Abstract: Systems and method are provided herein for balancing of outputs from playback devices playing audio content in synchrony. In one embodiment, the balancing of outputs may involve receiving a first audio signal to be played by a first playback device according to a first crossover frequency, determining a limiting result by applying a limiting function associated with a second playback device to a second audio signal to be played by the second playback device according to a second crossover frequency, and based on the first limiting result, configuring the first playback device to play the first audio signal according to a third crossover frequency. In some cases, the first and second playback devices may be configured to play the first and second audio signals, respectively, in synchrony.

Abstract: Embodiments are provided for audio synchronization of one or more playback devices using offset information. A playback device may join a synchrony group upon a command, where the synchrony group may have a group coordinator that provides timing information for the group. In one case, the playback device may retrieve offset information from memory storage, where the information represents the offset between a clock of the playback device and the clock of the group coordinator. In another case, the playback device may determine that the offset information is not available in storage and as a result, the offset information may be computed. In one instance, the offset information may be computed using other offsets obtained from storage, such as offsets between other devices in the synchrony group. In another instance, the offset information may be computed using SNTP polling.

Abstract: Systems, methods, apparatus, and articles of manufacture are disclosed. An example playback device includes a signal detector adjacent to a first side of the playback device; a signal emitter adjacent to a second side of the playback device; a processor; and memory having stored thereon instructions executable by the processor to cause the playback device to perform functions. The example functions include detecting, by the signal detector, an analog signal; amplifying the analog signal in analog form; applying an offset to analog signal in analog form; filtering the offset signal in analog form; and emitting, by the signal emitter, the filtered signal.

Abstract: Methods and systems are provided for adjusting a crossover frequency between a plurality of audio speakers rendering audio content. In one example, a first subset of a plurality of audio speakers may be rendering a first sub-range of a range of audio frequencies of an audio content, and a second subset of speakers of the plurality of audio speakers may be rendering a second sub-range of the range of audio frequencies. In this example, the first sub-range and the second sub-range may be substantially separated at the crossover frequency. In one case, a characteristic of the audio content may be determined, and the crossover frequency may be adjusted based on the determined characteristic to help improve the audio content rendering quality by the respective subsets of audio speakers in the plurality of audio speakers.

Abstract: An apparatus for driving speakers includes user-configurable amplifier cells for driving selected speakers, a synchronous rectifier circuit, and a control system. Each cell connects between power rails. The rectifier circuit provides current on the rails for consumption by the cells. The current depends on the configuration. The control system implements a model of the rectifier circuit and cells and uses it to control an audio input signal in response to information concerning electrical outputs of the amplifier cells. This indirectly limits current drawn from the synchronous rectifier circuit.

Abstract: Systems, methods, apparatus, and articles of manufacture to provide an infrared signal are disclosed. An example apparatus includes an infrared provider to receive a first signal from a first device. The first signal is analog and representative of a command. The example infrared provider is to linearly manipulate the first signal in analog form, wherein the manipulated signal remains analog. The example infrared provider is to relay the manipulated signal to a second device. The relayed manipulated signal is representative of the command and is indistinguishable from the first signal.

Abstract: Methods and systems are provided for adjusting a crossover frequency between a plurality of audio speakers rendering audio content. In one example, a first subset of a plurality of audio speakers may be rendering a first sub-range of a range of audio frequencies of an audio content, and a second subset of speakers of the plurality of audio speakers may be rendering a second sub-range of the range of audio frequencies. In this example, the first sub-range and the second sub-range may be substantially separated at the crossover frequency. In one case, a playback volume at which the audio content is being rendered may be adjusted. In one instance, the crossover frequency may be adjusted in response to the volume adjustment to improve the audio content rendering quality by the respective subsets of audio speakers in the plurality of audio speakers.

Abstract: Methods and systems are provided for adjusting a crossover frequency between a plurality of audio speakers rendering audio content. In one example, a first subset of a plurality of audio speakers may be rendering a first sub-range of a range of audio frequencies of an audio content, and a second subset of speakers of the plurality of audio speakers may be rendering a second sub-range of the range of audio frequencies. In this example, the first sub-range and the second sub-range may be substantially separated at the crossover frequency. In one case, a playback volume at which the audio content is being rendered may be adjusted. In one instance, the crossover frequency may be adjusted in response to the volume adjustment to improve the audio content rendering quality by the respective subsets of audio speakers in the plurality of audio speakers.

