLK pin is 20MHz, AD9832 be:
Therefore, in DATA, the value of F0 is (F0/20MHz) * 2
32, obtained decimal value is converted into binary system, obtains the value of the corresponding 32 bit frequency control registers of F0; In DATA, the value of F1 is (F1/20MHz) * 2
32, obtained decimal value is converted into binary system, obtains the value of the corresponding 32 bit frequency control registers of F1.
In concrete practical application, to the signal that DDS exports, need after filtering, shaping, to be just incorporated in other circuit link after the process such as amplification.For obtaining purer signal spectra, after IOUT pin exports, usually connect a band pass filter or low pass filter.
Preferably, servo module 108 comprises:
Choosing puts unit 1081, for carrying out frequency-selecting amplification to quantum frequency discrimination signal;
Second processing unit 1082, for carrying out synchronous phase demodulation to the quantum frequency discrimination signal after frequency-selecting amplification and reference signal, produce voltage difference, according to voltage difference and frequency stability range computation programme-controlled gain value, frequency stability scope is arranged according to the actual requirements;
Programme-controlled gain unit 1083, for adopting programme-controlled gain value to carry out programming amplifying to the voltage difference that the second processing unit 1082 produces, obtains voltage of rectifying a deviation;
Digital to analog converter 1084, for acting on VCXO by correction voltage.
Wherein, the second processing unit 1082 can comprise the second analog to digital converter and processor.
Particularly, in order to realize synchronous phase demodulation, in servo module 108, the second processing unit 1082 needs to produce the clearly adjustable keying FM signal of phase relation each other and reference signal, and the frequency of keying FM signal and reference signal is preferably 79Hz.The generation of these signals is realized by corresponding tick interrupt or hardware divider technology by processor.The square-wave signal of keying FM signal and reference signal can be duty ratio be 1:1, keying FM signal is given the DDS in integration module 104 thus is produced comprehensive modulation signal, and namely processor is connected with the FSELECT pin of DDS.
What deserves to be explained is, the processor in the second processing unit 1082 can adopt a processor to realize with the processor in the first processing unit.
Preferably, programme-controlled gain unit 1083 can comprise the second operational amplifier.
What deserves to be explained is, quantum frequency discrimination signal from physical location 107 obtains a similar square wave after frequency-selecting is amplified, processor is according to the above-mentioned quantum frequency discrimination signal after treatment of ordered pair during synchronized sampling, and synchronous reference signal is sampled, obtain corresponding magnitude of voltage U1, U2 respectively, obtain voltage difference U=U2-U1.
Programme-controlled gain unit calculates correction voltage V according to voltage difference U and programme-controlled gain value A, that is:
V=A*U formula 1.
Wherein, the size of A is determined by frequency stability scope, even if after the correction voltage that A*U produces is applied to VCXO, VCXO output signal frequency changes within the scope of atomic frequency standard stability requirement.
Wherein, in atomic frequency standard, the voltage-controlled slope k of VCXO defines the relation between correction voltage V and output frequency f:
F=kV formula 2.
If double correction voltage (V1, V2) act on VCXO and obtain output signal frequency (f1, f2), 2. can obtain according to formula: f1=kV1, f2=kV2, the frequency change a that the effect of twice correction voltage makes VCXO export is:
A=(f2-f1)/[(f2+f1)/2] formula 3.
Due to, the frequency change a that twice effect makes VCXO export will meet frequency stability scope: be less than or equal to frequency stability b, that is:
A≤b formula 4.
Wherein, b is atomic frequency standard frequency stability.
3. formula is substituted into and 4. can obtain,
(f2-f1)/[(f2+f1)/2]≤b formula 5.
Wherein, f1=kV1, f2=kV2,
So 5. above-mentioned formula can be converted into:
(kV2–kV1)/[(kV2+kV1)/2]≤b，
k(V2–V1)/[k(V2+V1)/2]≤b，
(V2–V1)/[(V2+V1)/2]≤b，
V2–V1≤b(V2+V1)/2，
V2–V1≤(bV2)/2+(bV1)/2，
(1-b/2)V2≤(1+b/2)V1，
V2≤(1+b/2) V1/ (1-b/2) formula 6.
V2 is the current correction voltage calculated according to voltage difference U and programme-controlled gain value A, therefore 1. formula can be written as: V2=A*U, and substitutes into formula and 6. can obtain,
AU≤(2+b)V1/(2-b)，
A≤(2+b)V1/[(2-b)U]。
To sum up, A≤(2+b) V1/ [(2-b) U], wherein, U is that current voltage is poor, and V1 is the correction voltage exported last time.
