54 results about "Crystal oscillator frequencies" patented technology

The invention discloses a method for realizing TD-SCDMA base station synchronization, which is used for synchronizing a base station in the absence of GPS signal and includes that: step1, a GPS receiver receives a GPS satellite signal and transmits pulse per second signal to a synchronization module; the synchronization module adopts the pulse per second signal to measure the deviation value of work frequency and standard frequency of a crystal oscillator, and compute the frequency deviation compensation of the crystal oscillator; step 2, when the GPS receiver receives no GPS satellite signal, the GPS receiver informs the synchronization module; when the synchronization module is informed that the GPS receiver receives no GPS satellite signal, the synchronization module adopts frequency deviation compensation to compensate a frame timing signal generated by a clock signal of the crystal oscillator, and the frame timing signal is used for synchronizing the base station. The invention can eliminate phase deviation caused by the frequency deviation of the crystal oscillator and continuously accumulated with time, and enable the frame timing signal of the base station to be synchronous with frame timing signals of other base stations in longer time.

A method capable of detecting a status of a basic input/output system (BIOS) for setting a clock is applied to a clock generating device of a computer motherboard and sets the clock according to a signal status of the BIOS or a trigger signal. A device capable of detecting the BIOS status for setting the clock is also proposed. The device has a crystal oscillator, a frequency control unit, a phase-lock-loop (PLL) spread-spectrum unit electrically connected with the crystal oscillator and the frequency control unit, a memory unit having a clock setting value stored therein, a detection control unit electrically connected with the memory unit and used to detect a signal status, and a logic control unit electrically connected with the PLL spread-spectrum unit, the frequency control unit and the detection control unit.

A GPS receiver comprises a crystal oscillator with a manufacturer's characteristic curve, a GPS radio, a TCO temperature sensor, and a GPS receiver software. The crystal oscillator serves as a local reference oscillator for the GPS radio. The GPS receiver software instructs the GPS radio to search radio spectrum for GPS satellite transmissions. Once the combination locks onto a minimum number of GPS satellites and produces a user position fix, the precise crystal oscillator frequency can be measured and associated with a temperature reading from the TCO to software-compensate the local oscillator in later cold-start frequency searches. A “flat” SCXO model is piecemeal upgraded with individual calibrations as they are collected over the life of the GPS receiver. During manufacturing of the GPS receiver such flat-SCXO model begins as a device characteristic curve supplied by the crystal manufacturer.

The invention relates to a frequency calibration method, device and system for an oven controlled crystal oscillator. The method comprises the steps that preset test conditions are read and written in the crystal oscillator; output frequencies of the crystal oscillator under the different test conditions are read; least squares curve fitting is performed on relation arrays of the test conditions and the output frequencies to obtain polynomial functions about the test conditions and the output frequencies; the test condition corresponding to the calibration frequency of the crystal oscillator is calculated through the polynomial functions and is written in the crystal oscillator; the output calibration frequency of the crystal oscillator under the test condition corresponding to the calibration frequency is read and verified; if the output calibration frequency meets the range of frequency accuracy, calibration is over; or else, the calibration continues to be performed after coefficients of the polynomial functions are adjusted. According to the frequency calibration method, device and system, the frequency calibration of the oven controlled crystal oscillator can be automatically completed, measuring errors are reduced, and the purposes of performing frequency calibration automatically and accurately and enhancing production efficiency are achieved.

The temperature compensated timing signal generator comprises a crystal oscillator that generates a reference time signal, and a divider circuit that receives the reference time signal as input and outputs a coarse time unit signal, the coarse time unit signal having an actual frequency deviating from a desired frequency as a function of temperature of the crystal oscillator. The signal generator also includes a high frequency oscillator configured to generate an interpolation signal having a frequency greater than the frequency of the crystal oscillator. A finite state machine computes a deviation compensating signal as a function of temperature, the signal comprises an integer part representative of an integer number of pulses to be inhibited or injected in the divider circuit and a fractional part representative of how much the output of a new time unit signal pulse should further be delayed to compensate for any remaining deviation.

The invention is an all-optical Rb frequency standard method and system. The method: firstly, adjusting the pump laser to the wavelength corresponding to Rb D2 line; then modulating semiconductor laser by radio signal to produce optical component needed to excite coherent resonance, and using two proper side bands to excite Rb 0-0 ultrafine coherent resonant transition; when the frequency of fine crystal oscillator deviates, the atomic system outputs a deviation correcting signal to control VCO, to make the VCO return to original frequency. The system is composed of semiconductor laser diode, Rb atomic physical system, optical signal detecting and amplifying device and high-precision constant temperature VCO, which are linked with one another. It uses Rb atomic coherent resonant transition chart line to identify the frequency, and the frequency locking is higher; needs no mechanical exciting system, avoiding the effect of mechanical system; uses commercial fractional laser diode as excitation source.

Methods for compensating the existing crystal oscillator frequencies in extended temperature ranges. These are utilizing existing crystal oscillators on any system design which may have quartz crystals with associated circuitry to deliver frequency or timing reference signals. They are increasing these existing circuitry's accuracy simply by adding small integrated circuit component.

The temperature compensated timing signal generator comprises a crystal oscillator that generates a reference time signal, and a divider circuit that receives the reference time signal as input and outputs a coarse time unit signal, the coarse time unit signal having an actual frequency deviating from a desired frequency as a function of temperature of the crystal oscillator. The signal generator also includes a high frequency oscillator that generates an interpolation signal having a frequency greater than the frequency of the crystal oscillator. A finite state machine computes a deviation compensating signal as a function of the temperature signal, the signal comprises an integer part representative of an integer number of pulses to be inhibited or injected in the divider circuit and a fractional part representative of how much the output of a new time unit signal pulse should further be delayed to compensate for any remaining deviation.

The invention relates to a temperature compensation method used for simulating a temperature compensated crystal oscillator. The method includes the steps that a voltage temperature curve of an uncompensated crystal oscillator is measured; resistance temperature characteristics of a thermistor are measured and taken for reference; according to the voltage temperature curve of the uncompensated crystal oscillator and the resistance temperature characteristics of the thermistor, temperature compensation network parameter values are calculated and optimized; according to the calculated and optimized temperature compensation network parameter values, matched components are selected, and a temperature compensation network is constructed; temperature compensation is performed on the crystal oscillator through a temperature compensation network, and frequency temperature characteristics of the compensated crystal oscillator are measured. With the method, the temperature compensation effect of the temperature compensated crystal oscillator is effectively improved, particularly, the temperature compensation effect in a wide working temperature range is improved, the first time success rate of temperature compensation and the reliability of the temperature compensated crystal oscillator are improved, the production cost and the adjusting complexity of the temperature compensated crystal oscillator are reduced, and the production efficiency is improved.

The invention provides an energy conservation time synchronization method of a wireless temperature detecting net. The energy conservation time synchronization method comprises that step one, a master node relative synchronization computation table is created; step two, a slave node relative synchronization computation table is created; and step three, time synchronization operation of a master node and slave nodes is achieved. According to the energy conservation time synchronization method, on one hand, network node clock errors caused by the aging rate of a crystal oscillator are eliminated, on the other hand, network node clock errors caused by the frequency error of the crystal oscillator are eliminated, meanwhile network repeat synchronization is reduced as far as possible on the basis that network reliable synchronization is guaranteed, synchronization precision is improved, synchronization efficiency is also improved, robustness of a network is improved, and the energy conservation time synchronization method is high in precision, low in power consumption, convenient to use, fast, and capable of being suitable for the wireless temperature detecting net.

The invention discloses a 27MHz crystal oscillator frequency synthesizer used for millimeter wave wireless communication and belongs to a Q waveband high-speed short-distance wireless communication system in a wireless personal area network (WPAN). The 27MHz crystal oscillator frequency synthesizer comprises a 27MHz crystal oscillator, a frequency discrimination and phase discrimination device, a charge pump, a low-pass filter, a quadrature voltage-controlled oscillator, a divide-by-2 frequency divider, a divide-by-5 frequency divider and a divide-by-163/164/165/167/168/169/171/172/173 multimode frequency divider. When the frequency dividing ratio of the multimode frequency divider is changed, the input reference frequency is not changed so that the voltage-controlled oscillator outputs Q waveband local oscillator signals with different frequencies, and local oscillator signals with different frequency points can be achieved in the multimode frequency divider.

The invention discloses a 1:1 structural 27MHz crystal oscillator frequency synthesizer for 60GHz wireless communication. The frequency synthesizer adopts a phase-locked loop structure based on integer frequency division, and the phase-locked loop structure based on integer frequency division adopts a 27MHz crystal oscillator frequency as the reference frequency of a phase frequency detector (PFD), and the frequency dividing ratio is controlled by a dividing 64 to 127 multimode frequency divider, the frequency dividing ratio of the multimode frequency divider is determined by 2<6>+2<5>P5+2<4>P4+2<3>P3+2<2>P2+2P1+P0, and the frequency division of all the integers between 64 and 127 can be achieved by changing high-low electrical levels from P0 to P5. By utilization of the 1:1 structural 27MHz crystal oscillator frequency synthesizer for 60GHz wireless communication disclosed by the invention, a frequency synthesizer structure suitable for the 60GHz frequency spectrum planning in China is designed, and therefore, the frequency synthesizer can be used for a double-conversion transceiver with a ratio of 1: 1.

A digital phase-locked ring to regulate frequency of crystal oscillator includes LIU, PD, DIV, DLF and OCXO, of which DLF consists of two first-in and first-out shift counters of FIFO, and FIFO2, accumulator ACC, mutiplying-dividing circuit and D/A converter. The method of realization for it is as follows: 1) phase error data sampling, 2) phase error data to be formed to be one-dimensional digital set {delta phi}m and to input them into FIFO, and FIFO2 as well as to get rid of a phase error data being sampled at the most early time, 3) accumulating phase error data delta phi and then to carryon averaging to calculate out the corresponding voltage controlled voltage value and 4) to regulate OCXO output frequency through D/A.

The invention discloses a frequency monitoring system and a frequency monitoring method for a crystal oscillator. The system comprises a main control unit. The main control unit is connected with a frequency counting unit, a temperature changing unit and a power supply unit. The frequency counting unit is connected with a test unit. The main control unit is used for outputting control parameters to all connection equipment. The temperature changing unit is used for providing a temperature changing condition for a to-be-monitored oscillator under the control of test temperature cycling parameters output by the main control unit. The power supply unit is used for providing a test voltage for the test unit. The test unit is used for monitoring the frequency of the to-be-monitored oscillator in the temperature changing condition. The frequency counting unit is used for detecting the real-time frequency parameters of the to-be-monitored oscillator in the test unit and feeding back the real-time frequency parameters to the main control unit. The main control unit calculates the jump amount of the frequency. When the jump amount of the frequency reaches a limit value, the frequency counting unit is triggered to count the frequency. Therefore, the continuous frequency monitoring of the crystal oscillator in the temperature changing condition is realized.

The invention discloses an automatic aging test system for a constant-temperature crystal oscillator. The automatic aging test system comprises an aging test box, a control computer, a frequency counter and a rubidium atomic clock, the aging test box body is internally provided with a thermal insulation layer, the working environment temperature of test equipment can be reduced, the service life of the test equipment is prolonged, the working environment temperature of the constant-temperature crystal oscillator can be increased, the working current is reduced, and the test cost is saved; andthe aging test box is internally provided with a plurality of main test circuit boards and a plurality of auxiliary test circuit boards. Each main test circuit board comprises a constant temperature crystal oscillator and a frequency transmission circuit. Each auxiliary test circuit board comprises a frequency transmission circuit, a voltage protection circuit, a switching power supply voltage regulation circuit, a voltage-controlled voltage circuit and a communication level conversion circuit. The testing system disclosed by the invention can automatically acquire frequency data of the large-scale constant-temperature crystal oscillator, automatically adjust and test power supply voltage, realize overvoltage protection of the power supply voltage, automatically adjust the voltage-controlled voltage, and realize automatic timing startup and shutdown of the constant-temperature crystal oscillator and the like.

