Clock Stability Evaluation Method, Device and Medium

Abstract

The present invention discloses a method, device and medium for evaluating clock stability. The method includes: using the crystal oscillator to be measured as the internal clock of a first receiver, obtaining observation data by capturing and tracking satellite signals, where the observation data reflects the clock characteristics of the crystal oscillator to be measured; using a second receiver with an external time-frequency reference source as the local clock to obtain observation data; performing time transfer calculation on the observation data of the first receiver and the second receiver and the broadcast ephemeris to obtain the receiver clock error; processing the receiver clock error through the deviation to evaluate and analyze the frequency stability of the crystal oscillator to be measured. The present invention can be realized only through data processing and statistical analysis using the differential precise time transfer technology, without the need for high-precision time and frequency detection and analysis equipment; by combining the differential precise time transfer technology with the modified Allan deviation, the time reference stability of the atomic clock / crystal oscillator to be measured can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-precision time-frequency transfer of the Global Navigation Satellite System (GNSS), and more specifically, relates to a method, device, and medium for evaluating clock stability. Background Art

[0002] Atomic clocks and crystal oscillators are widely used in many fields such as communication, navigation, and time synchronization due to their high-precision characteristics. The frequency stability of atomic clocks and crystal oscillators is an important indicator for evaluating their applicable scenarios, which depends on whether the signal frequencies generated by them remain stable under various environmental conditions. With the continuous progress of technology, some high-precision time-frequency application scenarios have put forward more stringent requirements for performance indicators such as the frequency stability of crystal oscillators.

[0003] The Global Navigation Satellite System (GNSS) is a space-based radio positioning system, mainly including the Global Positioning System (GPS) of the United States, Beidou (BDS) of China, GLONASS of Russia, and Galileo of Europe. In the field of time service, using a GNSS receiver for time service has the characteristics of high precision, low cost, and stability, and time service receivers will be more and more widely used in the field of time service. When a GNSS time service receiver is used in high-precision time-frequency applications, it is necessary to analyze the clock frequency stability, and the purpose is to accurately control the crystal oscillator using a clock taming model. In addition, in the case of satellite navigation signal interruption, in order to more accurately simulate and predict the state of the crystal oscillator clock, it is necessary to accurately understand the characteristics such as the frequency stability of the crystal oscillator clock.

[0004] The GNSS time service receiver performs one-way time service, and its accuracy depends on the accuracy of the satellite ephemeris product. For the pseudo-range single-point positioning technology, the accuracy of the receiver clock error calculated using the broadcast ephemeris is about 20 nanoseconds. Combining the precise single-point positioning technology with carrier phase observations, the accuracy of the receiver clock error calculated using precise satellite orbits and clock differences is about 0.2 nanoseconds. In high-precision data processing, through carrier phase differential observations, not only errors such as ephemeris residuals and atmospheric residuals can be eliminated, but also the integer characteristics of the double-difference integer ambiguity are restored, and time-frequency services at the picosecond level can be quickly realized. Using carrier phase differential time transfer, the receiver receives the observation value information of the reference station from the network side, avoiding the disadvantages of relying on precise satellite orbits and clock difference products. Summary of the Invention

[0005] The present invention is provided to solve the above problems existing in the prior art. Therefore, a clock stability evaluation method, device and medium are needed to further improve the evaluation accuracy of the clock stability of atomic clocks and crystal oscillators. The present invention provides a clock stability evaluation method based on differential precise time transfer. In this method, the crystal oscillator OCXO to be measured is used as the internal clock of GNSS receiver A, and then the observation data is obtained by capturing and tracking satellite signals, and this observation data reflects the clock characteristics of the crystal oscillator OCXO to be measured. On the other hand, GNSS receiver B is externally connected to a time-frequency reference source as the local clock to obtain observation data. Then, the observation data and broadcast ephemeris of the two receivers are used for DPT time transfer solution to obtain the receiver clock offset, and this clock offset result reflects the difference between the time represented by the crystal oscillator OCXO to be measured and the time-frequency reference source. Finally, the frequency stability of the crystal oscillator OCXO to be measured is evaluated and analyzed through Allan deviation.

