Microwave frequency measurement method and device based on multi-channel optical path phase detection

Abstract

The present invention discloses a microwave frequency measurement method based on multi-channel optical path phase discrimination. The method comprises the following steps: S1, dividing the optical frequency comb signal into a first measurement channel, a second measurement channel and a reference channel, and introducing different first-order delays to the optical signals of the measurement channels, and then combining the three-channel optical signals into a first-order delayed optical frequency comb; S2, modulating the microwave signal to be measured on the intensity envelope of the first-order delayed optical frequency comb; S3, dividing the modulated optical signal again according to the same channel division method, and introducing the same second-order delay to the optical signals of the measurement channels; S4, photoelectrically converting and extracting the phase of the electrical signals of the two measurement channels relative to the electrical signal of the reference channel; S5, solving the frequency of the microwave signal to be measured based on the phase and delay. The present invention also discloses a microwave frequency measurement device based on multi-channel optical path phase discrimination. The present invention can reduce the requirements of microwave frequency measurement on system response bandwidth and high-speed sampling, and has a simple structure and good real-time performance.

Description

Technical Field

[0001] The present invention relates to a microwave frequency measurement method, in particular to a microwave frequency measurement method assisted by microwave photons. Background Art

[0002] With the continued advancement of technologies such as radar detection, electronic countermeasures, and spectrum monitoring, the demand for fast and high-precision measurement of microwave signal frequencies is growing. To achieve efficient spectrum management, existing equipment must be equipped with real-time perception of the electromagnetic environment and accurate monitoring of spectrum usage. Therefore, developing microwave frequency measurement technology with real-time and high-precision capabilities is crucial for improving electromagnetic spectrum perception and supporting dynamic spectrum resource management and security control.

[0003] Currently, traditional microwave frequency measurement methods primarily include swept spectrum analysis, phase comparison, delay line frequency discrimination, and digital signal processing. These methods suffer from common issues such as slow measurement speed, limited frequency range, high reliance on high-sampling-rate analog-to-digital converters, and complex hardware structures, making them incapable of meeting the demands of next-generation high-speed, broadband, and real-time frequency measurement. In recent years, advances in photonic technology have provided new solutions for high-performance frequency measurement. In particular, technologies such as photon sampling, optical delay lines, and microwave photon modulation have demonstrated unique advantages in broadband, reconfigurability, electromagnetic interference immunity, and system integrability. However, existing frequency measurement methods based on photonic structures still rely on continuous scanning or interferometry, which are limited by complex systems, slow response, and high laser stability requirements. Therefore, a microwave frequency measurement method and device with a simple structure, fast response, adjustable accuracy, and easy integration is urgently needed to meet the future demand for high-performance frequency sensing in dynamic spectrum environments. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a microwave frequency measurement method based on multi-channel optical path phase detection, which can reduce the requirements for system response bandwidth and high-speed sampling, and does not require high-speed analog-to-digital conversion, thereby reducing the requirements for digital signal processing. It has the advantages of simple structure and good real-time performance.

[0005] The present invention specifically adopts the following technical solutions to solve the above technical problems:

[0006] A microwave frequency measurement method based on multi-channel optical path phase detection includes the following steps:

[0007] S1. Divide the optical frequency comb signal into three channels: the first measurement channel, the second measurement channel, and the reference channel. The optical signal of each channel contains a different set of comb teeth; and introduce different first-order delays to the optical signals of the first measurement channel and the second measurement channel respectively. 、 ,Then the optical signals of the three channels are combined into the first-stage delayed optical frequency comb;

[0008] S2, modulating the microwave signal to be measured onto the intensity envelope of the first-stage delayed optical frequency comb;

[0009] S3, the obtained modulated optical signal is divided into a first measurement channel, a second measurement channel, and a reference channel according to the same channel division method; and the same second-order delay is introduced into the optical signals of the first measurement channel and the second measurement channel respectively. 、 ;

[0010] S4, convert the optical signals of the three channels into corresponding electrical signals respectively, and extract the phase of the electrical signals of the first measurement channel and the second measurement channel relative to the electrical signal of the reference channel respectively by phase detection. 、 ; The phase discrimination accuracy of the phase discrimination satisfy , is the repetition frequency of the optical frequency comb;

[0011] S5. Calculate the frequency of the microwave signal to be measured by the following formula :

[0012]

[0013] Where, is the rounding function, Represents the decimal part of the replacement expression.

