Radio frequency pulse width measurement device and method based on microwave photonics technology

Abstract

The application discloses a microwave photon technology-based radio frequency pulse width measuring device and method, belongs to the microwave photon technology field, and solves the problem that the envelope detector is used to measure radio frequency pulse parameters in the prior art, and it is difficult to realize the measurement requirement of the ultra-wideband radio frequency signal; the application utilizes the advantage of the microwave photon technology ultra-wideband signal processing, processes the ultra-wideband radio frequency pulse signal in the optical domain through two kinds of modulation modes, utilizes the beat frequency output of the photoelectric detector to output two low-frequency edge pulse signals, converts the to-be-measured radio frequency pulse signal in the ultra-wideband frequency range into a low-frequency signal range for collection and measurement, and the ultra-wideband, fast pulse width measurement of the ultra-wideband radio frequency signal can be realized without the collection and processing capacity of the high-speed ultra-wideband radio frequency signal.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microwave photonics, and relates to a radio frequency pulse width measuring device and method based on microwave photonics. BACKGROUND

[0002] The parameters of a traditional modulated radio frequency pulse include pulse width, rise time, fall time and the like, and the measuring method mainly relies on an envelope detector to detect the envelope of the radio frequency pulse, and then further signal processing is performed. For example, an application patent with the application publication number CN110620571A discloses an on-off keying demodulator applied to an ultra-wideband radio frequency receiver, which adopts an envelope detection method for demodulation. The signal is first squared to obtain a square current, and then the current is converted into a voltage by taking RC as a load. Meanwhile, the RC circuit can be used as a low-pass filter circuit to filter out the high-frequency components of the circuit to obtain an envelope signal. The envelope detection of the radio frequency pulse has high requirements for the sensitivity and linearity characteristics of the detector, and the nonlinear characteristics of the detector will cause the detected waveform to be blurred. Moreover, the measurement results are significantly different when the same signal is detected by different detectors or even the same detector but at different sampling rates. With the continuous development of electronic systems, the ultra-wideband radio frequency signal transmission and processing capability is continuously improved, and the working frequency band of the electronic system is getting higher and higher. The working bandwidth has gradually expanded to the millimeter wave frequency band, and the instantaneous bandwidth has been expanded to several GHz or even 10GHz. The challenge of ultra-wideband radio frequency signals to the integration and design of the detection device is also getting bigger and bigger.

[0003] Microwave photonics is a cross-fusion technology that converts microwave signals into the optical domain and realizes signal control and processing through optical methods. By modulating the microwave signal onto the optical signal, microwave signal processing is realized in the optical domain, which has the advantages of large bandwidth, adjustable frequency band, low loss, strong anti-electromagnetic interference capability and the like. It is an indispensable important module in the next generation of wireless communication, radar detection, satellite communication, deep space exploration and satellite payload electronic equipment. Based on microwave photonics technology, the measurement requirements of ultra-wideband radio frequency signal parameters can be effectively met. In order to meet the actual application requirements of ultra-wideband, fast and anti-electromagnetic interference, it is particularly important to develop and develop a radio frequency pulse width measuring device based on microwave photonics technology. SUMMARY

[0004] The technical scheme of the application is used to solve the problem that the prior art uses an envelope detector to measure radio frequency pulse parameters, which is difficult to meet the measurement requirements of ultra-wideband radio frequency signals.

[0005] The application solves the above technical problems through the following technical scheme:

[0006] The application discloses a radio frequency pulse width measuring device based on microwave photon technology, which comprises a laser, a modulation unit and a detection unit connected in sequence.

[0007] The detection unit comprises a third optical coupler, a first band-pass filter, a second band-pass filter, a second adjustable optical delay line, a first photodetector, a second photodetector and a second radio frequency power divider; the input end of the third optical coupler is connected with the output end of the second optical coupler, the first output end of the third optical coupler is connected with the first band-pass filter and the first photodetector in sequence to form a first detection light path, the output end of the first photodetector is connected with the first input end of the second radio frequency power divider, the second output end of the third optical coupler is connected with the second band-pass filter, the second adjustable optical delay line and the second photodetector in sequence to form a second detection light path, and the output end of the second photodetector is connected with the second input end of the second radio frequency power divider.

