55 results about "Frequency frogging" patented technology

A method and apparatus for physically secure communication over machine-to-machine (M2M) networks is claimed, through the use of frequency-hop and random access spread spectrum modulation formats employing using truly random spreading codes and time/frequency hopping and receiver selection strategies at the transmitters in the M2M network, blind signal detection and linear signal separation techniques at the receivers in the M2M network, completely eliminating the ability for an adversary to predict and override M2M transmissions. Additional physical security protocols are also introduced that allow the network to easily detect and identify spoofing transmissions on uplinks and downlinks, and to automatically excise those transmissions as part of the despreading procedure, even if those transmissions are received at a much higher power level than the intended transmissions. Extensions to weakly and strongly macrodiverse networks are also described, which provide additional efficiency and security improvements by exploiting the route diversity of the network.

The invention is applicable to the technical field of positioning, and provides an indoor positioning device. The indoor positioning device comprises a base, a light source, a rotating member, a rotating shell and a controller, wherein the rotating shell is divided into a plurality of coding rings, each coding ring is divided into a plurality of coding bits, an angle of each coding bit is 360/N degrees in the latitudinal direction, and the coding bits of different coding rings are different in configuration mode; a plurality of coding bits of the coding rings are of a light transmitting state, more than two continuous light-proof coding bits do not exist, and a plurality of coding bits, which are configured in a specific mode, form a start bit and a stop bit; each coding ring comprises a special coding bit; and the base is further provided with an optical coupler, the side, which faces to the base, of the rotating member is provided with a light blocking piece, and frequency hopping occurs every time when the rotating member drives the light blocking piece to penetrate through a clamping slot. The indoor positioning device realizes positioning by being combined with light signal sensing of a receiving terminal through the special rotating shell and the hopping light source, the structure is simple, and the positioning method is novel, accurate, good in stability and low in cost, thereby being suitable for indoor high-precision positioning.

The invention discloses a method and system for realizing high-security fast frequency-hopping transmission. According to the method, during the transmission of data, a transmitting terminal carries out bit, modulation mode and power distribution on subcarrier clusters of data to be transmitted according to carrier frequency-hopping information specified by a current time slot, then, all subcarrier data are transmitted to a receiving terminal through digital-to-analog (D/A) conversion after all of the subcarrier data are mapped to a time domain by using an IFFT (Inverse Fast Fourier Transform) method, and the processing process of the receiving terminal is an inverse process of the transmitting terminal. The system disclosed by the invention comprises a carrier frequency-hopping information generation device, a subcarrier data dynamic allocation device, a subcarrier data dynamic demodulation device, an IFFT module, an FFT (Fast Fourier Transform) module, a D/A converter, an analog-to-digital (A/D) converter, a transmitting module and a receiving module. The frequency-hopping system disclosed by the invention has the advantages that a frequency hopping rate much higher than that of the conventional single-carrier frequency-hopping communication system can be generated, the concealment performance of frequency-hopping signals is high, the anti-interception capacity is strong, and the availability of a communication system is high. Meanwhile, according to the method and the system for realizing the high-security fast frequency-hopping transmission, the utilization rate of a wireless spectrum is increased because a plurality of subcarriers are used for simultaneous transmission.

The invention provides a high-speed mobile terminal state detection method and device, comprising the following steps: A. recording an automatic frequency control value of a terminal in each preset recording period; B. calculating a maximum frequency value and a minimum frequency value according to the recorded automatic frequency control values; C. determining whether the terminal is at high-speed mobile state or not according to the difference of the maximum frequency value and the minimum frequency value. The detection method accurately detects whether the terminal is at high-speed mobile state or not and the detection method is simple and agile. The detection method also comprises: setting the terminal automatic frequency control based on the maximum frequency value and the minimum frequency value when the terminal is at high-speed mobile state and the district switch or reelection occurs. The detection method solves the problem of frequency jump due to district switch or reelection when the terminal is at high-speed mobile state.

