Method for alignment of analog and digital audio in a hybrid radio waveform
AssigneeiBiquity Digital Corporation
InventorsRussell Iannuzzelli, Brian William Kroeger, Harvey Chalmers
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Abstract
This invention provides a method of detecting time alignment of an analog audio signal and a digital audio signal in a hybrid radio system. The method comprises the steps of filtering the analog audio signal to produce a filtered analog audio signal, filtering the digital audio signal to produce a filtered digital audio signal, and using the filtered analog audio signal and the filtered digital audio signal to calculate a plurality of correlation coefficients, wherein the correlation coefficients are representative of time alignment between the analog audio signal and the digital audio signal. An apparatus for performing the method is also provided.
Claims15
A method comprising the steps of:
- using a transmitter to transmit an analog audio signal and a digital audio signal in a hybrid waveform;
- receiving the hybrid waveform including a carrier signal modulated by the analog audio signal and a plurality of subcarriers modulated by the digital audio signal;
- filtering the analog audio signal to produce a filtered analog audio signal having a reduced bandwidth;
- filtering the digital audio signal to produce a filtered digital audio signal having a reduced bandwidth;
- using the filtered analog audio signal and the filtered digital audio signal to calculate a plurality of correlation coefficients, wherein the correlation coefficients are representative of time alignment between the analog audio signal and the digital audio signal;
- and
- adjusting the timing of the analog audio signal or the digital audio signal at the transmitter in response to the correlation coefficients.
A method of detecting level alignment of an analog audio signal and a digital audio signal in a hybrid radio system comprising the steps of:
- receiving a hybrid waveform transmitted by a transmitter and including a carrier signal modulated by an analog audio signal and a plurality of subcarriers modulated by a digital audio signal;
- filtering the analog audio signal to produce a filtered analog audio signal having a reduced bandwidth;
- filtering the digital audio signal to produce a filtered digital audio signal having a reduced bandwidth;
- computing the signal power of the analog audio signal and the signal power of the digital audio signal for an audio segment;
- using a ratio of the signal power of the analog audio signal and the signal power of the digital audio signal to produce a signal representative of a level alignment of the analog audio signal and the digital audio signal;
- and
- adjusting the level of the analog audio signal or the digital audio signal at the transmitter in response the signal representative of a level alignment.
An apparatus comprising:
- a transmitter for transmitting a hybrid waveform including a carrier signal modulated by an analog audio signal and a plurality of subcarriers modulated by a digital audio signal;
- an input for receiving the hybrid waveform;
- a first filter for filtering the analog audio signal to produce a filtered analog audio signal having a reduced bandwidth;
- a second filter for filtering the digital audio signal to produce a filtered digital audio signal having a reduced bandwidth;
- a processor for using the filtered analog audio signal and the filtered digital audio signal to calculate a plurality of correlation coefficients, wherein the correlation coefficients are representative of time alignment between the analog audio signal and the digital audio signal;
- and
- an audio processor for adjusting the timing of the analog audio signal or the digital audio signal at the transmitter in response to the correlation coefficients.
An apparatus comprising:
- a transmitter for transmitting a hybrid waveform including a carrier signal modulated by an analog audio signal and a plurality of subcarriers modulated by a digital audio signal;
- an input for receiving the hybrid waveform including a carrier signal modulated by an analog audio signal and a plurality of subcarriers modulated by a digital audio signal;
- a first filter for filtering the analog audio signal to produce a filtered analog audio signal having a reduced bandwidth;
- a second filter for filtering the digital audio signal to produce a filtered digital audio signal having a reduced bandwidth;
- a processor for computing the signal power of the filtered analog audio signal and the signal power of the filtered digital audio signal for an audio segment, and for using a ratio of the signal power of the filtered analog audio signal and the signal power of the filtered digital audio signal to produce a signal representative of a level alignment of the analog audio signal and the digital audio signal;
- and
- an audio processor for adjusting the level of the analog audio signal or the digital audio signal at the transmitter in response to the signal representative of a level alignment.
Dependencies are inferred from the claim text.