188 results about "Frequency synthesis" patented technology

The embodiment of the invention provides a broadband signal dynamic generation method and system based on multiple clock sources, and the method comprises the steps: monitoring a target frequency in real time through a field programmable gate array, and automatically switching to a corresponding target clock source based on a frequency band to which the target frequency belongs; correcting the phase difference corresponding to the new and old target clock sources through a phase compensation register when the target clock sources are switched, and loading a compensation value to a phase offset register of a direct digital frequency synthesis chip; a fundamental waveform of a broadband signal is generated based on a direct digital frequency synthesis chip, multiple harmonic components are superposed through a fractional accumulation method, and each harmonic amplitude is independently controlled through a look-up table method; an output signal of the power amplifier is collected through the analog-to-digital converter, error information of the actually measured waveform and the theoretical waveform is extracted, the phase offset register and the harmonic amplitude look-up table coefficient are dynamically corrected, and a target broadband signal is output. Unification of broadband coverage, high resolution and quick response is realized.

The invention belongs to the technical field of near-field imaging, and particularly relates to a microwave and millimeter wave near-field subsurface microscopic imaging device and method based on signal interference, and the device comprises a vector network analyzer, a signal separation device, a phase adjustment device, a semi-steel coaxial line, a displacement platform, and an industrial control computer. The vector network analyzer comprises a signal separation unit, a frequency synthesis source, a first receiver and a second receiver, wherein the frequency synthesis source, the first receiver and the second receiver are respectively connected with the signal separation unit and used for generating microwave and millimeter wave test signals. The signal separation device is respectively connected with the vector network analyzer, the phase adjusting device and the semi-steel coaxial line, and the displacement table is connected with the vector network analyzer through the industrial personal computer; the tail end of the semi-steel coaxial line, which is far away from the signal separation device, is provided with a conical needle tip-shaped near-field probe; and the needle tip of the near-field probe is vertical to the surface of a to-be-detected sample arranged on the displacement table.

The invention designs a broadband intermediate-frequency heterogeneous integrated communication transceiving micro module and a three-dimensional packaging method, and belongs to the technical field of advanced packaging. The micro module comprises a TSV silicon adapter plate, a Fan-out module, an HTCC ceramic substrate and a digital chip. The TSV silicon adapter plate adopts a high-resistance silicon substrate, and a coaxial shielding TSV structure is arranged on the TSV silicon adapter plate and comprises an inner layer signal through hole and an outer layer grounding layer. A frequency synthesizer chip and a radio frequency chip are embedded in the Fan-out module, and high-density horizontal interconnection is realized through a plurality of redistribution layers. The HTCC ceramic substrate is of a multi-layer laminated structure, and an impedance matching network is arranged in the HTCC ceramic substrate. The three-dimensional packaging method comprises the steps of TSV silicon adapter plate preparation, Fan-out module processing, digital chip stacking and system-level integration. High-density packaging of the radio frequency chip and the digital chip is achieved through the three-dimensional heterogeneous integrated architecture, and low-loss transmission of broadband signals is guaranteed through the coaxial shielding TSV structure and the impedance matching network.

The invention discloses a broadband current transformer testing method, device and equipment and a medium, and relates to the technical field of transformer verification. First, first frequency signals of standard current and current to be measured are synchronously obtained, the frequency of the signal to be measured is tracked in real time through a high-speed comparator, and a second frequency signal is accurately generated through the digital frequency synthesis technology. The method comprises the following steps: firstly using a high-order digital filter to measure a broadband signal frequency spectrum, then using an analog mixing technology to shift the signal frequency spectrum, generating a composite signal containing a difference frequency component and a sum frequency component, finally accurately filtering the sum frequency component through the high-order digital filter, and only measuring the difference frequency signal to obtain a ratio error and an angular error of the broadband signal. By converting the measurement of the broadband signal into the measurement of the fixed low-frequency signal, the technical bottleneck of direct sampling in a high-frequency band in the traditional sampling technology is broken through, and the actual measurement ratio error and angular error precision of the broadband current transformer is effectively improved. The system power consumption and the hardware cost are significantly reduced while the measurement precision is ensured, and the reliability and the accuracy of the broadband current transformer test are ensured.

