Microwave photon instantaneous frequency measurement device and method

Abstract

The invention discloses a microwave photon instantaneous frequency measurement device and method, belongs to the technical field of microwave photons, and solves the problem that the measurement of the frequency of an ultra-wideband radio frequency signal in the prior art is difficult to meet the requirements of ultra-wideband quick response and low power consumption. Comprising a laser, a modulator, an optical filter, an optical amplifier, a one-to-multiple optical beam splitter, multiple optical channels, an optical detector array and a signal acquisition module which are sequentially connected, and the optical delay differences of the multiple optical channels are sequentially increased; the advantages of ultra-wideband signal processing of the microwave photon technology are utilized, the measured radio frequency signal is modulated in the optical domain, the frequency interval of the measured radio frequency signal is positioned step by step through delay interference of multiple optical channels and threshold judgment of the output power value after interference, the frequency value within a certain precision is obtained, the requirements for signal collection and data processing are lower, and the measurement accuracy is higher. The advantages of real-time processing, electromagnetic interference resistance and the like of microwave photons are exerted, meanwhile, high-speed ultra-wideband radio-frequency signals do not need to be collected and processed, and the equipment quantity and power consumption of the system can be remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave photons and relates to a microwave photon instantaneous frequency measurement device and method. Background Art

[0002] With the continuous development of radar and other fields, the ability to transmit, receive and process ultra-wideband RF signals has been continuously improved, and its working bandwidth has been continuously expanded. The microwave frequency measurement system based on traditional microwave devices is severely limited in working bandwidth. At the same time, the microwave frequency measurement system has the problems of large equipment quantity, volume, power consumption and high cost. Microwave photonic technology is not affected by electromagnetic interference, and has obvious advantages over microwave devices in terms of volume, weight and energy consumption. In particular, its excellent signal processing capability in ultra-wideband has made it widely concerned and applied in the field of frequency measurement.

[0003] Microwave photonic technology is a cross-integration technology that transforms microwave signals into the optical domain and implements signal control and processing through optical methods. Microwave photonic systems use optical fibers to distribute, transmit and process signals, and have the advantages of large bandwidth, light weight, anti-interference, and low cost. The wireless over fiber system combines traditional wireless communication with optical communication, allowing it to have the advantages of both communication technologies, effectively solving the problem of long-distance transmission of high-frequency microwave signals. At present, the frequency measurement technology of RF signals based on microwave photonic technology is mainly based on the following four methods: frequency intensity mapping method, frequency time mapping method, sweep frequency reception method, and channelized reception method. The above methods often have the problem of complex systems, and also need to be combined with electronic equipment for sweep frequency or low-frequency acquisition processing, which makes it difficult to reduce the stability of the system and the amount of equipment and power consumption of the system. For example, the invention patent with application publication number CN113391136A discloses a microwave photon frequency measurement device and method based on fixed low-frequency detection, which adopts a suppressed carrier double-sideband modulation signal to pass through a dispersive medium and a frequency shifter with a small frequency shift, and detects the heterodyne beat frequency of the dispersive optical signal and the frequency-shifted optical signal. It only needs to detect the fixed low-frequency frequency component signal to achieve the measurement of the power attenuation transfer function generated by the high-frequency microwave signal passing through the dispersive medium. However, this method has higher requirements for the acquisition and data processing of the RF signal to be measured. Therefore, it is particularly important to propose a microwave signal frequency measurement device that can simultaneously achieve ultra-wideband fast response and low power consumption. Summary of the invention

[0004] The technical solution of the present invention is used to solve the problem that the frequency of measuring ultra-wideband radio frequency signals in the prior art is difficult to meet the requirements of ultra-wideband fast response and low power consumption.

[0005] The present invention solves the above technical problems through the following technical solutions:

[0006] A microwave photon instantaneous frequency measurement device comprises a laser, a modulator, an optical filter, an optical amplifier, a one-to-many optical beam splitter, a multi-path optical channel, an optical detector array and a signal acquisition module connected in sequence; the optical channel comprises an optical attenuator, a one-to-two optical beam splitter, an optical delay and a two-in-one optical combiner; the input end of the optical attenuator is connected to the output end of the one-to-many optical beam splitter, and the output end of the optical attenuator is connected to the input end of the one-to-two optical beam splitter; the first output end of the one-to-two optical beam splitter is connected to the first input end of the optical combiner through an optical delay to form a first optical path, the second output end of the one-to-two optical beam splitter is connected to the second input end of the optical combiner to form a second optical path, and there is an optical delay difference between the first optical path and the second optical path; the output end of the optical combiner is connected to the input end of the optical detector array; the optical delay difference of the multiple optical channels increases in sequence.