[0006] Compared with the method of evaluating clock stability by time transfer using the pseudorange single-point positioning technology and the precise point positioning technology combined with carrier phase observations, the present invention further improves the evaluation accuracy of clock stability through the fixing of the inter-station single-difference carrier phase ambiguity, making the obtained results more referenceable.

[0007] According to the first aspect of the present invention, a clock stability evaluation method is provided, and the method includes:

[0008] Taking the crystal oscillator to be measured as the internal clock of the first receiver, and obtaining observation data by capturing and tracking satellite signals, where the observation data reflects the clock characteristics of the crystal oscillator to be measured;

[0009] Taking the second receiver externally connected to a time-frequency reference source as the local clock to obtain observation data;

[0010] Performing DPT time transfer solution on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain the receiver clock offset, where the receiver clock offset reflects the difference between the time represented by the crystal oscillator to be measured and the time-frequency reference source;

[0011] Processing the receiver clock offset through deviation to evaluate and analyze the frequency stability of the crystal oscillator to be measured.

[0012] Further, both the first receiver and the second receiver are GNSS receivers.

[0013] Further, the time-frequency reference source is UTC(k) or a high-precision atomic clock.

[0014] Further, performing DPT time transfer solution on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain the receiver clock offset includes:

[0015] The single-difference pseudorange and carrier-phase observations for any frequency f are shown in Equation (1):

[0016]

[0017] where represents the receiver clock bias between the time-frequency reference station and the user station, c is the speed of light, and the floating single-difference carrier-phase ambiguity of the reference satellite i in Equation (1) is calculated based on the pseudorange and carrier-phase observations and the carrier-phase single-difference ambiguity of other visible satellites j is obtained through Equation (2)

[0018]

[0019] Combining the single-difference ambiguity in Equation (2) and the single-difference carrier-phase observation equation, the receiver clock bias between stations is determined as shown in Equation (3):

[0020]

[0021] Determine the single-difference pseudorange and carrier-phase dual-frequency IF combination observations as shown in Equation (4):

[0022]

[0023] By subtracting the ionosphere-free combination double-difference pseudorange observation from the carrier-phase observation, the ionosphere-free combination double-difference floating ambiguity is obtained:

[0024]

[0025] Using the floating single-difference carrier-phase ambiguity of the reference satellite i in Equation (5) and obtaining the single-difference carrier-phase ambiguity of other visible satellites j through Equation (6)

[0026]

[0027] According to the single-difference ambiguity and the single-difference carrier-phase observation equation, the receiver clock bias between stations is determined as shown in Equation (7):

[0028]

[0029] Furthermore, performing DPT time transfer solution on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain the receiver clock bias further includes:

[0030] Obtaining the time difference result between stations for each visible satellite through the single-frequency solution of Equation (3) or the dual-frequency IF combination solution of Equation (7).

[0031] Further, performing DPT time transfer solution on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain receiver clock error further includes:

[0032] While setting the satellite elevation cut-off angle, using the W j = θ j weighting method to obtain the time transfer result as shown in Equation (8):

[0033]

[0034] where T f represents the differential single-frequency carrier phase time-frequency transfer result, and T IF represents the differential dual-frequency IF combined carrier phase time-frequency transfer result.

[0035] Further, processing the receiver clock error based on the modified Allan deviation to evaluate and analyze the frequency stability of the crystal oscillator to be measured:

[0036] According to the second technical solution of the present invention, a clock stability evaluation device is provided, and the device includes:

[0037] A first observation module configured to use the crystal oscillator to be measured as the internal clock of the first receiver and obtain observation data by capturing and tracking satellite signals, where the observation data reflects the clock characteristics of the crystal oscillator to be measured;

[0038] A second observation module configured to use an externally connected time-frequency reference source of the second receiver as the local clock to obtain observation data;

[0039] A receiver clock error calculation module configured to perform DPT time transfer solution on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain receiver clock error, where the receiver clock error reflects the difference between the time represented by the crystal oscillator to be measured and the time-frequency reference source;

[0040] A stability evaluation module configured to process the receiver clock error through deviation to evaluate and analyze the frequency stability of the crystal oscillator to be measured.

