Patent application number | Description | Published |
20080287072 | Detecting a signal in the presence of noise - In one embodiment, the present invention includes a method for receiving an incoming radio frequency (RF) signal in a receiver, estimating a signal-to-noise ratio (SNR) of a constant modulus (CM) signal in the incoming RF signal based on a calculated magnitude of the incoming RF signal, and indicating presence of a modulated signal in the incoming RF signal if the estimated SNR is greater than a threshold. | 11-20-2008 |
20090298453 | Combining multiple frequency modulation (FM) signals in a receiver - In one embodiment, the present invention provide a method for detecting signal quality metrics of a constant modulo (CM) signal received in two different signal paths, and combining the signal from the two signal paths based at least in part on the detected first and second signal quality metrics. Such method may be implemented in a radio receiver such as an automobile receiver. | 12-03-2009 |
20110075719 | Radio Receiver Having a Multipath Equalizer - A radio receiver has a multipath equalizer that includes a filter and a coefficient estimator. The filter provides a reconstructed signal by applying a transfer function including a reflection coefficient and a delay coefficient to a multipath radio signal. The coefficient estimator adapts the reflection coefficient and the delay coefficient in response to a deviation in magnitude of the reconstructed signal from a normalized value. In one form, the filter evaluates the transfer function by truncating it to eight terms. In another form, the filter includes a delay line having delay elements for storing samples of the multipath radio signal received both before and after a current sample. In yet another form, the multipath equalizer further includes a normalizer that receives the multipath radio signal and provides a normalized multipath radio signal having a normalized magnitude to an input of the filter. | 03-31-2011 |
20110075720 | Radio Receiver Having a Multipath Equalizer - A radio receiver has a multipath equalizer that includes a filter and a coefficient estimator. The filter provides a reconstructed signal by applying a transfer function including a reflection coefficient and a delay coefficient to a multipath radio signal. The coefficient estimator adapts the reflection coefficient and the delay coefficient in response to a deviation in magnitude of the reconstructed signal from a normalized value. In one form, the coefficient estimator adapts at least one of the reflection coefficient and the delay coefficient by estimating a partial derivative using a predetermined number of terms. In another form, the coefficient estimator acquires an initial value of the delay coefficient by determining a global minimum as a lowest one of a plurality of local minimums, each determined using a plurality of values of the delay coefficient, and selecting the initial value of the delay coefficient as its value at the global minimum. | 03-31-2011 |
20110158298 | TUNER CIRCUIT WITH AN INTER-CHIP TRANSMITTER AND METHOD OF PROVIDING AN INTER-CHIP LINK FRAME - A tuner circuit includes a digital signal processor to generate a digital data stream related to a radio frequency signal and a transceiver circuit coupled to the digital signal processor and configurable to generate an inter-chip communication frame having a start portion and a plurality of channels. The plurality of channels includes a first data channel to carry a portion of the digital data stream and a control channel to carry control data. The transceiver circuit is configurable to send the inter-chip communication frame to an additional tuner circuit through an inter-chip communication link. | 06-30-2011 |
20110158339 | ANTENNA DIVERSITY SYSTEM WITH MULTIPLE TUNER CIRCUITS HAVING MULTIPLE OPERATING MODES AND METHODS - In an embodiment, a tuner circuit includes an inter-chip receiver circuit configurable to couple to a first inter-chip communication link to receive a first data stream and includes an analog-to-digital converter configured to convert a radio frequency signal into a digital version of the radio frequency signal. The tuner circuit further includes a digital signal processor coupled to the inter-chip receiver circuit and the analog-to-digital converter. The digital signal processor is configurable to generate an output signal related to at least one of the first data stream and the digital version of the radio frequency signal based on a selected operating mode. | 06-30-2011 |
20110158357 | ANTENNA DIVERSITY SYSTEM WITH FRAME SYNCHRONIZATION - In an embodiment, a tuner circuit includes circuitry to produce a first DSP frame based on a first RF signal and includes an inter-chip receiver circuit coupled to an inter-chip link and configured to receive an inter-chip frame. The inter-chip receiver circuit is configured to detect a start of frame symbol of the inter-chip frame and to extract a DSP offset and data related to a second DSP frame from the inter-chip frame. The tuner circuit further includes a digital signal processor coupled to the circuitry and to the inter-chip receiver circuit. The digital signal processor is to synchronize the first DSP frame with the second DSP frame based on the start of frame symbol and the digital signal processor offset, the digital signal processor configured to perform a selected antenna diversity operation on the first and second DSP frames to produce an output signal. | 06-30-2011 |
20110275339 | Methods and systems for blending between stereo and mono in a FM receiver - Methods and systems for blending the audio output from a received FM signal between stereo and mono in which the L−R (left-minus-right) gain of the FM MPX may be adjusted as a function of RF signal to noise ratio (SNR) and the L+R (left-plus-right) noise level. During blending, the L−R gain based on the RF SNR and L+R noise may be reduced in a manner such that the total noise is kept substantially constant throughout the stereo-to-mono blend region. | 11-10-2011 |
