37results about How to "Fast frequency conversion" patented technology

The invention discloses a quick acquiring method for multi-frequency-point bioelectrical impedance. A multi-frequency-point composite excitation source Vin is realized based on a DDS (direct digital synthesizer) principle by means of FPGA (field-programmable gate array) programming, the composite excitation source Vin is loaded onto reference resistance Rref and to-be-tested organism electric impedance Zx simultaneously, corresponding amplitudes Ampref and Ampx and phase angles Degref and Degx of the Vref and Vx on frequency points can be acquired accurately by reasonably selecting sampling frequency fs and points N of DFT (digital Fourier transform) and by only performing DFT on the Vref and Vx on the several needed frequency points, and further amplitudes of the to-be-tested organism electric impedance Zx on the frequency points are acquired. The quick acquiring method has the advantages of high impedance acquisition accuracy, small operation amount, high anti-jamming capability, short scanning time and the like.

The invention discloses a broadband low-noise frequency modulation signal source. A high-stability clock module has two clock signals as output, the first clock signal as output is directly connected with the reference clock end of a DDS module, and the second clock signal is connected with the input end of a power divider; the power divider divides the second clock signal into haves and respectively outputs the two haves through two output ends, wherein one half is output to a DDS configuration module; the DDS configuration module outputs a configuration signal to the DDS module, the DDS module, after receiving the configuration signal, generates a frequency modulation signal by use of a phase synthesis and table look-up method and outputs the frequency modulation signal through a waveform output end; the waveform output end is respectively connected with a first phase-locked loop circuit and a second phase-locked loop circuit through a low-noise amplifier; output of the first phase-locked loop circuit is taken as an emission local oscillator; and output of the second phase-locked loop circuit is taken as a receiving local oscillator. The signal source provided by the invention can meet the demands for high linearity and low phase noise of a broadband frequency modulation signal source.

The invention discloses a multiplexing delay unit circuit, and aims to implement a delay unit circuit with multiplexing function, implement a loop oscillator of different delay unit stages with as low design overhead as possible and acquire multiple oscillator gains. The invention adopts the technical scheme that: the signal input end of a delay unit is connected with an analog switch circuit; and the analog switch circuit consists of a first analog switch K1 and a second analog switch K2, wherein the K1 is connected with a first input signal IN1 under the control of a first control signal C1, the K2 is connected with a second input signal IN2 under the control of a second control signal C2, and the other ends of the K1 and the K2 are connected with the signal input end of the delay unit. The multiplexing delay unit circuit can receive two paths of input; and an oscillator consisting of the multiplexing delay unit circuit can provide multiple gains, and the area and the power consumption overhead of the oscillator are greatly reduced compared with a conventional variable gain oscillator.

The invention relates to a frequency shift keying modulation method with configurable carrier frequency and an application structure thereof. A single-chip microcomputer writes preset frequency control words in a frequency register group; a baseband signal controls a multiple-for-one data selector to output the corresponding carrier frequency control word signal to the input end of a synchronization register; according to the different numbers of terminals selected by the data selector controlled by the baseband signal, different carrier frequency numbers and frequency shift keying modulation can be realized. By adopting the method provided by the invention, the carrier frequency value is configurable and can be adjusted according to the specific circumstances of a channel so as to adapt to the character of the channel; and the method has the advantages of stable performance, high precision, fast frequency conversion speed, continuous phase output in the frequency shift and strong anti-interference capacity.

The invention discloses high-stability combined region time service frequency generation equipment and aims to provide time service frequency generation equipment with high reliability, high length stability and a wide application range. The invention adopts the technical scheme that a receiving switching unit inputs two paths of selected satellite second signals from different sources into a locking unit to carry out frequency locking, two paths of phase-locked standard frequency signals generated by the locking unit and are respectively output to a signal processing unit A and a signal processing unit B; one path of satellite second signal is also used for carrying out frequency correction on a rubidium clock connected in parallel between a three-selection two-open device and a first analog phase-locked loop PLL_A, and one path of standard frequency signal is generated and transmitted to a signal processing unit C; and the signal processing units carry out signal shaping, amplification, shunting and coding on three paths of standard frequency signals from different sources, the obtained signals are subjected to frequency division, output to a far-end time service unit and are converted into optical signals by an optical-electrical converter, and the optical signals are transmitted to an equipment machine room by one or multiple paths of optical fibers and then are converted into electric signals, and the electric signals are transmitted by an antenna so as to complete a clock time service of a receiving end.