[0041] Further, the receiver clock error calculation module is further configured to:

[0042] The single-difference pseudorange and carrier phase observations for any frequency f are as shown in Equation (1):

[0043]

[0044] where represents the receiver clock error between the time-frequency reference station and the user station, and c is the speed of light;

[0045] Calculate the floating-point single-difference carrier phase ambiguity of the reference satellite i in Equation (1) based on the pseudorange and carrier phase observations And obtain the carrier phase single-difference ambiguity of other visible satellites j through Equation (2)

[0046]

[0047] Combine the single-difference ambiguity in Equation (2) And the single-difference carrier phase observation equation to determine the receiver clock difference between stations as shown in Equation (3):

[0048]

[0049] Determine the single-difference pseudorange and carrier phase dual-frequency IF combined observations as shown in Equation (4):

[0050]

[0051] By subtracting the ionosphere-free combined double-difference pseudorange observation from the carrier phase observation, obtain the ionosphere-free combined double-difference floating-point ambiguity:

[0052]

[0053] Use the floating-point single-difference carrier phase ambiguity of the reference satellite i in Equation (5) And obtain the single-difference carrier phase ambiguity of other visible satellites j through Equation (6)

[0054]

[0055] According to the single-difference ambiguity And the single-difference carrier phase observation equation, determine the receiver clock difference between stations as shown in Equation (7):

[0056]

[0057] According to the third technical solution of the present invention, a readable storage medium is provided. The readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the method described above.

[0058] The present invention has at least the following beneficial effects:

[0059] (1) The present invention has good usability: By realizing picosecond-level time transfer through the single-difference between carrier phases between stations, the frequency stability performance of the crystal oscillator clock and the atomic clock can be further evaluated;

[0060] (2) Real-time performance: The present invention can accurately estimate the inter-station clock offset in real time at the receiver and can also evaluate the frequency stability result of the clock in real time;

[0061] (3) Strong scalability: The present invention can meet the high-precision frequency stability evaluation in static and dynamic scenarios; it can also be used for the frequency stability evaluation of remote clocks when introducing real-time precise satellite orbits. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 shows the overall flowchart of a clock stability evaluation method according to an embodiment of the present invention;

[0063] Figure 2 shows the structural diagram of a clock stability evaluation device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below in conjunction with the drawings and specific embodiments. The embodiments of the present invention will be further described in detail below in conjunction with the drawings and specific examples, but it is not a limitation to the present invention. For the various steps described herein, if there is no necessity for a front-back relationship between them, the order in which they are described as examples herein should not be regarded as a limitation. Those skilled in the art should know that they can be adjusted in order as long as the logic between them is not destroyed and the entire process cannot be implemented.

[0065] Figure 1 shows the overall flowchart of a clock stability evaluation method according to an embodiment of the present invention. As Figure 1 shown, an embodiment of the present invention provides a clock stability evaluation method, which includes steps 1-step 5, and is introduced in detail as follows:

[0066] Step 1:

[0067] Take the oscillator under test OCXO as the internal clock of the GNSS receiver A, and then obtain the observation data by capturing and tracking satellite signals. The observation data reflects the clock characteristics of the oscillator under test OCXO. Note that at this time, the oscillator OCXO is in a free-running clock state.

[0068] Step 2:

[0069] The GNSS receiver B is externally connected to a time-frequency reference source as the local clock to obtain the observation data. The time-frequency reference source can select UTC(k) or a high-precision atomic clock.

[0070] Step 3: Differential precise time transfer method

[0071] Perform single-difference solution between stations for pseudorange and carrier phase observations. The single-difference pseudorange and carrier phase observations for any frequency f are shown in Equation (1).

