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Basic dataStandard 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 contentsPreface 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 21ForewordThis 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 clock1 ScopeThis 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 referencesThe 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 Regulation3 Terms and definitionsThe 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 clock4.1 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 requirements5.1 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 method6.1 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 JJG4......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB/T 39724-2020_English be delivered?Answer: Upon your order, we will start to translate GB/T 39724-2020_English as soon as possible, and keep you informed of the progress. 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