58 results about "Random frequency hopping" patented technology

A communication unit (101) and corresponding methods are arranged and constructed to detect acknowledgment messages as an Originator or respond with an acknowledgment message as a Target on a time division channel. The communication unit includes a transceiver (201) configured to support air interfaces (113, 115) with other communication (103, 105) units according to frequency hopping patterns and a controller (203) cooperatively controlling the transceiver to, for example, send a call setup message identifying a target communication unit and a pseudo-random frequency hopping pattern; and to determine whether an acknowledgment message from the target communication unit is present in a signal received according to the pseudo-random frequency hopping pattern.

The system comprises: a baseband signal sequence generator for generating baseband signal sequence; a power control unit for respectively multiplying the baseband signal sequences by different coefficients in order to make the power of discrete spectrum line corresponding to one part of the baseband signal sequence to be as zero, and make the discrete spectrum line corresponding to another part of the discrete spectrum to be as single-frequency pilot frequency; a multiplexing unit for multiplexing the baseband signal sequence outputted from power control unit into one route of data transmitted to the random frequency hopping unit; a random frequency hopping unit for randomly changing the frequency spectrum position of single-frequency pilot frequency in synchronous channel of each frame; and a synchronous pilot frequency generating unit for generating synchronous pilot frequency sequence according to the data after random frequency hopping.

A method and apparatus for performing adaptive null steering in a slow frequency hopping environment. Where base stations have smart beamforming antenna capability and are interconnected by a base station controller, thus accommodating cyclic and pseudo-random frequency hopping, each base station forwards information on arrival time, frequency and received power of all subscriber communications and co-channel interferers to the controller for correlation. Periodicity information relating to co-channel interferers is returned to the applicable base station, to enable the generation of a null in the direction of arrival of the interferer. Where few base stations have smart beamforming capability, frequency hopping is cyclic only, and each base station generates its own periodicity information. Base stations may also calculate direction of arrival and time of arrival information, and forward this to the controller, if applicable. The invention enhances network capabilities including a subscriber localizing capability hitherto unavailable to network operators.

The invention discloses a microwave stare correlated imaging device capable of performing random frequency hopping based on different code speeds. A random radiation unit is used for generating and transmitting a microwave pulse signal according to control information transmitted by a main control unit, the microwave pulse signal forms a microwave radiation field having time-space two-dimensional random features in a target area, the scatter echo of an observation target in the target area is received by a receiving unit, and a correlated imaging device is used for correlating the scatter echo with a microwave radiation field to obtain an inversion image observation target; the microwave pulse signal transmitted by each radiation antenna is the same in the pulse period and the pulse repeating frequency, each microwave pulse signal comprises a plurality of random frequency hopping sub-pulses, a frequency point is selected randomly in a bandwidth range, microwave pulse signals transmitted by different radiation antennas are different in random frequency hopping sub-pulse frequency hopping code speed, and frequency hopping patterns are orthogonal. An ideal time-space two-dimensional random radiation field which is required by microwave stare correlated imaging is realized on the aspect of engineering under the conditions of low code speed transmission, low-speed acquisition and lower bandwidth.

The invention proposes a target motion parameter estimation method for a random frequency hopping radar, and solves the problem that the existing speed measurement scheme has a long accumulation time,a large calculation amount and a poor anti-noise performance. The method comprises the main steps of: designing a waveform parameter for transmitting a random frequency hopping signal and receiving atarget echo; preprocessing digital signals; preprocessing the slow time sampling vector; constructing a difference frequency vector group; constructing a Doppler domain generalized Fourier transformmatrix group; carrying out the generalized Doppler transform and non-coherent processing; carrying out motion compensation processing; and carrying out the coherent integration of distance dimensionsand de-redundance processing to obtain a one-dimensional range profile with the correct target in the plurality of range gates. According to the target motion parameter estimation method for the random frequency hopping radar, a set of dimension decreasing difference frequency vectors are constructed from the target echoes, generalized Doppler processing is performed on each difference frequency vector, and an estimated value of the target radial velocity can be read in the generalized Doppler spectrum after non-coherent integration. The method is short in accumulation time, small in calculation amount and good in anti-noise performance, and is used for target detection and pulse accumulation of the random frequency hopping radar.

