High-precision phase comparison measurement system and method in large dynamic range

Abstract

The invention relates to a high-precision phase comparison measurement system and method in a large dynamic range. The system comprises a frequency coarse estimation module, a frequency fine measurement module and a phase measurement comparison module. Performing automatic closed-loop measurement on the frequency of the to-be-measured digital signal in a mode of combining FFT frequency measurement and I-Q demodulation phase measurement to obtain a rough frequency estimation value of the to-be-measured signal; automatically tracking and locking the frequency of the to-be-measured signal according to the rough frequency estimation value of the to-be-measured signal and the to-be-measured digital signal by adopting a phase-locked loop technology to obtain a precise frequency value of the to-be-measured signal; and calculating the phase difference between the to-be-measured signal and the reference signal. The phase locking technology is adopted, high-precision measurement of the frequency of the signal to be measured is achieved in the mode of combining frequency coarse estimation and frequency precision measurement, and the problem of phase drift caused by NCO frequency offset in the phase measurement process of an I-Q demodulation method is solved.

Description

Technical Field

[0001] This application relates to the fields of time and frequency, metrology, and calibration, and specifically to a high-precision phase comparison measurement system and method over a large dynamic range. Background Technology

[0002] High-precision time and frequency measurements have been widely applied in various fields, including space technology, national metrology, and national infrastructure construction. High-precision phase comparison measurement technology is fundamental to time and frequency measurement, preservation, and transmission, and its measurement level directly affects the application capabilities of time and frequency. Currently, methods suitable for frequency signal phase comparison measurements include: frequency difference multiplication method, beat method, double mixing time difference method, function correlation method, spectral analysis method (FFT phase measurement and full-phase FFT phase measurement), and IQ demodulation method. These methods, without considering factors such as low cost, low power consumption, and small size during engineering, can all perform phase comparison measurements between a test signal and a reference signal with relatively fixed frequencies; however, these methods lack the ability to automatically track and measure the phase between the test signal and the reference signal when the frequency range of the test signal changes. Summary of the Invention

[0003] To overcome at least one deficiency in the prior art, this application provides a high-precision phase comparison measurement system and method with a large dynamic range.

[0004] In the first aspect, a high-precision phase comparison measurement system with a large dynamic range is provided, including: a frequency coarse estimation module, a frequency fine measurement module and a phase measurement and comparison module; The signal under test is converted from analog to digital by an ADC to obtain the digitized signal under test; the reference signal is converted from analog to digital by an ADC to obtain the reference digitized signal. The coarse frequency estimation module for the input frequency of the digital signal under test uses a combination of FFT frequency measurement and IQ demodulation phase measurement to achieve automatic closed-loop frequency measurement and obtain a coarse estimate of the frequency of the signal under test. The rough estimate of the frequency of the signal under test and the digital signal under test are input into the fine frequency measurement module. The phase-locked loop technology is used to realize the automatic tracking and locking of the frequency of the signal under test, so as to obtain the precise frequency value of the signal under test. The digital signal to be tested, the reference digital signal, the precise frequency value of the signal to be tested, and the precise frequency value of the reference signal are input into the phase measurement and comparison module to obtain the phase difference between the signal to be tested and the reference signal.

[0005] In one embodiment, the frequency coarse estimation module includes an FFT module, a first NCO, a first IQ demodulation module, and a phase-frequency conversion module; The FFT module performs an FFT operation on the digitized signal under test to obtain a frequency estimate. The frequency estimate is used as the initial frequency value of the first NCO, which generates two orthogonal signals. The two orthogonal signals and the digitized signal under test are input to the first IQ demodulation module to obtain a first phase. The first phase is input to the phase-frequency conversion module to obtain a first frequency correction value. The frequency value of the first NCO is continuously corrected using the first frequency correction value to obtain a rough estimate of the frequency of the signal under test.