Therefore, programme-controlled gain unit 1083 can calculate the value of A according to A≤(2+b) V1/ [(2-b) U].
In one implementation, require that to meet frequency stability be 5E-12 when locking, and meets frequency stability 5E-10 when non-locking, thus the scope of A when can calculate locking and time non-locking, the value of A according to locking and non-lockingly can be selected.Locking for atomic frequency standard is judged as existing mature technology, repeats no more here.
In a further mode of operation, the frequency stability only met as required is 5E-12, calculates the scope of A, gets the value of maximum wherein as A.
Below the effect of programme-controlled gain unit is briefly described: when microwave interrogation signals is away from (non-locking during atomic ground state hyperfine 0-0 transition center frequency in physical location, no matter be less than normal or bigger than normal), theoretically, we wish that VCXO significantly changes, thus make microwave interrogation signals faster close to the atomic ground state hyperfine 0-0 transition center frequency in physical location.Now the absolute difference of U=U2-U1 will be very large, and the correction voltage A*U that programme-controlled gain unit obtains is also very large, be applied to after VCXO make its output signal frequency occur significantly to change through digital-to-analogue conversion output voltage.When microwave interrogation signals is close to (locking during atomic ground state hyperfine 0-0 transition center frequency in physical location, no matter be less than normal or bigger than normal), if at this moment make VCXO produce with significantly gain correction more significantly to change, locking atomic ground state hyperfine 0-0 transition center frequency will be unfavorable for, now we wish that VCXO slightly changes correction, thus make microwave interrogation signals more accurate close to the atomic ground state hyperfine 0-0 transition center frequency in physical location.Because now the absolute value of U is very little, the correction voltage A*U that programme-controlled gain unit obtains is also very little, makes its output signal frequency that slightly change occur so be applied to after VCXO through digital-to-analogue conversion output voltage.
Alternatively, this atomic frequency standard also comprises: isolated amplifier 102, and this isolated amplifier 102 is connected between VCXO 101 and radio frequency times frequency module 103.
The embodiment of the present invention is by being transformed into predetermined value by the amplitude of comprehensive modulation signal, obtain the comprehensive modulation signal of amplitude stability, avoid the output frequency of atomic frequency standard complete machine that the puppet correction voltage that brings because of amplitude shakiness causes and drawn inclined problem, improve the output frequency precision of atomic frequency standard complete machine.
Embodiment two
Embodiments provide a kind of servo lock method of atomic frequency standard, see Fig. 2, the method comprises:
Step 201: produce comprehensive modulation signal.
Step 202: the amplitude of comprehensive modulation signal is transformed into predetermined value by fixed ampllitude module, obtains the comprehensive modulation signal of fixed ampllitude.
Preferably, step 202 can comprise:
The magnitude of voltage of step one, comprehensive modulation signal of sampling, and calculate actual magnitude according to the magnitude of voltage sampled, calculate multiplication factor according to predetermined value and actual magnitude, actual magnitude refers to the difference of the magnitude of voltage of sampling in one-period between peak value and valley.
What deserves to be explained is, here predetermined value can be arranged according to following method: supposing to sample comprehensive modulation signal medium frequency is that the amplitude of F0 and F1 is respectively Va and Vb, so predetermined value can be V=(Va+Vb)/N, and N is here greater than 1, as N=5.
Step 2, the voltage of employing multiplication factor to comprehensive modulation signal amplify, and obtain the comprehensive modulation signal of fixed ampllitude.
Step 203: radio frequency times frequency module carries out frequency multiplication to the output signal of VCXO, obtains frequency-doubled signal.
There is no sequencing between step 203 and above-mentioned steps 201,202, can perform simultaneously.
Step 204: microwave times frequency mixing module, by comprehensive for fixed ampllitude modulation signal and frequency-doubled signal times mixing, produces microwave and seeks signal.
Step 205: physical location is sought signal to microwave and carried out quantum frequency discrimination, produces quantum frequency discrimination signal.
Step 206: servo module carries out synchronous phase demodulation to quantum frequency discrimination signal, produces correction voltage and acts on VCXO.
