811 results about "Atomic clock" patented technology

Disclosed herein is a system for rapidly resolving position with centimeter-level accuracy for a mobile or stationary receiver [4]. This is achieved by estimating a set of parameters that are related to the integer cycle ambiguities which arise in tracking the carrier phase of satellite downlinks [5,6]. In the preferred embodiment, the technique involves a navigation receiver [4] simultaneously tracking transmissions [6] from Low Earth Orbit Satellites (LEOS) [2] together with transmissions [5] from GPS navigation satellites [1]. The rapid change in the line-of-sight vectors from the receiver [4] to the LEO signal sources [2], due to the orbital motion of the LEOS, enables the resolution with integrity of the integer cycle ambiguities of the GPS signals [5] as well as parameters related to the integer cycle ambiguity on the LEOS signals [6]. These parameters, once identified, enable real-time centimeter-level positioning of the receiver [4]. In order to achieve high-precision position estimates without the use of specialized electronics such as atomic clocks, the technique accounts for instabilities in the crystal oscillators driving the satellite transmitters, as well as those in the reference [3] and user [4] receivers. In addition, the algorithm accommodates as well as to LEOS that receive signals from ground-based transmitters, then re-transmit frequency-converted signals to the ground.

A method of fabricating compact alkali vapor filled cells that have volumes of 1 cm³ or less that are useful in atomic frequency reference devices such as atomic clocks. According to one embodiment the alkali vapor filled cells are formed by sealing the ends of small hollow glass fibers. According to another embodiment the alkali vapor filled cells are formed by anodic bonding of glass plates to silicon wafers to seal the openings of holes formed in the silicon wafers. The anodic bonding method of fabricating the alkali vapor filled cells enables the production of semi-monolithic integrated physics packages of various designs.

The present invention provides a method and apparatus for making atomic clocks or atomic magnetometers as self-modulated laser systems based on the physics of push-pull optical pumping. An atomic vapor cell is required to be in the laser cavity. With proper conditions, spontaneous push-pull optical pumping can occur inside the laser cavity. This causes the laser beam to be modulated at hyperfine-resonance frequency. With a fast photodetector, the modulated laser signal can be converted into the electrical signal, which serves as the atomic clock ticking signal or magnetometer signal. The self-modulated laser system does not use any local oscillator and the microwave circuit to lock the oscillator frequency to the hyperfine-resonance frequency, and therefore can consume less power and become more compact than conventional systems. This invention will benefit applications of time measurements and magnetic-field measurements.

The invention relates to a time synchronization device in a radio navigation system, in particular to a high-precision time synchronization device, which solves the problems in the prior time synchronization device including long-time synchronization adjustment and inability of real-time monitoring and adjustment of clock signal. In the device of the invention, an industrial computer obtains phase difference signal output from a phase comparator via a GPIB bus, and respectively transmits a control signal to a synchronizer trigger, an atomic clock and a signal source via a RS232 serial communication bus; and the industrial computer further controls the operating state and the switching thereof. The operating state includes time synchronization state: the phase comparator obtains the phase difference of signals output from the synchronizer trigger and the atomic clock, and the industrial computer adjusts the signal output from the atomic clock to synchronize with the signal output from the synchronizer trigger; and monitoring state: the phase comparator obtains the phase difference of signals output from the atomic clock and the signal source, and the industrial computer adjusts the signal output from the signal source to synchronize with the signal output from the atomic clock.

An atomic clock having a physics package that includes a vacuum chamber cavity that holds atoms of Rb-87 under high vacuum conditions, an optical bench having a single laser light source, a local oscillator, a plurality of magnetic field coils, an antenna, at least one photo-detector and integrated control electronics. The single laser light source has a fold-retro-reflected design to create three retro-reflected optical beams that cross at 90° angles relative to one another in the vacuum chamber cavity. This design allows the single laser light source to make the required six trapping beams needed to trap and cool the atoms of Rb-87. The foregoing design makes possible atomic clocks having reduced size and power consumption and capable of maintaining an ultra-high vacuum without active pumping.

A system is provided for rapidly ascertaining the position of a pulse train emitter such as a radar using multiple collectors without requiring more than one platform to measure the same pulse. Thus time-of-arrival measurements at a number of collecting platforms are performed, with the positions of the platforms being accurately ascertainable using GPS data, and with time synchronization between the spaced-apart collectors performed by utilizing atomic clocks. In the multi-ship case, geolocation can be performed on ten milliseconds of data as opposed to 30 seconds of data for measurements involving a single platform. The subject system is preferable to conventional time-difference-of-arrival geolocation systems because those systems require that each of the collecting platforms measure the same pulse from the emitter, which severely constrains the flight paths of the collectors, limits the amount of usable data, and increases the system's sensitivity requirements.