[0006] In one embodiment, the frequency fine measurement module includes: a second NCO, a second IQ demodulation module, and a loop filter; The rough estimate of the frequency of the signal under test is used as the initial input value of the frequency of the second NCO. The second NCO generates two quadrature signals. The two quadrature signals and the digitized signal under test are input to the second IQ demodulation module to obtain the second phase. The second phase is input to the loop filter to generate the frequency adjustment amount. The frequency value of the second NCO is continuously corrected using the frequency adjustment amount to obtain the precise frequency value of the signal under test.

[0007] In one embodiment, the phase measurement and comparison module includes: a third NCO, a fourth NCO, a third IQ demodulation module, and a fourth IQ demodulation module; The precise frequency value of the signal under test is input to the third NCO to generate two orthogonal signals; the two orthogonal signals and the digitized signal under test are input to the third IQ demodulation module to obtain the third phase; The precise frequency value of the reference signal is input to the fourth NCO to generate two quadrature signals; the two quadrature signals and the reference digitized signal are input to the fourth IQ demodulation module to obtain the fourth phase; The ratio of the precision frequency value of the signal under test to the precision frequency value of the reference signal is multiplied by the fourth phase to obtain the adjusted fourth phase; The phase difference between the signal under test and the reference signal is obtained based on the third phase and the adjusted fourth phase.

[0008] In one embodiment, the precision frequency value of the reference signal is a set value.

[0009] In one embodiment, the precise frequency value of the reference signal is obtained by means of: The reference digitized signal passes through the frequency coarse estimation module and the frequency fine measurement module in sequence to obtain the precise frequency value of the reference signal.

[0010] Secondly, a high-precision phase comparison measurement method with a large dynamic range is provided, based on the aforementioned high-precision phase comparison measurement system with a large dynamic range, including: The signal to be tested is converted from analog to digital to obtain the digital signal to be tested; The reference signal is converted from analog to digital to obtain a reference digitized signal; The frequency of the digital signal under test is automatically closed-loop measured by combining FFT frequency measurement and IQ demodulation phase measurement, so as to obtain a rough estimate of the frequency of the signal under test. A phase-locked loop (PLL) technique is used to automatically track and lock the frequency of the signal under test, based on a rough estimate of the frequency of the signal under test and the digital signal under test, to obtain a precise frequency value of the signal under test. The phase difference between the digitized signal under test and the reference digitized signal is calculated based on the digitized signal under test, the reference digitized signal, the precise frequency value of the digitized signal under test, and the precise frequency value of the reference signal.

[0011] Compared with the prior art, this application has the following beneficial effects: 1. This application adopts phase-locked loop technology. Based on considerations such as low complexity, low cost, and full digitalization in the engineering process, it adopts a combination of coarse frequency estimation and precise frequency measurement to achieve high-precision measurement of the frequency of the signal under test, thereby avoiding the phase drift problem caused by NCO frequency offset in the phase measurement process of IQ demodulation method.

[0012] 2. This application can be implemented entirely digitally, and is feasible for productization and high integration. It is also universal and can be widely used in high-precision phase comparison systems, frequency stability measurement systems, phase noise measurement systems, digital phase-locked loop control systems, high-precision time and frequency systems, as well as high-precision clock source control and performance evaluation. This method has broad market application prospects and practical value. Attached Figure Description

[0013] This application can be better understood by referring to the description given below in conjunction with the accompanying drawings, which, together with the detailed description below, are incorporated in and form part of this specification. In the drawings: Figure 1 A schematic diagram of a high-precision phase comparison measurement system with a large dynamic range is shown. Figure 2 A schematic diagram of the frequency coarse estimation module is shown; Figure 3 A schematic diagram of the frequency fine measurement module is shown; Figure 4 A schematic diagram of the phase measurement and comparison module is shown. Detailed Implementation

[0014] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of the actual embodiments are described in the specification. However, it should be understood that many embodiment-specific decisions can be made in the development of any such actual embodiment to achieve the developer’s specific objectives, and these decisions may vary as the embodiments differ.

