Abstract: A method for processing audio signals in a radio transmitter, includes: receiving an analog audio sample stream and a digital audio sample stream; determining offsets in time between the analog audio stream and the digital audio stream using a normalized cross-correlation of audio envelopes of the analog audio sample stream and the digital audio sample stream; filtering the determined offsets in time to produce filtered offset values; determining an alignment slip adjustment value as a function of the filtered offset values; aligning the analog audio sample stream and the digital audio sample stream using the determined alignment slip adjustment value; and generating a hybrid radio signal for broadcast that includes time-aligned analog audio and digital audio.

Abstract: A method comprises receiving an approximate location of a rover platform based on satellite signals for a Global Navigation Satellite System (GNSS), and receiving for the GNSS a differential correction map (DCM) representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM. The differential corrections are based on a reference station constellation of GNSS reference stations having respective locations spanning the geographical area. The method further comprises deriving DCM-based differential corrections for the satellite signals at the approximate location based on the DCM, correcting the satellite signals using the DCM-based differential corrections, and determining a location of the rover platform using the corrected satellite signals.

Abstract: A method comprises generating for a Global Navigation Satellite System (GNSS) a differential correction map (DCM) representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM, the differential corrections being based on a reference station constellation of GNSS reference stations having respective locations spanning the geographical area, the GNSS reference stations including physical or virtual reference stations.

Abstract: A method for processing audio signals in a radio transmitter, includes: receiving an analog audio sample stream and a digital audio sample stream; determining offsets in time between the analog audio stream and the digital audio stream using a normalized cross-correlation of audio envelopes of the analog audio sample stream and the digital audio sample stream; filtering the determined offsets in time to produce filtered offset values; determining an alignment slip adjustment value as a function of the filtered offset values; aligning the analog audio sample stream and the digital audio sample stream using the determined alignment slip adjustment value; and generating a hybrid radio signal for broadcast that includes time-aligned analog audio and digital audio.

Abstract: A radio transmitter comprises transmitting circuitry and processing circuitry. The transmitting circuitry broadcasts a frequency modulation (FM) in-band on-channel (IBOC) radio signal, wherein the FM IBOC radio signal includes multiple subcarriers grouped into multiple frequency partitions. The processing circuitry is configured to receive input bits for transmitting; encode and puncture the input bits using forward error correction (FEC) encoding; distribute encoded input bits between a main encoded component and a backup encoded component, wherein encoded bits of the backup encoded component are delayed for a specified duration relative to encoded bits of the main encoded component; allocate the encoded input bits of the main and backup encoded components into frequency diverse sidebands of the FM IBOC radio signal; and modulate the encoded input bits for transmitting using the frequency diverse sidebands of the FM IBOC radio signal, wherein the modulation is a type of quadrature amplitude modulation (QAM).

Abstract: A method for processing audio signals in a radio transmitter, includes: receiving an analog audio sample stream and a digital audio sample stream; determining offsets in time between the analog audio stream and the digital audio stream using a normalized cross-correlation of audio envelopes of the analog audio sample stream and the digital audio sample stream; filtering the determined offsets in time to produce filtered offset values; determining an alignment slip adjustment value as a function of the filtered offset values; aligning the analog audio sample stream and the digital audio sample stream using the determined alignment slip adjustment value; and generating a hybrid radio signal for broadcast that includes time-aligned analog audio and digital audio.

Abstract: A method comprises generating for a Global Navigation Satellite System (GNSS) a differential correction map (DCM) representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM, the differential corrections being based on a reference station constellation of GNSS reference stations having respective locations spanning the geographical area, the GNSS reference stations including physical or virtual reference stations.

Abstract: A method comprises receiving an approximate location of a rover platform based on satellite signals for a Global Navigation Satellite System (GNSS), and receiving for the GNSS a differential correction map (DCM) representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM. The differential corrections are based on a reference station constellation of GNSS reference stations having respective locations spanning the geographical area. The method further comprises deriving DCM-based differential corrections for the satellite signals at the approximate location based on the DCM, correcting the satellite signals using the DCM-based differential corrections, and determining a location of the rover platform using the corrected satellite signals.

Abstract: A radio transmitter comprises transmitting circuitry and processing circuitry. The transmitting circuitry broadcasts a frequency modulation (FM) in-band on-channel (IBOC) radio signal, wherein the FM IBOC radio signal includes multiple subcarriers grouped into multiple frequency partitions. The processing circuitry is configured to receive input bits for transmitting; encode and puncture the input bits using forward error correction (FEC) encoding; distribute encoded input bits between a main encoded component and a backup encoded component, wherein encoded bits of the backup encoded component are delayed for a specified duration relative to encoded bits of the main encoded component; allocate the encoded input bits of the main and backup encoded components into frequency diverse sidebands of the FM IBOC radio signal; and modulate the encoded input bits for transmitting using the frequency diverse sidebands of the FM IBOC radio signal, wherein the modulation is a type of quadrature amplitude modulation (QAM).

Abstract: A radio receiver comprises physical layer circuitry and processor circuitry. The physical layer circuitry receives quadrature amplitude modulation (QAM) symbols via a plurality of subcarriers included in a broadcast radio signal. Each received QAM symbol is a complex symbol comprising multiple bits of encoded source information. The processing circuitry demodulates the received data symbols, generates a constellation sample for each received QAM symbol, generates a soft metric for each bit of encoded information of the received QAM symbols using the constellation sample, and multiplies the soft metric by a channel state information (CSI) weight to produce a Log-likelihood Ratio (LLR) approximation for each bit of encoded information of the received QAM symbols.

