Digital phase-lock loop network
First Claim
1. A phase-lock loop network for providing data sample-clock timing in a digital signal processing system receiving digital information defined by frames of multiple adjacent carriers transmitted simultaneously, wherein the digital processing system includes a data buffer receiving a number of data samples at predefined intervals and means for providing a synchronization signal corresponding to commencement of the predefined intervals, the network comprising:
- means for providing a fixed frequency signal;
means for providing a variable frequency signal;
means for maintaining a count of the data samples within the data buffer; and
means responsive to the synchronization signal for providing a data input clock according to said fixed frequency signal to the data buffer to thereby clock the number of data samples therein, and further responsive to the count of data samples within the data buffer for controlling the frequency of said variable frequency signal and providing a data output clock according to said variable frequency signal to the data buffer to thereby clock the number of data samples from the data buffer while maintaining a nominal number of data samples therein.
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Accused Products
Abstract
A digital phase-lock loop network that provides input and output clock signals to a digital data receiving system generally, and particularly to a data buffer contained therein, is disclosed. The digital phase-lock loop network provides bit-clock synchronization using a fixed input clock and an output clock having a variable frequency that is adjusted to correspond to the average input rate of the data samples into the data buffer. The digital phase-lock loop network allows the data buffer to be operated as a temporary storage device maintaining a nominal number of data samples therein at all times by avoiding any overflow and underflow data handling conditions that may otherwise cause loss of data. The digital phase-lock loop network of the present invention is particularly suited for the Eureka-147 system which has become a worldwide standard for digital audio broadcasting (DAB) technology.
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Citations
18 Claims
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1. A phase-lock loop network for providing data sample-clock timing in a digital signal processing system receiving digital information defined by frames of multiple adjacent carriers transmitted simultaneously, wherein the digital processing system includes a data buffer receiving a number of data samples at predefined intervals and means for providing a synchronization signal corresponding to commencement of the predefined intervals, the network comprising:
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means for providing a fixed frequency signal; means for providing a variable frequency signal; means for maintaining a count of the data samples within the data buffer; and means responsive to the synchronization signal for providing a data input clock according to said fixed frequency signal to the data buffer to thereby clock the number of data samples therein, and further responsive to the count of data samples within the data buffer for controlling the frequency of said variable frequency signal and providing a data output clock according to said variable frequency signal to the data buffer to thereby clock the number of data samples from the data buffer while maintaining a nominal number of data samples therein. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. In combination:
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a digital signal processing system including a data buffer having a first input receiving a data input clock signal, a second input receiving a number of data samples in accordance with clock pulses of the data input clock signal, a third input receiving a data output clock signal, and an output providing the number of data samples in accordance with pulses of the data output clock signal; and a phase-lock loop network for providing the data input and output clock signals, the network comprising; a clock generator having a first input receiving a frequency control signal, a first output providing a first clock signal, and a second output providing a second clock signal, said second clock signal having a frequency defined by said frequency control signal; a clock controller having a first input receiving said first clock signal and a first output providing the data input clock signal according thereto, a second input receiving said second clock signal and a second output providing the data output clock signal according thereto, a third input receiving a count signal corresponding to a count of the number of data samples within the data buffer, and a third output providing said frequency control signal in accordance with said count signal to thereby cause the frequency of said second clock signal to vary in accordance with the number of data samples within the data buffer, said second clock signal thereby maintaining a nominal number of data samples within the data buffer; and a data buffer counter having a first input receiving the data input clock signal and an output providing said count signal, said data buffer counter incrementing the count of data samples with each clock pulse of the data input clock signal, comparing the count of data samples with said nominal number of data samples, and providing said count signal in accordance with deviation of the count of data samples from said nominal number of data samples. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification