14 results about "Absolute frequency" patented technology

Ultra-Wideband (UWB) wireless technology transmits digital data as modulated coded impulses over a very wide frequency spectrum with very low power over a short distance. Accordingly, the inventors have established UWB devices which accommodate and adapt to inaccuracies, errors, or issues within the implemented electronics, hardware, firmware, and software. Beneficially, UWB receivers may accommodate offsets in absolute frequency between their frequency source and the transmitter, accommodate drift arising from phase locked loop and / or from relative clock frequency offsets of the remote transmitter and local receiver. UWB devices may also employ modulation coding schemes offering increased efficiency with respect to power, data bits per pulse transmitted, and enabled operation at higher output power whilst complying with regulatory emission requirements. Further, UWB devices may support a ranging function with range / accuracy not limited to the low frequency master clock employed within these devices enabling operation with ultra-low power consumption.

The invention discloses an ultra-narrow band optical filter absolute frequency reference in-situ calibration device which comprises a hollow cathode lamp, the output end of the hollow cathode lamp is connected with one input end of a one-to-two optical fiber through a light beam coupling device, and the output end of a variable diaphragm is connected with the other input end of the one-to-two optical fiber through an optical fiber; light beams output by the one-to-two optical fiber are split, the first split beam is input to the second photoelectric detector, and the second split beam transmits the ultra-narrow band light filter and is detected by the first photoelectric detector; the invention further discloses an in-situ calibration method for the absolute frequency reference of the ultra-narrow band light filter, the center transmission wavelength of the etalon is calibrated through the absolute wavelength of the hollow cathode lamp, the etalon is accurately controlled at constant temperature and constant voltage, the center transmission wavelength of the etalon is calibrated, and the calibration of the center wavelength of the etalon is integrated with an external optical signal detection function; and through the automatic calibration process, the calibration efficiency is greatly improved, manual operation errors are avoided, and a high-precision calibration task can be completed in a short time.

This invention discloses a closed-loop feedback structure and method for a fountain clock, relating to the field of time and frequency technology. The method includes: a crystal oscillator outputting a frequency signal; the frequency signal being divided into three frequency signals by a power distribution amplifier; the first frequency signal being used as a reference frequency for a microwave synthesis link to obtain the microwave frequency output by the microwave synthesis link; the microwave frequency signal being frequency-discriminated with the atomic transition probability of the fountain clock to obtain an error signal; the error signal being fed back to a phase transition meter as its input signal; the second frequency signal being mixed with the output signal of the phase transition meter; wherein, the frequency signal of an active hydrogen atomic clock is used as the reference signal for the phase transition meter; the mixed signal is transmitted to the crystal oscillator through a phase-locked loop; and the third frequency signal is used as the closed-loop feedback signal output of the fountain clock. This method achieves long-term output of a signal containing absolute frequency while improving the short-term stability of the fountain clock system's output signal.

The application provides a tunable laser multi-point absolute frequency locking device and method, and belongs to the technical field of lasers. The device comprises: a tunable laser unit provided with a frequency tuning port for receiving an external control signal; an interference measurement unit comprising a first beam splitter and an interference system; a frequency reference unit comprising a phase modulator, a gas absorption chamber and a photodetector arranged in sequence on the same optical axis; a locking and scanning control unit for identifying absorption peak characteristics according to an electrical signal, dynamically outputting a compensation signal to the frequency tuning port to realize frequency locking and control the interference system to perform interference measurement, or outputting a scanning signal to the frequency tuning port to control the tunable laser unit to perform frequency scanning. The application can obtain an interference signal with high contrast and high signal-to-noise ratio during measurement, is conducive to continuously and quickly locking multiple absolute frequency points on a wide spectrum, and greatly improves the efficiency, accuracy and application range of sweep frequency interference measurement.

The invention discloses an integrated Michelson optical frequency scale and displacement measurement system based on pyramid array feedback. The device comprises a Michelson optical frequency standard system (optical frequency standard system for short) and a Michelson displacement measurement system (displacement measurement system for short), and the optical frequency standard system and the displacement measurement system share the same reference arm. According to the invention, quantum spectral lines are used as absolute frequency reference to generate stable and accurate optical frequency standard signals, and the optical frequency standard signals are used as the reference of displacement measurement to realize organic unification of time frequency and displacement measurement; an optical frequency signal output by the optical frequency standard system has a relatively strong anti-interference capability to an external environment, and the resolution of the displacement measurement system can be improved; in order to solve the interference problem of the pitching inclination angle of a measuring arm cavity mirror in displacement measurement and tiny movement in the non-displacement measurement direction, the invention provides a reflecting mirror adopting an integrated pyramid array as a composite cavity, so that the stability and the robustness of a displacement measurement system can be improved, and the measurement range and the measurement resolution are optimized.

The application discloses a method and device for determining a synchronization signal block center frequency point, a storage medium and an electronic device. The method comprises the following steps: acquiring a target frequency band, wherein the target frequency band is a frequency band added in a new radio network; determining a target synchronization signal block frequency range matched with the target frequency band according to an absolute frequency point number of the target frequency band, a first correlation relationship and a second correlation relationship, wherein the first correlation relationship is a relationship between a synchronization signal block and a system bandwidth, and the second correlation relationship is a relationship between a control resource set and the system bandwidth; generating a synchronization signal block center frequency of the target frequency band according to the target synchronization signal block frequency range; and converting the synchronization signal block center frequency into a synchronization signal block center frequency point of the target frequency band. By using the above technical solution, the problem of low determination efficiency of the synchronization signal block center frequency point in the related art is solved.

The invention relates to the technical field of optical measurement, in particular to a device and method for improving the stability of a target laser beam, and the device comprises a target laser, a first modulator, a first PDH light path, a second modulator, a second PDH light path, a target FP cavity, a first monitor, a second monitor, a controller, and a third modulator. It can be known that a frequency stabilization mode that a traditional ultra-stable laser needs an external absolute frequency reference does not need to be adopted, a stable frequency difference is obtained through the structure of the ultra-stable laser, long-term drifting of feedback frequency is achieved through stable frequency difference characteristics and stable frequency difference change conditions, the structural complexity of the laser is reduced, and cost is reduced.

The invention relates to the technical field of optical measurement, in particular to a method and system for detecting the zero expansion temperature of an ultra-stable cavity. The method comprises the following steps: acquiring a first laser beam and a second laser beam; inputting the first laser beam into the target FP cavity from one end of the target FP cavity and inputting the second laser beam into the target FP cavity from the other end of the target FP cavity; the target zero expansion temperature is obtained according to the temperature related information of the target FP cavity, the frequency change degree of the second modulator is measured in the step of obtaining the target zero expansion temperature according to the temperature related information of the target FP cavity, and the target zero expansion temperature is obtained based on the frequency change degree of the second modulator; it can be known that compared with the prior art that only one absolute frequency reference is needed and only the frequency change degree of the second modulator is measured, the requirement for the absolute frequency stability of the laser is lowered, and meanwhile the zero-expansion temperature can be rapidly and simply obtained only by controlling the temperature and scanning the laser.

The invention belongs to the technical field of satellite precision measurement, and discloses an inter-satellite laser interference ranging frequency deviation calibration method and device, and the method comprises the steps: obtaining a double-satellite position vector, and carrying out the calculation to obtain an inter-satellite baseline vector; calculating according to the inter-satellite baseline vector to obtain an inter-satellite distance variation rate; obtaining an interference phase and an initial laser absolute frequency, and calculating to obtain an LRI instantaneous distance variation rate; according to the inter-satellite distance variability and the LRI instantaneous distance variability, calculating to obtain an LRI instantaneous variability scale factor; obtaining a daily scale factor value according to the LRI instantaneous variable rate scale factor; constructing a linear trend model according to the daily scale factor value and obtaining a scale factor observation value; iteratively calculating the scale factor observation value to obtain the iterated scale factor observation value; judging whether a convergence condition is met; and if yes, outputting the iterated scale factor observation value. The method can improve the calculation precision and efficiency of calculating the absolute frequency of the laser in the inter-satellite laser ranging by using the satellite orbit data.

This invention discloses an ultra-high stability laser system based on dual-path independent composite frequency stabilization and sum-frequency modulation, belonging to the field of precision laser spectroscopy and frequency control technology. The system includes two seed lasers (1560 nm and 1064 nm), a dual-wavelength common-cavity ultra-stable module, two acousto-optic frequency shift and dual-reference absolute frequency stabilization modules, and a nonlinear sum-frequency modulation (SFG) module. Full-time-scale frequency noise suppression is achieved through a three-stage cascaded closed loop consisting of a MHz fast loop, a kHz slow loop, and a Hz extremely slow loop. An acousto-optic modulator is placed in the sampling optical path fed into the ultra-stable cavity, and physical decoupling of the fast and slow loops is achieved through radio frequency bridging. The extremely low-frequency error signal detected by NICE-OHMS is fed back to the PPMgOLN crystal temperature or AOM driving frequency to compensate for the thermally induced drift of the nonlinear crystal. The system ultimately outputs a 633 nm laser power of not less than 50 mW, with a short-term frequency instability better than 5 × 10⁻⁶ mW. ‑15 @1 s.

