40 results about "Multipath reception" patented technology

A system is presented for the multipath reception of video signals, including sound an / or image signals. The system includes at least two receivers and a diversity unit. At least one receiver receives and processes analog video signals, while the one or more remaining receivers receive and process digital video signals. The system may further include an analog selector unit for selecting the highest quality analog signal, and / or a digital selector unit for selecting the highest quality digital signal. The diversity unit receives the processed analog and digital video signals and combines them to produce a resulting video signal having a quality at least as high as the better of the processed analog and digital video signals. The diversity unit may combine the received video signals by performing a weighted addition of the signals.

The diversity unit consists of antenna unit containing two routes of antenna channels, signal selector including antenna selection switch and switch for selecting receiving and transmitting, transceiver unit including a receiver and a transmitter, and signal selection / control interface including RSSI module for testing intensity of received signal. One route of receiver and transmitter, and antenna in multipath reception and transmission are utilized in the device. Using switch in radio frequency for switching selections among multiple channels of antenna provides control interface, and strobing one route of antenna as receiving and transmitting channel. Same channel is adopted for receiving and transmitting signal in order to keep balance of chain. In TDD mode, receiving signal and transmitting signal are positioned at different time slots. Switch in radio frequency makes receiving signal and transmitting signal possible to use same antenna channel, and balance the chain.

A micropatch antenna system with simultaneous high bandwidth and low sensitivity to multipath radiation is achieved by positioning a radiating element within a cavity in a ground plane. Bandwidth and sensitivity to multipath radiation may be varied by varying the height of the radiating element above the bottom of the cavity and above the top of the ground plane. The electromagnetic and physical characteristics of the antenna system may be further controlled by introducing dielectric solids or wave-slowing structures between the bottom of the cavity and the radiating element. A dual-band micropatch antenna system with simultaneous high bandwidth and low sensitivity to multipath radiation may be similarly configured by stacking a second radiating element on top of the first radiating element.

A ground plane for reducing multipath reception comprises a convex conducting surface and an array of conducting elements disposed on at least a portion of the convex conducting surface. Embodiments of the convex conducting surface include a portion of a sphere and a sphere. Each conducting element comprises an elongated body structure having a transverse dimension and a length, wherein the transverse dimension is substantially less than the length. The cross-section of the elongated body structure can have various user-specified shapes. Each conducting element can further comprise a tip structure. The azimuth spacings, lengths, and surface densities of the conducting elements can be functions of meridian angle. An antenna can be mounted directly on the conducting convex surface or on a conducting or dielectric support structure mounted on the conducting convex surface. System components, such as a navigation receiver, can be mounted inside the conducting convex surface.

To provide an apparatus which reduces the scale of a reception circuit and the power consumption as the tracking function of tracking phase jitter of the multipath propagation route. A RAKE reception apparatus includes a plurality of finger circuits for receiving signals spectrum-spread by spread codes, despreading respective reception signals retrieved by a searcher adapted for retrieving respective paths from multipath reception signals for demodulating the signals, and a RAKE combiner for combining outputs of the plural finger circuits. Each of the plural finger circuits is provided with one DLL circuit without being provided with an inner DLL circuit. The finger circuits to be tracked by the DLL circuit are switched by a changeover circuit. There is provided a control circuit for controlling the changeover circuit based on the weighting information for each finger circuit to be found by the RAKE combiner for sequentially selecting the finger circuits to be tracked by the DLL circuit.

An FM tuner that has a multipath reception detection unit and an adjacent-channel interference detection unit while reducing expansion of the scale of the circuit is available. A control signal for a stereo separation level is generated on the basis of a signal SM-DC corresponding to a reception field strength and of a signal SMP corresponding to a multipath noise component. The SMP is extracted from a fluctuation component signal SM-AC from an S-meter circuit 92 by a multipath noise extraction circuit 104. The multipath noise extraction circuit 104 used for control of the stereo separation level is shared as a portion of the circuitry for detecting the multipath signal reception state. A multipath reception detection unit 108 compares the SMP with a threshold value to detect a multipath reception state.

An FM tuner that has a multipath reception detection unit and an adjacent-channel interference detection unit while reducing expansion of the scale of the circuit is available. A control signal for a stereo separation level is generated on the basis of a signal SM-DC corresponding to a reception field strength and of a signal SMP corresponding to a multipath noise component. The SMP is extracted from a fluctuation component signal SM-AC from an S-meter circuit 92 by a multipath noise extraction circuit 104. The multipath noise extraction circuit 104 used for control of the stereo separation level is shared as a portion of the circuitry for detecting the multipath signal reception state. A multipath reception detection unit 108 compares the SMP with a threshold value to detect a multipath reception state.

