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GB/T 39724-2020: Technical specifications and testing methods for cesium atomic clock
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Technical specifications and testing methods for cesium atomic clock
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Basic data | Standard ID | GB/T 39724-2020 (GB/T39724-2020) | | Description (Translated English) | Technical specifications and testing methods for cesium atomic clock | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | A57 | | Classification of International Standard | 17.080 | | Word Count Estimation | 25,216 | | Date of Issue | 2020-12-14 | | Date of Implementation | 2021-07-01 | | Regulation (derived from) | National Standard Announcement No. 28 of 2020 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | GB/T 39724-2020: Technical specifications and testing methods for cesium atomic clock---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Technical specifications and testing methods for cesium atomic clock
ICS 17.080
CCSA57
National Standards of People's Republic of China
Technical requirements and test methods for cesium atomic clock
2020-12-14 release
2021-07-01 implementation
State Administration for Market Regulation
Issued by the National Standardization Management Committee
Table of contents
Preface Ⅲ
1 Scope 1
2 Normative references 1
3 Terms and definitions 1
4 Classification and composition of cesium atomic clock 2
4.1 Overview 3
4.2 Classification of cesium atomic clock products 3
4.3 Composition of cesium atomic clock products 3
5 Technical requirements 3
5.1 Functional requirements 3
5.2 Performance requirements 4
5.3 Electrical characteristics 5
5.4 Communication function requirements 5
5.5 Power requirements 6
5.6 Appearance requirements 6
5.7 Dimensions and quality requirements 6
5.8 Power requirements 7
5.9 Environmental adaptability 7
5.10 Electromagnetic compatibility 7
5.11 Reliability and maintainability requirements 7
6 Test method 7
6.1 Test environment conditions 7
6.2 Test equipment 7
6.3 Test method 9
7 Inspection rules 18
7.1 Description of inspection rules 18
7.2 Identification and inspection 18
7.3 Factory inspection 18
7.4 Inspection items 18
Reference 21
Foreword
This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1.Structure and Drafting Rules of Standardization Documents"
Drafting.
Please note that certain contents of this document may involve patents. The issuing agency of this document is not responsible for identifying patents.
This document was proposed by the Equipment Development Department of the Central Military Commission.
This document is under the jurisdiction of the National Beidou Satellite Navigation Standardization Technical Committee (SAC/TC544).
Drafting organizations of this document. Peking University, China Institute of Metrology, China Satellite Navigation Engineering Center, China Aerospace Science and Technology Corporation
510 Institutes, Chengdu Tianao Electronics Co., Ltd., and 203 Institutes of the Second Research Institute of China Aerospace Science and Industry Corporation.
The main drafters of this document. Wang Yanhui, Zhang Aimin, Jiao Wenhai, Liu Ying, Wang Ji, Zhao Xingwen, Huang Kai.
Technical requirements and test methods for cesium atomic clock
1 Scope
This document specifies the technical requirements, test methods and inspection rules for cesium atomic clocks (also known as cesium atomic frequency standards) products.
This document is applicable to the development, production and acceptance of cesium atomic clock products.
2 Normative references
The contents of the following documents constitute indispensable clauses of this document through normative references in the text. Among them, dated quotations
Only the version corresponding to the date is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to
This document.
GB/T 1002-2008 Single-phase plug and socket type, basic parameters and dimensions for household and similar purposes
GB 4824-2019 Industrial, scientific and medical equipment radio frequency disturbance characteristic limits and measurement methods
GB/T 4857.23-2012 Packaging and Transportation Package Basic Test Part 23.Random Vibration Test Method
GB/T 6587-2012 General Specification for Electronic Measuring Instruments
GB/T 17626.3-2016 Electromagnetic compatibility test and measurement technology Radio frequency electromagnetic field radiation immunity test
GB/T 17626.4-2018 Electromagnetic compatibility test and measurement technology Electrical fast transient pulse group immunity test
GB/T 17626.6-2017 Electromagnetic compatibility test and measurement technology Radio frequency field induced conducted disturbance immunity
GB/T 17626.12-2013 Electromagnetic compatibility test and measurement technology Ring wave immunity test
GB/T 34094-2017 Information technology equipment power consumption measurement method
JJG492-2009 Cesium Atomic Frequency Standard Verification Regulation
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Magnetic sensitivity
The degree to which the output characteristics of the device change with the magnetic field within the normal working magnetic field environment.
