Abstract: An apparatus is provided. In the apparatus, an input to index (I2I) module maps a complex input into a real signal. A real data tap delay line is coupled to the I2I module and includes N delay-elements. A complex data tap delay line is configured to receive the complex input and includes M delay elements. A set of K of non-linear function modules is also provided. Each non-linear function module from the set has at least one real input, at least one complex input, and at least one complex output. A configurable connectivity crossbar multiplexer couples K of the N real tap delay line elements to real inputs of the set non-linear functions and couples K of the M complex tap delay line elements to complex inputs of the set non-linear function modules.

Abstract: A method of performing overlap-and-add length for zero-padded suffixes. The method includes derotating received information symbol samples. The derotated received information symbol samples include a first set of derotated received information symbol samples and a second set of derotated received information symbol samples. The first set of derotated received information symbol samples are stored in a buffer. The second set of derotated received information symbol samples are provided to a received sample processing unit. The received zero-padded suffix samples are deroted. Based upon an overlap-and-add length, at least a fraction of the derotated received zero-padded suffix samples is added with at least a fraction of the first set of derotated received information symbol samples to produce multiple summed samples. The multiple summed samples is provided to the received sample processing unit.

Abstract: Systems and methods for power amplifier pre-distortion are provided. The systems and methods of power amplifier digital pre-distortion disclosed herein may include a generic pre-distorter architecture which can implement a variety of Volterra cross terms involving single dimension convolutions (first order dynamics). For hardware implementations, this generic pre-distorter is further fine-tuned to provide a choice between different sets of cross terms that can be selected for a given PA for optimal performance. The novel pre-distorter architecture provides flexibility to trade off memory depth for additional Volterra terms and vice versa. A further novelty is the ability to trade off both memory depth and cross terms for a higher sample rate operation, which may enable higher order non-linear pre-distortion, or support for higher signal bandwidths. A poly-phase non-linear filtering mode allows for this flexibility.

Abstract: A system and method of flexible channel allocation in an ultra wideband frequency hopping communication system is disclosed. In one embodiment, a method includes communicating radio signals through rapidly switching among a band group 6 according to a hopping pattern. The method also includes scanning the ultra wideband spectra to determine the band group 6 based on the hopping pattern of the radio signals. In another embodiment, a method includes scanning ultra wideband spectra to eliminate any frequency band of the ultra wideband spectra from a list of available frequency bands when the any frequency band is currently used, selecting a band group in combination of two or more frequency bands to communicate radio signals with an optimal transmission power and/or maximum range, and communicating the radio signals through rapidly switching among the band group.

Abstract: A method of adjusting overlap-and-add length for zero-padded suffixes. The method includes, based on a channel impulse response, estimating an effective channel length. When the effective channel length is less than a default overlap-and-add length and greater than a minimum length, the method includes setting the overlap-and-add length to the effective channel length. When the effective channel length is less than the minimum length, the method includes setting the overlap-and-add length to the minimum length. When the effective channel length is greater than the default overlap-and-add length, the method includes setting the overlap-and-add length to the default overlap-and-add length.

Abstract: A method of adjusting overlap-and-add length for zero-padded suffixes. The method includes, based on a channel impulse response, estimating an effective channel length. When the effective channel length is less than a default overlap-and-add length and greater than a minimum length, the method includes setting the overlap-and-add length to the effective channel length. When the effective channel length is less than the minimum length, the method includes setting the overlap-and-add length to the minimum length. When the effective channel length is greater than the default overlap-and-add length, the method includes setting the overlap-and-add length to the default overlap-and-add length.

Abstract: A system and method of flexible channel allocation in an ultra wideband frequency hopping communication system is disclosed. In one embodiment, a method includes communicating radio signals through rapidly switching among a band group 6 according to a hopping pattern. The method also includes scanning the ultra wideband spectra to determine the band group 6 based on the hopping pattern of the radio signals. In another embodiment, a method includes scanning ultra wideband spectra to eliminate any frequency band of the ultra wideband spectra from a list of available frequency bands when the any frequency band is currently used, selecting a band group in combination of two or more frequency bands to communicate radio signals with an optimal transmission power and/or maximum range, and communicating the radio signals through rapidly switching among the band group.

