Abstract: A method for processing a radio signal includes: receiving an FM in-band on-channel radio signal including a plurality of digitally modulated subcarriers in upper and lower sidebands; sampling the FM in-band on-channel radio signal to produce an input signal including complex digital samples of a combination of a desired one the upper and lower sidebands and an FM interferer; removing FM interferer components from the first signal by notch filtering to produce a notch-filtered signal; weighting the notch-filtered signal to produce a weighted notch-filtered signal; using a parametric filter to filter the input signal to produce a parametric-filtered input signal; and combining the weighted notch-filtered signal and the parametric-filtered input signal to produce an output signal. A radio receiver that implements the method is also included.

Abstract: A method of transmitting digital information includes: receiving a plurality of information bits representing audio information and/or data; encoding the information bits using complementary low density parity check coding to produce a composite codeword and a plurality of independently decodable semi-codewords; modulating at least one carrier signal with the forward error corrected bits; and transmitting the carrier signal(s). Transmitters that implement the method, and receivers that receive signals produced by the method, are also provided.

Abstract: A method and apparatus are provided for processing a received digital radio broadcast signal to efficiently remove signal interference artifacts from digital and/or analog signals by using signal quality information extracted from audio samples in one or more buffered audio frames to detect audio frames containing clipped noise artifacts and weaker noise artifacts and to selectively apply anti-interference processing to remove the signal interference artifacts.

Abstract: A data link manager includes a User Datagram Protocol (UDP) receiver for receiving HD Radio broadcast equipment communication protocol (HDP) data or non-HD Radio broadcast equipment communication protocol (non-HDP) data using a User Datagram Protocol/Internet Protocol (UDP/IP) protocol; a Transmission Control Protocol (TCP) receiver; and a router for receiving data from the UDP receiver and the TCP receiver, for searching for a destination route in a routing table, and for forwarding the data received from the from the UDP receiver and the TCP receiver to an identified destination route.

Abstract: A method for receiving and processing a digital radio broadcasting signal includes: receiving a digital radio broadcasting signal including encoded content in a first format; processing the encoded content to convert the encoded content into a second format; storing the encoded content in a second format; and decoding the stored encoded content to recover decoded content. A receiver that implements the method is also provided.

Abstract: A method is provided for estimating channel state information in an in-band on-channel radio signal including a plurality of digitally modulated reference subcarriers. The method includes: receiving symbols transmitted on the reference subcarriers; combining the reference subcarrier symbols with a known reference sequence conjugate to produce a plurality of samples; median filtering the samples to produce filtered samples; smoothing the samples for each of the reference subcarriers over the plurality of reference subcarriers to produce a complex channel gain estimate for each of the subcarriers; and using a bias correction function to compensate for estimation bias error in the complex channel gain estimate due to the median filtering. Receivers that implement the method are also provided.

Abstract: A method and apparatus are provided for blending analog and digital portions of a composite digital audio broadcast signal by using look ahead metrics computed from previously received audio frames to guide the blending process and prevent unnecessary blending back and forth between analog and digital if the look ahead metrics indicate that future digital signal quality is degraded or impaired.

Abstract: A method for processing a radio signal includes: receiving a signal on two antennas; demodulating the signal using first and second independent signal paths that are synchronized by symbol number; maximum ratio combining branch metrics from the two receiver paths; and using the combined branch metrics to produce an output, wherein the receiver paths include an arbitration scheme. A receiver that implements the method is also provided.

Abstract: Methods and systems for preparing data for broadcast via digital radio broadcast transmission is disclosed comprising the steps of receiving a plurality of content files corresponding to programming information for program content to be broadcast; receiving an index file having a pointer for each of the plurality of content files, wherein the index file is associated with a first logical address; storing the index file and the plurality of content files; scheduling a broadcast rotation of the index file and the plurality of content files (wherein the index file is scheduled for repeated transmission intermittently relative to selected ones of the content files); and transmitting the index file and the plurality of content files to an importer in accordance with the broadcast rotation.

Abstract: A method is provided for equalizing OFDM symbol vectors received on AM in-band on-channel radio signal including a main carrier and first and second BPSK modulated subcarriers. The method comprises: computing a BPSK magnitude signal; filtering the BPSK magnitude signal; filtering complex samples received on the main carrier; using the filtered BPSK magnitude signal and the filtered complex samples received on the main carrier to compute a plurality of flat fade equalization coefficients; and multiplying the OFDM symbol vectors by the flat fade equalization coefficients. A receiver that includes an equalizer, which operates in accordance with the method is also provided.

Abstract: A method and apparatus are provided for recovering audio packet location fields and/or frame boundary information from a received digital radio broadcast signal frame in which there are detected errors in the signal frame header by using selected header elements and/or protocol data unit (PDU) structured data block parameters relating to minimum, maximum, and average packet length or PDU length in a scalable recovery process that may be throttled dynamically or configured statically based on available computation resources within a specific implementation and/or at a specific time.