Note. It is usually expressed by the amount of change in the device signal output characteristics (relative frequency deviation) caused by a unit Gauss change (1Gs per change).
3.2
Frequency repeatability
After the frequency standard has been working for a period of time and turned off, the frequency value will be consistent with the frequency value when it was turned off last time after it is turned on again to stabilize.
Note. Expressed by two relative frequency differences.
[Source. JJF1180-2007, 3.38, with modification]
3.3
Frequency adjustment range frequency setting range
The frequency output range that can be achieved by frequency adjustment commands.
3.4
Frequency adjustment resolution frequency setting resolution
The minimum value of frequency adjustment that can be achieved by frequency adjustment commands.
3.5
Frequencystability
Describe the amount of random fluctuations in the average frequency.
Note. The average time is called the sampling time. Different stability measures correspond to different sampling times.
[Source. JJF1180-2007, 3.23, with modification]
3.6
Temperature sensitivity
The degree to which the output characteristics of the equipment change with temperature within the normal working temperature range.
Note. It is usually expressed as the amount of change in the device signal output characteristics (relative frequency deviation) caused by a unit temperature change (every 1°C change).
3.7
Relative frequency offset relative frequency offset
The difference between the actual frequency value and the nominal frequency value.
[Source. JJF1180-2007, 3.20, with modification]
3.8
Phase noise
The ratio of the power in the unit bandwidth (take 1 Hz) where the single sideband deviates from the signal carrier frequency to the carrier frequency power.
Note. The unit is dBc/Hz. The deviation value from the carrier frequency is called the Fourier frequency, which is generally 1Hz~100kHz.
[Source. JJF1180-2007, 3.31, with modification]
3.9
Harmonic distortion
The ratio of the root mean square value of the target harmonic to the signal electrical average root value.
4 Classification and composition of cesium atomic clock
4.1 Overview
The cesium atomic clock is a passive atomic frequency standard with a cesium atomic beam as the frequency reference. Its working principle is to use a microwave field to interact with cesium atoms.
The function generates a frequency discrimination signal, and the frequency discrimination signal is used to lock the microwave frequency on the ultra-fine energy level of the ground state of the cesium atom, thereby realizing the reference frequency signal
The output signal and the atomic transition frequency have the same level of relative frequency deviation and long-term stability characteristics. Cesium atomic clock main
Including cesium atomic resonator, microwave frequency unit and circuit control unit and other components, as shown in Figure 1.
4.2 Classification of cesium atomic clock products
In order to realize the detection of the atomic state after microwave action, it is necessary to prepare the state of the atomic beam. According to the atomic state preparation and detection method
Different, cesium atomic clocks can be divided into three types. magnetically selected cesium atomic clocks, optically pumped cesium atomic clocks, and magnetically selected optically detected cesium atomic clocks. Magnetically selected cesium atom
Zhong uses the non-uniform magnetic field generated by the state-selective magnet to prepare the atomic state, and uses hot wire ionization and electron multiplier amplification technology to detect atoms
Obtain frequency discriminatory signal; optically pumped cesium atomic clock uses laser pumping technology for atomic state preparation and laser induced fluorescence detection technology for detection
Atomic state; magnetically selected state optical detection cesium atomic clock uses a non-uniform magnetic field generated by a state-selective magnet for atomic state preparation, and uses laser-induced fluorescence detection
Measurement technology detects the atomic state.
According to the different performance requirements, cesium atomic clocks can be divided into standard cesium atomic clocks and high-performance cesium atomic clocks.
4.3 Composition of cesium atomic clock products
4.3.1 Cesium atomic resonator
The cesium atomic resonator is the core part of the cesium atomic clock, which is mainly used to generate a collimated cesium atomic beam in a high vacuum environment. Cesium
The sub-resonator has a built-in microwave resonant cavity. When the atomic beam passes through the resonant cavity, the atomic beam interacts with the microwave field and transitions. Cesium resonance
The device also contains a state detection device for converting the state of the atomic beam into an electrical signal. In the magnetically selected cesium atomic clock, ionizing wires and electrons should be built in
Multiplier isomorphic detection device; for optically pumped cesium atomic clock and magnetic selective state optical detection cesium atomic clock, fluorescence detection device should be built-in.