A data acquisition system includes multiple terminal nodes. Each terminal node includes a sensor, an atomic clock and a controller. Each sensor is adapted to sense an external event and transform the external event into an electrical signal. Each atomic clock generates a time reference. Each controller is coupled to the atomic clock and the sensor, and is configured to merge the electrical signal with the time reference and provide a time-stamped data stream to a remote central processor. The remote central processor is configured to organize a respective time-stamped data stream from one terminal node with another respective time-stamped data stream from another terminal node.

The present invention provides a method and system to simultaneously use the microwave and Zeeman end resonances associated with the same sublevel of maximum (or minimum) azimuthal quantum number m to lock both the atomic clock frequency and the magnetic field to definite values. This eliminates the concern about the field dependence of the end-resonance frequency. In an embodiment of the system of the present invention, alkali metal vapor is pumped with circularly-polarized D₁ laser light that is intensity-modulated at appropriate resonance frequencies, thereby providing coherent population trapping (CPT) resonances. In another embodiment, pumping with constant-intensity circularly-polarized D₁ laser light enhances magnetic resonances that are excited by alternating magnetic fields oscillating at appropriate resonance frequencies. In both embodiments, the resonances are greatly enhanced by concentrating most of the atoms in the initial state of the resonances, and by diminishing the spin-exchange broadening of the resonances. This leads to greater stability of optically pumped atomic clocks. This invention can also be used to operate an atomic magnetometer, where the feedback signal used to stabilize the magnetic field at the alkali-vapor cell can serve as a sensitive measure of the ambient magnetic field.

The present invention enables the manufacture of an NTP stratum-1 server using IS-95/2000 synchronous mobile terminals as an external reference clock, instead of an expensive atomic clock or a GPS receiver having a difficulty in indoor reception. It is therefore possible to use an NTP server that provides precise time information by a relatively inexpensive method so as to synchronize a subnet or Internet. By using the NTP servers, precise UTC information and a tick rate stable in the system operation can be provided to the nodes of a network.

The invention provides spectroscopy apparatuses and methods allowing precise overlapping between circularly polarized pump beam and a counter propagating linearly polarized probe beams in a sample which presents unique advantages for precision spectroscopy. In general, the apparatus comprises a phase retarding element with which by double pass by retro reflection of an incident beam turn linearly polarized light to circular and vice versa. This unique configuration enable to design a compact and miniature apparatus which may be applied for measuring polarization spectroscopy, nonlinear optical rotation and coherent population trapping phenomena with certain advantages resulting from the unique optical arrangement. The design of the apparatus further facilitates integration and scaling to produce arrays of units which may be particularly useful for magnetometry applications. Other important applications of the invention include laser frequency stabilization and atomic clocks.

A microfabricated atomic clock (mfac) or magnetometer (mfam) vapor cell utilizing a method of forming a self-condensing silicon vapor cell cavity structure for the atomic clock or magnetometer.

The invention relates to a precise orbit determination method of a navigation satellite for assisting a clock error between stations, which is characterized by comprising the following steps: configuring an atomic clock and a nanosecond stage time synchronization system at each station of an area network, receiving a distance measurement signal of a navigation satellite by each station of the area network to obtain the carrier phase data of each station, detecting the periodic trip generation moment of the carrier phase data by a Blewitt method and carrying out time synchronization between the stations by a two-way satellite time frequency transmission method TWSTFT to obtain a clock error between the stations; resolving a differential equation under an inertial coordinate system to obtain an orbit of the navigation satellite. Before orbit determination data are processed, the method firstly realizes the time synchronization between the stations with high accuracy (i.e.: obtaining the clock error between the stations). During the processing of the orbit determination data, an improved non-error method is adopted, only the orbit needs to be resolved, and the clock error between the stations does not need to be resolved, which not only can improve geometrical factors but also is beneficial to separating a system error (the clock error between the stations). Thus, the orbit determination accuracy can be enhanced.

The invention discloses an MEMS atom cavity chip and a preparation method thereof. The chip comprises two glass substrates and a silicon substrate, heater strips and radio-frequency coils are integrated on the glass substrates, metal leads connecting front faces and reverse faces are processed by laser perforation and plating technology. Atom cavity spaces and thermal insolating rings are integrated on the silicon substrate. The injection of alkalis is finished in an anaerobic box, the injection and bonding of air is finished then, and the injection of high concentration supplementary air is realized. The invention has high integrated level, and realizes on-chip integration of the heater strip, the radio-frequency coil and thermal isolating ring structures. The invention can be used for MEMS atomic gyroscopes besides MEMS atomic clocks and MEMS atom magnetometers.

