A method and apparatus for generating a low-depth phase modulation signal at a low frequency band

Abstract

The application belongs to the field of signal detection and precision measurement, and specifically discloses a method and device for generating a low-depth phase modulation signal in a low frequency band. The device is as follows: three channels of a multi-channel function generator respectively output sine wave signals with frequencies of f1, f2 and f3; a first power divider divides the sine wave signal with the frequency of f1 into two paths, one of which is a reference signal; the other path inputs two-channel phase meters; a second power divider synthesizes three input sine wave signals with frequencies of f1, f2 and f3 to generate a to-be-tested signal, and the frequency spectrum of the to-be-tested signal presents a phase modulation characteristic of a carrier plus a symmetrical double sideband; the two-channel phase meters are used for phase demodulation of the reference signal and the to-be-tested signal to obtain two-phase data; and a data processing unit is used for differential subtraction of the two-phase data, calculation of the amplitude of the sine wave signal with the frequency of f1, comparison with a theoretical phase modulation depth, and realization of phase meter calibration. The application has the advantage of generating a lower-depth phase modulation signal in a low frequency band.

Description

Technical Field

[0001] This application belongs to the field of signal detection and precision measurement, and more specifically, relates to a method and apparatus for generating low-depth phase modulation signals in the low-frequency band. Background Technology

[0002] In precision measurement devices such as space gravitational wave detectors, extremely high-precision phase measurements of signals are required, with accuracy reaching the microradian level or even better in the low-frequency band. As a key component for extracting phase information, the phase meter's ability to detect minute phase changes within its actual operating frequency band must be rigorously calibrated and verified to ensure the accuracy and reliability of the measurement results. Therefore, it is necessary to generate a phase modulation signal with a low phase modulation depth and a modulation frequency in the millihertz low-frequency band as a standard excitation source to evaluate or calibrate the phase extraction performance of the phase meter in the ultra-low frequency band.

[0003] However, generating phase-modulated signals in the millihertz band at levels below microradians presents numerous challenges. Traditional methods utilize the internal or external analog phase modulation function of the signal source to inject a low-frequency modulation signal into the signal source to modulate the carrier phase. The minimum phase modulation depth of existing function generators is typically on the order of tens of microradians, which is insufficient to meet the calibration and testing requirements of high-precision phase meters.

[0004] In summary, the existing technology lacks a method to stably generate low-depth phase modulation signals in the low-frequency band, which makes it difficult to provide a reliable ultra-low frequency micro-phase calibration means for the effective calibration of the detection capability of high-precision phase meters. This is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a method and apparatus for generating low-depth phase modulation signals in the low-frequency band. This aims to solve the problem that the minimum phase modulation depth of existing function generators is typically on the order of tens of microradians when injecting low-frequency modulation signals into a signal source to perform phase modulation on a carrier, which is difficult to meet the calibration and testing requirements of high-precision phase meters.

[0006] The first aspect of this application relates to an apparatus for generating low-depth phase modulation signals in the low-frequency band, comprising: a multi-channel function generator, a first power divider, a second power divider, a two-channel phase meter, and a data processing unit. The multi-channel function generator has three independent output channels. The first channel is used to output a frequency of The sine wave signal; the second and third channels output frequencies of... and The sinusoidal signal has the same amplitude in the second and third channels, but their phases differ. radians; where, For carrier frequency; The modulation frequency; The first power divider is a radio frequency power divider with one input and two outputs, used to divide the frequency generated by the first channel into two channels. The sinusoidal signal is divided into two paths: one path is input to a two-channel phase meter as a reference signal, and the other path is input to a second power divider for the synthesis of the signal to be measured. The second power divider is a three-input, one-output RF power divider, used to divide the three input frequencies as follows: , and The sinusoidal signal is synthesized to generate a test signal. The spectrum of the test signal exhibits phase modulation characteristics of carrier plus symmetrical double sideband. The two-channel phase meter is used to demodulate the phase of the reference signal and the signal under test respectively, and to acquire two phase data. The data processing unit performs differential subtraction on the two phase data streams to obtain differential phase data, and calculates the frequency as follows: The amplitude of the sinusoidal signal is compared with the theoretical phase modulation depth to calibrate the phase meter.

[0007] In some implementations, the time-domain expression of the phase modulation signal of the signal under test is... for: ; in, Carrier amplitude; For carrier frequency; Modulation depth; The modulation frequency; The phase modulation depth of the signal under test; For time.

[0008] In some implementations, the frequency of the first channel generation is The amplitude of the sinusoidal signal is The amplitudes of the sinusoidal signals output from the second and third channels are The phase modulation depth of the signal under test is By setting and The ratio of these values ​​ensures that the phase modulation depth is within 0.1 radians.