4.3.2 Microwave frequency unit
The microwave frequency unit mainly includes a voltage-controlled crystal oscillator and a microwave frequency integrated part. The microwave frequency integrated part will oscillate the voltage-controlled crystal
The output signal of the device is frequency multiplied and modulated to generate a microwave excitation signal to be fed into the microwave cavity of the cesium atomic oscillator.
4.3.3 Circuit control unit
The circuit control unit processes the error signal output by the cesium atom resonator and outputs it to the microwave frequency unit to achieve voltage control
Closed loop lock of crystal oscillator.
The circuit control unit monitors the working status of each part of the cesium atomic clock at the same time, and outputs the cesium atomic clock through communication with the host computer.
status information.
4.3.4 Optical unit
In the optically pumped cesium atomic clock, the optical unit outputs two laser beams to prepare and detect the state of the atomic beam.
In the magnetic selective state optical detection cesium atomic clock, the optical unit outputs a laser beam to detect the state of the atomic beam.
5 Technical requirements
5.1 Functional requirements
The cesium atomic clock should have the following functions.
a) Signal output, the cesium atomic clock needs to be able to output 10MHz sine signal and 1PPS pulse signal, and can output 5MHz sine
signal;
b) Automatic closed-loop locking function, the cesium atomic clock can automatically achieve closed-loop locking when it is turned on or restarted after power failure;
c) Frequency adjustment function, the cesium atomic clock should be able to adjust the output frequency through the control panel or adjustment instructions;
d) External synchronization function, the cesium atomic clock should have the function of frequency signal synchronization through the external 1PPS signal;
e) Remote monitoring function, the cesium atomic clock should be able to use the monitoring port to realize the remote monitoring function through the corresponding instructions of the product;
f) Fault detection function, the cesium atomic clock shall have the functions of fault self-checking, fault alarm and uploading of working parameter information.
5.8 Power requirements
The cesium atomic clock should meet the following power consumption requirements.
a) Peak power consumption. ≤150W;
b) Average power consumption. ≤110W.
5.9 Environmental adaptability
Cesium atomic clock products should meet the following environmental adaptability requirements.
a) The storage temperature range meets the storage conditions in the range of -20℃~50℃;
b) Working temperature range, meet the normal working range of 18℃~28℃;
c) Transportation, which can meet the requirements of aviation, road and railway transportation, and pass the vibration test according to GB/T 4857.23-2012.
5.10 Electromagnetic compatibility
Products should meet the following electromagnetic compatibility requirements.
a) The conduction emission characteristics of 10kHz~10MHz power cord should meet the requirements of GB 4824-2019;
b) The 10kHz~400MHz cable bundle injection conduction sensitivity should meet the requirements of GB/T 17626.6-2017;
c) The cable bundle injection pulse excitation conduction sensitivity should meet the requirements of GB/T 17626.4-2018;
d) 10kHz~100MHz cables and power lines are sensitive to damped sinusoidal transient conduction and should meet the requirements of GB/T 17626.12-2013
Claim;
e) 10kHz~18GHz electric field radiation emission shall meet the requirements of GB 4824-2019;
f) The 10kHz~40GHz electric field radiation sensitivity should meet the requirements of GB/T 17626.3-2016.
5.11 Reliability and maintainability requirements
The cesium atomic clock should meet the following reliability and maintainability requirements.
a) Mean time between failures (MTBF) ≥20000h;
b) Lifetime requirements, standard cesium atomic clock life ≥ 8 years, high-performance cesium atomic clock life ≥ 5 years;
c) Mean time to repair (MTTR) ≤ 48h.
6 Test method
6.1 Test environment conditions
Unless otherwise specified, the test should be carried out under the following conditions.
a) Temperature. 18℃~28℃, the maximum allowable temperature change during the test is ±1℃;
b) Relative humidity. 10%~60%;
c) Air pressure. 30kPa~300kPa;
d) Ambient magnetic field. ≤2Gs;
e) Power supply. voltage 220 (1±10%) V, frequency 50 (1±2%) Hz;
f) The instruments, meters, and equipment used in the test should be verified or calibrated, meet the measurement requirements and be within the validity period.
6.2 Test equipment
6.2.1 Reference frequency standard
The reference frequency standard used for cesium atomic clock index test should meet the following requirements.
a) The output frequency includes 5MHz and 10MHz;
b) The frequency stability is better than 1/3 of the frequency stability of the same sampling time of the tested cesium atomic clock;
c) The relative frequency deviation is one order of magnitude better than the measured cesium atomic clock;
d) The phase noise is 10dB smaller than the phase noise at the corresponding frequency deviation of the tested cesium atomic clock.