The invention discloses an obtaining method of atomic clock reference frequency and atomic clock thereof. The method includes the following steps: a semiconductor laser is driven by a drive current source, and the semiconductor laser is modulated by microwave signals simultaneously; two pumping lasers with same frequency difference and modulating frequency of microwave signals can be generated; the two pumping lasers act on atoms having an Lambda three-level system; when the frequency of microwave signals has deviation with the interval of two lower levels of the Lambda three-level system of the atoms and when the frequency deviation is bigger than spectral half width of coherent population tripping (CPT), a relaxation oscillator signal with the same frequency as CPT detuning transient oscillation is generated; and the frequency of the relaxation oscillator signal is added with the modulating frequency of the microwave signals so as to obtain standard frequency of an atomic clock. The atomic clock designed according to the method has simple structure and omits a locking circuit of the traditional atomic clock, thereby improving the adaptability for the external environment.

The invention relates to a device and a method for continuously measuring the arrival time of a photon sequence. The device comprises a single photon detector, a preamplifier, a constant ratio discriminator, an atomic clock, a counter, a time-to-digital converter, a controller, a memory unit and a computer, wherein the output end of the constant ratio discriminator is connected with the controller; a square-wave pulse output by the atomic clock is used as a counting object of the counter and is transmitted into the time-to-digital converter; the rising edge of the square-wave pulse is used as a start signal of the time-to-digital converter, and the rising edge of a digital pulse signal is used as a stop signal of the time-to-digital converter; and the control end of the controller is respectively connected with the counter, a digit converter and the memory unit and used for controlling the synchronous storage of rough measuring time and fine measuring time into the memory unit. The invention solves the technical problems of continuous measurement incapability, narrow measurement range and limited application range of a traditional photon sequence arrival time measuring device, and the device has a wide measurement range and high accuracy in measuring the photon arrival time.

The invention relates to a micro electro mechanical system (MEMS) manufacturing process-based micro atomic cavity air tightness package structure and a method. The structure and the method are characterized in that: a micro atomic cavity which is manufactured by the MEMS process is arranged in a glass or metal seal buffer cavity through a supporting structure, and the air tightness of the micro atomic cavity is improved, so that the service life of devices such as a micro atomic clock and the like based on the micro atomic cavity is prolonged, and the stability of the devices is improved. The structure and the method have a key point that: in the glass or metal buffer cavity structure, the inside of the buffer cavity is vacuumized or filled with buffer gas of which the components and the pressure are approximate to those of gas in the micro atomic cavity, and a leading wire of the micro atomic cavity passes through the buffer cavity to realize air tightness lead. By the package structure and the method, the leakage rate of the micro atomic cavity and outside can be effectively reduced, and the technical problem of short service life of micro atomic cavity devices is solved. The air tightness package structure is particularly suitable for the micro atomic cavity devices such as micro atomic clocks, micro atom magnetometers, micro atom gyroscopes and the like with low power consumption and small volumes.

The invention relates to an underwater sound array system without cable connection in deepwater and a synchronous acquisition method. The synchronous acquisition method is used for long-term synchronous data acquisition for array elements of underwater sound array in the deepwater. The method comprises a synchronization method and a data acquisition recording method. The synchronization method comprises the steps of: 101) timing the array elements; and 102) keeping the time continuously by high-precision clock sources contained inside the array elements, thereby realizing long-term accurate synchronization among the array elements. The step 101) can adopt PPS signals provided by a GPS system or a Beidou system to accomplish timing. The clock source can adopt a miniature CPT atomic clock. According to the invention, a strategy for carrying out synchronization by adopting synchronization signal wires in a cable in the prior art is omitted among the array elements, and a mode of cooperating timing with time keeping is adopted to realize synchronization of the array elements. In addition, introduction of the synchronization mode enables the array elements to be arranged flexibly and can integrate functions of data acquisition and recording.

A transponder satellite communication navigation positioning system relates to the field of space technology. The system is equipped with a high-precision atomic clock at a ground communication navigation reference station, and the satellite orbit data is given by the satellite orbit determination system; the satellite integrity is given by the monitoring system The data forms the navigation message, and the ranging code composed of pseudo-random codes forms an integrated baseband signal, which is modulated by spread spectrum to form a navigation signal carrier, which is transmitted through the antenna and forwarded by 3 to 9 satellites in a certain geometric distribution in space The device converts the frequency and forwards the downlink, and broadcasts the signal to the coverage area; the ground user terminal receiving device receives the navigation signal carrier, and despreads and demodulates it to obtain the navigation data, thereby determining the position, speed and time of the user terminal receiving device. The invention has the advantages of low investment, guaranteed accuracy, convenient and flexible system maintenance and management, and dual functions of navigation and communication, so that the navigation and positioning accuracy can reach meter-level precision or be better than meter-level precision.