[0009] In some implementations, the modulation frequency To allow arbitrary setting within the low-frequency band according to phase meter calibration requirements, where the low-frequency range is on the order of mHz; carrier frequency... It is on the order of MHz.

[0010] In some implementations, the three output channels in a multichannel function generator share the same internal clock reference.

[0011] A second aspect of this application relates to a method for generating a low-depth phase-modulated signal in a low-frequency band, comprising the following steps: Step S101: The first channel of the multi-channel function generator generates a frequency of... A sinusoidal signal; the second and third channels of a multi-channel function generator respectively generate a phase difference of... radians, frequency and A sinusoidal signal; Step S102: The frequency generated by the first channel is... The sinusoidal signal is split into two paths by the first power divider. The first output terminal outputs a reference signal, and the signal output from the second output terminal has the same frequency as the signals generated by the second and third channels, respectively. and The sinusoidal signal is synthesized into a test signal by the second power divider; the spectrum of the test signal exhibits phase modulation characteristics of carrier plus symmetrical double sideband; Step S103: Send the reference signal and the signal under test to the first and second input terminals of the two-channel phase meter respectively for phase demodulation to obtain two channels of phase data; Step S104: Perform differential subtraction on the two phase data streams to obtain differential phase data, and calculate the frequency from the differential phase data. The amplitude of the sinusoidal signal is compared with the theoretical phase modulation depth to calibrate the phase meter.

[0012] In some implementations, the time-domain expression of the phase modulation signal of the signal under test is... for: ; in, Carrier amplitude; For carrier frequency; Modulation depth; The modulation frequency; The phase modulation depth of the signal under test; For time.

[0013] In some implementations, the frequency of the first channel generation is The amplitude of the sinusoidal signal is The amplitudes of the sinusoidal signals output from the second and third channels are The phase modulation depth of the signal under test is By setting and The ratio of these values ​​ensures that the phase modulation depth is within 0.1 radians.

[0014] In some implementations, the modulation frequency To allow arbitrary setting within the low-frequency band according to phase meter calibration requirements, where the low-frequency range is on the order of mHz; carrier frequency... It is on the order of MHz.

[0015] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: This application provides a method for generating low-depth phase-modulated signals in the low-frequency band. A carrier signal and upper and lower sideband signals are generated separately through different channels of a multi-channel function generator. These three signals are then combined by a power divider to form an equivalent phase-modulated signal. Furthermore, the sideband amplitude of the combined signal satisfies a defined linear relationship with the phase modulation depth, allowing this signal to serve as a standard excitation source with a known phase modulation depth. Compared to standard phase modulation, this application's method uses the linear superposition of multiple sine waves to generate the combined signal and, by setting a small amplitude for the sideband signal, achieves the advantage of generating even lower-depth phase-modulated signals in the low-frequency band.

[0016] The signal to be measured and the reference signal are respectively sent to two-channel phase meters for demodulation and differential subtraction. The carrier phase noise is canceled by the common mode, and the phase modulation signal is retained in the differential data. The correctness of the signal is verified by amplitude comparison. This provides a reliable ultra-low frequency micro phase calibration method for high-precision phase meters in precision measurement fields such as gravitational wave detection. Attached Figure Description

[0017] Figure 1 This is a diagram showing the difference in amplitude of the time-domain waveforms of the phase signals after standard phase modulation and equivalent phase modulation demodulation, as provided in the embodiments of this application.

[0018] Figure 2 This is a flowchart of a method for generating a low-depth phase modulation signal in the low-frequency band, provided in an embodiment of this application.

[0019] Figure 3 This is a schematic diagram of the spectrum structure of a low-depth phase modulation signal provided in an embodiment of this application.

[0020] Figure 4 This is a structural diagram of a device for generating low-depth phase modulation signals in the low-frequency band, provided in an embodiment of this application.

[0021] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 10 is a multi-channel function generator; 1-20 are the first power divider; 2-20 are the second power divider; 30 is a two-channel phase meter; 40 is a data processing unit. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0023] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In this application, the symbol " / " indicates that the related objects are in an "or" relationship, for example, A / B means A or B.

[0024] In this application, the terms “first” and “second” are used to distinguish different objects, rather than to describe a specific order of objects.

[0025] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0026] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more.

[0027] The embodiments of this application are described below with reference to the accompanying drawings.

[0028] To facilitate understanding of the similarities and differences between the technical solution of this application and standard phase modulation, a brief analysis is provided below from the perspective of signal model.