The invention discloses a beat frequency comparison device mediated by an optical frequency comb. The beat frequency comparison device comprises the optical frequency comb, a first frequency stabilized laser, a first beat frequency device, a first frequency mixer, a first high-pass filter, a second frequency stabilized laser, a second beat frequency device, a second frequency mixer, a second high-pass filter, a DDS signal generator, a third frequency mixer and a low-pass filter. Frequency-stabilized lasers output by the first frequency-stabilized laser and the second frequency-stabilized laser and an optical frequency comb output by the optical frequency comb are subjected to beat frequency in the first beat frequency device and the second beat frequency device respectively, and first beat frequency and second beat frequency are obtained; the first beat frequency and the second beat frequency are mixed with the carrier envelope offset frequency of the optical frequency comb, and a first sum frequency and a second sum frequency are filtered out; the first sum frequency obtains a synthetic frequency through direct digital frequency synthesis; the second sum frequency and the synthetic frequency are mixed in the third mixer, and then the difference frequency is filtered out through the low-pass filter. According to the invention, beat frequency comparison of frequency-stabilized lasers with different wavelengths can be realized, and the influence of the stability of the optical frequency comb is avoided.

The invention relates to a small frequency source module with low phase noise, which is applied to the technical field of frequency sources, and comprises a dual-redundancy reference source unit, a dynamic temperature compensation unit, a frequency synthesis unit, an intelligent switching control unit and a structure protection unit, the main reference source module and the standby reference source module both adopt MEMS resonators with the Q value not smaller than 10000, the dynamic temperature compensation unit is used for dynamically adjusting the output frequency of the resonators according to the temperature, and the intelligent switching control unit is used for controlling switching between the main reference source module and the standby reference source module; through collaborative design of the high-Q-value MEMS resonator, dynamic temperature compensation and dual-redundancy intelligent switching, the problems of large size, high phase noise, large temperature drift and low reliability of a traditional frequency source module are solved, miniaturization design is realized, and strict requirements of scenes such as communication equipment and a navigation system on miniaturization can be met.

The invention provides a quartz crystal microbalance resonant frequency detection system, a control method and a terminal, a direct digital frequency synthesis excitation unit is adopted to generate a frequency sweep excitation signal with a preset frequency range and stepping, and the frequency sweep excitation signal is conditioned by a signal injection and conditioning unit and then injected into a QCM sensor. And then the pure amplitude response detection unit measures and quantifies voltage response amplitudes of the QCM sensor under different excitation frequencies, and the resonant frequency intelligent determination unit determines the resonant frequency of the QCM sensor according to the voltage response amplitudes. According to the invention, a QCM self-oscillation circuit does not need to be designed and debugged, a precise phase detection assembly does not need to be configured, the circuit board layout is simpler, and components are greatly reduced. The QCM resonant frequency can be accurately measured only through efficient amplitude detection, a complex algorithm is avoided, the operational capability requirement and the software development difficulty are reduced, the QCM resonant frequency measuring device has the advantages of being simple in structure, low in cost, easy to integrate and the like, miniaturization and low-power-consumption design can be easily achieved, and the QCM resonant frequency measuring device is suitable for portable and wearable application.

The invention discloses a direct digital synthesis method and system based on a mixed fraction proportion. The method comprises the following steps: determining an integer frequency control word, a numerator frequency control word and a denominator frequency control word based on a target frequency, a sampling frequency and a bit width of a phase accumulator; performing a fractional phase accumulation operation based on the sampling frequency, the molecular frequency control word, and the phase accumulator to generate a carry signal; performing integer phase carry and accumulation operation in parallel with the fractional phase accumulation operation according to the sampling frequency, the integer frequency control word and the phase accumulator to obtain an integer phase value; and acquiring a waveform digital amplitude corresponding to the integer phase value, and performing signal conversion according to the waveform digital amplitude to obtain an amplitude signal corresponding to the target frequency so as to improve the precision of the frequency synthesis signal.

