Abstract: A frequency-shift symmetric chirp spread spectrum modulation and demodulation method for interstellar communication links. The transmission process includes several steps: serial-to-parallel conversion, index addition, Gray coding, binary-to-decimal conversion, and frequency-shift symmetric chirp spread spectrum modulation. On the other hand, the reception process comprises demodulation of the symmetric chirp signal, fast Fourier transform, peak retrieval, decimal-to-binary conversion, Gray decoding, index removal, and parallel-to-serial conversion. The frame structure includes a preamble code, synchronization word, and user data. The symmetric chirp signal includes a pair of chirp signals with opposite polarities, ensuring the continuity of phase and frequency during the signal concatenation process.

Abstract: A distributed multi-antenna collaborative phase stabilization device for future broadband wireless communication. The device includes a central station and various antenna terminals interconnected via optical fibers to form a linear communication system. The distributed multi-antenna reception signals are optically modulated at the antenna terminals into different wavelengths of optical signals, and then coupled into a single optical fiber using wavelength division multiplexing technology for transmission to the central station. At the central station, the optical signals are converted back into the original RF (radio frequency) signals through optoelectronic conversion.

Abstract: A device for generating laser with ultra-narrow-linewidth includes an optical self-injection locking loop and an ultra-stable cavity phase-locked loop. The optical self-injection locking loop improves the quality factor of the laser resonator to narrow the linewidth. The ultra-stable cavity phase-locked loop locks the phase of the optical signal in the optical self-injection, synchronizing the laser frequency with the optical resonator. Through feedback control of the laser's driving current, it further reduces the laser's frequency noise and enhances the linewidth narrowing rate. Additionally, the ultra-stable cavity phase-locked loop provides stable control of the laser frequency, preventing mode hopping caused by laser frequency drift, thereby improving system stability. Therefore, this device can provide a stable narrow-linewidth laser source for applications in fiber optic communication, lidar, industrial device processing, and medical fields.

Abstract: A method and a device for testing linear deviation in high-speed frequency-modulated (FM) signals. The to-be-tested high-speed FM signal is modulated onto the optical domain by a high-speed electro-optic modulator. The optical signal is then split into two paths with differential delays using a high-speed tunable optical delay line, and mixed in the optical domain for detection. After filtering out the down-converted signal and low-frequency signal generated by the direct digital synthesizer (DDS), the phase detection is performed. The high-speed analog-to-digital converter (ADC) is used for data acquisition, reception, and analysis. By changing the delay of the high-speed tunable optical delay line and the frequency of the low-frequency signal generated by DDS, and conducting multiple measurements, polynomial fitting is applied to the sampled data to obtain the linear deviation of the high-speed FM signal under test.

Abstract: A device for radar target feature recognition based on optical time-delay fast interference scanning. The device includes an antenna unit, an electro-optical converter, an optical time-delay numerical control scanning device, an optical combiner, a photoelectric detector and a power characteristic analysis device. The device quickly scans the delay amount of the two signals through the optical delay line, and calculates the power of the combined signal through photoelectric conversion and linear power detection. By observing the relationship between the combined power and the delay time, the rapid identification of the target radar signal characteristics is realized.

Abstract: A transfer impedance calibration device for transducers based on spatial frequency domain smoothing technology is provided. The calibration device comprises a signal transmitter, a power amplifier, a transducer pair, a measurement amplifier, a signal collector, a measurement processor and a current sampler. The device extracts acoustic channel information through the sound filed spatial information or measurement method to design a spatial domain smoothing filter, and then comprehensively processes the transmitted current signal and the received signal through the spatial frequency domain smoothing technology to obtain the transfer impedance of the transducer pair.