[0029] The time-domain expression of a standard phase-modulated signal is: ; in, Carrier amplitude; For carrier frequency; Modulation depth; The modulation frequency is [value]. After the signal is demodulated by the phase meter, the expression for the output phase signal is: ; This application generates carrier and double-sideband signals separately using a multi-channel function generator. The time-domain expression of the synthesized equivalent phase-modulated signal is as follows: ; After the signal is demodulated by the phase meter, the expression of the output phase signal is: ; The amplitude value of the demodulated phase signal time-domain waveform can reflect the modulation depth. The magnitude of the phase signal amplitude obtained from standard phase modulation and demodulation is relatively small when the modulation depth is low, and the difference between the amplitude of the phase signal obtained from equivalent phase modulation and demodulation is small. Figure 1 As shown; when the modulation depth When the modulation depth is 0.1 rad, the relative error between the two is approximately on the order of three per thousand. When the modulation depth is further reduced to the order of microradians, this error becomes negligible. This indicates that the low-depth phase modulation signal generated using the technical solution of this application can replace the standard phase modulation signal.

[0030] Figure 2 This application provides a method for generating low-depth phase-modulated signals in the low-frequency band, specifically including the following steps: Step S101: The first channel of the multi-channel function generator generates a frequency of... The second and third channels generate sinusoidal wave signals with frequencies of ; and The two sinusoidal signals have a phase difference of 0. radians; where, For carrier frequency; This is the modulation frequency.

[0031] In one example, the multi-channel function generator is a multi-channel arbitrary waveform generator or function generator with at least three independent output channels; the first channel output frequency is... The sine wave signal has an amplitude of The second and third channels output frequencies of respectively are and The sinusoidal signal, the amplitude of both signals is set to However, the phase difference radians; modulation frequency The carrier frequency can be arbitrarily set within the low-frequency band according to calibration requirements, such as typical frequency points like 0.1mHz, 1mHz, or 10mHz; It can be set to 10MHz; the channels of the multi-channel function generator share the same internal clock reference, ensuring that the three output signals maintain strict phase coherence.

[0032] Step S102: The frequency generated by the first channel is... The sinusoidal signal is split into two paths by the first power divider 1-20. The first output is used as a reference signal, and the second output, along with the second and third channels of the signal source, generates frequencies of... and The sinusoidal signal is combined into a single signal to be tested by the second power divider 2-20, the spectrum of which includes the carrier frequency. and upper and lower sideband frequencies , equivalent to For carrier, It is a signal with a modulation frequency and a low phase modulation depth.

[0033] In one example, the first power divider 1-20 is a radio frequency power divider with one input and two outputs, used to divide the frequency generated by the first channel into two channels. The sinusoidal signal is split into two paths. The second power divider 2-20 is a radio frequency power divider with three inputs and one output. After the three sinusoidal signals are combined by the second power divider 2-20, the spectrum of the synthesized signal exhibits typical phase modulation characteristics of a carrier wave plus symmetrical double-sideband. Equivalent phase modulation depth From the sideband signal amplitude With carrier signal amplitude The ratio determines that, satisfying ; through precise settings and The ratio of the two values ​​can be used to determine the equivalent phase modulation depth. Keep it within 0.1 rad, if set ,but Its spectrum diagram is as follows Figure 3 As shown.

[0034] Step S103: Send the reference signal and the signal under test to the first and second input terminals of the two-channel phase meter respectively for phase demodulation to obtain two-channel phase data.

[0035] In one example, the first input of the two-channel phase meter receives the reference signal output from the first output of the first power divider 1-20, and its second input receives the synthesized test signal output from the second power divider 2-20. The two channels of the two-channel phase meter have the same hardware architecture and signal transmission characteristics to ensure symmetrical processing of the two input signals.

[0036] Step S104: Perform differential subtraction on the two phase data streams to obtain differential phase data, and calculate the frequency from the differential phase data. The amplitude of the sinusoidal signal is compared with the theoretical phase modulation depth to calibrate the phase meter.

[0037] In one example, a two-channel phase meter demodulates the phase of the test signal and the reference signal respectively, outputting two phase data streams. Since the carrier phase noise is identical in both the test signal and the reference signal, the carrier phase noise is canceled out by common-mode noise after differential subtraction, and only the frequency is retained in the differential phase data. The phase-modulated signal is used to calculate the time-domain waveform amplitude of the demodulated phase-modulated signal and compare it with the theoretical phase modulation depth. If the measured value matches the theoretical value, it indicates that the generated equivalent phase-modulated signal is correct and reliable.