[0015] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the device structure closely related to the solution according to this application is shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0016] It should be understood that this application is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, embodiments may be combined with each other, features may be substituted or borrowed between different embodiments, and one or more features may be omitted in one embodiment, where feasible.

[0017] This application provides a high-precision phase comparison measurement system with a large dynamic range. Figure 1 A schematic diagram of a high-precision phase comparison measurement system with a large dynamic range is shown. (See attached diagram) Figure 1 , Figure 1 Solid lines represent signals that must participate in signal processing during the process, while dashed lines represent signals that can participate in signal processing depending on the actual situation. The system includes: a coarse frequency estimation module, a fine frequency measurement module, and a phase measurement and comparison module. The functions of each module are described in detail below.

[0018] The signal under test is converted from analog to digital by an ADC (analog-to-digital converter) to obtain the digitized signal under test. The reference signal is converted from analog to digital by an ADC to obtain a reference digitized signal. ; Digital signal under test The input frequency coarse estimation module uses a combination of FFT frequency measurement and IQ demodulation phase measurement to achieve automatic closed-loop frequency measurement and obtain a coarse estimate of the frequency of the signal under test. Rough estimate of the frequency of the signal under test and the digitized signal under test The input frequency fine measurement module uses phase-locked loop technology to automatically track and lock the frequency of the signal under test, thereby obtaining the precise frequency value of the signal under test. Digital signal under test Reference digital signal The precise frequency values ​​of the signal under test and the reference signal are input into the phase measurement and comparison module to obtain the phase difference between the signal under test and the reference signal.

[0019] In one embodiment, Figure 2 A schematic diagram of the frequency coarse estimation module is shown; see [link / reference]. Figure 2 The frequency coarse estimation module includes an FFT module, a first NCO (digitally controlled oscillator), a first IQ demodulation module, and a phase-frequency conversion module. The FFT module is used to test the digital signal. Perform FFT operation to obtain frequency estimates Frequency estimates As the initial frequency value of the first NCO, the first NCO generates two orthogonal signals; the two orthogonal signals and the digitized signal to be measured The input is fed into the first IQ demodulation module to obtain the first phase; the first phase is then fed into the phase-frequency conversion module to obtain the first frequency correction value. ; Using the first frequency correction value Continuously adjust the frequency value of the first NCO This yields a rough estimate of the frequency of the signal under test. and The values ​​are added together to obtain the new frequency value of the first NCO, which is a rough estimate of the frequency of the signal under test. In this process, the number of FFT operation points, the number of bits in the phase accumulator of the first NCO, the filter order, and the sampling rate are all related to hardware resources and running speed.

[0020] In one embodiment, Figure 3 A schematic diagram of the frequency fine measurement module is shown; see [link / reference]. Figure 3 The frequency fine measurement module includes: a second NCO, a second IQ demodulation module, and a loop filter; The rough estimate of the frequency of the signal under test is used as the initial frequency input value of the second NCO. The second NCO generates two orthogonal signals; these two orthogonal signals are then compared with the digitized signal under test. The input is fed into the second IQ demodulation module to obtain the second phase; the second phase is then input into the loop filter to generate the frequency adjustment. ; Utilizing frequency adjustment amount Continuously adjust the frequency value of the second NCO This yields a new frequency value for the second NCO. The frequency value of the second NCO is the precise frequency value of the signal under test. Once the loop is locked, the new frequency value of the second NCO is the final precise frequency value of the signal under test. Here, the frequency adjustment amount... Frequency value of the second NCO Add them together to get a new frequency value.

[0021] Here, the number of bits in the phase accumulator of the second NCO, the filter order in the IQ demodulation module, and the phase accuracy are all related to hardware resources and operating speed.