Abstract: A method for processing audio signals in a radio transmitter, includes: receiving an analog audio sample stream and a digital audio sample stream; determining offsets in time between the analog audio stream and the digital audio stream using a normalized cross-correlation of audio envelopes of the analog audio sample stream and the digital audio sample stream; filtering the determined offsets in time to produce filtered offset values; determining an alignment slip adjustment value as a function of the filtered offset values; aligning the analog audio sample stream and the digital audio sample stream using the determined alignment slip adjustment value; and generating a hybrid radio signal for broadcast that includes time-aligned analog audio and digital audio.

Abstract: A method for processing a digital signal includes: receiving a plurality of protocol data units, each having a header including a plurality of control word bits; and a plurality of audio frames, each including a cyclic redundancy check code; decoding the protocol data units using an iterative decoding technique, wherein the iterative decoding technique uses a soft output decoding algorithm for iterations after the first iteration; and using decoded cyclic redundancy check codes to flag the audio frames containing errors. A receiver that implements the method is also provided.

Abstract: A method for processing a digital audio broadcast signal in a radio receiver, includes: receiving a hybrid broadcast signal; demodulating the hybrid broadcast signal to produce an analog audio stream and a digital audio stream; and using a normalized cross-correlation of envelopes of the analog audio stream and the digital audio stream to measure a time offset between the analog audio stream and the digital audio stream. The time offset can be used to align the analog audio stream and the digital audio stream for subsequent blending of an output of the radio receiver from the analog audio stream to the digital audio stream or from the digital audio stream to the analog audio stream.

Abstract: A method for processing a digital audio broadcast signal in a radio receiver, includes: receiving a hybrid broadcast signal; demodulating the hybrid broadcast signal to produce an analog audio stream and a digital audio stream; and using a normalized cross-correlation of envelopes of the analog audio stream and the digital audio stream to measure a time offset between the analog audio stream and the digital audio stream. The time offset can be used to align the analog audio stream and the digital audio stream for subsequent blending of an output of the radio receiver from the analog audio stream to the digital audio stream or from the digital audio stream to the analog audio stream.

Abstract: A method for processing a digital audio broadcast signal in a radio receiver, includes: receiving a hybrid broadcast signal; demodulating the hybrid broadcast signal to produce an analog audio stream and a digital audio stream; and using a normalized cross-correlation of envelopes of the analog audio stream and the digital audio stream to measure a time offset between the analog audio stream and the digital audio stream. The time offset can be used to align the analog audio stream and the digital audio stream for subsequent blending of an output of the radio receiver from the analog audio stream to the digital audio stream or from the digital audio stream to the analog audio stream.

Abstract: A method for processing a digital audio broadcast signal in a radio receiver, includes: receiving a hybrid broadcast signal; demodulating the hybrid broadcast signal to produce an analog audio stream and a digital audio stream; and using a normalized cross-correlation of envelopes of the analog audio stream and the digital audio stream to measure a time offset between the analog audio stream and the digital audio stream. The time offset can be used to align the analog audio stream and the digital audio stream for subsequent blending of an output of the radio receiver from the analog audio stream to the digital audio stream or from the digital audio stream to the analog audio stream.

Abstract: A method for processing a digital audio broadcast signal in a radio receiver includes: receiving a digital audio broadcast signal; demodulating the digital audio broadcast signal to produce an analog audio stream and a digital audio stream; determining a digital signal quality value for the digital audio stream; blending an output of the radio receiver from the analog audio stream to the digital audio stream when the digital signal quality value exceeds an adaptive analog-to-digital threshold value; and blending the output of the radio receiver from the digital audio stream to the analog audio stream when the digital signal quality value falls below an adaptive digital-to-analog threshold value, wherein the adaptive digital-to-analog threshold value is lower than the adaptive analog-to-digital threshold value.

Abstract: A method for processing a digital audio broadcast signal in a radio receiver includes: receiving a digital audio broadcast signal; demodulating the digital audio broadcast signal to produce an analog audio stream and a digital audio stream; determining a digital signal quality value for the digital audio stream; blending an output of the radio receiver from the analog audio stream to the digital audio stream when the digital signal quality value exceeds an adaptive analog-to-digital threshold value; and blending the output of the radio receiver from the digital audio stream to the analog audio stream when the digital signal quality value falls below an adaptive digital-to-analog threshold value, wherein the adaptive digital-to-analog threshold value is lower than the adaptive analog-to-digital threshold value.

Abstract: A method is disclosed which comprises receiving a radio signal; sampling and filtering the radio signal to isolate the FM portion; demodulating the FM portion of the received signal; applying a sliding window to the first, second, and third samples; and, adjusting the value of the second sample if the product of the second sample times the sum of the first and third samples is less than a threshold value. In various embodiments, an apparatus may be provided which comprises an input for receiving a radio signal and processing circuitry for performing various methods described herein.

Abstract: A method for processing a digital audio broadcast signal in a radio receiver, includes: receiving a hybrid broadcast signal; demodulating the hybrid broadcast signal to produce an analog audio stream and a digital audio stream; and using a normalized cross-correlation of envelopes of the analog audio stream and the digital audio stream to measure a time offset between the analog audio stream and the digital audio stream. The time offset can be used to align the analog audio stream and the digital audio stream for subsequent blending of an output of the radio receiver from the analog audio stream to the digital audio stream or from the digital audio stream to the analog audio stream.