647 results about "Frequency meter" patented technology

The invention provides a wireless signal tester calibration device and a method. A frequency meter is used for calibration of an output frequency of output signals of the wireless signal tester; a microwave power meter is used for calibration of output power of output signals of the wireless signal tester; a vector signal analyzer is used for EVM calibration of output signals of the wireless signal tester; a vector signal transmitter and the microwave power meter are used for calibration of power measurement of the wireless signal tester; the vector signal transmitter and the vector signal analyzer are used for calibration of EVM measurement of the wireless signal tester; and thus, reliability of performance test on the corresponding wireless transmitting and receiving equipment by using the wireless signal tester can be ensured. The invention also provides an automatic testing system and a method. The calibration device of the invention can be used for carrying out automatic calibration on the wireless signal tester, and the wireless signal tester after calibration is used for automatically testing to-be-tested wireless equipment.

The invention discloses a digital phase discriminator used for a GPS tame crystal oscillator. The digital phase discriminator used for the GPS tame crystal oscillator comprises a 2N frequency divider, a high level pulse width counter, a low level pulse width counter, a pulse per second clock, a phase difference counter clock, a frequency count value latch and a phase error value latch. The 2N frequency divider is used for performing frequency division on 1 Hz PPS signals output by a GPS module. The high level pulse width counter and the low level pulse width counter are used for counting high level pulse widths and low level pulse widths. The pulse per second clock is in input connection with frequency locking enabled signals provided by the outside, is connected with the GPS and performs frequency diversion on inner pulse per second signals output by an OCXO clock. The phase difference counter clock inputs the inner pulse per second signals and PPS signals output by the GPS module, calculates the time difference of rising edges of the inner pulse per second signals and rising edges of the PPS signals, and outputs count values of the phase difference. The frequency count value latch and the phase error value latch are used for achieving the frequency at which an OCXO tracks GPS signals and the PPS signals and meanwhile output frequency values and phase error values. According to the digital phase discriminator used for the GPS tame crystal oscillator, time sequence design is facilitated, and the problem of lead-lag fuzziness of initial phase errors is avoided; the scheme of serial counters is adopted in the frequency counter and the phase measurement counter, so the frequency of the counter clock will not be affected by counting digits.

The invention discloses an automatic testing system of a temperature compensating crystal oscillator, comprising a power supply, an incubator, a data transmission module, a plurality of crystal oscillating gate modules, a display module and a center control module, wherein the crystal oscillating gate modules comprise a plurality of testing control boards, a plurality of groups of decoders and a plurality of switches, wherein the testing control boards are arranged in the incubator; each testing control board is provided with a plurality of crystal oscillators to be tested; the center controlmodule comprises a computer, a frequency scale, a frequency meter and a temperature control unit, wherein the frequency meter is respectively and electrically connected with the frequency scale and the computer and provided with an interface connected with the crystal oscillators to be tested; and the computer is electrically connected with the crystal oscillators to be tested respectively through the crystal oscillating gate modules and the data transmission module and is also electrically connected with the incubator through the temperature control unit. The invention can test and compensate the crystal oscillator in large scale and high efficiency.

The invention provides a surging predicted control apparatus and control method for marine diesel engine turbine supercharger. The apparatus comprises a pressure sensor, a speed sensor, a V/F modular converter, a frequency meter, an A/D modular converter, a power module, a surging predicted control unit and an air circulating device, an exhaust gas diffluence apparatus, a data storage and alarm indicator. When controlling, at first rotate speed feeding back by the sensor and fluctuation frequency of the turbine supercharger outlet pressure are received, fluctuation frequencies of the outlet pressure and the peak-peak value fluctuation conditions corresponding under each rotate speed obtained by pretest and measured by fact carry out contrast analysis; If surging foreboding is provided in the analytical result and is prevented by controlling air circulating device; if without surging foreboding, the air circulating device is not operated, the supercharger works normally. The invention can greatly reduce occurrence frequency of supercharger surging incident during working in the marine diesel engine to avoid grave accident.

In an optical frequency comb generator the emission frequency of each one of the set of output lasers is repetitively aligned with an associated one of a set of specifically determined frequencies by comparison of that emission frequency with a frequency indicated by an optical frequency meter. The optical frequency meter is repetitively re-calibrated by reference to the emission frequency of each of at least two frequency tuneable calibration lasers emitting at respectively different frequencies. Each of the calibration lasers has its emission frequency continuously or repetitively aligned with the frequency of an associated spectral absorption line frequency standard.