[0072]

[0073] Where represents the receiver clock bias between the time-frequency reference station and the user station.

[0074] After fixing the double-difference carrier phase ambiguity through RTK technology, use the pseudorange and carrier phase observations to calculate the floating single-difference carrier phase ambiguity of the reference satellite i in Equation (1) and obtain the carrier phase single-difference ambiguity of other visible satellites j through Equation (2)

[0075]

[0076] To obtain the accurate time difference between two stations, combine the single-difference ambiguity in Equation (2) and the single-difference carrier phase observation equation. The receiver clock bias between stations is shown in Equation (3).

[0077]

[0078] For short baselines of several kilometers, errors such as single-difference ephemeris error residuals, single-difference tropospheric delay residuals, and single-difference ionospheric delay residuals are ignored. As the baseline length increases, the error caused by ionospheric delay is one of the main errors affecting time transfer accuracy. The ranging error caused by the ionosphere can reach errors of meters or even hundreds of meters. If the ionospheric delay in the observations is not corrected, it will have a huge impact on the accuracy and reliability of the satellite navigation time transfer results. For longer baselines, this paper uses the dual-frequency ionosphere-free combination to eliminate the first-order term delay effect of the ionosphere. The single-difference pseudorange and carrier phase dual-frequency IF combination observations are shown in Equation (4).

[0079]

[0080] By taking the difference between the ionosphere-free combination double-difference pseudorange observation and the carrier phase observation, obtain the ionosphere-free combination double-difference floating ambiguity.

[0081]

[0082] Furthermore, use the floating single-difference carrier phase ambiguity of the reference satellite i in Equation (5) and obtain the single-difference carrier phase ambiguity of other visible satellites j through Equation (6)

[0083]

[0084] Single-difference ambiguity combined with the above formula Combined with the single-difference carrier-phase observation equation, the receiver clock difference between stations is shown in Equation (7).

[0085]

[0086] Through the single-frequency solution of Equation (3) or the dual-frequency IF combination solution of Equation (7), the time difference results between stations for each visible satellite can be obtained. For the time difference solutions between stations of multiple satellites, how to reasonably determine the weights is the key to improving the accuracy of single-difference carrier-phase time-frequency transfer. While setting the satellite cut-off elevation angle, the weights are determined based on the satellite elevation angle weighting method to determine the single-difference carrier-phase time-frequency transfer results. Here, the weighting method of W j = θ j / 90° is used to obtain the time transfer results as shown in the following formula.

[0087]

[0088] where T f represents the differential single-frequency carrier-phase time-frequency transfer result, and T IF represents the differential dual-frequency IF combined carrier-phase time-frequency transfer result.

[0089] Step 4: Perform DPT time transfer solution on the observation data and broadcast ephemeris of the two receivers through Step 3 to obtain the receiver clock difference, and this clock difference result reflects the difference between the time represented by the crystal oscillator to be measured and the time-frequency reference source.

[0090] Step 5: Process the receiver clock difference through the modified Allan deviation to evaluate and analyze the measurement of the frequency stability of the crystal oscillator to be measured.

[0091] Next, the embodiments of the present invention will further illustrate the feasibility and progressiveness of the present invention in combination with specific calculation examples.

[0092] Select the national atomic time scale measurement reference UTC(NIM) of the National Institute of Metrology, China, as the frequency reference source, and use the DPT method to evaluate and analyze the frequency stability of the crystal oscillator OCXO clock. The specific experimental scheme is as follows:

[0093] (1) Obtain the time transfer result of the crystal oscillator OCXO clock relative to UTC(NIM) through carrier-phase differential precise time transfer; (2) Obtain the result of the second pulse output by the crystal oscillator OCXO clock relative to UTC(NIM) through a time interval counter and convert it into a frequency error.

[0094] The results obtained by the two schemes are analyzed through the modified Allan deviation to obtain the evaluation result of the frequency stability of the crystal oscillator OCXO clock during the free oscillation process.

