Low-noise high-stability frequency output device and method
By combining constant temperature crystal and 铷 atom clocks in the time -frequency device, and using FPGA and single -chip microcomputer for simultaneous tame, solve the frequency output difficulties of low noise and high and short -term stability in existing technology, realize low noise and high stability frequency frequency frequency Output, with a good time -conservative function.
Patent Information
- Application Number
- CN202411532066.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-30
- Publication Date
- 2025-01-24
AI Technical Summary
The prior art is difficult to achieve low noise and high short-term stability 10M and 100M frequency signal output in time-frequency equipment, especially the phase noise and short-term stability of rubidium atomic clocks are not high and cannot meet high requirements.
Design a frequency output device with a low noise and high stability, combined with constant temperature crystal and 铷 atomic clocks, and use FPGA units, single -chip machines and TDC units to use external reference 1pps signals to tame the atomic clock and constant temperature crystal to make the frequency synchronization, thereby achieving low low frequency, thereby achieving low frequency, thereby achieving low frequency, thereby achieving low frequency, thereby achieving low frequency, thereby achieving low frequency, thereby achieving low frequencies, so as to achieve low low The frequency output of noise and high stability.
The frequency output of low noise and high stability has been realized, and it has a good time -defense function. It can still maintain high accuracy after disconnecting the reference 1pps and meet the high -requirements time frequency device output.
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Figure CN119363106A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of time and frequency technology, and in particular to a frequency output device and method with low noise and high stability. Background Art
[0002] At present, the time and frequency industry has increasingly higher requirements for the phase noise and short-term stability of the 10M and 100M frequency signals output by time and frequency equipment. To meet the low noise and short-term stability indicators of the frequency, it is necessary to select the corresponding constant temperature crystal oscillator; at the same time, the time and frequency equipment must meet the high-precision timekeeping requirements and must use rubidium atomic clocks with very high long-term stability to ensure it. The phase noise and short-term stability of rubidium atomic clocks are generally not high, and cannot meet the output frequency low noise and high short-term stability indicators. Summary of the invention
[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a frequency output device and method with low noise and high stability.
[0004] The objective of the present invention is achieved through the following technical solutions: A low-noise and high-stability frequency output device, comprising a constant temperature crystal oscillator, a rubidium atomic clock, an FPGA unit, a single-chip microcomputer, a first TDC unit and a second TDC unit; The FPGA unit is connected to the constant temperature crystal oscillator, the rubidium atomic clock, the single-chip microcomputer, the first TDC unit and the second TDC unit. The constant temperature crystal oscillator is also connected to the single-chip microcomputer, and the single-chip microcomputer is also connected to the first TDC unit and the second TDC unit respectively. The FPGA unit is used to receive an external reference signal input from the outside, and transmit the external reference signal to the single-chip microcomputer and the first TDC unit; The first TDC unit and the second TDC unit are used to measure the phase difference of the input time signal; The single chip microcomputer communicates with the first TDC unit and the second TDC unit via the SPI bus, and is used to adjust the frequency of the rubidium clock or the voltage control of the constant temperature crystal oscillator according to the phase difference; The rubidium atomic clock communicates with the FPGA unit via a UART serial port.
[0005] Furthermore, the rubidium atomic clock unit is selected as the XHTF1031 rubidium atomic clock, which meets the long-term stability requirement: ≤5×10 -12 / sky.
[0006] Furthermore, the first TDC unit and the second TDC unit use a time measurement chip of model MS1022 with a measurement accuracy of 20 ps.
[0007] A low-noise and high-stability frequency output method, comprising: Step 1: tame the rubidium atomic clock by externally receiving a reference 1PPS signal, so that the frequency of the rubidium atomic clock is synchronized to the reference 1PPS; Step 2: Generate a local 1PPS signal to tame the oven-controlled crystal oscillator so that the oven-controlled crystal oscillator 10MHz is fully synchronized to the frequency of the rubidium atomic clock.
[0008] Furthermore, the step 1 specifically includes: The FPGA unit receives a reference 1PPS signal from the outside, and sends the reference 1PPS signal to the first TDC unit and the single chip microcomputer respectively; The rubidium atomic clock outputs the original 10MHz signal to the microcontroller. The microcontroller uses the received reference 1PPS as a reference and generates a local 1PPS signal with a phase advance of 50-500ns by counting the original 10MHz signal. The single chip microcomputer sends the local 1PPS signal to the first TDC unit after being beaten by the rubidium atomic clock. The first TDC unit measures the reference 1PPS signal and the local 1PPS signal after being beaten, obtains a first phase difference and outputs it to the single chip microcomputer. The single chip microcomputer adjusts the frequency of the rubidium clock in real time according to the first phase difference, so that the frequency of the rubidium clock is synchronized to the external reference 1PPS.