A cyclic shift of a reference signal is quantized as a combination of a cell specific cyclic shift with an outcome of a pseudo-random hopping, and an indication of the cell specific cyclic shift is broadcast in the cell. In one embodiment the cyclic shift is quantized as a modulo operation on a sum of the cell specific cyclic shift, the outcome of the pseudo-random hopping, and a user specific cyclic shift, in which case an indication of the user specific cyclic shift is sent in an uplink resource allocation and a user sends its cyclically shifted reference signal in the uplink resource allocated by the uplink resource allocation. The cyclic shift may also be quantized according to length of the reference signal as cyclic_shift_symbol= (cyclic_shift_value * length of the reference signal)/12; where cyclic_shift_value is between zero and eleven and cyclic_shift_symbol is the amount of cyclic shift given in reference signal symbols.

The invention discloses a method for detecting a target echo signal of a random-frequency hopping-frequency agility radar. According to the method for detecting the target echo signal of the random-frequency hopping-frequency agility radar, focusing treatment before detection is carried out on a search trajectory, the blind velocity sidelobe problem can be effectively solved, and the false alarm rate of subsequent detection treatment is reduced; by searching in a target motion parameter space, the signal is subjected to phase compensation to realize coherent accumulation, and the method can solve the problems of range migration and inter-pulse phase jitter at the same time; and when narrow source interference exists in a scene, the method can still realize the effective accumulation of thetarget signal energy, so that a target is detected from an interference background.

The invention discloses a radio frequency identification (RFID) electronic tag random frequency hopping method on the basis of a radio frequency identification system and an implementation method of the radio frequency identification system for enabling electronic tags to randomly select channels, wherein the radio frequency identification system comprises a host computer, a low-frequency exciter, the electronic tags and a controller. The low-frequency exciter awakes the electronic tags entering an excitation area of the low-frequency exciter, and transmits a frequency hopping table to the electronic tags; and the electronic tags which receive the frequency hopping table randomly select a communication channel to establish a communication link with a corresponding controller, so that data are transmitted to the host computer through the controller, or the data from the host computer are received through the controller. According to the method, the communication channel of the electronic tags is randomly selected to avoid channel collision, and the retention time of the transmitted data on a single communication channel is short, so that the data are difficult to capture and resolve, and the safety of the data is ensured; besides, compared with a frequency multiplexing RFID system in the prior art, more electronic tags can be accommodated in the radio-frequency identification system, so that the utilization ratio and the redundancy rate of the channel are improved.

The invention relates to a random frequency hopping method, a communication device and a random frequency hopping system. The stochastic frequency hopping method comprises the steps that a first communication device sends device information of the first communication device to a second communication device through a frequency matching channel; the first communication device receives frequency matching information sent by the second communication device; the first communication device sends synchronization information to the second communication device through a synchronization channel; the first communication device receives reply information which is sent by the second communication device and corresponds to the synchronization information; the first communication device switches a current communication channel to a first channel in a preset frequency band at interval time t, and the first communication device sends communication data to the second communication device through the first channel, wherein the first channel is the channel corresponding to a number of a random sequence in the preset frequency band, the numbers of the random sequence and the channels in the preset frequency band are in one to one correspondence, and the numbers of the random sequence are generated according to the device information of the first communication device.

Method and Apparatus to Perform Reactive Jamming While Simultaneously Avoiding Friendly Pseudo-Random Frequency Hopping Communications is disclosed. The system provides an enhancement to surgical reactive jammers that combines near-real-time jamming capability with the additional feature of allowing tactical communications. The jammer includes a synchronization subsystem that synchronizes jammer lockout frequencies with those frequencies being hopped to by units that are members of a friendly communications network. The synchronization subsystem is coordinated with, and therefore tied to the time-synchronized cryptography of the friendly communications net. As a result, the jammer will be aware, on a real-time basis, which frequency the friendly communications network will next be hopping to. The jammer's awareness of these future frequencies will allow those frequencies to be “locked out” of the jammer's transmission band dynamically.

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.

The method includes steps: (a) based on needs of device, determining lower frequency limit of phase discrimination; (b) embedded type microprocessor selects n pieces of phase discrimination frequencies at random, and the said microprocessor controls hopping pattern generator to generate hopping pattern at random; (c) equal interval hopping frequencies permutation table is designed for each phase discrimination; all basic frequencies table selectable is formed; (d) picking up a group of frequencies and comparing them with lower frequency limit so as to generate current selecting carrier frequency table; (e) pseudo-random hopping pattern generator and current selecting carrier frequency table determines hopping frequencies sequence table, microprocessor selects control parameters of frequency synthesizer; (f) controlling divide down ratio N and reference proportion by subtraction Ro; (g) signal of pseudo-random non equal interval hopping pattern is output from frequency synthesizer.