Abstract: Known antenna array manifold information is exploited to provide for fast and accurate channel estimation and demodulation on both the forward and reverse links, thereby increasing capacity in PCS and cellular CDMA networks that use adaptive antenna arrays. On the reverse link, an “extended” array manifold is used to assist the demodulator in maintaining a dynamic estimate of the spatial signature to use for beamforming and coherent demodulation. On the forward link, channel estimation is performed in the handset to provide a robust solution for beamforming.

Abstract: An adaptive filter for use in disk drive systems includes coefficient adaptation circuitry operating at a slower rate than the filter and consequently at a reduced power level. The adaptive filter receives input data samples corresponding to raw data read from a disk in the disk drive system and converted to digital form and provides processed output data samples. The action of the filter is defined by characteristic filter coefficients having values that are updated by adaptation circuitry during the operation of the filter. The adaptive filter is independently clocked from the adaptation circuitry, such that the input data samples and the processed output data samples are clocked through the adaptive filter at a clock rate 1/T, and the filter coefficients are updated according to a prescribed algorithm at an update rate slower than the 1/T clock rate. Filter coefficient updating occurs preferably at a rate equal to 1/J, where J is an integer greater than unity and generally in the range of 2 to 8.

Abstract: Adaptive decision feedback equalizer apparatus for processing information stored on disk or tape media or the like including a data input buffer (34), a gain acquisition circuit (42), a timing acquisition circuit (40) operative to generate timing error signals for controlling the sampling phase of the read signals input to the input buffer, a synchronizing circuit (44) for generating sync detect signals and polarity signals, an FIR filter (36) for generating linear filter output signals, register means (39), feedforward update logic (38) for adjusting the equalizer coefficient signals to develop updated coefficient signals, a dual ported RAM (50) for storing a plurality of the equalizer coefficient signals, feedback logic (48) responsive to the linear filter output signals, equalizer coefficient signals obtained from the RAM, and train data signals, and operative to compute the equalizer error signals and equalizer output signals, feedback update logic (52) for adjusting the values of the coefficient signals

Abstract: A class IV partial response, maximum likelihood data channel for a disk drive includes an encoder connected to a data sequencer for converting user data blocks into a predetermined 8/9ths code such as a (0,4,4,) code. A precoder conveys the 8/9ths code into class IV code. An analog write driver supplies the class IV code to a data transducer head during data write-to-disk operations. A read channel connected to the head amplifies and conditions analog signals during data read operations. A quantizer produces samples of the analog signals in accordance with a quantization clock generated by a clock generator. An adaptive FIR filter means is conditions the data samples in accordance with selectable, adaptive filter coefficients. A Viterbi detector puts out the class IV code from the filtered and quantized samples. A postcoder conveys the detected class IV code into detected 8/9ths code. A decoder converts the detected 8/9ths code into user data and supplies user data to the sequencer.

Abstract: A digital adaptive finite impulse response filter circuit is provided for a PR4,ML sampled data channel including an analog to digital sampler for providing raw digital samples of data to the filter circuit and a sampled data detector for detecting coded data from conditioned digital samples received from the filter circuit. The filter circuit comprises a multi-tap transversal filter structure wherein each tap is connected to receive a selected coefficient, a source of a plurality of coefficients for each tap, a coefficient selector connected to the source to receive the plurality of coefficients and to provide a selected coefficient to each tap of the transversal filter structure, and a control circuit for controlling the coefficient selector and the source for providing each of the selected coefficients to a corresponding tap of the transversal filter structure. Training and adaptation methods and circuits for adapting the filter structure are also described.

Abstract: A multi-mode gain control loop for a PR4, ML data channel, such as one included in a magnetic disk data storage device, includes an input for receiving from a source an analog signal stream including coded data to be detected; a VGA for amplifying the analog signal stream; an analog to digital converter for receiving the analog signal stream and for generating and putting out data samples therefrom; an analog gain control loop connected to generate an analog gain control from the analog data stream during a data non-read mode of the channel, to store the analog gain control in a storage circuit, and to apply the stored analog gain control constantly to control the VGA; and a digital gain control loop connected to generate gain vernier correction values from the data samples and for applying the gain vernier correction values through a gain DAC to provide an offset control to the VGA during a data read mode of the channel.