[0022] Figure 4 A schematic diagram of the phase measurement and comparison module is shown. (See attached diagram) Figure 4 The phase measurement and comparison module includes: a third NCO, a fourth NCO, a third IQ demodulation module, and a fourth IQ demodulation module; The precise frequency value of the signal under test is input to the third NCO, generating two orthogonal signals; the two orthogonal signals and the digitized signal under test are then fed into the NCO. The input is fed into the third IQ demodulation module to obtain the third phase; The precise frequency value of the reference signal is input to the fourth NCO, generating two quadrature signals; these two quadrature signals, along with the reference digitized signal, are then fed into the NCO. The input is fed into the fourth IQ demodulation module to obtain the fourth phase; The ratio of the precision frequency value of the signal under test to the precision frequency value of the reference signal is multiplied by the fourth phase to obtain the adjusted fourth phase; The phase difference between the measured signal and the reference signal is obtained based on the third phase and the adjusted fourth phase. Here, the difference between the third phase and the adjusted fourth phase is calculated to obtain the phase difference between the measured signal and the reference signal.

[0023] It should be noted that the coarse frequency estimation module continuously outputs a rough estimate of the frequency of the signal under test, while the fine frequency measurement module continuously outputs a precise frequency value of the signal under test, and the phase measurement and comparison module continuously calculates the phase difference. Once the loop is locked, the calculated phase difference becomes the final precise phase difference.

[0024] In one embodiment, the precise frequency value of the reference signal can be a set value.

[0025] In other embodiments, the precise frequency value of the reference signal can also be obtained in the following ways: The reference digitized signal passes sequentially through a coarse frequency estimation module and a fine frequency measurement module to obtain the precise frequency value of the reference signal, such as... Figure 1 As shown by the dashed line.

[0026] This application also provides a high-precision phase comparison measurement method with a large dynamic range, and a high-precision phase comparison measurement system with a large dynamic range based on the above embodiments, including: The signal to be tested is converted from analog to digital to obtain the digital signal to be tested; The reference signal is converted from analog to digital to obtain a reference digitized signal; The frequency of the digital signal under test is automatically closed-loop measured by combining FFT frequency measurement and IQ demodulation phase measurement, so as to obtain a rough estimate of the frequency of the signal under test. A phase-locked loop (PLL) technique is used to automatically track and lock the frequency of the signal under test, based on a rough estimate of the frequency of the signal under test and the digital signal under test, to obtain a precise frequency value of the signal under test. The phase difference between the digitized signal under test and the reference digitized signal is calculated based on the digitized signal under test, the reference digitized signal, the precise frequency value of the digitized signal under test, and the precise frequency value of the reference signal.

[0027] The high-precision phase comparison measurement method in this embodiment has the same inventive concept as the high-precision phase comparison measurement system in the large dynamic range described above. Therefore, the specific implementation of this method can be found in the embodiment section of the optimization method of the high-precision phase comparison measurement system in the large dynamic range described above, and its technical effect corresponds to the technical effect of the above method, so it will not be repeated here.

[0028] In summary, this application has the following technical effects: 1. This application adopts phase-locked loop technology. Based on considerations such as low complexity, low cost, and full digitalization in the engineering process, it adopts a combination of coarse frequency estimation and precise frequency measurement to achieve high-precision measurement of the frequency of the signal under test, thereby avoiding the phase drift problem caused by NCO frequency offset in the phase measurement process of IQ demodulation method.

[0029] 2. This application can be implemented entirely digitally, and is feasible for productization and high integration. It is also universal and can be widely used in high-precision phase comparison systems, frequency stability measurement systems, phase noise measurement systems, digital phase-locked loop control systems, high-precision time and frequency systems, as well as high-precision clock source control and performance evaluation. This method has broad market application prospects and practical value.

