1537 results about "Radiofrequency signal" patented technology

The present invention relates to a sensor network having node architecture for performing trust management of neighboring sensor nodes, and to an adaptive method for performing trust management of neighboring sensor nodes for monitoring security in the sensor network. The sensor network includes a base station and a plurality of sensor nodes for reporting sensed information packets to the base station through radiofrequency signals relayed by other sensor nodes. A judge sensor node may have a trust estimator in its node architecture to evaluate trustworthiness of a neighboring suspect sensor node by determining a personal reference and receiving personal references from jury sensor nodes. Based on the trustworthiness of the suspect, the judge may modify a route for transmitting packets to the base station.

A method of slice selective multiple quantum magnetic resonance imaging of an object is disclosed. The method is effected by implementing the steps of (a) applying a radiofrequency pulse sequence selected so as to select a coherence of an order n to the object, wherein n is zero, a positive or a negative integer other than ±1; (b) applying magnetic gradient pulses, so as to select a slice of the object to be imaged arid to create an image; and (c) acquiring a radiofrequency signal resulting from the object, so as to generate a magnetic resonance slice image of the object. The method provides slice selective multiple quantum magnetic resonance images of yet unprecedented quality in terms of contrast. The method is particularly useful for imaging connective tissues.

The present invention is directed to a radio-acoustic sounding system for providing wind measurements at altitudes of 100 meters or less. Wind measurements are obtained by transmitting a pulse of audio frequency energy through one or more volumes corresponding to the coverage area of one or more radio frequency transceivers. The frequency of the audio pulse is selected to have a wavelength that is one-half the wavelength of the electromagnetic energy transmitted by the antenna or antennas. By monitoring a return radio frequency signal at selected times following the transmission of the audio pulse, wind data is obtained at selected altitudes. Wind speed and direction can be obtained by observing the Doppler frequency shift of return radio frequency signals, or by observing the amplitude of the return radio frequency signals. In accordance with an embodiment of the present invention, precipitation measurements may be made by transmitting a radio frequency signal at the same radio frequency as is used in connection with wind measurements, and observing return radio frequency signals.

Disclosed is an RoF system providing an HD wireless communication service. The RoF system includes the base station for transmitting and receiving each of the TDD/FDD individual signals and TDD/FDD combined signals, channel-combining downstream signals for a TDD scheme with downstream signals for an FDD scheme, and generating TDD/FDD mode control signals; a base station donor for receiving downstream RF signals from the base station, converting the resultant signals into downstream optical signals, outputting the converted signals, and delivering upstream optical signals, which are input to the remote station from the wireless terminals, to the base station; and the remote station for switching a corresponding duplexing mode operation according to wireless service channel states of the wireless terminals, converting the downstream optical signals transmitted from the base station donor into service RF signals, amplifying the converted service RF signals, and providing the amplified service RF signals to the wireless terminals through antennas.

The invention provides a multi-standard multi-mode wireless transceiver, comprising an antenna, a radio-frequency receiver, a radio-frequency emitter, a frequency synchronizer, and a baseband processing circuit; the frequency synchronizer is used for generating at least two local oscillation signals required by modulation and demodulation and outputting the local oscillation signals to the radio-frequency receiver and the radio-frequency emitter; the antenna is a multi-frequency antenna which can respond toe a plurality of frequency signals; the radio-frequency receiver comprises a multi-frequency LNA which is connected with the antenna and used for responding to and increasing the radio-frequency signal intensity of a plurality of frequencies; the radio-frequency emitter comprises a multi-frequency PA which is connected with the antenna and used for responding to and amplifying the radio-frequency signal powers of a plurality of frequencies. The multi-standard multi-mode wireless transceiver is the wireless transceiver which can be applied to the worldwide range with a plurality of modes.

A repeater for re-transmitting an incoming RF signal comprising: a first antenna array for receiving the incoming RF signal; a second antenna array for transmitting an outgoing RF signal; and a transceiver for down-converting the incoming RF signal to a down-converted signal, processing the down-converted signal, and up-converting the processed signal to produce the outgoing RF signal. The first antenna array is cross-polarized with respect to the second antenna array. The repeater also comprises an echo processor for attenuating in the down-converted signal an echo signal associated with the outgoing RF signal. The echo processor delays transmission of the outgoing RF signal in order to minimize the echo signal.

The invention relates to an integrated circuit for contactless radiofrequency device connected to a first antenna and to a second antenna designed to receive a radiofrequency signal coming from a reader. According to a main characteristic, the integrated circuit includes a first rectifier circuit and a second rectifier circuit to rectify each radiofrequency signal received from the first antenna and the second antenna, respectively, so as to produce two positive output voltages V1 and V2, the rectifier circuits being mounted in parallel in order to select an output voltage value that corresponds to the maximum voltage value between V1 and V2.