[0095] An embodiment of the present invention provides a clock stability evaluation device, as Figure 2 shown. The device 200 includes:

[0096] A first observation module 201, configured to use the crystal oscillator to be measured as the internal clock of the first receiver, and obtain observation data by capturing and tracking satellite signals, where the observation data reflects the clock characteristics of the crystal oscillator to be measured;

[0097] A second observation module 202, configured to use the external time-frequency reference source of the second receiver as the local clock to obtain observation data;

[0098] A receiver clock offset calculation module 203, configured to perform DPT time transfer solution on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain the receiver clock offset, where the receiver clock offset reflects the difference between the time represented by the crystal oscillator to be measured and the time-frequency reference source;

[0099] A stability evaluation module 204, configured to process the receiver clock offset through the deviation and evaluate and analyze the frequency stability of the crystal oscillator to be measured.

[0100] In some embodiments, both the first receiver and the second receiver are GNSS receivers.

[0101] In some embodiments, the time-frequency reference source is UTC(k) or a high-precision atomic clock.

[0102] In some embodiments, the receiver clock offset calculation module is further configured to:

[0103] The single-difference pseudorange and carrier phase observations for any frequency f are shown in Equation (1):

[0104]

[0105] where represents the receiver clock offset between the time-frequency reference station and the user station;

[0106] Calculate the floating-point single-difference carrier phase ambiguity of reference satellite i in Equation (1) according to the pseudorange and carrier phase observations and obtain the carrier phase single-difference ambiguity of other visible satellites j through Equation (2)

[0107]

[0108] Combine the single-difference ambiguity in Equation (2) and the single-difference carrier phase observation equation to determine the receiver clock offset between stations as shown in Equation (3):

[0109]

[0110] Determine the single-difference pseudorange and carrier-phase dual-frequency IF combined observations as shown in Equation (4):

[0111]

[0112] By taking the difference between the ionosphere-free combined double-difference pseudorange observation and the carrier-phase observation, obtain the double-difference floating ambiguity of the ionosphere-free combination:

[0113]

[0114] Use the floating single-difference carrier-phase ambiguity of reference satellite i in Equation (5) and obtain the single-difference carrier-phase ambiguity of other visible satellites j through Equation (6)

[0115]

[0116] According to the single-difference ambiguity and the single-difference carrier-phase observation equation, determine the receiver clock difference between stations as shown in Equation (7):

[0117]

[0118] In some embodiments, the receiver clock difference calculation module is further configured to:

[0119] Obtain the time difference result between stations for each visible satellite through the single-frequency solution of Equation (3) or the dual-frequency IF combined solution of Equation (7).

[0120] In some embodiments, the receiver clock difference calculation module is further configured to:

[0121] While setting the satellite elevation cut-off angle, adopt the weight determination method of W j = θ j / 90° to obtain the time transfer result as shown in Equation (8):

[0122]

[0123] where T f represents the differential single-frequency carrier-phase time-frequency transfer result, and T IF represents the differential dual-frequency IF combined carrier-phase time-frequency transfer result.

[0124] In some embodiments, the stability evaluation module is further configured, and processes the receiver clock difference through the modified Allan deviation to evaluate and analyze the frequency stability of the crystal oscillator to be measured:

[0125] It should be noted that the device described in this embodiment and the method described previously belong to the same technical concept and can achieve the same technical effects, which will not be elaborated here.

[0126] An embodiment of the present invention provides a readable storage medium, which stores one or more programs, and the one or more programs can be executed by one or more processors to implement the methods described in the above respective embodiments.

[0127] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more of their solutions) can be used in combination with each other. For example, those of ordinary skill in the art can use other embodiments when reading the above description. Additionally, in the above specific embodiments, various features can be grouped together to simplify the present invention. This should not be construed as an intention that the features of an invention not claimed are necessary for any claim. On the contrary, the subject matter of the present invention can be less than all the features of a particular embodiment of the invention. Thus, the following claims are hereby incorporated into the specific embodiments as examples or embodiments, where each claim independently serves as a separate embodiment, and considering these embodiments, they can be combined with each other in various combinations or permutations. The scope of the present invention should be determined with reference to the appended claims and the full scope of the equivalents to which these claims are entitled.

