Fast taming method and system based on high-stability OCXO

Abstract

This invention belongs to the field of time-frequency unification and relates to a fast discipline method and system based on a high-stability OCXO. The method includes selecting a primary reference source, inputting the reference signal into a phase-locked loop frequency multiplier for frequency multiplication, and inputting the processed high-frequency reference signal into a high-precision phase measurement module. A monitoring and processing platform controls two frequency standard signals output from the OCXO frequency standard source through a control word. The first frequency standard signal of the first channel is input into a phase-locked loop frequency divider, and the second frequency standard signal is output to the high-precision phase measurement module. The third frequency standard signal of the second channel is directly input into the high-precision phase measurement module to measure the phase difference between the high-frequency reference signal and the second frequency standard signal. The monitoring and processing platform outputs an updated control word through a fast discipline algorithm to correct the OCXO frequency standard source parameters. The fast discipline process continues until the OCXO frequency standard source stabilizes and the phase difference with the reference source converges, ending the fast discipline state.

Description

Technical Field

[0001] This invention belongs to the field of time-frequency unification, and specifically relates to a rapid taming method and system based on a high-stability oven-controlled crystal oscillator (OCXO). Background Technology

[0002] A crystal oscillator is a frequency source that uses a piezoelectric quartz crystal resonator as its core oscillation element. A positive feedback amplifier circuit excites the resonator to oscillate, and the amplified signal outputs a stable frequency signal. Considering that the crystal oscillator frequency drifts with changes in ambient temperature, causing performance degradation, the entire oscillation circuit can be placed in a temperature-controlled bath. While the ambient temperature changes, the bath temperature remains essentially constant, thus greatly improving the temperature stability of the crystal oscillator's frequency. This is called an oven-controlled crystal oscillator (OCXO).

[0003] Besides being affected by temperature, the frequency of a temperature-controlled crystal oscillator also drifts over time. When observing the frequency drift pattern over a longer timescale, the industry refers to this as long-term stability characteristics, also commonly known as aging. Compared to atomic clocks, the long-term stability of crystal oscillators is not very good. The highest-level temperature-controlled crystal oscillators can barely reach the level of a Class II clock, and most can only reach Class III. Therefore, crystal oscillators usually need to be tamed with a higher frequency standard to meet the system requirements.

[0004] Currently, the time and frequency domain primarily employs discipline algorithms based on a single reference source, such as PID, Kalman filtering, and least squares methods. These algorithms integrate measurement techniques with low phase measurement frequencies, resulting in long discipline OCXO times and slow frequency source synchronization convergence speeds. This limits the application areas of time and frequency systems and increases the burden on certain systems, particularly in military applications like fighter jets and aircraft carriers. Therefore, designing a high-precision, fast phase measurement module and implementing a discipline algorithm based on multiple reference sources for OCXOs is a pressing issue. Summary of the Invention

[0005] Addressing the shortcomings of existing technologies, this paper proposes a rapid discipline method and system based on a highly stable OCXO by researching high-precision, fast phase measurement techniques and considering factors such as productivity, integration, device response rate, and market demand. On one hand, it employs capacitor discharge measurement as the foundational technology for the rapid discipline algorithm. On the other hand, it increases the frequency of the reference source through frequency-locked loop (PLL) technology. Combining this with the characteristics of the OCXO and integrating algorithms such as PID and Kalman filtering, a rapid discipline and convergence algorithm for the OCXO frequency standard source is designed, effectively solving the problem of excessively long preparation time for time-frequency sources.

[0006] In a first aspect of the present invention, a rapid taming method based on a highly stable OCXO is provided, the method comprising:

[0007] 101. The monitoring and processing platform selects a primary reference source through a reference source selection algorithm, inputs the reference signal into a phase-locked loop frequency multiplier for frequency multiplication, and inputs the frequency-multiplied high-frequency reference signal into a high-precision phase measurement module.