[0014] Furthermore, according to the formula: , by adjusting the first-level delay 、 The upper limit of the frequency of the measurable microwave signal is adjusted by the difference between .

[0015] According to the same inventive concept, the following technical solutions can also be obtained:

[0016] A microwave frequency measurement device based on multi-channel optical path phase detection, comprising:

[0017] The first delay module is used to divide the optical frequency comb signal into three channels: the first measurement channel, the second measurement channel, and the reference channel. The optical signal of each channel contains a different set of comb teeth; and different first-order delays are introduced into the optical signals of the first measurement channel and the second measurement channel respectively. 、 ,Then the optical signals of the three channels are combined into the first-stage delayed optical frequency comb;

[0018] An intensity modulation module, used to modulate the microwave signal to be measured onto the intensity envelope of the first-stage delayed optical frequency comb;

[0019] The second delay module is used to divide the obtained modulated optical signal into the first measurement channel, the second measurement channel, and the reference channel according to the same channel division method; and introduce the same second-level delay to the optical signals of the first measurement channel and the second measurement channel respectively. 、 ;

[0020] The photoelectric conversion and phase detection module is used to convert the optical signals of the three channels into corresponding electrical signals, and extract the phase of the electrical signals of the first measurement channel and the second measurement channel relative to the electrical signal of the reference channel by phase detection. 、 ; The phase discrimination accuracy of the phase discrimination satisfy , is the repetition frequency of the optical frequency comb;

[0021] The calculation module is used to solve the frequency of the microwave signal to be measured through the following formula :

[0022]

[0023] Where, is the rounding function, Represents the decimal part of the replacement expression.

[0024] Furthermore, according to the formula: , by adjusting the first-level delay 、 The upper limit of the frequency of the measurable microwave signal is adjusted by the difference between .

[0025] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0026] The present invention reduces the requirements of microwave frequency measurement on system response bandwidth and high-speed sampling through optical domain down-conversion, eliminates the need for high-speed analog-to-digital conversion, reduces the requirements for digital signal processing, and has the advantages of simple structure and good real-time performance. Based on the advantages of good optical domain parallelism and reconfigurability, the present invention can achieve a compact system structure and can further realize system integration through photonic integration technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a schematic diagram of the structural principle of the microwave frequency measurement device based on multi-channel optical path phase detection of the present invention. DETAILED DESCRIPTION

[0028] In view of the shortcomings of the existing technology, the solution of the present invention is to reduce the requirements for bandwidth and high-speed sampling through optical domain down-conversion and achieve a more compact system structure.

[0029] The microwave frequency measurement method based on multi-channel optical path phase discrimination proposed in the present invention comprises the following steps:

[0030] S1. Divide the optical frequency comb signal into three channels: the first measurement channel, the second measurement channel, and the reference channel. The optical signal of each channel contains a different set of comb teeth; and introduce different first-order delays to the optical signals of the first measurement channel and the second measurement channel respectively. 、 ,Then the optical signals of the three channels are combined into the first-stage delayed optical frequency comb;

[0031] S2, modulating the microwave signal to be measured onto the intensity envelope of the first-stage delayed optical frequency comb;

[0032] S3, the obtained modulated optical signal is divided into a first measurement channel, a second measurement channel, and a reference channel according to the same channel division method; and the same second-order delay is introduced into the optical signals of the first measurement channel and the second measurement channel respectively. 、 ;

[0033] S4, convert the optical signals of the three channels into corresponding electrical signals respectively, and extract the phase of the electrical signals of the first measurement channel and the second measurement channel relative to the electrical signal of the reference channel respectively by phase detection. 、 ; The phase discrimination accuracy of the phase discrimination satisfy , is the repetition frequency of the optical frequency comb;

[0034] S5. Calculate the frequency of the microwave signal to be measured by the following formula :

[0035]

[0036] Where, is the rounding function, Represents the decimal part of the replacement expression.