[0009] Furthermore, the step 2 specifically includes: Sending a first 1PPS signal obtained by beating the local 1PPS signal with the tamed rubidium atomic clock to the second TDC unit; The first 1PPS signal is then beat by a constant temperature crystal oscillator to obtain a second 1PPS signal, and the second 1PPS signal is sent to a second TDC unit; The second TDC unit measures the first 1PPS signal and the second 1PPS signal, obtains a second phase difference and outputs it to the single chip microcomputer; The single chip microcomputer adjusts the voltage control of the constant temperature crystal oscillator in real time according to the second phase difference, so that the constant temperature crystal oscillator 10MHz is completely synchronized to the frequency of the rubidium atomic clock.
[0010] The beneficial effects of the present invention are: 1) The frequency output device of the present invention has a simple structure design, and a general FPGA and a single-chip microcomputer can realize the function. The 1PPS reference signal can be used to tame the device, so that the output frequency has the characteristics of a constant temperature crystal oscillator and a rubidium atomic clock, and has low noise and high stability. 2) The frequency output device of the present invention has a good timekeeping function. After being tamed by 1pps, it still has a high accuracy when disconnected from the reference 1PPS. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1A schematic diagram of the structure of a low-noise and high-stability frequency output device provided by an embodiment of the present invention; Figure 2 Schematic diagram of time difference measurement for taming the rubidium atomic clock; Figure 3 Schematic diagram of the time difference measurement for taming the constant temperature crystal oscillator. DETAILED DESCRIPTION
[0012] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.
[0013] See also Figure 1-Figure 3 , the present invention provides a technical solution: Embodiment 1: A low noise and high stability frequency output device, such as Figure 1 As shown, it includes a constant temperature crystal oscillator, a rubidium atomic clock, an FPGA unit, a single-chip microcomputer, a first TDC unit and a second TDC unit; The FPGA unit is connected to the constant temperature crystal oscillator, the rubidium atomic clock, the single-chip microcomputer, the first TDC unit and the second TDC unit. The constant temperature crystal oscillator is also connected to the single-chip microcomputer, and the single-chip microcomputer is also connected to the first TDC unit and the second TDC unit respectively. The FPGA unit is used to receive an external reference signal input from the outside, and transmit the external reference signal to the single-chip microcomputer and the first TDC unit; The first TDC unit and the second TDC unit are used to measure the phase difference of the input time signal; The single chip microcomputer communicates with the first TDC unit and the second TDC unit via the SPI bus, and is used to adjust the frequency of the rubidium clock or the voltage control of the constant temperature crystal oscillator according to the phase difference; The rubidium atomic clock communicates with the FPGA unit via a UART serial port.
[0014] In this embodiment, the rubidium atomic clock unit is selected as the XHTF1031 rubidium atomic clock, which meets the long-term stability requirement: ≤5×10 -12 / sky.
[0015] The first TDC unit and the second TDC unit use a time measurement chip of model MS1022, with a measurement accuracy of 20ps.
[0016] In addition, the constant temperature crystal oscillator can be selected according to the requirements of phase noise and short-term stability. Dapu's O22B-K425-10.00MHz can be selected; the FPGA resource requirements are not high, and mainstream low-cost chips can be selected. The MCU can choose the mainstream STM32F407 series microcontroller or other similar models.
[0017] Embodiment 2: A low-noise and high-stability frequency output method, comprising: Step 1: tame the rubidium atomic clock by externally receiving a reference 1PPS signal, so that the frequency of the rubidium atomic clock is synchronized to the reference 1PPS; Furthermore, the step 1 specifically includes: The FPGA unit receives a reference 1PPS signal from the outside, and sends the reference 1PPS signal to the first TDC unit and the single chip microcomputer respectively; The rubidium atomic clock outputs the original 10MHz signal to the microcontroller. The microcontroller uses the received reference 1PPS as a reference and generates a local 1PPS signal with a phase advance of 50-500ns by counting the original 10MHz signal. The single chip microcomputer sends the local 1PPS signal to the first TDC unit after being beaten by the rubidium atomic clock. The first TDC unit measures the reference 1PPS signal and the local 1PPS signal after being beaten, obtains a first phase difference and outputs it to the single chip microcomputer. The single chip microcomputer adjusts the frequency of the rubidium clock in real time according to the first phase difference, so that the frequency of the rubidium clock is synchronized to the external reference 1PPS.
[0018] The clock signals involved in step 1 are as follows Figure 2 As shown, the reference 1PPS signal is input to the STOP pin of the first TDC unit, and the local 1PPS signal is input to the START pin of the first TDC unit after being beat by the 10MHz frequency signal of the rubidium atomic clock. The first TDC unit measures the phase difference ∆t1 between the START and STOP signals.
[0019] Step 2: Generate a local 1PPS signal to tame the oven-controlled crystal oscillator so that the oven-controlled crystal oscillator 10MHz is fully synchronized to the frequency of the rubidium atomic clock.