Abstract: A method and apparatus are provided for processing a received digital radio broadcast signal to efficiently remove signal interference artifacts from digital and/or analog signals by using signal quality information extracted from audio samples in one or more buffered audio frames to detect audio frames containing clipped noise artifacts and weaker noise artifacts and to selectively apply anti-interference processing to remove the signal interference artifacts.

Abstract: A radio receiver includes a first signal path including a first tuner configured to receive a first signal from a first antenna, and a first demodulator configured to demodulate symbols from an output of the first tuner to produce first branch metrics derived from the demodulated symbols; a second signal path including a second tuner configured to receive a second signal from a second antenna, and a second demodulator configured to demodulate symbols from an output of the second tuner to produce second branch metrics derived from the demodulated symbols; a combiner for maximum ratio combining the first branch metrics and the second branch metrics; and processing circuitry to process the combined first and second branch metrics to produce an output signal.

Abstract: A method for detecting the digital quality of a radio signal includes: receiving a radio signal including a digital portion modulated by a series of symbols each including a plurality of samples; computing correlation points between endpoint samples in cyclic prefix regions of adjacent symbols; and using the correlation points to produce a digital signal quality metric. Receivers that implement the method are also provided.

Abstract: Systems, methods, and processor readable media are disclosed for encoding and transmitting first media content and second media content using a digital radio broadcast system, such that the second media content can be rendered in synchronization with the first media content by a digital radio broadcast receiver. The disclosed systems, methods, and processor-readable media determine when a receiver will render audio and data content that is transmitted at a given time by the digital radio broadcast transmitter, and adjust the media content accordingly to provide synchronized rendering. In exemplary embodiments, these adjustments can be provided by: 1) inserting timing instructions specifying playback time in the secondary content based on calculated delays; or 2) controlling the timing of sending the primary or secondary content to the transmitter so that it will be rendered in synchronization by the receiver.

Abstract: A method includes: (a) modulating a set of subcarriers with a set of data to produce a modulated OFDM symbol vector; (b) modulating a FM carrier signal with the set of data to produce a modulated FM symbol; (c) combining the modulated OFDM symbol and the modulated FM symbol to produce a modulated hybrid symbol; (d) limiting the magnitude of the modulated hybrid symbol to produce a first limited modulated hybrid symbol; (e) demodulating the first limited modulated hybrid symbol to recover distorted QPSK constellations; (f) constraining the distorted QPSK constellations to values greater than or equal to a minimum threshold value to produce constrained QPSK constellations; (g) demodulating the modulated hybrid symbol to produce a demodulated hybrid symbol vector; (h) subtracting the demodulated FM symbol vector from the Hybrid symbol vector to produce modified OFDM symbol vector; (i) applying a mask to inactive subcarriers in the plurality of subcarriers of the OFDM symbol vector; (j) modulating an OFDM symbol

Abstract: A method for specifying content of interest using a digital radio broadcast receiver is described. A digital radio broadcast signal includes first audio content and first program data, wherein the first program data includes information identifying a first item, and includes second audio content and second program data, wherein the second program data includes information identifying a second item. A user command entered at a user interface during reception of audio content is registered, indicating a user's interest in either the first or second audio content. It is determined whether there is an ambiguity in the content of interest. If there is an ambiguity, a first data structure is stored for the first audio content, and a second data structure is stored for the second audio content. The first data structure includes the information identifying the first item, and the second data structure includes the information identifying the second item.

Abstract: A method for receiving and processing a digital radio broadcasting signal includes: receiving a digital radio broadcasting signal including encoded content in a first format; processing the encoded content to convert the encoded content into a second format; storing the encoded content in a second format; and decoding the stored encoded content to recover decoded content. A receiver that implements the method is also provided.

Abstract: A digital radio broadcast system includes a processing system that receives first audio content, first program data identifying a first item for the first audio content, second audio content, and second program data identifying a second item for the second audio content such that a start of the first program data is received at the processing system within 0.5 seconds of a start of the first audio content. A digital radio broadcast signal including the audio content and the program data is processed for digital radio broadcast transmission via a transmitter. The processing system stops delivery of the first program data to the transmitter upon receipt of the second program data, the first program data thereby being truncated, and begins delivery of the second program data to the transmitter. A digital radio broadcast receiver can tag content of interest based on a user command registered at the receiver.

Abstract: Systems, methods, and processor readable media are disclosed for scheduling and delivering content for digital radio broadcast transmission. To overcome the inefficiencies of conventional scheduling and delivery techniques, the present disclosure describes a novel multiport synchronous-asynchronous client for receiving content from multiple sources and then scheduling and delivering that content to an importer.