[0008] 102. The monitoring and processing platform controls the two frequency standard signals output by the OCXO frequency standard source through the control word. The first frequency standard signal of the first channel is input to the phase-locked frequency divider, and the phase-locked frequency divider outputs the divided second frequency standard signal, which is input to the high-precision phase measurement module. The third frequency standard signal of the second channel is directly input to the high-precision phase measurement module.

[0009] 103. The high-precision phase measurement module processes the high-frequency reference signal, the second frequency standard signal, and the third frequency standard signal, and measures the phase difference between the high-frequency reference signal and the second frequency standard signal;

[0010] 104. The high-precision phase measurement module inputs the phase difference into the monitoring and processing platform. The monitoring and processing platform outputs the updated control word through the fast discipline algorithm and corrects the relevant parameters of the OCXO frequency standard source. The fast discipline state ends when the OCXO frequency standard source is stable and the phase difference with the reference source converges.

[0011] In a second aspect of the present invention, a fast discipline system based on a high-stability OCXO is also provided to implement a fast discipline method based on a high-stability OCXO as described in the first aspect of the present invention. The system includes multiple reference sources, an OCXO frequency standard source, a phase-locked loop multiplier, a phase-locked loop divider, a high-precision phase measurement module, and a monitoring and processing platform.

[0012] The multiple reference sources are used to provide reference signals;

[0013] The phase-locked frequency multiplier is used to perform frequency multiplication on the reference signal;

[0014] The OCXO frequency standard source is used to provide two frequency standard signals, including a first frequency standard signal and a second third frequency standard signal;

[0015] The phase-locked frequency divider is used to perform frequency division processing on the first frequency standard signal;

[0016] The high-precision phase measurement module is used to process the high-frequency reference signal after frequency doubling, the second frequency standard signal after frequency division, and the third frequency standard signal, and to measure the phase difference between the high-frequency reference signal and the second frequency standard signal.

[0017] The monitoring and processing platform is used to call the fast discipline algorithm to output the updated control word based on the phase difference output by the high-precision phase measurement module, and to correct the relevant parameters of the OCXO frequency standard source; until the OCXO frequency standard source is stable and the phase difference with the reference source converges, the fast discipline state ends.

[0018] The beneficial effects of this invention are:

[0019] This invention integrates a clock component or device with rapid discipline technology, effectively shortening the preparation time of the device or component and achieving the goal of being ready to use immediately upon power-on. This significantly expands the application scope of the device. It also lays a solid foundation for subsequently improving the timekeeping characteristics of OCXO frequency standard sources and migrating the rapid discipline method to other frequency standard sources. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the rapid taming method based on a highly stable OCXO in an embodiment of the present invention;

[0021] Figure 2 This is a timing diagram illustrating the principle of phase difference measurement in an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the charging process in an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the discharge process in an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of the rapid taming system structure based on a highly stable OCXO in an embodiment of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Figure 1 This is a schematic diagram of the rapid taming method based on a highly stable OCXO in an embodiment of the present invention, as shown below. Figure 1 As shown, the method includes:

[0027] 101. The monitoring and processing platform selects a primary reference source through a reference source selection algorithm, inputs the reference signal into a phase-locked loop frequency multiplier for frequency multiplication, and inputs the frequency-multiplied high-frequency reference signal into a high-precision phase measurement module.

[0028] In this embodiment of the invention, the monitoring and processing platform selects a primary reference source using a reference source selection algorithm. This includes the monitoring and processing platform running a corresponding reference source selection algorithm according to the currently configured reference source selection strategy, selecting a primary reference source from multiple candidate reference sources. The reference source selection algorithm can be any existing reference source-related selection algorithm, and this invention does not impose any specific limitations on it. Alternatively, the monitoring and processing platform can select a primary reference source from multiple reference sources using a selection word. This primary reference source can provide a corresponding reference signal. After the reference signal is input to a phase-locked loop (PLL) frequency multiplier, the PLL performs frequency multiplication on the reference signal to obtain a high-frequency reference signal. This high-frequency reference signal is then input to a high-precision phase measurement module for subsequent judgment.