[0037] The microwave frequency measurement device based on multi-channel optical path phase detection proposed in the present invention includes:

[0038] The first delay module is used to divide the optical frequency comb signal into three channels: the first measurement channel, the second measurement channel, and the reference channel. The optical signal of each channel contains a different set of comb teeth; and different first-order delays are introduced into the optical signals of the first measurement channel and the second measurement channel respectively. 、 ,Then the optical signals of the three channels are combined into the first-stage delayed optical frequency comb;

[0039] An intensity modulation module, used to modulate the microwave signal to be measured onto the intensity envelope of the first-stage delayed optical frequency comb;

[0040] The second delay module is used to divide the obtained modulated optical signal into the first measurement channel, the second measurement channel, and the reference channel according to the same channel division method; and introduce the same second-level delay to the optical signals of the first measurement channel and the second measurement channel respectively. 、 ;

[0041] The photoelectric conversion and phase detection module is used to convert the optical signals of the three channels into corresponding electrical signals, and extract the phase of the electrical signals of the first measurement channel and the second measurement channel relative to the electrical signal of the reference channel by phase detection. 、 ; The phase discrimination accuracy of the phase discrimination satisfy , is the repetition frequency of the optical frequency comb;

[0042] The calculation module is used to solve the frequency of the microwave signal to be measured through the following formula :

[0043]

[0044] Where, is the rounding function, Represents the decimal part of the replacement expression.

[0045] To facilitate public understanding, the technical solution of the present invention is described in detail below with reference to the accompanying drawings:

[0046] The present invention is based on a microwave frequency measurement device with a multi-channel optical path phase detection, and its basic structure is as follows: Figure 1 As shown, it includes two wavelength division multiplexers, a wavelength demultiplexer, an intensity modulator, three photodetectors, two phase detectors, and a solution module (not shown in the figure).

[0047] like Figure 1As shown, first, the optical frequency comb signal is divided into three channels by a wavelength division multiplexer: a first measurement channel, a second measurement channel, and a reference channel. The optical signal of each channel contains a different set of comb teeth. Then, different first-order delays are introduced into the optical signals of the first measurement channel and the second measurement channel through delay lines of different lengths, and the optical signal of the reference channel is not delayed. Then, the optical signals of the first and second measurement channels with the first-order delay introduced are combined with the optical signal of the reference channel to form a first-order delayed optical frequency comb through a wavelength division multiplexer. The microwave signal to be measured is modulated on the intensity envelope of the first-order delayed optical frequency comb through an intensity modulator. The multiplexer divides the obtained modulated optical signal into a first measurement channel, a second measurement channel, and a reference channel using the same channel swapping method. The same second-order delay is then introduced into the optical signals of the first and second measurement channels via delay lines of the same length, while the optical signal of the reference channel is not delayed. The optical signals of the three channels are then photoelectrically detected to obtain corresponding electrical signals. Two phase detectors are used to extract the phase information of the electrical signals of the first and second measurement channels relative to the electrical signal of the reference channel. Finally, the frequency information of the microwave signal to be measured is calculated based on the known delay and the measured phase information.

[0048] The optical frequency comb signal can be expressed as:

[0049]

[0050] in, The optical frequency comb Root comb teeth, For the The complex envelope amplitude of each comb tooth, is the carrier envelope offset frequency of the optical frequency comb, is the repetition frequency of the optical frequency comb.

[0051] After introducing the preset first delay, the optical signals of the two measurement channels can be expressed as:

[0052]

[0053] in, For the i The first-order delay introduced by each measurement channel.

[0054] The intensity of the microwave signal to be measured is modulated onto the first-stage delayed optical frequency comb. The modulation form is small signal modulation. The output optical field after modulation can be approximated as:

[0055]

[0056] in, is the frequency of the microwave signal to be measured, M is the modulation depth of intensity modulation.

[0057] Introducing a second level of delay into the modulated optical signal , at this time the optical signals of the two measurement channels are expressed as:

[0058]

[0059] Each optical signal is sent to a low-speed photoelectric detector for photoelectric conversion. , then the photoelectric conversion will realize the down-conversion of the microwave signal to be measured. At this time, the photocurrent signals output by the two measurement channels can be expressed as:

[0060] in, is the electro-optical conversion coefficient of the photodetector; K is a non-negative integer that satisfies .