The invention discloses a device for achieving a minitype CPT atomic clock physical system. The device comprises a Bias-Tee, a VCSEL, a first quarter wave plate, an atomic gas chamber, a second quarter wave plate, a polarization beam splitter, a first photoelectric detector and a second photoelectric detector. The invention further discloses a method for achieving the minitype CPT atomic clock physical system. Elliptically-polarized light is adopted for resonance with atom CPT, and difference detection is conducted on the optical rotation effect generated by the resonance. According to the device and method for achieving the minitype CPT atomic clock physical system, background noise generated by optical frequency components which do not interact with atoms in multi-color light output by the VCSEL and conversion noise generated by light interacting with the atoms due to light frequency jitter which is converted into signal amplitude jitter through action with the atoms are eliminated, and the signal to noise ratio of CPT resonance signals is greatly increased; in addition, the device and the method further have the advantages that the influence on the obtained CPT resonance signals by environment magnetic field intensity fluctuation is small, and laser frequency stabilization can be easily achieved through an achieved atomic clock.

The invention discloses a high-precision fiber frequency transmission system, and the system comprises a PID circuit board, a phase discriminator, a photoelectric detector, a Faraday rotary reflector, a microwave photon phase shifter, a 2*2 optical coupler, a circulator, a slave laser, a frequency reference signal source, a main laser emitter, an isolator, an optical fiber link, and a time frequency receiving and transmitting module. On the basis of a single-fiber bidirectional return error signal obtaining mode, the system carries out the optical fiber link noise compensation based on injection locked coherent detection and the microwave photon phase shifter, thereby achieving the high-precision fiber frequency transmission. The system can achieve the high-precision recovery of a frequency reference signal of a local end at a far end. The system can achieve the two features, needed by phase change, on the same microwave photon phase shifter at the same time: large-bandwidth response and large dynamic range, facilitates the reduction of the complexity, and improves the stability and adaptability. The system can be used in the fields of comparison of the optical clock/atomic clock and the frequency transmission.

The invention discloses a Beidou wide area timing system and method. The Beidou wide area timing method comprises the following steps: obtaining a phase observation value and a pseudo-range observation value of a China Beidou satellite navigation system of each ground Beidou tracking station network, time difference monitoring data of the time of the China Beidou satellite navigation system and the Beijing time of a laboratory atomic clock group, a satellite ephemeris of the China Beidou satellite navigation system, earth rotation and antenna phase center parameters; performing preprocessing of data check, gross error elimination and cycle slip detection on the obtained data; performing error model correction and fine data processing on the preprocessed data; encoding the corrected data togenerate a telegraph text, and uploading the telegraph text to a communication satellite for broadcasting; and performing, by a user, non-difference precise timing solution and time difference parameter correction on the received corrected data and the local observation data to obtain a user local time consistent with the standard time. By adoption of the Beidou wide area timing system and methoddisclosed by the invention, single-station wide area timing service can be achieved, the timing precision is high, the operability is high and the action range is limited.

A device for an atomic clock, including: a laser source (102) that generates a laser beam; a splitter (101) that makes it possible to divert and allow a portion of the laser beam to pass therethrough in accordance with a predefined percentage; a quarter-wave plate (105) that modifies the linear polarization of the laser beam into circular polarization and vice versa; a gas cell arranged on the circular polarization laser beam; a mirror (107) sending the laser beam back toward the gas cell (106); a first photodetector (108a), and a polarizer (103) arranged between the laser beam outlet and the splitter in order to protect the laser source from the retroreflections emitted by different optical elements constituting the device.

The invention relates to a coherent population trapping (CPT) atomic clock servo circuit, which comprises a microcontroller, wherein a signal input end of the microcontroller is connected with a photoelectric detector of an atomic clock physical unit; a signal output end of the microcontroller is connected with a laser of the atomic clock physical unit sequentially through a frequency signal output circuit and a frequency conversion stage circuit; the signal output end of the microcontroller is connected with the laser of the atomic clock physical unit through a constant current source circuit; and the signal input end and the signal output end of the microcontroller are connected with a temperature control circuit and a magnetic field monitoring circuit respectively. The CPT atomic clockservo circuit takes the microcontroller as a control core, is responsible for monitoring temperature and magnetic fields, controlling digital devices, performing phase sensitive detection, producing square wave modulation signals, and regulating and controlling constant current source current, and realizes the automatic scanning and locking control on laser frequency and microwave frequency. The CPT atomic clock servo circuit realizes small volume digitalization and handy control, simplifies the realization of circuits, reduces the possibility that signals are interfered, and is low in cost, high in stability and low in power consumption.

A micro-fabricated atomic clock structure is thermally insulated so that the atomic clock structure can operate with very little power in an environment where the external temperature can drop to −40° C., while at the same time maintaining the temperature required for the proper operation of the VCSEL and the gas within the vapor cell.