Shure Acquisition Holdings, Inc.

Techwell, Inc.

Honghui Xu

Robert Mamola

Michael Joseph Goodson

Michael Rodriguez

Bryan W Zancho

Jiang Chang

Shidong Chen

Described are systems, methods, apparatuses, and computer program products for wireless in-ear-monitoring (IEM) of audio. A system includes transmitter(s) configured to map orthogonal sub-carriers of a digital signal to narrowband receivers to form receiver-allocated audio channels, modulate the digital signal, and transmit the signal as an ultra-high frequency (UHF) analog carrier wave comprising the orthogonal sub-carriers to the nearby receiver. A narrowband receiver is configured to demodulate and sample the sub-carriers allocated to the receiver. Sub-carriers can be positioned orthogonal to one another in adjacent sub-bands of the frequency domain and beacon symbols and pilot signals can be iteratively provided in the same portion of the frequency domain for each channel. The receiver can use non-data-aided and data-aided approaches for synchronization of the time domain and frequency domain waveforms of the received signal to the transmitted signal prior to sampling the allocated sub-carriers.

Scalable multiuser audio system and method

A method for synchronizing baseband clocks in an OFDMA wireless microphone system is disclosed. An example method includes receiving a plurality of pilot subcarriers from an audio transmitter. The method also includes determining a timing offset estimate based on the pilot subcarriers. The method further includes determining a tuning value by passing the timing offset estimate through a proportional-integral controller. The method still further includes determining a modified reference signal by modifying a reference oscillator based on the tuning value. And the method yet further includes controlling (i) an audio sample clock and (ii) an antenna data clock based on the modified reference signal.

OFDMA baseband clock synchronization

An automatic gain control ('AGC') system. The system includes a first multiplier, an envelope detector, a summation module, a filter module, a convergence module, and a feedback module. The convergence module includes a convergence control module and a second multiplier. The feedback module includes an accumulator, a scalar multiplier module, and a third multiplier. The system is configured to adjust or modify its convergence speed according to the state of convergence of the AGC system, and the convergence speed of the AGC system is substantially independent of a signal level of the received signal.

Digital automatic gain control

Systems and methods of carrier frequency acquisition or recovery in a receiver. The receiver is able to achieve carrier acquisition when a frequency offset is large (e.g., near a decision boundary). The receiver includes a demodulator, an equalizer, and a carrier recovery module. The carrier recovery module includes a decision device and phase detector, a phase error differentiator, a frequency direction confidence module, and a frequency and phase combiner module. The carrier recovery module calculates a phase error differential between a phase error at a first time and a phase error at a second time. Based on the phase error differential, the frequency direction confidence module generates a frequency offset confidence number. The frequency offset confidence number provides an indication of the direction of a frequency offset and a degree of certainty related to a detected direction (e.g., positive or negative) of the frequency offset. If the confidence number is greater than a threshold value, a joint frequency and phase lock loop ('FPLL') is used for carrier acquisition. If the confidence number is less than the threshold value, a phase lock loop ('PLL') is used for carrier acquisition.

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Buffalo Grove, IL, United States of America

Honghui Xu