The invention discloses a calibrating device for a vibrating string type strain transducer. Mounting blocks at two ends of the vibrating string type strain transducer are sleeved on a fixed lantern ring, the lantern ring is arranged on a bracket through a locking piece, a spinodal handle is connected with a dial gauge through a threaded differential fine tuning mechanism, the dial gauge is arranged on a gauge stand, and two ends of the gauge stand are connected with the threaded differential fine tuning mechanism and the vibrating string type strain transducer respectively; the number of measuring bars is two, the two measuring bars are fixed at the upper and lower ends of a bracket respectively, two ends of an extensometer are connected with the two measuring bars respectively, the extensometer is connected with a measuring indicator, and the extensometer is positioned on one side of the vibrating string type strain transducer; and a frequency meter is connected with the vibrating string type strain transducer. Based on the differential thread transmission principle, the calibrating device realizes the function of rotary fine tuning movement, has high measurement accuracy, realizes wide-range measurement, is simple to operate, calibrates the vibrating string type strain transducer through simulation, and is applicable to the metering calibration for various graded places.

An automatic test system for measurement and control subsystems suitable for navigation satellites, including integrated baseband equipment, frequency converters, vector signal analyzers, microwave signal sources, power meters, frequency meters, radio frequency channel equipment and test computers. The measurement and control integrated baseband equipment completes the modulation and demodulation of signals below the intermediate frequency, and the baseband processing of telemetry, remote control, and ranging signals; the up-down converter completes the output of the measurement and control integrated baseband equipment, and the conversion of the input signal from the intermediate frequency to the RF frequency; the RF channel equipment completes the RF signal Power control, channel switching, signal filtering; vector signal analyzer, microwave signal source, power meter, frequency meter and other general test equipment are used as performance index test equipment to complete the corresponding index test. All devices are connected to the internal network of the test system through their own network ports or interface conversion devices, and are uniformly scheduled by the system test software running on the test computer to complete the automated test.

The invention disclosed a multifunctional tester, comprising a digital storage oscilloscope module, a digital multimeter module, a function signal generator module and a frequency meter module, which is characterized in that, the control plate of the digital storage oscilloscope is used as the motherboard of the multifunctional tester, and is provided with a multi-computer communication module and a display calculation module which are used to communicate with the data of the digital multimeter module, the function signal generator module and the frequency meter module and display the calculation. The digital multimeter module, the function signal generator module and the frequency meter module acquire the input commands of users by the communication of the motherboard, interact the output data with the motherboard, and then display the output data by the display screen. The invention has the advantages that the invention provides a multifunctional tester covering the common electronic testing devices acquired by the field monitoring which is convenient for the electronic engineers to do common tests, and sets up a testing platform which is convenient for the electronic engineers to do common tests.

The invention relates to a cable single-ended travelling wave distance measurement method using fault signature frequency bands and TT conversion and belongs to the technical field of electrical power system relay protection. Wavelet decomposition is carried out on single-ended travelling wave transient state signals which are then reconfigured into time-domain signals of a plurality of frequency bands, attenuation coefficients and wave velocity of a cable line in each frequency band are relatively fixed, correlation coefficients of initial travelling wave heads (initial wave heads) and fault point reflected wave heads under each frequency band after faults are calculated by adopting relative analysis, the frequency band with maximum correlation coefficients is designed to be a characteristic frequency band, and travelling wave velocity is calculated according to center frequency of the characteristic frequency band. Moment of the travelling wave heads to reach the measurement end is accurately demarcated by using a TT algorithm of time domain conversion in the characteristic frequency band. The cable single-ended travelling wave distance measurement method uses the center frequency of the characteristic frequency band to calculate the travelling wave velocity, reduces errors caused by selection randomicity of the travelling wave velocity in a traditional cable single-ended travelling wave distance measurement technique, is applied to the TT conversion algorithm to demarcate reaching moment of the travelling wave heads, and improves distance measurement accuracy.

The invention discloses an attribute forecasting method. When user touches the screen keyboard (5) to input the alphabet or the attribute (s110), the method identifies the alphabet (s110) and the location of the current word and chooses six best optional alphabets to follow with the special alphabet of the location according to the frequency meter. When choosing the optional alphabets, it does not regard of the alphabet before the last input alphabet and only regard of the last alphabet and the location. The keyboard (5) can display the optional alphabets (s112) to the user with high light.