[0007] Furthermore, the laser signal output by the laser is used as an optical carrier signal, and the modulator modulates the radio frequency signal to be measured onto the optical carrier signal, and the modulated optical signal contains frequency components of two optical sidebands.

[0008] Furthermore, the modulator operates in a double-sideband modulation or carrier suppression modulation state.

[0009] Furthermore, the optical filter is an upper sideband filter or a lower sideband filter.

[0010] Furthermore, the one-to-many optical beam splitter divides the optical signal into multiple optical signals of equal power, and the optical signals are attenuated by the optical attenuator on each optical channel.

[0011] Furthermore, the one-to-two optical beam splitter divides the optical signal passing through the optical attenuator into two optical signals with completely equal power. The optical signals are transmitted with delay through the first optical path and the second optical path respectively, generating a fixed optical delay difference and optical phase difference, and then are combined into one output through the two-in-one optical combiner.

[0012] Furthermore, the optical power output by the two-in-one optical combiner is compared with the average power of the optical signal, the wavelength position interval of the corresponding optical sideband is determined according to the size of the output optical power, and then the range of the RF signal to be measured is obtained according to the correspondence between the wavelength and frequency of the optical sideband.

[0013] Furthermore, the optical delay difference of the multiple optical channels increases successively, and the delay difference of adjacent optical channels increases by a factor of 2. The larger the optical delay difference, the smaller the reflection fringe period of the interference output signal intensity in the corresponding optical channel. The optical channel with the largest optical delay difference determines the accuracy of the system frequency measurement, and locates the frequency interval of the measured RF signal step by step to obtain the frequency value within a certain accuracy.

[0014] Furthermore, the optical signals output by the multiple optical channels are detected by the optical detector array, and the DC electrical signals output by the optical detector array are sent to the signal acquisition module. The wavelength position of the optical sideband can be determined according to the size of the electrical signals output by each optical channel, thereby obtaining the frequency of the measured RF signal.

[0015] The present invention also provides a microwave photon instantaneous frequency measurement method, comprising the following steps:

[0016] S100, the laser signal output by the laser is input into the modulator as an optical carrier signal, the frequency is f0, and the frequency of the measured RF signal is f rf The modulator modulates the measured RF signal on the optical carrier signal. The modulated optical signal contains two optical sidebands with frequencies f0±f rf ;

[0017] S200, the optical filter filters the modulated optical signal, and the optical signal after filtering allows only a single optical sideband to pass;

[0018] S300, after the filtered optical signal is amplified by an optical amplifier, the optical signal is divided into multiple optical signals of equal power by a one-to-many optical beam splitter, and the optical signal is attenuated by an optical attenuator on each optical channel;

[0019] S400, the one-to-two optical beam splitter divides the optical signal into two optical signals with completely equal power. The optical signals are transmitted through the first optical path and the second optical path respectively with delayed transmission, generating a fixed optical delay difference τ and an optical phase difference Φ1, and then are combined into one output optical power I1 through the two-in-one optical combiner; the optical phase difference Φ1 generated by the wavelength of the upper sideband is specifically:

[0020] Φ1=2π(f0+f rf )τ

[0021] The output optical power I1 of the two-in-one optical combiner is:

[0022] I1=I+Icos(Φ1)=I+Icos[2π(f0+f rf )τ]

[0023] Wherein, I is the average power, which is the same as the power of the first optical path and the second optical path.

[0024] S500, compare the optical power output by the two-in-one optical combiner with the average power of the optical signal. k is an integer, then the optical power output by the two-in-one optical combiner is greater than the average power of the optical signal I, otherwise the optical power output by the two-in-one optical combiner is less than the average power of the optical signal; thus, the wavelength position interval of the corresponding optical sideband can be determined according to the magnitude of the output optical power, and then the frequency f of the RF signal to be measured can be obtained according to the corresponding relationship between the wavelength and frequency of the optical sideband.rf Specifically:

[0025]

[0026] The interval length f of the frequency of the radio frequency signal to be measured BW1 Specifically:

[0027]