20120082271 | DETECTING DIGITAL RADIO SIGNALS - In one embodiment, a receiver front end circuit can receive and process multiple radio frequency (RF) signals and output downconverted signals corresponding to these signals. In turn, multiple signal processors can be coupled to this front end. Specifically, a first signal processor can receive and process the downconverted signals to output a first signal obtained from content of a first RF signal, and a second signal processor can receive and process the downconverted signals to output a second signal obtained from content of a second RF signal. In addition, the apparatus may include a detection circuit coupled to the receiver front end circuit to detect presence of at least the second signal and enable the second signal processor responsive to the detected presence. | 04-05-2012 |
20120321012 | Providing Phase Diversity Combining Of Digital Radio Broadcast Signals - In one embodiment, a method for performing antenna diversity combining for digitally broadcast radio signals includes generating a first signal quality metric for a first signal obtained from an incoming digitally broadcast radio signal received in a first signal path, and similarly generating a second signal quality metric for a second signal obtained from the radio signal received in a second signal path. Then the first and second signals from these paths can be coherently combined based on the signal quality metrics to obtain a combined frequency domain symbol. In some embodiments, this combined frequency domain symbol may be remodulated to a time domain symbol. Also in some embodiments N tuners can be daisy chained to generate a final output that is either a frequency domain symbol of combined sub-carriers, soft bits to a forward error correction (FEC) decoder, or a remodulated time domain symbol. As a further possibility, each of the N tuners can use a different local oscillator (LO) frequency. | 12-20-2012 |
20130003637 | DYNAMIC TIME ALIGNMENT OF AUDIO SIGNALS IN SIMULCAST RADIO RECEIVERS - A method and apparatus for performing dynamic time alignment of program content extracted from analog and digital radio signals of a simulcast is disclosed. A delay estimation unit of a radio receiver is configured to dynamically determine an amount of received delay between analog-transmitted and digital portions of a radio program. An internal delay to compensate for the received delay may be applied to a data stream corresponding to the portion that is leading. The radio receiver may initially provide audio output from the analog-transmitted portion. In the case of leading analog-transmitted audio, the audio from the analog-transmitted portion may be incrementally delayed to align with the digitally transmitted audio. Once data streams corresponding to the analog-transmitted and digitally transmitted portions are sufficiently aligned in time, a blend operation may be performed. The blend operation may transition the output from being sourced by the analog-transmitted portion to the digitally-transmitted portion. | 01-03-2013 |
20130003801 | DELAYING ANALOG SOURCED AUDIO IN A RADIO SIMULCAST - A method and apparatus is disclosed in which delay is applied to analog-sourced audio in a radio simulcast when the analog signal initially leads the digital signal. A radio receiver is configured to receive a simulcast radio program broadcast with an analog signal and a digital signal. The program content can be extracted from either the analog or digital signals, with the audio source eventually being blended to the digital signal. Audio is initially provided based on the analog signal. If the analog signal is initially leading the digital signal, delay is applied a data stream corresponding to the analog signal relative to a data stream corresponding to the digital signal. Delay applied to the data stream corresponding to the analog signal is increased at a rate that avoids audio artifacts of the output audio. The blend is performed when the data streams are aligned in time. | 01-03-2013 |
20130003894 | DELAY ADJUSTMENT USING SAMPLE RATE CONVERTERS - A method and apparatus for adjusting the delay of a first data stream relative to a second data stream is disclosed. An apparatus receives first and second data streams having identical content. A timing difference between the first and second data streams is estimated. At least the leading one of the data streams is applied to a sample rate converter. The sample rate converter is configured to receive a data stream at an input sampling rate and to output the data stream at an output sampling rate. Based on the estimated timing difference, delay is applied to the leading one of the data streams by changing the sampling rate of the sampling rate converter. The output sampling rate of the sampling rate converter may be adjusted until both data streams are aligned in time. | 01-03-2013 |
20130003904 | DELAY ESTIMATION BASED ON REDUCED DATA SETS - A delay estimation unit is disclosed. The delay estimation unit may receive first and second streams of data having identical content. The amount of data in the data streams is reduced by filtering (e.g., lowpass filtering) the first and second data streams to produce first and second filtered streams, respectively. The amount of data is further reduced by decimating the first and second filtered streams, discarding all but one of every N samples to produce first and second decimated data, respectively. The first and second decimated streams are received by a correlator that performs a correlation operation. The output of the correlator is received by a peak search unit that analyzes the correlation results over time and searches for peaks that indicate alignment of the first and second data streams. | 01-03-2013 |
20130007082 | DIGITAL FRONT END FOR OVERSAMPLED LOW-IF OR ZERO-IF MULTIMODE RECEIVERS - A digital radio signal is processed by converting an analog signal to a digital signal, decimating the digital signal using a CIC filter and supplying the decimated digital signal directly to an asynchronous sample rate converter (ASRC). The decimated signal is resampled in the ASRC and the ASRC output is supplied directly to a droop compensation filter to compensate the output of the ASRC. By carefully choosing the response of the CIC filter and the resample rate of the ASRC, aliased artifacts in the pass band can be kept below a threshold magnitude without the need for a channelization filter. | 01-03-2013 |