[0008] Further, the first radio frequency power divider divides the radio frequency pulse signal to be detected into two radio frequency signals with equal power and equal phase, and loads the two radio frequency signals on the amplitude modulator and the phase modulator respectively to perform amplitude modulation on the first modulation light path and phase modulation on the second modulation light path respectively.

[0009] Further, the working state of the amplitude modulator and the phase modulator can be double sideband modulation or carrier suppression modulation.

[0010] Further, the acousto-optic frequency shifter performs frequency modulation on the phase-modulated optical signal, and the first adjustable optical delay line performs delay on the amplitude-modulated optical signal to keep the optical paths of the optical signals on the first modulation light path and the second modulation light path consistent.

[0011] Furthermore, the second optical coupler combines the first and second modulated optical paths to output a single optical signal, which includes an amplitude-modulated optical signal and a phase-modulated optical signal.

[0012] Furthermore, the third optical coupler splits the single optical signal output by the combined output into two optical signals of equal power, which are then sent to the first detection optical path and the second detection optical path, respectively.

[0013] Furthermore, the first bandpass filter and the second bandpass filter have opposite bandpass performance. When the first bandpass filter is an upper sideband filter, the second bandpass filter is a lower sideband filter; when the first bandpass filter is a lower sideband filter, the second bandpass filter is an upper sideband filter.

[0014] Furthermore, the second adjustable optical delay line delays the filtered optical signal, and the first and second detection optical paths generate an optical delay difference; the first and second photodetectors beat to output low-frequency pulse signals, the frequency of which is the frequency shift amount of the acousto-optic frequency shifter, the low-frequency pulse signals output by the first and second photodetectors have a phase difference of 180° and a delay difference in pulse timing, and the delay difference is adjusted by the second adjustable optical delay line.

[0015] Furthermore, the second RF power divider combines the first and second detection optical paths to output a single RF pulse signal, and obtains the pulse time width of the RF pulse signal under test by low-rate acquisition and counting.

[0016] The present invention also provides a method for measuring radio frequency pulse width based on microwave photonics technology, comprising the following steps:

[0017] S100. The laser signal output by the laser is used as the optical carrier signal. The first optical coupler splits the optical carrier signal into two optical signals with equal power, which are then sent to the first modulation optical path and the second modulation optical path, respectively.

[0018] S200, the first radio frequency power divider divides the radio frequency pulse signal under test into two radio frequency signals with equal power and equal phase, which are loaded onto the amplitude modulator and the phase modulator respectively, to perform amplitude modulation on the first modulation optical path and phase modulation on the second modulation optical path respectively;

[0019] S300, the acousto-optic frequency shifter performs frequency shift modulation on the phase-modulated optical signal, and the first adjustable optical delay line delays the amplitude-modulated optical signal, keeping the optical path length of the optical signals on the first and second modulation optical paths consistent.

[0020] S400 and the second optical coupler combine the first and second modulation optical paths to output a single optical signal, so that the single optical signal output by the modulation unit includes an amplitude-modulated optical signal and a phase-modulated optical signal.

[0021] S500 and the third optical coupler split the single optical signal output from the combined output into two optical signals of equal power, which are then sent to the first and second detection optical paths, respectively. The first and second bandpass filters filter the optical signals. When the first bandpass filter allows the upper sideband of the optical signal to pass, the second bandpass filter allows the lower sideband of the optical signal to pass.

[0022] S600 and the second adjustable optical delay line delay the filtered optical signal, the first detection optical path and the second detection optical path generate an optical delay difference, and the first photodetector and the second photodetector beat frequency to output a low frequency pulse signal;

[0023] The S700 and the second RF power divider combine the first and second detection optical paths to output a single RF pulse signal. The pulse time width of the RF pulse signal under test is obtained by low-rate acquisition and counting.