[0028] S600: Calculate the radio frequency signals f to be measured in the multiple optical channels respectively. rf , the optical phase difference Φ1 of each optical channel increases successively, and the delay difference of adjacent optical channels increases by 2 times. The larger the optical delay difference, the smaller the reflection fringe period of the interference output signal intensity in the corresponding optical channel. The optical channel with the largest optical delay difference determines the accuracy of the system frequency measurement, and the frequency interval of the measured RF signal is located step by step to obtain the frequency value within a certain accuracy;

[0029] The minimum frequency interval length f of the radio frequency signal to be tested BWN Specifically:

[0030]

[0031] S700, the optical signals output by the multiple optical channels are detected by the optical detector array, and the DC electrical signals output by the optical detector array are sent to the signal acquisition module. The wavelength position of the optical sideband can be determined according to the size of the electrical signals output by each optical channel, thereby obtaining the frequency of the measured radio frequency signal.

[0032] The advantages of the present invention are: utilizing the advantages of ultra-wideband signal processing of microwave photon technology, modulating the measured radio frequency signal in the optical domain, utilizing multi-path optical channel delayed interference, judging the threshold of the output power value after interference, locating the frequency range of the measured radio frequency signal step by step, obtaining the frequency value within a certain accuracy, and having lower requirements for signal acquisition and data processing. While giving full play to the advantages of microwave photon real-time processing and anti-electromagnetic interference, there is no need for high-speed ultra-wideband radio frequency signal acquisition and processing, which can significantly reduce the amount of system equipment and power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural diagram of a microwave photon instantaneous frequency measurement device according to an embodiment of the present invention;

[0034] Figure 2 It is a curve diagram of the amplitude-frequency response of each channel in the microwave photon instantaneous frequency measurement device according to the embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments:

[0037] Embodiment 1

[0038] like Figure 1 As shown, specifically, a microwave photon instantaneous frequency measurement device is disclosed, including a laser, a modulator, an optical filter, an optical amplifier, a one-to-many optical beam splitter, a multi-path optical channel, an optical detector array and a signal acquisition module connected in sequence;

[0039] The optical channel includes an optical attenuator, a one-to-two optical beam splitter, an optical delay and a two-in-one optical combiner; the input end of the optical attenuator is connected to the output end of the one-to-many optical beam splitter, and the output end of the optical attenuator is connected to the input end of the one-to-two optical beam splitter; the first output end of the one-to-two optical beam splitter is connected to the first input end of the optical combiner through an optical delay to form a first optical path, the second output end of the one-to-two optical beam splitter is connected to the second input end of the optical combiner to form a second optical path, and there is an optical delay difference between the first optical path and the second optical path; the output end of the optical combiner is connected to the input end of the optical detector array; the optical delay difference of the multiple optical channels increases sequentially.

[0040] The laser signal output by the laser is used as an optical carrier signal with a frequency of f0, and the frequency of the measured RF signal is f rf After the optical carrier signal is input into the modulator, the RF signal to be measured is loaded into the RF input terminal of the modulator. The modulator modulates the RF signal to be measured on the optical carrier signal. The modulated optical signal contains two frequency components of the optical sidebands f0±f rf .

[0041] The modulator can work in double-sideband modulation or carrier suppression modulation. Double-sideband modulation can make the spectrum of the optical signal produce symmetrical frequency bands on both sides of the carrier frequency through the interaction of the carrier signal and the modulation signal. The modulated optical signal contains the original optical carrier signal frequency f0 and two sideband frequencies f0±f rf The spectrum of the optical signal after carrier suppression modulation does not contain the original optical carrier signal frequency f0, but only contains two sideband frequencies f0±f rf , without the need for a center carrier component.

[0042] The optical filter filters the modulated optical signal, and the passband of the optical filter is larger than the frequency range of the measured RF signal. Since the output values ​​of the two sidebands will be different after interference, the superposition will affect the threshold judgment of the output optical power value in the later stage, and it is impossible to judge whether the frequency band of the signal falls within the corresponding frequency interval. At the same time, according to the working state of the modulator, the passband position of the optical filter requires that the modulated optical signal can only allow a single optical sideband to pass.

[0043] The optical filter may be an upper sideband filter or a lower sideband filter. In this embodiment, the upper sideband filter is selected as an example. After filtering, only the upper sideband passes through the optical signal. The frequency of the upper sideband included in the optical signal is f0+f rf .

