other information
drafter:Wang Yanhui, Zhang Aimin, Jiao Wenhai, Liu Ying, Wang Ji, Zhao Xingwen, Huang Kai
Drafting unit:Peking University, China Institute of Metrology, China Satellite Navigation Engineering Center, 510th Institute of the Fifth Academy of China Aerospace Science and Technology Corporation, Chengdu Tianao Electronics Co., Ltd., 203rd Institute of the S
Focal point unit:National BeiDou Satellite Navigation Standardization Technical Committee (SAC/TC 544)
Proposing unit:Equipment Development Department of the Central Military Commission
Publishing department:State Administration for Market Regulation National Standardization Administration
Some standard content:
ICS17.080
CCSA57
National Standard of the People's Republic of China
GB/T39724—2020
Technical specifications and testing methods for cesium atomic clock2020-12-14Release
State Administration for Market Regulation
National Standardization Administration
2021-07-01Implementation
Normative reference documents
Terms and definitions
Classification and composition of atomic clocks
Classification of atomic clock products
Composition of atomic clock products
Technical requirements
Functional requirements
Performance requirements
Electrical characteristics
Communication function requirements
Power supply requirements
Appearance requirements
Dimension and quality requirements
Power consumption requirements||tt| |Environmental adaptability
Electromagnetic compatibility·
Reliability and maintainability requirements
Test methods
Test environment conditions
Test instruments
Test methods
Inspection rules·
Inspection rule description
Identification inspection
Factory inspection·
Inspection items:
References
GB/T39724—2020
GB/T39724—2020
This document is drafted in accordance with the provisions of GB/T1.1-2020 "Guidelines for Standardization Work Part 1: Structure and Drafting Rules for Standardization Documents".
Please note that some contents of this document may involve patents. The issuing agency of this document does not assume the responsibility 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 units of this document: Peking University, China Institute of Metrology, China Satellite Navigation Engineering Center, Institute 510 of the Fifth Academy of China Aerospace Science and Technology Corporation, Chengdu Tianao Electronics Co., Ltd., Institute 203 of the Second Academy of China Aerospace Science and Industry Corporation. The main drafters of this document: Zhu Yanhui, Zhang Aimin, Jiao Wenhai, Liu Ying, Wang Ji, Zhao Feiwen, Huang Kai. Use
1 Scope
Technical requirements and test methods for atomic clocks
GB/T39724—2020
This document specifies the technical requirements, test methods and inspection rules for the Kai atomic clock (also known as the Brilliant Atomic Frequency Standard) products. This document applies to the development, production and acceptance of Brilliant Atomic Clock products. Normative references
The contents of the following documents constitute the essential terms of this document through normative references in the text. Among them, for dated references, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies to this document.
GB/T1002—2008 Single-phase plugs and sockets for household and similar purposes - Types, basic parameters and dimensions
GB48242019 Limits and measurement methods for radio frequency disturbance characteristics of industrial, scientific and medical equipment - Packaging and transport - Basic tests for packages
Part 23: Random vibration test method
GB/T4857.23—2012
GB/T6587—2012 General specification for electronic measuring instruments GB/T17626.3—2016 Electromagnetic compatibility test and measurement technology GB/T17626.4—2018 Electromagnetic compatibility
Test and measurement technology
GB /T17626.6—2017 Electromagnetic compatibility test and measurement technology GB/T17626.12—2013
GB/T34094—2017
JJG4922009
Terms and definitions
Radio frequency electromagnetic field radiated immunity test
Electrical fast transient pulse group immunity test
Radio frequency field induced conducted disturbance immunity
Ring wave immunity test
Electromagnetic compatibility: test and measurement technology
Method for measuring power consumption of information technology equipment
Atomic frequency standard verification procedure
The following terms and definitions apply to this document. 3.1
magnetic sensitivity
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 as the amount of change in the device signal output characteristics (relative frequency deviation) caused by the unit Gauss change (every change of 1Gs). 3.2
Efrequencyrepeatability
Frequency reproducibility
After the frequency marker has been turned off for a period of time, the frequency value is consistent with the frequency value when it was turned off last time after it is turned on again to achieve stability. Note: It is expressed as the relative frequency difference between two times.