The invention provides a frequency hopping anti-interception method in an orthogonal frequency division multiplexing (OFDM) system, which can improve signal to interference plus noise power ratio, and lowers the effect caused by broadband interference. The method comprises a small amplitude frequency hopping method for narrow-band interference and a random frequency hopping method for broadband interference. The space of each frequency point is equal to the bandwidth of a subcarrier, and the frequency points are not so excessive; and a plurality of subcarriers are selected to transmit data, a pseudorandom sequence is used for shifting of the subcarrier at each OFDM mark space, so that little signal bandwidth is increased, but the effects of rapid frequency hopping and anti-interception can be achieved simultanesouly. Under the interference of broadband, the scheme of random frequency hopping is adopted, at each OFDM mark space, a relatively small amount of subcarriers are randomly selected to transmit data, so that the signal to interference plus noise power ratio is improved, and the effect caused by broadband interference is lowered.

The invention discloses a distance and velocity two-dimensional high-resolution processing method of sparse frequency hopping signals. The method comprises the following the steps that: frequency hopping codes are randomly extracted from a frequency set so as to form the transmission waveforms of the sparse frequency hopping signals; initial velocity compensation is performed on echo sampling baseband signals; velocity dimension alignment is performed; cross term compensation is performed; distance-dimension iteration interpolation sidelobe suppression high-resolution processing is performed; velocity-dimension inverse Fourier transform processing is performed; and Doppler iterative interpolation high-resolution processing is performed. With the method of the invention adopted, a distance sidelobe suppression problem due to random frequency hopping or spectrum discontinuity in radar signal distance and velocity two-dimensional processing can be solved, and velocity resolution can be improved.

A method for card-reading anti-collision with automatic frequency hopping is provided, which is used for a system in which a card reader simultaneously reads a plurality of cards in radio frequency identification technologies. The method comprises: both the card reader and the cards to be read are configured to have an automatic frequency-sweep function and a function of hopping from a current channel to another channel, and to store access addresses and transaction addresses; when the card reader is in a frequency-hopping card-seeking state, it is in an n-channel frequency-hopping working state, in which, the access address of each channel is the same, and the card reader reads the cards by means of hopping frequencies in a sequence iteratively through n channels. When the card reader detects that two or more cards collide, the card reader sends a command of random frequency hopping, making all the conflicting cards to hop to other channels randomly and to wait to access those channels. The beneficial effects of said method includes: it can quickly realize a card-reading anti-collision mechanism and improve the card-reading speed.

The invention belongs to the field of mobile communication terminals. The invention discloses a format and method suitable for wireless data transmission between a mobile communication terminal and a SIM card so that command session data is transparently and effectively transmitted through wireless transmission interfaces between the mobile communication terminal and the SIM card. Through wireless transmission frame package of a command session data package, error detection of received data, automatically repeated transmission of received error data packages, random frequency hopping on wireless transmission signal channel frequency, using conflict detection of signal channels, and data buffering of command session interactions, etc., highly efficient wireless data transmission is realized between a cell phone and a SIM card; the method has no influence on present data interchange between a cell phone and a SIM card. According to the invention, a SIM card application function menu is established in the cell phone through a SIM card application toolbox so that the cell phone is operated actively by a user to access a network.

The invention relates to a radio frequency equipment communication method and device. The method comprises steps: pair code information is generated according to the first equipment identification code information of the radio frequency equipment and the second equipment identification code information of opposite-end equipment; seeds of a pseudo random frequency hopping sequence are generated based on the pair code information; according to the seeds of the pseudo random frequency hopping sequence, a frequency hopping sequence is generated; and based on the frequency hopping sequence, frequency hopping switching is carried out. The pair code information is generated according to the first equipment identification code of the radio frequency equipment and the second equipment identification code of the opposite-end equipment, the pair code information is used to generate the seeds of the pseudo random frequency hopping sequence, the frequency hopping sequence is further correspondinglygenerated, and finally, according to the frequency hopping sequence, frequency hopping switching is carried out. Frequency hopping switching is carried out according to the frequency hopping sequence, and thus, the problem of co-frequency and adjacent-frequency interference can be effectively avoided, and the hardware overhead and the cost can be greatly reduced.