The invention provides a multi-channel microwave signal generation method and system with a fixed initial phase, and the method comprises the steps: responding to a triggering signal received by a high-speed clock synchronization module after a pre-configured synchronous clock signal is inputted to the high-speed clock synchronization module; the high-speed clock synchronization module generates a sampling clock signal and a logic clock signal based on the synchronous clock signal, responds to the logic clock signal and inputs the logic clock signal to the high-speed controller, the high-speed controller generates a signal description word while triggering signal input, responds to the sampling clock signal and inputs the sampling clock signal to the direct digital frequency synthesis module; and the direct digital frequency synthesis module generates an analog fundamental frequency signal required by the multi-channel microwave signal source based on the signal description word, responds to the analog fundamental frequency signal and inputs the analog fundamental frequency signal to the phase-locked loop device, and the phase-locked loop device outputs a final target microwave signal.

The invention provides a dynamic phase compensation method based on double DDS modules, and belongs to the technical field of digital frequency synthesis. The invention provides the following technical scheme: 1, a dynamic phase inheritance mechanism: through alternate work of double DDS modules, seamlessly transmitting an integer part and a decimal remainder contained in a phase accumulated value of a main DDS to a standby DDS during switching, and combining a shared clock source and a high-speed multiplexer to ensure phase continuity; 2, remainder compensation closed-loop control is carried out, a remainder accumulator is designed to record truncation errors in real time, FTW is dynamically adjusted through a PID algorithm, and long-term frequency error closed-loop suppression is achieved in combination with feedback of an external frequency meter; 3, according to a dual-mode triggering strategy, time period triggering and phase threshold triggering are supported, switching logic is started when a triggering condition (a fixed period or a phase threshold theta th is set) is met, and the phase accumulated value theta 1 (t) and the remainder epsilon 1 of the DDS1 are transmitted to the DDS2. According to the invention, through dynamic phase synchronization and closed-loop compensation, the problems of DDS phase accumulative errors and switching discontinuity are systematically solved.

The invention provides a method for constellation time keeping in a free operation state of a satellite-borne atomic clock, and the method comprises the steps: generating an adjustable second time frequency signal through frequency synthesis based on a first time frequency signal outputted by the satellite-borne atomic clock; comparing and measuring the phase difference between the two and sending the phase difference to an inter-satellite link; through inter-satellite measurement and interaction, obtaining a clock error between the second time frequency signals of all satellites, and converting to obtain a clock error between the first time frequency signals of all satellites; and on the basis, a clock difference parameter between the constellation time and the first time-frequency signal is calculated and converted into a clock difference parameter between the constellation time and the second time-frequency signal, a frequency adjustment parameter is generated through a control algorithm, and the second time-frequency signal is controlled to gradually approach the constellation time. The invention further provides a device for constellation time keeping in the free operation state of the satellite-borne atomic clock. Therefore, the free operation requirement and the irregular frequency modulation requirement of the satellite-borne atomic clock under the navigation constellation autonomous time keeping scene can be considered, and the constellation autonomous time keeping precision and the user service performance are improved.

The invention provides a vehicle-mounted short-wave communication system performance detection system. The system adopts a modular design and mainly comprises a radio frequency power detection module, a spectrum analysis module and an industrial digital processor module. The radio frequency power detection module generates an initial signal through direct digital frequency synthesis, the initial signal enters the frequency division and phase discrimination controller after being processed by the low-pass filter, and frequency synthesis is completed through the voltage-controlled oscillator. And the spectrum analysis module realizes digital signal processing of the high-speed synchronous radio frequency signal. The industrial digital processor module is responsible for overall control and data processing, and supports a wireless communication technology to realize efficient data interaction. The system integrates a multifunctional radio frequency standard signal source and provides support of various modulation modes. The system solves the problems of poor portability, low detection precision, weak anti-interference capability and the like in the prior art, provides a high-precision and high-reliability detection tool for fault diagnosis and performance optimization of a vehicle-mounted short-wave communication system, and has remarkable technical advancement and market application value.