[0030] The above descriptions are merely various embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A high-precision phase comparison measurement system with a large dynamic range, characterized in that, include: The module includes a coarse frequency estimation module, a fine frequency measurement module, and a phase measurement and comparison module. The signal under test is converted from analog to digital by an ADC to obtain the digitized signal under test; the reference signal is converted from analog to digital by an ADC to obtain the reference digitized signal. The digital signal to be tested is input into the frequency coarse estimation module, and the frequency is automatically closed-loop measured by combining FFT frequency measurement and IQ demodulation phase measurement to obtain a coarse estimate of the frequency of the signal to be tested. The rough estimate of the frequency of the signal under test and the digital signal under test are input into the fine frequency measurement module. The phase-locked loop technology is used to realize the automatic tracking and locking of the frequency of the signal under test, so as to obtain the precise frequency value of the signal under test. The digital signal to be tested, the reference digital signal, the precise frequency value of the signal to be tested, and the precise frequency value of the reference signal are input into the phase measurement and comparison module to obtain the phase difference between the signal to be tested and the reference signal.

2. The system as described in claim 1, characterized in that, The frequency coarse estimation module includes an FFT module, a first NCO, a first IQ demodulation module, and a phase-frequency conversion module; The FFT module performs an FFT operation on the digitized signal under test to obtain a frequency estimate. The frequency estimate is used as the initial frequency value of the first NCO, which generates two orthogonal signals. The two orthogonal signals and the digitized signal under test are input to the first IQ demodulation module to obtain a first phase. The first phase is input to the phase-frequency conversion module to obtain a first frequency correction value. The frequency value of the first NCO is continuously corrected using the first frequency correction value to obtain a rough estimate of the frequency of the signal under test.

3. The system as described in claim 1, characterized in that, The frequency fine measurement module includes: a second NCO, a second IQ demodulation module, and a loop filter; The rough frequency estimate of the signal under test is used as the initial frequency input value of the second NCO. The second NCO generates two quadrature signals. The two quadrature signals and the digitized signal under test are input to the second IQ demodulation module to obtain the second phase. The second phase is input to the loop filter to generate a frequency adjustment amount. The frequency value of the second NCO is continuously corrected using the frequency adjustment amount to obtain the precise frequency value of the signal under test.

4. The system as described in claim 1, characterized in that, The phase measurement and comparison module includes: a third NCO, a fourth NCO, a third IQ demodulation module, and a fourth IQ demodulation module; The precise frequency value of the signal under test is input to the third NCO to generate two quadrature signals; the two quadrature signals and the digitized signal under test are input to the third IQ demodulation module to obtain the third phase; The precise frequency value of the reference signal is input to the fourth NCO to generate two quadrature signals; the two quadrature signals and the reference digitized signal are input to the fourth IQ demodulation module to obtain the fourth phase; The ratio of the precision frequency value of the signal under test to the precision frequency value of the reference signal is multiplied by the fourth phase to obtain the adjusted fourth phase. The phase difference between the signal under test and the reference signal is obtained based on the third phase and the adjusted fourth phase.

5. The system as described in claim 1, characterized in that, The precision frequency value of the reference signal is a set value.

6. The system as described in claim 1, characterized in that, The methods for obtaining the precise frequency value of the reference signal include: The reference digitized signal is sequentially passed through the frequency coarse estimation module and the frequency fine measurement module to obtain the precise frequency value of the reference signal.

7. A high-precision phase comparison measurement method over a large dynamic range, characterized in that, The high-precision phase comparison measurement system with a large dynamic range according to any one of claims 1-6 includes: The signal to be tested is converted from analog to digital to obtain the digital signal to be tested; The reference signal is converted from analog to digital to obtain a reference digitized signal; The frequency of the digital signal under test is automatically closed-loop measured by combining FFT frequency measurement and IQ demodulation phase measurement, so as to obtain a rough estimate of the frequency of the signal under test. A phase-locked loop (PLL) technique is used to automatically track and lock the frequency of the signal under test to obtain a precise frequency value of the signal under test, based on a rough estimate of the frequency of the signal under test and the digital signal under test. The phase difference between the signal under test and the reference signal is calculated based on the digital signal under test, the reference digital signal, the precision frequency value of the signal under test, and the precision frequency value of the reference signal.

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