Abstract: A class IV partial response, maximum likelihood data channel for a disk drive includes an encoder connected to a data sequencer for converting user data blocks into a predetermined 8/9ths code such as a (0,4,4,) code. A precoder converts the 8/9ths code into class IV code. An analog write driver supplies the class IV code to a data transducer head during data write-to-disk operations. A read channel connected to the head amplifies and conditions analog signals during data read operations. A quantizer produces samples of the analog signals in accordance with a quantization clock generated by a clock generator. An adaptive FIR filter means is conditions the data samples in accordance with selectable, adaptive filter coefficients. A Viterbi detector puts out the class IV code from the filtered and quantized samples. A postcoder converts the detected class IV code into detected 8/9ths code. A decoder converts the detected 8/9ths code into user data and supplies user data to the sequencer.

Abstract: A class IV partial response, maximum likelihood data channel for a disk drive includes an encoder connected to a data sequencer for converting user data blocks into a predetermined 8/9ths code such as a (0,4,4,) code. A precoder converts the 8/9ths code into class IV code. An analog write driver supplies the class IV code to a data transducer head during data write-to-disk operations. A read channel connected to the head amplifies and conditions analog signals during data read operations. A quantizer produces samples of the analog signals in accordance with a quantization clock generated by a clock generator. An adaptive FIR filter means is conditions the data samples in accordance with selectable, adaptive filter coefficients. A Viterbi detector puts out the class IV code from the filtered and quantized samples. A postcoder converts the detected class IV code into detected 8/9ths code. A decoder converts the detected 8/9ths code into user data and supplies user data to the sequencer.

Abstract: A digital peak detection circuit asynchronously detects embedded overhead information such as servo or sync pattern data within a PR4,ML synchronous data detection channel of a magnetic disk drive. The channel includes an analog to digital converter clocked by a data clock operating asynchronously with respect to playback of the embedded overhead information in the channel for converting an analog data stream into raw data samples, and an adaptive digital FIR filter for conditioning the raw data samples into conditioned data samples in accordance with programmable filter coefficients.

Abstract: A multi-mode timing loop for a PR4,ML sampled data channel includes an analog to digital converter and a digital finite impulse response filter for providing conditioned digital samples. The timing loop includes a reference clock source for putting out a reference clock frequency related to a nominal sample data rate, a frequency controllable oscillator connected to generate a sample clock, an analog timing loop and a digital timing loop. The analog timing loop provides phase lock during non-data read mode, and during data read mode the digital timing loop provides a vernier offset for fine adjustment of phase lock to a static setting then provided by the analog timing loop.

Abstract: Adaptive decision feedback equalizer apparatus for processing information stored on disk or tape media or the like including a data input buffer (34), a gain acquisition circuit (42), a timing acquisition circuit (40) operative to generate timing error signals for controlling the sampling phase of the read signals input to the input buffer, a synchronizing circuit (44) for generating sync detect signals and polarity signals, an FIR filter (36) for generating linear filter output signals, register means (39), feedforward update logic (38) for adjusting the equalizer coefficient signals to develop undated coefficient signals, a dual ported RAM (50) for storing a plurality of the equalizer coefficient signals, feedback logic (48) responsive to the linear filter output signals, equalizer coefficient signals obtained from the RAM, and train data signals, and operative to compute the equalizer error signals and equalizer output signals, feedback update logic (52) for adjusting the values of the coefficient signals

Abstract: A wheeled, portable, equipment-carrying and camera-mounting cart is provided which is both highly stable and collapsible into a highly compact configuration. The cart comprises a frame having a pair of wheels and camera-mounting monopod offset forwardly of the axis of the wheels, with a selectively extensible and retractable ground-engaging leg assembly which, when extended, forms a regular polygonal stabilizing base in conjunction with the wheels, the monopod being centrally positioned with respect to the polygon. Equipment-supporting surfaces and enclosure members are provided for permitting the user to carry equipment protectively on the cart even when in its collapsed condition.