[0044] After the filtered optical signal is amplified by the optical amplifier, it is divided into multiple optical signals of equal power through a one-to-many optical beam splitter. To avoid optical loss and other influencing factors, each optical channel first passes through an optical attenuator to control the attenuation of the optical signal, further ensuring that the optical power of each optical channel is the same. Figure 1 As shown, the optical signal powers on the N optical channels output by the 1×N optical beam splitter are the same, wherein the number of optical channels N is selected appropriately according to the actual frequency measurement accuracy requirement. If the required frequency measurement accuracy is higher, the value of the number of optical channels N is larger.

[0045] The one-to-two optical beam splitter divides the optical signal passing through the optical attenuator into two optical signals with completely equal power. The optical signals are respectively transmitted through the first optical path and the second optical path with delayed transmission, and then combined into one optical signal for output through the two-in-one optical beam combiner. Since the first optical path is connected to the two-in-one optical beam combiner through optical delay, there will be a fixed optical delay difference τ between the first optical path and the second optical path, so that there is a fixed optical phase difference Φ1 between the two signals. The size of the optical phase difference is related to the wavelength of the optical signal. Different wavelengths of optical sidebands correspond to different optical phase differences. Taking the upper sideband as an example, the optical phase difference Φ1 generated by the wavelength of the upper sideband is specifically:

[0046] Φ1=2π(f0+f rf )τ

[0047] The optical powers output by the first optical path and the second optical path after interference superposition by the two-in-one optical combiner are also different. The optical power I1 output by the two-in-one optical combiner is specifically:

[0048] I1=I+Icos(Φ1)=I+Icos[2π(f0+f rf )τ]

[0049] Where I is the average power, which is the same as the power of the first and second optical paths. k is an integer, then the optical power I1 output by the two-in-one optical combiner is greater than the average power I of the optical signal, otherwise the optical power I1 output by the two-in-one optical combiner is less than the average power of the optical signal; thus, the wavelength position interval of the corresponding optical sideband can be determined according to the magnitude of the output optical power, and then the frequency f of the RF signal to be measured can be obtained according to the corresponding relationship between the wavelength and frequency of the optical sideband rf Specifically:

[0050]

[0051] The interval length f of the frequency of the radio frequency signal to be measured BW1 Specifically:

[0052]

[0053] like Figure 2 The amplitude-frequency response curve of each channel in the microwave photon instantaneous frequency measurement device and its position relationship with the corresponding optical signal are shown in Figure 2. Calculate the RF signal f to be measured in multiple optical channels respectively. rf , locate the frequency range of the measured RF signal step by step, and obtain the frequency value within a certain accuracy.

[0054] Since the optical delays of the optical channels are different, the optical delay differences of the optical channels in the present invention increase in sequence, and the delay differences of adjacent optical channels increase by a factor of 2. The larger the optical delay difference, the smaller the reflection fringe period of the interference output signal intensity in the corresponding optical channel, and the smaller the frequency interval length of the optical sideband that can be determined. Therefore, the optical channel with the largest optical delay difference determines the accuracy of the system frequency measurement. The minimum frequency interval length f of the RF signal to be measured BWN Specifically:

[0055]

[0056] The optical delay is a delay fiber or a delay waveguide, which is used to control the transmission time of the optical signal and adjust the propagation delay of the optical signal. When the optical delay adopts a delay fiber, the optical delay is achieved by increasing the length of the optical signal propagation path (i.e., the length of the delay fiber), and the delay amount of the optical delay is directly related to the length of the delay fiber; when the optical delay adopts a delay waveguide, the delay is achieved by designing a special optical waveguide path.

[0057] The optical signals output by multiple optical channels are detected by an optical detector array, which is formed by arranging multiple optical detectors in a matrix or array form, and can simultaneously detect the output power of multiple optical channels. The bandwidth requirements of the optical detectors are very low, and only the DC component needs to be detected. The DC electrical signal output by the optical detector array is sent to the signal acquisition module, and the wavelength position of the optical sideband can be determined according to the size of the electrical signal corresponding to the output of each optical channel, thereby obtaining the frequency of the measured RF signal.

[0058] The present invention discloses the advantages of utilizing microwave photonic technology for ultra-wideband signal processing, modulating the radio frequency signal to be measured in the optical domain, utilizing multi-path optical channel delayed interference, judging the threshold of the output power value after interference, locating the frequency interval of the radio frequency signal to be measured step by step, and quickly confirming the frequency position of the radio frequency signal to be measured within the ultra-wideband frequency range by reconstructing the multiplexed channel division method, and converting the radio frequency signal to a low-frequency range for collection and measurement. There is no need for high-speed ultra-wideband radio frequency signal collection and processing, which can significantly reduce the amount of system equipment and power consumption, and has lower requirements for signal collection and data processing. At the same time, the frequency measuring device has the characteristics of instantaneous operation and can measure the frequency of the radio frequency signal in real time.