In accordance with one aspect of the present invention, there is provided a method of calibrating an oscillator within a radio-frequency identification (RFID) circuit for use in an RFID tag. The oscillator has an oscillation frequency. A calibration value is stored within a non-volatile memory associated with the RFID circuit. The oscillator is calibrated in accordance with the calibration value. The storing of the calibration value includes recovering a reference frequency from a test signal supplied to the RFID circuit, calculating the calibration value to correspond to a difference between the recovered reference frequency and the oscillator frequency, and writing the calibration value to the non-volatile memory.

A testing system for testing vibration fatigue performance of an aircraft fuel tank is composed of an electromagnetic vibrator, a sample clamp, a signal output unit, a stabilized voltage supply, a frequency meter, a resistance strain gage, a dynamic resistance strain gauge, a sample and a clump weight. The clump weight is installed in the middle of the sample. The sample is mounted on the sample clamp, and pretension force can be applied by screwing studs on the sample clamp. The sample clamp is installed on the electromagnetic vibrator. The stabilized voltage supply is connected with the signal output unit. The signal output unit is connected with the electromagnetic vibrator so as to control the electromagnetic vibrator. The stabilized voltage supply is simultaneously connected with the frequency meter so as to monitor output excitation frequency. The resistance strain gage adhered to the sample is connected with a dynamic strain meter so as to monitor strain of the sample. The dynamic resistance strain gauge is connected with the frequency meter so as to monitor response frequency of the sample. The testing system has a simple structure, is convenient to operate and is used for testing vibration fatigue performance of an aircraft fuel tank. A test result has important engineering application value for evaluation of structure fatigue life.

The invention discloses an intelligent environment-friendly high-voltage shore power supply system which is characterized by comprising a high-voltage switch cabinet I, a high-voltage inverter connected with the high-voltage switch cabinet I, a high-voltage switch cabinet II connected with an output end of the high-voltage inverter, a high-voltage cable connected with the high-voltage switch cabinet II and ship electric equipment, a voltage transducer II, a frequency meter II and a phase detector II which are connected with the high-voltage inverter by the high-voltage switch cabinet II, a current transducer II connected with the high-voltage inverter by the high-voltage switch cabinet II, a second DSP (Digital Signal Processor) connected with the voltage transducer II, the frequency meter II, the phase detector II and the current transducer II respectively, and a communication module which is connected with a ship power generator and the second DSP respectively, and used for transmitting an amplitude, frequency and a phase of output voltage, and output current of the ship power generator to the second DSP. The high-voltage shore power supply system can monitor a ship power grid at any time, can control a shore power supply to synchronously run with the system, and is reliable and practical.

The invention discloses an automatic testing method for parameters of a microwave oscillator. The automatic testing method comprises the following steps of powering up the to-be-tested microwave oscillator; transmitting a signal to a first coupler by the microwave oscillator, transmitting a main signal of the first coupler to a second coupler by the first coupler, transmitting a main signal of the second coupler to a power meter by the second coupler, transmitting a branch signal of the first coupler to one of a frequency spectrograph and a frequency meter by the first coupler, and transmitting a branch signal of the second coupler to the other one of the frequency spectrograph and the frequency meter by the second coupler; controlling the power meter, the frequency spectrograph and the frequency meter by a control device to test the microwave oscillator, acquiring testing results and storing, and controlling a display device to display. According to the method, automatic testing of the working frequency, the output power and the phase noise of the microwave oscillator can be realized, and data does not need to be manually read and manually recorded, and therefore, the accuracy and the consistency of the testing results are improved, and the testing efficiency is improved. The invention also discloses an automatic testing device for the parameters of the microwave oscillator.

An electronic scanning radar apparatus includes a transmission unit configured to transmit a transmission wave, and a receiving unit including a plurality of antennas receiving a receiving wave coming from a target. The receiving wave is formed from a reflection wave of the transmission wave reflected at the target. A beat signal generation unit is configured to generate beat signals in response to the transmission wave and the receiving wave. A frequency resolution processing unit is configured to obtain complex number data calculated from beat frequencies having signal levels obtained by performing a frequency resolution for the beat signals based on a predetermined frequency width. A peak detector is configured to detect an existence of the target by detecting peak signal levels of the beat frequencies, and a direction detecting unit is configured to calculate an incoming direction of the receiving wave based on a normal equation having an order.