[0038] Figure 3 This is a structural diagram of a device for generating low-depth phase modulation signals in the low-frequency band, provided in an embodiment of this application. Figure 4 As shown, the device includes a multi-channel function generator 10, a first power divider 1-20, a second power divider 2-20, a two-channel phase meter 30, and a data processing unit 40. In a more specific embodiment, the multi-channel function generator 10 is a multi-channel arbitrary waveform generator with three independent output channels; the first channel outputs a frequency of 10MHz and an amplitude of... 10 The first channel outputs a sine wave signal; the second channel outputs a sine wave signal with a frequency of 10MHz + 1mHz; the third channel outputs a sine wave signal with a frequency of 10MHz~1mHz; the output amplitudes of the second and third channels... All are set to 5 Phase difference radians; where, The peak-to-peak value of the signal; The first power divider 1-20 is a radio frequency power divider with one input and two outputs. Its input terminal is connected to the first channel output terminal of the multi-channel function generator 10, and is used to divide the frequency of the function into two channels. The sinusoidal signal is output in two paths; The second power divider, 2-20, is a three-input, one-output RF power divider with an operating frequency range covering 10MHz. 1MHz; the three input terminals are respectively connected to the second output terminal of the first power divider 1-20 and the second and third channel outputs of the multi-channel function generator 10; the three signals are combined into one composite signal by the second power divider 2-20, and the spectrum of the composite signal includes a 10MHz carrier and 1 MHz sideband.

[0039] The first input terminal of the two-channel phase meter 30 is connected to the first output terminal of the first power divider 1-20 to receive a 10MHz carrier signal as a reference signal; the second input terminal is connected to the output terminal of the second power divider 2-20 to connect the synthesized signal as the signal to be measured; the two-channel phase meters demodulate the phase of the signal to be measured and the reference signal respectively, and output two channels of phase data.

[0040] The data processing unit 40 is connected to the output of the two-channel phase meter 30, receives two phase data streams, performs point-by-point differential subtraction, and the carrier phase noise is canceled out by common-mode noise, allowing the phase modulation signal to be clearly observed at 1 MHz. The amplitude of the signal is calculated in the time domain and compared with the theoretical phase modulation depth to verify the correctness and reliability of the generated signal, and to complete the calibration of the phase meter.

[0041] This embodiment generates carrier and double-sideband signals separately through different channels of a multi-channel function generator, which are then combined by a power divider to effectively generate a phase-modulated signal. This scheme does not rely on the analog phase modulation interface of the signal source; instead, it sets the equivalent phase modulation depth through precise amplitude control of multiple sinusoidal signals, achieving higher modulation depth control accuracy and stability in the millihertz band. The sideband amplitude of the synthesized signal and the equivalent phase modulation depth satisfy a defined linear relationship. It can provide a reliable standard signal source for calibrating the detection capability of high-precision phase meters in the low-frequency band.

[0042] It is understood that the various numerical designations involved in the embodiments of this application, such as "first channel", "second channel", "third channel", "first input terminal", "second input terminal", etc., are only for the convenience of description and are not intended to limit the scope of the embodiments of this application.

[0043] Furthermore, it can be understood that the method provided in the above embodiments of this application is highly suitable for scenarios requiring the generation of ultra-low frequency, minute phase modulation signals, in order to accurately calibrate the low-depth phase detection capability of the phase meter in the low-frequency band. It is particularly suitable for fields requiring extremely high phase measurement accuracy, such as gravitational wave detection, providing a reliable standard signal source for the performance verification of phase measurement devices.

[0044] In summary, this application has the following advantages compared with the prior art: This application provides a method for generating low-depth phase modulation signals in the low-frequency band. The carrier signal and upper and lower sideband signals are generated by different channels of a multi-channel function generator. The three signals are combined by a power divider and are equivalent to a phase modulation signal. The sideband amplitude of the combined signal satisfies a definite linear relationship with the phase modulation depth, so that the signal can be used as a standard excitation source with a known phase modulation depth.

[0045] Compared with standard phase modulation, the proposed solution uses multiple sinusoidal waves to linearly superimpose to generate a composite signal, and by setting a small amplitude of the sideband signal, it has the advantage of generating a lower depth phase modulation signal in the low frequency band.

[0046] The signal to be measured and the reference signal are respectively sent to two-channel phase meters for demodulation and differential subtraction. The carrier phase noise is canceled by the common mode, and the phase modulation signal is retained in the differential data. The correctness of the signal is verified by amplitude comparison. This provides a reliable ultra-low frequency micro phase calibration method for high-precision phase meters in precision measurement fields such as gravitational wave detection.