This invention discloses a stable amplitude control system for a high-Q MEMS resonator. This system is a digital closed-loop drive system based on a field programmable gate array (FPGA) as the control platform and DDS-PLL technology as the control scheme. The system uses a digital phase-locked loop (DPS) algorithm for frequency synthesis to track the gyroscope's vibration resonant frequency and phase. This structure utilizes the DDS algorithm to provide a high-resolution frequency signal, ensuring sufficiently small frequency steps. The PLL's bandpass characteristics also effectively suppress some spurious signals in the DDS output spectrum, achieving the complementary advantages of DDS and PLL. This improves the dynamic performance of the high-Q MEMS resonator control system, optimizes the stability accuracy of the MEMS gyroscope's amplitude and frequency, and further enhances the MEMS gyroscope's zero-bias output and anti-interference capabilities.

A frequency synthesis circuit includes a first inductor coupled to receive a first input signal at an input frequency, and a second inductor coupled to receive second input signal at the input frequency and out-of-phase relative to the first input signal. The circuit has first and second transistors with control terminals coupled to the first and second inductors, respectively. A first resonant tank of an inductor in parallel with a capacitor is coupled between a power supply terminal and the first transistor. A second resonant tank of an inductor in parallel with a capacitor is coupled between the power supply terminal and the second transistor. The first and second resonant tanks are tuned to a selected harmonic of the input frequency. An injection-locked oscillator has inputs coupled to the first and second transistors.

The invention relates to the technical field of signal acquisition, and discloses an RFSoC-based inter-board synchronization platform and method, the RFSoC-based inter-board synchronization platform comprises a frequency synthesis board, a time sequence control board and a plurality of acquisition board cards, the output end of the frequency synthesis board is connected with the input end of the time sequence control board and the input ends of the plurality of acquisition board cards, and the output end of the frequency synthesis board is connected with the input end of the time sequence control board. The output end of the time sequence control board is connected with the input ends of the plurality of acquisition board cards; the frequency synthesis board is used for outputting a reference clock signal to the time sequence control board and the plurality of acquisition board cards; the time sequence control board is used for synchronously outputting a synchronous trigger multiplexing signal to the plurality of acquisition board cards according to the reference clock signal, receiving synchronous deviation information of the plurality of acquisition board cards and carrying out time sequence synchronous correction on the plurality of acquisition board cards according to the synchronous deviation information; and the plurality of acquisition board cards are used for synchronously executing corresponding actions according to the synchronous triggering multiplexing signals. The method has the beneficial effects that the synchronism among the acquisition board cards is effectively improved, and the acquisition board cards and the acquisition channels in the acquisition board cards are ensured to be in a synchronous state.

The present invention discloses a multi-stage down-conversion frequency synthesis device and method, belonging to the field of frequency synthesis. The present invention simplifies the circuit and reduces debugging difficulty, making debugging easier. A VCO phase-locked loop also generates a fixed tuned local oscillator frequency using the multi-stage down-conversion method. The appropriate VCO fixed tuned local oscillator point can be flexibly selected based on different YTO frequency bands, effectively avoiding various intermodulation spurs. By mixing the YTO and VCO, the near-end phase noise curve of the YTO loop is brought close to the phase noise curve of the VCO loop, achieving a low phase noise level. Both the YTO loop and the VCO loop achieve low phase noise levels through the multi-stage down-conversion method, further flexibly suppressing intermodulation spurs.