The invention discloses a dominant frequency signal decision circuit and decision method for a microwave frequency counter. The dominant frequency signal decision circuit for the microwave frequency counter comprises a frequency mixer, a local oscillation unit, a band-pass filter, a voltage controlled attenuator, a power comparison unit, a digital-to-analogue conversion unit, a CPU unit and a counting unit. The local oscillation unit provides a frequency mixing local oscillation signal for a frequency meter, and the frequency mixer mixes the measured signal with the local oscillation signal to obtain an intermediate-frequency signal; the band-pass filter filters the intermediate-frequency signal output by the frequency mixer; the voltage controlled attenuator attenuates the power of the intermediate-frequency signal output from the band-pass filter, and the attenuation amplitude is linear to control voltage; the power comparison unit detects the peak of the intermediate-frequency signal input from the voltage controlled attenuator to obtain a peak voltage, samples and holds the peak voltage, compares the sampled and held voltage with a comparison voltage to obtain a control voltage and enables the control voltage to act on the voltage controlled attenuator to attenuate the input intermediate-frequency signal.

The invention relates to a voltage transformer error test power frequency resonance step-up automatic test method in a GIS (geographic information system). An error test method of a voltage transformer Px in the GIS comprises the following steps of: sending out an automatic tuning instruction by a PC (personal computer) machine to control an alternating voltage signal of which the output frequency of a frequency conversion resonance test power supply is 30-300Hz; searching the initial resonant frequency f1 of a second series resonant circuit according to resonance voltage feed back by a resonance monitoring input end; reading the initial resonant frequency f1 by the PC machine; computing the capacitance of GIS pipeline distributed capacitance Cx; computing the inductance value L50 of a GIS pipeline voltage transformer Lx when the frequency is 50Hz; searching the iron core extension length d2 which corresponds to the L50 in database; and displaying the iron core extension length d2 by the PC machine. The method has the advantages that the automatic test of the power frequency resonance step-up when the voltage transformer field error test in the GIS is carried out can be realized, and the efficiency of field test can be improved.

The invention relates to a loading method for a concrete member flexural test, which comprises the following steps: (1) pouring a concrete member and arranging brackets and hole channels at two ends of the concrete member; (2) maintaining the poured concrete member for 28 days, testing the strength and setting the size of load; (3) enabling two screw rods both having two threaded ends to penetrate through the reserved round hole channels in the brackets, connecting the screw rods by using a reinforcement stress meter in the middle, and screwing screw nuts on the two ends; (4) connecting the reinforcement stress meter with an XP02 type vibration wire frequency meter, measuring an initial frequency value f0 of the reinforcement stress meter, and calculating a vibration wire frequency fn corresponding to a tensile stress delta designed for the test; and (5) using a wrench to tighten the screw nuts for applying load till the value on the XP02 type vibration wire frequency meter reaches the vibration wire frequency fn. According to the method, the loading force is reliable, the device is simple, the operation is convenient, the slipping volume is small, the load value is stable, and the method is suitable for the concrete member flexural long-term loading test, especially the loading test in a soaking condition.

A dynamic monitor of landslide or collapse is composed of laser device, the units installed on the base of said laser device as horizontal regulator, horizontal level meter, damper and microscope forreceiving the light reflected from the object to be monitored, the collimator, movable beam diffuser and deflector in the optical channel of laser device, the optical sensor and amplifier in the optical channel of microscope, spectral analyzer, and computer. It can forcast the generation of landslide and collapse earlier.

The embodiment of the invention provides a method and an FPGA (Field Programmable Gate Array) device for performing multi-channel digital frequency measurement. The method for performing the multi-channel digital frequency measurement comprises the following steps of: acquiring a measuring signal of a multi-channel tested instrument through an FPGA; performing counting measurement on the measuring signal by using a frequency counting module in the FPGA to acquire a measuring result; and reporting the measuring result to an upper computer. The FPGA device for performing the multi-channel digital frequency measurement comprises a frequency counting module and a serial port communication module, wherein the frequency counting module is used for acquiring the measuring signal of the multi-channel tested instrument through the FPGA and performing the counting measurement on the measuring signal to acquire the measuring result; and the serial port communication module is used for reporting the measuring result to the upper computer. The embodiment of the invention can provide a technical implementation scheme for realizing a multi-channel digital frequency meter with low cost. The method and the FPGA method have the characteristics of high operability, flexible system structure logic unit, high integration and the like and can fill the blank of multi-channel frequency detection of petroleum apparatus in China.