Abstract: A broadband radio frequency signal optical fiber phase-stable transmission system includes a local end and a remote end connected by a dispersion compensation module and an optical fiber. The local end modulates a first auxiliary signal whose frequency is half of the frequency of the to-be-transmitted signal and a second auxiliary signal whose frequency is 1.5 times the frequency of the to-be-transmitted signal through the optical carrier and filters out a lower sideband to obtain an optical signal containing only the optical carrier, a first signal, and a second signal corresponds to the optical signal of the first-order upper sideband. The optical signal is transmitted to the remote end through the dispersion compensation module and the optical fiber.

Abstract: The present application provides a cover body mechanism, wherein the cover body mechanism comprises a first cover body, a handle, a second cover body, a connecting base and a sealing ring, wherein a bottom of the first cover body is provided with a groove; wherein the connecting end is movably accommodated in the groove through the second channel opening and connected with the groove through a second rotating shaft; wherein the connecting ring is sleeved with an upper side of the second cover body, an upper end of the connecting arm is movably accommodated in the groove through the first channel opening and is connected with the connecting end through a first rotating shaft; wherein the sealing ring is capable of deforming outward and expanding with the rise of the second cover body, so as to be sealingly contact to an inner side wall of a storage cavity in the sealed tank body.

Abstract: The invention discloses a fast measurement apparatus for optical link delay based on optical mixing and delay quantization. The apparatus uses a high-stability reference source to generate intermediate frequency signal and local oscillator signal, and obtains optical domain radio frequency signals through photon mixing, so as to use for the measurement of optical link delay. After the test signal passes through the link to be tested and the reference link, and then is mixed in the electrical domain, the delay amount information is transmitted to the intermediate frequency, and the influence of port impedance mismatch is eliminated. By rapidly changing the frequency of a series of signals, and quickly detecting the phase and quantifying the delay of the returned intermediate frequency signal, the fast measurement of the optical link delay is realized.

Abstract: A device for generating wide capture range frequency tunable optical millimeter-wave signal includes a millimeter-wave signal generating structure, a millimeter-wave signal modulation structure, an optical delay phase detection structure and a feedback control loop. The millimeter-wave signal generating structure obtains millimeter-wave signal by beat frequency of the optical signal generated by a master laser and a slave laser, the millimeter-wave signal is modulated onto an optical carrier of the master laser by the electro-optical modulation structure, and then passes through the optical delay phase detection structure to generate an error signal associated with a frequency of the millimeter-wave signal. The error signal is controlled by the feedback control loop to change temperature and driving current of the slave laser, and adjust a difference between output wavelengths of the master laser and the slave laser, and at last maintain the frequency and phase of the millimeter-wave be stable.

Abstract: The device of the disclosure provides an optical frequency comb frequency multiplication link to generate millimeter wave signals. The device of the disclosure also provides a local oscillator and a delay compensation link to eliminate the influence of the phase noise of the local oscillator on the test system. The local oscillator signal is down-converted in the optical carrier radio frequency link to obtain an intermediate frequency signal. The intermediate frequency signal is then down-converted with the local oscillator signal and the millimeter wave signal twice to cancel the influence of the microwave mixer noise on the test system. At last, by detecting the output low-frequency signal noise, the ultra-low phase noise level of the millimeter wave signal can be accurately obtained.

Abstract: A method of free-field broadband calibration of hydrophone sensitivity based on pink noise, relating to the field of free-field underwater acoustic measurement, and is mainly used for broadband measurements of hydrophone sensitivity in free-field. The method of the present disclosure is to transmit a broadband pink noise signal by controlling the signal source, and to perform the synchronous processing and FFT to the transmitted current signal and the received voltage signal, such as interception and zero padding, and finally obtain the transfer function in the frequency domain; by analyzing the direct wave and the reflected wave in the water tank, the transfer function is averaged by a rectangular window to eliminate the influence of the reverberation of the reflected wave in the water tank, so as to obtain the broadband transfer function of the free-field between the transmitting transducer and the hydrophone.

Abstract: Provided is a miniature magneto-optical fiber switch. The miniature magneto-optical fiber switch includes a miniature three-fiber collimator, a miniature current coil, and a miniature space optical processing optical core. The miniature magneto-optical optical fiber switch realizes a 1×2 optical fiber switch structure and a 2×1 optical fiber switch structure by controlling the current direction of the coil.