A transmitting and receiving antenna VSWRs (voltage standing wave ratio) measuring circuit of a base station in a mobile communication system comprises: transmitting and receiving antennas for transmitting and receiving a radio frequency signal of a predetermined frequency band in a mobile communication system; transmitting antenna VSWR measuring means for variable-attenuating and detecting a transmitting signal received from the transmitting antenna and sending a transmitting signal strength to a measuring controller whereby to measure transmitting power and reflected power; and receiving antenna VSWR measuring means for variable-attenuating and detecting a receiving signal received from the transmitting antenna and sending a receiving signal strength to a measuring controller whereby to measure receiving power and reflected power.

Various embodiments of the present invention include methods and apparatus for receiving a radio frequency (RF) signal spectrum in a receiver; mixing the RF signal spectrum with a first local oscillator (LO) frequency to obtain a first downmixed signal; and converting the first downmixed signal to a first digital signal using an analog-to-digital converter (ADC) having an adjustable clock frequency selected to avoid interference with the first LO frequency. The adjustable clock frequency may be adjusted by a predetermined amount, by phase modulation, or in other manners.

A downconverter and upconverter are provided which can obtain a satisfactory image rejection ratio in a low-Intermediate Frequency (IF) scheme while reducing power consumption, and can improve Error Vector Magnitude (EVM) in a zero-IF scheme. A complex-coefficient transversal filter rejects one side of a positive or negative frequency, and converts a Radio Frequency (RF) signal to a complex RF signal configured by real and imaginary parts. A local oscillator outputs a complex local signal in which a set frequency is set as a center frequency. A full-complex mixer, connected to the complex-coefficient transversal filter and the local oscillator, perform a frequency conversion process by multiplying a complex signal output from the complex-coefficient transversal filter and the complex local signal output from the local oscillator, and outputs a complex signal of a frequency separated by the set frequency from a frequency of the RF signal.

A television tuner (920) is adapted for use in a television receiver (900) that receives a radio frequency (RF) signal from an input device (910) and outputs audio and video information from a selected channel in response thereto. The television tuner (920) includes a direct digital frequency synthesizer (206) and a mixer (220). The direct digital frequency synthesizer (206) has an output for providing a digital representation of a mixing signal. The mixer (220) has a signal input for receiving a television signal, a mixing input coupled to the output of said direct digital frequency synthesizer (206), and an output for providing an intermediate frequency (IF) television signal.

The invention relates to a fingerprint collection system comprising a fingerprint sensor, a scanning controller, a sensing unit driving circuit, an image output unit and a mode control circuit. The fingerprint sensor comprises a fingerprint sensing unit array, an antenna metal frame and a radiofrequency driving circuit; the fingerprint sensing unit array includes multiple sensing units, and the radiofrequency driving circuit drives the antenna metal frame to transmit radiofrequency signals. The scanning controller is used for selecting at least part of the sensing units of the fingerprint sensing unit array to serve as effective sensing units for sensing fingerprints and converting the same into electric signals. The sensing unit driving circuit is used for providing time-sequence signals needed for work of the effective sensing units. The image output unit is used for converting electric signals into digital fingerprint image information and outputting the information. The mode control circuit is used for controlling the sensing unit driving circuit to send different time-sequence signals to change working modes of the fingerprint collection system. The working modes at least include a capacitive collection mode and a radiofrequency collection mode. The fingerprint collection system has wide application range and has good collection and recognition effects in various application fields.

The invention provides a personnel detection and counting system based on a millimeter wave radar, wherein the millimeter wave radar is installed at a set position of a monitoring area, the millimeterwave radar transmits millimeter wave band radio frequency signals to the monitoring area through a multi-transmitting and multi-receiving antenna of the millimeter wave radar and receives echo signals at the same time, the echo signals are subjected to frequency mixing with the transmitted signals and then subjected to down-conversion to obtain beat intermediate frequency signals, and the beat intermediate frequency signals are sampled to obtain an echo sampling sequence. A digital signal processor reads the echo sampling sequence and performs signal processing to obtain a detected point cloud data set. An ARM processor reads the point cloud data set, meanwhile, Kalman filtering tracking is carried out on the point cloud data, continuous observation of states and the number of a pluralityof human body moving targets is achieved, the positions and the number of people in the monitoring area are obtained, and the number of people in the monitoring area is counted. The personnel detection and counting system based on the millimeter wave radar can track at least 20 targets simultaneously, provide the position and speed information of the targets, effectively judge the state of the targets and give early warning in time.

An radio frequency antenna assembly is provided for a medical device such as one capable of being implanted into a patient. The antenna assembly includes a plurality of antennas, each oriented to receive a radio frequency signal propagating along a different axis. This facilitates reception of the radio frequency signal regardless of the orientation of its propagation axis to the medical device. In other cases, the radio frequency signal has a plurality of components, each propagating along a different axis, and each antenna of the assembly receives a different one of those components. The individual electrical signals produced in each antenna are additively combined into a single signal having greater strength than each of the individual electrical signals.

The present invention provides a method and apparatus for multiplexing code division and frequency division transmissions. One embodiment of the method includes accessing at least one first symbol and at least one second symbol, encoding the at least one first symbol according to a frequency division protocol, and encoding the at least one second symbol using a coding sequence having a cyclic correlation property. The method also includes transmitting a radiofrequency signal indicative of the at least one encoded first symbol and the at least one encoded second symbol.