The method concerns the reliable start-up of a crystal oscillator where the drive levels the crystal is subjected to are kept low in order to avoid over-driving the crystal. After applying a start-up value (12) of a parameter controlling the drive level where the drive level associated with the start-up value is rather high such that reliable start-up is ensured the parameter is modified step-wise so as to reduce the drive level until the crystal oscillator ceases to operate regularly (17, 18). To assess whether this is the case, the frequency of the crystal oscillator is compared with the frequency of an auxiliary oscillator. A safety margin is added to the parameter and the result stored in a non-volatile memory as an operating value (19). The crystal oscillator is then restarted with the start-up value (13) and after a delay the operating value is applied (14). The start-up value can be determined using an initial value for the parameter which is associated with a moderate drive level and where necessary modifying the parameter step-wise, increasing the drive level until the oscillator starts up. The start-up value so determined is also stored in the non-volatile memory. In subsequent start-ups the stored start-up value and operating value can be applied immediately.

The invention discloses a crystal oscillator circuit which comprises a first crystal oscillator, a second crystal oscillator and an output control circuit. The frequency stabilization time of the second crystal oscillator is shorter than that of the first crystal oscillator. The output control circuit is used for outputting signals generated by the second crystal oscillator before the frequency of the first crystal oscillator is stabilized and outputting signals generated by the first crystal oscillator after the frequency of the first crystal oscillator is stabilized. The work performance of the crystal oscillator circuit is ensured, and waiting time of normal work of the crystal oscillator circuit after the crystal oscillator circuit is electrified is greatly shortened.

A circuit for adjusting frequency of a crystal oscillator includes a basic input output system (BIOS), a platform controller hub (PCH), a buffer, and a capacitor module with a number of capacitors. The crystal oscillator is connected to clock pins of the PCH. An input pin of the buffer is connected to the crystal oscillator. A first end of the each of the capacitors is connected to an output pin of the buffer. A second end of the each of the capacitors is grounded. The buffer includes two enable pins and a control unit controlled by the enable pins. The enable pins of the buffer receive a control signal from the PCH according to the BIOS, and control the control unit to appoint the corresponding capacitor of the capacitor module to be connected to the input pin of the buffer.

The invention belongs to the technical field of an oven controlled quartz crystal oscillator and particularly relates to an oven controlled crystal oscillator. The oven controlled crystal oscillator comprises an analog switch which is connected with a main vibration level of the oven controlled crystal oscillator and a temperature compensated crystal oscillator, and is also connected with a temperature sensing circuit; and a voltage stabilizing circuit (1) which is connected with a temperature control circuit and the temperature sensing circuit, wherein the main vibration level of the oven controlled crystal oscillator is connected with an isolation buffer level (1), the temperature compensated crystal oscillator is connected with the isolation buffer level (2), and an amplification outputlevel is connected with the isolation buffer level (1) and the isolation buffer level (2). When the oven controlled crystal oscillator is started up, an output frequency is a frequency of the temperature compensated crystal oscillator, and when a temperature in a constant temperature zone is risen to be approximate to a constant temperature point, the output frequency is switched to the frequencyof the oven controlled crystal oscillator, so the purpose of reducing starting frequency difference of the oven controlled crystal oscillator is achieved.

The invention relates to a matrix model estimation time synchronization method based on wireless network clustering topology, and belongs to the technical field of wireless sensor network communication. The method comprises the following steps: S1, deploying network nodes, constructing a clustered topological structure, analyzing states of the nodes in different crystal oscillator frequency working modes, and establishing a logic clock model for matrix estimation; S2, according to the clustered topological structure, dividing the sychronization into inter-cluster synchronization and intra-cluster synchronization, selecting a high crystal oscillator frequency mode or a low crystal oscillator frequency mode, and estimating a clock drift relative parameter and a clock offset relative parameter through state functions established by different crystal oscillator frequencies; S3, respectively estimating the clock drift and the clock offset of the high and low crystal oscillator frequency modes by adopting maximum likelihood estimation through the estimated clock drift relative parameter and the estimated clock offset relative parameter, and periodically compensating the clock drift and the clock offset. According to the invention, the communication problem of the network nodes in different crystal oscillator frequency modes is effectively solved, and the network reliability and the synchronization precision are improved.