[Source: JJF1180—2007, 3.38, modified] 3.3
frequency setting range
Frequency adjustment range
The frequency output range that can be achieved through the frequency adjustment command. 3.4
Frequency setting resolution
frequency setting resolution The minimum value of frequency adjustment that can be achieved through the frequency adjustment command GB/T39724—2020
Frequency stability frequency stability The amount that describes the random fluctuations of the average frequency
Note: The averaging time is called the sampling time. Different stability measurement values correspond to different sampling times. Source: JJF11802007, 3.23, modified 3.6
Temperature sensitivity temperaturesensitivity The degree to which the output characteristics of the device change with temperature within the normal operating temperature range Note: It is usually expressed in terms of the change in the device signal output characteristics (relative frequency deviation) caused by a unit temperature change (per 1°C change). 3.7
relativefrequency offset
Relative frequency deviation
The difference between the actual frequency value and the nominal frequency value
Note: It is generally expressed as a relative value, such as deviation fo
,. is the nominal value, f is the actual measured value. [Source: JJF1180-2007, 3.20 modified] 3.8
Phase noisephasenoise
The ratio of the power in the unit bandwidth (taken as 1Hz) at the single sideband deviation 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 taken as 1Hz100kHz. [Source: JJF1180-2007, 3.31, modified] 3.9
harmonic distortion
Harmonic distortion
The ratio of the root mean square value of the target harmonic to the root mean square value of the signal level. 4 Classification and composition of atomic clocks
4.1 Overview
Atomic clocks are passive atomic frequency standards that use atomic beams as frequency references. Their working principle is to use the microwave field to interact with atoms to generate a discrimination signal, and use the discrimination signal to lock the microwave frequency to the hyperfine energy level of the atomic ground state, thereby achieving the output of a reference frequency signal. The output signal has the same level of relative frequency deviation and long-term stability characteristics as the atomic transition frequency. Atomic clocks mainly include atomic resonators, microwave frequency units, and circuit control units, as shown in Figure 1. Optical element
Atomic resonator
Microwave frequency unit
Microwave frequency unit
Microwave resonator
Circuit control unit
Figure 1 Basic structure of atomic clocks
Status monitoring
4.2 Classification of atomic clock products
GB/T39724—2020
In order to detect the atomic state after microwave action, it is necessary to prepare the atomic beam. According to the different atomic state preparation and detection methods, atomic clocks can be divided into three categories: magnetically selected atomic clocks, optically pumped atomic clocks, and magnetically selected optical detection atomic clocks. Magnetic selected atomic clocks use the non-uniform magnetic field generated by the state selection magnet to prepare the atomic state, and use hot filament ionization and electron multiplier amplification technology to detect the atomic state to obtain the frequency discrimination signal: optically pumped atomic clocks use laser pumping technology to prepare the atomic state and use laser induced fluorescence detection technology to detect the atomic state; magnetically selected optical detection atomic clocks use the non-uniform magnetic field generated by the state selection magnet to prepare the atomic state and use laser induced fluorescence detection technology to detect the atomic state.
According to the different performance index requirements, atomic clocks can be divided into two categories: standard atomic clocks and high-performance atomic clocks. 4.3 Composition of atomic clock products
4.3.1 Atomic resonator
The atomic resonator is the core part of the atomic clock, which is mainly used to generate a collimated atomic beam in a high vacuum environment. A microwave resonator is built into the atomic resonator. When the atomic beam passes through the resonator, the atomic beam interacts with the microwave field to cause a transition. The atomic resonator also contains a state detection device, which is used to convert the state of the atomic beam into an electrical signal. In the magnetically selected atomic clock, state detection devices such as ionization filaments and electron multipliers should be built in; for optically pumped atomic clocks and magnetically selected optical detection atomic clocks, fluorescence detection devices 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 synthesis part. The microwave frequency synthesis part multiplies and modulates the output signal of the voltage-controlled crystal oscillator to generate a microwave excitation signal and feed it into the microwave resonator of the atomic oscillator. 4.3.3 Circuit control unit
The circuit control unit processes the error signal output by the atomic resonator and outputs it to the microwave frequency unit, thereby realizing the closed-loop locking of the voltage-controlled crystal oscillator
The circuit control unit monitors the working status of each part of the atomic clock at the same time, and outputs the status information of the atomic clock through communication with the host computer.