20130084818 | Performing Power Control In A Receiver Based On Environmental Noise - In one embodiment, a method includes receiving and processing an incoming radio frequency (RF) signal in a receiver. Based on this signal, an environmental noise level can be determined, where this level corresponds to environmental noise present in an environment in which the receiver is located. Then, if the environmental noise level is substantially greater than receiver-generated noise, power consumption of at least one analog front end component of the receiver can be reduced. | 04-04-2013 |
20130322571 | SAMPLE RATE ESTIMATOR FOR DIGITAL RADIO RECEPTION SYSTEMS - A method and apparatus for adjusting a sample rate for an asynchronous sample rate converter is disclosed. In one embodiment, an apparatus includes an asynchronous sample rate converter (ASRC) that is configured to receive a digital data stream provided at a first sample rate. The ASRC is configured to convert the digital data stream to a second sample rate at which it is output. The apparatus also includes a sample rate estimator coupled to an interface through which samples from the digital data stream are conveyed subsequent to conversion to the second sample rate. The sample rate estimator is further coupled to the ASRC, and configured to adjust the second sample rate based on information obtained from the interface. | 12-05-2013 |
20130322572 | ASYNCHRONOUS SAMPLE RATE CONVERTER FOR DIGITAL RADIO TUNERS - A radio tuner and corresponding method of operating are disclosed. A radio tuner includes a radio frequency (RF) unit, an analog-to-digital converter (ADC), and an asynchronous sample rate converter (ASRC). The RF unit is configured to receive a radio signal and output a corresponding analog signal. The ADC is configured to generate a digital data stream, output at a first sample rate, based on the analog signal. The ASRC is coupled to receive the digital data stream and configured to output the digital data stream at a second sample rate for output do a demodulator. The demodulator may in turn be coupled to provide a feedback signal to the ASRC. The | 12-05-2013 |
20140094130 | Time-Domain Diversity Combining of Signals For Broadcast Receivers - Systems and methods are disclosed for time-domain diversity combining of radio frequency (RF) broadcast signals. Two channelized quadrature (I/Q) signals are generated by different tuner circuitry coupled to two different antennas, are converted to frequency-domain signals, and are used to generate frequency-domain diversity weighting signals. The frequency-domain diversity weighting signals are then converted to time-domain weights and applied to the channelized I/Q signals. The weighted and channelized I/Q signals are then combined in the time-domain to provide a time-domain diversity combined signal. The resulting combined signal can be further processed, as desired, such as by using a demodulator to generate demodulated output signals. Disclosed methods and systems can be applied to a variety of receiver systems configured to receive RF broadcast signals. | 04-03-2014 |
20140254729 | Detecting Digital Radio Signals - In one embodiment, a receiver front end circuit can receive and process multiple radio frequency (RF) signals and output downconverted signals corresponding to these signals. In turn, multiple signal processors can be coupled to this front end. Specifically, a first signal processor can receive and process the downconverted signals to output a first signal obtained from content of a first RF signal, and a second signal processor can receive and process the downconverted signals to output a second signal obtained from content of a second RF signal. In addition, the apparatus may include a detection circuit coupled to the receiver front end circuit to detect presence of at least the second signal and enable the second signal processor responsive to the detected presence. | 09-11-2014 |
20140355726 | Methods And Systems For Rapid Detection Of Digital Radio Signals - Systems and methods are disclosed for rapid detection of digital content within received radio frequency (RF) signals. The disclosed embodiments digitize received RF signals and apply a sliding window average to subsampled complex magnitudes for the digital samples to generate subsampled magnitude values. The subsampled magnitude values are then collected over a small number of symbols for the digital content, and the results are analyzed to determine whether or not digital content is present with the received signals. For example, multi-symbol histograms and magnitude ratios determined over multiple symbols can then be utilized to make the determination of whether digital content is present in the received signals. The resulting detection determination can be utilized further to control operations of systems utilizing the disclosed embodiments. The disclosed embodiments can be used, for example, to detect the presence of HD (High Definition) Radio digital content within broadcast channels. | 12-04-2014 |
20140355764 | Methods And Systems For Blending Between Analog And Digital Broadcast Signals - Systems and methods are disclosed that may be implemented to process a received RF spectrum that includes both analog modulated and digitally modulated RF signals to blend between a digital demodulated signal and an analog demodulated signal obtained from the received RF spectrum prior to performing one or more signal quality mitigation operations on the blended signal (e.g., such as stereo blend, hi-cut, etc.). In one embodiment, the digital demodulated signal and the analog demodulated signal may include at least some of the same information, e.g., such as information from simulcast digital and analog channels that are obtained from the same received RF spectrum. | 12-04-2014 |
20150063497 | Antenna Diversity Combining For Differentially Modulated Orthogonal Frequency Division Multiplexed (OFDM) Signals - In an embodiment, an apparatus includes a first tuner to receive a radio frequency (RF) signal from a first antenna and to process the RF signal to generate a first time-domain quadrature signal, a second tuner to receive the RF signal from a second antenna and to process the RF signal to generate a second time-domain quadrature signal, and a combiner circuit to receive the first and second time-domain quadrature signals. | 03-05-2015 |