The application provides a laser frequency stabilization system and method based on optical multi-frequency point cooperative locking, and relates to the technical fields of laser frequency stabilization and precision measurement. The system comprises a tunable laser unit, a multi-sideband modulation unit, an error signal generation unit and a feedback control unit. The multi-sideband modulation unit uses a controllable first radio frequency signal to modulate the phase of the laser to generate multiple sidebands; the error signal generation unit obtains a time domain electrical signal through frequency discrimination modulation. The feedback control unit calculates a total frequency discrimination error signal after the coherent superposition of multiple error signals, generates a feedback control signal according to the total frequency discrimination error signal and outputs the feedback control signal to the tunable laser unit to realize the locking of the center frequency of the laser. The application significantly improves the signal-to-noise ratio of the frequency discrimination signal through the cooperative action of multiple frequency points, can output an electrical absolute frequency signal anchored to the optical frequency reference interval while outputting high-stability frequency laser, and realizes the direct transfer of the optical domain frequency standard to the electrical domain.

The invention discloses a device for improving frequency stabilization precision of a cross-saturated absorption spectrum. The device comprises a single-frequency laser, a light splitting coupler, an optical frequency comb preparation system, an atom / molecule gas chamber, a frequency discrimination system and a servo system. According to the frequency stabilization system, a single-frequency laser is mainly used as a frequency stabilization object, after laser passes through a light splitting coupler, one light beam serves as output light, the other light beam enters an optical frequency comb preparation system, and the comb tooth frequency interval of the optical frequency comb is matched with the atomic excited state energy level frequency difference. The center frequency of the atom / molecule cross saturated absorption line provides absolute frequency reference; laser passing through the atom / molecule gas chamber carries cross saturation absorption spectrum signals, and error signals are obtained after the signals pass through the frequency discrimination system and fed back to the single-frequency laser through the servo system to achieve frequency stabilization. The comb tooth frequency interval of the optical frequency comb is matched with the atomic excited state energy level frequency difference, so that the interaction efficiency of laser and atoms / molecules is improved, a frequency stabilization error signal with higher precision is obtained, and the laser frequency stabilization performance is effectively improved.

The application discloses a kind of based on saturated absorption cavity ring-down spectroscopy of middle infrared laser frequency up-conversion 14 The application discloses a CO2 detection method and device. In view of the existing middle infrared direct detection heat noise, low signal-to-noise ratio of tail section of ring-down signal and other bottlenecks, the application adopts double QCL light sources, absolute frequency locking, saturated absorption cavity ring-down light cavity, frequency up-conversion detection and data processing module. By saturated absorption, Doppler broadening is eliminated, and by using sum frequency effect, 4.5 μm middle infrared ring-down signal is converted into 861 nm near infrared sum frequency light, which is received by a low-noise silicon-based detector, so that the signal-to-noise ratio of weak ring-down signal is significantly improved. In combination with double optical beat frequency technology, laser frequency absolute locking is realized. The device can obtain MHz-level narrow linewidth absorption, effectively suppresses isotope cross interference, and has a limit detection sensitivity of ppq order of magnitude, and has the advantages of small size, low cost and on-site detection.

The invention discloses an optical clock absolute frequency traceability device and method based on photo-generated microwaves, and belongs to the technical field of time frequency, the optical clock absolute frequency traceability device locks the repetition frequency of an optical comb on an optical clock on the basis of the photo-generated microwaves, and then a microwave signal controlled by the optical clock is obtained through detection of a photoelectric detector; and the signal is directly compared with a local oscillation signal controlled by the cesium fountain clock for beat frequency measurement, so that the problem that the traceability precision is reduced when a hydrogen clock is used as a flywheel clock can be solved. Compared with the prior art, the scheme of a flywheel clock is not used any more, the optical clock and a reference clock cesium fountain clock are used for direct frequency comparison, the short-term stability index of measurement is improved, the measurement duration of the frequency of the optical clock is shortened, the optical clock can complete frequency tracing in a shorter time, the measurement efficiency and usability of the optical clock are improved, and the measurement cost is reduced. And the optical clock can be more quickly verified and popularized as a new second definition device, so that the development of the time frequency standard is promoted.