[0024] The advantages of this invention are as follows: This invention utilizes the advantages of microwave photonics technology for ultra-wideband signal processing, and processes ultra-wideband radio frequency pulse signals in the optical domain through two modulation methods. It uses a photodetector to output two low-frequency edge pulse signals by frequency conversion, and converts the radio frequency pulse signal under test in the ultra-wideband frequency range to the range of low-frequency signals for acquisition and measurement. It can achieve ultra-wideband and fast pulse width measurement of ultra-wideband radio frequency signals without the need for high-speed ultra-wideband radio frequency signal acquisition and processing capabilities. Attached Figure Description

[0025] Figure 1 This is a structural diagram of the radio frequency pulse width measurement device based on microwave photonics technology according to an embodiment of the present invention;

[0026] Figure 2 This is a frequency domain schematic diagram of the modulation signal of the radio frequency pulse width measurement device based on microwave photonics technology according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0029] Example 1

[0030] like Figure 1 As shown, specifically, a radio frequency pulse width measurement device based on microwave photonics technology is disclosed, including a laser, a modulation unit and a detection unit connected in sequence;

[0031] The modulation unit includes a first optical coupler, a first radio frequency power divider, an amplitude modulator, a phase modulator, a first tunable optical delay line, an acousto-optic frequency shifter, and a second optical coupler. The input terminal of the first optical coupler is connected to the output terminal of the laser. The first output terminal of the first optical coupler is sequentially connected to the amplitude modulator and the first tunable optical delay line to form a first modulation optical path. The output terminal of the first tunable optical delay line is connected to the first input terminal of the second optical coupler. The second output terminal of the first optical coupler is sequentially connected to the phase modulator and the acousto-optic frequency shifter to form a second modulation optical path. The output terminal of the acousto-optic frequency shifter is connected to the second input terminal of the second optical coupler. The first output terminal of the first radio frequency power divider is connected to the radio frequency input terminal of the amplitude modulator, and the second output terminal of the first radio frequency power divider is connected to the radio frequency input terminal of the phase modulator.

[0032] The detection unit includes a third optical coupler, a first bandpass filter, a second bandpass filter, a second adjustable optical delay line, a first photodetector, a second photodetector, and a second radio frequency power divider. The input terminal of the third optical coupler is connected to the output terminal of the second optical coupler. The first output terminal of the third optical coupler is sequentially connected to the first bandpass filter and the first photodetector to form a first detection optical path. The output terminal of the first photodetector is connected to the first input terminal of the second radio frequency power divider. The second output terminal of the third optical coupler is sequentially connected to the second bandpass filter, the second adjustable optical delay line, and the second photodetector to form a second detection optical path. The output terminal of the second photodetector is connected to the second input terminal of the second radio frequency power divider.

[0033] The laser signal output by the laser is used as an optical carrier signal. The first optical coupler splits the optical carrier signal into two optical signals with equal power, which are then sent to the first modulation optical path and the second modulation optical path, respectively.

[0034] The first RF power divider splits the RF pulse signal under test into two RF signals of equal power and phase, which are then loaded onto an amplitude modulator and a phase modulator, respectively, to perform amplitude modulation on the first modulation optical path and phase modulation on the second modulation optical path. The optical signal after amplitude modulation contains two optical sidebands with the same phase, and the optical signal after phase modulation contains two optical sidebands with a 180° phase difference, such as... Figure 2 As shown.

[0035] The amplitude modulator and phase modulator can operate in either double-sideband modulation (SBMM) or carrier-suppressed modulation (CSCM). SBMM, through the combined action of the carrier signal and the modulating signal, creates symmetrical frequency bands on both sides of the carrier frequency in the optical signal spectrum. The modulated optical signal contains the original optical carrier signal frequency as well as the two sideband frequencies. In contrast, the optical signal spectrum after carrier-suppressed modulation does not contain the original optical carrier signal frequency; it only contains the two sideband frequencies and does not require a center carrier component.