4.3.4 Optical unit
In the optically pumped atomic clock, the optical unit outputs two laser beams to perform state preparation and state detection on the atomic beam respectively. In the magnetically selected state optical detection atomic clock, the optical unit outputs one laser beam to perform state detection on the atomic beam. 5 Technical requirements
Functional requirements
The atomic clock should have the following functions:
Signal output, the atomic clock needs to be able to output 10MHz sinusoidal signal and 1PPS pulse signal. It can output 5MHz sinusoidal a)
Signal:;
Automatic closed-loop locking function, the atomic clock can automatically restart when it is turned on or powered off. Achieve closed-loop locking; b)
c) Frequency adjustment function, the Yan atomic clock should be able to adjust the output frequency through the control panel or adjustment instructions; d)
External synchronization function, the Yan atomic clock should have the function of frequency signal synchronization through an external 1PPS signal; e)
Remote monitoring function, the Kai atomic clock should be able to use the monitoring port to achieve remote monitoring function through the corresponding product instructions; f)
Fault detection function, the Yan atomic clock should have the functions of fault self-detection, fault alarm and working parameter information upload 3
GB/T39724—2020
Performance Requirements
Atomic clock products should meet the performance requirements shown in Table 1 Table 1
Atomic clock product performance index requirements
Relative frequency deviation
Frequency adjustment range
Frequency adjustment resolution
Frequency reproducibility
10MHz, 5MHz sine signal amplitude
Harmonic distortion (10MHz5MHz)
Non-harmonic distortion (10MHz, 5MHz)
1PPS signal amplitude
1PPS signal width
1PPS signal rise time
1PPS signal jitter Dynamic
1PPS signal synchronization error
1PPS signal phase consistency
Temperature sensitivity
(18℃~28℃)
Magnetic field sensitivity (0~2Gs)
Lock time
Standard type
Better than ±1E-12
Indicator requirements
Better than ±1E-11
≤1E-15
≤2E-13
High performance type
Better than ±5E-13
13dBm±1dBm (impedance 50Q)
-40 dBe
≤-80dBc
High level voltage V. satisfies 2.4V≤V≤5.0VLow level voltage V satisfies 0.0V≤Vi≤0.7V (impedance 50Ω)
20s±1s
≤1nsRMS
Better than ±50ns
Standard type
≤1E-13/℃
2E-13/Gs
Relative frequency deviation is better than 1E-12, which means that the relative frequency deviation in the range of -1E-12 to 1E-12 meets the index requirements. Relative frequency deviation is better than ±5E-13, which means that the relative frequency deviation in the range of -5E-13 to 5E-13 meets the index requirements. Frequency adjustment range is better than ±1E-11, which means that the positive and negative frequency adjustment ranges should be greater than 1E-11. High performance type
≤5E-14/℃
The output 10MHz signal should meet the frequency stability requirements in Table 2 and the single-sideband phase noise requirements in Table 3. Table 2
Sampling time
Frequency stability index requirements of atomic clock productsStandard type
≤1.2E-11
≤8.5E-12
≤2.7E-12
≤8.5E-13
High performance type
≤5.0E-12
≤3.5E-12
≤8.5E-13
≤2.7E-13
Sampling time
10000 s
Fourier frequency at
100kHz
Electrical characteristics
Table 2 (continued)
Standard type
≤2.7E-13
≤8.5E-14
≤5.0E-14
Phase noise index requirements for atomic clock productst(f)
GB/T39724—2 020
High performance type
≤8.5E-14
≤2.7E-14
≤1.0E-14
≤-100dBc/Hz
—130dBc/Hz
≤-145dBc/Hz
-150dBc/Hz
≤ -154dBc/Hz
≤-154dBc/Hz
Atomic clock products should meet the electrical characteristics requirements as shown in Table 4 Table 4
Electrical performance
Frequency signal output
Pulse per second signal output (1PPS)
1PPS synchronization signal input
Communication function requirements
Communication interface and function requirements
Electrical characteristics requirements for atomic clock products
N-type female connector (50Q)
BNC female connector (50Q)
BNC female connector (50Q)
Atomic clocks should have RS-232C asynchronous serial port communication functions, including number setting, frequency fine-tuning, output frequency selection, 1PPS synchronization, 1PPS output phase adjustment, 1PPS output width adjustment and monitoring status query functions. 5.4.2
Communication rate and byte frame structure
The baud rate is 115200; the byte frame structure is 1 start bit\0", 8 data bits, 1 stop bit\1", no parity bit; the low bit is in front and the high bit is in the back. See Table 5.
