Abstract:
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.
Abstract:
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 synchronizes 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 performs a selected antenna diversity operation on the first and second DSP frames to produce an output signal.
Abstract:
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.
Abstract:
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.
Abstract:
A transceiver includes a processor and an analog-to-digital converter. The processor is adapted to in a transmit mode of the transceiver, generate a modulated signal in response to a first digital signal. In a receive mode of the transceiver, the processor is adapted to generate a demodulated signal in response to a second digital signal. The analog-to-digital converter provides the first digital signal in the transmit mode and provides the second digital signal in the receive mode.
Abstract:
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.
Abstract:
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.
Abstract:
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.
Abstract:
A frequency modulation (FM) radio receiver includes a processing unit that may generate a magnitude value corresponding to a signal strength of each of a plurality of digital samples of a received FM signal. The receiver also includes a noise estimation unit that may filter the magnitude values using a high pass filter and may generate a noise value representative of a noise portion of the received FM signal based upon the filtered magnitude values.
Abstract:
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.