[0036] The acousto-optic frequency shifter performs frequency shift modulation on the phase-modulated optical signal. The frequency shift amount is considered based on the bandwidth of the photodetector and the reduction of the sampling rate at the back end of the measurement device system. This is used to achieve heterodyne detection and avoid the influence of the zero-frequency component on the output in the case of zero-difference detection without frequency shift. Figure 2 As shown, in this embodiment, the selectable frequency shift amount is from tens of MHz to hundreds of MHz.

[0037] The first adjustable optical delay line delays the amplitude-modulated optical signal to keep the optical path length of the optical signals on the first and second modulation optical paths consistent.

[0038] The second optical coupler combines the first and second modulation optical paths to output a single optical signal, so that the single optical signal output by the modulation unit contains both amplitude-modulated and phase-modulated optical signals. This invention combines the two optical signals (amplitude-modulated and phase-modulated) to ensure that the single optical signal output by the modulation unit simultaneously contains both modulation signals. This allows each optical signal within the detection unit to possess the combined characteristics of both modulation signals, effectively enabling the verification and utilization of the modulation effects brought about by different modulation signals.

[0039] The third optical coupler splits the combined single-channel optical signal into two optical signals of equal power, which are then fed into the first and second detection optical paths, respectively. The first and second bandpass filters filter the optical signals. Since the output values ​​of the two sidebands will differ after interference, their superposition will affect the threshold judgment of the output optical power value, making it impossible to determine whether the frequency band of the signal falls within the corresponding frequency range. Therefore, the passband position of the bandpass filter requires that the modulated optical signal can only allow a single optical sideband to pass through.

[0040] The first bandpass filter and the second bandpass filter have opposite bandpass performance, such as... Figure 2 As shown, when the first bandpass filter is the upper sideband filter, the second bandpass filter is the lower sideband filter; when the first bandpass filter is the lower sideband filter, the second bandpass filter is the upper sideband filter, so that the signals filtered out by the upper and lower paths are different. In this way, when the subsequent photodetector beats and outputs the signal, the opposite phases can be canceled out when the circuit is combined.

[0041] The second adjustable optical delay line delays the filtered optical signal, creating an optical delay difference between the first and second detection optical paths. The first and second photodetectors beat-frequency output low-frequency pulse signals, the frequency of which is the frequency shift amount of the acousto-optic frequency shifter. The low-frequency pulse signals output by the first and second photodetectors have a 180° phase difference and a delay difference in pulse timing, which can be adjusted by the second adjustable optical delay line. Since the combined optical signal from the modulation unit contains two modulation methods, the beat-frequency output method can convert the measured RF pulse signal into a low-frequency pulse signal. This allows the measured RF pulse signal within the ultra-wideband frequency range to be converted to a low-frequency range for acquisition and measurement, eliminating the need for high-speed ultra-wideband RF signal acquisition and processing. This significantly reduces the number of system devices and power consumption, and lowers the requirements for signal acquisition and data processing. Furthermore, this frequency measurement device features instantaneous operation, enabling real-time measurement of RF signal frequencies.

[0042] The second RF power divider combines the first and second detection optical paths to output a single RF pulse signal. Since the two low-frequency pulse signals are opposite and have a time delay difference, they are superimposed and combined to form two narrow RF pulses. The timing position of the pulses corresponds to the leading and trailing edges of the RF pulse signal under test. At this time, the carrier frequency of the pulse is a low-frequency signal. The pulse time width of the RF pulse signal under test is then determined by low-rate acquisition and counting.

[0043] The measurement device provided by this invention can be implemented on a chip through photonic integration, which better meets the practical application requirements of ultra-wideband, anti-electromagnetic interference and fast response.

[0044] This invention utilizes the advantages of microwave photonics technology for ultra-wideband signal processing. It processes ultra-wideband radio frequency pulse signals in the optical domain through two modulation methods and uses a photodetector to output two low-frequency edge pulse signals. The radio frequency pulse signal under test in the ultra-wideband frequency range is converted to the range of low-frequency signals for acquisition and measurement. It can achieve ultra-wideband and fast pulse width measurement of ultra-wideband radio frequency signals without the need for high-speed ultra-wideband radio frequency signal acquisition and processing capabilities.