GB/T39724—2020
Baud rate
115200
5.4.3 Data frame format description
Table 5 RS-232C asynchronous serial communication speed and byte frame structure Start bit
Data bit
Check bit
Stop bit
A complete frame of data consists of a frame header, device number, command number, data length, data content, checksum, and frame tail. For specific requirements, see Figure 2.
Device number Command number
0010001100100100
00001ia0a00
Figure 2 Frame format for atomic clock and host computer communication The following is a specific description of the content of each byte: Frame header: The frame header is at the beginning of each data frame, consisting of two bytes, fixed to 0x23, 0x24. a
Device number: consists of one byte, ranging from 0 to 255. When the device number received by the Yan atomic clock is consistent with the device number of the Yan atomic clock b)
, the command is valid. When the number is 255, it is only valid when changing the device number of the atomic clock and querying the device number of the Kai atomic clock.
Command number: used to select the command, the length is 1 byte. Length: used to represent the length N of the transmitted data content, in bytes: the data length is different according to different command numbers. d)
Data: the real data that needs to be transmitted in a command. The real data is transmitted in big-endian format, that is, the high byte is in front and the low byte is in the back. The data content is different according to different command numbers. f)
Check: consists of one byte, and the check value is the result of the XOR operation on the data content. g)
Tail: consists of two bytes, fixed to 0x21, 0x20. Power supply requirements
The atomic clock shall meet the following power supply requirements:
Rated voltage: 220V, allowable range: rated value ± 10%; b)
Rated frequency: 50Hz. Allowable range: rated value + 2%. The power connector is a single-phase two-pole grounding plug, which complies with the provisions of GB/T1002-2008. 5.6 Appearance requirements
The name and model of the atomic clock shall be marked on the front panel, and an indicator light shall be provided to display the working status of the whole machine. The rear panel shall have frequency signal and 1PPS signal output interfaces, 1PPS synchronization signal input interfaces and grounding terminals, etc. 5.7 Dimensions and quality requirements
The dimensions and quality of the atomic clock shall meet the following requirements: a) Dimensions: The height of the whole machine is ≤4U;
b) Quality: ≤40kg.
Note: The height of 4U is 17.78cm.
5.8 Power consumption requirements
The atomic clock should meet the following power consumption requirements: a) Peak power consumption: ≤150W;
b) Average power consumption: ≤110W.
Environmental adaptability
The atomic clock products should meet the following environmental adaptability requirements: a) Storage temperature range, meet the storage conditions within the range of 20℃～50℃; b) Working temperature range, meet the normal operation within the range of 18℃～28℃; GB/T39724—2020
c) Transportation, can meet the requirements of aviation, road and railway transportation, and pass the vibration test required by GB/T4857.23-2012. Electromagnetic compatibility
The product shall meet the following electromagnetic compatibility requirements: The conducted emission characteristics of the power line of 10kHz~10MHz shall meet the requirements of GB4824-2019; a)
The conducted sensitivity of the cable bundle injection of 10kHz~400MHz shall meet the requirements of GB/T17626.6-2017; b)
The conducted sensitivity of the cable bundle injection pulse excitation shall meet the requirements of GB/T17626.4-2018; The conducted sensitivity of the damped sinusoidal transient of the cable and power line of 10kHz~100MHz shall meet the requirements of GB/T17626.12-2013; d)
The electric field radiated emission of 10kHz~18GHz shall meet the requirements of GB4824-2019; The electric field radiated sensitivity of 10kHz~40GHz shall meet the requirements of GB/T17626.3-2016. Reliability and maintainability requirements
Yan atomic clocks should meet the following reliability and maintainability requirements: mean time between failures (MTBF) ≥ 20000h; a)
life requirements, the life of standard atomic clocks ≥ 8 years, and the life of high-performance atomic clocks ≥ 5 years; c)
mean time to repair (MTTR) ≤ 48h. 6
Test method
Test environment conditions
Unless otherwise specified, the test shall be carried out under the following conditions: a)
Temperature: 18℃~28℃. The maximum allowable temperature change during the test is ±1℃; Relative humidity: 10%~60%;
Air pressure: 30kPa~300kPa
Environmental magnetic field: ≤2Gs;