Multipath reception by an antenna is reduced by mounting the antenna on a semi-transparent ground plane that has a controlled distribution of layer impedance over a central region and a peripheral region. The central region includes a continuous conductive segment on which the ground element of the antenna is disposed. The distribution of the layer impedance over the peripheral region is configured by multiple conductive segments electromagnetically coupled by lumped circuit elements. A semi-transparent ground plane can be fabricated by depositing a metal film on a dielectric substrate and etching grooves into the metal film to form a desired pattern of conductive segments. Lumped circuit elements can be fabricated as discrete devices, surface mount devices, and integrated circuit devices. Various semi-transparent ground planes can be configured for linearly-polarized and circularly-polarized radiation.

Patch antennas for signals of global navigation satellite systems (GNSS) are described. A compact antenna system reduces directional diagram level in the rear hemisphere primarily for cross-polarized (left hand circularly-polarized) component. It can be used for reducing multipath reception. The antenna receives GNSS signals and includes a patch circularly-polarized radiator consisting of a radiating patch, a ground plane under it and a loop radiator coaxially located around the patch radiator. The loop radiator is excited by a separate power circuit or by a passive method where LHCP waves of MP and loop radiators in the rear hemisphere would be anti-phase added. A dual-band antenna system includes an active HF radiator, under which there is an active LF radiator under which there is a passive LF radiator, a loop HF radiator being coaxially located around the active HF radiator.

An antenna system for a global navigation satellite system reference base station is disclosed.The antenna system includes an antenna positioned above a high capacitive impedance surface (HCIS) ground plane.Over a specific range of the lateral dimension of the HCIS ground plane and the height of the antenna above the HCIS ground plane, a high level of multipath suppression and high sensitivity for low-elevated satellites can be simultaneously maintained.The HCIS ground plane can be fabricated as a flat conducting plate with an array of conducting elements such as pins, pins with expanded tips, or mushroom structures. Alternatively, the HCIS can be fabricated as a flat conducting plate with a concentric series of choke rings.The antenna system can provide a positioning accuracy of + / −1 mm, an order of magnitude improvement over previous designs.

An antenna system for global navigation satellite systems includes a ground plane, an active antenna disposed above the ground plane, and a passive antenna disposed below the ground plane. The active antenna includes a conducting ring substantially parallel to the ground plane. A radiating conductor passes through substantially the center of the conducting ring; the ends of the radiating conductor are electrically connected to the conducting ring. An excitation pin is electrically connected to the radiating conductor. A set of reactive impedance elements is electrically connected between the conducting ring and the ground plane. The set of reactive impedance elements is disposed substantially orthogonal to the ground plane. The passive antenna is similar to the active antenna, except the passive antenna does not have an excitation pin. The antenna system effectively suppresses multipath reception, and its compact size and light weight make it suitable for integration with a surveying pole.

The invention provides a code division multiple access (CDMA) secure coding and decoding method and system, and the CDMA secure coding method comprises the steps: receiving a first clock signal, and converting the first clock signal into an analog signal; receiving a data signal and a second clock signal, and performing differential double-phase coding on the data signal to obtain a coded digital signal; conditioning and amplifying the analog signal, and coupling the analog signal with the coded digital signal to obtain a required baseband signal; coding the baseband signal to obtain a baseband coded signal; and performing CDMA coding on the baseband coding signal to obtain a CDMA coding signal. According to the CDMA safe coding and decoding method and system, interconnection and intercommunication of European railway operation control systems can be met, and the problems that an existing European train operation control system is poor in anti-interference performance, only suitable for short-distance transmission, high in bit error rate, high in receiving sensitivity threshold, free of multipath receiving and the like due to the fact that FSK, PSK and other signal systems are adopted are solved.

An antenna is configured to operate with circularly-polarized electromagnetic radiation in a low-frequency band and in a high-frequency band. The antenna comprises a ground plane and a radiator. The radiator comprises four pairs of radiating elements disposed as pairs of spiral segments on a cylindrical surface having a longitudinal axis orthogonal to the ground plane. Each pair of radiating elements comprises a low-frequency radiating element and a high-frequency radiating element. The low-frequency radiating element comprises a low-frequency conductive strip. The high-frequency radiating element comprises an electrically-connected series of at least one high-frequency conductive strip and at least one high-frequency capacitor. The electrical path lengths of the low-frequency radiating elements and the electrical path lengths of the high-frequency radiating elements are equal.