Claims

1. A method for evaluating clock stability, characterized in that, the method includes: Using the oscillator under test as the internal clock of the first receiver, and obtaining observation data by capturing and tracking satellite signals, where the observation data reflects the clock characteristics of the oscillator under test; Connecting an external time-frequency reference source to the second receiver as the local clock to obtain observation data; Performing DPT time transfer calculation on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain receiver clock offsets, where the receiver clock offsets reflect the difference between the time represented by the oscillator under test and the time-frequency reference source; Processing the receiver clock offsets through deviations to evaluate and analyze the frequency stability of the oscillator under test; Performing DPT time transfer calculation on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain receiver clock offsets, including: The single-difference pseudorange and carrier phase observations for any frequency f are as shown in Equation (1): where represents the receiver clock difference between the time-frequency reference station and the user station, c is the speed of light, is the single-difference pseudorange observation between stations, is the single-difference residual value of tropospheric delay, is the single-difference residual value of ionospheric delay, is the measurement noise of the single-difference pseudorange observation between stations, is the single-difference carrier phase observation between stations, λ f is the wavelength at frequency f, is the floating single-difference carrier phase ambiguity of reference satellite i, is the measurement noise of the single-difference carrier phase observation between stations; Calculate the floating single-difference carrier phase ambiguity of the reference satellite i in Equation (1) based on pseudorange and carrier phase observations And obtain the single-difference carrier phase ambiguity of other visible satellites j through Equation (2) wherein is the double-difference carrier phase integer ambiguity of satellite j relative to reference satellite i, which is directly obtained through the double-difference observation of the existing RTK technology; Combined with the single-difference ambiguity in Equation (2) and the single-difference carrier-phase observation equation, the receiver clock offset between stations is determined as shown in Equation (3): Among them, is the single-difference geometric distance between stations from the satellite to the receiver; Determining the dual-frequency IF combined observations of the single-difference pseudorange and carrier phase as shown in Equation (4): wherein, is the inter-station single-difference ionosphere-free combination pseudorange observation value, is the inter-station single-difference ionosphere-free combination carrier phase observation value, is the inter-station single-difference ionosphere-free combination geometric distance from the satellite to the receiver, is the ionosphere-free combination receiver clock difference between the time-frequency reference station and the user station, is the residual value of the tropospheric delay single-difference ionosphere-free combination, is the measurement noise of the inter-station single-difference pseudorange observation value in the ionosphere-free combination, λ IF is the ionosphere-free combination wavelength, is the floating single-difference ionosphere-free combination carrier phase ambiguity of the reference satellite i, is the measurement noise of the inter-station single-difference carrier phase observation value in the ionosphere-free combination, c = λ f ·f; Obtaining the double-difference floating-point ambiguity of the ionosphere-free combination by taking the difference between the ionosphere-free combination double-difference pseudorange observation and the carrier phase observation; Use the floating single-difference carrier phase ambiguity of reference satellite i in Equation (5) And obtain the single-difference carrier phase ambiguity of other visible satellites j through Equation (6) According to the single-difference ambiguity and the single-difference carrier-phase observation equation, the receiver clock difference between stations is determined as shown in Equation (7):

2. The method according to claim 1, characterized in that, both the first receiver and the second receiver are GNSS receivers.

3. The method according to claim 1, characterized in that, the time-frequency reference source is UTC(k) or a high-precision atomic clock.

4. The method according to claim 1, characterized in that, Performing DPT time transfer calculation on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain receiver clock offsets, further including: Obtaining the inter-station time difference results for each visible satellite through single-frequency calculation using Equation (3) or dual-frequency IF combined calculation using Equation (7).