[0059] The present invention also provides a microwave photon instantaneous frequency measurement method, comprising the following steps:

[0060] S100, the laser signal output by the laser is input into the modulator as an optical carrier signal, the frequency is f0, and the frequency of the measured RF signal is f rf The modulator modulates the measured RF signal on the optical carrier signal. The modulated optical signal contains two optical sidebands with frequencies f0±f rf ;

[0061] S200, the optical filter filters the modulated optical signal, and the optical signal after filtering allows only a single optical sideband to pass;

[0062] S300, after the filtered optical signal is amplified by an optical amplifier, the optical signal is divided into multiple optical signals of equal power by a one-to-many optical beam splitter, and each optical channel first passes through an optical attenuator to control the attenuation of the optical signal;

[0063] S400, the one-to-two optical beam splitter divides the optical signal into two optical signals with completely equal power. The optical signals are transmitted through the first optical path and the second optical path respectively with delayed transmission, generating a fixed optical phase difference Φ1, and then are combined into one optical output power I1 through the two-in-one optical combiner; the optical phase difference Φ1 generated by the wavelength of the upper sideband is specifically:

[0064] Φ1=2π(f0+f rf )τ

[0065] The output optical power I1 of the two-in-one optical combiner is:

[0066] I1=I+Icos(Φ1)=I+Icos[2π(f0+f rf )τ]

[0067] Where I is the average power, which is the same as the power of the first and second optical paths. k is an integer, then the optical power output by the two-in-one optical combiner is greater than the average power of the optical signal I, otherwise the optical power output by the two-in-one optical combiner is less than the average power of the optical signal; thus, the wavelength position interval of the corresponding optical sideband can be determined according to the magnitude of the output optical power, and then the RF signal to be measured f can be obtained according to the corresponding relationship between the wavelength and frequency of the optical sideband. rf Specifically:

[0068]

[0069] S500, the optical phase difference Φ1 of each optical channel is increased in sequence, and the RF signal f to be measured in the multiple optical channels is calculated respectively. rf , locate the frequency interval of the measured RF signal step by step, and obtain the frequency value within a certain accuracy;

[0070] S600, the optical signals output by the multiple optical channels are detected by the optical detector array, and the DC electric signals output by the optical detector array are sent to the signal acquisition module. The wavelength position of the optical sideband can be determined according to the size of the electric signals output by each optical channel, thereby obtaining the frequency of the measured radio frequency signal.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microwave photon instantaneous frequency measurement device, characterized in that: It comprises a laser, a modulator, an optical filter, an optical amplifier, a one-to-many optical beam splitter, a multi-path optical channel, an optical detector array and a signal acquisition module connected in sequence; the optical channel comprises an optical attenuator, a one-to-two optical beam splitter, an optical delay and a two-in-one optical beam combiner; the input end of the optical attenuator is connected to the output end of the one-to-many optical beam splitter, and the output end of the optical attenuator is connected to the input end of the one-to-two optical beam splitter; the first output end of the one-to-two optical beam splitter is connected to the first input end of the optical beam combiner through an optical delay to form a first optical path, the second output end of the one-to-two optical beam splitter is connected to the second input end of the optical beam combiner to form a second optical path, and there is an optical delay difference between the first optical path and the second optical path; the output end of the optical beam combiner is connected to the input end of the optical detector array; The optical delay differences of the multiple optical channels increase in sequence.

2. The microwave photon instantaneous frequency measuring device according to claim 1, characterized in that: The laser signal output by the laser is used as an optical carrier signal, and the modulator modulates the radio frequency signal to be measured on the optical carrier signal. The modulated optical signal contains frequency components of two optical sidebands.

3. The microwave photon instantaneous frequency measuring device according to claim 2, characterized in that: The modulator working state is double sideband modulation or carrier suppression modulation.

4. The microwave photon instantaneous frequency measuring device according to claim 1, characterized in that: The optical filter is an upper sideband filter or a lower sideband filter.

5. The microwave photon instantaneous frequency measuring device according to claim 1, characterized in that: The one-to-many optical beam splitter divides the optical signal into multiple optical signals of equal power, and the optical signals are attenuated by the optical attenuator on each optical channel.