A method for extracting geodetic/geodesic distance/ranging information with a signal generator for generating at least two HF modulation frequencies in the MHz- up to the GHz-range requires a system with a system-input, an optical radiation source , at least one target object (3a, 3b) and a receiver (4'') with a system output and an analysis/evaluating electronics. Initially, the system is excited with at least two , especially synthetic, modulation frequencies, preferably a group of discrete modulation frequencies, by applying at least one excitation signal at the system input. At least one system response is picked up at the system output and distance /ranging information is derived from the signal shape of the system response by the analysis electronics. Independent claims are included for (a) a device for carrying out the method, for (b) a geodetic/geodesic measurement instrument, especially a theodolite, for (c) a scanner for three-dimensional image-scanning and for (d) use of the device.

The invention discloses an output device of different sources of frequencies, and aims at providing the frequency source device of fast switching, high reliability and accuracy and high length stability. Two paths of satellite second signals, of different sources, are processed by a locking unit to generate two paths of phase-locked standard frequency signals, the two paths of standard frequency signals are output to an amplification output unit A and an amplification output unit B, one path of the signals is provided for a rubidium clock connected, in parallel, between a two-of-three switch and a first analog phase-locked loop PLL_A for frequency calibration, a rubidium clock clean up unit generates one path of standard frequency signals and transmits the path of signals to an amplification output unit c, two clean up oscillators in parallel connection lock signals of themselves in signals which take rubidium clock frequency signals as reference, output signals of the rubidium clock clean up is transmitted to the amplification output unit c, and thus, three paths of standard frequency signals of different sources are output.

The invention discloses an automatic frequency conversion method for a DDR memory controller. A step S10, a DDR memory controller is initialized. A step S20, the DDR memory controller calculates the bandwidth utilization rate u_cal of the DDR SDRAM under the current frequency point Freq_cur in each frequency conversion time interval t_interface. A step S30, the DDR memory controller calculates a frequency conversion step length freq_step, a new value of a frequency conversion time interval t_interval and a new frequency point value Freq_new. A step S40, the DDR memory controller takes the highest frequency point Freq_max and the lowest frequency point Freq_min as an upper limit and a lower limit respectively to adjust the new frequency point value Freq_new. A step S50, the DDR memory controller initiates or does not initiate hardware frequency conversion on the DDR SDRAM according to the new frequency point value Freq_new, and updates the last frequency conversion state last_fc. A stepS60, the DDR memory controller updates the frequency conversion time interval t_interface as a new value, and returns to the step S20. The method provides a method for realizing automatic frequency conversion of the DDR SDRAM in a hardware form.

The invention provides an ultra-wideband sweep-frequency pulse power detecting device and method. No requirement on the bandwidth in the pulse of the to-be-measured pulse signal is needed; and measurement of the radar signal pulse power in an ultra-wideband high-power range from an L waveband to an X waveband is realized. The invention provides a plan of frequency conversion of a C-band signal andan X-band signal by using a local oscillator source, so that the circuit devices are reduced and the costs are lowered; and simple and unified controlling of the local oscillator signal frequency isrealized. Besides, a main control unit is used for controlling the frequency of a local oscillator signal according to the central frequency of a detected signal and a C-band signal or the X-band signal can be mixed to be at an L band or S band in a narrow range of the local oscillator signal, so that the requirement on the local oscillator source is reduced, more types of local oscillator sourcesare provided, and the device cost is lowered.

The invention discloses a frequency synthesizer for receiving ultra-short wave and microwave frequency band wireless signals. The frequency synthesizer comprises a frequency synthesizer body and a DDSunit. The DDS unit comprises a DDS chip, and the output end of the DDS chip is electrically connected with the input end of a phase accumulator through a wire. The invention relates to the technicalfield of frequency synthesizers and discloses a frequency synthesizer and a method for receiving ultra-short wave and microwave frequency band wireless signals. According to the invention, the frequency synthesizer designed by matching a field programmable gate array (FPGA) technology with a direct digital frequency synthesis (DDS) technology is adopted. The required frequency control word can bequickly obtained. The overall performance of the synthesizer is greatly improved. Pseudo-random numbers are generated through the FPGA main control module. The random frequency hopping of the frequency synthesizer can be accurately achieved. The frequency synthesizer has the advantages of being high in frequency conversion speed, high in frequency resolution, high in anti-jamming capability and the like. Meanwhile, the output frequency range of the frequency synthesizer is greatly widened, and the use requirements of actual users can be met.

The invention discloses an anti-interference vehicle-mounted communication system. The system comprises a central processor, a communication module, a positioning module, a signal transceiver, a signal converter, a timing module, a frequency conversion module, an alarm module and a power supply module. The central processor, the communication module, the positioning module, the signal transceiver,the signal converter, the timing module, the frequency conversion module, the alarm module and the power supply module are all arranged in the communication host. According to the present invention,the structure is reasonable, and by arranging the timing module and the frequency conversion module, the automatic frequency changing and switching are achieved after the timing is performed, such that the interference probability is substantially reduced.