The present invention relates to a satellite navigation signal system design method based on hybrid modulation of direct sequence spread spectrum and frequency hopping. The method comprises: spreading code sequences of multiple signal components being modulated and being then hybrid-multiplexed with signal components corresponding to a same frequency point, and forming a baseband code sequence on the basis of power allocation ratios of the signal components; on the basis of environment conditions, performing signal separation on the signal components corresponding to the baseband code sequence, in order to obtain separated radio frequency signals, and performing recombination and modulation on the signals; if the separated radio frequency signals are authorized signals, controlling a frequency hopping pattern by means of a frequency hopping code sequence, and performing hybrid frequency synthesis modulation on the basis of a center frequency point of the frequency hopping pattern and the frequency of the authorized signals; if the separated radio frequency signals are unauthorized signals, performing direct combining and radio frequency modulation on the unauthorized signals on the basis of a signal frequency point, in order to obtain recombined signal components; and performing signal power amplification on the basis of a center frequency point difference of the recombined signal components, in order to obtain direct sequence spread spectrum navigation signals. The method can greatly improve the anti-jamming capability of navigation signals.

The embodiment of the application provides a kind of wide frequency signal dynamic generation method and system based on multiple clock sources, the method comprises: by field programmable gate array real-time monitoring target frequency, and based on the frequency band of target frequency belongs to automatically switched to corresponding target clock source;When the target clock source is switched, the phase difference corresponding to the new and old target clock source is corrected by phase compensation register, and the compensation value is loaded to the phase offset register of direct digital frequency synthesis chip;Based on direct digital frequency synthesis chip, generate the fundamental wave waveform of wide frequency signal, and superimpose multiple harmonic components by sub-accumulation method, and the amplitude of each harmonic is independently controlled by look-up table method;The output signal of power amplifier is extracted by analog-digital converter, and the error information of measured waveform and theoretical waveform is extracted and dynamically corrected phase offset register and harmonic amplitude look-up table coefficient, and output target wide frequency signal.The application realizes the unity of wide frequency coverage, high resolution and fast response.

The invention discloses a noise frequency modulation signal generation device, which is realized based on a field programmable gate array (FPGA), and adopts the following method steps: S1, in the FPGA, constructing an arbitrarily distributed random number generator to obtain random numbers conforming to distribution; s2, linearly mapping the obtained random number into a frequency modulation noise bandwidth by using a linear mapping method to obtain a random frequency conforming to Gaussian distribution; and S3, converting the obtained random frequency into frequency modulation noise by using a direct digital frequency synthesis technology. Complex linear algebraic operation is simplified into integer addition, subtraction and shifting, FPGA parallelism and special hardware resources are fully utilized, high speed, low resources and high statistical quality are considered, and a reliable hardware noise source is provided for scenes such as communication simulation and radar interference.

The application discloses a direct digital frequency synthesizer based on RBF neural network of phased optimization, which comprises a phase accumulator responsible for generating a phase signal, an RBF neural network module responsible for converting the phase signal into a digital amplitude signal, a digital-analog converter responsible for converting the digital amplitude signal into a low-frequency sawtooth signal and a low-pass filter responsible for converting the sawtooth signal into a smooth analog signal. The RBF neural network module comprises a hidden layer and an output layer, each node in the hidden layer has a corresponding radial basis function, so as to map a corresponding characteristic value for each input phase information, multiply the corresponding characteristic value of each node with the corresponding weight in the output layer, and then sum up to obtain an amplitude value corresponding to the phase information. Compared with the prior art, the application introduces the RBF neural network, so that the direct digital frequency synthesizer has stronger scalability and adaptability when processing complex and nonlinear frequency synthesis tasks.

The application discloses an arrayed multi-path frequency-locked magnetron monitoring system, which comprises an arrayed multi-path magnetron, a multi-path coupling mixer capable of receiving signals emitted by the arrayed multi-path magnetron, a multi-path filter-amplifier assembly connected with an output end of the multi-path coupling mixer, a time-division multi-selection switch connected with an output end of the multi-path filter-amplifier assembly, an output end of an AD sampling assembly is connected with a data processing system and a multi-path frequency synthesis source respectively, an output end of the multi-path frequency synthesis source is connected with a mixing frequency input end of the multi-path coupling mixer, and the monitoring system further comprises a reference clock connected with the AD sampling assembly and the multi-path frequency synthesis source. The application adopts multi-path coupling mixing, multi-path switching, AD acquisition and data processing on multi-path signals in time division, obtains multi-path magnetron parameter information in time division, and improves sampling accuracy by adopting multi-path frequency synthesis source feedback, and reduces equipment volume and power consumption.