6. The microwave photon instantaneous frequency measuring device according to claim 5, characterized in that: The one-to-two optical beam splitter divides the optical signal passing through the optical attenuator into two optical signals with completely equal power. The optical signals are respectively transmitted with delay through the first optical path and the second optical path to generate a fixed optical delay difference and optical phase difference, and then combined into one output through the two-in-one optical combiner.

7. The microwave photon instantaneous frequency measuring device according to claim 6, characterized in that: The optical power output by the two-in-one optical combiner is compared with the average power of the optical signal, the wavelength position interval of the corresponding optical sideband is determined according to the magnitude of the output optical power, and then the range of the RF signal to be measured is obtained according to the correspondence between the wavelength and frequency of the optical sideband.

8. The microwave photon instantaneous frequency measuring device according to claim 7, characterized in that: The optical delay difference of the multiple optical channels increases successively, and the delay difference of adjacent optical channels increases by a factor of 2. The larger the optical delay difference, the smaller the reflection fringe period of the interference output signal intensity in the corresponding optical channel. The optical channel with the largest optical delay difference determines the accuracy of the system frequency measurement, and locates the frequency interval of the measured RF signal step by step to obtain the frequency value within a certain accuracy.

9. The microwave photon instantaneous frequency measuring device according to claim 8, characterized in that: The optical signals output by multiple optical channels are detected by the optical detector array, and the DC electrical signals output by the optical detector array are sent to the signal acquisition module. The wavelength position of the optical sideband can be determined according to the size of the electrical signals corresponding to the output of each optical channel, thereby obtaining the frequency of the measured RF signal.

10. The microwave photon instantaneous frequency measurement method according to any one of claims 1 to 9, characterized in that: The following steps are involved: S100, the laser signal output by the laser is input into the modulator as an optical carrier signal, the frequency is f0, and the frequency of the measured RF signal is f rf The modulator modulates the measured RF signal on the optical carrier signal. The modulated optical signal contains two optical sideband frequency components f0±f rf ; S200, the optical filter filters the modulated optical signal, and the optical signal after filtering allows only a single optical sideband to pass; S300, after the filtered optical signal is amplified by an optical amplifier, the optical signal is divided into multiple optical signals of equal power by a one-to-many optical beam splitter, and the optical signal is attenuated by an optical attenuator on each optical channel; S400, the one-to-two optical beam splitter divides the optical signal into two optical signals with completely equal power. The optical signals are transmitted through the first optical path and the second optical path respectively with delayed transmission, generating a fixed optical delay difference τ and an optical phase difference Φ1, and then are combined into one output optical power I1 through the two-in-one optical combiner; the optical phase difference Φ1 generated by the wavelength of the upper sideband is specifically: Φ1=2π(f0+f rf )t The output optical power I1 of the two-in-one optical combiner is: I1=I+Icos(Φ1)=I+Icos[2π(f0+f rf )t] Wherein, I is the average power, which is the same as the power of the first optical path and the second optical path. S500, compare the optical power output by the two-in-one optical combiner with the average power of the optical signal. k is an integer, then the optical power output by the two-in-one optical combiner is greater than the average power of the optical signal I, otherwise the optical power output by the two-in-one optical combiner is less than the average power of the optical signal; thus, the wavelength position interval of the corresponding optical sideband can be determined according to the magnitude of the output optical power, and then the frequency f of the RF signal to be measured can be obtained according to the corresponding relationship between the wavelength and frequency of the optical sideband. rf Specifically: The interval length f of the frequency of the radio frequency signal to be measured BW1 Specifically: S600: Calculate the radio frequency signals f to be measured in the multiple optical channels respectively. rf , the optical phase difference Φ1 of each optical channel increases successively, and the delay difference of adjacent optical channels increases by 2 times. The larger the optical delay difference, the smaller the reflection fringe period of the interference output signal intensity in the corresponding optical channel. The optical channel with the largest optical delay difference determines the accuracy of the system frequency measurement, and the frequency interval of the measured RF signal is located step by step to obtain the frequency value within a certain accuracy; The minimum frequency interval length f of the radio frequency signal to be tested BWN Specifically: S700, the optical signals output by the multiple optical channels are detected by the optical detector array, and the DC electrical signals output by the optical detector array are sent to the signal acquisition module. The wavelength position of the optical sideband can be determined according to the size of the electrical signals output by each optical channel, thereby obtaining the frequency of the measured radio frequency signal.

Images