[0045] The present invention also provides a method for measuring radio frequency pulse width based on microwave photonics technology, comprising the following steps:

[0046] S100. The laser signal output by the laser is used as the optical carrier signal. The first optical coupler splits the optical carrier signal into two optical signals with equal power, which are then sent to the first modulation optical path and the second modulation optical path, respectively.

[0047] S200, the first radio frequency power divider divides the radio frequency pulse signal under test into two radio frequency signals with equal power and equal phase, which are loaded onto the amplitude modulator and the phase modulator respectively, to perform amplitude modulation on the first modulation optical path and phase modulation on the second modulation optical path respectively;

[0048] S300, the acousto-optic frequency shifter performs frequency shift modulation on the phase-modulated optical signal, and the first adjustable optical delay line delays the amplitude-modulated optical signal, keeping the optical path length of the optical signals on the first and second modulation optical paths consistent.

[0049] S400 and the second optical coupler combine the first and second modulation optical paths to output a single optical signal, so that the single optical signal output by the modulation unit includes an amplitude-modulated optical signal and a phase-modulated optical signal.

[0050] S500 and the third optical coupler split the single optical signal output from the combined output into two optical signals of equal power, which are then sent to the first and second detection optical paths, respectively. The first and second bandpass filters filter the optical signals. When the first bandpass filter allows the upper sideband of the optical signal to pass, the second bandpass filter allows the lower sideband of the optical signal to pass.

[0051] S600 and the second adjustable optical delay line delay the filtered optical signal, the first detection optical path and the second detection optical path generate an optical delay difference, and the first photodetector and the second photodetector beat frequency to output a low frequency pulse signal;

[0052] The S700 and the second RF power divider combine the first and second detection optical paths to output a single RF pulse signal. The pulse time width of the RF pulse signal under test is obtained by low-rate acquisition and counting.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A radio frequency pulse width measurement device based on microwave photonics technology, characterized in that, The system includes a laser, a modulation unit, and a detection unit connected in sequence. The modulation unit includes a first optical coupler, a first radio frequency power divider, an amplitude modulator, a phase modulator, a first tunable optical delay line, an acousto-optic frequency shifter, and a second optical coupler. The input terminal of the first optical coupler is connected to the output terminal of the laser. The first output terminal of the first optical coupler is connected in sequence to the amplitude modulator and the first tunable optical delay line to form a first modulation optical path. The output terminal of the first tunable optical delay line is connected to the first input terminal of the second optical coupler. The second output terminal of the first optical coupler is connected in sequence to the phase modulator and the acousto-optic frequency shifter to form a second modulation optical path. The output terminal of the acousto-optic frequency shifter is connected to the second input terminal of the second optical coupler. The first output terminal of the first radio frequency power divider is connected to the radio frequency input terminal of the amplitude modulator, and the second output terminal of the first radio frequency power divider is connected to the radio frequency input terminal of the phase modulator. The detection unit includes a third optical coupler, a first bandpass filter, a second bandpass filter, a second adjustable optical delay line, a first photodetector, a second photodetector, and a second radio frequency power divider. The input terminal of the third optical coupler is connected to the output terminal of the second optical coupler. The first output terminal of the third optical coupler is sequentially connected to the first bandpass filter and the first photodetector to form a first detection optical path. The output terminal of the first photodetector is connected to the first input terminal of the second radio frequency power divider. The second output terminal of the third optical coupler is sequentially connected to the second bandpass filter, the second adjustable optical delay line, and the second photodetector to form a second detection optical path. The output terminal of the second photodetector is connected to the second input terminal of the second radio frequency power divider.

2. The radio frequency pulse width measurement device based on microwave photonics technology according to claim 1, characterized in that, The first radio frequency power divider divides the radio frequency pulse signal under test into two radio frequency signals with equal power and equal phase, which are loaded onto the amplitude modulator and the phase modulator respectively, to perform amplitude modulation on the first modulation optical path and phase modulation on the second modulation optical path respectively; the optical signal after amplitude modulation contains two optical sidebands with the same phase, and the optical signal after phase modulation contains two optical sidebands with a phase difference of 180°.