Preferably, step 206 can comprise:
Step one, synchronous phase demodulation is carried out to quantum frequency discrimination signal, produce voltage difference;
Step 2, according to voltage difference and frequency stability range computation programme-controlled gain value;
Step 3, employing programme-controlled gain value carry out programming amplifying to voltage difference, obtain correction voltage and export VCXO to.
Particularly, can according to following formulae discovery programme-controlled gain value in step 2:
A≤(2+b) V1/ [(2-b) U], A is programme-controlled gain value, and b is frequency stability, and frequency stability scope is for being less than or equal to b, and V1 is the last correction voltage exported, and U is voltage difference.
The embodiment of the present invention is by being transformed into predetermined value by the amplitude of comprehensive modulation signal, obtain the comprehensive modulation signal of amplitude stability, avoid the output frequency of atomic frequency standard complete machine that the puppet correction voltage that brings because of amplitude shakiness causes and drawn inclined problem, improve the output frequency precision of atomic frequency standard complete machine.
The invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.
It should be noted that: the atomic frequency standard that above-described embodiment provides is when carrying out work, only be illustrated with the division of above-mentioned each functional module, in practical application, can distribute as required and by above-mentioned functions and be completed by different functional modules, internal structure by atomic frequency standard is divided into different functional modules, to complete all or part of function described above.In addition, the atomic frequency standard that above-described embodiment provides and atomic frequency standard servo lock embodiment of the method belong to same design, and its specific implementation process refers to embodiment of the method, repeats no more here.
One of ordinary skill in the art will appreciate that all or part of step realizing above-described embodiment can have been come by hardware, the hardware that also can carry out instruction relevant by program completes, described program can be stored in a kind of computer-readable recording medium, the above-mentioned storage medium mentioned can be read-only memory, disk or CD etc.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (7)
1. an atomic frequency standard, is characterized in that, described atomic frequency standard comprises:
VCXO;
Integration module, for generation of comprehensive modulation signal;
Fixed ampllitude module, the amplitude for the described comprehensive modulation signal produced by described integration module is transformed into predetermined value, obtains the comprehensive modulation signal of fixed ampllitude;
Radio frequency times frequency module, for carrying out frequency multiplication to the output signal of described VCXO, obtains frequency-doubled signal;
Microwave times frequency mixing module, for the described frequency-doubled signal times mixing comprehensive modulation signal of described fixed ampllitude of described fixed ampllitude module generation and described radio frequency times frequency module produced, produces microwave and seeks signal;
Physical location, the described microwave for producing described microwave times frequency mixing module is sought signal and is carried out quantum frequency discrimination, produces quantum frequency discrimination signal;
Servo module, carries out synchronous phase demodulation for the described quantum frequency discrimination signal produced described physical location, produces correction voltage and acts on described VCXO;
Described VCXO is electrically connected with described radio frequency times frequency module, described integration module and described servo module respectively, described microwave times frequency mixing module is electrically connected with described radio frequency times frequency module, described fixed ampllitude module and described physical location respectively, described servo module is electrically connected with described physical location and described integration module respectively, and described fixed ampllitude module is electrically connected with described integration module;
Described servo module comprises:
Choosing puts unit, for carrying out frequency-selecting amplification to described quantum frequency discrimination signal;
Second processing unit, for carrying out synchronous phase demodulation to the described quantum frequency discrimination signal after frequency-selecting amplification and reference signal, produces voltage difference, according to described voltage difference and frequency stability range computation programme-controlled gain value;
Programme-controlled gain unit, for adopting described programme-controlled gain value to carry out programming amplifying to the described voltage difference that described second processing unit produces, obtains described correction voltage;
Digital to analog converter, for acting on described VCXO by described correction voltage;
Described second processing unit programme-controlled gain value according to following formulae discovery:
A≤(2+b)V1/[(2-b)U]，
Wherein, A is programme-controlled gain value, and b is frequency stability, and described frequency stability scope is for being less than or equal to b, and V1 is the last correction voltage exported, and U is described voltage difference.
2. atomic frequency standard as claimed in claim 1, it is characterized in that, described fixed ampllitude module comprises:
First processing unit, for the magnitude of voltage of described comprehensive modulation signal of sampling, and calculate actual magnitude according to the magnitude of voltage sampled, calculate multiplication factor according to predetermined value and described actual magnitude, described actual magnitude refers to the difference of the magnitude of voltage of sampling in one-period between peak value and valley;
Compensating unit, for the described multiplication factor adopting described first processing unit to calculate, amplifies the voltage of described comprehensive modulation signal, obtains the comprehensive modulation signal of described fixed ampllitude;
Described compensating unit is electrically connected with described integration module, described first processing unit and a described microwave times frequency mixing module respectively, and described first processing unit is electrically connected with described integration module.
