Abstract: Conventional adaptive equalizers often use the “sign/sign” algorithm as a low complexity means to adjust their tap weight coefficients by driving the correlation between its single-bit “error” and “data” signals to zero. This algorithm fails in the presence of strong residual intersymbol interference (ISI), since this ISI renders the “error” signal sufficiently inaccurate to mask the correlation between “data” and “error”. Failure manifests itself two-fold as an inability to achieve tap weight acquisition at startup, and an inability to track dynamic channel conditions. The invention described herein employs an adaptive estimator to compute the residual masking ISI terms that in turn control an adaptive error slicer to synthesize a modified single-bit “error” signal that remains correlated with the “data” signal.

Abstract: To accommodate for a release of uncleared spectrum in a wideband communication system (10) while improving isolation in a receiver (FIG. 4) between wideband carriers, a common intermediate frequency converter down-converts differing but relatively high frequency carriers, incident to the receiver, to corresponding differing but relatively low frequency carriers. Receiver chains (174-176) response to the plurality of relatively low frequency carriers each have a filter (140-144) arranged to isolate selected ones of the relatively low frequency carriers. In a radio frequency communication system having three or more frequency sequential carriers, the receiver chains (174-176) may include branches that have filters that further isolate carriers within the receiver by applying non-sequential carriers to the branches in each receiver chain.

Abstract: This invention relates to high power linear amplifiers. A high power linear amplifier is disclosed for communications such as CDMA communication systems. Linear amplifiers as used in communication systems exhibit a linear characteristic where the amplifiers output power increases relative to an input power. After a certain input level, known as a gain saturation point, the amplifier then exhibits non-linear characteristics; the output power increases relatively little with respect to power input. This non-linear region is also known as the saturation region or the gain compression region.

Abstract: A receiver for receiving a radio signal carrying digitally-encoded data has a plurality of diversity antennas, respectively coupled to inputs of a selector. A received signal selected by the selector is equalized by an adaptive equalizer and then demodulated to recover data, when possible. A quality metric dependent on the quality of the recovered data is generated. A switch controller responsive to the quality metric controls the selector. After the controller controls the selector to select a new antenna, it monitors the quality metric as the adaptive equalizer retrains and, if the quality metric does not exceed a predetermined threshold before a predetermined forward guard time expires, the controller causes the selector to select another antenna. The switch controller may also receive a signal level signal dependent on the level of the received signal.

Abstract: A control arrangement and method for controlling a gain and phase adjuster used for controlling the gain and phase of a compensation signal for compensating for the distortion produced by a power amplifier is disclosed. The control arrangement makes use of a reference signal, of known frequency, which is amplified along with the desired carrier signals. The reference signal component of the amplified signal is then isolated and a comparison is made, either with the actual reference signal, e.g., by a QAM demodulator, or alternatively with the known frequency of the reference signal, e.g., by a FM discriminator, in order to determine the differences in gain and in phase of the reference signal component of the amplified signal in comparison with the reference signal. For example, a QAM demodulator is used for producing a first difference signal indicative of the phase switch difference, and a second difference signal indicative of the gain switch difference.