Abstract: A frequency modulation demodulator based on fiber grating sensor array comprises: a laser, radio frequency signal source, acousto-optic modulator, delay fiber pair, Mach-Zehnder modulator, optical filter, optical amplifier, optical isolator, circulator, fiber grating sensor array, photodetector and data acquisition card. By the cooperation of delay fiber pair and the fiber grating, the reflected optical pulses of the two gratings (the front grating and the back grating) are overlapped in the time domain to form interference, and thereby achieving multi-point array interference demodulation.

Abstract: A measurement device for polarization-maintaining optical fiber spindle difference delay is provided. The measurement device comprises a polarization-maintaining fiber (PM) Sagnac interferometer, a signal generator, a microwave detector, a microprocessor. The PM Sagnac interferometer comprises a laser, a photoelectric modulator, and a PM fiber coupler that are connected in sequence. The PM Sagnac interferometer further comprises an optical fiber interface J1 and an optical fiber interface J2 arranged at the two output ends of the PM fiber coupler, a PM fiber to be measured located between the fiber interface J1 and the fiber interface J2, and a photodetector arranged at the other output end of the PM fiber coupler.

Abstract: A measurement device for polarization-maintaining optical fiber spindle difference delay is provided. The measurement device comprises a polarization-maintaining fiber (PM) Sagnac interferometer, a signal generator, a microwave detector, a microprocessor. The PM Sagnac interferometer comprises a laser, a photoelectric modulator, and a PM fiber coupler that are connected in sequence. The PM Sagnac interferometer further comprises an optical fiber interface J1 and an optical fiber interface J2 arranged at the two output ends of the PM fiber coupler, a PM fiber to be measured located between the fiber interface J1 and the fiber interface J2, and a photodetector arranged at the other output end of the PM fiber coupler.

Abstract: A frequency chirp correction method for the photonic time-stretch system comprises acquiring the stretching signal, i.e. acquiring the time-domain data after the time-domain stretching. First, the time-domain data of the stretching signal is Fourier transformed to obtain the spectral distribution. The spectral distribution is then convoluted with the first frequency-domain correction factor, and then multiplied with the second frequency-domain correction factor to obtain the modified frequency spectrum. Finally, the modified frequency spectrum is performed by the inverse Fourier transform to obtain the time-domain signal after the frequency chirp correction.

Abstract: A frequency modulation demodulator based on fiber grating sensor array comprises: a laser, radio frequency signal source, acousto-optic modulator, delay fiber pair, Mach-Zehnder modulator, optical filter, optical amplifier, optical isolator, circulator, fiber grating sensor array, photodetector and data acquisition card. By the cooperation of delay fiber pair and the fiber grating, the reflected optical pulses of the two gratings (the front grating and the back grating) are overlapped in the time domain to form interference, and thereby achieving multi-point array interference demodulation.

Abstract: The present invention discloses a phenylate derivative, a preparation method therefor, and a pharmaceutical composition and uses thereof. Specifically, the invention relates to phenylate derivatives represented by formula (I), a pharmaceutically-acceptable salt thereof, a stereoisomer thereof, a preparation method therefor, a pharmaceutical composition containing the one or more compounds, and uses of the compounds in treating diseases related to PD-1/PD-L1 signal channels, such as cancers, infectious diseases and autoimmune diseases.

Abstract: A transfer impedance calibration device for transducers based on spatial frequency domain smoothing technology is provided. The calibration device comprises a signal transmitter, a power amplifier, a transducer pair, a measurement amplifier, a signal collector, a measurement processor and a current sampler. The device extracts acoustic channel information through the sound filed spatial information or measurement method to design a spatial domain smoothing filter, and then comprehensively processes the transmitted current signal and the received signal through the spatial frequency domain smoothing technology to obtain the transfer impedance of the transducer pair.