14 results about "Direct digital synthesizer" patented technology

In one example, an RF oscillator system includes a laser source configured to emit laser light, a housing, a crystalline microresonator disposed within the housing, and a photonic integrated circuit disposed within the housing, the photonic integrated circuit including an optical waveguide network and configured to generate a clock signal based on the laser light. The RF oscillator system may further include at least one photonic wirebond configured to couple the laser light between the optical waveguide network and the crystalline microresonator via evanescent coupling; laser control circuitry disposed within the housing and configured to lock a frequency of the laser light to a resonance of the microresonator to generate the clock signal; and a direct digital synthesizer disposed within the housing and configured to produce a tunable oscillator signal based on the clock signal.

The present application relates to a kind of multi-mode noise interference signal generation method, belong to signal interference technical field, solve the problem that existing cannot dynamically flexibly generate the interference signal of multiple modulation modes and the high development complexity.For method includes: according to noise kind and interference mode, obtain first noise sequence, second noise sequence, third noise sequence, noise interference bandwidth and center frequency;Carrier signal is generated based on center frequency;First noise sequence and noise interference bandwidth are passed into first multiplier, then the output result and carrier signal are passed into adder, and first complex signal is output by direct digital synthesizer;First complex signal and second noise sequence are passed into complex multiplier, and second complex signal is output;Second complex signal and third noise sequence are passed into second multiplier, and noise interference signal is output.The generation of multi-mode noise interference signal dynamically flexibly is realized.

The invention discloses a low-speed speed measurement method for a sine frequency modulation Doppler radar, and mainly solves the problems that the existing debugging test is complicated, and the speed measurement cannot be carried out due to easy lock losing during low-speed flight. The implementation scheme comprises the following steps: determining side frequency times, a modulation index and a modulation frequency; a DDS is used for digitally synthesizing a sine frequency modulation signal, the sine frequency modulation signal is mixed with a local oscillator signal generated by a PLL to generate a radio frequency sine frequency modulation signal, and the radio frequency sine frequency modulation signal is transmitted to specific four directions in turn according to a period; performing phase shifting and frequency mixing on a coupling signal of the echo signal and the transmitting signal, performing down-conversion to a base band, and performing band-pass filtering to obtain a side frequency component containing a Doppler frequency spectrum; carrying out IQ demodulation on the side frequency component and IQ two-path coherent reference signals thereof to obtain an IQ signal of a Doppler spectrum; and calculating the IQ signal of the Doppler frequency to obtain the speed information of the aerial carrier. The method greatly reduces the isolation index requirement of the receiving / transmitting antenna of the Doppler radar, improves the speed measurement capability of the Doppler radar during low-altitude low-speed flight, and can be used for airborne Doppler radars.

The invention discloses a method for upgrading and transforming an analog simulation system based on point-to-point communication, which comprises the following steps of: upgrading a communication protocol, forming communication middleware by establishing a DDS (Direct Digital Synthesizer) information warehouse and packaging a communication data interface in an original system, and establishing connection between operating console software and the DDS information warehouse through the communication middleware, completing data subscription and distribution; the method comprises the following steps: transforming data sending ends of software in an original system, only reserving a sending end generated by a data source and ignoring a forwarding data link among the software through data interface arrangement and transmission process tracing, then calling a corresponding data distribution interface function of communication middleware to replace an original sending end module, and uploading data to a communication bus; each software receiving end in an original system is transformed, each software subscribes to a data interface which needs to be received, then a corresponding data receiving interface function of communication middleware is called to replace an original TCP receiving end module, and needed data is obtained from a communication bus.

A DDS circuit includes a phase accumulator circuit. The phase accumulator circuit includes a clock input being configured to receive a clock signal. The phase accumulator circuit includes a frequency tuning register configured to receive a frequency tuning word (FTW), and a phase shift register configured to receive a phase shift word (PSW). The phase accumulator circuit also includes a phase increment sub-circuit configured to increment a phase signal output by the phase accumulator circuit by a predetermined phase increment based on the clock signal and / or based on the FTW. The phase accumulator circuit further includes a feedback path configured to feed back the phase signal to the phase increment sub-circuit. The phase accumulator circuit further includes a phase correction sub-circuit configured to adapt the phase signal fed back to the phase increment sub-circuit based on the phase shift word.

