Zarbana Digital Fund LLC

Other

Pmc-sierra Us, Inc.

Microsemi Storage Solutions (u.s.), Inc.

Icefyre Semiconductor Corporation

Aryan Saed

Phil Guillemette

On-chip at-speed eye measurements of digitized signals in data and timing recovery circuits are disclosed. Eye diagrams and jitter measurements are used to evaluate signal quality and bath-tub Bit Error Rate characteristics in baseband communication systems. This disclosure describes a method and apparatus for digitally sampling a received signal at speed to produce an eye diagram of the received signal. This involves adding a small amount of circuitry to the existing prior art systems that use an interpolator for timing recovery and data recovery. In the present disclosure a temporary offset is applied to the interpolation index of the interpolator to obtain interpolated samples between the baud center and baud edge. The eye diagram can be produced from the received digitized and interpolated signal before equalization, or alternatively from the equalized signal.

Measuring impairments of digitized signals in data and timing recovery circuits

A method of measuring signal impairments is disclosed for use in an asynchronous Digital Signal Processing (DSP) based data and timing recovery circuit including an interpolator circuit. The method includes: calculating amplitude values for data and timing recovery; calculating an interpolation index for the interpolator circuit; and overriding the interpolation index. In another implementation, a method of measuring signal impairments in an asynchronous DSP-based data and timing recovery circuit including an interpolator circuit includes: calculating amplitude values for data and timing recovery; calculating a timing control signal; and overriding the timing control signal.

Methods and systems to generate control signals for timing recovery of a signal received over baseband communications systems are disclosed. The timing control circuit uses a multi-rate DSP structure for the implementation of the DSP functions in the control loop for use in an ASIC and requires a reduced DSP clock rate, which in turn reduces the need for pipelining and/or high-speed libraries. Thus lower latency, better tracking performance and lower power consumption are achieved. An example embodiment involves splitting the timing error signal, supplied at a given update rate, into a sum and a difference component, and processing each component in separate circuit chains at half the update rate. The resultant half-rate control signals from each separate circuit chain are joined to provide a control signal at the full update rate. Thus, implementations of the present disclosure perform like a full-rate structure, but require a halved DSP clock rate.

Multi-rate control loop for a digital phase locked loop

A mosaic movie resembling a target movie is composed of movies from a data base. The target movie is divided into tile regions of a specified size and shape, and the individual movies from the data base are compared to each region to find the best matching tile. The comparison is performed by calculating a figure of visual difference between each tile and each region. The data base of tile images is created from raw source movie using digital image processing, whereby multiple instances of each individual raw source movie are produced. Tile matching is performed such that all raw source movies are represented in the final mosaic. The digital image processing involves the adjustment of colour, brightness and contrast of tile movies, as well as cropping. A movie description index locates each movie in the final mosaic.

Digital composition of a mosaic motion picture

Systems, methods, and devices relating to the provision of deliberate predistortion to an input signal to compensate for distortions introduced by an amplifier subsystem. An input signal is received by a signal processing system which includes a predistortion subsystem. The input signal is decomposed and the fragments are then predistorted by the predistortion subsystem by applying a deliberate predistortion to the fragments. The predistorted fragments are then separately processed and recombined to arrive at the system output signal. The predistortion subsystem adaptively adjusts based on characteristics of the system output signal. Also, the predistortion subsystem is equipped with a control system that is state based&#x2014;the state of the predistortion subsystem is dependent upon the prevailing conditions and, when required, the control system switches the state of the predistortion subsystem. A feedback signal, a replica of the system output signal, is used in updating lookup table entries used to determine the predistortion.

Adaptive predistortion for a transmit system

The present invention provides a digital (computational) branch calibrator which uses a feedback signal sensed from an RF transmit signal path following the combining stage of LINC circuitry of a transmitter to compensate for gain and phase imbalances occurring between branch fragment signals leading to the combiner. The calibrator feeds a quiet (zero) base band signal through the transmit path during the calibration sequence (i.e. a period when data is not transmitted) and adjusts the phase and gain of the phasor fragment signals input thereto by driving the sensed output power to zero. The calibration is performed by alternating phase and gain adjustments with predetermined (programmable) and multiple update parameters stages (speeds). A baseband modulation is preferably used to distinguish false leakage (e.g. due to local oscillator, LO, feed through and DC offset in the base band Tx) from imbalance leakage.

Digital branch calibrator for an RF transmitter

Systems and methods related to amplifier systems which use a predistortion subsystem to compensate for expected distortions in the system output signal. A signal processing subsystem receives an input signal and decomposes the input signal into multiple components. Each signal component is received by a predistortion subsystem which applies a predistortion modification to the component. The predistortion modification may be a phase modification, a magnitude modification, or a combination of both and is applied by adjusting the phase of the fragment. The predistorted component is then separately processed by the signal processing subsystem. The processing may take the form of phase modulation and amplification. The phase modulated and amplified components are then recombined to arrive at an amplitude and phase modulated and amplified output signal. The predistortion modification is applied to the components to compensate for distortions introduced in the signal by the signal processing subsystem.

Predistortion circuit for a transmit system

The invention relates to the field of wireless communications, more particularly to a method of and device for switching between antennae in communication with a diversity receiver, each of the antennae receiving signals transmitted from a single source. A packet from a transmitter is received by respective antenna communicating with a diversity receiver. The signal strength of the preamble of the packet received in a first antenna is sampled. If the signal strength is of sufficient magnitude to affect reliable reception, the associated antenna is selected for the duration of the packet transmission. If the signal strength is below a predetermined threshold the signal strength of the preamble of the packet received in a second antenna is sampled and compared to the sample associated with the first antenna. If the magnitude of the second sample is greater, the signal associated with the second antenna is selected. To determine the signal strength, the arithmetic average of the signal power over a given period of the preamble is used.

Method of and device for antennae diversity switching

The present invention relates to wireless communications and is particularly applicable to devices and modules for correcting errors introduced to a wireless signal after its transmission. An equalizer is provided which compensates for undesirable effects on received radio signals introduced by either signal processing or by the transmission medium. In operation, the equalizer multiples the complex received signal with a complex corrective signal that compensates for these effects. A tap corrective signal corrects for time-varying channel effects (i.e. channel distortions), a timing tracking signal corrects for carrier frequency offset errors, and a phase tracking signal corrects for sampling frequency offset errors.

Frequency domain equalizer for wireless communications system

A mosaic image resembling a target image is composed of images from a data base. The target image is divided into regions of a specified size and shape, and the individual images from the data base are compared to each region to find the best matching tile. The comparison is performed by calculating a figure of visual difference between each tile and each region. The data base of tile images is created from raw source images using digital image processing, whereby multiple instances of each individual raw source image are produced. The tile images are organized by subject matter, and tile matching is performed such that all required subject matters are represented in the final mosaic. The digital image processing involves the adjustment of colour, brightness and contrast of tile images, as well as cropping. An image description index locates each image in the final mosaic.

Digital composition of a mosaic image

Systems and methods relating to the provision of gain, phase and delay adjustments to signals to be used by a predistortion subsystem. A portion of an input signal is delayed by delay elements prior to being received by the predistortion subsystem. The delayed input signal portion is also received by a feedback signal processing subsystem that adjusts the gain and phase of the feedback signal based on the delayed input signal portion. The adjusted feedback signal is used, along with the delayed portion of the input signal, to determine an appropriate predistortion modification to be applied to the input signal.

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Ottawa, Canada

Aryan Saed