[0029] The multiple reference sources can include BeiDou / GPS timing, two-way comparison output signals, satellite common-view output signals, and precise network timing output signals. These reference sources can support time synchronization at the nanosecond level, laying the foundation for the timekeeping and rapid discipline of subsequent frequency standard sources.

[0030] 102. The monitoring and processing platform controls the two frequency standard signals output by the OCXO frequency standard source through the control word. The first frequency standard signal of the first channel is input to the phase-locked frequency divider, and the phase-locked frequency divider outputs the divided second frequency standard signal, which is input to the high-precision phase measurement module. The third frequency standard signal of the second channel is directly input to the high-precision phase measurement module.

[0031] In this embodiment of the invention, the monitoring and processing platform uses control words to control the OCXO frequency standard source, which outputs two frequency standard signals, one referred to as the first frequency standard signal and the other as the third frequency standard signal. The first frequency standard signal is then input into a phase-locked frequency divider, which performs frequency division processing on the first frequency standard signal. The second and third frequency standard signals, which are in the same frequency as the high-frequency reference signal after frequency division, are input into a high-precision phase measurement module for subsequent measurement.

[0032] 103. The high-precision phase measurement module processes the high-frequency reference signal, the second frequency standard signal, and the third frequency standard signal after frequency doubling, and measures the phase difference between the high-frequency reference signal and the second frequency standard signal.

[0033] In this embodiment of the invention, the phase difference measurement process is divided into the measurement of three time differences. The large time difference T2 represents the time difference corresponding to the integer number of pulses of the second frequency standard signal in the phase difference pulse. The small time difference T1 represents the phase difference between the first rising edge of the door opening signal and the third frequency standard signal. The small time difference T3 represents the phase difference between the last rising edge of the door closing signal and the third frequency standard signal. The precise phase difference between the high-frequency reference signal and the second frequency standard signal is calculated by the relationship between the three time differences.

[0034] Based on the above division, the high-precision phase measurement module includes a time difference pulse forming circuit, a first time difference measurement circuit, a second time difference measurement circuit, and a third time difference measurement circuit. The time difference pulse forming circuit is used to form a phase difference pulse between the door opening signal and the door closing signal. The first time difference measurement circuit is used to measure the phase difference between the first rising edge of the door opening signal and the third frequency standard signal. The second time difference measurement circuit is used to measure the integer number of pulses of the second frequency standard signal in the phase difference pulse. The third time difference measurement circuit is used to measure the phase difference between the last rising edge of the door closing signal and the third frequency standard signal. Wherein, when the door opening signal is a high-frequency reference signal, the door closing signal is the second frequency standard signal; when the door opening signal is the second frequency standard signal, the door closing signal is the high-frequency reference signal.

[0035] In this embodiment of the invention, the first time difference measurement circuit is used to measure the phase difference between the door opening signal and the third frequency standard signal. This includes starting the quantization clock count of the third frequency standard signal when the rising edge of the door opening signal arrives, charging the capacitor, stopping the charging of the capacitor when the first rising edge of the third frequency standard signal arrives, and starting constant current discharge through the resistor. The capacitor discharge time is extended by using a slow-amplifier circuit. The capacitor voltage is sampled and quantized, and the number of capacitor discharge count pulses is obtained using a counter to calculate the first time difference.

[0036] In this embodiment of the invention, the third time difference measurement circuit is used to measure the phase difference between the closing signal and the third frequency standard signal. This includes starting the quantization clock count of the third frequency standard signal when the last rising edge of the third frequency standard signal arrives, charging the capacitor, stopping the charging of the capacitor when the rising edge of the closing signal arrives, and starting constant current discharge through the resistor. A slow-amplifier circuit is used to extend the capacitor discharge time. The capacitor voltage is sampled and quantized, and the number of capacitor discharge count pulses is obtained using a counter to calculate the second time difference.