One or more reference frequency standards can be selected.
6.2.2 Frequency standard comparator
The frequency standard comparator used for cesium atomic clock index test should meet the following requirements.
a) Input frequency, support 5MHz and 10MHz;
b) The uncertainty of the comparison is better than 1/3 of the frequency stability of the same sampling time of the tested cesium atomic clock.
6.2.3 Phase noise measurement device
The phase noise measurement device used for cesium atomic clock index test should meet the following requirements.
a) Input frequency, support 5MHz and 10MHz;
b) Fourier frequency range, up to 1Hz~100kHz;
c) The phase noise background is 10dB smaller than the phase noise of the tested cesium atomic clock at the corresponding Fourier frequency.
6.2.4 Spectrum Analyzer
The spectrum analyzer used for cesium atomic clock index test should meet the following requirements.
a) The frequency range covers 1MHz~50MHz;
b) Dynamic range. ≥100dB.
6.2.5 Oscilloscope
The oscilloscope used for cesium atomic clock index test should meet the following requirements.
a) Bandwidth. ≥1GHz;
b) Sampling rate. ≥3GHz.
6.2.6 Time interval counter
The time interval counter used for cesium atomic clock index test should meet the following requirements.
a) The time interval ranges from 1ns to 1s;
b) The maximum allowable error is ±1ns;
c) The trigger level is continuously adjustable within the range of (0~5)V and can indicate the level value;
d) With external frequency standard function.
6.2.7 Second pulse (1PPS) generator
The second pulse generator used for cesium atomic clock index test should meet the following requirements.
a) Pulse amplitude ≥ 2.4V, meeting TTL level requirements (impedance 50Ω);
b) Pulse width. ≥100ns;
c) Pulse rise time. < 5ns;
d) With external frequency standard function.
6.2.8 High and low temperature test chamber
The high and low temperature test chamber used to test the temperature sensitivity, storage and transportation temperature range, working temperature range and other indicators or characteristics of the cesium atomic clock should be full
6.3.2 Performance Test
6.3.2.1 Relative frequency deviation
Test according to the method specified in 6.2.2.6 of JJG492-2009.
6.3.2.2 Frequency adjustment range
Set the relative output frequency adjustment of the cesium atomic clock to 1E-11, according to the method specified in 6.2.2.7 of JJG492-2009
Test; then set to -1E-11, and test according to the method specified in 6.2.2.7 of JJG492-2009.
6.3.2.3 Frequency adjustment resolution
The frequency adjustment resolution of the tested cesium atomic clock is marked as δy, and the relative output frequency adjustment amount of the tested cesium atomic clock is set to frequency
Adjust c times the resolution so that the relative output frequency is set to c·δy≥1E-13, according to the method specified in 6.2.2.7 of JJG492-2009
carry out testing.
6.3.2.4 Frequency reproducibility
After the cesium atomic clock is turned on and locked, it runs for 0.5h (or the operating time given in the manual), and it is measured according to the direct frequency measurement method (see JJG492-2009)
Measure the relative frequency deviation, the test time is 24h, and the relative frequency deviation y1(τ) is measured; it is turned off for 24h, and after it is turned on and locked again, run for 0.5h
(Or give the running time according to the manual), measure the relative frequency deviation, the test time is 24h, and the relative frequency deviation y2(τ) is measured, according to formula (1)
Calculate frequency reproducibility R.
R=|y2(τ)-y1(τ)| (1)
Where.
R --- frequency reproducibility;
y1(τ), y2(τ)---the relative frequency deviation before and after shutdown;
τ ---Sampling time.
6.3.2.5 Frequency stability
According to the method specified in 6.2.2.4 of JJG492-2009, test the frequency stability of the sampling time from 1s to 100000s; the sampling time is
The frequency stability of 5d can be calculated using at least 10 data points (corresponding to continuous measurement time not less than 50d).
6.3.2.6 Phase noise
Test according to the method specified in 6.2.2.5 of JJG492-2009.
6.3.2.7 Frequency output signal amplitude
Test according to the method specified in 6.2.2.2 of JJG492-2009.
6.3.2.8 Harmonic distortion
Test according to the method specified in 6.2.2.3 of JJG492-2009.
6.3.2.9 Non-harmonic distortion
Test according to the method specified in 6.2.2.3 of JJG492-2009.