5. The method according to claim 4, characterized in that, Performing DPT time transfer calculation on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain receiver clock offsets, further including: While setting the satellite elevation cut-off angle, the weight determination method of W j = θ j / 90° is adopted to obtain the time transfer result as shown in Equation (8): Where T f It represents the time-frequency transfer result of differential single-frequency carrier phase, T IF It represents the time-frequency transfer result of differential dual-frequency IF combined carrier phase, W j W j =θ j / 90° weighting method, θ j Indicates the satellite cutoff elevation angle.

6. The method according to claim 1, characterized in that, Processing the receiver clock offsets based on the modified Allan deviation to evaluate and analyze the frequency stability of the oscillator under test:

7. An apparatus for evaluating clock stability, characterized in that, the apparatus includes: A first observation module configured to use the oscillator under test as the internal clock of the first receiver and obtain observation data by capturing and tracking satellite signals, where the observation data reflects the clock characteristics of the oscillator under test; A second observation module configured to connect an external time-frequency reference source to the second receiver as the local clock to obtain observation data; A receiver clock offset calculation module configured to perform DPT time transfer calculation on the observation data and broadcast ephemeris of the first receiver and the second receiver to obtain receiver clock offsets, where the receiver clock offsets reflect the difference between the time represented by the oscillator under test and the time-frequency reference source; A stability evaluation module configured to process the receiver clock offsets through deviations to evaluate and analyze the frequency stability of the oscillator under test; The receiver clock offset calculation module is further configured to: The single-difference pseudorange and carrier phase observations for any frequency f are as shown in Equation (1): where represents the receiver clock difference between the time-frequency reference station and the user station, c is the speed of light, is the single-difference pseudorange observation between stations, is the single-difference residual value of tropospheric delay, is the single-difference residual value of ionospheric delay, is the measurement noise of the single-difference pseudorange observation between stations, is the single-difference carrier phase observation between stations, λ f is the wavelength of frequency f, is the floating single-difference carrier phase ambiguity of reference satellite i, is the measurement noise of the single-difference carrier phase observation between stations; Calculate the floating single-difference carrier phase ambiguity of the reference satellite i in Equation (1) based on pseudorange and carrier phase observations And obtain the carrier phase single-difference ambiguity of other visible satellites j through Equation (2) Among them is the double-difference carrier phase integer ambiguity of satellite j relative to reference satellite i, which is directly obtained through the double-difference observation of existing RTK technology; Combined with the single-difference ambiguity in Equation (2) and the single-difference carrier phase observation equation, the receiver clock offset between stations is determined as shown in Equation (3): wherein, is the single-difference geometric distance between stations from the satellite to the receiver; The single-difference pseudorange and the carrier-phase dual-frequency IF combination observations are determined as shown in Equation (4): Among them, is the inter-station single-difference pseudorange ionosphere-free combination observation value, is the inter-station single-difference carrier phase ionosphere-free combination observation value, is the inter-station single-difference ionosphere-free combination geometric distance from the satellite to the receiver, is the ionosphere-free combination receiver clock difference between the time-frequency reference station and the user station, is the residual value of the tropospheric delay single-difference ionosphere-free combination, is the measurement noise of the inter-station single-difference pseudorange observation value ionosphere-free combination, λ IF is the ionosphere-free combination wavelength, is the floating single-difference ionosphere-free combination carrier phase ambiguity of the reference satellite i, is the measurement noise of the inter-station single-difference carrier phase observation value ionosphere-free combination, c = λ f ·f; By taking the difference between the ionosphere-free combined double-difference pseudorange observations and the carrier-phase observations, the double-difference floating ambiguity of the ionosphere-free combination is obtained: Use the floating single-difference carrier phase ambiguity of reference satellite i in Equation (5) And obtain the single-difference carrier phase ambiguity of other visible satellites j through Equation (6) According to the single-difference ambiguity and the single-difference carrier-phase observation equation, the receiver clock difference between stations is determined as shown in Equation (7):

8. A readable storage medium, characterized in that, the readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the method according to any one of claims 1 to 6.

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