[0037] Understandably, in the above embodiments, the capacitor begins discharging the instant charging stops. The processor starts a timer the moment discharge begins, and the timer stops counting when the voltage discharges to a certain level, allowing the measurement of the time difference corresponding to the pulse. This invention extends the first and third time differences, using a fast-charging, slow-discharging method to re-count the extended time, making the discharge time easier to assess and measure. This approach makes the time difference between the assessed high-frequency reference signal and the second frequency standard signal more accurate, laying the foundation for subsequent rapid discipline.

[0038] The high-precision phase measurement module processes the high-frequency reference signal, the second frequency standard signal, and the third frequency standard signal after frequency doubling. The process of measuring the phase difference between the high-frequency reference signal and the second frequency standard signal includes:

[0039] The measurement of large time difference T2 relies on the counting chain recording the number of internal frequency standard pulses, which is then combined with the period of the internal frequency standard. The counting chain starts counting when the rising edge of the high-frequency reference signal is triggered, and stops counting when the rising edge of the frequency-divided second frequency standard signal is triggered. The number of internal frequency standard fill pulses between the two rising edges is counted by the counting chain, and the counting chain is immediately cleared after its value is read.

[0040] The measurement of small time differences T1 and T3 is achieved by charging and discharging a capacitor. First, the small pulse T1 (or T3) left from the large time difference measurement charges the capacitor; the charging process is very fast. Figure 3 As shown in the diagram, T0 corresponds to the duration of the small pulse T1 (or T3). After charging is complete, the capacitor discharges. This discharge process is processed by the circuit to become linear, as shown below. Figure 4 As shown, the discharge time is much longer than the charging time; in this embodiment, the discharge time is 2000 times longer than the charging time. During the discharge process, this embodiment uses a counting method to accurately measure the phase of small pulses, and finally, in conjunction with a large time difference, achieves high-precision phase measurement.

[0041] 104. The high-precision phase measurement module inputs the phase difference into the monitoring and processing platform. The monitoring and processing platform outputs the updated control word through the fast discipline algorithm and corrects the relevant parameters of the OCXO frequency standard source. The fast discipline state ends when the OCXO frequency standard source is stable and the phase difference with the reference source converges.

[0042] In step 104, the monitoring and processing platform outputs the updated control word through a fast discipline algorithm and corrects the relevant parameters of the OCXO frequency standard source, including:

[0043] 401. Perform a weighted harmonic average operation on the output results of the high-precision phase measurement module. Here, 10 output results can be grouped together, and this group of operation results can be input into the discipline algorithm unit of the OCXO.

[0044] 402. The OCXO discipline algorithm selects the corresponding control algorithm based on the discipline time, the prediction accuracy of the OCXO, temperature, electromagnetic environment parameters, and power supply ripple parameters.

[0045] 403. According to the selected control algorithm, calculate and output the current control word for the OCXO frequency, and output the estimated value of the frequency accuracy for the next stage. At this point, a complete taming process is completed; the next taming process starts from step 401.

[0046] In this embodiment of the invention, the monitoring and processing platform can call a fast discipline algorithm, which may include algorithms such as PID and Kalman filtering. The control word can be updated based on the phase difference. The control word is used to control the two frequency standard signals output by the OCXO frequency standard source. Steps 102 to 104 are executed repeatedly until the OCXO frequency standard source stabilizes quickly and the phase difference with the reference source converges quickly, thus completing the fast discipline process.

[0047] In some embodiments, after the rapid taming state ends, a stable taming state can be entered. The specific taming process of the stable taming state can be implemented using existing technologies, and the present invention does not impose specific limitations on it.

