Abstract: 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.

Abstract: 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.

Abstract: 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.

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.

Abstract: 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.

Abstract: 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.