[0061] The first i The phase of the measurement channel photocurrent relative to the reference channel photocurrent is:

[0062]

[0063] Due to the phase wrapping of the phase detector, the actual phase of the photocurrent signal is:

[0064]

[0065] in, , The rounding function.

[0066] Equation (7) can be expressed in vector form:

[0067]

[0068] Pick and make 、 satisfy ,at this time ,in It is the upper limit of the frequency of microwave signals that can be measured by the system.

[0069] use Can be obtained K :

[0070]

[0071] To ensure K The value is unique and the phase detection accuracy is The following conditions must be met:

[0072]

[0073] that is

[0074]

[0075] Obtain K Then, combine the following formula:

[0076]

[0077] It can be seen that:

[0078]

[0079] in, Represents the decimal part of the replacement expression.

[0080] According to formula (14), the microwave frequency to be measured can be obtained .

[0081] Due to the first-level delay 、 The upper limit of the frequency of microwave signals that can be measured by the system Satisfaction between Therefore, the first-level delay can be further adjusted according to actual needs. 、 The upper limit of the frequency of the measurable microwave signal is adjusted by the difference between (i.e. the frequency measurement range of the system).

Claims

1. A microwave frequency measurement method based on multi-channel optical path phase detection, characterized in that: The following steps are involved: S1. Divide the optical frequency comb signal into three channels: the first measurement channel, the second measurement channel, and the reference channel. The optical signal of each channel contains a different set of comb teeth; and introduce different first-order delays to the optical signals of the first measurement channel and the second measurement channel respectively. 、 ,Then the optical signals of the three channels are combined into the first-stage delayed optical frequency comb; S2, modulating the microwave signal to be measured onto the intensity envelope of the first-stage delayed optical frequency comb; S3, the obtained modulated optical signal is divided into a first measurement channel, a second measurement channel, and a reference channel according to the same channel division method; and the same second-order delay is introduced into the optical signals of the first measurement channel and the second measurement channel respectively. 、 ; S4, convert the optical signals of the three channels into corresponding electrical signals respectively, and extract the phase of the electrical signals of the first measurement channel and the second measurement channel relative to the electrical signal of the reference channel respectively by phase detection. 、 ; The phase discrimination accuracy of the phase discrimination satisfy , is the repetition frequency of the optical frequency comb; S5. Calculate the frequency of the microwave signal to be measured by the following formula : ； Where, is the rounding function, Represents the decimal part of the replacement expression.

2. The microwave frequency measurement method based on multi-channel optical path phase detection as claimed in claim 1, characterized in that: According to the formula: , by adjusting the first-level delay 、 The upper limit of the frequency of the measurable microwave signal is adjusted by the difference between .

3. A microwave frequency measurement device based on multi-channel optical path phase detection, characterized in that: include: The first delay module is used to divide the optical frequency comb signal into three channels: the first measurement channel, the second measurement channel, and the reference channel. The optical signal of each channel contains a different set of comb teeth; and different first-order delays are introduced into the optical signals of the first measurement channel and the second measurement channel respectively. 、 ,Then the optical signals of the three channels are combined into the first-stage delayed optical frequency comb; An intensity modulation module, used to modulate the microwave signal to be measured onto the intensity envelope of the first-stage delayed optical frequency comb; The second delay module is used to divide the obtained modulated optical signal into the first measurement channel, the second measurement channel, and the reference channel according to the same channel division method; and introduce the same second-level delay to the optical signals of the first measurement channel and the second measurement channel respectively. 、 ; The photoelectric conversion and phase detection module is used to convert the optical signals of the three channels into corresponding electrical signals, and extract the phase of the electrical signals of the first measurement channel and the second measurement channel relative to the electrical signal of the reference channel by phase detection. 、 ; The phase discrimination accuracy of the phase discrimination satisfy , is the repetition frequency of the optical frequency comb; The calculation module is used to solve the frequency of the microwave signal to be measured through the following formula : ； Where, is the rounding function, Represents the decimal part of the replacement expression.

4. The microwave frequency measurement device based on multi-channel optical path phase detection as claimed in claim 3, characterized in that: According to the formula: , by adjusting the first-level delay 、 The upper limit of the frequency of the measurable microwave signal is adjusted by the difference between .

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