Power supply: voltage 220 (110%) V. Frequency 50 (1±2%) Hz; The instruments, meters and equipment used in the test shall be verified or calibrated to meet the measurement requirements and Within the validity period 6.2 Test instruments
6.2.1 Reference frequency standard
The reference frequency standard used for the atomic clock index test shall meet the following requirements 7
GB/T39724—2020
The output frequency includes 5MHz and 10MHz;
The frequency stability is better than 1/3 of the frequency stability of the atomic clock under test at the same sampling time; b)
The relative frequency deviation is better than that of the atomic clock under test by one order of magnitude; c)
The phase noise is 10dB less than the phase noise of the atomic clock under test at the corresponding frequency deviation. d)
One or more reference frequency standards can be selected. 6.2.2 Frequency Standard Comparator
The frequency standard comparator used for atomic clock index test shall meet the following requirements: a) Input frequency, support 5MHz and 10MHz; b) Comparison uncertainty is better than 1/3 of the frequency stability of the atomic clock under test at the same sampling time. 6.2.3 Phase Noise Measurement Device
The phase noise measurement device used for atomic clock index test shall meet the following requirements: Input frequency, support 5MHz and 10MHz;
Fourier frequency range, up to 1Hz～100kHz; b)
Phase noise floor, 10dB less than the phase noise of the atomic clock under test at the corresponding Fourier frequency point. c
6.2.4 Spectrum Analyzer
The spectrum analyzer used for atomic clock index test shall meet the following requirements: Frequency range covers 1MHz~50MHz;
Dynamic range: ≥100dB.
6.2.5 Oscilloscope
The oscilloscope used for atomic clock index test shall meet the following requirements: a) Bandwidth: ≥1GHz; www.bzxz.net
b) Sampling rate: ≥3GHz.
6.2.6 Time interval counter
The time interval counter used for atomic clock index test shall meet the following requirements: a) The time interval range is 1ns～1s;
The maximum allowable error is ±1ns;
The trigger level is continuously adjustable in the range of (0～5)V and can indicate the level value: c)
d) It has the function of external frequency standard.
1PPS pulse generator
The 1PPS pulse generator used for atomic clock index test shall meet the following requirements: a)
Pulse amplitude ≥2.4V. Meet TTL level requirements (impedance 50Ω); pulse width: ≥100ns;
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 atomic clocks shall meet the following requirements:
a) The set temperature range of the high and low temperature test chamber covers 20℃～+50℃, and the temperature deviation is ±2℃; b)
The internal temperature gradient of the high and low temperature test chamber is ≤2℃; c
The temperature fluctuation of the high and low temperature test chamber is ≤1℃; d) The heating and cooling rate is lower than 1℃/min.
6.2.9 Three-dimensional Helmholtz coil
The three-dimensional Helmholtz coil used to test the magnetic field sensitivity index of the atomic clock should meet the following requirements: a) The effective working area is not less than 0.8m;
b): The magnetic field intensity in each direction is not less than 2Gs. 6.3 Test method
6.3.1 Function test
Signal output
Atomic clock under test
5 MHz or 10 >Hz
Figure 3 Schematic diagram of signal output test
Oscilloscope
GB/T39724—2020
The schematic diagram of the signal output test method is shown in Figure 3. The output signal of the atomic clock under test is connected to the oscilloscope, and the input impedance of the oscilloscope is selected as 502.Directly measure the frequency signal and pulse per second signal of the atomic clock. The signals detected on the oscilloscope should be the set 10MHz or 5MHz and 1PPS signals.
6.3.1.2 Automatic closed-loop locking
The atomic clock under test is closed-loop locked within 60 minutes after power-on. The closed-loop locking status information is read through the panel or the corresponding product instructions. 6.3.1.3
Frequency adjustment
Use the debugging interface to adjust the frequency through instructions, and verify the frequency adjustment function according to the method specified in 6.2.2.7 of JJG492-2009.
6.3.1.4 External synchronization
Test according to the method specified in 6.2.2.10 of JJG492-2009. 6.3.1.5 Remote monitoring
The atomic clock under test is connected to the host computer through the RS-232C asynchronous serial port, sends corresponding product instructions, observes the product operation status, and realizes the remote monitoring function
6.3.1.6 Fault detection
The atomic clock under test can read fault self-check information, fault alarm information and upload working parameters through the panel or product corresponding instructions.
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