Abstract: Systems, methods, apparatus, and articles of manufacture to provide an infrared signal are disclosed. An example apparatus includes an infrared provider to receive a first signal from a first device. The first signal is analog and representative of a command. The example infrared provider is to linearly manipulate the first signal in analog form, wherein the manipulated signal remains analog. The example infrared provider is to relay the manipulated signal to a second device. The relayed manipulated signal is representative of the command and is indistinguishable from the first signal.

Abstract: An apparatus for driving speakers includes user-configurable amplifier cells for driving selected speakers, a synchronous rectifier circuit, and a control system. Each cell connects between power rails. The rectifier circuit provides current on the rails for consumption by the cells. The current depends on the configuration. The control system implements a model of the rectifier circuit and cells and uses it to control an audio input signal in response to information concerning electrical outputs of the amplifier cells. This indirectly limits current drawn from the synchronous rectifier circuit.

Abstract: A topology for converting analog signals to digital signals includes a plurality of analog-to-digital converters each having an analog input and a digital output. The analog inputs are coupled to one another, and the digital outputs are coupled to different inputs of a crossover filter. The crossover filter blends together the outputs of the converters to generate a single digital output, which has a uniform response, or a desired non-uniform response, and is substantially free of unwanted distortion.

Abstract: A circuit topology and method for converting a digital input signal to an analog output signal employs a modified sigma-delta loop and a DAC, and operates with improved accuracy over a wide frequency range. A loop filter such as a digital accumulator receives an input signal proportional to the difference between a digital input signal and a feedback signal. A quantizer quantizes the output of the loop filter, and the DAC converts the quantized signal into an analog output signal. The quantized signal is also provided to a DAC model. In response to the quantized signal and behavioral information about the DAC, the DAC model varies the feedback signal to match expected output signals from the DAC, including errors introduced by the DAC. By the operation of the sigma-delta loop, the errors of the DAC are substantially reduced.

Abstract: A clock generator for automatic test equipment employs an improved technique for generating clock signals from a reference clock. To generate a desired clock signal, a clock generator produces a time-quantized signal having a period equal to an integer number of reference clock periods and equal to the desired clock period, plus or minus a quantization error. For each cycle of the desired clock signal, a noise-shaping requantizer processes the quantization error to generate noise-shaping signals. The noise-shaping signals then establish delay values of a variable pipeline delay. The variable pipeline delay adjusts each period of the time-quantized signal by an integer number of reference clock cycles, based upon the noise-shaped signals. The effect of noise shaping the quantization error and selectively delaying the time-quantized signal is to shift jitter in the time-quantized signal from relatively low frequencies to relatively high frequencies.

Abstract: A timing circuit for ATE generates an output clock from an input clock and controls output pulse width. The timing circuit includes a differential driver having an input that receives the input clock, and having inverting and non-inverting outputs. The inverting output is coupled to a first phase-locked loop, and the non-inverting output is coupled to a second phase-locked loop. The first and second phase-locked loops respectively generate first and second clocks in response to respective rising and falling edges of the input clock. A combiner circuit converts the first and second clocks into narrow pulse trains, and the pulse trains respectively operate SET and RESET inputs of a SET/RESET flip-flop. The SET/RESET flip-flop generates an output clock having rising edges responsive to rising edges of the input clock, and falling edges responsive to falling edges of the input clock.

Abstract: An apparatus and method are disclosed for testing connections between printed circuit boards and components mounted thereon. A conductive loop is formed by forward biasing a parasitic diode that is inherently present between an integrated circuit (IC) lead and the ground plane of the IC. A magnetic field is created by an antenna mounted above the component to be tested. When the antenna is energized by an RF source, a voltage is induced in the conductive loop if the loop is continuous, i.e., if all of the connections are properly made. The voltage in the loop is measured and compared to a selected threshold to produce a pass/fail indication. This tester may be implemented as an improvement to a standard type of "bed-of-nails" printed circuit board tester. The antenna may be implemented as an array of spiral loop antennas, with adjacent antennas producing magnetic fields that are 90 degrees out of phase with each other.

Abstract: A manufacturing defect analyzer for printed circuit boards which can detect open circuit faults between leads of components and the printed circuit board. The manufacturing defect analyzer can operate in an inductive coupling mode or a capacitive coupling mode. The same sensors are used in each mode, allowing different leads on the same part to be tested using either technique. A method is also disclosed whereby the device is used to rapidly and accurately detect manufacturing defects.