3. atomic frequency standard as claimed in claim 2, it is characterized in that, described compensating unit comprises: the first operational amplifier, first resistance, second resistance and digital potentiometer, the inverting input of described first operational amplifier is by described first grounding through resistance, the in-phase input end of described first operational amplifier is electrically connected with the output of described integration module by described second resistance, between the inverting input that described digital potentiometer is connected to described first operational amplifier and output, the output of described first operational amplifier is electrically connected with a described microwave times frequency mixing module, described digital potentiometer is electrically connected with described first processing unit.
4. atomic frequency standard as claimed in claim 1, it is characterized in that, described integration module comprises: Direct Digital Synthesizer, the master clock pin of described Direct Digital Synthesizer connects described VCXO, and the control bit pin of described Direct Digital Synthesizer connects described servo module.
5. a servo lock method for atomic frequency standard, is characterized in that, described method comprises:
The integration module of atomic frequency standard is adopted to produce comprehensive modulation signal;
The amplitude of described comprehensive modulation signal is transformed into predetermined value, obtains the comprehensive modulation signal of fixed ampllitude;
Frequency multiplication is carried out to the output signal of VCXO, obtains frequency-doubled signal;
By comprehensive for described fixed ampllitude modulation signal and times mixing of described frequency-doubled signal, produce microwave and seek signal;
Signal is sought to described microwave and carries out quantum frequency discrimination, produce quantum frequency discrimination signal;
Synchronous phase demodulation is carried out to described quantum frequency discrimination signal, produces correction voltage and act on described VCXO; The described amplitude by comprehensive modulation signal is transformed into predetermined value, obtains the comprehensive modulation signal of fixed ampllitude and comprises:
To sample the magnitude of voltage of described comprehensive modulation signal, and calculate actual magnitude according to the magnitude of voltage sampled, calculate multiplication factor according to described predetermined value and described actual magnitude, described actual magnitude refers to the difference of the magnitude of voltage of sampling in one-period between peak value and valley;
Adopt the voltage of described multiplication factor to described comprehensive modulation signal to amplify, obtain the comprehensive modulation signal of described fixed ampllitude.
6. method as claimed in claim 5, is characterized in that, describedly carries out synchronous phase demodulation to quantum frequency discrimination signal, produces correction voltage and acts on VCXO, comprising:
Synchronous phase demodulation is carried out to described quantum frequency discrimination signal, produces voltage difference;
According to described voltage difference and frequency stability range computation programme-controlled gain value;
Adopt described programme-controlled gain value to carry out programming amplifying to described voltage difference, obtain described correction voltage and export described VCXO to.
7. method as claimed in claim 6, is characterized in that, programme-controlled gain value according to following formulae discovery:
A≤(2+b)V1/[(2-b)U]，
Wherein, A is programme-controlled gain value, and b is frequency stability, and described frequency stability scope is for being less than or equal to b, and V1 is the last correction voltage exported, and U is described voltage difference.
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| CN104410415A (en) * | 2014-11-27 | 2015-03-11 | 江汉大学 | Improved passive atomic frequency scale |
| CN105490163B (en) * | 2015-11-19 | 2018-11-20 | 江汉大学 | A kind of high frequency locking precision laser |
| CN105490156B (en) * | 2015-11-19 | 2019-06-21 | 江汉大学 | A kind of laser |
| CN105470803A (en) * | 2015-12-22 | 2016-04-06 | 江汉大学 | Laser frequency stabilizing apparatus |
| CN105811973B (en) * | 2016-03-17 | 2018-10-16 | 江汉大学 | A kind of inactive type rubidium atom frequency scale |
| CN106788426B (en) * | 2016-11-28 | 2019-10-15 | 中国科学院武汉物理与数学研究所 | A kind of CPT atomic frequency standard laser frequency modulation index locking device and method |
| CN107248696B (en) * | 2017-06-15 | 2021-08-03 | 江汉大学 | Self-compensating semiconductor laser |
| CN107979368B (en) * | 2017-12-20 | 2021-08-31 | 江汉大学 | Temperature control system of atomic frequency standard |
| CN107846220B (en) * | 2017-12-20 | 2021-10-22 | 江汉大学 | Atomic frequency standard |
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