The invention provides a cloud edge collaborative data distribution method and system. Relates to a digital information transmission method and system. The method comprises the following steps: acquiring a service priority of to-be-distributed data; when the service priority is a high priority, routing the data to be distributed to a DDS (Direct Digital Synthesizer) transmission channel; adjusting the QoS strategy of the DDS transmission channel based on the current network state of the edge node; and distributing the data to be distributed through a DDS transmission channel according to the adjusted QoS strategy. When the service priority is a low priority, routing the data to be distributed to an MQTT transmission channel; and transmitting the to-be-distributed data to a cloud end in a zero analysis mode.

The invention, which relates to the technical field of the precision measuring instrument, discloses a low-temperature-drift digital phase-locked eddy current sensor circuit comprising an MCU, an excitation signal generation module, an AC bridge module, and a high-speed precision ADC sampling module. The excitation signal generation module generates a high-stability 50kHz sine wave excitation signal through high-precision DAC and DMA transmission by adopting a DDS (Direct Digital Synthesizer) mode; the AC bridge module suppresses common-mode interference caused by probe temperature excursion by using a reference coil; the high-speed precise ADC sampling module is used for synchronously digitizing bridge output and excitation signals; the temperature compensation module performs real-time software compensation on the residual temperature excursion through an integrated digital temperature sensor and a pre-calibrated polynomial model; a digital phase-locked demodulation algorithm is realized in the MCU, and a displacement related amplitude is accurately extracted through digital multiplication and low-pass filtering. The circuit fundamentally inhibits temperature drift from hardware and software levels, and realizes high-precision and high-stability eddy current displacement measurement.

The invention provides a deep learning-based countering airspace signal processing method and device, and belongs to the technical field of airspace signal countering. The method comprises the following steps: acquiring an unmanned aerial vehicle control signal, carrying out online learning on the control signal by adopting a 32-bit fixed-point operation artificial neural network ANN, and analyzing to obtain an analysis result containing the frequency, the frequency point and the rate of the control signal; the artificial neural network ANN is realized through FPGA (Field Programmable Gate Array) modularization; based on the analysis result, generating a digital source signal with the same frequency as the unmanned aerial vehicle control signal; performing FSK modulation on the digital source signal by adopting a DDS (Direct Digital Synthesizer) algorithm; and carrying out power amplification and directional emission on the modulated signal to realize airspace signal countering. The complex signal analysis precision can be improved, the hardware resource consumption is reduced, and the real-time performance and the cost are both considered.

In one example, an RF oscillator system includes a laser source configured to emit laser light, a housing, a crystalline microresonator disposed within the housing, and a photonic integrated circuit disposed within the housing, the photonic integrated circuit including an optical waveguide network and configured to generate a clock signal based on the laser light. The RF oscillator system may further include at least one photonic wirebond configured to couple the laser light between the optical waveguide network and the crystalline microresonator via evanescent coupling; laser control circuitry disposed within the housing and configured to lock a frequency of the laser light to a resonance of the microresonator to generate the clock signal; and a direct digital synthesizer disposed within the housing and configured to produce a tunable oscillator signal based on the clock signal.

A sine wave generation circuit includes: a first direct digital synthesizer generating a digital sine wave fundamental signal having a frequency f0 in a normal operation mode and a calibration mode; a second direct digital synthesizer generating a digital second harmonic correction signal having a frequency 2f0 in the normal operation mode; a correction circuit superimposing the digital second harmonic correction signal on the digital sine wave fundamental signal; a D / A converter converting an output of the correction circuit into an analog sine wave signal; an output buffer receiving the analog sine wave signal and outputting an analog sine wave output signal; an A / D converter converting the analog sine wave output signal into a digital signal in the calibration mode; and a processing circuit generating a spectrum based on the digital signal in the calibration mode and setting a parameter of the second direct digital synthesizer based on the spectrum.