6.3.2.10 1PPS signal amplitude
Test according to the method specified in 6.2.2.8 of JJG492-2009.
The communication protocol uses the host computer to communicate with the cesium atomic clock, and the test methods of each communication function are shown in 6.3.4.2~6.3.4.8.
6.3.4.2 Number setting test
Use the cesium atomic clock to monitor the upper computer, change the device number, and query the device number. The device number can be queried, query results and changes
The equipment numbers are the same and should meet the requirements of 5.4.
6.3.4.3 Frequency fine-tuning test
Use the cesium atomic clock to monitor the host computer, change the output frequency of the cesium atomic clock, and fine-tune 100μHz in the positive direction, and use the test of 6.3.2.1
Method, test the relative deviation of frequency before and after fine-tuning the output frequency, the deviation value is equal to 100μHz.
The query frequency fine-tuning parameter should be consistent with the set value.
6.3.4.4 Output frequency selection test
Use the cesium atomic clock to monitor the host computer, change the output frequency of the cesium atomic clock, select 5MHz output, or 10MHz output,
Using the test method of 6.3.1.1, the 5MHz/10MHz signal output by the cesium atomic clock frequency is consistent with the set value.
The query frequency selection parameter should be consistent with the set value.
6.3.4.5 1PPS synchronization test
Using the test method of 6.3.1.4, the upper computer is monitored through the state of the cesium atomic clock, and the 1PPS synchronization command is issued, which can realize the synchronization function and
Should meet synchronization indicators.
6.3.4.6 1PPS output phase adjustment test
Use the cesium atomic clock to monitor the upper computer, change the phase of the output 1PPS of the cesium atomic clock, and use the test method of 6.3.2.14 to test
Trial synchronization error, multiple changes and multiple tests, record the relative synchronization error, the relative synchronization error meets the 1PPS phase change parameter.
Query the 1PPS output phase adjustment parameter, which should be consistent with the set value.
6.3.4.7 1PPS output width test
Use the cesium atomic clock to monitor the host computer, change the pulse width of the cesium atomic clock output 1PPS, and use the test method of 6.3.2.11
Method, measuring 1PPS output width, should be consistent with the changed parameters.
Query 1PPS output width, which should be consistent with the set value.
6.3.4.8 Monitoring status query
Use the cesium atomic clock to monitor the host computer to check the status of the cesium atomic clock. The cesium atomic clock should be able to return the status parameters normally and be locked.
6.3.5 Power adaptability test
According to the provisions of 5.12 in GB/T 6587-2012.
6.3.6 Appearance test
According to the provisions of GB/T 6587-2012, 5.3.
6.3.7 Dimensions and weight
According to the provisions of GB/T 6587-2012 in 5.4.
6.3.8 Power consumption
According to the provisions of GB/T 34094-2017, 4.5.
6.3.10.5 10kHz~18GHz electric field radiation emission
Test according to the test method specified in GB 4824-2019 or equivalent similar index test method.
6.3.10.6 10kHz~40GHz electric field radiation sensitivity
Test according to the test method specified in GB/T 17626.3-2016 or the equivalent test method of similar indicators.
6.3.11 Reliability and maintainability test
6.3.11.1 MTBF
Provide the MTBF analysis report of the tested cesium atomic clock.
6.3.11.2 Life
Provide the life analysis report of the tested cesium atomic clock.
6.3.11.3 MTTR
Provide the MTTR analysis report of the tested cesium atomic clock.
7 Inspection rules
7.1 Description of inspection rules
The inspections stipulated in this rule are divided into appraisal inspections and factory inspections.
7.2 Identification and inspection
In one of the following cases, identification inspection should be carried out.
a) Before the new product type approval;
b) Before the product is transferred to the factory for finalization and appraisal;
c) After the official production, if there are major changes in design, process materials, and components, which may affect product performance;
d) When the product has been stopped for more than one year and resumed production;
e) When the national technical supervision agency or the technical inspection department entrusted by it proposes identification and inspection requirements;
f) When the factory inspection result is significantly different from the previous batch of product inspection;
g) When stipulated in the contract.
7.3 Factory inspection
Each cesium atomic clock product shall be inspected by the inspection department of the manufacturing unit before leaving the factory. The inspection items are shown in Table 9.
7.4 Inspection items
The inspection items are shown in Table 9.According to the specific situation, the user and the manufacturer can negotiate to cut some inspection items or change the inspection order.
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