Transmit and/or receive diversity is achieved using multiple antennas. In some embodiments, a single transmitter chain within a wireless terminal is coupled over time to a plurality of transmit antennas. At any given time, a controllable switching module couples the single transmitter chain to one the plurality of transmit antennas. Over time, the switching module couples the output signals from the single transmitter chain to different transmit antennas. Switching decisions are based upon predetermined information, dwell information, and/or channel condition feedback information. Switching is performed on some dwell and/or channel estimation boundaries. In some OFDM embodiments, each of multiple transmitter chains is coupled respectively to a different transmit antenna. Information to be transmitted is mapped to a plurality of tones. Different subsets of tones are formed for and transmitted through different transmit chain/antenna sets simultaneously. The balance of tones allocated to the subsets for each antenna are changed as a function of predetermined information, dwell information, and/or channel condition feedback information.

Methods and apparatus of providing transmit and/or receive diversity with multiple antennas in wireless communication systems

A system for continuously and precisely measuring the positions of a generally symmetrical object, eg, a tennis ball, in motion in a predefined three-dimensional region, eg, a tennis court (300), which transmits multiple radar signals from first, second, and third, spaced antenna devices (200, 202, 204 etc), respectively, into the three-dimensional region Multiple return signals are sensed and are compared with the transmitted signals to determine the phases of the return signals, to thereby obtain ambiguous ranges of the object Ambiguities are removed by using the Chinese Remainder Theorem to obtain less-ambiguous ranges A mathematical model defining boundaries of the three-dimensional region is completed by placing signal reflector devices (320-325) on various boundary points of the three-dimensional region, and transmitting the radar signals when the object is not in the three-dimensional region Further, the return signals are processed to obtain an initial survey of the region and then to periodically resurvey the region, for calibration of the system

Method and apparatus for radar measurement of ball in play.

Target tracking capability is provided by a synergistic tracker system (5) which includes both a correlation tracker (30) and an object tracker (40) for processing sensor data input (10) and for generating tracking error signals (80). The operation of the synergistic tracker system is controlled by a central processing unit (70). The system operates by first correlating a reference region image with a portion of a current digitized image provided by an analog to digital converter (20). Secondly, the object tracker provides a precisely defined trackpoint for an object within the current image. The correlation tracker stabilizes and limits the portion of the digitized image that the object tracker must operate upon. Stabilizing and limiting this portion of the digitized image reduces the object tracker's sensitivity to background clutter and sensitivity to a loss of lock induced by sensor motion. The object tracker provides a non-recursive update for the correlation's reference region image. The correlation tracker and the object tracker are used simultaneously and cooperatively so that the strengths of one tracker are used to overcome the weaknesses of the other. A method of tracking a target immersed in background clutter is also disclosed.

Apparatus and method for tracking a target

A dual waveband signal processing system (DWSPS) is disclosed for differentiating between an primary target signal and background clutter to detect targets and objects with a particularly unique spectral characteristic. The DWSPS is responsive to a plurality of sensors operating on different wavelengths. The output wavebands of the sensors are filtered by either spatial or temporal high-pass filters, and is processed through a network comprising a series of multipliers, dividers, comparators, and subtractors to obtain the weighted correlation functions or "alpha coefficient", which, when compared to the input wavebands, produces a filtered or processed output signal of the detected features.

Dual waveband signal processing system

An accumulated statistics CFAR method and device operates using integrated data to maximize the probability of target detection for a given false alarm rate. The CFAR hardware varies its detection criteria as a function of the statistics of the range gate in question. The detection threshold is based on other range gates seen in the past which contain the same terrain type.

Accumulated statistics constant false alarm rate method and device

A five stage background filter circuit (10) which is capable of responding to background radiation changes at speeds which are from one to two orders of magnitude faster than conventional prior filter. The invention utilizes a cross can multiplexing technique in combination with filter circuitry depicted in schematic over view in (Fig. 1). Circuit (10) includes a differential amplifier (12), a sample and hold device (14), a responsivity corrector (16), a recursive filter (18), and a background subtractor (20). Output signals (11) from a focal plane array of detectors (Fig. 3) are passed through impedance matching input resistors (12a, b) to an amplifier. A sample and hold circuit (14a) cyclically selects and stores a signal received from first stage (12). The detector outputs are then normalized by responsivity corrector stage (16) which employs a digital-to-analog converter (16a) and random access memory (16c). A threshold band comparison and time-out logic circuit (21) within background subtractor stage (20) controls the operation of recursive filter stage (18) in order to suppress signals due to sensed radiation bursts and to eliminate the unwanted, dynamically varying background radiation portion of the signal present at node (17b). A processed output signal present at node (20i) is then passed to a target detection processor.

Richard L Hedden

Papers

Extremely high speed, real-time background filter for radiation detectors