A method for detecting frequency jumps of a navigation satellite's master clock, comprising the steps of i) monitoring the master clock signal that is generated by a master clock onboard of the satellite for a frequency jump, and ii) signaling a detected frequency jump of the master clock signal,

The invention discloses a TTL signal frequency hopping monitoring method. The method is characterized in that the method comprises the following steps: the frequency doubling operation is performed on a reference clock to obtain a clock I; the frequency division operation is performed on a clock to be monitored to obtain a clock II; a trigger is controlled by the clock I to delay the clock II for N ns and 2N ns separately to obtain a clock III and a clock IV; the xor operation is performed on the clock III and the clock IV to obtain a clock V; counting is performed on the clock I by using a counter; when the clock V is in the high level state, the counter is cleared; when the clock V is in the low level state, the counter start to perform counting; when the rising edge of the clock V reaches, the counting value is latched; the latched counting value is delayed for a period through the clock V to obtain a value II; and comparison is performed between the latched counting value and the value II at each rising edge of the clock V so as to obtain a frequency difference value between the current period and the last period of the clock V, and if the difference value is greater than or equal to a given value, then the signal is hopped for one time. The system and method can be widely used in communications, radar and electronic countermeasure.

The invention relates to a multi-station synchronous test system for testing a quartz crystal oscillator by continuously raising temperature. The system is characterized in that a signal output end of a computer is connected with a signal input end of a USB (Universal Serial Bus) digital I/O (Input/Output) converter; the signal output end of the USB digital I/O converter is connected with the signal input end of a PCB (Printed Circuit Board) structure, and the signal output end of the PCB structure is connected with the signal input end of a frequency meter; the signal output end of the frequency meter is connected with the signal input end of the computer, and a power output end is connected with a power input end of the PCB structure. The multi-station synchronous test system provided by the invention has the advantages that: a unique circuit structure design and a matched software design are adopted and digital control of an output frequency is adopted, the test frequency and reliability are optimized, and a good method for detecting frequency hopping of the quartz crystal oscillator in batch is provided.

The invention is suitable for the technical field of positioning, and provides an indoor positioning device. The positioning device comprises a base and a light source, a rotation piece, a driving motor, a rotation shell and a controller which are arranged on the base; the light source is located on the center of an opening of the rotation shell; the rotation shell is divided into multiple coding circles in the latitude direction, each coding circle is divided into multiple coding bits in the longitude direction, two or more successive non-light-transmitting coding bits do not exist in each circle, and a start bit and a stop bit are formed by multiple coding bits configured in a particular mode; the configuration of the coding bits of different coding circles is different; an optical coupler with a card slot is arranged on the base, the rotation piece is provided with a light-blocking sheet, the light-blocking sheet penetrates through the card slot once, and one time of frequency jump of the light source occurs; the positioning device further comprises a receiving end used for inducting optical signals and frequency jump and performing positioning. According to the indoor positioning device and the positioning method, the rotation shell and the jump light source are combined with the receiving end to be used for inducting the optical signals and achieving positioning, and the structure is simple and concise; the positioning method is novel, accurate, good in stability and low in cost, and is suitable for indoor highly-precise positioning.

The invention discloses a detection method for frequency hopping changes of a crystal oscillator. The detection method comprises the following steps: step 1, the crystal oscillator is cooled in a temperature-controlled cabinet to reach a low temperature; step 2, at a room temperature, a frequency output curve of the crystal oscillator heated gradually from the low temperature to the room temperature is formed through a test, fitting software is utilized for judging whether the crystal oscillator has the frequency hopping changes; and step 3, a heater is utilized for heating the crystal oscillator quickly to reach the highest working temperature of the crystal oscillator, a frequency output curve of the crystal oscillator from the room temperature to the high temperature is formed through a test, and whether the frequency output of the crystal oscillator has the hopping phenomenon is judged. The detection method for the frequency hopping changes of the crystal oscillator has the advantages of being simple in operation, high in detection speed, accurate and reliable in judgment, high in detection efficiency and the like, and is especially suitable for detection of performance, related to the frequency hopping changes, of the crystal oscillator in a mass production process of the crystal oscillator.