3. The radio frequency pulse width measurement device based on microwave photonics technology according to claim 2, characterized in that, The amplitude modulator and phase modulator can operate in either double-sideband modulation or carrier-suppressed modulation.

4. The radio frequency pulse width measurement device based on microwave photonics technology according to claim 2, characterized in that, The acousto-optic frequency shifter performs frequency shift modulation on the phase-modulated optical signal, and the first adjustable optical delay line delays the amplitude-modulated optical signal, keeping the optical path length of the optical signals on the first and second modulation optical paths consistent.

5. The radio frequency pulse width measurement device based on microwave photonics technology according to claim 4, characterized in that, The second optical coupler combines the first and second modulation optical paths to output a single optical signal, which includes an amplitude-modulated optical signal and a phase-modulated optical signal.

6. The radio frequency pulse width measurement device based on microwave photonics technology according to claim 5, characterized in that, The third optical coupler splits the single optical signal output from the combined output into two optical signals of equal power, which are then sent to the first detection optical path and the second detection optical path, respectively.

7. The radio frequency pulse width measurement device based on microwave photonics technology according to claim 6, characterized in that, The first bandpass filter and the second bandpass filter have opposite bandpass performance. When the first bandpass filter is an upper sideband filter, the second bandpass filter is a lower sideband filter; when the first bandpass filter is a lower sideband filter, the second bandpass filter is an upper sideband filter.

8. The radio frequency pulse width measurement device based on microwave photonics technology according to claim 7, characterized in that, The second adjustable optical delay line delays the filtered optical signal, and the first and second detection optical paths generate an optical delay difference. The first and second photodetectors beat to output low-frequency pulse signals. The frequency of the low-frequency pulse signals is the frequency shift amount of the acousto-optic frequency shifter. The low-frequency pulse signals output by the first and second photodetectors have a phase difference of 180° and a delay difference in pulse timing. The delay difference is adjusted by the second adjustable optical delay line.

9. The radio frequency pulse width measurement device based on microwave photonics technology according to claim 8, characterized in that, The second RF power divider combines the first and second detection optical paths to output a single RF pulse signal. The pulse duration of the RF pulse signal under test is obtained by low-rate acquisition and counting.

10. The radio frequency pulse width measurement method based on microwave photonics technology according to any one of claims 1-9, characterized in that, Includes the following steps: S100. The laser signal output by the laser is used as the optical carrier signal. The first optical coupler splits the optical carrier signal into two optical signals with equal power, which are then sent to the first modulation optical path and the second modulation optical path, respectively. S200, the first radio frequency power divider divides the radio frequency pulse signal under test into two radio frequency signals with equal power and equal phase, which are loaded onto the amplitude modulator and the phase modulator respectively, to perform amplitude modulation on the first modulation optical path and phase modulation on the second modulation optical path respectively; S300, the acousto-optic frequency shifter performs frequency shift modulation on the phase-modulated optical signal, and the first adjustable optical delay line delays the amplitude-modulated optical signal, keeping the optical path length of the optical signals on the first and second modulation optical paths consistent. S400 and the second optical coupler combine the first and second modulation optical paths to output a single optical signal, so that the single optical signal output by the modulation unit includes an amplitude-modulated optical signal and a phase-modulated optical signal. S500 and the third optical coupler split the single optical signal output from the combined output into two optical signals of equal power, which are then sent to the first and second detection optical paths, respectively. The first and second bandpass filters filter the optical signals. When the first bandpass filter allows the upper sideband of the optical signal to pass, the second bandpass filter allows the lower sideband of the optical signal to pass. S600 and the second adjustable optical delay line delay the filtered optical signal, the first detection optical path and the second detection optical path generate an optical delay difference, and the first photodetector and the second photodetector beat frequency to output a low frequency pulse signal; The S700 and the second RF power divider combine the first and second detection optical paths to output a single RF pulse signal. The pulse time width of the RF pulse signal under test is obtained by low-rate acquisition and counting.

Images