[0048] Figure 5 This is a schematic diagram of the fast taming system structure based on a highly stable OCXO in an embodiment of the present invention, as shown below. Figure 5 As shown, the system includes multiple reference sources, an OCXO frequency standard source, a phase-locked loop frequency multiplier, a phase-locked loop frequency divider, a high-precision phase measurement module, and a monitoring and processing platform;

[0049] The multiple reference sources are used to provide reference signals;

[0050] The phase-locked frequency multiplier is used to perform frequency multiplication on the reference signal;

[0051] The OCXO frequency standard source is used to provide two frequency standard signals, including a first frequency standard signal and a second third frequency standard signal;

[0052] The phase-locked frequency divider is used to perform frequency division processing on the first frequency standard signal;

[0053] The high-precision phase measurement module is used to process the high-frequency reference signal after frequency doubling, the second frequency standard signal after frequency division, and the third frequency standard signal, and to measure the phase difference between the high-frequency reference signal and the second frequency standard signal.

[0054] The monitoring and processing platform is used to call the fast discipline algorithm to output the updated control word based on the phase difference output by the high-precision phase measurement module, and to correct the relevant parameters of the OCXO frequency standard source; until the OCXO frequency standard source is stable and the phase difference with the reference source converges, the fast discipline state ends.

[0055] In this embodiment of the invention, the system further includes a reference source selection unit, which is used to select a primary reference source from multiple reference sources.

[0056] Specifically, the high-precision time transmission interface is input to the reference source selection unit, which selects a primary reference source to the phase-locked loop frequency multiplier to multiply the reference signal, forming a high-frequency reference signal that is input to the high-precision phase measurement module. On the other hand, the OCXO frequency standard source outputs two frequency standard signals. One is input to the phase-locked loop frequency divider, which outputs a signal with the same frequency as the high-frequency reference signal to the high-precision phase measurement module, and the other is directly input to the high-precision phase measurement module.

[0057] The high-precision phase measurement module measures the precise phase difference using a capacitor charging method and digital interpolation, and sends this information to the monitoring and processing platform. The platform then outputs control signals to the OCXO via a fast discipline algorithm, enabling the OCXO to stabilize quickly and its phase difference with the reference source to converge rapidly. This achieves the goal of reducing the preparation time of the time-frequency source.

[0058] The core of this solution lies in high-precision phase measurement technology and a fast discipline algorithm running on the monitoring and processing platform. Simultaneously, this solution supports various time synchronization methods at the nanosecond level, such as BeiDou / GPS time synchronization, two-way comparison, satellite common-view, and precise network time synchronization, expanding the application scope of this technology and laying a solid foundation for migrating the fast discipline method to other frequency standard sources, given the timekeeping characteristics of these sources.

[0059] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A rapid taming method based on a highly stable OCXO, characterized in that, The method includes:

101. The monitoring and processing platform selects a primary reference source through a reference source selection algorithm, inputs the reference signal into a phase-locked loop frequency multiplier for frequency multiplication, and inputs the frequency-multiplied high-frequency reference signal into a high-precision phase measurement module.

102. The monitoring and processing platform controls the two frequency standard signals output by the OCXO frequency standard source through the control word. The first frequency standard signal of the first channel is input to the phase-locked frequency divider, and the phase-locked frequency divider outputs the divided second frequency standard signal, which is input to the high-precision phase measurement module. The third frequency standard signal of the second channel is directly input to the high-precision phase measurement module.