[0047] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0048] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0049] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after the connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after the connection.

[0050] The above description is merely a specific embodiment 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. An apparatus for generating low-depth phase-modulated signals in the low-frequency band, characterized in that, include: Multi-channel function generator, first power divider, second power divider, two-channel phase meter and data processing unit; The multi-channel function generator has three independent output channels. The first channel is used to output a frequency of The sine wave signal; the second and third channels output frequencies of... and The sinusoidal signals in the second and third channels have the same amplitude, but their phases differ. radians; where, For carrier frequency; The modulation frequency; The first power divider is a radio frequency power divider with one input and two outputs, used to divide the frequency generated by the first channel into two channels. The sinusoidal signal is divided into two paths: one path is input to the second power divider for synthesizing the signal under test; the other path is input to a two-channel phase meter as a reference signal. The second power divider is a three-input, one-output RF power divider, used to divide the three input frequencies as follows: , and The sinusoidal signal is synthesized to generate a test signal. The spectrum of the test signal exhibits phase modulation characteristics of carrier plus symmetrical double sideband. The two-channel phase meter is used to demodulate the phase of the reference signal and the signal under test respectively, and to acquire two phase data. The data processing unit performs differential subtraction on the two phase data streams to obtain differential phase data, and calculates the frequency. The amplitude of the sinusoidal signal is compared with the theoretical phase modulation depth to calibrate the phase meter.

2. The apparatus for generating low-depth phase modulation signals in the low-frequency band according to claim 1, characterized in that, Time-domain expression of the phase modulation signal of the signal under test for: ； in, Carrier amplitude; For carrier frequency; Modulation depth; The modulation frequency; The phase modulation depth of the signal under test; For time.

3. The apparatus for generating low-depth phase modulation signals in the low-frequency band according to claim 2, characterized in that, The frequency generated by the first channel is: The amplitude of the sinusoidal signal is The amplitudes of the sinusoidal signals output from the second and third channels are The phase modulation depth of the signal under test is By setting and The ratio of these values ​​ensures that the phase modulation depth is within 0.1 radians.

4. The apparatus for generating a low-depth phase-modulated signal in the low-frequency band according to any one of claims 1 to 3, characterized in that, Modulation frequency To allow arbitrary setting within the low-frequency band according to phase meter calibration requirements, where the low-frequency range is on the order of mHz; carrier frequency... It is on the order of MHz.

5. A method for generating a low-depth phase-modulated signal in the low-frequency band based on the apparatus for generating a low-depth phase-modulated signal in the low-frequency band according to claim 1, characterized in that, Includes the following steps: Step S101: The first channel of the multi-channel function generator generates a frequency of... A sinusoidal signal; the second and third channels of a multi-channel function generator respectively generate a phase difference of... radians, frequency and A sinusoidal signal; Step S102: The frequency generated by the first channel is... The sinusoidal signal is split into two paths by the first power divider. The first output terminal outputs a reference signal, and the signal output from the second output terminal has the same frequency as the signals generated by the second and third channels, respectively. and The sinusoidal signal is synthesized into a test signal by the second power divider; the spectrum of the test signal exhibits phase modulation characteristics of carrier plus symmetrical double sideband; Step S103: Send the reference signal and the signal under test to the first and second input terminals of the two-channel phase meter respectively for phase demodulation to obtain two channels of phase data; Step S104: Perform differential subtraction on the two phase data streams to obtain differential phase data, and calculate the frequency from the differential phase data. The amplitude of the sinusoidal signal is compared with the theoretical phase modulation depth to calibrate the phase meter.

6. The method for generating a low-depth phase-modulated signal in the low-frequency band according to claim 5, characterized in that, Time-domain expression of the phase modulation signal of the signal under test for: ； in, Carrier amplitude; For carrier frequency; Modulation depth; The modulation frequency; The phase modulation depth of the signal under test; For time.

7. The method for generating a low-depth phase-modulated signal in the low-frequency band according to claim 6, characterized in that, The frequency generated by the first channel is: The amplitude of the sinusoidal signal is The amplitudes of the sinusoidal signals output from the second and third channels are The phase modulation depth of the signal under test is By setting and The ratio of these values ​​ensures that the phase modulation depth is within 0.1 radians.

8. The method for generating a low-depth phase-modulated signal in the low-frequency band according to any one of claims 5 to 7, characterized in that, Modulation frequency To allow arbitrary setting within the low-frequency band according to phase meter calibration requirements, where the low-frequency range is on the order of mHz; carrier frequency... It is on the order of MHz.

Images