The invention discloses a contractive mapping-based adaptive random frequency hopping sequence generation method. According to the technical schemes of the invention, the method includes the following steps that: an original sequence is defined, and the definition of a weight is deduced from the original sequence; at an initial stage, the weight is initialized; at a scanning frequency hopping stage, the weight is updated; at a random frequency hopping stage, the weight is updated again, so that a final weight can be obtained; cumulative distribution of the final weight is calculated; a contractive mapping relation is determined according to the cumulative distribution; and a final frequency hopping frequency number set is generated according to the contractive mapping relation. According to the contractive mapping-based adaptive random frequency hopping sequence generation method of the invention, frequency points suitable for data transmission are selected out in a communication process according to a probability, and at the same time, the probability can be updated adaptively according to the change of channel environment, and therefore, the transmission frequency points can converge onto an optimal frequency point, and reliable data transmission is realized; and the weight of which the value is an integer is adopted and is equivalent to the probability, and therefore, the implementation of practice application of the method can be facilitated. The method can be used for efficient data transmission in a frequency hopping system.

The invention discloses an anti-jamming secure communication method for analog video signals in a simplex communication state, which comprises the steps that a frequency point list 1 and a frequency point list 2 shared by the transmitting party and the receiving party are generated; a frequency hopping sequence 3 is generated through the frequency point list 1, and initial synchronization and communication contact between a transmitting terminal and a receiving terminal are completed according to a conventional frequency hopping communication mode; a random frequency hopping scheme in the communication process is designed based on the frequency point list 2, and encryption is performed on the random frequency hopping scheme; the transmitting terminal loads and transmits encrypted information of the frequency hopping of a subsequent communication signal by using a field blanking section of the previous analog video signal; the receiving terminal receives the encrypted information and then decrypts a frequency hopping scheme of a subsequent signal to be received and changes the frequency point of the receiving terminal according to the frequency hopping scheme; and the conventional frequency hopping communication performed according to the frequency hopping sequence 3 is restored at the interval of a certain fixed period, and the synchronization state of the transmitting and receiving system is re-established. The anti-jamming secure communication method can effectively improve the confidentiality and anti-jamming performance of the analog video signals in the simplex communication state on the basis of the original conventional frequency hopping communication.

The invention relates to a frequency hopping method and a frequency hopping device for inter-cell interference elimination in first network equipment. The method comprises the step of sending frequency hopping information to second network equipment, wherein the frequency hopping information comprises resource allocation information, and the resource allocation information comprises at least one of power allocation information, dispatching allocation information and beam forming allocation information. The frequency hopping information further comprises frequency hopping configuration information, wherein the frequency hopping configuration information comprises frequency hopping initial sub-frame information, initial resource allocation information associated with a frequency hopping initial sub-frame and frequency hopping parameters. The invention further provides a method and a device for avoiding interference fluctuation caused by frequency hopping in the first network equipment. The method comprises the step of selecting or reconstructing channel state information corresponding to the current source so as to dispatch user equipment based on at least one piece of channel state information from the user equipment. The scheme provided by the invention realizes random frequency hopping among sub-frames, and the stability of inter-cell interference elimination information in frequency hopping is ensured at the same time.

The invention discloses a hypersonic platform-based random frequency hopping radar sub-aperture synthetic imaging method. The method specifically comprises the following steps: 1, providing compensation; 2, performing relation derivation; 3, compensating and correcting; 4, performing imaging processing; and 5, performing full-aperture imaging. The invention relates to the technical field of radar imaging. According to the hypersonic platform-based random frequency hopping radar sub-aperture synthetic imaging method, after coherent accumulation is carried out on images of all sub-apertures, the intensity of the images at the center pixel of each scattering point image is enhanced due to in-phase addition, and the intensity of surrounding pixel points is weakened due to positive and negative offset, that is, relative to the images of all the sub-apertures, the image bright spot of each scatterer in the synthesized image becomes narrower in the speed direction, so that the lateral resolution is improved, the nominal lateral distance resolution of full-aperture coherent accumulation can be achieved, a high-resolution target image is effectively obtained, and the imaging effect is improved.