The invention discloses a GNSS satellite clock state of health monitoring method. Mutual effective verification can be performed for the satellite clock abnormal state by using multiple satellite clock difference data so that the problems of fault location difficulty, false alarm, early warning difficulty and poor timeliness causing various abnormal phenomena of the satellite clock can be solved,and long-term real-time monitoring of the state of health of the satellite clock can be realized. The method comprises the steps that the frequency and drift rate data are acquired through the primaryand secondary differential precision clock difference data, and the phase and frequency hop is detected by using the median method; fitting of the clock difference is performed by using the quadraticpolynomial so as to acquire the long time phase residual and the residual standard deviation; statistics of the frequency stability of the satellite clock is performed by using overlap hadamard variance; and finally various indexes are comprehensively evaluated, and the early warning information of the change of the satellite clock performance and the alarm information of the frequency and phasehop are given. The result proves that the satellite atomic clock state of health monitoring method using phase fitting residual based on multiple data sources is feasible.

The invention discloses a high-precision random frequency hopping DDS frequency synthesizer, belonging to the technical field of signal sources. The synthesizer of the invention comprises a FPGA maincontrol module, a DDS chip, a PLL reference source module, a power management module and a low-pass filter. The synthesizer of the invention can quickly obtain the required frequency control word, reduce the frequency hopping time to 100 nanoseconds, greatly improve the performance, and realize the random frequency hopping by realizing the pseudorandom ordinal number in the FPGA, adopts a programmable modulation mode of DDS chip AD9914 to improve frequency accuracy. The frequency control word needs to be updated is calculated faster, the number of registers is reduced, and the control word issent down through the parallel port to realize the fast frequency hopping. By using an LFSR linear feedback shift register to generate a pseudorandom number, the random frequency point is calculated,and the random frequency control word is obtained by FPGA internal operation, so that the random frequency hopping is realized.

A device for testing power grid adaptability of a wind power generating unit comprises two modularized multi-level current converters in back connection, a disturbance generating module and a direct-current-charging starting module. The disturbance generating module comprises a software signal generating unit used for generating disturbance control signals and a control unit used for executing the control signals to generate disturbance signals, and the disturbance generating module is connected with the modularized multi-level current converter connected with a 35KV bus of the wind power generating unit. The device has the advantages that flexible simulation of various disturbances like voltage fluctuation, frequency hopping, voltage harmonic or three-phase unbalance and flickering of the wind power generating unit under a grid-connected voltage level; the modularized multi-level current converters are adopted, a transformer is not needed, and the device can be directly connected in a power grid, at a 35KV grid-connected voltage level, of a current wind power generating unit.

The invention discloses an SAI phase-locked loop method applicable to a non-ideal power grid. The method comprises steps of: extracting three-phase power grid voltage, transforming the power grid voltage to a [alpha][beta] coordinate system through Clarke transform, extracting the positive sequence fundamental wave of the voltage transformed to the [alpha][beta] coordinate system by using an SAI regulator, subjecting the extracted positive sequence fundamental wave to Park transform in order to transform the same to a dq coordinate system, passing the output of a q axis through a PI regulatorto obtain the synchronous angular frequency of the power grid, and obtaining the phase angle of the power grid after integration. The method not only can accurately track the phase under the balance state of the power grid, but also can accurately obtain a power grid synchronization signal under non-ideal power grid environments such as three-phase imbalance, voltage sag or swell, harmonic pollution and frequency jump, greatly expands the application of the phase-locked loop, and improves tracking accuracy of the power grid synchronization signal.

A transmit frequency is generated for a transceiver by a controllable oscillator which generates an oscillator frequency, a divider by a factor N, and a mixer stage with a subsequent band filter. Signals with the oscillator frequency and the oscillator frequency divided by the factor N are to the mixer stage to generate an output signal at the transmit frequency.

