Abstract: An antenna monitor collects statistics about the received signal strengths of each antenna in a cooperating antenna array over long periods of time. In cellular telephone base station applications for a base station using an array of antenna elements to obtain spatial diversity, samples of the received signal strength are taken during particular times whenever an active mobile subscriber is operating in the area. Periodically, such samples are averaged and added to a running total that is maintained in a long-term accumulator for each antenna. The accumulated totals are then compared after a statistically sufficient number of samples have been collected and averaged. Faulty antennas, including broken ones and ones with bad connections, will be revealed by those corresponding signal paths having relatively low accumulated totals. Given long enough collection periods, the spatial diversity of the antennas in the array will have only a minimal impact on favoring one antenna over another.

Abstract: A method operating in a communications station for calibrating the communications station, the communications station including an antenna array of antenna elements, each having associated with it and included in a transmit apparatus chain and a receiver apparatus chain. The method comprises transmitting a prescribed signal from each antenna element using the transmit apparatus chain associated with the antenna element while receiving the transmitted signal in receiver apparatus chains not associated with the antenna. Calibration factors for each antenna element are determined as dependent on the associated transmit apparatus chain and receiver apparatus chain transfer functions using the prescribed signal and each of the signals received during transmissions.

Abstract: A method and apparatus for generating a reference signal for use in an alternating projection loop which is part of demodulation in a base station of a wireless communication system, the reference signal relaxed to minimize the effects of frequency offset and amplitude variations, the base station including an array of antennas. The alternating projection loop demodulates in the presence of co-channel interference and includes correction for time alignment and/or frequency offset.

Abstract: An NMR system acquires data by performing a scan using a spin echo pulse sequence. An image is produced from the acquired data using a 2DFT reconstruction method. During the scan the echo time (TE) or the repetition time (TR) is altered as a function of phase encoding value to decrease total scan time or to improve signal-to-noise.

Abstract: An improved method for obtaining a multi-slice acquisition in which images from several slices are simultaneously acquired at preselected repetition times. One scan allows for the acquiring of images from multiple slices, at multiple repetition times TR and multiple echo times TE in such a manner that all available readout time is utilized when both the first repetition time TR1 and the second repetition time TR2 are both appropriate combinations of defined measurement intervals.