A system and method for implementing soft handoffs in a cellular communications system on a mobile platform. The system employs an antenna controller in communication with a beam forming network that generates two independently aimable lobes from a single beam. The single beam is radiated by a phased array antenna on the mobile platform. In an Air-to-Ground implementation involving an aircraft, a base transceiver station (BTS) look-up position table is utilized to provide the locations of a plurality of BTS sites within a given region that the aircraft is traversing. The antenna controller controls the beam forming network to generate dual lobes from the single beam that facilitate making a soft handoff from one BTS site to another. In a ground-based application, one lobe of the beam is used to maintain a communications link with one BTS site while a second lobe of the beam is continuously scanned about a predetermined arc to receive RF signals from other BTS sites and to determine when a new BTS site has become available that will provide a higher quality link than the link presently made with the one BTS site. A soft handoff is then implemented from the one BTS site to the new BTS site.

A system and method for implementing soft handoffs in a communications system on a mobile platform. The system employs an antenna controller in communication with a beam forming network that generates two independently aimable lobes from a single beam. The single beam is radiated by a phased array antenna on the mobile platform. In an Air-to-Ground implementation involving an aircraft, a base transceiver station (BTS) look-up position table is utilized to provide the locations of a plurality of BTS sites within a given region that the aircraft is traversing. The antenna controller controls the beam forming network to generate dual lobes from the single beam that facilitate making a soft handoff from one BTS site to another. In a ground-based application, one lobe of the beam is used to maintain a communications link with one BTS site while a second lobe of the beam is continuously scanned about a predetermined arc to receive RF signals from other BTS sites and to determine when a new BTS site has become available that will provide a higher quality link than the link presently made with the one BTS site. A soft handoff is then implemented from the one BTS site to the new BTS site.

Methods and apparatus are provided for mode diversity radio frequency identification (RFAID). The apparatus comprises a first transducer configured to receive a first radio frequency (RF) signal, a second transducer configured to receive an acoustic signal, and an impedance modulator coupled to the first transducer and the second transducer and configured to emit a signal identifying an RFAID tag when the first transducer receives the first RF signal and/or the second transducer receives the acoustic signal. The method comprises transmitting an RF signal and an acoustic frequency signal, and detecting a first modulated signal indicating an RFAID transponder. The first modulated signal is based on one of the RF signal and the acoustic signal.

A method for antenna subset selection by joint processing in RF and baseband in a multi-antenna systems. L_t input data streams are generated in a transmitter for either diversity transmission or multiplexing transmission. These streams are modulated to RF signals. These signals are switched to the t branches associated with the t transmit antennas, and a phase-shift transformation is applied to the RF signals by a t×t matrix multiplication operator Φ₁, whose output are t≧L_t RF signals. These signals are transmitted over a channel by t antennas. The transmitted signals are received by r antennas in a receiver. A phase-shift transformation is applied to the r RF signals by a r×r matrix multiplication operator Φ₂. L_r branches of these phase shifted streams are demodulated and further processed in baseband to recover the input data streams.

The invention discloses an electronic device and a signal processing method thereof. The method includes that a first signal pathway module in the electronic device receives radiofrequency signals through a main set of antennas and transmits the received radiofrequency signals to at least one radio frequency module for processing, or transmits at least one radiofrequency signals sent by the at least one radio frequency module and sends the radiofrequency signals through the main set of antennas; a second signal pathway module receives radiofrequency signals through a diversity antenna used by the second signal pathway module and sends the radiofrequency signals to at least one radio frequency module for processing; a GPS signal pathway module receives GPS signals through a GPS antenna used by the GPS signal pathway module and sends the GPS signals to at least one radio frequency module for processing; and at least one radio frequency module receives GPS signals through the GPS signal pathway module and at least one signal pathway module in the second signal pathway module. The influence of multipath effect of GPS signals on reception performance of the GPS signals on reception performance of GPS signals during reception of GPS signals.

The invention discloses a radiofrequency case suitable for testing base station radiofrequency index of a TD-SCDMA system, and a base station testing system and a method using the radiofrequency case. The radiofrequency case includes a radiofrequency switch, an attenuator, a mixer, an isolator, a circulator and a power divider. Signals from signal sources are inputted into the mixer via a radiofrequency signal inlet on the radiofrequency case and one path of the signal is performed attenuation treatment via the attenuator before it is inputted into the mixer; the radiofrequency signals treated by the mixer is inputted into a common port of the radiofrequency switch via the isolator and the circulator, and then is inputted into the base station via a switch connected with the common port; and meanwhile, the circulator receives downlink signals from the radiofrequency switch and isolates the uplink signals from the downlink signals, then the radiofrequency signals are multiplexed by the power divider and is outputted to a frequency spectrograph for performing radiofrequency index testing. The invention also discloses the base station testing system and the method based on the radiofrequency case. The invention has high automation degree and can achieve correct testing results.