The invention discloses a radar beacon device with power measurement feedback adjustment and a power measurement feedback adjustment method. The radar beacon device comprises a data processing unit used for receiving parameters and control instructions, processing uploaded measurement power information and controlling an attenuation value; the signal processing unit is used for outputting a synchronous trigger signal to the power measuring unit; the microwave frequency conversion unit is used for realizing receiving, modulation and frequency synthesis of radio frequency signals; the power measurement unit is used for collecting observation signals, performing synchronous detection by combining with the synchronous trigger signals, and outputting measurement data to the data processing unit; and the display control unit is used for setting equipment working parameters and displaying the current state and power information of the equipment. According to the invention, the power measuring device is additionally arranged to monitor a transmitting signal, and a monitoring result is fed back to the control unit to control the transmitting link attenuator to set a corresponding attenuation value, so that the actual output power is consistent with the set power value, the problem of outputting absolute power is solved, and the requirement of high power precision is met.

The application relates to the field of frequency synthesis technology and discloses a low-phase-noise phase-locked loop spurious suppression system and method, which comprises a control module, an oscillator module connected with the output end of the control module, wherein the oscillator module comprises a plurality of oscillator units, a mixing and filtering module connected with the output end of the oscillator module, which is used for mixing and filtering a plurality of reference frequency signals output by the oscillator module and outputting a target reference signal, a signal selection switch used for receiving a control instruction sent by a central processing unit, a fractional-N phase-locked loop used for receiving a system reference clock signal and outputting a radio frequency output signal, and the central processing unit used for receiving a target output frequency signal and determining the system reference clock signal based on the target output frequency signal and the target reference signal. While the spurious is suppressed, the super-low phase noise characteristic of the reference source is maintained, the output frequency is continuously and accurately kept before and after switching, and the low phase noise and low spurious are simultaneously realized.

A signal source and a scanning method thereof relate to the technical field of testing. The signal source comprises a frequency synthesis module, an attenuator control module, an automatic level control module and a control module. The control module is used for responding to user operation to enter a second scanning mode, and comprises the following steps: configuring an adjusting range of the automatic level control module for adjusting a power value output by the attenuator control module, so that at least two overlapping values exist between first scanning ranges corresponding to any two adjacent adjusting gears; the control display scanning range list comprises adjusting gears and first scanning ranges corresponding to the adjusting gears; determining a second output power range according to the second scanning configuration parameter; an adjusting gear for configuring the attenuator control module is acquired and fixed as a second target gear, and scanning is performed in a first scanning range corresponding to the second target gear; and when the output power value in the second scanning configuration parameter exceeds the corresponding first scanning range, stopping scanning or entering the first scanning mode.

The invention provides an L-band transceiving front-end module. The L-band transceiving front-end module comprises a control unit, and a receiving channel, a transmitting channel, a self-checking circuit, a frequency synthesis unit and a power supply unit which are connected with the control unit, the receiving channel adopts a secondary frequency conversion superheterodyne architecture and is used for converting a received radio frequency signal into an intermediate frequency signal and outputting the intermediate frequency signal to the digital processing part, and the transmitting channel adopts a primary frequency conversion architecture and is used for converting an input intermediate frequency signal into a radio frequency signal and outputting the radio frequency signal; and the frequency synthesis unit is used for providing local oscillation signals for the frequency mixers of the receiving channel and the transmitting channel. According to the invention, the receiving and transmitting isolation is improved, the interference of transmitting on receiving is reduced, the connection between the receiving channel and the antenna in the transmitting mode can be cut off through the design of the receiving on-off switch, the transmitting signal is effectively prevented from entering the receiving channel in series, the purity of the receiving signal is ensured, and the stable realization of the receiving function is ensured.