An antenna system for a global navigation satellite system reference base station is disclosed. The antenna system includes an antenna positioned above a high capacitive impedance surface (HCIS) ground plane. Over a specific range of the lateral dimension of the HCIS ground plane and the height of the antenna above the HCIS ground plane, a high level of multipath suppression and high sensitivity for low-elevated satellites can be simultaneously maintained. The HCIS ground plane can be fabricated as a flat conducting plate with an array of conducting elements such as pins, pins with expanded tips, or mushroom structures. Alternatively, the HCIS can be fabricated as a flat conducting plate with a concentric series of choke rings. The antenna system can provide a positioning accuracy of + / −1 mm, an order of magnitude improvement over previous designs.

The diversity unit consists of antenna unit containing two routes of antenna channels, signal selector including antenna selection switch and switch for selecting receiving and transmitting, transceiver unit including a receiver and a transmitter, and signal selection / control interface including RSSI module for testing intensity of received signal. One route of receiver and transmitter, and antenna in multipath reception and transmission are utilized in the device. Using switch in radio frequency for switching selections among multiple channels of antenna provides control interface, and strobing one route of antenna as receiving and transmitting channel. Same channel is adopted for receiving and transmitting signal in order to keep balance of chain. In TDD mode, receiving signal and transmitting signal are positioned at different time slots. Switch in radio frequency makes receiving signal and transmitting signal possible to use same antenna channel, and balance the chain.

The invention relates to the technical field of wireless networks, and discloses a method for rapidly finding a multi-hop mobile wireless self-organizing network topology. The method includes the following steps: a node A in a whole network structure broadcasting state information thereof; all first hop neighbor nodes receiving the state information, analyzing the state information and forwarding the state information to second hop neighbor nodes; using the multi-path receiving method, the second hop neighbor nodes simultaneously receiving the state information of the node A concurrently transmitted by the first hop neighbor nodes and analyzing the state information, forwarding the analyzed state information of the node A to a next hop neighbor node; repeating the procedures, using the multi-path receiving method, the N hop neighbor nodes simultaneously receiving the state information of the node A concurrently transmitted by N-1 hop neighbor nodes and analyzing the state information, forwarding the analyzed state information of the node A to a next hop neighbor node until the state information spreads to the whole network, using TDMA mechanism to configure information channel resources when the state information of the node A is spread to the whole network. The method achieves rapid finding of the mobile wireless self-organizing network topology.

The invention discloses a large-scale-MIMO based multi-user uplink frequency synchronization method. A base station terminal in the method has a large scale uniform antenna array, and a multi-user terminal performs frequency synchronization through a base station reception antenna under uplink OFDM modulation. Since an incident signal sent by each user to the base station is limited to a narrow angle range under the influence of multipath, carrier frequency offset estimation and compensation are performed for each user using a joint space-frequency alignment method. In the invention, thanks to the spatial degree of freedom provided by the large-scale antenna array, a steering vector corresponding to the corresponding qualified direction of arrival of each user is used to perform reception wave beam formation to enable multi-user interference to be effectively suppressed. The multipath reception wave beam formation method makes an equivalent single-user transmission model form between each user and the base station, so that traditional single-user channel estimation and data detection technology can be used.

This disclosure relates to techniques for efficient reordering of data packets in multipath scenarios. In particular, the present disclosure relates to a reordering queue device (701) for a multipath receiver (700), the reordering queue device (701) comprising: a reordering queue (230), the reordering queue (230) configured to queue sequentially numbered data packets (208, 209, 210) received on a plurality of paths (223) of a multipath channel; and reordering the queue a controller (702), the reordering queue controller (702) configured to reorder the data packets (208, 209, 210) in the reordering queue (230) according to a reordering criterion (703), wherein the The reordering criterion (703) is based on at least one of: a path-specific sequence number (400) of the data packet (208, 209, 210), an overall sequence number comparison (500) across the plurality of paths (223) . Path-specific characteristics (600) of the plurality of paths (223), in particular latency.

An antenna system includes a right-hand circularly polarized antenna for receiving Global Navigation Satellite System (GNSS) signals and located on a receiver housing; a vertical semitransparent screen for providing an Down / Up ratioDU9⁢0=DU⁡(θe=9⁢0∘)=F⁡(-9⁢0∘)F⁡(9⁢0∘)of −13 dB or better for at least some GNSS frequencies; the semitransparent screen being connected to a ground plane of the antenna; the ground plane being connected to a conductive receiver housing; the semitransparent screen further comprising a horizontal slot to which sets of lumped impedance elements are connected. Each set includes several lumped elements; where the lumped elements are capacitors and / or inductors and / or resistors; where the lumped elements in each set are connected in parallel or series; and the semitransparent screen including at least 4 segments arranged symmetrically around the center of the antenna and connected to each other.