103. A high-precision phase measurement module processes a high-frequency reference signal, a second frequency standard signal, and a third frequency standard signal to measure the phase difference between the high-frequency reference signal and the second frequency standard signal. The high-precision phase measurement module includes a time difference pulse forming circuit, a first time difference measurement circuit, a second time difference measurement circuit, and a third time difference measurement circuit. The time difference pulse forming circuit is used to form a phase difference pulse between the door opening signal and the door closing signal. The first time difference measurement circuit is used to measure the phase difference between the first rising edge of the door opening signal and the third frequency standard signal. The second time difference measurement circuit is used to measure the integer number of pulses of the second frequency standard signal in the phase difference pulse. The third time difference measurement circuit is used to measure the phase difference between the last rising edge of the door closing signal and the third frequency standard signal. Wherein, when the door opening signal is a high-frequency reference signal, the door closing signal is the second frequency standard signal; when the door opening signal is the second frequency standard signal, the door closing signal is the high-frequency reference signal. The first time difference measurement circuit is used to measure the phase difference between the door opening signal and the third frequency standard signal. This includes starting the quantization clock count of the third frequency standard signal when the rising edge of the door opening signal arrives, charging the capacitor, stopping the charging of the capacitor when the first rising edge of the third frequency standard signal arrives, and starting constant current discharge through the resistor. The slow discharge circuit is used to extend the capacitor discharge time. The capacitor voltage is sampled and quantized, and the number of capacitor discharge count pulses is obtained using a counter to calculate the first time difference. The third time difference measurement circuit is used to measure the phase difference between the closing signal and the third frequency standard signal. This includes starting the quantization clock count of the third frequency standard signal when the last rising edge of the third frequency standard signal arrives, charging the capacitor, stopping the charging of the capacitor when the rising edge of the closing signal arrives, discharging the capacitor through a constant current resistor, extending the capacitor discharge time by using a slow-amplifier circuit, sampling and quantizing the capacitor voltage, obtaining the number of capacitor discharge count pulses using a counter, and calculating the second time difference.

104. The high-precision phase measurement module inputs the phase difference into the monitoring and processing platform. The monitoring and processing platform outputs the updated control word through the fast discipline algorithm and corrects the relevant parameters of the OCXO frequency standard source. The fast discipline state ends when the OCXO frequency standard source is stable and the phase difference with the reference source converges.

2. The rapid taming method based on a highly stable OCXO according to claim 1, characterized in that, In step 104, the monitoring and processing platform outputs the updated control word through a fast discipline algorithm and corrects the relevant parameters of the OCXO frequency standard source, including:

401. Perform a weighted harmonic average operation on the output of the high-precision phase measurement module, and then input the operation result into the discipline algorithm unit of the OCXO; 402. The OCXO discipline algorithm selects the corresponding control algorithm based on the discipline time, the prediction accuracy of the OCXO, temperature, electromagnetic environment parameters, and power supply ripple parameters.

403. According to the selected control algorithm, calculate and output the current control word for the OCXO frequency, and output the estimated value of the frequency accuracy for the next stage. At this point, a complete taming process is completed; the next taming process starts from step 401.

3. The rapid taming method based on a highly stable OCXO according to claim 2, characterized in that, The control algorithm includes any one of the following: PID control algorithm, Kalman filter algorithm, or least squares method.

4. A rapid taming system based on a highly stable OCXO, characterized in that, It is used to implement a fast discipline method based on a high-stability OCXO as described in any one of claims 1 to 3. The system includes multiple reference sources, an OCXO frequency standard source, a phase-locked multiplier, a phase-locked divider, a high-precision phase measurement module, and a monitoring and processing platform. The multiple reference sources are used to provide reference signals; The phase-locked frequency multiplier is used to perform frequency multiplication on the reference signal; The OCXO frequency standard source is used to provide two frequency standard signals, including a first frequency standard signal and a second third frequency standard signal; The phase-locked frequency divider is used to perform frequency division processing on the first frequency standard signal; The high-precision phase measurement module is used to process the high-frequency reference signal after frequency doubling, the second frequency standard signal after frequency division, and the third frequency standard signal, and to measure the phase difference between the high-frequency reference signal and the second frequency standard signal. The monitoring and processing platform is used to call the fast discipline algorithm to output the updated control word based on the phase difference output by the high-precision phase measurement module, and to correct the relevant parameters of the OCXO frequency standard source; until the OCXO frequency standard source is stable and the phase difference with the reference source converges, the fast discipline state ends.

5. A rapid taming system based on a highly stable OCXO according to claim 4, characterized in that, The multiple reference sources include BeiDou / GPS timing, two-way comparison, satellite common view, and precise network timing.

6. A rapid taming system based on a highly stable OCXO according to claim 4 or 5, characterized in that, The system further includes a reference source selection unit, which is used to select a primary reference source from multiple reference sources.

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