The invention belongs to the technical field of frequency standard fault detection, and discloses an anti-outlier adaptive Kalman filtering method for frequency scale output hopping detection. The anti-outlier adaptive Kalman filtering method for the frequency scale output jump detection comprises the steps of enabling the outlier adaptive Kalman filter to perform recursive filteringby utilizing the observation data, and meanwhile, obtaining the ratio of the actual variance to the theoretical variance of measurement information according to facts; and obtaining a posterior frequency deviation matrix according to the priori frequency deviation matrix, obtaining a frequency deviation gain matrix according to the priori mean square error of the priori frequency deviation, and obtaining a posterior frequency deviation mean square error matrix according to the gain matrix. According to the present invention, the sample data with frequency hopping or outliers often enables a Kalman filter to perform error correction in state prediction of a system, so that a filtering result is deviated and even diverged, and the filtered data can be closer to a real state after the innovation is weighted.

The invention belongs to the technical field of communication, and particularly relates to a communication interaction mechanism design based on frequency hopping for a cognitive radio network. Transceivers of cognitive transmitting or receiving nodes hop periodically on all N authorized channels according to a certain frequency hopping sequence, so that the aim of fully utilizing idle authorized spectrum resources on the premise of avoiding interference on authorized user communication is fulfilled. At the start of time slots, the transceivers are switched to new authorized channels firstly by the transmitting or receiving nodes, and then real-time spectrum sensing is performed on the authorized channels. Being similar to an existing cognitive radio network control information interaction method based on frequency hopping, a control information interaction method based on frequency hopping and supporting node priorities provided by the invention is characterized in that periodical frequency hopping convergence of cognitive transmitting and receiving nodes having the same priorities on all accessible channels can be realized.

The invention belongs to the technical field of communication signal modulation analysis under a non-Gaussian noise environment and discloses an MFSK signal modulation identification method under Alpha stable distribution noise. Generalized short-time Fourier transform is carried out on a received MFSK signal, thereby obtaining a time-frequency analysis image of the MFSK signal; a frequency hop feature sequence in the time-frequency analysis image obtained through the generalized short-time Fourier transform is extracted; and clustering analysis is carried out on the frequency hop feature sequence through adoption of a blind clustering method, thereby finishing identifying a modulation type of the MFSK signal. For the MFSK signal, under an Alpha stable distribution noise environment, whena mixed signal to noise ratio is greater than 0dB, an identification rate reaches more than 94%, and visibly, the modulation identification effect of the method is relatively good.

The invention relates to a method for generating an SAR echo signal with frequency hopping, and belongs to the technical field of radar target echo simulation. The problem is solved that in the priorart, there is no method for generating the SAR echo signal with center frequency which alternately changes along with a pulse triggering signal. The method for generating the SAR echo signal with frequency hopping includes the detailed steps that an I/Q two base band SAR digital echo signal with center frequency being zero is generated; a data file of the base band SAR digital echo signal is loaded into a radio frequency storage plate card; the radio frequency storage plate card generates a medium-frequency SAR echo signal with center frequency which changes alternately, and the medium-frequency SAR echo signal is sent to a radio frequency system in real time; the radio frequency system conducts up-conversion processing on the medium-frequency SAR echo signal, so that the radio frequency SAR echo signal with alternate frequency change is obtained. Through the method, the SAR echo signal with the center frequency which alternately changes along with the synchronous pulse triggering signal is generated, the coherence of the SAR echo signal is kept, and the application requirements of imaging tests with a high resolution can be met.