[0020] Furthermore, the step 2 specifically includes: Sending a first 1PPS signal obtained by beating the local 1PPS signal with the tamed rubidium atomic clock to the second TDC unit; The first 1PPS signal is then beat by a constant temperature crystal oscillator to obtain a second 1PPS signal, and the second 1PPS signal is sent to a second TDC unit; The second TDC unit measures the first 1PPS signal and the second 1PPS signal, obtains a second phase difference and outputs it to the single chip microcomputer; The single chip microcomputer adjusts the voltage control of the constant temperature crystal oscillator in real time according to the second phase difference, so that the constant temperature crystal oscillator 10MHz is completely synchronized to the frequency of the rubidium atomic clock.
[0021] The clock signals involved in step 2 are as follows: Figure 3 As shown, the first 1PPS signal obtained by beating the local 1PPS signal with the tamed rubidium atomic clock is input to the START pin of the second TDC unit. The second 1PPS signal obtained by beating the first 1PPS signal with the constant temperature crystal oscillator is input to the STOP pin of the second TDC unit. The second TDC unit measures the phase difference ∆t2 between the START and STOP signals.
[0022] In summary, the frequency output device of the present invention has a simple structural design, and a general FPGA and a single-chip microcomputer can realize the function; the 1PPS reference signal can be used to train the device, so that the output frequency has the characteristics of a constant temperature crystal oscillator and a rubidium atomic clock, with low noise and high stability; the frequency output device of the present invention has a good timekeeping function, and after being trained by 1pps, it still has a high accuracy even if the reference 1PPS is disconnected.
[0023] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.
Claims
1. A low-noise and high-stability frequency output device, characterized in that: It includes a constant temperature crystal oscillator, a rubidium atomic clock, an FPGA unit, a single chip microcomputer, a first TDC unit and a second TDC unit; The FPGA unit is connected to the constant temperature crystal oscillator, the rubidium atomic clock, the single-chip microcomputer, the first TDC unit and the second TDC unit. The constant temperature crystal oscillator is also connected to the single-chip microcomputer, and the single-chip microcomputer is also connected to the first TDC unit and the second TDC unit respectively. The FPGA unit is used to receive an external reference signal input from the outside, and transmit the external reference signal to the single-chip microcomputer and the first TDC unit; The first TDC unit and the second TDC unit are used to measure the phase difference of the input time signal; The single chip microcomputer communicates with the first TDC unit and the second TDC unit via the SPI bus, and is used to adjust the frequency of the rubidium clock or the voltage control of the constant temperature crystal oscillator according to the phase difference; The rubidium atomic clock communicates with the FPGA unit via a UART serial port.
2. A low-noise and high-stability frequency output device according to claim 1, characterized in that: The rubidium atomic clock unit is selected as the XHTF1031 rubidium atomic clock, which meets the long-term stability requirement: ≤5×10 -12 / sky.
3. A low-noise and high-stability frequency output device according to claim 1, characterized in that: The first TDC unit and the second TDC unit use a time measurement chip of model MS1022, with a measurement accuracy of 20ps.
4. A low-noise and high-stability frequency output method, characterized in that: include: Step 1: tame the rubidium atomic clock by externally receiving a reference 1PPS signal, so that the frequency of the rubidium atomic clock is synchronized to the reference 1PPS; Step 2: Generate a local 1PPS signal to tame the oven-controlled crystal oscillator so that the oven-controlled crystal oscillator 10MHz is fully synchronized to the frequency of the rubidium atomic clock.
5. The low-noise and high-stability frequency output method according to claim 1, characterized in that: The step 1 specifically includes: The FPGA unit receives a reference 1PPS signal from the outside, and sends the reference 1PPS signal to the first TDC unit and the single chip microcomputer respectively; The rubidium atomic clock outputs the original 10MHz signal to the microcontroller. The microcontroller uses the received reference 1PPS as a reference and generates a local 1PPS signal with a phase advance of 50-500ns by counting the original 10MHz signal. The single chip microcomputer sends the local 1PPS signal to the first TDC unit after being beaten by the rubidium atomic clock. The first TDC unit measures the reference 1PPS signal and the local 1PPS signal after being beaten, obtains a first phase difference and outputs it to the single chip microcomputer. The single chip microcomputer adjusts the frequency of the rubidium clock in real time according to the first phase difference, so that the frequency of the rubidium clock is synchronized to the external reference 1PPS.
6. A low-noise and high-stability frequency output method according to claim 5, characterized in that: The step 2 specifically includes: Sending a first 1PPS signal obtained by beating the local 1PPS signal with the tamed rubidium atomic clock to the second TDC unit; The first 1PPS signal is then beat by a constant temperature crystal oscillator to obtain a second 1PPS signal, and the second 1PPS signal is sent to a second TDC unit; The second TDC unit measures the first 1PPS signal and the second 1PPS signal, obtains a second phase difference and outputs it to the single chip microcomputer; The single chip microcomputer adjusts the voltage control of the constant temperature crystal oscillator in real time according to the second phase difference, so that the constant temperature crystal oscillator 10MHz is completely synchronized to the frequency of the rubidium atomic clock.