The invention discloses a microwave photon fast frequency hopping signal generation system and method. The system comprises a master laser, a light beam splitter, a slave laser, a semiconductor optical amplifier, an IQ modulator and a photoelectric detector. The main laser generates a single-frequency optical signal, and the single-frequency optical signal is modulated by the low-carrier-frequency radio-frequency signal gain switch to generate a wide-spectrum optical frequency comb; the method comprises the following steps of: dividing an optical signal into an upper branch and a lower branch through an optical beam splitter, injecting the optical signal into a slave laser through a polarization controller and a circulator to perform frequency-selecting filtering, then increasing the rejection ratio through a semiconductor optical amplifier, and loading the lower branch to a communication signal to control the phase difference between an I path and a Q path in a modulator, when carrier suppression single sideband modulation is realized, a + 1 order sideband and a-1 order sideband can be flexibly selected; and finally, beat frequency is carried out on the upper and lower branches through a photoelectric detector to realize communication signal output in a double-frequency coverage range. According to the invention, the difficulty of realizing a frequency hopping signal in a high carrier frequency and broadband range by a direct digital synthesizer in an electronic domain is greatly reduced.

The application discloses a nanosecond pulse laser driving control device and method, relates to the technical field of nanosecond pulse lasers, and comprises a main control module connected with a digital-analog conversion module, a direct digital synthesizer module, a reference operation and current monitoring module, a signal output selection module and a signal coupling and current monitoring module respectively; the reference operation and current monitoring module is connected with the digital-analog conversion module; a pulse signal generation and conditioning module is connected with the direct digital synthesizer module and the signal output selection module respectively; the signal coupling and current monitoring module is connected with the signal output selection module; the reference operation and current monitoring module and the signal coupling and current monitoring module are connected with a target nanosecond pulse laser, and the application can improve the stability and reliability in the driving control process of the target nanosecond pulse laser.

The invention belongs to the technical field of laser driving, and relates to a laser driving system with optical waveform feedback. The system comprises a driving circuit, an optical feedback circuit and a control system, the driving circuit is a multi-phase interleaved BUCK circuit and is used for providing large-current and low-ripple driving pulse current for the laser; the optical feedback circuit comprises a photoelectric detector, a trans-impedance amplifier and a fully differential amplifier, and is used for collecting a laser signal output by the laser and converting the laser signal into an electric feedback signal; the control system comprises an FPGA, a high-speed ADC and an upper computer. The FPGA comprises a waveform processing unit, a DDS (Direct Digital Synthesizer) module, a digital integrator and a SerDes module; and the FPGA realizes laser waveform high-fidelity driving and stable output power control through double closed-loop control. According to the invention, a waveform feedback technology is adopted, high-fidelity driving of a laser output waveform is realized, and the stability of output power can still be maintained after waveform adjustment.

The invention discloses a variable-rate FSK (Frequency Shift Keying) modulation and demodulation method, device and system based on an FPGA (Field Programmable Gate Array), and belongs to the technical field of FSK modulation and demodulation. Based on the FPGA, the method comprises the following steps of: controlling selection of a frequency word according to data to be sent during signal transmission, controlling updating of the frequency word according to a preset symbol rate, controlling a DDS (Direct Digital Synthesizer) to generate FSK modulation signals with different modulation orders by the frequency word; the operation frequency of the DDS is a modulation signal sampling rate; when a signal is received, a variable multiple CIC decimation filter is firstly used for decimation according to integral multiples, the sampling rate of the received signal is reduced, then Farrow structure fractional multiple decimation filtering is used for adjusting the sampling rate to a first symbol rate, and FSK demodulation and bit synchronization recover data in the adjusted signal. According to the invention, the transmission rate can be dynamically adjusted according to the channel state, the spectrum resource utilization rate is improved, and the transmission performance is improved.