The invention discloses a distributed blind channel aggregation algorithm in a cognitive radio network to realize all-channel diversity. The method comprises the following steps that when no data in a user node need to be transmitted, frequency hopping is performed according to a fixed frequency hopping sequence; once the user node has a data transmission requirement, then the user node performs frequency hopping according to another fixed frequency hopping sequence, and transmits a frame to perform aggregation consultation request, after the user node receives the consultation request, the user node replies the consultation information and waits for receiving a data frame. The distributed blind channel aggregation algorithm in the cognitive radio network to realize all-channel diversity provided by the invention overcomes the disadvantages in the existing multichannel blind aggregation method that time or slot synchronization is needed and the aggregation diversity is deficient, and provides a multichannel blind aggregation method which does not need time or slot synchronization, the maximum assembly diversity can be guaranteed and the average aggregation time is small. Experiments show that the distributed blind channel assembly algorithm in the cognitive radio network to realize all-channel diversity provided by the invention is easy to be implemented, high in reliability and has certain anti-interference performance.

The invention provides a high-speed scan method used for a digital monitoring receiver, which adopts a continuous tracking and scanning method and a fast Fourier transform method with large space frequency hopping and is capable of implementing dual-mode high-speed scanning. Before scanning, a system carries out estimation of scanning time through user setting and selects an optimal scan mode; an interrupt mechanism and a highly-efficient mode of storing/taking a ping pong are introduced in inner data storage and interaction processes, so that continuous data storage and transmission can be implemented. By adopting the highly-efficient scan mode and the data processing manner, the expenditure of the scanning time is saved, and the scanning search efficiency is greatly improved. The high-speed scan method has the advantages of economy, high efficiency and the like, and is very suitable for economical monitoring receivers or systems.

The present invention relates to a wireless communication apparatus and a wireless communication method. According to an embodiment, a wireless communication apparatus includes a communication control unit, a transmitting unit and a receiving unit. The communication control unit selects one frequency channel from a plurality of frequency channels and switches the frequency channel to be selected. The receiving unit is configured to receive a reception signal of the selected frequency channel from another wireless communication apparatus. The receiving unit includes an interference wave detection circuit configured to detect an interference wave signal of a detection frequency. The interference wave signal is included in an input signal received during an interference wave detection period. In the interference wave detection period, the reception signal is not received. The communication control unit masks a frequency channel related to the detection frequency among the plurality of frequency channels to create a frequency channel map. The communication control unit does not select the masked frequency channel.

The invention discloses a random radiation radar three-dimensional high-resolution imaging method, which is applied to the field of radar detection and imaging. For the problem that three-dimensionalimaging cannot be carried out due to sharp decrease of the imaging resolution along the space distance dimension with the increase of signal time width in a conventional random radiation radar imagingmethod, the invention provides the method, which is characterized by, according to non-correlation of an echo signal at the sampling time, converting a traditional intra-pulse modulation mode into aninter-pulse modulation working mode; carrying out frequency hopping by utilizing narrow pulse to obtain more observation equations, and improving resolution of the space distance dimension; and carrying out echo rearrangement and recursive processing to obtain imaging results of sections at different distances, and finally, realizing three-dimensional imaging of a target scene. By changing the signal transmission form and echo processing mode, the method improves the resolution of the space distance dimension of random radiation radar three-dimensional imaging.

The invention relates to a method for determining the distance (R) and relative speed (v) of at least one object remote from an observation point, comprising the following method steps: continuous transmission of at least one first and one second electromagnetic signal in each case of a signal period (Tchirp) from the observation point; the signals consist of signal portions (bursts) having a constant frequency and a predetermined equal duration, wherein the signal portions of a signal cover a predetermined modulation range by means of frequency steps; the signals are transmitted interlaced in that signal portions of the different signals follow one another in time, wherein a frequency hop occurs between the successive signal portions of different signals, receiving the signals reflected by the object as an echo signal and carrying out a mixed operation with the transmission signal for transformation of the received signal into the baseband in a common analog channel; carrying out an analog-to-digital conversion and sampling the received signal portions of the echo signals and extraction of at least one sampling value for each signal portion; separately evaluating the sampling values for the different echo signals of the different emitted signals by means of a Fourier transformation stage and determining the frequency of the peaks corresponding to signal portions and determining a phase difference between the echo signals of the transmitted signals, characterized in that the signal portions of the second signal (B) are transmitted by means of the same frequencies as corresponding signal portions of the first signal (A).