The application discloses a direct digital synthesis method and system based on a mixed fractional ratio, and the method comprises the following steps: determining an integer frequency control word, a numerator frequency control word and a denominator frequency control word based on a target frequency, a sampling frequency and a bit width of a phase accumulator; performing a fractional phase accumulation operation based on the sampling frequency, the numerator frequency control word and the phase accumulator to generate a carry signal; performing an integer phase carry and accumulation operation in parallel with the fractional phase accumulation operation according to the sampling frequency, the integer frequency control word and the phase accumulator to obtain an integer phase value; and obtaining a waveform digital amplitude value corresponding to the integer phase value to perform signal conversion according to the waveform digital amplitude value to obtain an amplitude signal corresponding to the target frequency, so that the accuracy of a frequency synthesis signal is improved.

This invention discloses a time amplifier with self-cancelling quantization noise and a fractional-frequency division phase-locked loop (PLL), belonging to the field of frequency synthesis technology. The self-cancelling quantization noise time amplifier of this invention is based on a resistor-discharge type time amplifier. A control signal containing quantization error information is output through a slow-slope control signal generator to control the slow-discharge path of the time amplifier. This achieves K-fold time error amplification while simultaneously canceling fractional-frequency division quantization noise. The PLL architecture built based on this amplifier eliminates the need for a large-delay loop digital-to-time converter. The phase noise of the slow-slope control signal generator is suppressed by the time amplification gain, breaking the performance trade-off of traditional architectures. This invention achieves a low-noise, low-power, and high-linearity fractional-frequency division PLL design without degrading the performance of the time amplification phase detector.

The application relates to a digital frequency synthesizer, a signal compensation method, an SOC chip and electronic equipment, and belongs to the integrated circuit field.The digital frequency synthesizer comprises a digital frequency synthesis unit, a phase compensation unit and a phase adjustment unit; the digital frequency synthesis unit is used for generating a first clock signal with a first specified duty cycle according to an externally input first digital phase enable binary code and a multi-path initial phase clock signal; the phase compensation unit is used for generating a target compensation clock signal with a corresponding phase width according to required phase accuracy; and the phase adjustment unit is used for generating an output clock signal with a second specified duty cycle according to the target compensation clock signal and the first clock signal. The first clock signal is compensated by generating the target compensation clock signal with the required phase width, so that a clock signal with an arbitrary duty cycle can be output, and the problem that the existing digital frequency synthesizer can only output a clock signal with a specific frequency is effectively improved.

This application belongs to the field of geophysical exploration technology, and discloses a multi-frequency synthesis method and system for the transmitting waveform of time-frequency fusion electromagnetic method, including: performing Fourier expansion on the time-frequency fusion signal to obtain the DC component represented by the switching angle and each harmonic represented by the switching angle, where one emission period of the time-frequency fusion signal contains two time-domain observation windows; selecting target sub-harmonics from each harmonic to establish an objective function; using a genetic algorithm to calculate the optimal value of the objective function, the switching angle corresponding to the optimal value is the optimal switching angle, and the transmitting waveform is determined according to the optimal switching angle, the length of the time-domain observation window and the starting time interval between the two time-domain observation windows. It solves the problem that multiple signal transmissions are required to complete the detection of a set of frequency points during the electromagnetic exploration process. The generated transmitting waveform can emit a waveform containing multiple frequency combinations in a set of frequency points when detecting a set of frequency points, and multi-frequency joint transmission can reduce the number of transmissions.

1. The name of the design product: local oscillator board (ZP128). 2. The use of the design product: the design product is a frequency synthesis module, which is used to provide a reference frequency source signal and used as a mixing reference signal during frequency conversion. 3. The design points of the design product: in shape. 4. The picture or photo that best shows the design points: perspective view.